DE112022004364T5 - TRANSMISSION OF SIGNALS FOR DISTANCE MEASUREMENT, TIME CONTROL AND DATA TRANSMISSION - Google Patents

Abstract

An apparatus is disclosed. In one or more examples, the apparatus may include an antenna to receive a signal encoding timing information for one or more of positioning, navigation, and timing. The signal may include a pulse group comprising a number of ranging pulses and a number of data pulses subsequent to the number of ranging pulses. Corresponding ones of the number of data pulses may have a phase of either a positive going phase or a negative going phase. Data may be encoded using either the positive going phases or the negative going phases of the data signals. The apparatus may include a processor to decode the data at least partially in response to the phases of the respective ones of the number of data pulses.

Description

PRIORITY CLAIM

This application claims the benefit under 35 USC §119(e) of U.S. provisional patent application serial number 63/262,729 , filed October 19, 2021, for “TRANSMISSION OF SIGNALS FOR RANGING, TIMING, AND DATA TRANSFER,” U.S. provisional patent application serial number 63/262,728 , filed October 19, 2021, for “TRANSMISSION OF SIGNALS FOR DISTANCE MEASUREMENT, TIMING AND DATA TRANSMISSION” and U.S. patent application serial number 17/447,392 , filed September 10, 2021, for “TRANSMISSION OF SIGNALS FOR DISTANCE MEASUREMENT, TIMING, AND DATA TRANSMISSION,” each of the disclosures of which is hereby incorporated in its entirety herein by this reference.

STATE OF THE ART

Transmitters of radio waves (e.g. ground-based radio waves) are sometimes used to send signals for positioning, navigation, or timing. An example system for transmitting such signals is LORAN (Long Range Navigation) and variations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1A veranschaulicht beispielhafte Impulsgruppen einer beispielhaften Epoche gemäß einem oder mehreren Beispielen.
• 1B veranschaulicht beispielhafte Impulse innerhalb einer beispielhaften Impulsgruppe gemäß einem oder mehreren Beispielen.
• 1C veranschaulicht einen beispielhaften Impuls gemäß einem oder mehreren Beispielen.
• 1D veranschaulicht einen beispielhaften Impuls gemäß einem oder mehreren Beispielen.
• 2 veranschaulicht ein Ordnungsschema für codierte Nachrichten gemäß einem oder mehreren Beispielen.
• 3 veranschaulicht beispielhafte Zeitsteuerungen von Impulsgruppen innerhalb von Epochen, die ein Dithering auf Kettenebene gemäß einem oder mehreren Beispielen aufweisen.
• 4 veranschaulicht ein Beispiel für Dithering auf Kettenebene im Laufe der Zeit gemäß einem oder mehreren Beispielen.
• 5 veranschaulicht Zeitsteuerungen von Impulsgruppen innerhalb einer Epoche, die ein Dithering auf Ketten- und Senderebene gemäß einem oder mehreren Beispielen aufweisen.
• 6 veranschaulicht ein Dithering auf Senderebene im Laufe der Zeit gemäß einem oder mehreren Beispielen.
• 7 veranschaulicht ein maskiertes Dithering im Laufe der Zeit gemäß einem oder mehreren Beispielen.
• 8A ist ein Graph, der einen positiven Phasencodeimpuls für einen beispielhaften Impuls gemäß einem oder mehreren Beispielen darstellt.
• 8B ist ein Graph, der die beispielhafte Impulsgruppe darstellt, die positive Phasencodeimpulse (z. B. von 8A) und negative Phasencodeimpulse (z. B. von 8C) einschließt.
• 8C ist ein Graph, der einen negativen Phasencodeimpuls für eine beispielhafte Impulsgruppe gemäß einem oder mehreren Beispielen darstellt.
• 9 veranschaulicht ein System, um eine oder mehrere offenbarte Techniken durchzuführen, wenn Funkwellen (z. B. Hochfrequenzbodenwellen) für Impulse gemäß einem oder mehreren Beispielen erzeugt werden.
• 10 ist ein Funktionsblockdiagramm, das logische Blöcke eines Systems veranschaulicht, um eine oder mehrere offenbarte Techniken durchzuführen, wenn Hochfrequenzbodenwellen für Impulse erzeugt werden, gemäß einem oder mehreren Beispielen.
• 11 ist ein Flussdiagramm, das ein Verfahren gemäß einem oder mehreren Beispielen veranschaulicht.
• 12A und 12B schließen gemeinsam ein Flussdiagramm eines Verfahrens gemäß einem oder mehreren Beispielen ein.
• 13 ist ein Flussdiagramm eines Verfahrens gemäß einem oder mehreren Beispielen.
• 14 ist ein Flussdiagramm eines Verfahren gemäß einem oder mehreren Beispielen.
• 15 ist ein Flussdiagramm eines Verfahrens gemäß einem oder mehreren Beispielen.
• 16 ist ein Funktionsblockdiagramm, das einen Empfänger gemäß einem oder mehreren Beispielen veranschaulicht.
• 17 ist ein Funktionsblockdiagramm, das ein System, das einen Sender und einen Empfänger einschließt, gemäß einem oder mehreren Beispielen veranschaulicht.
• 18 ist ein Funktionsblockdiagramm, das einen oder mehrere Vorgänge veranschaulicht, die an einem Empfänger gemäß einem oder mehreren Beispielen auftreten können.
• 19 ist ein Funktionsblockdiagramm, das eine oder mehrere Vorgänge veranschaulicht, die an einem Empfänger gemäß einem oder mehreren Beispielen auftreten können.
• 20 ist ein Flussdiagramm, das ein Verfahren zum Empfangen von Funkwellen und zum Decodieren von durch die Funkwellen codierten Daten gemäß einem oder mehreren Beispielen veranschaulicht.
• 21 ist ein Flussdiagramm, das ein Verfahren zum Empfangen von Funkwellen und zum Decodieren von durch die Funkwellen codierten Daten gemäß einem oder mehreren Beispielen veranschaulicht.

The purpose and advantages of the examples of the disclosure will become apparent to those skilled in the art from the detailed description taken in conjunction with the following accompanying drawings.

• 1A illustrates exemplary pulse groups of an exemplary epoch according to one or more examples.
• 1B illustrates example pulses within an example pulse group according to one or more examples.
• 1C illustrates an exemplary pulse according to one or more examples.
• 1D illustrates an exemplary pulse according to one or more examples.
• 2 illustrates an ordering scheme for coded messages according to one or more examples.
• 3 illustrates example timings of pulse groups within epochs having chain-level dithering according to one or more examples.
• 4 illustrates an example of chain-level dithering over time according to one or more examples.
• 5 illustrates timings of pulse groups within an epoch having chain and transmitter level dithering according to one or more examples.
• 6 illustrates transmitter-level dithering over time according to one or more examples.
• 7 illustrates masked dithering over time according to one or more examples.
• 8A is a graph illustrating a positive phase code pulse for an exemplary pulse according to one or more examples.
• 8B is a graph showing the exemplary pulse group containing positive phase code pulses (e.g. from 8A) and negative phase code pulses (e.g. from 8C ) includes.
• 8C is a graph illustrating a negative phase code pulse for an exemplary pulse group according to one or more examples.
• 9 illustrates a system for performing one or more disclosed techniques when generating radio waves (e.g., radio frequency ground waves) for pulses according to one or more examples.
• 10 is a functional block diagram illustrating logical blocks of a system for performing one or more disclosed techniques when generating high frequency ground waves for pulses, according to one or more examples.
• 11 is a flowchart illustrating a method according to one or more examples.
• 12A and 12B collectively include a flowchart of a method according to one or more examples.
• 13 is a flowchart of a method according to one or more examples.
• 14 is a flowchart of a method according to one or more examples.
• 15 is a flowchart of a method according to one or more examples.
• 16 is a functional block diagram illustrating a receiver according to one or more examples.
• 17 is a functional block diagram illustrating a system including a transmitter and a receiver, according to one or more examples.
• 18 is a functional block diagram illustrating one or more operations that may occur at a receiver according to one or more examples.
• 19 is a functional block diagram illustrating one or more operations that may occur at a receiver according to one or more examples.
• 20 is a flowchart illustrating a method for receiving radio waves and decoding data encoded by the radio waves, according to one or more examples.
• 21 is a flowchart illustrating a method for receiving radio waves and decoding data encoded by the radio waves, according to one or more examples.

MODE(S) FOR CARRYING OUT THE INVENTION

In the following detailed description, reference is made to the accompanying drawings, which form a part of this document, and in which is shown by way of illustration specific examples of examples in which the present disclosure may be practiced. These examples are described in sufficient detail to enable those skilled in the art to practice the present disclosure. However, other examples enabled herein may be utilized, and changes in structure, material, and process may be made without departing from the scope of the disclosure.

The illustrations presented herein are not intended to be actual views of any particular method or system or device or structure, but are merely idealized representations used to describe the examples. In some cases, similar structures or components may retain the same or similar numbering in the various drawings for the convenience of the reader; however, the similarity in numbering does not necessarily imply that the structures or components are identical in size, composition, configuration, or any other characteristic.

The following description may include examples to enable those skilled in the art to practice the disclosed examples. The use of the terms "exemplary," "as an example," and "for example" means that the associated description is explanatory, and although the scope of the disclosure is intended to include the examples and their legal equivalents, the use of these terms is not intended to limit the scope of an example of this disclosure to the specified components, steps, features, functions, or the like.

It is to be understood that the components of the examples, as generally described herein and illustrated in the drawings, can be arranged and configured in a variety of different configurations. Thus, the following description of various examples is not intended to limit the scope of the present disclosure, but is merely representative of various examples. While the various aspects of the examples may be illustrated in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

Furthermore, the specific implementations shown and described are only examples and should not be construed as the only way to implement the present disclosure, unless otherwise indicated herein. Elements, circuits, and functions may be shown in block diagram form in order not to obscure the present disclosure with unnecessary detail. In addition, block definitions and the partitioning of logic between various blocks are exemplary of a specific implementation. It will be readily apparent to those skilled in the art that the present disclosure may be practiced using numerous other partitioning solutions. Details of timing considerations and the like have been largely omitted to the extent that such details are not necessary for a complete understanding of the present disclosure and are within the capabilities of those skilled in the art.

One of ordinary skill in the art will understand that information and signals may be represented using a variety of different technologies and techniques. Some drawings may illustrate signals as a single signal for clarity of illustration and description. One of ordinary skill in the art will understand that the signal may represent a group of signals, where the group may have a variety of bit widths, and the present disclosure may be implemented on any number of data signals, including a single data signal.

The various illustrative logic blocks, modules, and circuits described in connection with the examples disclosed herein may be implemented or performed using a general purpose processor, a special purpose processor, a digital signal processor (DSP), an integrated circuit (IC), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor (which may also be referred to herein as a host processor or simply a host) may be a microprocessor, but alternatively may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. A general-purpose computer, including a processor, is considered a special-purpose computer, while the general-purpose computer is configured to execute computational instructions (e.g., software code, without limitation) related to examples.

The examples may be described with respect to a process represented as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe operational acts as a sequential process, many of these acts may be performed in a different order, in parallel, or substantially simultaneously. In addition, the order of the acts may be changed. A process may correspond to a method, a thread, a function, a procedure, a subroutine, a subprogram, other structure, or combinations thereof. Furthermore, the methods disclosed herein may be implemented in hardware, software, or both. When implemented in software, the functions may be stored or transmitted as one or more instructions or as code on computer-readable media. Computer-readable media includes both computer storage media and communications media, including any media that supports the transmission of a computer program from one location to another.

Any reference to an element herein using a label such as "first," "second," etc., does not limit the set or order of those elements unless such a limitation is expressly stated. Rather, these labels may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to a first and a second element does not imply that only two elements may be used therein or that the first element must precede the second element in any way. Furthermore, unless otherwise stated, a set of elements may include one or more elements.

As used herein, the term "substantially" with respect to a given parameter, property, or condition means and includes, to the extent understood by one of ordinary skill in the art, that the given parameter, property, or condition is satisfied with a small degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially satisfied, the parameter, property, or condition may be at least 90% satisfied, at least 95% satisfied, or even at least 99% satisfied.

LORAN ("Long Range Navigation" or just "Loran") signals, developed in the 1950s, are ranging signals from transmitted radio frequency (RF) ground waves at low frequencies, typically between 90 and 110 kilohertz (kHz), that can be used for positioning, navigation, and/or timing ("PNT"). These ranging signals can travel more than 1,000 miles through air, structures, land, and water, and can be up to 10,000 times stronger than, as a non-limiting example, Global Positioning System (GPS) signals. Loran technology (and in particular an intermediate technology referred to as "Loran-C") was improved in the 1990s, resulting in enhanced Loran (eLoran) navigation systems. Among other capabilities, eLoran navigation systems include transmitter locations synchronized to Coordinated Universal Time, the use of Time of Transmission (TOT) control instead of the System Area Monitor (SAM) control used by Loran navigation systems, and the addition of a Loran Data Channel (LDC) to a ranging signal to provide time, improved positioning accuracy, and increased integrity.

A typical transmission of an eLoran-type ranging signal is a pulse train of eLoran-type pulses of oscillating signals (e.g., pulses of oscillating signals, the pulses having an envelope associated with eLoran). A pulse envelope of each pulse includes a leading edge that starts at a first rest point (i.e., zero or negligible energy of the oscillating signal) and rises until a point of maximum amplitude (the "peak" of the pulse) is reached, followed by a trailing edge that starts at the peak and falls until it reaches a second rest point. In a conventional eLoran pulse, a portion of the pulse, substantially defined during part of the leading edge, is used for phase tracking (in conventional eLoran, this is typically the sixth zero crossing through the oscillating signal) to encode timing information into a pulse, and in particular for PNT. A receiver may use a positioning technique (including, as non-limiting examples, multilateral position estimation or hyperbolic position estimation calculations) to recover PNT information based on received eLoran-type ranging signals. Additionally, in some cases, eLoran signals may be used to encode data.

Transmitters in a conventional eLoran configuration known to the inventors of this disclosure may be hundreds and sometimes thousands of miles apart. Each transmitter may be hundreds of feet high (e.g., 625 feet above the local relative altitude.

Despite the capabilities of eLoran, funding for the implementation of an eLoran navigation system in the United States was reduced in the 2010s in favor of GPS systems, and today only a few radio towers remain.

The inventors of this disclosure believe there is a general over-dependence on GPS compared to PNT. The availability of low-cost GPS jammers and signal spoofers raises security concerns, particularly in critical infrastructure, key resources, and life-critical applications. Accordingly, industry and government agencies recognize a need for a complementary/replacement navigation system for GPS, or even an alternative, if not in all environments, then at least in some applications.

