CN114942456B - Single-frequency differential GNSS receiver applying different relevant distance pseudo-range observables - Google Patents

Abstract

The invention discloses a single-frequency differential GNSS receiver applying different relevant distance pseudo-range observables, which comprises an antenna interface, a radio frequency module, a baseband and data processing module, a communication module and a power supply and clock module. The invention respectively tracks satellites by using the reference spacing and the flowing spacing to obtain mutually independent pseudo-range observables, performs positioning calculation and pseudo-range correction calculation by using the reference spacing pseudo-range, and sends the calculated pseudo-range observables to the flowing spacing to perform pseudo-range differential positioning calculation. According to the invention, the pseudo range observables of different relevant distances are adopted to carry out differential positioning calculation, so that the pseudo range differential positioning of the single receiver is realized, the positioning reliability and stability of the existing single frequency receiver are improved, and the communication equipment required by the pseudo range differential positioning is eliminated.

Description

Single frequency differential GNSS receiver using pseudorange observations with different correlation spacings

Technical Field

The present invention relates to the field of detection instruments and equipment, and in particular to a single-frequency differential GNSS receiver using pseudo-range observation quantities with different correlation intervals.

Background Art

GNSS receiver is the abbreviation of Global Navigation Satellite System. There are many types of GNSS receivers, which can be divided into navigation receivers, surveying receivers and timing receivers.

GNSS receivers usually include the following parts: antenna, RF front end, baseband processing, positioning solution and receiver housing. Existing receiver tracking uses a single correlation interval to track all visible satellites to obtain a set of satellite observations and navigation messages. There are three main types of existing positioning solutions: single point positioning (SPP), differential positioning (DGNSS), and precise single point positioning (PPP). Differential positioning can be divided into pseudo-range differential positioning (RTD) and carrier phase differential positioning (RTK) according to the different application observations.

The existing positioning algorithms of GNSS receivers have different accuracy. The three-axis positioning accuracy of SPP is 10m. Its feature is that it can realize real-time dynamic positioning function without any other auxiliary information. The disadvantage is that the positioning accuracy is not high enough. The existing single-receiver single-frequency positioning algorithm is only SPP. The three-axis positioning accuracy of DGNSS can reach the sub-meter level, but it requires auxiliary information from local base stations or network base stations, and also requires auxiliary information receiving equipment (usually radio communication equipment). PPP has the highest positioning accuracy and can achieve positioning accuracy of centimeters to decimeters, but it also needs to receive external auxiliary information, precise ephemeris, precise clock error, etc. At present, the dynamic performance of PPP needs to be improved.

Summary of the invention

The present invention aims at the shortcomings of the existing single-frequency GNSS receiver and proposes a single-frequency differential GNSS receiver using pseudo-range observations with different correlation intervals. Since DGNSS requires additional auxiliary information and communication equipment, this leads to the need for additional costs for differential positioning, which restricts the application of DGNSS. In order to solve the problem of low SPP positioning accuracy and the need for additional costs for DGNSS, the present invention proposes a single-frequency differential GNSS receiver using pseudo-range observations with different correlation intervals.

A single-frequency differential GNSS receiver for pseudorange observations using different correlation spacings provided in an embodiment of the present invention is suitable for a navigation receiver. The receiver includes an antenna interface connected to an antenna, a radio frequency module, a baseband and data processing module, a communication module, and a power supply and clock module. The antenna interface is connected to the radio frequency module, the radio frequency module is connected to the baseband and data processing module, the baseband and data processing module is connected to the communication module, and the power supply and clock module is connected to the radio frequency module, the baseband and data processing module, and the communication module. The baseband and data processing module includes a reference spacing baseband processing module, a mobile spacing baseband processing module, a reference spacing data processing module, and a mobile spacing data processing module; the communication module encodes and outputs the positioning result obtained by data processing calculation through a serial port. The power supply and clock module provides a power supply reference clock for other modules, and the clock includes a local crystal oscillator and an external clock interface;

The radio frequency module is used to receive the high frequency signal of the antenna, perform down-conversion and analog-to-digital conversion to obtain a digital intermediate frequency signal, and send the intermediate frequency signal to the baseband and data processing module.

The baseband and data processing modules are used to process digital intermediate frequency signals. The reference spacing baseband processing module applies the reference spacing to perform signal tracking, obtains the reference spacing pseudorange observations and satellite navigation messages of all satellites, and sends the satellite reference spacing pseudorange observations to the reference spacing data processing module, and sends the satellite navigation messages to the reference spacing signal processing module and the mobile spacing data processing module; the reference spacing data processing module performs reference spacing positioning solution and pseudorange correction amount calculation, and sends them to the mobile spacing data processing module; the mobile spacing baseband processing module applies the mobile spacing to perform signal tracking, obtains the mobile spacing pseudorange observations of all satellites, and sends them to the mobile spacing data processing module; the mobile spacing data processing module performs mobile spacing pseudorange correction and pseudorange differential positioning, and sends the differential positioning result to the communication module.

