FR3150872A1 - Method for calculating and/or monitoring the operation of a satellite positioning system on board a vehicle, and associated device and computer program product - Google Patents

Abstract

TITLE Method for calculating and/or monitoring the operation of a satellite positioning system embedded in a vehicle, and associated device and computer program product The present invention relates to a method for calculating and/or monitoring the operation of a satellite positioning system of a vehicle in a geographical area comprising the following steps: - acquisition of spatial and temporal observation coordinates; - acquisition of spatio-temporal coordinates of the satellites; - acquisition of characteristics and spatio-temporal coordinates representative of known positions of interference sources; - acquisition of data representative of characteristics of the satellite positioning system; - calculation of an impact of the interference sources on the operation of the satellite positioning system for each service and constellation of the GNSS system and for each spatial and temporal observation coordinate as a function of the spatial observation coordinate, the observation temporal coordinate, the spatio-temporal coordinates representative of the known positions of the interference sources. Figure 2

Description

Method for calculating and/or monitoring the operation of a satellite positioning system on board a vehicle, and associated device and computer program product

The present invention relates to a method for calculating and/or monitoring the operation of a satellite positioning system on board a vehicle which must operate in a geographical area and within a time range.

The present invention also relates to a computer program product and an associated calculation and/or monitoring device.

Vehicles of all types, in particular aerial, land or naval vehicles, are equipped with a so-called satellite positioning system because it is generally based on a satellite positioning receiver and an antenna. This system can also be equipped with other additional positioning assistance sensors such as inertial units, Doppler sensors, radio navigation, etc. in the event of loss of capacity or performance of the satellite positioning receiver. The satellite positioning system is a set of components based on a constellation of satellites making it possible to provide a user, via the sensors constituting it, with their 3D position, 3D speed and time. The satellite positioning system thus allows positioning, navigation and time measurement (Positioning, Navigation, Time: PNT) and thus constitutes a so-called PNT system. In the field of civil aviation, satellite positioning receivers are essential for operational safety, as they allow aircraft to have constant geolocation, time and navigation capacity in a precise and integrated manner with global and permanent coverage.

In the field of civil aviation, satellite positioning receivers are used at all levels: by aircraft for their navigation system, by aviation communication, navigation and surveillance (CNS) systems, by air traffic management (ATM).

Similarly, the use of drones (English: Unmanned Aerial Vehicle, UAV) equipped with satellite positioning receivers is constantly increasing. These drones widely exploit the satellite positioning system. Their applications are increasingly numerous: commercial delivery, logistical support in surveillance, security or emergency services... and require surveillance and control by the management of drone air traffic (English: UAV Traffic Management, UTM).

The weakness of these satellite positioning receivers is their vulnerability to radio frequency interference. In the presence of interference, their performance and ability to provide valid and intact PNT depends on many parameters, such as the quality of the receiver itself, but also on-board protection devices (e.g. filtering), the power and number of satellite signals and interferences received, the waveforms and frequencies of the interferences, the positioning of the transmitters and the 4D trajectory of the vehicle.

In recent years, incidents of disruption to the satellite positioning system due to interference sources have increased sharply (in 2022, an increase of more than 2,000% compared to 2018), most of them affecting en route flights.

The existence of sources of interference (radio frequency interference; English Radio Frequency Interference, RFI) including unintentional sources of interference and/or intentional protection jammers have the effect of degrading the performance of the satellite positioning system, or even making certain capabilities of the receivers used unavailable, such as acquisition, tracking, integrity, dual-frequency or multi-constellation processing, use of an augmentation system (ABAS), etc. These sources of interference, in particular intentional protection jammers, may be particularly numerous near certain conflict zones for example.

Even though aircraft can fly safely without satellite positioning systems thanks to additional sensors, the massive increase in interference sources rapidly reduces the efficiency of the entire aviation system, which imposes a greater workload on pilots and air traffic controllers (location verification, radar tracking), and requires the maintenance of additional communication, navigation and surveillance services to meet more stringent requirements. 38.5% of European en-route traffic passes through regions intermittently but regularly affected by interference sources that pose a potential risk to flight safety.

As a result, the sources of interference have a direct and harmful impact on an aeronautical world which nevertheless constantly aspires to guarantee better safety.

From WO 2015/065664 A1 a system is known for generating a visual representation of interference sources that impair the operation of a satellite positioning system. The visual representation may comprise a map overlaid with visual indicators indicating a location and magnitude of the interference.

However, the known system does not make it possible to determine the impact of interference sources on the operation of a particular satellite receiver and on the on-board positioning system, nor the impact on the performance and capabilities of the latter in a vehicle that must operate in a defined geographical area and at different altitudes. The known system also does not make it possible to determine the impact of interference sources on the operation of a satellite receiver at a specific date and time. Thus, the system does not make it possible to predict or estimate the risks of malfunction of the on-board satellite positioning receiver when the vehicle is located at specific positions in the geographical area at a specific time. Similarly, the known system also does not make it possible to determine the impact of interference sources on the operation of a satellite positioning system on board a vehicle that must follow a flight plan or a particular route at a specific date and time. Finally, such a system does not make it possible to reduce the risks of malfunction by proposing a flight plan or a 4D route ensuring proper operation of the on-board satellite positioning system.

The aim of the invention is then to propose a calculation and/or monitoring method making it possible to predict or reduce the risks of malfunction of the satellite positioning system used when the vehicle must move in a geographical area, at various altitudes and in a given time slot, in particular when the vehicle must follow a planned 4D route crossing the geographical area.

For this purpose, the invention relates to a method for calculating and/or monitoring the operation of a satellite positioning system of a vehicle in a geographical area, the operation of said positioning system including the integrity, capacities and performances of this system, the method comprising the following steps:

- acquisition of spatial and temporal observation coordinates, the spatial observation coordinates being located in the geographic area;

- acquisition of spatio-temporal coordinates of the satellites of a GNSS system for each observation temporal coordinate;

- acquisition of characteristics and spatio-temporal coordinates representative of known positions of sources of interference of a GNSS system signal, located in or near the geographical area;

- acquisition of data representative of characteristics of the satellite positioning system;

- calculation of the impact of interference sources on the operation of the satellite positioning system for each service and constellation of the GNSS system and for each spatial and temporal observation coordinate as a function of the spatial observation coordinate, the temporal observation coordinate corresponding to this spatial observation coordinate, the spatio-temporal coordinates of the satellites of the GNSS system at the temporal observation coordinate, the spatio-temporal coordinates representative of the known positions of the interference sources at the temporal observation coordinate and the data representative of characteristics of the satellite positioning system.

The method according to the invention thus makes it possible, for a path defined in space and time, to precisely determine the impact of interference sources on the operation and performance of the satellite positioning system of a vehicle moving in the geographical area. Thus, the method according to the invention makes it possible to predict or reduce the risks of malfunction of the satellite positioning system precisely when the vehicle follows the planned path.

According to other advantageous aspects of the invention, the calculation and/or monitoring method comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

- the method further comprises the following steps:

- obtaining a planned trajectory of the vehicle, the planned trajectory connecting a starting position to a destination of the vehicle and comprising a departure date of the vehicle or the planned trajectory connecting a current position of the vehicle to the destination of the vehicle and comprising a current date; and

- determination of the spatial and temporal coordinates of observation located on the planned trajectory of the vehicle at a date estimated from the departure date of the vehicle or from the current date and an estimated travel time for this spatial coordinate from the departure position of the vehicle or from the current position to this spatial coordinate.