To provide a suitable replacement or alternative for GPS, the inventors of this disclosure estimate a need for access control for eLoran PNT services; support for different PNT services; an increased data transfer rate (compared to conventional eLoran) to provide additional one-way (i.e., unidirectional) communication capability; and improved immunity to jamming and spoofing attacks.

One or more examples generally relate to encoding data into phases of one or more pulses. For example, a data message may be encoded into the phases of a number of pulses of a pulse group. For example, a transmitter may transmit a pulse group that may include a number of pulses (e.g., ranging pulses) that may be used (by a receiver) to detect the signal and/or determine PNT information. The pulse group may additionally include a number of pulses that may be used by the transmitter to encode data (including, e.g., a message and/or timing information) (e.g., data pulses and/or timing pulses). A transmitter may encode the data in the data pulses into phases of the data signals. For example, the transmitter may selectively adjust the phases of the data signals to encode data.

Additionally or alternatively, one or more examples generally relate to encoding information indicative of a specific transmitter in a pulse group of a ranging signal. More specifically, one or more examples relate to encoding information indicative of a transmitter in an interpulse interval of the pulse group.

Additionally or alternatively, one or more examples generally relate to arranging information transmissions to reduce the impact of burst errors on a receiver, and in various examples more specifically according to an algorithm selected to improve the effectiveness of forward error correction (FEC) techniques, including those using Reed-Solomon FEC blocks for error correction.

Additionally or alternatively, one or more examples generally relate to transmitting ranging signals according to a pulse phase signature schedule known to certain recipients of the signal. As a non-limiting example, transmitting ranging signals according to the pulse phase signature schedule may at least partially combat attempts to spoof a ranging signal.

Additionally or alternatively, one or more examples relate to delaying transmission of ranging signals according to a dithering schedule such that receivers of the ranging signals may be limited in their ability to use the ranging signals without the dithering schedule. For example, PNT information calculated based on delayed ranging signals may be inaccurate. And conversely, a receiver in possession of the dithering schedule may be able to correct for the delays.

One or more examples generally relate to decoding data encoded phases of one or more pulses. For example, a data message may be encoded in the phases of a number of pulses of a pulse group. For example, a transmitter may transmit a pulse group that may include a number of pulses (e.g., ranging pulses) that may be used (by a receiver) to detect the signal and/or determine PNT information. The pulse group may additionally include a number of pulses that may be used by the transmitter to encode data (including, e.g., a message and/or timing information) (e.g., data pulses and/or timing pulses). A receiver may decode the data encoded in the data pulses into phases of the data signals. For example, the receiver may identify phases of the data pulses and translate the phases of the data pulses into data (e.g., the message and/or timing information).

Additionally or alternatively, one or more examples may generally relate to decoding information from a pulse group of a ranging signal. The information may indicate a specific transmitter, e.g., the transmitter that transmitted the ranging signal. Thus, one or more examples may relate to identifying a transmitter in response to information encoded in the pulse groups. More specifically, one or more examples may relate to identifying a transmitter in response to an interpulse interval (e.g., a nominal interpulse interval) of a pulse group. Identifying the transmitter may assist in calculating PNT information. Additionally or alternatively, identifying the transmitter may be useful for validating the ranging signals.

Additionally or alternatively, one or more examples relate to identifying pulses of epochs according to a pulse ordering scheme. The pulses may be arranged within an epoch of the ranging signal according to the pulse ordering scheme to, among other things, reduce the impact of burst errors.

Additionally or alternatively, one or more examples relate to validating a ranging signal by comparing phases of pulses of the ranging signal to a pulse phase signature. Validating the ranging signal may at least partially counteract attempts to spoof ranging signals.

Additionally or alternatively, one or more examples relate to correcting delays added to ranging signals. For example, ranging signals may have been delayed according to a dithering schedule. One or more examples relate to calculating transmission times of such location signals that take the delay into account. For example, one or more examples may use the dithering schedule to correct delays in ranging signals that were added to the ranging signals according to the dithering schedule.

While examples may be discussed herein in the context of eLoran PNT systems, one of ordinary skill in the art will recognize that this is only one example of an environment in which disclosed examples may be employed and implemented; and use in other environments does not exceed the scope of this disclosure.

As used herein, the term "ranging signal" means a signal provided (e.g., transmitted) by a transmitter that may be usable to determine PNT information. Additionally, as used herein, a "ranging signal" may be used to transmit data that includes timing information and/or a message. Thus, a ranging signal may include ranging signals to be used to determine distance and/or position information, data pulses to transmit data, and/or timing pulses to transmit timing information.

As used herein, the term "pulse group" means two or more signal pulses generated by a same transmitter. A ranging signal pulse (also referred to herein as a "ranging pulse," "data pulse," "data message pulse," "timing pulse," "time pulse," "time message pulse," "timing message pulse," and/or "pulse") is a non-limiting example of a pulse group signal pulse.

As used herein, “interpulse interval” means a period of time defined between the start (i.e., start time) of consecutive pulses of a pulse group.

As used herein, “group repetition interval” means a period of time defined between the start (i.e., start time) of successive groups of pulses from the same transmitter.

As used herein, the terms "transmit cycle" and "epoch" mean two or more pulse groups, not necessarily generated by the same transmitter. In some cases, the term "transmit cycle" may be used as a shorthand term to refer to the duration of a transmit cycle. A number of pulse groups per transmit cycle is typically defined in a specification. As a non-limiting example, in an eLoran-based system, the number of pulse groups per transmit cycle may be defined based on a number of desired bits for a message. In such a case, the number of pulse groups per transmit cycle is based on the number of pulse groups for a desired message.

1A illustrates exemplary pulse groups of an exemplary epoch 116 of a distance measurement signal according to one or more examples. For example, 1A two pulse groups (PGs) from three different transmitters (TXs) in epoch 116. 1A a first pulse group of a first transmitter, PG1 of TX1 102, a first pulse group of a second transmitter, PG1 of TX2 104, a first pulse group of a third transmitter, PG1 of TX3 106, a second pulse group of the first transmitter, PG2 of TX1 108, a second pulse group of the second transmitter, PG2 of TX2 110 and a second pulse group of the third transmitter, PG2 of TX3 112. Additionally illustrated 1A a first pulse group of a second epoch, PG1 from TX1 114. Although epoch 116 is illustrated as two pulse groups from each of three transmitters, an epoch may include any number of pulse groups from any number of transmitters.

A duration of an epoch 116 generally corresponds to a time during which pulse groups (e.g., PG1 from TX1 102, PG1 from TX2 104, PG1 from TX3 106, PG2 from TX1 108, PG2 from TX2 110, PG2 from TX3 112, and additional pulse groups (e.g., from the first, second, and third transmitters)) are transmitted. The duration of an epoch, such as epoch 116, may refer to a desired number of pulse groups per epoch and a number of transmitters per geographic area or group of transmitters (which may be referred to in the art as a "chain"). As indicated by 1A As illustrated, epoch 116 is defined by a "beginning" at a start 122 of epoch 116 (or by a nominal start time as discussed below) and an "end" at a start of a second epoch 124 (or by a nominal start of a next epoch as discussed below). An end of an epoch corresponds to a start of a subsequent epoch, and so on and so forth.

1A illustrates two example group repetition intervals: The TX1 group repetition interval 118 is defined between the start of a first pulse group of a first transmitter (e.g., PG1 of TX1 102) and the start of a second pulse group of the first transmitter (e.g., PG2 of TX1 108). The TX3 group repetition interval 120 is defined between the start of a first pulse group of a third transmitter (e.g., PG1 of TX3 106) and the start of a second pulse group of the third transmitter (e.g., PG2 of TX3 112).

1A illustrates a nominal emission delay 154, that is, a time period between the start of a first pulse group and the start of an immediately following pulse group, which may be from a different transmitter. For example, the nominal emission delay 154 is the time period between the start of PG1 from TX2 and the start of PG1 from TX3.

In particular, any suitable markers may be used to define a group repetition interval or nominal emission delay without exceeding the scope of this disclosure, such as peaks, start of leading edges, prespecified zero crossings, or combinations thereof, without limitation. As non-limiting examples, peaks of first or last pulses of the respective pulse groups, a start of a leading edge of the first or last pulses of the respective pulse groups, prespecified zero crossings of oscillating signals of the first or last pulses of the respective pulse groups, and combinations thereof may be used to define the group repetition interval or nominal emission delay. Unless otherwise specified, the marker used to define intervals in examples is the start of the leading edge of the pulses of interest. In some cases, an end of a trailing edge cannot be used as a marker because the trailing end may be tapered.

1B illustrates pulses P1 through PN of a pulse group 152 of a distance measurement signal according to one or more examples. In In one or more examples, the interpulse interval 128 may be an interval between consecutive pulses of the pulse group 152. The interpulse interval 128 may be 140 microseconds or more. In some examples, a transmitter may use a unique (or unique within a geographic area) interpulse interval. Thus, in some examples, an interpulse interval 128 may be used to identify a transmitter that transmitted a respective pulse group. In other words, in some examples, the duration of an interpulse interval 128 may encode a transmitter identification into a pulse group. In particular, any suitable markers may be used to define the interpulse interval 128 without exceeding the scope of this disclosure, including, by way of non-limiting examples, start times, peaks, an end of a trailing edge, a start of a leading edge, prespecified zero crossings of oscillating signals, and combinations thereof.

1B illustrates pulses that may be part of one of the pulse groups discussed herein, such as PG1 of TX1 102, illustrated in 1A , without limitation. This disclosure is not limited to the 1B The use of other forms of pulse envelopes, such as the one shown by 1C The shape of the impulse envelope illustrated, without limitation, is specifically contemplated and does not exceed the scope of this disclosure.

Pulse group 152 includes 105 pulses, each occupying 140 microseconds or more of time. The first 63 pulses 124 of each pulse group 152 may be used to detect the signal. The last 42 pulses 125 may be used to encode the time and data message. The last 42 pulses 125 may be divided into 6 sets of 7 pulses, with 140 microseconds or more of non-transmission (e.g., a pulse length delay 126 during which the transmitter does not transmit) between each set. Further, in some examples, the first 63 pulses 124 may be separated from the last 42 pulses 125 by pulse length delay 126. The total length of a transmission may be (105 pulses + 6 pulse length delays) * 140 microseconds, or 15.54 milliseconds or more for longer pulse intervals.

In various examples, the set of phases of the first 63 pulses of each pulse group of a first transmitter (e.g., TX1) may be different from the set of phases of the first 63 pulses of each pulse group of a different transmitter (e.g., TX3). For example, the set of phases of the first 63 pulses of each pulse group may be indicative of the transmitter from which the pulse group originates. For example, the set of phases of the first 63 pulses 124 of each pulse group of TX1 may be unique (or unique within a geographic range) to TX1, and the set of phases of the first 63 pulses of each pulse group of TX3 may be unique (or within a geographic range) to TX3. Thus, the set of phases of the first 63 pulses of each pulse group may be indicative of the transmitter from which the pulse group originates. Further details regarding pulse phase encoding are provided with respect to 1C, 1D and 8A to 8C specified.

In various examples, the set of phases of the first 63 pulses of each pulse group of each transmitter may vary from epoch to epoch. Varying the set of phases of the first 63 pulses of each epoch can make spoofing more difficult.

In various examples, the last 42 pulses 125 may be used to encode a time and/or a data message. As a non-limiting example, the last 42 pulses 125 may be divided into six sets of seven pulses, with a respective pulse length delay 126 between each set of seven pulses. The phases of each of the seven pulses of each set may represent a 6-bit symbol (or in some examples, a 7-bit symbol) for data encoding. The time and data message may be transmitted over an epoch using 420 pulses. The time message may be transmitted using 84 of the 420 pulses. The time message may be encoded using a Reed-Solomon FEC code using 6-bit symbols, six data symbols, and six parity symbols (twelve symbols total). The data message may be transmitted using 336 of the 420 pulses. The data message can be encoded using a Reed-Solomon FEC code, using 6-bit symbols, 22 data symbols and 26 parity symbols (48 symbols total).

1B illustrates a pulse group duration 123, which is a period of time between the start of the first pulse of a pulse group (e.g. start of pulse group 130) and the start of the first pulse of a next pulse group (in 1B not illustrated) (e.g. end of pulse group 132).

The information in relation to 1B The time periods illustrated and described are given as non-limiting examples. Furthermore, the total number of pulses, the number of first pulses 124 (or pulses that are used to capture the signal), the number of last pulses 125 (or pulses used to encode data), the number of sets of pulses used to encode data, and the number of pulses in each set are non-limiting examples.

1C illustrates pulse 148 of a ranging signal according to one or more examples. Pulse 148 may be encoded with timing information, e.g., a point in the pulse may indicate a timing event. As a non-limiting example, the sixth zero crossing (e.g., zero crossing 140) may be used by a receiver as an indication of a timing event, e.g., for positioning, navigation, and timing for a positioning technique (including, as non-limiting examples, multilateral or hyperbolic position estimation calculations).

1C further illustrates a pulse start point 136, which may be a time at which the pulse 148 begins, e.g., moving either positively or negatively from a rest point. 1C also illustrates the pulse end point 138, which may be the time at which the pulse 148 ends, e.g., returns to a stable resting state. Together, the pulse start point 136 and the pulse end point 138 define a pulse duration 134 of the pulse 148. Alternatively, since transmissions after some point in the pulse 148 may include ringing, the pulse end point 138 may be defined as a pulse duration 134 after the pulse start point 136. 1C further illustrates pulse amplitude 142, which may be the amplitude of pulse 148 from a negative peak to a positive peak.

1D illustrates another exemplary pulse 158 according to one or more examples. Pulses may be binary encoded with phase codes. For example, pulse 148 may be 1C a + 1 encode, and pulse 158 from 1D can encode -1 because pulse 158 can have the opposite phase to pulse 148. Further details regarding pulse phase encoding are given in relation to 8A to 8C given.

2 illustrates a pulse ordering scheme 200 for encoding the time and data messages according to one or more examples. For example, 2 an exemplary allocation of six sets of seven pulses that are used to encode the messages in a pulse group. In 2 10 pulse groups (e.g., an epoch) are illustrated. Each of the illustrated sets of seven pulses is assigned as either a time message pulse set or a data message pulse set. Varying the arrangement within an epoch can reduce the impact of burst errors on data transmission and, in particular, improve the performance of forward error correction techniques. The allocation schemes can be selected according to any suitable algorithm, as a non-limiting example, according to an algorithm that improves the performance of a Reed-Solomon type of FEC blocks.

2 illustrates two different data types that can be encoded in the 42 pulses used for data encoding according to one or more examples (e.g., the last 42 pulses 125 of 1B) As a non-limiting example, 2 Time message pulse sets ("T") and data message pulse sets ("D"). The use of fewer types of pulses or other types of pulses, in addition to or alternatively to those discussed herein, does not exceed the scope of this disclosure.