The communication module is used to receive the positioning results of the baseband and data processing modules and encode the positioning results through serial port technology, and then output them.

The power supply and clock module is used to provide power supply and clock reference for the RF module, baseband and data processing module, and communication module. The clock module can use a local temperature compensated crystal oscillator to provide clock for other modules and has an external clock interface. It can connect an external high-stability clock to provide a clock reference for other modules.

In order to achieve the above-mentioned invention purpose and solve the problems existing in the prior art, the technical solution adopted by the present invention is: a single-frequency GNSS receiver using pseudo-range observations with different correlation intervals. The working process of the receiver is divided into the following steps:

Step 1: Connect the antenna and receiver, power on the receiver, and the receiver starts working. The power supply and clock module provide the receiver with a clock reference and a stable power supply, and the RF front end receives the high-frequency data transmitted by the antenna.

Step 2: The RF module receives the antenna signal, performs down-conversion and analog-to-digital conversion on the antenna signal to obtain a digital intermediate frequency signal;

Step 3: baseband processing and data processing, receiving the digital intermediate frequency signal, and performing baseband signal processing and data processing;

Step 3.1, baseband processing of the reference spacing, using the reference spacing to track all satellites, and obtaining the reference spacing pseudo-range observations and satellite navigation messages of all satellites;

Step 3.2: Mobile spacing baseband processing: using mobile spacing to track all satellites to obtain mobile spacing pseudo-range observations of all satellites;

Step 3.3, benchmark spacing data processing, using benchmark spacing pseudorange observations and navigation messages to perform single-point positioning, obtain benchmark spacing position information, and calculate satellite pseudorange corrections;

Step 3.4, flow spacing data processing, using flow spacing pseudorange observations, navigation messages and pseudorange corrections to perform positioning and obtain flow spacing positions;

Step 4: Output pseudo-range differential positioning results. The communication module outputs the current reference spacing position information, pseudo-range correction information, flow spacing differential position information and time information through the RS232 serial port. The output data starts encoding the data message with an agreed frame header, and the data message to be sent is encoded in the form of each data content occupying 4 bytes. Finally, the data check bit is used as the tail frame. The check method uses the serial port parity check mode to complete the data encoding and send it through the serial port.

The beneficial effects of the present invention are:

First, the present invention uses pseudo-range observations with different correlation spacings to realize a GNSS receiver capable of single-frequency pseudo-range differential positioning, thereby reducing the number of receivers required for pseudo-range differential positioning to one;

Second, the present invention uses the reference spacing and the mobile spacing to track the same satellite respectively, and can obtain the reference spacing pseudo-range observations and the mobile spacing pseudo-range observations of the same satellite that are independent of each other, thereby increasing the number of pseudo-range observations of the single-frequency receiver under the premise of increasing the number of receivers;

Third, the present invention uses the reference spacing positioning result to calculate the pseudo-range correction value, and directly transmits it to the mobile spacing for data processing, without the need for additional communication equipment, thereby reducing the cost of pseudo-range differential positioning;

Fourth, the single-frequency differential GNSS receiver using pseudo-range observations with different correlation spacings of the present invention improves the accuracy, stability and reliability of single-receiver single-frequency positioning. Due to the adoption of the above technical solution, the present invention provides a single-frequency differential GNSS receiver using pseudo-range observations with different correlation spacings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic structural diagram of a single-frequency differential GNSS receiver for pseudorange observations using different correlation spacings according to the present invention;

FIG2 is a hardware structure diagram of a single-frequency differential GNSS receiver using pseudo-range observations with different correlation spacings according to the present invention;

FIG3 is a schematic diagram of a single-frequency differential GNSS receiver for pseudo-range observations using different correlation spacings according to the present invention;

FIG4 is a schematic diagram of the appearance of a single-frequency differential GNSS receiver for pseudorange observations using different correlation spacings according to the present invention.