- the planned trajectory of the vehicle is obtained:

- by calculating several possible trajectories of the vehicle connecting either the starting position to the destination or the current position to the destination;

- by determining spatial and temporal observation coordinates located on several possible trajectories of the vehicle at an estimated date from the departure date of the vehicle or from the current date and an estimated travel time for this spatial observation coordinate and this possible trajectory from the departure position of the vehicle or from the current position to this spatial observation coordinate;

- by acquiring the spatio-temporal coordinates of the GNSS system satellites for each observation time coordinate of each possible trajectory;

- by calculating, for each possible trajectory, the impact of the interference sources on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates as a function of the spatial observation coordinate, the temporal observation coordinate associated with this spatial observation coordinate, the spatio-temporal coordinates of the satellites of the GNSS system at the temporal observation coordinate, the spatio-temporal coordinates representative of known positions of the interference sources and the data representative of characteristics of the satellite positioning system;

- by determining the planned trajectory among the possible trajectories based on the impact of interference sources on the operation of the satellite positioning system at each spatial and temporal observation coordinate located on the possible trajectory;

- for each possible trajectory and/or for the planned trajectory or for any point in the geographical area, the calculation of the impact of interference sources on the operation of the satellite positioning system includes the calculation of the distances, elevations and azimuths of each interference and of each satellite of the GNSS system at each of the spatial and temporal observation coordinates of the possible trajectory and/or of the planned trajectory and/or of the geographical area;

- the method further comprises the following step:

- acquisition of data representative of a vehicle category and/or a vehicle shape and/or a position of the antenna on the vehicle and/or vehicle movement characteristics;

- said impact on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates is calculated based on an antenna gain of the vehicle antenna estimated for each spatial and temporal observation coordinate, from data representative of the vehicle category and/or the shape of the vehicle and/or the position of the antenna on the vehicle and/or an orientation of the vehicle at this spatial and temporal observation coordinate estimated on the basis of data representative of the movement characteristics;

- the method further comprises the following step:

- acquisition of data representative of the topography and obstacles of the geographical area;

- said impact on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates is further calculated based on data representative of a topography of the geographical area;

- the vehicle being an aircraft, the method being characterized by the following step:

- acquisition of data representative of air corridors located in the geographical area;

- the possible trajectories of the aircraft connecting either the starting position to the destination or the current position to the destination are further calculated from data representing the air corridors, the possible trajectories essentially following the air corridors;

- the acquisition of spatial coordinates representative of known positions of interference sources is repeated at regular intervals;

- the method further comprises the following step:

- division of the planned trajectory into a plurality of sections determined according to the impact of the interference sources on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates located on the respective section, in particular if the section is a section with a high disturbance forecast or a section with a low disturbance forecast;

- the method further comprises the following step:

- warning a driver and/or vehicle crew when the current vehicle position is approaching a section with high disruption forecast, and/or in the event of loss of capacity and/or degradation of performance;

- the method further comprises the following steps:

- verification of proper functioning, performance and capabilities of the vehicle positioning system at regular time intervals with respect to predictions;

- if the deviation from the predictions is greater than a threshold, generation of a message updating a database of spatial coordinates representative of the known positions of interference sources in the geographic area.

- the geographic area is divided into a plurality of boxes constituting a grid, the grid preferably comprising a predefined resolution, the spatial and temporal observation coordinates comprising a plurality of positions each located in one of the boxes constituting the grid, preferably located in the center of the box constituting the grid, the geographic area observed for the same instant in time, the spatial and temporal observation coordinates all referring to the same instant of observation.

The invention also relates to a computer program product comprising software instructions which, when executed by a computer, implement the calculation and/or monitoring method, as defined above.

The invention also relates to a device for calculating and/or monitoring the operation of a satellite positioning system of a vehicle in a geographical area, comprising technical means adapted to implement the calculation and/or monitoring method, as defined above.

The invention will appear more clearly on reading the description which follows, given solely as a non-limiting example, and made with reference to the drawings in which:

there is a schematic representation of a device for calculating and/or monitoring the operation of a satellite positioning system of a vehicle in a geographical area according to the present application;

there is a schematic representation of several possible flight plans of a vehicle crossing a geographic area;

there is a representation of a power received from an interference source in the geographic area in a given frequency band and at a given time and altitude;

there is a representation of a received power from the interference source after applying the on-board satellite antenna pattern to the vehicle in the geographic area;

there is a representation of the total noise power spectral density present in a particular receiver (after rejection, filtering, correlation, etc.) with respect to three interference sources in the geographic area for three services of a satellite positioning system;

there :

- part A is a representation of the estimated powers of the signals of the satellite positioning system received over time at a given spatial point in the geographic area and for a given service (e.g. L1 C/A);

- part B is a representation of the antenna gain applied to each satellite signal received by the satellite positioning system at the point located in the geographic area;

- Part C is a representation of the estimated post-antenna power of each signal received by the satellite positioning system at the point located in the geographic area;

there is a representation of the estimated capabilities of the satellite positioning system receiver with respect to three services and for the entire geographic area at a given time t and altitude;

there is a schematic representation of a planned trajectory of the vehicle divided into a plurality of segments according to the estimated capacities;

there is a representation of a power received at the antenna from an interference source along a 4D trajectory crossing the geographic area;

there is a representation of a post-antenna power received from the interference source along the 4D trajectory crossing the geographic area; and

there :

- part A is a representation of an estimated power of the satellite signals of a given service received at the antenna of a satellite positioning system of a vehicle moving along a 4D trajectory crossing the geographical area;

- part B is a representation of the antenna gains applied to each satellite signal received along the 4D trajectory crossing the geographic area;

- part C is a representation of the estimated post-antenna power of each GNSS system signal received along the 4D trajectory crossing the geographic area,

There illustrates a device 10 for calculating and/or monitoring the operation of a satellite positioning system for a vehicle in a geographic zone Z.

This device 10 is suitable for implementing a method of calculating and/or monitoring the operation of the satellite positioning system of the vehicle in the geographical zone Z. The calculating and/or monitoring device 10 comprises an input module 20, a processing module 30 and an output module 40.

By operation of the satellite positioning system, we mean both the integrity of this system, i.e. its ability to provide data on an output, but also its capabilities, including its ability to acquire a signal emitted by one or more satellites, its ability to track this signal or to find this signal, as well as its performance when it is able to at least acquire a signal, in particular in terms of precision of the PNT and speed of the measurement chain, this speed depending in particular on the time taken to lock on to a satellite signal as well as the response time of the system to an acquired signal.

The input module 20 and the output module 40 each comprise at least one communication interface allowing an exchange of information with a data processing device such as a server or a user interface UI for example.

The processing module 30 is for example in the form of one or more software programs stored in a memory and executable by one or more processors. Alternatively or in addition, the processing module 30 is at least partially in the form of a programmable logic circuit, such as an FPGA (Field-Programmable Gate Array) type circuit.

Alternatively, when the method is carried out in the form of one or more software programs, i.e. in the form of a computer program, also called a computer program product, it is also capable of being recorded on a medium, not shown, that is readable by a computer. The computer-readable medium is, for example, a medium capable of storing electronic instructions and of being coupled to a bus of a computer system. For example, the readable medium is an optical disk, a magneto-optical disk, a ROM memory, a RAM memory, any type of non-volatile memory (for example FLASH or NVRAM) or a magnetic card. A computer program comprising software instructions is then stored on the readable medium.

The calculation and/or monitoring device 10 allows the implementation of the method for calculating and/or monitoring the operation of the satellite positioning system of the vehicle in the geographical zone Z. The geographical zone Z can be a fixed, extensible or mobile geographical zone. It can also be a corridor around a flight plan or a trajectory. In the following, when “in the vicinity of the geographical zone Z” is mentioned, it means an extended geographical zone including the geographical zone Z. This extended geographical zone can for example be defined by a border distant from the border delimiting the geographical zone Z by a predetermined distance.