As mentioned above with respect to 1B As described, the first 63 ranging pulses 124 of a pulse group at a receiver may be used to extract one or more times of arrival of one or more of the pulses, which may be used, for example, to determine position information of a receiver. For example, in some examples, an average time of arrival may be determined for all of the first 63 ranging pulses.

Timing message pulses (which may alternatively be referred to herein as "timing pulses") may collectively encode the timing information. As a non-limiting example, a transmitter may be configured to maintain a count of epochs, e.g., as an "epoch number," and may transmit the epoch number encoded in the timing message pulses of each epoch. The timing message pulses may include one or more error correction bits, e.g., according to a Reed-Solomon error correction scheme. As an example of encoding timing information, the epoch number may be a 32-bit number, and the 84 timing message pulses of an epoch may collectively encode the epoch number and the one or more error correction bits. For example, the 84 timing message pulses encode 12 six-bit symbols. Of these, six symbols (36 bits) are used to encode the timing information, and six symbols (36 bits) are used for error correction.

Data message pulses (which may alternatively be referred to herein as “data pulses”) may collectively encode a data message. Data message pulses may communicate a message, e.g., from a system operator of a Loran system to a Loran receiver or to a user of a Loran receiver. Non-limiting examples of information carried via data message pulses include differential corrections, almanac information for transmitters and differential monitors, or messages including, as non-limiting examples, emergency alerts or weather warnings. The data message pulses may further include one or more error correction message pulses, e.g., an FEC block according to a Reed-Solomon error correction scheme. For example, the 336 data message pulses encode 48 six-bit symbols. Of these, 22 symbols (132 bits) are used to encode the data message, and 26 symbols (156 bits) are used for error correction.

As a non-limiting example, 2 ten pulse groups 202, each of which includes six pulse sets 204. This illustrates 2 60 pulse set positions of an epoch. A "pulse set" can refer to seven pulses encoding six bits of information, for example in the last 42 pulses of a pulse group.

During an epoch, a transmitter may transmit the epoch's encoded pulse sets according to a pulse set ordering scheme, such as pulse set ordering scheme 200. By arranging the different types of pulse sets 206 according to pulse set ordering scheme 200, a receiver may be able to determine which pulses are of which type.

In various examples, the epoch number may be encoded in time message pulses or data in the data message pulses. For example, the epoch number encoded in the time message pulses may be encrypted prior to encoding. As another example, the data message encoded in the data message pulse sets may be encrypted prior to encoding. A single encrypted data message may span one or more epochs. The encryption of the epoch number or the data message may be such that the epoch number or the data message may be indecipherable without an encryption key. Thus, a receiver of all pulse sets of an epoch and in possession of the pulse set ordering scheme 200 but not in possession of the encryption key may be able to recover the symbols encoded by the time message pulses or the data message pulses, but may not be able to decrypt the epoch number or the data.

Alternatively, in various examples, the timing information may not be encrypted, e.g., the timing information may be transmitted unencrypted. Encrypting the timing information may enable a recipient of the timing message burst sets to obtain timing information, e.g., an epoch number, without possessing an encryption key. Enabling a recipient to obtain the epoch number without an encryption key may enable the recipient to obtain information (e.g., more accurate timing information by correcting dithering, which is described in more detail below).

However, transmitting the timing information in unencrypted form may leave the timing information vulnerable to spoofing. In various examples, the timing information may be transmitted unencrypted (e.g., in timing message bursts), and second timing information may be transmitted encrypted in data message bursts. The second timing information may be encrypted and thus less vulnerable to spoofing than the timing information transmitted unencrypted.

Furthermore, the second timing information may include additional timing information not included in the first timing information, e.g., a leap second count. Including the additional timing information in the second timing information may allow receivers in possession of the encryption key to obtain more detailed or accurate timing information than is possible for receivers not in possession of the encryption key. Furthermore, including the additional timing information in the second timing information may allow the timing information of the timing message pulses to not include the additional timing information, which may allow for reducing the number of timing message pulses or including additional error correction bits in the timing message pulses.

Additionally or alternatively, one or more examples generally relate to controlling the usability of positioning signals to limit precise use of the positioning signals to certain receivers by adding a time offset (referred to as a “dither offset,” “dithering offset,” or just “dithering”), which a specific receiver can correct with a dither correction before using the positioning signals. As a non-limiting example, the usability control can facilitate the assignment of the positioning signals and a navigation system using them.

3 is a timing diagram 300 illustrating example timings of pulse groups having dithering, according to one or more examples. In particular, 3 Timings of pulse groups of three epochs (epoch 1, epoch 2, and epoch 3). The pulse groups occurring during epoch 1 are not dithered, e.g., with respect to a nominal epoch start time 302A. (In the present disclosure, pulse groups occurring during an epoch may be referred to as "epoch" pulse groups.) The pulse groups of epoch 2 are delayed with respect to a nominal epoch start time 302B, and the pulse groups of epoch 3 are pre-dithered with respect to the nominal epoch start time 302C.

3 illustrates nominal epoch start times 302 (including nominal epoch start time 302A, which may be the nominal start time of epoch 1, nominal epoch start time 302B, which may be the nominal start time of epoch 2, and nominal epoch start time 302C, which may be the nominal start time of epoch 3). Nominal epoch start time 302A, nominal epoch start time 302B, and nominal epoch start time 302A may be collectively referred to as nominal epoch start times 302. 3 also illustrates nominal subsequent epoch start times 320 (including nominal subsequent epoch start time 320A, which may be the end of epoch 1 and the start time of a subsequent epoch, nominal subsequent epoch start time 320B, which may be the end of epoch 2 and the start time of a subsequent epoch, and nominal subsequent epoch start time 320C, which may be the end of epoch 3 and the start time of a subsequent epoch). Nominal subsequent epoch start time 320A, nominal subsequent epoch start time 320B, and nominal subsequent epoch start time 320C may collectively be referred to as nominal subsequent epoch start times 320. In various examples, epochs 1, 2, and 3 may be sequential or non-sequential. In other words, epoch 2 may or may not follow epoch 1. The nominal subsequent epoch start times 320 may follow the nominal epoch start times 302 by an epoch duration 306 (i.e., the duration of an epoch). A nominal subsequent epoch start time may be the end of a previous epoch. A nominal start time of an epoch may be the nominal subsequent epoch start time of the previous epoch. For example, if Epoch 2 followed Epoch 1, the nominal start time 302B would be a nominal subsequent start time 320A.

The pulse groups of epoch 1 are illustrated without dithering. For example, the first transmitter's first pulse group ("PG1 of TX1") is illustrated as starting at the nominal epoch start time 302A, i.e., PG1 of TX1 has not been smeared (not delayed or pre-sequenced) from the nominal epoch start time 302A. The first transmitter's second pulse group ("PG2 of TX1") begins at the group repeat interval 310 after the nominal epoch start time 302A. Additionally, the second transmitter's first pulse group ("PG1 of TX2") begins at the nominal second pulse group 304A, i.e., PG1 of TX2 has not been smeared from the nominal second pulse group start time 304A. Additionally, PG2 of TX2 begins at the group repeat interval 314 after the nominal second pulse group start time 304A. In various examples, group repeat interval 310 may have the same or a different duration than group repeat interval 314.

The pulse groups of epoch 2 are delayed by delay offset 312 from the nominal epoch start time 302B. For example, PG1 of TX1 of epoch 2 is delayed by delay offset 312 from the nominal epoch start time 302B. Similarly, PG1 of TX2 of epoch 2 is delayed from the nominal second pulse group start time 304B by delay offset 312. Likewise, all pulse groups of epoch 2 are delayed by delay offset 312. The timing of the pulse groups (e.g., smudged or not smudged) applies equally to all pulses of the pulse groups. For example, all pulses of PG1 of TX1 of epoch 2 are delayed by delay offset 312. Despite the delay of epoch 2, a subsequent epoch begins at the nominal subsequent epoch start time 320B rather than at the nominal subsequent epoch start time 320B plus delay offset 312. To prevent pulses from different epochs from being transmitted at the same time, in various examples, delay offset 312 may be selected to be shorter than a nominal duration between the end of a last pulse of a last pulse group of an epoch and the start of a first pulse of a first pulse group of a subsequent epoch.

The pulse groups of epoch 3 are pre-queued by the pre-queuing offset 318. For example, PG1 of TX1 of epoch 3 is pre-queued by the nominal epoch start time 302C by the pre-sequence offset 318. Similarly, PG1 of TX2 of epoch 3 is pre-sequenced from the nominal second pulse group start time 304C by the pre-sequence offset 318. Likewise, all pulse groups of epoch 3 are pre-sequenced by the pre-sequence offset 318. Despite this pre-sequencing, a subsequent epoch would nominally begin at the nominal subsequent epoch start time 320C and not after the nominal subsequent epoch start time 320C minus the pre-sequence offset 318. To prevent pulses from different epochs from being transmitted at the same time, in various examples, the pre-sequence offset 318 may be selected to be shorter than one-half of the nominal duration between the end of a last pulse of a last pulse group of an epoch and the start of a first pulse of a first pulse group of a subsequent epoch.

The term "chain-level dithering interval" may refer to a time interval by which all pulses of all pulse groups of all transmitters in a group of transmitters (which may be referred to as a chain) are delayed or pre-queued (relative to a nominal timing). A chain-level dithering interval (e.g., delay offset 312 or pre-queuing offset 318) may apply for the duration of an epoch. In subsequent epochs, the pulse groups of all transmitters in a group of transmitters may be delayed or pre-queued by a different chain-level dithering interval or not at all. Chain-level dithering is the dithering of a chain of transmitters by a chain-level dithering interval over an epoch.

As an example of dithering, 4 the dither offsets 400 of the emission delay of three transmitters in a chain over time. For example, 4 a first emission delay 402 of a first transmitter of a chain, a second emission delay 404 of a second transmitter of the chain, and a third emission delay 406 of a third transmitter of the chain. Dither offsets 400 (including the first emission delay 402, the second emission delay 404, and the third emission delay 406) may include offsets resulting from chain-level dithering, transmitter-level dithering, and masked dithering. Due to differences in size between chain-level dithering and transmitter-level dithering, and between chain-level dithering and masked dithering, 4 However, dithering at the transmitter level and masked dithering are not visible. 4 scaled to illustrate chain-level dithering in particular. (Sender-level dithering and masked dithering are discussed in more detail below.)

The third emission delay 406 is delayed relative to the second emission delay 404 by a nominal emission delay (e.g., 20,000 microseconds). Similarly, the second emission delay 404 is delayed relative to the first emission delay 402 by the nominal emission delay. 4 illustrates that each of the first emission delay 402, the second emission delay 404, and the third emission delay 406 are substantially parallel. The first emission delay 402, the second emission delay 404, and the third emission delay 406 are substantially parallel because each of the first emission delay 402, the second emission delay 404, and the third emission delay 406 are delayed by the same chain-level dithering interval in each epoch.

In various examples, a change in the dithering of a chain (i.e., a change in the dithering of all pulses of all pulse groups transmitted by a chain of transmitters) can follow over time. For example, 4 Changes in the dithering of the chain following a ramp pattern between multiple points (e.g., pseudorandomly selected points). For example, chain-level dithering, represented by dithering offsets 400, may have multiple random values and may follow a ramp between the multiple random values. Thus, in the 4 illustrated example, the change in dithering between any two epochs may be small relative to a change over many (e.g., 50,000 epochs). For example, at epoch 1, the chain dithering may be 0 microseconds, at epoch 2, the chain dithering may be slightly longer (e.g., 0.4 microseconds longer), and at epoch 50,000, the chain dithering may be 20,000 microseconds. Thus, the magnitude of chain-level dithering may be on the order of tens of thousands of microseconds when considered over many epochs, while the magnitude of change between any two epochs may be much smaller (e.g., 1 microsecond or less).

In addition to chain-level dithering, individual transmitters can dither the timing of pulse groups individually. For example, 5 Dithering at transmitter level and dithering at chain level. Dithering at transmitter level can be analogous to dithering at chain level in that dithering at transmitter level can include dithering of all pulses of all pulse groups for an epoch. In contrast to However, unlike chain-level dithering, transmitter-level dithering can be applied by transmitters individually and not by a chain of transmitters together.

5 illustrates an Epoch 4 that includes both chain-level dithering and sender-level dithering. 5 illustrates a nominal epoch start time 502. 5 illustrates a chain-level dithering interval 504 that pre-queues all pulse groups (including, e.g., PG1 of TX1, PG1 of TX2, PGN of TX1, and PGN of TX2) of a chain (e.g., TX1 and TX2) for the duration of epoch 4. That is, based on the chain-level dithering interval, the first pulse of epoch 4 (PG1 of TX1) would begin at the chain-level dithered start time 510, which is pre-queued from the nominal epoch start time 502 by the chain-level dithering interval 504.

5 However, illustrates that PG1 of TX1 is additionally delayed by the delay offset at transmitter level 506. For example, during epoch 4, TX1 delays all pulse groups by the delay offset at transmitter level 506.

It also illustrates 5 that the pulse groups of TX2 are pre-queued by the pre-queuing offset at transmitter level 508 (e.g., relative to the second pulse group start time 512 smeared at chain level). The delay offset at transmitter level 506 is independent of the pre-queuing offset at transmitter level 508.

The term "transmitter-level dithering interval" may be a time interval by which all pulse groups of a particular transmitter are delayed or advanced (relative to a nominal time or relative to a nominal time and a chain-level dithering). A transmitter-level dithering interval may apply for the duration of an epoch. In subsequent epochs, the pulse groups of the particular transmitter may be delayed or advanced by a different chain-level dithering interval. In some cases, all pulse groups of each transmitter of each epoch may be delayed by a different transmitter-level dithering interval or by a non-transmitter-level dithering interval. As an example of using a different transmitter-level dithering interval in each epoch, 6 Dither offsets 602 the emission delay of a 1st transmitter, for example in epochs 1 to 900. Transmitter level dithering is the dithering of a particular transmitter by a transmitter level dithering interval over an epoch.

As an example of dithering, 6 the dither offsets 602 of the emission delay of a transmitter over time. Other offsets 602 may include offsets resulting from chain-level dithering, transmitter-level dithering, and masked dithering. Due to differences in size between transmitter-level dithering and chain-level dithering, 6 However, chain-level dithering appears to be a general trend. Furthermore, due to the difference between sender-level dithering and masked dithering, masked dithering in 6 not recognizable. Thus, 6 particularly scaled to illustrate dithering at the transmitter level. For example, the uptrend from a 0-microsecond delay to a 200-microsecond delay that occurs between the 0th epoch and the 900th epoch may be a result of chain-level dithering (e.g. the 4 chain-level dithering). In particular, dither offsets 602, as shown in 6 illustrates a scaled view of the first emission delay 402 of 4 (Chain-level dithering is discussed in more detail above, and masked dithering is discussed in more detail below.) In the deviations, transmitter-level dithering can be observed in what would otherwise be a straight line from the 0 microsecond delay to the 200+ microsecond delay that occurs between the 0th epoch and the 900th epoch.