DETAILED DESCRIPTION

To make the technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention:

In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Fig. 1 is a schematic diagram of the structure of a single-frequency differential GNSS receiver for pseudo-range observation using different correlation intervals provided by an embodiment of the present invention, which is applicable to a navigation receiver. The receiver includes an antenna interface 101 connected to an antenna, a radio frequency module 102, a baseband and data processing module 103, a communication module 104, and a power supply and clock module 105. The antenna interface 101 is connected to the radio frequency module 102, the radio frequency module 102 is connected to the baseband and data processing module 103, the baseband and data processing module 103 is connected to the communication module 104, the communication module 104 uses serial communication technology to output the positioning result obtained by data processing through encoding, and the power supply and clock module 105 is connected to the radio frequency module 102, the baseband and data processing module 103, and the communication module 104. The baseband and data processing chip 103 includes a reference interval baseband processing module, a mobile interval baseband processing module, a reference interval data processing module, and a mobile interval data processing module; the power supply clock module 105 provides power and clock for other modules, and the clock module includes a local crystal oscillator and an external clock interface;

The RF module 102 is used to receive the high frequency signal of the antenna, and perform down-conversion and analog-to-digital conversion to obtain a digital intermediate frequency signal, and send the intermediate frequency signal to the baseband and data processing module 103. The RF front end can receive L1 frequency band data of GPS, BDS, Galileo, and GLONASS systems to perform single-frequency data down-conversion and analog-to-digital conversion;

The baseband and data processing module 103 is used to process digital intermediate frequency signals. The reference spacing baseband processing module applies the reference spacing to perform signal tracking, obtains the reference spacing pseudorange observations and satellite navigation messages of all satellites, and sends the satellite reference spacing pseudorange observations to the reference spacing data processing module, and sends the satellite navigation messages to the reference spacing signal processing module and the mobile spacing data processing module; the reference spacing data processing module performs reference spacing positioning solution and pseudorange correction calculation, and sends them to the mobile spacing data processing module; the mobile spacing baseband processing module applies the mobile spacing to perform signal tracking, obtains the mobile spacing pseudorange observations of all satellites, and sends them to the mobile spacing data processing module; the mobile spacing data processing module performs mobile spacing pseudorange correction and pseudorange differential positioning, and sends the differential positioning result to the communication module 104.

The communication module 104 is used to receive the positioning result of the baseband and data processing module 103 and encode the positioning according to a preset encoding method, and output the encoded positioning result through serial port technology.

The power supply and clock module 105 is used to provide power supply and clock reference for the RF module 102, the baseband and data processing module 103, and the communication module 104. The clock module 105 can use the local temperature compensated crystal oscillator to provide clocks for other modules, and has an external clock interface, which can be connected to an external high-stability clock to provide clock references for other modules.

Figure 2 is a hardware structure diagram of a single-frequency differential GNSS receiver for pseudo-range observations with different correlation spacings provided by an embodiment of the present invention. As mentioned above, the antenna interface is an SMA reverse polarity male connector, the RF module is a Max2769 with a built-in analog-to-digital conversion function and its peripheral circuits, the baseband and data processing module is a ZYNQ-7020 chip of Xilinx, the FPGA logic gate circuit of ZYNQ-7020 performs baseband processing, including a reference spacing baseband processing module and a mobile spacing baseband processing module, the ARM core of ZYNQ-7020 performs reference spacing data processing and mobile spacing data processing, the communication module is an RS232 serial port, the clock module is a 10MHz temperature-compensated crystal oscillator, the external clock interface is an SMA reverse polarity male connector, and the power supply is a 3.3V DC power supply stabilized by an LM117 chip.

The RF module in the specific example of the present invention down-converts the high-frequency satellite signal received by the antenna into an analog intermediate frequency signal through the Max2769 chip, and then performs analog-to-digital conversion on the analog intermediate frequency signal, and outputs a 16.368MHz in-phase (I) branch 2-bit sampling digital intermediate frequency signal to the ZYNQ7020 chip of the baseband and data processing module.

The ZYNQ7020 chip in the example of the present invention includes a field programmable logic gate circuit (FPGA) and a RISC (reduced instruction set computer) microprocessor (ARM) core, wherein the FPGA is used for base spacing and flow spacing baseband processing, and the ARM core is used for base spacing and flow spacing data processing.

The RS232 serial port tool in the example of the present invention receives the positioning result of the ZYNQ7020 chip, encodes the output data starting with an agreed header frame, encodes the sent data message in the form of each data content occupying 4 bytes, and finally uses the data check bit as the tail frame. The check method uses the serial port parity check mode to complete the data encoding and send it through the serial port.

The 10MHz temperature-compensated crystal oscillator in the example of the present invention provides a reference local clock for the receiver, and the LM117 voltage regulator chip provides a DC regulated power supply for other modules.