The geographic area Z may be divided into a plurality of cells constituting a grid. The grid may have a predefined resolution. When the method performs a step for any point in the geographic area, the step may be performed, for each cell, on a point located in the cell, preferably at the center of the cell. The geographic area may thus be rasterized.

The vehicle is provided with at least one satellite positioning system comprising a receiver, an antenna connected to the receiver and, in some examples, one or more anti-interference robustness devices. The receiver makes it possible to determine its position and/or its speed of movement, i.e. also the position of the vehicle and/or the speed of movement of the vehicle on the basis of GNSS signals that it receives from navigation satellites. Each receiver may have its own characteristics and exploit one or more GNSS services. In some examples, the satellite positioning system further comprises one or more additional positioning assistance sensors such as inertial units, Doppler sensors, radio navigation, etc.

Navigation satellites are part of a GNSS system which can be a GPS, Galileo, Glonass, Beidou, SBAS system for example offering several services (for example L1 C/A, L2C) transmitted on different frequency bands.

The calculation and/or monitoring method comprises a step of acquiring spatial and temporal observation coordinates, the spatial observation coordinates being located in the geographic zone Z.

The observation spatial and temporal coordinates comprise an observation spatial coordinate defining a point in the geographic area and an observation temporal coordinate associated with the observation spatial coordinate defining an instant in time. Preferably, the observation spatial coordinates are three-dimensional coordinates. The observation temporal coordinate among the acquired observation temporal coordinates occurring first in time and the observation temporal coordinate among the acquired observation temporal coordinates occurring last in time may define an observation time range. The observation spatial coordinate may correspond to a position of the vehicle expected for an instant corresponding to the observation temporal coordinate associated with this observation spatial coordinate.

Alternatively, the observation time range can be defined by the user by entering a time point marking the start of the observation time range and a time point marking the end of the observation time range.

The user may be a driver of the vehicle, a member of the vehicle crew and/or a person in charge of journey planning (route, flight plan) or traffic safety (air, sea) for example.

The calculation and/or monitoring method comprises a step of acquiring spatio-temporal coordinates of the satellites of the GNSS system for each observation time coordinate. The spatio-temporal coordinates of the satellites can be acquired by retrieving them from a GNSS database BDGNSS where they have been previously deposited. The spatio-temporal coordinates of the satellites can also be acquired by retrieving them from a memory of the receiver or a memory of the calculation and/or monitoring device 10 where they have been previously deposited.

The space-time coordinates of satellites can be, for example, almanac data or ephemeris data. Almanac data and ephemeris data provide the position of navigation satellites in the sky at a given date, as one of the observation time coordinates. Ephemeris data provide more precise position data than almanac data. Ephemeris data are usually stored in a database that is periodically updated to take into account changes in the satellite orbit.

The GNSS database BDGNSS may include a constellation management system collecting almanac data and/or ephemeris data. The constellation management system may also monitor and/or record the levels of the received GNSS signals in order to deduce the powers emitted for each service by each satellite (calibration) and thus improve the accuracy of the predictions of the levels of the received GNSS signals in the geographical area Z.

From the almanac and/or ephemeris data, the calculation and/or monitoring method and the calculation and/or monitoring device 10 can make the prediction for each constellation of visible and healthy satellites, of the distance/elevation/azimuth of each from any point in the geographic zone Z and during the entire desired observation time range.

By determining the position of the visible satellites and, where appropriate, the measurements taken that can serve as calibration, the method can implement a step of calculating the distance and the power received from each visible satellite at any point in the geographical zone Z and over the entire observation time range defined by using propagation models. In particular, the method can implement a step of calculating the distance and the power received from each visible satellite for each spatial and temporal observation coordinate. These propagation models can take into account a loss of intensity of the GNSS signal during the propagation of the GNSS signal depending on the presence of a free space located between the receiver and the satellite and/or ionospheric propagation phenomena and/or masking by the terrain and/or masking by buildings.

The calculation and/or monitoring method comprises a step of acquiring spatial coordinates representative of known positions of interference sources of a signal of the GNSS system covering the geographical zone Z. The spatial coordinates representative of known positions of interference sources can be acquired by retrieving them from a database where they have been previously deposited, such as an RFI BDRFI database. According to one possibility, the acquisition of the spatial coordinates representative of known positions of interference sources can be repeated at regular intervals.

The calculation and/or monitoring method may further comprise a step of acquiring the spectrum (central frequency, bandwidth) and the waveform and/or modulation type of the interference signal emitted by each known interference source and/or an average power of the interference signal emitted by each known interference source in the geographical area Z and/or a minimum power of the interference signal emitted by each known interference source in the geographical area Z and/or a maximum power of the interference signal emitted by each known interference source in the geographical area Z. The spectrum, the waveform and the modulation type of the interference signal and/or the average power of the interference signal and/or the minimum power of the interference signal and/or the maximum power of the interference signal may be acquired by retrieving it/them from a database where it/them has/have been previously deposited, such as the RFI database BDRFI.

The RFI database BDRFI can be supplied by a system for detecting/locating/inventoring/characterizing interference sources. The system for detecting/locating/inventoring/characterizing interference sources can be capable of collecting data from multiple observations (ground, air, space), by various means such as radars, flight recordings (commercial, freight), boats, preferably located near or in the geographical zone Z. This system could for example be managed by an international organization (e.g. European Organization for Civil Aviation Equipment: EUROCAE, CNS). This system can be capable of analyzing and consolidating data from multiple observations filed on a network via artificial intelligence processing based on data from known interference sources stored in the RFI database and/or information sent back by the calculation and/or monitoring device 10 in order to generate/continuously update the RFI database. This RFI database can be global or limited to a region and is directly exploited by the calculation and/or monitoring device 10.

The interference sources may be stationary and/or emit the interference signal continuously. The interference sources may also be mobile and/or emit the interference signal intermittently and/or consist of different types of modulation and other dynamic characteristics. In this case, the method may comprise a step of acquiring data representative of expected movements of the interference sources and/or data representative of the emission characteristics of the interference sources such as a chronology of emission of the expected interference signal, a modulation of the interference signal and/or other dynamic characteristics. The data representative of expected movements of the interference sources and/or the data representative of the emission characteristics of the interference sources may be acquired by retrieving them from a database where they have been previously deposited, such as the RFI database BDRFI.

The step of acquiring spatial coordinates representative of known positions of interference sources may consist of acquiring spatial coordinates representative of known positions of interference sources potentially harmful to the geographical zone Z and the observation time range concerned. This step makes it possible to limit the memory size of the RFI BDRFI database and to perform calculations only on interference sources considered to be a risk for the safety of the journey.

The calculation and/or monitoring method may further comprise a step of obtaining a desired result in terms of probability. The desired result in terms of probability may correspond to a worst case scenario, a best case scenario, an average case scenario, or a most likely scenario, for example. The desired result in terms of probability may for example be obtained by a user input made using the user interface UI or by retrieving it from a database where it has been previously deposited.

The calculation and/or monitoring method may further comprise a step of obtaining a weather forecast for the geographical area Z and the observation time range. The weather forecast may for example be obtained by retrieving it from a database where it has been previously deposited, such as a weather database.

The calculation and/or monitoring method comprises a step of acquiring data representative of the characteristics of the satellite positioning system. These characteristics include characteristics of the receiver and/or of the installed antenna and/or possibly of one or more additional sensors and/or of one or more anti-interference robustness devices.

The vehicle antenna characteristics may include an antenna pattern giving the gain for each azimuth/elevation. It is recommended that this antenna pattern be representative of the antenna pattern after installation on the vehicle (for example, taking into account masking, attenuations due to the vehicle (e.g. wings) and the ground plane).