In various examples, a change in dithering of a transmitter (i.e., a change in dithering of all pulses of all pulse groups transmitted by a transmitter) may follow a trend over time. For example, the dithering offsets 602 may have multiple random values and may follow a ramp between the multiple random values. For example, 6 Changes in the dithering of the transmitter according to a ramp pattern between several points. Thus, in the 6 In the example illustrated, the change in dithering between any two epochs may be small relative to a change over many (e.g., 50 corresponding epochs). For example, in the 300th epoch, the transmitter dithering may be a delay of 60 microseconds, in the 301st epoch, the transmitter dithering may be a slightly longer delay (e.g., 1 microsecond longer), and in the 350th epoch, the transmitter dithering may be a delay of 110 microseconds. Thus, the magnitude of dithering at the transmitter level may be on the order of tens or hundreds of microseconds when many epochs are considered, while the magnitude of the change between any two adjacent ten epochs can be much smaller (e.g. 1 microsecond or less).

Additionally, in various examples, a magnitude of change caused by a chain-level dithering interval over time may be larger or smaller (e.g., by an order of magnitude or more) than a magnitude of change caused by a transmitter-level dithering interval over the same time period. For example, a magnitude of change caused by the dither offsets 400 of 4 be one hundred times greater than the magnitude of the change caused by dither offsets 602 of 6 Put another way, in terms of overall dithering over time, chain-level dithering may affect an instantaneous dither, i.e., the dither between two subsequent epochs, 100 times more than transmitter-level dithering affects the instantaneous dither. For example, transmitter-level dithering may account for variations in dither offsets 602 that are on the order of tens of microseconds over the course of epochs 1 to 900, while chain-level dithering may account for the overall trend of dither offsets 602 (e.g., between zero microseconds to over 200 microseconds) over the course of epochs 1 to 900.

Additionally, in various examples, the duration of a ramp of the chain-level dithering may differ from a duration of a ramp of the transmitter-level dithering interval (e.g., by an order of magnitude or more). For example, chain-level dither offsets (where the chain-level dither offsets are in 4 specially scaled for illustration purposes) follow a ramp between two values for a duration of 30,000 epochs, while the transmitter-level dither offsets (where the transmitter-level dither offsets are in 6 specially scaled for illustration purposes) can follow a ramp between two values for a duration of 60 respective epochs.

The size of the chain-level dithering interval or the transmitter-level dithering interval can be chosen to be smaller than a standard duration between pulse groups (or epochs). For example, the chain-level dithering interval and the transmitter-level dithering interval can be chosen such that even if a chain and transmitter were delayed during a first epoch and the chain and transmitter were pre-queued during the next epoch, overlap of pulse groups is avoided. As another example, the transmitter-level dithering interval can be chosen such that if pulses from a first transmitter were delayed and pulses from a second transmitter were pre-queued, signals from the first and second transmitters would not overlap.

By dithering one or more pulse groups during one or more epochs (e.g. as by 3 and 5 illustrated), it may be possible to privatize the signals of a system (e.g., a time-dependent system). As a non-limiting example, receivers may depend on timing (e.g., the time of arrival of signals at the receiver) to calculate positioning, navigation, and timing information. If signals transmitted at one or more transmitters are dithered, the receiver may not be able to accurately calculate positioning, navigation, and timing information. In other words, dithering may introduce errors into the positioning, navigation, and timing information that can be calculated at a receiver.

In various examples, one or more of the transmitters may dither signals according to a dithering schedule. The dithering schedule may include a predefined dithering schedule that is a schedule of dithering intervals (e.g., chain-level dithering intervals or transmitter-level dithering intervals) to be applied to signals transmitted during a number of epochs. A receiver in possession of the dithering schedule may be able to correct for the effects of dithering on the received signals and thereby accurately calculate the positioning, navigation, and timing information. Receivers without the dithering schedule may not be able to accurately calculate the positioning, navigation, and timing information from the dithered signals.

Broadcasters or chains may privatize their signals, e.g. by having precise use of the signals dependent on ownership of the dithering schedule. An operator of the broadcasters may sell the dithering schedule, e.g. on a subscription basis.

In one or more examples, multiple service tiers may be defined to allow for different levels of accuracy that can be computed at a receiver. As a non-limiting example, senders may include two or more dithering instances and sell the dithering schedules separately. Additionally or alternatively, dithering schedules including different levels of accuracy may be sold. Specific users receive two keys and lower level users a single key. The dither could be the sum of two terms, specific users would have access to both terms (via their keys), and lower-level users can only access a coarse term (via their key).

The dithering schedule may be encrypted or used only with a key, so that a receiver must possess a key to utilize the dithering schedule. Dithering on a chain or transmitter may be related to the epoch number. As a non-limiting example, the dithering schedule may include dithering intervals for each epoch number. Thus, the dithering schedule may be indexable by the epoch number. As an example, the dithering schedule may include a function (e.g., an encryption algorithm) that may take as input the key and the epoch number and return corrections to the dithering for one or more transmitters for that epoch. A receiver may use the corrections to correct pulses received during the epoch. Thus, possession of both the epoch number and the key may be critical to accurately computing PNT information.

In various examples, the amount of chain-level dithering and/or transmitter-level dithering may be selected according to a ramp such that a receiver may be able to decode an epoch number of transmissions without fully correcting the dithering. For example, a amount of chain-level dithering or transmitter-level dithering may be chosen to be large enough to inaccurately reflect location calculations, but at the same time, due to the ramp and the relatively small difference between the dithering of individual pulse groups, a receiver may be able to decode an epoch number from the transmit cycle. Thus, during initialization of a receiver, the receiver may be able to obtain an epoch number that may then be used with the dithering schedule to correct the pulses. Additionally or alternatively, the ramps in the amounts of chain-level dithering or transmitter-level dithering may prevent or make it difficult to resolve the dithering by averaging over epochs. For example, if dithering were random at the transmitter level, in each epoch with a mean of zero, each receiver could observe a number of epochs and average the dithering.

In addition to chain-level dithering and/or sender-level dithering, masked dithering may be applied in various examples. Masked dithering may be used to mask trends in dithering. In particular, in cases where chain-level dithering and/or sender-level dithering is applied according to a ramp, masked dithering may obscure the one or more ramps and/or make dithering difficult or unlikely to predict.

In particular, masked dithering may include pseudorandom dithering applied to pulse groups (including all pulses of the pulse group) independently of each epoch. Masked dithering may use different amounts of dithering independent of the dithering of previous epochs. For example, unlike dithering that follows a ramp, masked dithering may be independent of each epoch. Thus, the offset resulting from masked dithering may differ relatively large between one epoch and the next compared to the offset resulting from masked dithering over many epochs. The relatively high difference between the offsets of subsequent epochs of masked dithering may mask the effects of chain-level dithering and/or transmitter-level dithering, which may follow a ramp. For example, in the absence of masked dithering, a receiver, e.g. For example, a receiver that is not in possession of the dithering schedule may be able to observe the ramp of chain-level dithering and/or transmitter-level dithering over time and (assuming chain-level dithering and/or transmitter-level dithering follow the ramp) predict the dithering of future pulse groups. However, with masked dithering applied, a receiver is less able to observe the ramp of either chain-level dithering or transmitter-level dithering (in other words, it may take longer for a receiver to be able to observe the ramps of chain-level dithering and/or transmitter-level dithering).

As an example of dithering, 7 Dither offsets 702 of the emission delay of a transmitter over time. Dither offsets 702 may include offsets resulting from chain-level dithering, transmitter-level dithering, and masked dithering. However, due to differences in size between masked dithering and chain-level dithering and between masked dithering and transmitter-level dithering, 7 Dithering at chain level and/or dithering at transmitter level appear as a general trend. clearly 7 especially masked dithering. For example, from the 200th epoch to the 250th epoch of 7 the general upward trend (e.g., from an offset of 70.8 microseconds to an offset of 71.7 microseconds after 50 respective epochs) may be a result of chain-level dithering and/or transmitter-level dithering. Thus, dither offsets 702 as shown in 7 illustrates a scaled view of the first emission delay 402 of 4 and a scaled view of dither offsets 602 of 6 be.

Unlike ramped dithering (such as can be applied in chain-level dithering and/or transmitter-level dithering by using a ramp), masked dithering is applied independently of each epoch. The masked dither can be a pseudorandom dither (with a mean of zero). However, because the masked dither is independent of each epoch, the masked dither does not cause a trend in the dither over time.

In various examples, masked dithering can change the timing of pulse groups by magnitudes (of timing) that are smaller or larger than (e.g., by an order of magnitude or more) the chain-level dithering interval or the transmitter-level dithering interval. For example, as in 7 As illustrated, masked dithering can blur a signal on the order of 0.2 microseconds. However, because masked dither has a zero mean, masked dithering does not cause a trend over time. In other words, masked dithering can cause a 0.2 microsecond swing between the 1st epoch and the 2nd epoch, and masked dithering can cause a 0.2 microsecond swing between the 1st epoch and the 300th epoch or the 50,000th epoch. In other words, the amount of masked dithering can be the same whether many epochs or single epochs are considered.

As with chain-level dithering and transmitter-level dithering, masked dithering can be included in the dithering schedule so that the masked dithering can be corrected for (e.g., by a receiver in possession of the dithering schedule) before positioning, navigation, and timing information is computed from the smeared signals.

Additionally or alternatively, one or more examples generally relate to providing validation of pulse groups by encoding a signature in phases of pulses of pulse groups.

8A , 8B and 8C illustrate graphs depicting phase encoding of a pulse group 800 according to one or more examples.

8A illustrates a graph depicting a positive phase code pulse for an exemplary pulse group 800, and may include an expanded view of the beginning of pulse 148 of 1C be. 8C illustrates a graph depicting a negative phase code pulse for the exemplary pulse group 800 and may include an expanded view of the beginning of pulse 158 of 1D A pulse, e.g., the positive phase code pulse 802, may include multiple positive half cycles 804 and multiple negative half cycles 806. A pulse may have a positive phase code, e.g., as illustrated by the positive phase code pulse 802, or a negative phase code, e.g., as illustrated by the negative phase code pulse 808 ( 8C ). As a non-limiting example, the positive phase code pulse 802 may begin with one of the positive half cycles 804 of the carrier, and the negative phase code pulse 808 may begin with one of the negative half cycles 806 of the carrier. The negative phase code pulse 808 may be offset by 180 degrees from the phase of the positive phase code pulse 802.

The zero crossings of the positive phase code pulse 802 and the negative phase code pulse 808 may be the same, which may be relevant for timing, e.g., for positioning, navigation, or timing. Furthermore, the frequency (or frequencies) of the positive phase code pulse 802 and the negative phase code pulse 808 may be the same.

8B illustrates a pulse group 800 that includes positive phase code pulses 810 and negative phase code pulses 812. Accordingly, the phases of some or all of the pulses in the pulse group may be used together to encode information (e.g., a transmitter signature, timing information, or data message). Regardless of whether each of the pulses of the pulse group 800 is a positive phase code pulse or a negative phase code pulse, they may, for example, encode a bit of data encoding information. The encoding information in the phases of pulses of a pulse group may not affect timing or other data encoding included in the pulse group. As discussed above with respect to 1B As described, one or more subsets of pulses in a pulse group may be phase-encoded. For example, distance measurement pulses (e.g. the first 63 pulses 124 of 1B) encode a signature that is unique to a transmitter, timing pulses (e.g. some of the last 42 Impulses 125 of 1B) can encode timing information, and data pulses (e.g. some of the last 42 pulses 125 of 1B) can encode a data message.

Phases of pulses of a pulse group can be used to enable validation of a signal (and consequently data) and to increase the security of a system. For example, phases of pulses of a pulse group can be encoded to prevent (or make more difficult) spoofing of a signal from a transmitter of the system. In other words, a system can use phase encoding for anti-spoofing purposes.

As a non-limiting example, a transmitter may comprise pulses of pulse groups such that the transmitted pulse groups match a pulse phase signature. The transmitter may change pulse phase signatures each epoch according to a pulse phase signature schedule. As a non-limiting example, a transmitter may transmit a first pulse group matching a first pulse phase signature in a first epoch according to the pulse phase signature schedule and transmit a second pulse group matching a second pulse phase signature in a second epoch according to the pulse phase signature schedule.

A receiver, in possession of the pulse phase signature plan, may be able to verify that the transmitter is transmitting the signal, e.g., by comparing phases of the received pulse groups to the pulse phase signature plan. Further, the pulse phase signature plan may be related to the epoch number. As a non-limiting example, the pulse phase signature plan may include pulse phase signatures WSP by the epoch number.

The pulse phase signature plan may be encrypted such that a receiver must possess a key to use the pulse phase signature plan. As an example, the pulse phase signature plan may include a function that can accept as input the key and the epoch number and return an expected pulse phase signature for the epoch. A receiver may compare received pulse phases with the expected pulse phase signature to authenticate the received signal.

9 is a functional block diagram illustrating an example of logical blocks of a system 900 configured to perform one or more disclosed techniques when generating high frequency ground waves for pulses, according to one or more examples. For example, system 900 includes controller 902 and transmitter 904. System 900 may be configured to transmit signals (e.g., pulses in pulse groups of transmit cycles) according to one or more examples.

Controller 902 may be configured to receive data, e.g., from a control center. The data may include data for transmission, e.g., in data message pulses (e.g., as described above with respect to 2 described).

Additionally or alternatively, controller 902 may be configured to receive timing data, e.g., from a timing standard. The timing data may include a time of day, a pulse per second signal, or a frequency reference.

Controller 902 may calculate characteristics (e.g., timing, phase, or pulse shape) of signals (e.g., pulses in pulse groups of transmit cycles) to be transmitted. Controller 902 may calculate the characteristics such that the signals are in (aggregated) agreement according to one or more examples. Controller 902 may provide instructions to transmitter 904 that may indicate signals to be transmitted at transmitter 904.

As a non-limiting example, in various examples, controller 902 may provide transmitter 904 with an indication of a phase of a pulse to be transmitted. Additionally or alternatively, controller 902 may provide transmitter 904 with an indication of when to transmit a pulse (e.g., a pulse trigger).

Transmitter 904 may transmit signals, e.g., pulses in pulse groups of transmission cycles. Transmitter 904 may transmit pulses according to instructions from controller 902. Additionally or alternatively, transmitter 904 may transmit a pulse having a phase according to the indication of the phase provided by controller 902. Additionally or alternatively, transmitter 904 may transmit pulses at times indicated by controller 902, e.g., based on receiving a pulse trigger from controller 902.

As a non-limiting example, controller 902 may determine an interpulse interval such that system 900 has a unique (or unique within a geographic area) interpulse interval for identifying transmitter 904, e.g., as described above with respect to 1B Controller 902 may provide instructions (e.g., pulse triggers) so that transmitter 904 may emit pulses of a pulse group that certain interpulse interval.

