Method of ephemeris support for the control process of low-orbital navigation system spacecraft

Abstract

FIELD: navigation systems.SUBSTANCE: invention relates to navigation systems (NS) and can be used for ephemeris control of spacecraf (SC). The essence of the method consists in the fact that equipment for generating a message comprising the parameters of the spacecraft's orbit and synchronizing the onboard time scale with the time scale of the spacecraft of a low-orbit NS is installed on a specialized spacecraft, specialized messages are generated by means of the equipment with the help of at least four spacecraft located in the same orbital plane, which are fed to the spacecraft of the low-orbit NS; the Doppler shift of the signal frequency of the specialized messages is measured, the orbital parameters of the spacecraft of the low-orbit NS are determined based on the values of the Doppler shift and the orbital parameters of the specialized spacecraft, ephemeris information is obtained and navigation messages are generated, transmitted to consumers of navigation information.EFFECT: high accuracy of spacecraft ephemerides, as well as reduced requirements for the stability of the reference frequency generator.1 cl, 2 dwg

Description

[0001] The invention relates to space navigation and can be used to calculate the ephemerides of spacecraft (SC) of a low-orbit navigation system (LON).

[0002] The feasibility of using navigational determination methods and hardware developed during the creation of a medium-orbit global navigation satellite system (GNSS) leads to the advisability of using a pseudo-rangefinding navigation method implemented during the construction of second-generation GNSS. This method provides for the continuous maintenance of a unified system time scale on all satellites of the navigation system and the provision of high-precision ephemeris information. With the pseudo-rangefinding navigation method, navigational determinations require simultaneous observation by a ground-based user of at least four navigation satellites in the celestial sphere. To achieve this, the construction of a global GNSS requires placing approximately 300 satellites in orbit as part of the GNSS. In this case, small satellites can be used as GNSS satellites, and the GNSS can be considered a multi-satellite orbital group (MOG).

[0003] A known method of ephemeris support for the GNSS spacecraft control process is whereby the orbital parameters and ephemeris of each spacecraft are determined using an extensive network of ground-based control and measuring stations [1-GLONASS. Principles of Design and Operation. / Ed. by A.I. Petrov, V.N. Kharisov. - Moscow: Radio Engineering, 2005, pp. 16-17]. Ephemeris support means determining and forecasting the motion parameters of all GNSS spacecraft for the purpose of subsequent transmission of this information by the spacecraft to consumers in a navigation message [1, p. 15]. The motion parameters of GNSS spacecraft transmitted in a navigation message are called ephemeris information [1, p. 14].

[0004] The network of ground stations does not ensure continuous interaction between the GNSS spacecraft and the GNSS ground control complex, therefore the updating (refining) of the ephemeris information onboard the GNSS spacecraft is performed periodically. Thus, the GLONASS GNSS uses an ephemeris support technology, in which the ephemeris information is updated once or twice a day, and the duration of the predicted flight interval is about one day [1, p. 303]. The initial information for calculating the ephemeris information is the values ​​​​of the current navigation parameters of the spacecraft's motion, measured by ground control stations and transmitted to the GNSS control coordination and computing center, which determines the orbits and calculates the ephemeris information. Moreover, to achieve high-precision calculations of the ephemeris information, 10 to 12 measurement sessions are carried out daily for each GNSS spacecraft [1, p. 302].

[0005] The disadvantages of the described method are:

[0006] - a large number of daily measurements of current navigation parameters performed by ground-based control measuring stations and necessary for calculating the ephemeris information of the spacecraft of the navigation group with the required accuracy, especially when using this method for calculating the ephemeris of a large low-orbit group;

[0007] - the occurrence of an error in the ephemeris of the spacecraft navigation system, arising as a result of the difference between the predicted physical state of the space environment and the actual state in the interval of prediction of the spacecraft movement and calculation of the ephemeris, due to the fact that the ephemeris on board the spacecraft, as a rule, is once a day, and the duration of the ephemeris prediction interval is one day [1, p. 303];

[0008] - high requirements for the stability of the on-board frequency standard of GNSS spacecraft due to the fact that the duration of the predicted flight interval and the calculation of ephemeris information is, as a rule, one day.

[0009] The existing ground infrastructure is not designed to provide ephemeris information to 300 spacecraft, therefore the described method cannot be implemented to ensure the operation of the full complement of the NNS.

[0010] A known method of ephemeris provision allows to increase the accuracy of ephemerides, in which onboard inter-satellite measurement equipment (IAMI) is used to measure the parameters of relative motion of GNSS spacecraft and determine (refinement) the parameters of their orbits [1, pp. 448-458]. IAMI is used to solve the following problems: measuring the parameters of relative motion of GNSS spacecraft; transmitting ephemerides and frequency-time corrections in the GNSS spacecraft network. Measurements of the parameters of relative motion are carried out by measuring the pseudo-ranges and pseudo-velocities of movement of some GNSS spacecraft relative to others. The method allows to reduce the error of ephemerides due to frequent refinement of orbit parameters using IAMI and subsequent calculation of ephemerides by the onboard control complex of each GNSS spacecraft.