The characteristics of the satellite positioning receiver on board the vehicle may include in particular the mathematical model and/or the performance and precision of the receiver, the constellations, services and frequency bands used, the robustness to interference and/or the on-board protection devices, the RF bandwidth, the capacity thresholds (for example, satellite acquisition capacity for a C/No > 36 dB-Hz, tracking capacity for a C/No > 28 dB-Hz), the satellite acquisition and re-acquisition times.

The characteristics of the satellite positioning system on board the vehicle may include in particular the performance and precision of each additional sensor, their participation in the development of the vehicle's PNT and their precision, in particular when certain capabilities of the GNSS receiver are lost (e.g. switching to Inertia or RadioNav mode when the position from the GNSS receiver is imprecise and/or not complete and/or invalid).

The data representative of characteristics of the satellite positioning system can be acquired by retrieving them from a database where they have been previously deposited, such as a database of known receivers BDRC and/or a database of known antennas BDAC. The data representative of characteristics of the receiver and/or the antenna can also be acquired by retrieving them from a memory of the receiver.

The data representative of characteristics of the receiver and/or antenna may correspond to characteristics of a standard receiver and/or a standard antenna. Alternatively, the data representative of characteristics of the receiver and/or antenna may correspond to characteristics of a type of receiver corresponding to the receiver actually installed in the vehicle and/or of a type of antenna corresponding to the antenna actually installed in the vehicle.

The calculation and/or monitoring method comprises a step of calculating the impact of each source of interference on the operation of the satellite positioning system for each spatial and temporal coordinate as a function of the spatial observation coordinate, the temporal observation coordinate corresponding to this spatial observation coordinate, the spatio-temporal coordinates of the satellites at the temporal observation coordinate, the spatio-temporal coordinates representative of the known positions at the temporal observation coordinate of the acquired sources of interference and the data representative of the characteristics of the satellite positioning system.

The step of calculating the impact of each source of interference on the operation of the satellite positioning system may include calculating the distances, elevations, and/or azimuths in order to determine the power received from each source of interference for each spatial and temporal observation coordinate, i.e. either at each position on the path determined for the estimated date on which the vehicle is located at this position, or at any point in the geographical zone Z and over the entire defined observation time range, using propagation models taking into account a loss during the propagation of the interference signal from this source of interference considering, where appropriate, the wavelength of the interference signal and/or the weather forecast for the geographical zone Z and/or terrain masking.

The step of calculating an impact of each interference source on the operation of the satellite positioning system may be performed based on the desired outcome in terms of probability. When the desired outcome in terms of probability corresponds to the worst-case scenario, the step of calculating an impact of each interference source on the operation of the satellite positioning system may be based on the maximum power of the interference signal of the respective interference source, for example. When the desired outcome in terms of probability corresponds to the best-case scenario, the step of calculating an impact of each interference source on the operation of the satellite positioning system may be based on the minimum power of the interference signal of the respective interference source, for example. When the desired outcome in terms of probability corresponds to the average and/or most likely scenario, the step of calculating an impact of each interference source on the operation of the satellite positioning system may be based on the average and/or most likely power of the interference signal of the respective interference source, for example.

• obtention d’une trajectoire planifiée TPR du véhicule, la trajectoire planifiée TPR reliant une position de départ PD à une destination du véhicule et comportant une date de départ du véhicule ou la trajectoire planifiée TPR reliant une position actuelle PA du véhicule à la destination du véhicule et comportant une date actuelle ; et
• détermination des coordonnées spatiales et temporelles d’observation se situant sur la trajectoire planifiée TPR du véhicule à une date estimée à partir de la date de départ du véhicule ou de la date actuelle et d’un temps de trajet estimé pour cette coordonnée spatiale depuis la position de départ du véhicule ou depuis la position actuelle vers cette coordonnée spatiale.

The calculation and/or monitoring method may further include the following steps:

• obtaining a planned trajectory TPR of the vehicle, the planned trajectory TPR connecting a starting position PD to a destination of the vehicle and comprising a departure date of the vehicle or the planned trajectory TPR connecting a current position PA of the vehicle to the destination of the vehicle and comprising a current date; and
• determination of the spatial and temporal coordinates of observation located on the planned trajectory TPR of the vehicle at a date estimated from the departure date of the vehicle or from the current date and an estimated travel time for this spatial coordinate from the departure position of the vehicle or from the current position to this spatial coordinate.

The spatial coordinates defining the starting position PD, the current position PA of the vehicle and/or the destination can for example be acquired by a user input made using the user interface IU. These spatial coordinates can also be acquired by retrieving them from a database where they have been previously deposited. These spatial coordinates can for example be retrieved from a database of the Air Traffic Services BDSCA from a flight plan (FPLN) previously deposited in the latter. The spatial coordinates defining the current position PA of the vehicle can for example be acquired via the receiver.

The planned trajectory TPR may for example correspond to a previously defined or calculated vehicle path. The planned trajectory TPR may for example be obtained by a user input made using the user interface IU or by retrieving it from a database where it has been previously deposited. The planned trajectory TPR may be limited to a flight plan and for example be retrieved from the Air Traffic Services database BDSCA where it is stored as a deposited flight plan or be a precise trajectory linked to the carrier's capabilities from a trajectory calculator or an FMS (English: Flight Management System).

The calculation and/or monitoring method comprises a step of calculating an estimated arrival date for the planned trajectory TPR. The estimated arrival date can be obtained by adding an estimated travel time to the departure date. The estimated travel time can be estimated from previous travel times following the same route or a similar route traveled by other vehicles or from simulations taking into account, among other things, the properties of the vehicle or by retrieving it from the 4D trajectory.

The departure date and estimated arrival date can define the observation time range.

According to one possibility, the departure date can be the date of entry into the geographical zone Z and the arrival date can be the date of exit from the geographical zone.

The calculation and/or monitoring method may comprise a step of determining several positions located on the planned trajectory TPR and, for each of these positions, determining an estimated date on which the vehicle is located at the respective position. The dates and positions located on the planned trajectory may thus each constitute one of the spatial and temporary observation coordinates. The estimated date on which the vehicle is located at the respective position may be estimated from previous travel times following the same route or a similar route traveled by other vehicles or from a calculator taking into account, among other things, the properties of the vehicle.

Positions on the TPR planned trajectory can be spaced equidistantly from each other. The number of positions chosen allows a desired resolution to be defined. The desired resolution can be defined by a user, for example by entering the desired resolution in the UI. The desired resolution can be defined in terms of time period or distance. Two consecutive positions can be spaced 10 seconds apart or 0.2 nautical miles apart for example.

The mentioned method steps may be repeated, preferably repeated at regular intervals. The mentioned method steps may for example be repeated when the vehicle has travelled part of its route. The mentioned method steps may then be repeated taking into account the current position of the vehicle.

• en calculant plusieurs trajectoires possibles TPO du véhicule reliant, soit la position de départ PD à la destination, soit la position actuelle PA à la destination ;
• en déterminant des coordonnées spatiales et temporelles d’observation se situant sur les plusieurs trajectoires possibles TPO du véhicule à une date estimée à partir de la date de départ du véhicule ou de la date actuelle et d’un temps de trajet estimé pour cette coordonnée spatiale d’observation et cette trajectoire possible TPO depuis la position de départ du véhicule ou depuis la position actuelle vers cette coordonnée spatiale d’observation ;
• en calculant les coordonnées spatio-temporelles des satellites du système GNSS pour chaque coordonnée temporelle d’observation de chaque trajectoire possible TPO ;
• en calculant, pour chaque trajectoire possible TPO, l’impact de chaque source d’interférence sur le fonctionnement du système de positionnement par satellites à chacune des coordonnées spatiales et temporelles d’observation en fonction de la coordonnée spatiale d’observation, de la coordonnée temporelle d’observation associée à cette coordonnée spatiale d’observation, des coordonnées spatiales des satellites du système GNSS à la coordonnée temporelle d’observation, des coordonnées spatiales représentatives des positions connues des sources d’interférence acquises à la coordonnée temporelle d’observation, des caractéristiques des sources d’interférence et des données représentatives des caractéristiques du système de positionnement par satellites et/ou de l’antenne du véhicule ;
• en déterminant la trajectoire recommandée TPR parmi les trajectoires possibles TPO en fonction de l’impact de chaque source d’interférence sur le fonctionnement du système de positionnement par satellites à chaque coordonnée spatiale et temporelle d’observation située sur chaque trajectoire possible TPO.