As another non-limiting example, controller 902 may determine an arrangement of different types of pulses in pulse groups of transmit cycles, e.g., according to a pulse ordering scheme, e.g., as described above with respect to 2 Controller 902 may provide instructions so that transmitter 904 transmits pulses arranged in pulse groups of transmission cycles according to the determined arrangement.

As another non-limiting example, controller 902 may calculate dither, e.g., according to a dithering schedule, e.g., as described above with respect to 3 - 7 Controller 902 may provide instructions (e.g., pulse triggers) so that transmitter 904 transmits groups of pulses that are pre-sequenced or delayed (e.g., smeared) according to the calculated dither.

As another non-limiting example, controller 902 may determine a phase encoding for phases of pulses of pulse groups of transmit cycles, e.g., according to a pulse phase signature plan, e.g., as described above with respect to 8A-8C Controller 902 may provide phase instructions so that transmitter 904 transmits pulses having phases according to the determined phase encoding.

10 is a functional block diagram illustrating an example of a system 1000 configured to perform one or more disclosed techniques when generating high frequency ground waves for pulses, according to one or more examples. For example, system 1000 includes controller 1002, transmitter 1004, controller 1006, and transmitter 1008. System 1000 may be configured to transmit signals (e.g., pulses in pulse groups of transmit cycles) according to one or more examples. In particular, controller 1002 may provide instructions to transmitter 1004 to transmit signals, and controller 1006 may provide instructions to controller 1006 to transmit signals.

Each of controller 1002 and controller 1006 may be the same or substantially similar and/or perform the same operations as controller 902 of 9 Each of the transmitter 1004 and the transmitter 1008 may be the same or substantially similar and/or perform the same operations as transmitter 904 of 4 carry out.

In some examples, controller 1002 and transmitter 1004 may be at a first location and controller 1006 and transmitter 1008 may be at a second location remote from the first location. Controller 1002 and transmitter 1004 may be a first transmitter (e.g., TX1, which is related to 1A Controller 1006 and transmitter 1008 may be a second transmitter (e.g. TX2 referenced with respect to 1A referenced) that can generate second signals (e.g. PG1 from Tx2 104 and PG2 from Tx1 108).

In some examples, controller 1002 and transmitter 1004 may be from the same chain as controller 1006 and transmitter 1008. For example, controller 1002 and transmitter 1004 may generate pulses according to the first emission delay 402 of 4 and controller 1006 and transmitter 1008 may generate pulses that are offset according to second emission delay 404.

11 is a flow diagram of an example method 1100 according to various examples of the disclosure. At least a portion of method 1100 may, in some examples, be performed by an apparatus or system such as system 900 of 9 , Control 902 from 9 , channel 904 from 9 , System 1000 from 10 , Control 1002 of 10 , channel 1004 from 10 , Control 1006 of 10 , channel 1008 from 10 , or other device or system. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation.

At block 1102, an instruction to generate a signal including a location signal and a data signal may be received. For example, transmitter 904 may receive instructions from controller 902.

At block 1104, a signal may be transmitted. The signal may be transmitted via a terrestrial transmitter for transmitting radio waves comprising encoded message information and timing information for one or more of positioning, navigation, and timing. The signal may be at least partially responsive to the instruction. The signal may include a pulse group including a number of ranging pulses and a number of data pulses. Corresponding ones of the number of data pulses may have a phase of either a positive going phase or a negative going phase. The phases of respective ones of the number of data pulses of the pulse group may encode data. For example, the signal may be transmitted by transmitter 904.

12A and 12B collectively include a flowchart of an example method 1200 according to various examples of the disclosure. At least a portion of method 1200 may, in some examples, be performed by an apparatus or system such as system 900 of 9 , Control 902 from 9 , channel 904 from 9 , System 1000 from 10 , Control 1002 of 10 , channel 1004 from 10 , Control 1006 of 10 , channel 1008 from 10 , or other device or system. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation.

Block 1202 may be the same as Block 1102 of 11 Block 1204 may be the same as block 1104 of 11 be.

According to block 1206, which is optional, the data may include a message.

According to block 1208, which is optional, the data may include time information.

According to block 1210, which is optional, the data may include both message and time information.

According to block 1212, which is optional, the message (e.g., the message of block 1206) may be encrypted before encoding in the number of data pulses.

According to block 1214, which is optional, the message (e.g., the message of block 1206) may include additional timing information.

According to block 1216, which is optional, the pulse group may include a pulse length delay between the ranging pulses and the data pulses.

According to block 1218, which is optional, the data pulses may include a number of data message pulse sets, and each data message pulse set may encode data bits and an error correction bit.

According to block 1220, which is optional, the pulse group includes a pulse length delay between each of the data message pulse sets.

According to block 1222, which is optional, one or more of the data pulse groups encode at least a portion of a message, and one or more of the data pulse groups encode at least a portion of timing information.

13 is a flow diagram of an example method 1300 according to various examples of the disclosure. At least a portion of method 1300 may, in some examples, be performed by an apparatus or system such as system 900 of 9 , Control 902 from 9 , channel 904 from 9 , System 1000 from 10 , Control 1002 of 10 , channel 1004 from 10 , Control 1006 of 10 , channel 1008 from 10 , or other device or system. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation.

Block 1302 may be the same as Block 1102 of 11 For example, transmitter 1004 may receive instructions from controller 1002. Block 1304 may be the same as block 1104 of 11 be.

According to block 1306, which is optional, respective ones of the number of ranging pulses may have a phase of either a positive-going phase or a negative-going phase. Further, the phases of the respective ones of the number of ranging pulses of the pulse group may correspond to a pulse phase signature. Further, the pulse phase signature may be predefined for a transmission cycle and a terrestrial transmitter.

According to block 1308, which is optional, the pulse phase signature includes an indication of the phase of each of the number of pulses

According to block 1310, which is optional, the pulse phase signature may correspond to a predefined pulse phase signature schedule that includes a pulse phase signature for a number of transmit cycles.

14 is a flow diagram of an example method 1400 according to various examples of the disclosure. At least a portion of method 1400 may, in some examples, be performed by an apparatus or system such as system 900 of 9 , Control 902 from 9 , channel 904 from 9 , System 1000 from 10 , Control 1002 of 10 , channel 1004 from 10 , Control 1006 of 10 , channel 1008 from 10 , or other device or system. Although illustrated as discrete blocks, various blocks may be broken down into additional Blocks can be divided, combined into fewer blocks, or eliminated.

Block 1402 may be the same as Block 1102 of 11 Block 1404 may be the same as block 1104 of 11 be.

At block 1406, which is optional, another instruction to generate another signal may be received. For example, transmitter 1008 may receive instructions from controller 1006.

At block 1408, which is optional, a further signal may be transmitted. The further signal may be transmitted via a further terrestrial transmitter for transmitting radio waves comprising encoded message information and timing information for one or more of positioning, navigation, and timing. The further signal may be responsive, at least in part, to the further instruction. The further signal may include a pulse group including further ranging pulses separated by a further interpulse interval. For example, transmitter 1008 may transmit the further signal.

According to block 1410, which is optional, a length of the further interpulse interval indicates the further terrestrial transmitter.

15 is a flow diagram of an example method 1500 according to various examples of the disclosure. At least a portion of method 1500 may, in some examples, be performed by an apparatus or system such as system 900 of 9 , Control 902 from 9 , channel 904 from 9 , System 1000 from 10 , Control 1002 of 10 , channel 1004 from 10 , Control 1006 of 10 , channel 1008 from 10 , or other device or system. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation.

Block 1502 may be the same as Block 1102 of 11 Block 1504 may be the same as block 1104 of 11 be.

At block 1506, which is optional, another instruction to generate another signal may be received. For example, transmitter 1008 may receive instructions from controller 1006.

At block 1508, which is optional, a further signal may be transmitted. The further signal may be transmitted via a further terrestrial transmitter. The further signal may be at least partially responsive to the received further instruction. The further signal may include further pulse groups, the further pulse groups having an offset start time according to a further dithering interval. For example, transmitter 1008 may transmit the further signal.

According to block 1510, which is optional, the dithering interval and the further dithering interval may be transmitter-level dithering.

According to block 1512, which is optional, the dithering interval and the further dithering interval may be chain-level dithering.

According to block 1514, which is optional, the dithering interval and the further dithering interval may be masked dithering.

Modifications, additions, or omissions may be made to any of method 1100, method 1200, method 1300, method 1400, and method 1500 without departing from the scope of the present disclosure. For example, the acts of method 1100, method 1200, method 1300, method 1400, and/or method 1500 may be implemented in different orders. Furthermore, the listed acts and actions are provided as examples only, and some of the acts and actions may be optional, combined into fewer acts and actions, or expanded into additional ones.

16 is a functional block diagram illustrating a receiver 1602 according to one or more examples. Receiver 1602 includes an antenna 1604 and a processor 1606. Receiver 1602 may include a memory 1608. Memory 1608 is optional in receiver 1602. The optionality of memory 1608 is illustrated by memory 1608 illustrated with dashed lines. Receiver 1602 may determine PNT information from receiver 1602 based on received signals (e.g., signals transmitted according to any of the examples described herein). Additionally or alternatively, receiver 1602 may decode data encoded in the received signals.

As an example, processor 1606 of receiver 1602 may determine timing information based on one or more pulses of a received signal. For example, receiver 1602 may use a zero crossing of a pulse as an indication of a timing event, e.g., for positioning, navigation, and/or timing for a positioning technique (including, as non-limiting examples, multilateral or hyperbolic position estimation calculations). Processor 1606 may determine the position information based on a subset of received pulses, e.g., processor 1606 may determine the timing information based on ranging pulses, e.g., as in accordance with a pulse ordering scheme 200 of 2 identified.

Processor 1606 may decode one or more symbols of one or more pulses. For example, processor 1606 may decode the phase of one or more pulses (e.g., data pulses and/or timing pulses) into data symbols. For example, processor 1606 may observe phases of one or more pulses of a pulse group (e.g., the data pulses and/or the timing pulses, without limitation). Processor 1606 may compare the observed phases of the one or more pulses to entries in a table (stored in memory 1608 and/or securely accessible to receiver 1602, e.g., via a secured link). The table may correlate phases with data symbols.

As a non-limiting example, antenna 1604 may receive a signal encoding timing information for one or more of positioning, navigation, and timing. The signal may include a pulse group comprising a number of ranging pulses and a number of data pulses following the number of ranging pulses. Corresponding ones of the number of data pulses may have a phase of either a positive-going phase or a negative-going phase. Data may be encoded using either the positive-going phases or the negative-going phases of the data signals. Processor 1606 may decode the data at least partially in response to the phases of the respective ones of the number of data pulses.

As a non-limiting example, antenna 1604 may receive a signal encoding timing information for one or more of positioning, navigation, and timing. The signal may include a pulse group comprising a number of ranging pulses and a number of data pulses. Corresponding ones of the number of data pulses may have a phase of either a positive going phase or a negative going phase. Processor 1606 may observe phases of the respective ones of the number of data pulses. Processor 1606 may obtain data at least in part in response to the phases of the respective ones of the number of data pulses.

Processor 1606 may identify and/or validate a transmitter of the received signal based on the received signal. For example, processor 1606 may determine one or more interpulse intervals (e.g., nominal interpulse intervals) (e.g., interpulse interval 128 of 1B) of the signal and compare the measured one or more interpulse intervals to a list relating interpulse interval values to transmitter identifiers, the list stored in memory 1608 at receiver 1602 and/or securely accessible to receiver 1602, e.g., retrieved from receiver 1602 via a secure link. Processor 1606 may identify or verify a transmitter transmitting the signal based on a match between an interpulse interval value of the signal and an interpulse interval value in the list.

As a non-limiting example, antenna 1604 may receive a location signal encoding timing information for one or more of positioning, navigation, and timing. The ranging signal may include a first pulse of a pulse group, a second pulse of the pulse group, and an interpulse interval between a start of the first pulse and a start of the second pulse. Processor 1606 may identify a transmitter of the ranging signal at least in part in response to the interpulse interval. Memory 1608 may store a correlation between the interpulse interval and the transmitter. Processor 1606 may identify the transmitter in response to the correlation.

Additionally or alternatively, receiver 1602 may, without limitation, have a pulse location scheme definition (e.g., stored in memory 1608 of receiver 1602), e.g., according to pulse ordering scheme 200 of 2 . Additionally or alternatively, the pulse location scheme definition may be securely accessible to receiver 1602, e.g., retrieved by receiver 1602 via a secure link. Using the pulse location scheme, receiver 1602 may determine which pulses of a pulse group are ranging pulses, which are time message pulses, and which are data message pulses according to the pulse ordering scheme.

Receiver 1602 may have an encryption key (e.g., stored in memory 1608, without limitation) and may use the encryption key to decrypt that has been encrypted in data pulses and/or timing pulses. Decrypting timing information in timing pulses may provide receiver 1602 with access to additional timing information that receiver 1602 may use to increase the accuracy of certain position information. Additionally or alternatively, the encryption key may be securely accessible to receiver 1602, e.g., retrieved by receiver 1602 via a secure link.

As a non-limiting example, antenna 1604 may receive a location signal encoding message information and timing information for one or more of positioning, navigation, and timing. The ranging signal may include a pulse group comprising a number of pulses, where first pulses of the number of pulses encode a first data type and second pulses of the number of pulses encode a second data type. Processor 1606 may identify the first pulses and the second pulses at least in part in response to an order of the first pulses and the second pulses in the pulse group and a prespecified pulse ordering scheme. Memory 1608 may store the prespecified pulse ordering scheme.

Receiver 1602 may have a dithering schedule (e.g., stored in memory 1608, without limitation). Additionally or alternatively, the dithering schedule may be securely accessible to receiver 1602, e.g., retrieved by receiver 1602 via a secure link. Using the dithering schedule, receiver 1602 may correct for the effects of dithering on the received signals. By correcting for the effects of dithering, receiver 1602 may increase the accuracy of the calculated positioning, navigation, or timing information. Receiver 1602 may correct for the effects of chain-level dithering, transmitter-level dithering, and/or masked dithering, e.g., chain-level dithering, transmitter-level dithering, and/or masked dithering as described with respect to 3 to 7 described, correct.

As a non-limiting example, antenna 1604 may receive a positioning signal encoding timing information for one or more of positioning, navigation, and timing. The ranging signal may include a burst, where the burst is delayed from a nominal burst start time by a dithering interval. Processor 1606 may calculate a transmission time of the burst. Processor 1606 may adjust the calculated transmission time to account for the dithering interval. Memory 1608 may store a dithering schedule, and processor 1606 may determine the dithering interval at least in part in response to the dithering schedule.