The working process of the single-frequency differential GNSS receiver using pseudo-range observations with different correlation spacings is further described below in conjunction with FIG3. FIG3 is a schematic diagram of the principle structure of the receiver of the present invention. The receiver of the present invention works according to the following steps:

Step 1: Connect the antenna and receiver, power on the receiver, and the receiver starts working. The RF front end receives the high-frequency data transmitted by the antenna.

Step 2: The RF module receives the antenna signal, performs down-conversion and analog-to-digital conversion on the antenna signal to obtain a digital intermediate frequency signal;

Step 3: Baseband processing and data processing: receiving digital intermediate frequency signals, performing baseband signal processing and data processing. The baseband is used for signal demodulation, demodulating navigation messages, code observations (pseudoranges) and carrier observations from the intermediate frequency signals, and performing pseudorange differential positioning using navigation messages and code observations for data processing.

Step 3.1, baseband processing of the reference spacing, using the reference spacing to track all satellites, and obtaining the reference spacing pseudo-range observations and satellite navigation messages of all satellites;

Step 3.2: Mobile spacing baseband processing: using mobile spacing to track all satellites to obtain mobile spacing pseudo-range observations of all satellites;

Step 3.3: Process the reference spacing data. Apply the reference spacing pseudorange observations and navigation messages to perform single-point positioning to obtain reference spacing position information; calculate the satellite pseudorange correction

Step 3.4, flow spacing data processing, using flow spacing pseudorange observations, navigation messages and pseudorange corrections to perform positioning and obtain flow spacing positions;

Step 4: Output pseudo-range differential positioning results. The communication module outputs the current reference spacing position information, pseudo-range correction information, flow spacing differential position information and time information through the RS232 serial port.

FIG4 is a schematic diagram of a receiver provided in an example of the present invention, wherein the receiver includes a receiver housing, a power interface, a communication interface, an external clock interface and an antenna interface.

The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims (6)

1. A single-frequency differential GNSS receiver employing pseudorange observations of different relative distances, characterized by: positioning single-frequency pseudo-range difference of a single receiver, wherein the single-frequency pseudo-range difference comprises an antenna interface, a radio frequency module, a baseband and data processing module, a communication module and a power supply and clock module;

The antenna interface is connected with the radio frequency module, the radio frequency module is connected with the baseband and data processing module, the baseband and data processing module is connected with the communication module, and the power supply and clock module is connected with the radio frequency module, the baseband and data processing module and the communication module;

The radio frequency module is used for receiving the high-frequency signal of the antenna, performing down-conversion and analog-to-digital conversion to obtain a digital intermediate frequency signal, and transmitting the intermediate frequency signal to the baseband and data processing module;

The baseband and data processing module processes the digital intermediate frequency signals and comprises a reference space baseband processing module, a flow space baseband processing module, a reference space data processing module and a flow space data processing module;

The reference space baseband processing module performs signal tracking based on the reference space to obtain reference space pseudo-range observed quantity and satellite navigation messages of all satellites, transmits the satellite reference space pseudo-range observed quantity to the reference space data processing module, and transmits the satellite navigation messages to the reference space signal processing module and the mobile space data processing module; the reference spacing data processing module performs reference spacing positioning calculation and pseudo-range correction calculation and transmits the calculation and pseudo-range correction to the flowing spacing data processing module; the mobile space baseband processing module performs signal tracking by adopting the mobile space, obtains mobile space pseudo-range observables of all satellites, and transmits the mobile space pseudo-range observables to the mobile space data processing module; the mobile spacing data processing module carries out mobile spacing pseudo-range correction and pseudo-range differential positioning and sends a differential positioning result to the communication module;

The communication module is used for receiving the positioning result output by the baseband and data processing module, encoding the positioning result through a serial port technology and outputting the positioning result;

The power and clock module provides a power reference clock for the system.

2. The single-frequency differential GNSS receiver of claim 1 wherein: and the reference space baseband processing module tracks all satellites and obtains reference space pseudo-range observables and satellite navigation messages.

3. The single-frequency differential GNSS receiver of claim 1 wherein: and the flow interval baseband processing module tracks all satellites to obtain flow interval pseudo-range observables.

4. The single-frequency differential GNSS receiver of claim 1 wherein: and the reference spacing data processing module tracks all satellites and obtains reference spacing pseudo-range observables and satellite navigation messages.

5. The single-frequency differential GNSS receiver of claim 1 wherein: the flow interval data processing module adopts the flow interval pseudo-range observed quantity and the pseudo-range correction quantity to carry out pseudo-range difference resolving calculation.

6. The single-frequency differential GNSS receiver of claim 1 wherein: and the communication module encodes and outputs the differential positioning result of the receiver.