According to one possibility, the planned trajectory TPR of the vehicle is obtained:

• by calculating several possible trajectories TPO of the vehicle connecting either the starting position PD to the destination or the current position PA to the destination;
• by determining spatial and temporal observation coordinates located on the several possible trajectories TPO of the vehicle at an estimated date from the departure date of the vehicle or from the current date and an estimated travel time for this spatial observation coordinate and this possible trajectory TPO from the departure position of the vehicle or from the current position to this spatial observation coordinate;
• by calculating the space-time coordinates of the GNSS system satellites for each observation time coordinate of each possible TPO trajectory;
• by calculating, for each possible trajectory TPO, the impact of each source of interference on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates as a function of the spatial observation coordinate, the temporal observation coordinate associated with this spatial observation coordinate, the spatial coordinates of the satellites of the GNSS system at the temporal observation coordinate, the spatial coordinates representative of the known positions of the sources of interference acquired at the temporal observation coordinate, the characteristics of the sources of interference and the data representative of the characteristics of the satellite positioning system and/or the vehicle antenna;
• by determining the recommended trajectory TPR among the possible trajectories TPO based on the impact of each source of interference on the operation of the satellite positioning system at each spatial and temporal observation coordinate located on each possible trajectory TPO.

This process thus makes it possible to propose and/or classify different TPO trajectories or flight plans to an operator according to the impact of the sources of interference on the operation and in particular on the capacities and performances of the receiver and/or location system on board the respective trajectory in order to be able to select a planned TPR trajectory from the possible TPO trajectories.

When the vehicle is an aircraft, the method allows the preparation of a flight plan (FPLN) taking into consideration the constraints of the presence of interference sources in the geographical zone Z and predictions of losses of receiver capacities during the flight according to the spatial configuration and the aircraft used.

Alternatively, the recommended trajectory as TPR may correspond to the possible trajectory TPO with the lowest impact on the operation of the satellite positioning system. Alternatively, the recommended trajectory as TPR may correspond to the possible trajectory TPO with an impact on the operation of the satellite positioning system below a predefined threshold (e.g. valid PNT, integrates with precision < 0.1nm at 95%) and with minimal vehicle travel time and/or minimal vehicle fuel consumption.

According to a preferred characteristic, for each possible trajectory TPO and/or for the planned trajectory TPR, the calculation of the impact of each source of interference on the operation of the satellite positioning system includes the calculation of the elevations, azimuths and distances of each satellite of the GNSS system at each of the spatial and temporal observation coordinates of the possible trajectory TPO and/or of the planned trajectory TPR.

The method may further comprise a step of acquiring data representative of a category of the vehicle and/or a shape of the vehicle and/or a position of the antenna on the vehicle and/or movement characteristics of the vehicle (attitudes), the impact of each source of interference on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates being calculated as a function of the antenna gain of the vehicle antenna estimated for each spatial and temporal observation coordinate, from the data representative of the category of the vehicle and/or the shape of the vehicle and/or the position of the antenna on the vehicle and/or a 3D orientation (attitudes) of the vehicle at this spatial and temporal observation coordinate on the basis of the data representative of the movement characteristics and dynamic performances of the vehicle.

The data representative of the vehicle category and/or the shape of the vehicle and/or the position of the antenna on the vehicle and/or the movement characteristics of the vehicle may be acquired by retrieving them from a database where they have been previously deposited, such as a vehicle database and/or from a flight simulator and/or trajectory calculator. By “vehicle category” is meant the type of vehicle chosen for example between land vehicle, airplane, helicopter, drone, etc.

The method may further comprise a step of acquiring data representative of a topography of the geographic zone Z, the impact of each source of interference on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates being further calculated as a function of data representative of a topography of the geographic zone Z.

The data representative of the topography of the geographical area Z can be acquired in a database called the DEM (Digital Elevation Model) database BDMNE. The data representative of the topography of the geographical area Z can include data representative of obstacles such as buildings and data from a digital terrain model (DTM). The data representative of the topography make it possible to evaluate masking and signal propagation losses, useful and harmful, such as GNSS signals or interference signals emitted by interference sources. These databases are particularly useful for drone or naval applications, i.e. when the vehicle is a drone or a boat. They are also useful in land and low-altitude flight applications.

The step of calculating the impact of each interference source on the operation of the receiver may include calculating the distances, elevations, and/or azimuth and the power received from each interference source for each spatial and temporal observation coordinate, i.e. either at each position on the path determined for the estimated date on which the vehicle is located at this position, or at any point in the geographical zone Z and over the entire defined observation time range, using precise propagation models also taking into account the loss during propagation of the interference signal from this interference source considering the topography of the terrain, by applying Fresnel equations for example.

When the vehicle is an aircraft, the method may further comprise a step of acquiring data representative of air corridors located in the geographical zone Z, the possible trajectories TPO of the aircraft connecting either the starting position PD to the destination, or the current position PA to the destination, being further calculated from the data representative of the air corridors, the possible trajectories TPO essentially following the air corridors.

As represented in the , the possible trajectories TPO and/or the trajectory recommended as a planned trajectory TPR may comprise a plurality of waypoints PC1 to PC7 constituting different flight plans. These flight plans may coincide with the air corridors. The starting position PD, the current position PA and/or the destination may constitute waypoints PC1 to PC7. In the , waypoints PC1 to PC7 are represented by stars.

As represented in the , the geographical area Z can include a low disruption risk area ZF, a medium disruption risk area ZM and/or a high disruption risk area ZE. The planned trajectory TPR can be determined from four possible trajectories TPO. In the example given by the , the chosen planned trajectory TPR (PC1 – PC2 – PC3 – PC4) from the four possible trajectories TPO can cross the medium disruption risk zone ZM for a short time. Alternatively, the planned trajectory TPR can be chosen so as to remain in the low disruption risk zone ZF (PC1 – PC2 – PC3 – PC5), i.e. without crossing the medium disruption risk zone ZM or the high disruption risk zone ZE by making a more significant detour.

The representative air corridor data can be acquired by retrieving them from a database where they have been previously deposited, such as an air corridor database. The air corridor database can for example be a standard navigation database according to a so-called ARINC 424 format.

The method may further comprise a step of dividing the planned trajectory TPR and/or the different trajectories TPO into a plurality of sections, and a step of determining, for each section, from the impact of each source of interference on the operation of the receiver at each of the spatial and temporal observation coordinates located on the respective section, whether the section is a section with a high disturbance forecast TPE or a section with a low disturbance forecast TPF or, where appropriate, a section with a medium disturbance forecast TPM.

The low TPF disturbance prediction may correspond to a high probability of receiver operation and/or a high probability of GNSS signal integrity, for example. The high TPE disturbance prediction may correspond to a high probability of receiver malfunction and/or a high probability of GNSS PNT loss, for example. The medium TPM disturbance prediction may correspond to a high probability of receiver performance degradation and/or a high probability of GNSS signal integrity loss, for example.