For example, receiver 1602 may identify or verify a transmitter of a signal based at least in part on a pulse phase signature of one or more pulses of a pulse group. For example, receiver 1602 may determine a phase of one or more pulses (e.g., ranging pulses) of a pulse group. Receiver 1602 may compare the determined phases of the pulses to a pulse phase signature map, where the pulse phase signature map may be stored in memory 1608 at receiver 1602 and/or securely accessible to receiver 1602, e.g., retrieved by receiver 1602 via a secure link. Receiver 1602 may identify a transmitter that transmitted the signal based on a match between the measured phases of the pulses and the pulse phase signature in the pulse phase signature map. In such examples, the signal may have been transmitted as described above with respect to FIGS. 8A-8C.

As a non-limiting example, antenna 1604 may receive a location signal encoding timing information for one or more of positioning, navigation, and timing. The ranging signal may include a pulse group including a number of ranging pulses and a number of data pulses, wherein each of the number of ranging pulses has either a positive going phase or a negative going phase. Processor 1606 may validate a transmitter of the ranging signal by comparing phases of the number of ranging pulses to a pulse phase signature of the transmitter. Memory 1608 may store the pulse phase signature.

17 is a functional block diagram illustrating a system including a transmitter 1716 and a receiver 1708, according to one or more examples. Transmitter 1716 may be an example of one of the transmitters 904 of 9 , the station 1004 from 10 and the transmitter 1008 from 10 Receiver 1708 may be an example of receiver 1602 of 16 be.

As a non-limiting example, a signal 1702 may be a location signal to be transmitted at a transmitter antenna 1704 of a transmitter 1716. A signal 1706 may be the ranging signal transmitted as a radio frequency transmission at the transmitter antenna 1704. Signal 1706 may be transmitted at an antenna 1710 a receiver 1708. Receiver 1708 may generate data 1714 based on signal 1706 using a processor 1712. Data 1714 may include position, navigation, and/or timing information. Data 1714 may further include a message.

18 is a functional block diagram illustrating one or more operations 1800 that may occur at a receiver according to one or more examples. Operations 1800 may be performed on receivers 1602 from 16 and/or recipient 1708 of 17 occur and/or are performed by the recipient. Operations 1800 may be part of a capture phase of operations of a recipient.

Signal 1802 may be a received signal including one or more blocks of data at one or more respective times. As a non-limiting example, signal 1802 may be a ranging signal including one or more pulses or groups of pulses from one or more epochs. Signal 1802 may be an example of signal 1706 from 17 as in receiver 1708 of 17 received.

At signal acquisition 1804, signal 1802 may be acquired using a matched filter. As a non-limiting example, received signals at one or more frequencies may be compared to predetermined patterns of one or more matched filters to acquire digital samples representative of signal 1802. At signal acquisition 1804, a start time of an epoch may be determined. Further, since a duration of an epoch may be known, a nominal start time of subsequent epochs may also be determined at signal acquisition 1804. The epoch start time may be provided to pulse formation 1808 and/or data decoding 1812 may be included either directly from signal acquisition 1804 or the epoch start time in information 1810 and/or information 1814.

Information 1806 provided to signal acquisition 1804 may be or include information used to acquire the signal at signal acquisition 1804. Information 1806 may include one or more signal replicas, e.g., replicas of a portion of signal 1802 minus unknown data (e.g., a message encoded by the signal and/or noise). The signal replicas may include replicas of one or more pulses and/or one or more groups of pulses. In some examples, the signal replicas may include pulses of an epoch. The signal replicas may be pre-computed for the receiver to correlate with signal 1802 to acquire signal 1802. The signal replicas may be based at least in part on an interpulse interval, where the interpulse interval may be unique with respect to a transmitter (e.g., as described with respect to 1B The interpulse interval may also be unique to the signal to be detected. Additionally or alternatively, the signal replica may be based at least in part on an unencrypted pulse phase signature (e.g. as described with respect to 8A , 8B and 8C described). The pulse phase signature can also be unique to the signal to be detected.

In pulse formation 1808, a mixed pulse may be formed. The mixed pulse may be based on an average of two or more pulses. For example, in some situations, it may be difficult or inaccurate to calculate an arrival time of a pulse based on a single pulse due to noise or other deviations. Thus, averaging multiple pulses to form a mixed pulse may enable a more accurate calculation of an arrival time of the mixed pulse. With respect to 1C and 1D For the pulses described above, averaging may include averaging a leading edge of a plurality of pulses. The averaging interval may be selected based on platform dynamics (e.g., motion of a platform of the receiver). The two or more pulses to be averaged may be selected to be pulses that are not subject to encoding delay. For example, according to a pulse ordering scheme (e.g., pulse ordering scheme 200 of 2 ) Distance measuring pulses that are not delayed by an encoding delay are selected to be averaged in pulse formation 1808.

In pulse formation 1808, the one or more pulses formed in pulse formation 1808 may be analyzed. As a non-limiting example, a pulse envelope (e.g., pulse envelope 144 of 1C ). Additionally or alternatively, phase tracking points (e.g., points in the pulse at which a phase of the pulse can be determined) may be identified. Additionally or alternatively, an arrival time of one of more of the pulses may be determined during pulse formation 1808. Information 1824 may include one or more pieces of information relating to one or more pulses, e.g., the pulses formed during pulse formation 1808. Information 1824 may include, for example, pulse start times (e.g., range-measuring pulse start times) and/or inter-pulse intervals (e.g., nominal interpulse intervals). Pulse formation 1808 may provide information 1824 for data decoding 1812.

Information 1810 may be or include information used to form the mixing pulses in pulse formation 1808. Information 1810 may include epoch start times. Epoch start times may be or include an index into a data vector. The data vector may be related to time.

At data decoding 1812, an epoch number 1816 and messages 1818 (including, for example, time messages and/or data messages) may be decoded from the signal 1802. As a non-limiting example, phases of pulses (e.g., as described with respect to 1C and 1D described) (e.g., ranging pulses) can be identified, phases of multiple pulses can be decoded into data. For example, the phases of a set of pulses can be translated into a data symbol by comparing the phases of the set of pulses to entries in a table that correlates pulse phases with data symbols.

Additionally or alternatively, according to a nominal interpulse interval, unique interpulse intervals (e.g. as in relation to 1B described) and/or a nominal group repetition interval, pulse groups and/or individual pulses within the acquired signal can be identified. As a non-limiting example, start and/or end times (e.g. as defined by 1C and or 1D illustrated) individual pulses can be identified. Based on the start and/or end times, the captured signal can be parsed into pulses.

According to a pulse ordering scheme (e.g. pulse ordering scheme 200 of 2 ), template pulses, data pulses and/or timing pulses can be identified from the received pulses. According to a pulse phase signature (e.g. as described in relation to 8A , 8B and 8C described), phases of each ranging pulse can be corrected (e.g., phase codes can be smeared from the pulses). The data pulses and/or timing pulses can be identified so that data (encoded as phases of the data and/or timing pulses) can be decoded.

The particular symbols or bits of data decoded at data decoding 1812 may be input without restriction to an error correction algorithm, such as a Reed Solomon Forward Correction (FEC) algorithm. If a number of errors are such that the error correction algorithm can correct the errors, the error correction algorithm may return the correct message as messages 1818. If the error correction algorithm rejects the time message during the acquisition phase, the receiver may not have successfully acquired the signal (e.g., at signal acquisition 1804). If the receiver did not successfully acquire the signal, subsequent data blocks of the signal may be acquired and the process may begin again.

One or more timing message pulses may be decoded into symbols and timing message bits. If the error correction algorithm determines that the message has no errors, or the error correction algorithm has corrected the errors, the timing message bits may be parsed into an epoch number 1816 to be passed to signal validation 1820 and/or other associated timing data.

In data decoding 1812, the epoch number 1816 may be combined with a cryptographic key 1822 (alternatively referred to herein as "key 1822") to decrypt the data message. The data message may be parsed into information such as, but not limited to, differential corrections and/or a data message.

Information 1814 may include information used in data decoding 1812 to decode data from the acquired signal. Information 1814 may include a cryptographic key (e.g., used to decode the data message in data decoding 1812). Additionally or alternatively, information 1814 may include the pulse ordering scheme. Additionally or alternatively, information 1814 may include the epoch start time.

At signal validation 1820, signal 1802 may be validated, e.g., based on a correspondence between phases of pulses of signal 1802 and a pulse phase signature. In some examples, signal validation 1820 may provide phase codes and/or epoch start time for pulse formation 1808.

As a non-limiting example, epoch number 1816 and key 1822 may be inputs to signal validation 1820. During signal validation 1820, an index of a lookup table of pulse phase signatures may be determined (e.g., based at least in part on epoch number 1816). As a non-limiting example, epoch number 1816 and key 1822 may be used as input to a cryptographic algorithm (not shown) that determines an index a lookup table of pulse phase signatures. The lookup table may return a pulse phase signature (in response to epoch number 1816 and key 1822). If the phases of signal 1802 match the pulse phase signature, signal 1802 may be validated.

In some examples, epoch number 1816, obtained (at data decoding 1812) by decoding a timing message during an epoch when the unencrypted pulse phase signature was transmitted, may be incremented and used to return the pulse phase signature of the next epoch of signal 1802. If this sequence was encrypted, the encrypted pulse phase signature is correlated with the received signal 1802. If the correlation is sufficiently positive (e.g., meets or exceeds a predetermined threshold, without limitation), signal 1802 is authenticated, the receiver has been successfully acquired, and proceeds to the tracking phase.

19 is a functional block diagram illustrating one or more operations 1900 that may occur at a receiver according to one or more examples. Operations 1900 may be performed on receivers 1602 from 16 and/or recipient 1708 of 17 and/or performed by a receiver. Operations 1900 may be part of a tracking phase of a receiver's operation. Operation 1900 may follow successful completion of one or more operations 1800.

Signal 1902 can be the same as signal 1802 from 18 Signal validation 1920 may be the same as or substantially similar to signal validation 1820 of 18 Key 1904 may be equal or substantially similar to key 1822 of 18 and epoch number 1906 may be equal to or substantially similar to epoch number 1816 of 18 be.

In addition to the operations described with respect to signal validation 1820, signal validation 1920 may provide phase codes to pulse formation 1908 and/or data decoding 1912. As a non-limiting example, at signal validation 1920, signal validation 1920 may validate signal 1902 at least in part in response to a match between phases of signal 1902 and a pulse phase signature of a table of valid pulse phase signatures. Additionally or alternatively, the pulse phase signature may be used at data decoding 1912 to blur the phase code prior to the demodulation process. Additionally or alternatively, the pulse phase signature may also be used at pulse formation 1908 to blur the phase code prior to generating the mixed or averaged pulse.

Impulse formation 1908 can be the same as impulse formation 1808 of 18 or substantially similar to it. Information 1910 may be the same as information 1810 of 18 or substantially similar thereto. Data decoding 1912 may be the same as data decoding 1812 of 18 or substantially similar to it. Information 1914 may be the same as Information 1814 of 18 or substantially similar thereto. Epoch number 1906, key 1904, and/or an epoch start time may be included in information 1914. In addition to the operations described with respect to data decoding 1812, data decoding 1912 may generate differential corrections 1928. Differential corrections 1928 may be based at least in part on a decoded data message.

In time calculation 1916, a nominal transmission time (TOT) of an epoch (e.g., a current epoch) of signal 1902 may be calculated. The nominal TOT may be the epoch number multiplied by the epoch duration plus the nominal emission delay for the particular station.

Additionally or alternatively, dither may be corrected in timing calculation 1916. As a non-limiting example, dither may be taken into account and/or corrected in timing calculation 1916 when determining a TOT of signal 1902 for the relevant epoch. In timing calculation 1916, one or more dithering offsets may be determined, e.g., by indexing into a dithering schedule using epoch number 1906 (e.g., as described with respect to 3 to 7 The dithering offsets can be added to or subtracted from the TOT to obtain a TOT that is not distorted by dithering.

At time information calculation 1922, timing information may be calculated. As a non-limiting example, an offset between a local time and Coordinated Universal Time (UTC) may be determined. The timing information may be calculated based on signal 1902 (e.g., as analyzed at pulse formation 1908). As a non-limiting example, at time information calculation 1922, timing information may be calculated at least in part in response to an arrival time of one or more pulses of signal 1902, e.g., as identified at pulse formation 1908. In In some cases, the time of arrival of one or more pulses may be refined or updated in response to a particular offset between local time and UTC. Additionally or alternatively, the timing information at time information calculation 1922 may be calculated at least in part based on differential corrections 1928, where differential corrections 1928 were determined at data decoding 1912. As a non-limiting example, the timing information at data decoding 1912 may be decoded from time message pulses. The timing information may include differential corrections. At time information calculation 1922, the differential corrections may be applied. Additionally or alternatively, the transmission time, e.g., after the effects of dithering have been corrected (where corrections may have occurred at time calculation 1916), may be used to calculate the timing information at time information calculation 1922.

At PNT calculation 1924, PNT information 1926 may be calculated. PNT information 1926 may include a position of the receiver, e.g., relative to one or more transmitters. PNT information 1926 may include a latitude and longitude of the receiver. PNT information 1926 may be calculated at PNT calculation 1924 based at least in part on differences between transmission times of signals (including, e.g., signal 1902) from two or more transmitters (where transmission times may have been calculated at time calculation 1916) and arrival times of the signals (where arrival times were calculated at pulse formation 1908 and/or arrival times were adjusted or refined at time information calculation 1922). PNT information 1926 may be calculated in PNT calculation 1924 using a positioning technique (including, as non-limiting examples, multilateral position estimation or hyperbolic position estimation calculations).

Additionally or alternatively, the receiver may be used in PNT calculation 1924 for monitoring, surveying, or timing purposes. For example, the receiver may compare the received arrival time to a predicted received time according to a standard model. The difference between the received time and the predicted received time may be used for signal monitoring, surveying, and/or calculating differential correction information.

20 is a flowchart illustrating a method 2000 for receiving radio waves and decoding data encoded by the radio waves, according to one or more examples. In particular, method 2000 may be for receiving radio waves by a terrestrial transmitter, the radio waves encoding message information and timing information for one or more of positioning, navigation, and timing, and for decoding data encoded by a signal of the radio waves. Method 2000 may be performed by a receiver, such as receiver 1602 of 16 or recipient 1708 of 17 .

At operation 2002, a signal may be received that encodes timing information for one or more of positioning, navigation, and timing. The signal may include a pulse group comprising a number of ranging pulses and a number of data pulses after the number of ranging pulses. Pulses corresponding to the number of data pulses may have a phase of either a positive going phase or a negative going phase. Data may be encoded using either the positive going phases or the negative going phases of the data signals. The signal received at operation 1102 of 11 transmitted signal can be an example of the signal received at 2002.

In operation 2004, the data may be decoded at least in part in response to the phases of each of the plurality of data pulses.