The method may further comprise a step of warning a driver (or pilot) of the vehicle and/or a crew of the vehicle when the current position of the vehicle approaches a section with a high TPE disruption forecast or, where appropriate, a section with a medium TPM disruption forecast. The step of warning the driver may comprise a warning of a loss of integrity, capacity and/or performance of the vehicle receiver. When the vehicle is an aircraft, the warning step may include an alert to warn the pilot as the driver of the aircraft and/or the crew of the aircraft of an imminent exceedance of RNP (English: Required Navigation Performance) and/or an imminent loss of receiver capabilities (for example 2 minutes before the loss of acquisition capability) and/or an imminent switch to a navigation mode without using the satellite positioning system (English: coasting) in order to be able to anticipate and manage the failure of imminent loss of availability of the GNSS PNT with complete peace of mind and improve flight safety. The receiver fault is likely to cause stress among the driver and/or crew. Thus, the possibility of being warned in advance of this fault allows the driver of the vehicle and/or the crew of the vehicle to prepare for this situation and thus reduce the risk of stress among the driver and/or the crew of the vehicle.

The method may further include a monitoring function of checking the operation of the satellite positioning system and/or signal-to-noise ratios, in real time or at regular time intervals, against the predictions. For example, when proper operation of the receiver is detected while the current position of the vehicle is located on a section with high disturbance forecast TPE or, where appropriate, on a section with medium disturbance forecast TPM, or when improper operation of the receiver is detected while the current position of the vehicle is located on a section with low disturbance forecast TPF, the method may comprise a step of generating a message for updating a database of spatial and temporal coordinates for the purpose of updating the known positions of interference sources in the geographical zone Z. When proper operation of the receiver is detected while the current position of the vehicle is located on a section with high disturbance forecast TPE or on a section with medium disturbance forecast TPM, this update message may comprise information indicating a disappearance of at least one interference source and/or an attenuation of the interference signal of at least one interference source at the observation date/time. When a receiver malfunction is detected while the current position of the vehicle is on a section with low TPF disturbance forecast, this update message may include information indicating the appearance of at least one interference source and/or an amplification of the interference signal from at least one interference source at the observation date/time.

Thus, the method monitors and compares in real time the measurements and the risks of disturbance and ensures a loopback to keep the RFI database up to date. The disappearance of a predicted disturbance makes it possible to extrapolate a disappearance or attenuation of one of the known sources of interference. The presence of a disturbance occurring without having been predicted makes it possible to extrapolate an appearance of a new source of interference or an amplification of one of the known sources of interference. This information can then be transmitted so that a monitoring center can update the RFI database after cross-checking the different information received.

The method may further be characterized in that the geographic area Z is divided into a plurality of boxes constituting a grid, the grid preferably comprising a resolution, the spatial and temporal observation coordinates comprising a plurality of positions each located in one of the boxes constituting the grid, preferably located in the center of the box constituting the grid, the geographic area observed for the same instant in time. Preferably, the spatial and temporal observation coordinates all refer to the same instant of observation.

According to one possibility, the plurality of boxes constituting the grid can be arranged in a three-dimensional manner. The grid can for example comprise a bottom layer located at ground level and at least one elevated layer corresponding to a defined altitude such as for example a cruising altitude of an airliner. The defined altitude can for example be defined by the user. The user can enter the desired defined altitude in the user interface UI.

The resolution can be a predefined resolution or a user-defined resolution, for example by entering the desired resolution in the UI.

Thus, the spatial and temporal observation coordinates can either correspond to positions located on a path defined by a planned trajectory TPR and/or a possible trajectory TPO or to positions defining the grid.

The method may further comprise a step of determining the level of signals from the satellites of the GNSS system received for the service(s) used. The step of determining the level of signals from the satellites of the positioning system may be carried out for all the acquired spatial and temporal observation coordinates, i.e. either for any position in the geographical zone Z and/or over the entire observation time range or for all the positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all the dates corresponding to these positions. The method may further comprise a step of displaying the level of signals from the satellites of the GNSS system received for a given position in the geographical zone during the defined observation duration and/or during the tracking of the trajectory. Such a graphical representation is given in FIG. 6A (defined point) and FIG. 11A (during the tracking of a trajectory) as an example.

The method may further comprise a step of determining the antenna gain of the receiver. The determination of the antenna gain may take into account the characteristics of the installed vehicle antenna and/or the position of the vehicle antenna and/or the shape of the vehicle, with a view to possible masking of the antenna by the vehicle for example. This determination step may further take into account the movement characteristics of the vehicle, such as maximum attitudes of the vehicle (e.g. roll, slope), when the vehicle is an aircraft for example. Alternatively or additionally, this determination step may further take into account the estimated attitudes of the vehicle at each position observed during the tracking of the TPR and/or TPO trajectory. For example, when the vehicle is an aircraft and when the aircraft is expected to move in a straight line, such as a level flight, the determination step may further take into account that the aircraft has a horizontal attitude, in which the antenna is located above the fuselage of the aircraft and takes a vertical orientation.

The step of determining the antenna gain can be carried out for all the acquired spatial and temporal observation coordinates, i.e. either for any position in the geographical zone Z and/or over the entire observation time range or for all the positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all the dates corresponding to these positions. The method can further comprise a step of displaying the antenna gain for a given position in the geographical zone during the defined observation duration and/or during the tracking of the trajectory. Such a graphical representation is given in FIG. 6B and FIG. 11B as an example.

The method may further comprise a step of determining the level of signals from the GNSS system satellites after the antenna received. The determination of the level of signals after the antenna received may take into account the characteristics of the installed vehicle antenna and/or the position of the vehicle antenna and/or the shape of the vehicle, with a view to possible masking of the antenna by the vehicle for example. This determination step may further take into account the movement characteristics of the vehicle, such as the maximum attitudes of the vehicle, when the vehicle is an aircraft for example. The step of determining the level of signals after the antenna received from the GNSS system satellites may be carried out for all the acquired observation time coordinates, i.e. either for any position in the geographical zone Z and/or over the entire observation time range or for all the positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all the dates corresponding to these positions. The method may further comprise a step of displaying the level of signals after the antenna of the satellites of the GNSS system received for a given position in the geographical area during the defined observation duration and/or during the tracking of the trajectory. Such a graphical representation is given in FIG. 6C and FIG. 11C as an example.

Similarly, the method may further comprise a step of determining the level of interference signals received for each known interference source. The step of determining the level of interference signals received may be performed for all acquired observation time coordinates, i.e. either for any position in the geographical zone Z and/or over the entire observation time range or for all positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all dates corresponding to these positions. The method may further comprise a step of displaying the level of interference signals received for a known interference source and/or for all interference sources in a particular GNSS frequency band in which a graphical representation of the level of interference signals received is displayed to the user for the defined observation duration and/or during the tracking of the trajectory. Such a graphical representation is given in the (for zone Z) and the (along the trajectory) as an example.

The method may further comprise a step of determining the antenna gain of the receiver with respect to each of the interference sources. The determination of the antenna gain may take into account the characteristics of the installed vehicle antenna and/or the position of the vehicle antenna and/or the shape of the vehicle, with a view to possible masking of the antenna by the vehicle for example. This determination step may further take into account the movement characteristics of the vehicle, such as the maximum attitudes of the vehicle, when the vehicle is an aircraft for example. Alternatively or additionally, this determination step may further take into account the estimated attitudes of the vehicle at each position observed during the tracking of the TPR and/or TPO trajectory. When the aircraft has a horizontal attitude, the fuselage partially masks the interference signals coming from a position below the aircraft.

The step of determining the antenna gain applied to the interferences can be carried out for all the acquired spatial and temporal observation coordinates, i.e. either for any position in the geographical zone Z and/or over the entire observation time range or for all the positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all the dates corresponding to these positions. The method can further comprise a step of displaying the antenna gain and/or antenna diagram for a given position in the geographical zone during the defined observation duration and/or during the monitoring of the trajectory.

The method may further comprise a step of determining the level of the received post-antenna interference signals for each known interference source. The determination of the level of received post-antenna interference signals may take into account the characteristics of the vehicle antenna and/or the position of the vehicle antenna and/or the shape of the vehicle, with a view to possible masking of the antenna by the vehicle for example during the observation period.

This determination step may further take into account the movement characteristics of the vehicle, such as a maximum attitude of the vehicle, when the vehicle is an aircraft for example. The step of determining the level of the post-antenna interference signals may be carried out for all the acquired observation time coordinates, i.e. either for any position in the geographical zone Z and/or over the entire observation time range or for all the positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all the dates corresponding to these positions. The method may further comprise a step of displaying the level of the post-antenna interference signals received for a known interference source in which a graphical representation of the level of post-antenna interference signals received is displayed to the user. Such a graphical representation is given in the (for zone Z) and the (along the trajectory) as an example.

The levels of the received post-antenna interference signals determined also make it possible to establish the destructive zones with respect to the vehicle receiver, for example based on the robustness of the receiver protection diodes.

The method may, following the step of determining the level of signals from the received GNSS system satellites and the step of determining the level of interference signals received for each known interference source, take into account characteristics of the receiver used which may further include: the service of the GNSS system used (for example GNSS L1 C/A, L5C, GALILIEO E1, SBAS), radiofrequency filtering of the receiver by frequency band, saturation/desaturation of an analog-to-digital converter (ADC) of the receiver, behavior and response time of an automatic gain control (AGC) of the receiver, the presence of an anti-interference device integrated into the receiver as well as the properties of such an anti-interference device, a processing gain linked to a spread of the spectrum during correlation by a spread code, a threshold for acquiring satellite signals from the receiver, a threshold for reacquiring satellite signals from the receiver, a threshold for tracking satellite signals from the receiver, a time acquisition and/or reacquisition of satellite signals.

The anti-interference device may be, for example, of the monoammonium phosphate type, of the band-stop filter type, of the anti-carrier wave type or of the adaptive gain type. The properties of the anti-interference device may include a rejection gain of the anti-interference device. Depending on the type of anti-interference device used, the properties of the anti-interference device, the service of the GNSS system used (L1, L2, L5) and the characteristics of the interference received after the antenna (waveform, spectral width, continuous/periodic), some interference will lose effectiveness (partial or total rejection).

The process gain can vary depending on the spectral shape of the interference signal (narrowband, wideband, carrier wave, chirp, etc.), its type (Gaussian, AM/FM modulation, etc.) and the service code of the GNSS system used (C/A, C).

The method may further comprise a step of developing the spectral sum of the interference sources with thermal noise and/or a step of determining a power spectral density for each service and/or frequency band of the GNSS system used or activated.

For example, the represents a table visualizing the residual power -after antenna and receiver processing- of the different interference sources received in the geographical area potentially affecting three services of a GNSS system (L1 C/A, L1C, L5C). The left column of the table represents the level of interference signals received after antenna at any point in the geographical area Z, each row of this column corresponding to a known interference. The three columns on the right of the table each concern a level of the residual interference signal after antenna and after a step of signal filtering, anti-interference processing and correlation of the interference signal with the service of the respective GNSS system for each of the three services. The first column among these three columns concerns the L1 C/A service, the second column among these three columns concerns the L1 C service and the third column, that is to say the last column on the right, among these three columns concerns the L5 C service. For each of the three columns on the right of the table, the first row relates to a first known interference, the second row relates to a second known interference and the third row relates to a third known interference. For example, the box at the top right of the table represents the residual power of the first interference after antenna, after filtering, after anti-interference treatment and after correlation for the L5C service. The bottom row represents the sum of the different residual interference signals for each of the services. For example, the box to the left of the last row represents the sum of the residual powers of the 3 interferences after antenna, after filtering, after anti-interference treatment and after correlation for the L1C/A service.

The method may further comprise a step of calculating the ratio between the level of each signal from the satellites of the GNSS system received after the antenna and the residual sum of the levels of interference signals received after the antenna, after filtering, after anti-interference processing and after correlation from each of the known interference sources. This ratio may be called the signal-to-noise ratio. This step may be calculated for all the acquired spatio-temporal observation coordinates, i.e. either for any point in the geographical zone Z and over the entire observed time range or for all the positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all the dates corresponding to these positions.

The method may further include a display step in which a graphical representation of the signal-to-noise ratio for each satellite and each service is displayed to the user.

The method may, following the step of determining the signal/noise ratio, further comprise a step of determining a prediction of proper operation of the receiver for each of the services of the GNSS system for all the acquired spatio-temporal observation coordinates, i.e. either for any point in the geographical zone Z and over the entire observed time range, or for all the positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all the dates corresponding to these positions.

The method may further comprise a step of displaying the proper functioning of the receiver and its capabilities and performances for each service used in which a graphical representation of the proper functioning of the respective service(s) is displayed to the user. This graphical representation of the proper functioning may comprise multiple layers. As an example, for each of the services used, a first layer among the multiple layers may represent the tracking capability of the receiver, a second layer among the multiple layers may represent the tracking capability of the receiver with integrity, a third layer among the multiple layers may represent the re-acquisition capability, a fourth layer among the multiple layers may represent the satellite signal acquisition capability. Such a graphical representation is given in the as an example for a Z zone. Other layers can be added such as the representation of the tracking capacity in dual frequencies, in dual constellations, the representation of the estimated precision of positions and speeds. The graphical representation of the correct operation can include different cursors, for example an altitude level and a date/time. The graphical representation of the receiver's capacities and performances can be displayed to the user on a map background.

When the stage of good operation is calculated for all positions on the possible trajectories TPO and/or on the planned trajectory TPR and for all dates corresponding to these positions, the display stage may comprise the display of good operation along a 4D trajectory corresponding to a possible trajectory TPO and/or the planned trajectory TPR. The capacities and performances along the 4D trajectory may be displayed to the user on a map background or on a horizontal view or on a vertical view or on a time line view. This display stage makes it possible to present to the user a capacity view and performances of the receiver along and/or near the 4D trajectory. An example of a display of capacities of a receiver for a given service along such a 4D trajectory on a map background is given in the .

The method may further comprise a step of calculating the impact of the present and future operation of the receiver on the on-board positioning system, in particular an estimator of the date or location at which the vehicle will lose its hybridization, switch to inertial mode or navigate using another location sensor (Doppler, radio navigation). In the same way, the capabilities and performance of the location system may be displayed to the user.

When the vehicle is an aircraft, the method may further comprise a step of displaying a representation of the capabilities and/or performances of the satellite positioning system around the 4D trajectory also giving its degree of latitude with respect to a modification of the planned trajectory TPR, or of the flight plan FPLN in the event of a potential diversion (weather, breakdown, etc.).

The method may further include a step of displaying the capabilities and/or performances of the present and future situation of a set or subset of vehicles operating in the monitored geographical zone Z, also enabling information sharing between different actors and assistance with air traffic management (ATM, UTM).

The calculation and/or monitoring device 10 and the calculation and/or monitoring method 10 make it possible to improve the planning of a flight of any airplane or helicopter, to reduce the workload of pilots and/or air traffic management (pilots, ATM) and provide an improvement in air safety.

The calculation and/or monitoring device 10 and the calculation and/or monitoring method allow drone flight preparation with secure trajectory calculation with a PNT solution that is always available.

The calculation and/or monitoring device 10 can be subdivided into two entities:

- an upstream entity that takes into account all the characteristics of the GNSS system, interference sources, topography of the geographic zone Z, obstacles in the geographic zone Z, the 4D trajectory, relief, obstacles and time. The resulting data are generic or universal, and applicable to any user (antenna input).