In operation 2006, which is optional, the data (or part of the data) can be decrypted.

In operation 2008, which is optional, a message can be derived from the data.

In process 2010, which is optional, the message can be made available for presentation, for example on a screen.

In operation 2012, which is optional, timing information of the processor (or used by the processor) may be updated at least in part in response to the data. For example, the data may include timing information. The processor may use the timing information to update timing information of the processor or the recipient.

In operation 2014, which is optional, a location (e.g., of the recipient) may be determined at least in part in response to the updated timing information. For example, an arrival time is calculated based at least in part on the updated timing information as updated in response to the timing information encoded in the signal.

In operation 2016, which is optional, a location (e.g., of the receiver) may be determined at least in part in response to the number of ranging pulses of the signal.

21 is a flowchart illustrating a method 2100 for receiving radio waves and decoding data encoded by the radio waves, according to one or more examples. In particular, method 2100 may be for receiving radio waves by a terrestrial transmitter, the radio waves encoding message information and timing information for one or more of positioning, navigation, and timing, and for decoding data encoded by a signal of the radio waves.

Method 2100 may be performed by a receiver, such as receiver 1602 of 16 or recipient 1708 of 17 .

At operation 2102, a signal may be received that encodes timing information for one or more of positioning, navigation, and timing. The signal may include a pulse group comprising a number of ranging pulses and a number of data pulses. Corresponding to the number of data pulses may have a phase of either a positive going phase or a negative going phase. The signal received at operation 1102 of 11 transmitted signal may be an example of the signal received at 2102.

At operation 2104, phases of each of the number of data pulses may be observed. The observations regarding phases may be recorded.

In operation 2106, data may be obtained at least in part in response to the phases of each of the number of data pulses.

In operation 2108, which is optional, the phases of each of the number of data pulses may be compared to entries in a table that correlates data symbols with sets of phases of pulses.

In operation 2110, which is optional, a location (e.g., of the receiver) may be determined at least in part in response to the number of ranging pulses.

Modifications, additions or omissions may be made to any of Procedure 2000 of 20 and/or Procedure 2100 of 21A without departing from the scope of the present disclosure. For example, the acts of each of the method 2000 of 20 and/or the procedure 2100 of 21 be implemented in different orders. Furthermore, the operations and actions outlined are provided as examples only, and some of the operations and actions may be optional, combined into fewer operations and actions, or expanded into additional operations and actions without affecting the essence of the disclosed example.

As used in the present disclosure, the term "combination" in reference to a plurality of elements may include a combination of all of the elements or any of several different subcombinations of some of the elements. For example, the phrase "A, B, C, D, or combinations thereof" may refer to any of A, B, C, or D; the combination of any of A, B, C, and D; and any subcombination of A, B, C, or D, such as A, B, and C; A, B, and D; A, C, and D; B, C, and D; A and B; A and C; A and D; B and C; B and D; or C and D.

Terms used in the present disclosure and particularly in the appended claims (e.g., contents of the appended claims) are generally intended to be "open-ended" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "comprising" should be interpreted as "at least comprising," the term "includes" should be interpreted as "includes but is not limited to," but not limited to"). As used herein, "each" means some or a whole. As used herein, "all" means a whole.

In addition, if a specific number of introduced claim statements are intended, that intention will be expressly stated in the claim, and in the absence of such a statement, no such intention exists. For example, as an aid to understanding, the following accompanying claims may include the use of the introductory phrases “at least one” and “one or more” to introduce claim statements. However, the use of such phrases should not be construed to imply that the introduction of a claim statement by the indefinite articles “a” or “an” limits a particular claim containing such introduced claim statement to examples containing only one such statement, even if the same Claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" and/or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same applies to the use of definite articles used to introduce claim particulars.

Moreover, even if a particular number of introduced claim specifications is explicitly stated, those skilled in the art will recognize that such a specification should be interpreted to mean at least the stated number (e.g., merely stating “two specifications” without other modifiers means at least two specifications or two or more specifications). Furthermore, where a convention analogous to “at least one of, but not limited to, A, B, and C” or “one or more of, but not limited to, A, B, and C” is used, such a construction is generally intended to include A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together, but not limited to

Furthermore, any disjunctive word or phrase representing two or more alternative terms, whether in the description, claims or drawings, should be understood to contemplate the possibility of including either term, one term or the other, or both terms. For example, the phrase "A or B" should be understood to include the possibilities "A" or "B" or "A and B".

• Beispiel 1: Verfahren, umfassend: Empfangen einer Anweisung zum Erzeugen eines Signals, das ein Entfernungsmesssignal und ein Datensignal umfasst; und Übertragen, über einen terrestrischen Sender zum Übertragen von Funkwellen mit codierten Nachrichteninformationen und Zeitinformationen für eine oder mehrere von Positionierung, Navigation und Zeitsteuerung, wobei das Signal zumindest teilweise auf die Anweisung reagiert, wobei das Signal eine Impulsgruppe umfasst, die eine Anzahl von Entfernungsmessimpulsen und eine Anzahl von Datenimpulsen nach der Anzahl von Entfernungsmessimpulsen umfasst, wobei jeweilige der Anzahl von Datenimpulsen eine Phase von entweder einer positiv verlaufenden Phase oder einer negativ verlaufenden Phase aufweist, wobei Daten unter Verwendung der entweder positiv verlaufenden Phasen oder der negativ verlaufenden Phasen der Datenimpulse codiert werden.
• Beispiel 2: Verfahren nach Beispiel 1, wobei die Daten eine Nachricht umfassen.
• Beispiel 3: Verfahren nach einem der Beispiele 1 bis 2, wobei die Daten Zeitinformationen umfassen.
• Beispiel 4: Verfahren nach einem der Beispiele 1 bis 3, wobei die Daten eine Nachricht und Zeitinformationen umfassen.
• Beispiel 5: Verfahren nach einem der Beispiele 1 bis 4, wobei die Nachricht vor dem Codieren in der Anzahl von Datenimpulsen verschlüsselt wird.
• Beispiel 6: Verfahren nach einem der Beispiele 1 bis 5, wobei die Nachricht zusätzliche Zeitsteuerungsinformationen einschließt.
• Beispiel 7: Verfahren nach einem der Beispiele 1 bis 6, wobei die Impulsgruppe eine Impulslängenverzögerung zwischen der Anzahl von Entfernungsmessimpulsen und der Anzahl von Datenimpulsen umfasst.
• Beispiel 8: Verfahren nach einem der Beispiele 1 bis 7, wobei die Anzahl von Datenseimpulsen eine Anzahl von Datennachrichtenimpulssätzen umfasst und jeder Datennachrichtenimpulssatz Datenbits und ein Fehlerkorrekturbit codiert.
• Beispiel 9: Verfahren nach einem der Beispiele 1 bis 8, wobei die Impulsgruppe eine Impulslängenverzögerung zwischen jeder der Anzahl von Datennachrichtenimpulssätzen umfasst.
• Beispiel 10: Verfahren nach einem der Beispiele 1 bis 9, wobei einer oder mehrere der Datennachrichtenimpulssätze mindestens einen Abschnitt einer Nachricht codiert und einer oder mehrere der Datennachrichtenimpulssätze mindestens einen Abschnitt von Zeitinformationen codiert.
• Beispiel 11: Verfahren nach einem der Beispiele 1 bis 10, wobei jeweilige der Anzahl von Entfernungsmessimpulsen eine Phase von entweder einer positiv verlaufenden Phase oder einer negativ verlaufenden Phase aufweisen, wobei die Phasen der jeweiligen der Anzahl von Entfernungsmessimpulsen der jeweiligen Impulsgruppe einer Impulsphasensignatur entsprechen und die Impulsphasensignatur für einen Sendezyklus und einen terrestrischen Sender vordefiniert sind.
• Beispiel 12: Verfahren nach einem der Beispiel 1 bis 11, wobei die Impulsphasensignatur eine Angabe der Phase jeder der Anzahl von Entfernungsmessimpulsen umfasst.
• Beispiel 13: Verfahren nach einem der Beispiele 1 und 12, wobei die Impulsphasensignatur einem vordefinierten Impulsphasensignaturplan entspricht, umfassend eine Impulsphasensignatur für eine Anzahl von Sendezyklen.
• Beispiel 14: Verfahren nach einem der Beispiele 1 bis 13, wobei jeder der Anzahl von Entfernungsmessimpulsen durch ein Zwischenimpulsintervall getrennt ist, eine Länge des Zwischenimpulsintervalls den terrestrischen Sender angibt.
• Beispiel 15: Verfahren nach einem der Beispiele 1 bis 14, umfassend: Empfangen einer weiteren Anweisung zum Erzeugen eines weiteren Signals; und Übertragen, über einen weiteren terrestrischen Sender zum Übertragen von Funkwellen mit codierten Nachrichteninformationen und Zeitinformationen für eines oder mehrere von Positionierung, Navigation und Zeitsteuerung, wobei das weitere Signals zumindest teilweise auf die weitere Anweisung reagiert, wobei das weitere Signal eine Impulsgruppe umfasst, die weitere Entfernungsimpulse umfasst, die durch ein weiteres Zwischenimpulsintervall getrennt sind.
• Beispiel 16: Verfahren nach einem der Beispiele 1 bis 15, wobei eine Länge des weiteren Zwischenimpulsintervalls den weiteren terrestrischen Sender angibt.
• Beispiel 17: Verfahren nach einem der Beispiele 1 bis 16, wobei das Übertragen des Signals das Versetzen einer Startzeit der Impulsgruppe durch ein Dithering-Intervall umfasst.
• Beispiel 18: Verfahren nach einem der Beispiele 1 bis 17, umfassend: Empfangen einer weiteren Anweisung zum Erzeugen eines weiteren Signals; und Übertragen, über einen weiteren terrestrischen Sender, des weiteren Signals als Reaktion auf die empfangene weitere Anweisung, wobei das weitere Signal weitere Impulsgruppen aufweist, wobei die weiteren Impulsgruppen Versatzstartzeiten gemäß einem weiteren Dithering-Intervall aufweisen.
• Beispiel 19: Verfahren nach einem der Beispiele 1 bis 18, wobei das Dithering-Intervall und das weitere Dithering-Intervall Dithering auf Senderebene sind.
• Beispiel 20: Verfahren nach einem der Beispiele 1 bis 19, wobei das Dithering-Intervall und das weitere Dithering-Intervall Dithering auf Kettenebene sind.
• Beispiel 21: Verfahren nach einem der Beispiele 1 bis 20, wobei das Dithering-Intervall und das weitere Dithering-Intervall maskiertes Dithering und eine Dithering-Intervall gemäß einer Rampe umfassen.
• Beispiel 22: Einrichtung, umfassend: eine Steuerung zum: Erzeugen einer Anweisung zum Erzeugen eines Signals, das ein Entfernungsmesssignal und ein Datensignal umfasst, wobei das Signal eine Impulsgruppe umfasst, die eine Anzahl von Entfernungsmessimpulsen und eine Anzahl von Datenimpulsen nach der Anzahl von Entfernungsmessimpulsen umfasst, wobei jeweilige der Anzahl von Datenimpulsen eine Phase entweder einer positiv verlaufenden Phase oder einer negativ verlaufenden Phase aufweisen, wobei Informationen unter Verwendung der entweder positiv verlaufenden Phasen oder der negativ verlaufenden Phasen der Datensignale codiert werden; und Bereitstellen der Anweisung an einen terrestrischen Sender zum Übertragen von Funkwellen, die codierte Nachrichteninformationen und Zeitsteuerungsinformationen für eines oder mehrere von Positionierung, Navigation und Zeitsteuerung aufweisen;
• Beispiel 23: Vorrichtung, umfassend: eine Antenne, um ein Signal zu empfangen, das Zeitsteuerungsinformationen für eines oder mehrere von Positionierung, Navigation und Zeitsteuerung codiert, wobei das Signal eine Impulsgruppe umfasst, die eine Anzahl von Entfernungsmessimpulsen und eine Anzahl von Datenimpulsen nach der Anzahl von Entfernungsmessimpulsen umfasst, wobei jeweilige der Anzahl von Datenimpulsen eine Phase entweder einer positiv verlaufenden Phase oder einer negativ verlaufenden Phase aufweisen, wobei Daten unter Verwendung der entweder positiv verlaufenden Phasen oder der negativ verlaufenden Phasen der Datensignale codiert werden; und einen Prozessor, um die Daten zumindest teilweise als Reaktion auf die Phasen der jeweiligen der Anzahl von Datenimpulsen zu decodieren.
• Beispiel 24: Vorrichtung nach Beispiel 23, wobei der Prozessor die Daten entschlüsseln soll.
• Beispiel 25: Vorrichtung nach einem der Beispiele 23 und 24, wobei der Prozessor eine Nachricht aus den Daten ableiten soll.
• Beispiel 26: Vorrichtung nach einem der Beispiele 23 bis 25, wobei der Prozessor die Nachricht zur Präsentation bereitstellen soll.
• Beispiel 27: Vorrichtung nach einem der Beispiele 23 bis 26, wobei der Prozessor die Zeitsteuerungsinformationen des Prozessors zumindest teilweise als Reaktion auf die Daten aktualisieren soll.
• Beispiel 28: Vorrichtung nach einem der Beispiele 23 bis 27, wobei der Empfänger dazu dient, einen Standort der Vorrichtung zumindest teilweise als Reaktion auf die aktualisierten Zeitsteuerungsinformationen zu bestimmen.
• Beispiel 29: Vorrichtung nach einem der Beispiele 23 bis 28, wobei der Prozessor dazu dient, eine Nachricht aus den Daten abzuleiten und Zeitsteuerungsinformationen des Prozessors zumindest teilweise als Reaktion auf die Daten zu aktualisieren.
• Beispiel 30: Vorrichtung nach einem der Beispiele 23 bis 29, wobei der Prozessor einen Abschnitt der Daten, aus denen die Nachricht abgeleitet wird, entschlüsseln soll.
• Beispiel 31: Vorrichtung nach einem der Beispiele 23 bis 30, wobei jeweilige der Anzahl von Entfernungsmessimpulsen eine Phase entweder einer positiv verlaufenden Phase oder einer negativ verlaufenden Phase aufweisen, wobei die Phasen der jeweiligen der Anzahl von Entfernungsmessimpulsen der Impulsgruppe einer Impulsphasensignatur entsprechen, und wobei der Prozessor dazu dient, einen Sender eines Entfernungsmesssignals durch Vergleichen von Phasen der Anzahl von Entfernungsmessimpulsen mit der Impulsphasensignatur des Senders zu validieren.
• Beispiel 32: Vorrichtung nach einem der Beispiele 23 bis 31, wobei der Prozessor dazu dient, einen Sender eines Entfernungsmesssignals zumindest teilweise als Reaktion auf ein Zwischenimpulsintervall zu identifizieren, wobei das Zwischenimpulsintervall eine Dauer einer Zeittrennung zwischen der Anzahl von Entfernungsmessimpulsen ist.
• Beispiel 33: Vorrichtung nach einem der Beispiele 23 bis 32, wobei der Prozessor zu Folgendem dient: Erhalten einer Übertragungszeit der Impulsgruppe; und Anpassen der berechneten Übertragungszeit, um ein Dithering-Intervall zu berücksichtigen.
• Beispiel 34: Vorrichtung nach einem der Beispiele 23 bis 33, wobei der Empfänger dazu dient, einen Standort zumindest teilweise als Reaktion auf die angepasste Übertragungszeit zu bestimmen.
• Beispiel 35: Vorrichtung nach einem der Beispiele 23 bis 34, wobei der Prozessor dazu dient, einen Standort zumindest teilweise als Reaktion auf die Anzahl von Entfernungsmessimpulsen zu bestimmen.
• Beispiel 36: Vorrichtung, umfassend: eine Antenne, um ein Signal zu empfangen, das Zeitsteuerungsinformationen für eines oder mehrere von Positionierung, Navigation und Zeitsteuerung codiert, wobei das Signal eine Impulsgruppe umfasst, die eine Anzahl von Entfernungsmessimpulsen und eine Anzahl von Datenimpulsen umfasst, wobei jeweilige der Anzahl von Datenimpulsen eine Phase von entweder einer positiv verlaufenden Phase oder einer negativ verlaufenden Phase aufweisen; und einen Prozessor zum: Beobachten von Phasen der jeweiligen der Anzahl von Datenimpulsen; und Erhalten von Daten zumindest teilweise als Reaktion auf die Phasen der jeweiligen der Anzahl von Datenimpulsen.
• Beispiel 37: Vorrichtung nach Beispiel 36, wobei die Vorrichtung einen Speicher zum Speichern einer Tabelle umfasst, die Datensymbole mit Sätzen von Phasen von Impulsen korreliert; und wobei der Prozessor dazu dient, die Phasen der jeweiligen der Anzahl von Datenimpulsen mit Einträgen in der Tabelle zu vergleichen, um die Daten zu erhalten.
• Beispiel 38: Vorrichtung nach einem der Beispiele 36 bis 37, wobei der Prozessor dazu dient, einen Standort der Vorrichtung zumindest teilweise als Reaktion auf die Anzahl von Entfernungsmessimpulsen zu bestimmen.
• Beispiel 39: Verfahren, umfassend: Empfangen eines Signals, das Zeitsteuerungsinformationen für eines oder mehrere von Positionierung, Navigation und Zeitsteuerung codiert, wobei das Signal eine Impulsgruppe umfasst, die eine Anzahl von Entfernungsmessimpulsen und eine Anzahl von Datenimpulsen umfasst, wobei jeweilige der Anzahl von Datenimpulsen eine Phase von entweder einer positiv verlaufenden Phase oder einer negativ verlaufenden Phase aufweisen; Beobachten von Phasen der jeweiligen der Anzahl von Datenimpulsen; und Erhalten von Daten zumindest teilweise als Reaktion auf die Phasen der jeweiligen der Anzahl von Datenimpulsen.
• Beispiel 40: Verfahren nach Beispiel 39, umfassend das Vergleichen der Phasen der jeweiligen der Anzahl von Datenimpulsen mit Einträgen in einer Tabelle, die Datensymbole mit Sätzen von Phasen von Impulsen korreliert.
• Beispiel 41: Verfahren nach einem der Beispiele 39 bis 40, umfassend das Bestimmen deines Standorts zumindest teilweise als Reaktion auf die Anzahl von Entfernungsmessimpulsen.

Additional non-limiting examples of the disclosure include:

• Example 1: A method comprising: receiving an instruction to generate a signal comprising a ranging signal and a data signal; and transmitting, via a terrestrial transmitter for transmitting radio waves with encoded message information and timing information for one or more of positioning, navigation, and timing, the signal responsive at least in part to the instruction, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses subsequent to the number of ranging pulses, respective ones of the number of data pulses having a phase of either a positive going phase or a negative going phase, wherein data is encoded using either the positive going phases or the negative going phases of the data pulses.
• Example 2: The method of example 1, wherein the data comprises a message.
• Example 3: The method of any one of examples 1 to 2, wherein the data comprises time information.
• Example 4: The method of any one of examples 1 to 3, wherein the data comprises a message and time information.
• Example 5: Method according to one of examples 1 to 4, wherein the message is encrypted before encoding in the number of data pulses.
• Example 6: The method of any one of examples 1 to 5, wherein the message includes additional timing information.
• Example 7: The method of any one of examples 1 to 6, wherein the pulse group comprises a pulse length delay between the number of distance measurement pulses and the number of data pulses.
• Example 8: The method of any one of examples 1 to 7, wherein the number of data message pulses comprises a number of data message pulse sets, and each data message pulse set encodes data bits and an error correction bit.
• Example 9: The method of any one of examples 1 to 8, wherein the pulse group includes a pulse length delay between each of the number of data message pulse sets.
• Example 10: The method of any of examples 1 to 9, wherein one or more of the data message burst sets encode at least a portion of a message and one or more of the data message burst sets encode at least a portion of time information.
• Example 11: The method of any one of examples 1 to 10, wherein respective ones of the number of distance measuring pulses have a phase of either a positive-going phase or a negative-going phase, wherein the phases of the respective ones of the number of distance measuring pulses of the respective pulse group correspond to a pulse phase signature, and the pulse phase signature is predefined for a transmission cycle and a terrestrial transmitter.
• Example 12: The method of any one of examples 1 to 11, wherein the pulse phase signature comprises an indication of the phase of each of the number of ranging pulses.
• Example 13: The method of any of examples 1 and 12, wherein the pulse phase signature corresponds to a predefined pulse phase signature schedule comprising a pulse phase signature for a number of transmit cycles.
• Example 14: The method of any one of examples 1 to 13, wherein each of the number of ranging pulses is separated by an interpulse interval, a length of the interpulse interval indicating the terrestrial transmitter.
• Example 15: The method of any of Examples 1 to 14, comprising: receiving a further instruction to generate a further signal; and transmitting, via a further terrestrial transmitter, to transmit radio waves with encoded message information and timing information for one or more of positioning, navigation, and timing, the further signal responsive at least in part to the further instruction, the further signal comprising a pulse group comprising further ranging pulses separated by a further interpulse interval.
• Example 16: Method according to one of examples 1 to 15, wherein a length of the further interpulse interval indicates the further terrestrial transmitter.
• Example 17: The method of any one of examples 1 to 16, wherein transmitting the signal comprises offsetting a start time of the pulse group by a dithering interval.
• Example 18: The method of any of examples 1 to 17, comprising: receiving a further instruction to generate a further signal; and transmitting, via a further terrestrial transmitter, the further signal in response to the received further instruction, the further signal comprising further pulse groups, the further pulse groups having offset start times according to a further dithering interval.
• Example 19: The method of any one of examples 1 to 18, wherein the dithering interval and the further dithering interval are transmitter-level dithering.
• Example 20: The method of any one of examples 1 to 19, wherein the dithering interval and the further dithering interval are chain-level dithering.
• Example 21: The method of any one of examples 1 to 20, wherein the dithering interval and the further dithering interval comprise masked dithering and a dithering interval according to a ramp.
• Example 22: An apparatus comprising: a controller for: generating an instruction to generate a signal comprising a ranging signal and a data signal, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses subsequent to the number of ranging pulses, respective ones of the number of data pulses having a phase of either a positive going phase or a negative going phase, wherein information is encoded using either the positive going phases or the negative going phases of the data signals; and providing the instruction to a terrestrial transmitter for transmitting radio waves comprising encoded message information and timing information for one or more of positioning, navigation, and timing;
• Example 23: An apparatus comprising: an antenna to receive a signal encoding timing information for one or more of positioning, navigation, and timing, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses subsequent to the number of ranging pulses, respective ones of the number of data pulses having a phase of either a positive going phase or a negative going phase, wherein data is encoded using either the positive going phases or the negative going phases of the data signals; and a processor to decode the data at least in part in response to the phases of the respective ones of the number of data pulses.
• Example 24: The apparatus of example 23, wherein the processor is to decrypt the data.
• Example 25: The apparatus of any of examples 23 and 24, wherein the processor is to derive a message from the data.
• Example 26: The apparatus of any of examples 23 to 25, wherein the processor is to provide the message for presentation.
• Example 27: The apparatus of any of examples 23 to 26, wherein the processor is to update the processor's timing information at least in part in response to the data.
• Example 28: Device according to one of examples 23 to 27, wherein the receiver serves to determine a location of the device at least in part in response to the updated timing information.
• Example 29: The apparatus of any of examples 23 to 28, wherein the processor is to derive a message from the data and update timing information of the processor at least in part in response to the data.
• Example 30: The apparatus of any of examples 23 to 29, wherein the processor is to decrypt a portion of the data from which the message is derived.
• Example 31: The apparatus of any of examples 23 to 30, wherein respective ones of the number of ranging pulses have a phase of either a positive going phase or a negative going phase, the phases of the respective ones of the number of ranging pulses of the pulse group corresponding to a pulse phase signature, and wherein the processor is to validate a transmitter of a ranging signal by comparing phases of the number of ranging pulses to the pulse phase signature of the transmitter.
• Example 32: The apparatus of any of examples 23 to 31, wherein the processor is to identify a transmitter of a ranging signal at least in part in response to an interpulse interval, the interpulse interval being a duration of a time separation between the number of ranging pulses.
• Example 33: The apparatus of any of examples 23 to 32, wherein the processor is to: obtain a transmission time of the pulse group; and adjust the calculated transmission time to account for a dithering interval.
• Example 34: The apparatus of any of examples 23 to 33, wherein the receiver is operable to determine a location at least in part in response to the adjusted transmission time.
• Example 35: The apparatus of any of examples 23 to 34, wherein the processor is to determine a location at least in part in response to the number of ranging pulses.
• Example 36: An apparatus comprising: an antenna to receive a signal encoding timing information for one or more of positioning, navigation, and timing, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses, wherein respective ones of the number of data pulses have a phase of either a positive going phase or a negative going phase; and a processor to: observe phases of the respective ones of the number of data pulses; and obtaining data at least in part in response to the phases of the respective ones of the number of data pulses.
• Example 37: The apparatus of example 36, wherein the apparatus comprises a memory for storing a table correlating data symbols with sets of phases of pulses; and wherein the processor is to compare the phases of respective ones of the number of data pulses with entries in the table to obtain the data.
• Example 38: The device of any of examples 36 to 37, wherein the processor is to determine a location of the device at least in part in response to the number of ranging pulses.
• Example 39: A method comprising: receiving a signal encoding timing information for one or more of positioning, navigation, and timing, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses, wherein respective ones of the number of data pulses have a phase of either a positive going phase or a negative going phase; observing phases of the respective ones of the number of data pulses; and obtaining data at least in part in response to the phases of the respective ones of the number of data pulses.
• Example 40: The method of example 39, comprising comparing the phases of each of the number of data pulses with entries in a table correlating data symbols with sets of phases of pulses.
• Example 41: The method of any of examples 39 to 40, comprising determining your location at least in part in response to the number of ranging pulses.

Although the present disclosure has been described herein with respect to certain illustrated examples, those of ordinary skill in the art will recognize and understand that the present invention is not limited thereto. Rather, many additions, omissions, and modifications may be made to the illustrated and described examples without departing from the scope of the invention as claimed below along with its legal equivalents. Moreover, Furthermore, features of one example may be combined with features of another example, but still be included within the scope of the invention contemplated by the inventors.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US63/262729 [0001]
• US63/262728 [0001]
• US 17/447392 [0001]

Claims (19)

An apparatus comprising: an antenna to receive a signal encoding timing information for one or more of positioning, navigation, and timing, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses subsequent to the number of ranging pulses, respective ones of the number of data pulses having a phase of either a positive going phase or a negative going phase, wherein data is encoded using either the positive going phases or the negative going phases of the data signals; and a processor to decode the data at least in part in response to the phases of the respective ones of the number of data pulses. Device according to Claim 1 , where the processor is supposed to decrypt the data. Device according to Claim 1 , where the processor is supposed to derive a message from the data. Device according to Claim 3 , where the processor is to prepare the message for presentation. Device according to Claim 1 , wherein the processor is to update the processor's timing information at least in part in response to the data. Device according to Claim 5 wherein the processor is to determine a location of the device at least in part in response to the updated time information. Device according to Claim 1 , wherein the processor is to derive a message from the data and to update timing information of the processor at least in part in response to the data. Device according to Claim 7 , where the processor is to decrypt a portion of the data from which the message is derived. Device according to Claim 1 , respective ones of the number of ranging pulses have a phase of either a positive going phase or a negative going phase, the phases of the respective ones of the number of ranging pulses of the pulse group corresponding to a pulse phase signature, and wherein the processor is operable to validate a transmitter of a ranging signal by comparing phases of the number of ranging pulses with the pulse phase signature of the transmitter. Device according to Claim 1 wherein the processor is operable to identify a transmitter of a ranging signal at least in part in response to an interpulse interval, the interpulse interval being a duration of a time separation between the number of ranging pulses. Device according to Claim 1 , the processor being operable to: obtain a transmission time of the pulse group; and adjusting the transmission time to account for a dithering interval. Device according to Claim 11 wherein the processor is to determine a location of the device at least in part in response to the adjusted transmission time. Device according to Claim 1 wherein the processor is operable to determine a location of the device at least in part in response to the number of ranging pulses. An apparatus comprising: an antenna to receive a signal encoding timing information for one or more of positioning, navigation, and timing, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses, wherein respective ones of the number of data pulses have a phase of either a positive going phase or a negative going phase; and a processor to: observe phases of respective ones of the number of data pulses; and obtain data at least in part in response to the phases of respective ones of the number of data pulses. Device according to Claim 14 wherein the apparatus comprises a memory for storing a table correlating data symbols with sets of phases of pulses; and wherein the processor is operable to compare the phases of respective ones of the number of data pulses with entries in the table to obtain the data. Device according to Claim 14 wherein the processor is operable to determine a location of the device at least in part in response to the number of ranging pulses. A method comprising: receiving a signal encoding timing information for one or more of positioning, navigation, and timing, the signal comprising a pulse group comprising a number of ranging pulses and a number of data pulses, wherein respective ones of the number of data pulses have a phase of either a positive going phase or a negative going phase; observing phases of respective ones of the number of data pulses; and obtaining data at least in part in response to the phases of respective ones of the number of data pulses. Procedure according to Claim 17 , comprising comparing the phases of each of the number of data pulses with entries in a table correlating data symbols with sets of phases of pulses. Procedure according to Claim 17 comprising determining a location at least in part in response to the number of ranging pulses.

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