- a downstream entity which will take into account the characteristics of the carrier, i.e. the vehicle, and its on-board system (antenna, receiver, carrier, positioning system, etc.) and translate this universal data into user data in terms of capacity and performance.

The upstream entity and the downstream entity provide directly operational information via a geographical and temporal representation (present and future) of the impacts of interference sources on operation and in particular on the capacities and performances of the receiver and/or the positioning system adapted to each of the operators.

The calculation and/or monitoring device 10 and the calculation and/or monitoring method make it possible to provide a precise view of the present and future situation in terms of capacity and performance of the receiver and/or the positioning system along and around any trajectory of the vehicle or in the geographical zone Z and corresponding to the system/carrier used.

The calculation and/or monitoring device 10 and the calculation and/or monitoring method also make it possible to alert the crew of an aircraft in advance of any loss of PNT capacity or performance during the flight.

The calculation and/or monitoring device 10 and the calculation and/or monitoring method also make it possible to detect and inform any interference modification in order to allow an update of the RFI database.

The complete system thus allows multiple applications as previously explained and constitutes an asset for improving security, preventive information and decision-making/planning assistance.

Claims (14)

Method for calculating and/or monitoring the operation of a satellite positioning system of a vehicle in a geographical area (Z), the operation of said positioning system including the integrity, capacities and performances of this system, the method comprising the following steps:

• acquisition of spatial and temporal observation coordinates, the spatial observation coordinates being located in the geographic zone (Z);
• acquisition of space-time coordinates of the satellites of a GNSS system for each observation time coordinate;
• acquisition of characteristics and spatio-temporal coordinates representative of known positions of sources of interference of a GNSS system signal, located in or near the geographic zone (Z);
• acquisition of data representative of characteristics of the satellite positioning system;
• calculation of an impact of interference sources on the operation of the satellite positioning system for each service and constellation of the GNSS system and for each spatial and temporal observation coordinate as a function of the spatial observation coordinate, the temporal observation coordinate corresponding to this spatial observation coordinate, the spatio-temporal coordinates of the satellites of the GNSS system at the temporal observation coordinate, the spatio-temporal coordinates representative of the known positions of the interference sources at the temporal observation coordinate and the data representative of characteristics of the satellite positioning system.

Calculation and/or monitoring method according to claim 1, characterized in that it further comprises the following steps:

• obtaining a planned trajectory (TPR) of the vehicle, the planned trajectory (TPR) connecting a starting position (PD) to a destination of the vehicle and comprising a departure date of the vehicle or the planned trajectory (TPR) connecting a current position (PA) of the vehicle to the destination of the vehicle and comprising a current date; and
• determination of the spatial and temporal coordinates of observation located on the planned trajectory (TPR) of the vehicle at a date estimated from the departure date of the vehicle or from the current date and an estimated travel time for this spatial coordinate from the departure position of the vehicle or from the current position to this spatial coordinate.

Calculation and/or monitoring method according to claim 2, characterized in that the planned trajectory (TPR) of the vehicle is obtained:

• by calculating several possible trajectories (TPO) of the vehicle connecting either the starting position (PD) to the destination or the current position (PA) to the destination;
• by determining spatial and temporal observation coordinates located on several possible trajectories (TPO) of the vehicle at an estimated date from the vehicle's departure date or the current date and an estimated travel time for this spatial observation coordinate and this possible trajectory (TPO) from the vehicle's departure position or from the current position to this spatial observation coordinate;
• by acquiring the space-time coordinates of the GNSS system satellites for each observation time coordinate of each possible trajectory (TPO)
• by calculating, for each possible trajectory (TPO), the impact of the interference sources on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates as a function of the spatial observation coordinate, the temporal observation coordinate associated with this spatial observation coordinate, the spatio-temporal coordinates of the satellites of the GNSS system at the temporal observation coordinate, the spatio-temporal coordinates representative of known positions of the interference sources and the data representative of characteristics of the satellite positioning system;
• by determining the planned trajectory (TPR) among the possible trajectories (TPO) based on the impact of interference sources on the operation of the satellite positioning system at each spatial and temporal observation coordinate located on the possible trajectory (TPO).

Calculation and/or monitoring method according to claim 3, characterized in that, for each possible trajectory (TPO) and/or for the planned trajectory (TPR) or for any point in the geographic zone (Z), the calculation of the impact of the interference sources on the operation of the satellite positioning system includes the calculation of the distances, elevations and azimuths of each interference and of each satellite of the GNSS system at each of the spatial and temporal observation coordinates of the possible trajectory (TPO) and/or of the planned trajectory (TPR) and/or of the geographic zone (Z). Calculation and/or monitoring method according to any one of claims 1 to 4, characterized in that it further comprises the following step:

• acquisition of data representative of a vehicle category and/or a vehicle shape and/or an antenna position on the vehicle and/or vehicle motion characteristics; and

in that said impact on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates is calculated as a function of an antenna gain of the vehicle antenna estimated for each spatial and temporal observation coordinate, from data representative of the vehicle category and/or the shape of the vehicle and/or the position of the antenna on the vehicle and/or an orientation of the vehicle at this spatial and temporal observation coordinate estimated on the basis of data representative of the movement characteristics. Calculation and/or monitoring method according to any one of claims 1 to 5, characterized in that it further comprises the following step:

• acquisition of data representative of a topography and obstacles of the geographic zone (Z); and

in that said impact on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates is further calculated based on data representative of a topography of the geographic area (Z). Calculation and/or monitoring method according to any one of claims 1 to 6 taken in combination with claim 3, the vehicle being an aircraft, the method being characterized by the following step:

• acquisition of data representative of air corridors located in the geographic zone (Z);

and in that the possible trajectories (TPO) of the aircraft connecting either the starting position (PD) to the destination or the current position (PA) to the destination are further calculated from data representative of the air corridors, the possible trajectories (TPO) essentially following the air corridors. Calculation and/or monitoring method according to any one of claims 1 to 7, characterized in that the acquisition of spatial coordinates representative of known positions of interference sources is repeated at regular intervals. Calculation and/or monitoring method according to any one of claims 1 to 8 taken in combination with claim 2, characterized in that it further comprises the following step:
- division of the planned trajectory (TPR) into a plurality of sections determined according to the impact of the interference sources on the operation of the satellite positioning system at each of the spatial and temporal observation coordinates located on the respective section, in particular if the section is a section with a high disturbance forecast (TPE) or a section with a low disturbance forecast (TPF). Calculation and/or monitoring method according to claim 9, characterized in that it further comprises the following step:

• warning a driver and/or vehicle crew when the current vehicle position is approaching a section with high disruption prediction (TPE), and/or in the event of loss of capacity and/or performance degradation.

Calculation and/or monitoring method according to any one of claims 9 or 10, characterized in that it further comprises the following steps:

• checking the proper functioning, performance and capabilities of the vehicle positioning system at regular time intervals against the predictions;
• if the deviation from the predictions is greater than a threshold, generation of a message updating a database of spatial coordinates representative of the known positions of interference sources in the geographic area (Z).

Calculation and/or monitoring method according to any one of claims 1 to 11, characterized in that the geographical area (Z) is divided into a plurality of boxes constituting a grid, the grid preferably comprising a predefined resolution, the spatial and temporal observation coordinates comprising a plurality of positions each located in one of the boxes constituting the grid, preferably located in the center of the box constituting the grid, the geographical area observed for the same instant in time, the spatial and temporal observation coordinates all referring to the same instant of observation. Computer program product comprising software instructions which, when executed by a computer, implement the calculation and/or monitoring method according to any one of the preceding claims. Device for calculating and/or monitoring the operation of a satellite positioning system of a vehicle in a geographical zone (Z), comprising technical means adapted to implement the calculation and/or monitoring method according to any one of claims 1 to 12.