[0011] The method enables determination of the relative position parameters of spacecraft in a GNSS orbital constellation. However, for high-precision navigation of navigation information consumers, it is necessary to determine the spacecraft orbital parameters in a coordinate system associated with the rotating Earth, in other words, to tie the GNSS orbital constellation parameters to the coordinate system of the navigation information consumer. This tie is achieved by determining the orbit of one or more spacecraft using ground-based reference measurement stations. After transmitting ephemeris information calculated from measurements by ground stations to a given spacecraft, the method enables the orbital parameters and ephemerides of all spacecraft in the GNSS orbital constellation to be refined relative to that spacecraft. Such a spacecraft can essentially be considered a reference spacecraft, relative to which the orbits of the GNSS spacecraft are directly refined.To ensure continuous maintenance of high accuracy of GNSS spacecraft ephemerides relative to Earth-bound coordinate systems, it is necessary to maintain high accuracy of the ephemerides of one or more reference spacecraft, which dictates the need to conduct measurements of the current navigation parameters of their orbits using ground-based control measurement stations and, after the measurements, the following technological operations: transmission of measurements to the processing center; determination of the orbits of the reference spacecraft and calculation of ephemeris information for them; transmission of work programs to ground-based control measurement stations; conducting communication sessions with the reference spacecraft to load work programs.

[0012] The disadvantages of this method are:

[0013] - significant energy consumption of the navigation system spacecraft when conducting inter-satellite measurements using the BAMI due to the significant distance between the GNSS spacecraft and the specific operating modes of the BAMI when conducting inter-satellite measurements;

[0014] - the need to measure current navigation parameters of the spacecraft movement of the navigation system using an extensive network of ground-based control measuring stations;

[0015] - the need to carry out labor-intensive technological operations to determine the orbits of standard spacecraft and calculate ephemeris information for them; transfer of work programs to ground control measuring stations, loading of work programs;

[0016] - high requirements for the stability of the on-board frequency standard of GNSS spacecraft due to the significant duration of the ephemeris information calculation interval.

[0017] The need for measurements by ground stations leads to resource expenditure, firstly, for the ground complex itself, for measuring current navigation parameters, calculating ephemerides, and transmitting them to the spacecraft, and secondly, for maintaining the extensive network of ground complex measurement stations in working order. Since measurement stations are expensive technical systems, resource expenditure is significant. Furthermore, not all satellites in a GNSS orbital constellation can be simultaneously visible from a single reference satellite. Thus, when viewed from any satellite in a GNSS orbital constellation, some of them are obscured by the Earth, so it is impossible to calculate the ephemerides of all satellites in the GNSS orbital constellation directly relative to a single reference satellite. This leads to:

[0018] - or the need to refine the ephemerides of those GNSS spacecraft that are invisible to the reference spacecraft, by means of inter-satellite measurements relative to other spacecraft, the ephemerides of which are calculated directly relative to the reference spacecraft, which leads to the accumulation of errors in the calculation of ephemerides during inter-satellite measurements;

[0019] - or the need to use several standard spacecraft, which leads to an increase in the resource costs of the GNSS ground control complex for calculating the ephemeris of several standard spacecraft.

[0020] Using this method for calculating the ephemeris of the NNS may lead to a significant increase in the error in calculating the ephemeris due to the accumulation of errors in inter-satellite measurements due to the fact that the NNS is a multi-satellite orbital grouping and the refinement of the ephemeris of any NNS spacecraft may require the need to carry out a number of stages of refining the ephemeris of other MOG spacecraft.

[0021] A method for providing ephemeris support for the process of controlling spacecraft of a navigation system is known [2 - patent RU 2390730, Method for providing ephemeris support for the process of controlling spacecraft of a global navigation satellite system. / Strelnikov S.V., IPC G01C 21 / 24, published 05 / 27 / 2010, bulletin No. 15].

[0022] The method described in patent 2390730 involves launching a low-orbit satellite into a forward or reverse-inclination orbit. The satellite is equipped with equipment for synchronizing its onboard time scale with the navigation system's system time scale, equipment for measuring current navigation parameters based on terrestrial television signals from stationary ground-based television and radio stations and determining the low-orbit satellite's orbital parameters, and onboard inter-satellite measurement equipment. During orbital flight, the low-orbit spacecraft's onboard time scale is synchronized with the navigation system's system time scale, and the low-orbit satellite's orbital parameters are determined based on television and radio station signals.Onboard navigation system satellites conduct intersatellite measurements of the navigation system's spacecraft motion parameters relative to a low-orbit spacecraft. A navigation message containing its orbital parameters, measured using television signals, is generated onboard the low-orbit spacecraft, and transmitted and received by the navigation system's spacecraft. Onboard control systems for the navigation system's spacecraft determine their orbital parameters and ephemerides based on intersatellite measurements and the low-orbit spacecraft's orbital parameters.

[0023] The method described in patent 2390730 determines the orbit of a low-orbit satellite by measuring the signal parameters of certain ground-based television and radio stations, which are essentially ground-based radio beacons. The disadvantages of this method when used to calculate the ephemerides of a low-orbit satellite include:

[0024] - the need to install inter-satellite measurement equipment on the LEO satellites, which leads to an increase in the cost, weight and dimensions of the satellites, taking into account that LEO satellites are small-sized products; due to the fact that the distance between the low-orbit satellites and the GNSS satellites is at least 19,000 km, the inter-satellite measurement equipment is expensive and has significant dimensions when compared with the volume of the small-sized satellites;

[0025] - the need to conduct inter-satellite measurements between the navigation system spacecraft and low-orbit spacecraft to determine the orbital parameters of the navigation system spacecraft, which leads to the expenditure of energy resources of the navigation system spacecraft for conducting inter-satellite measurements.

[0026] A known method for providing ephemeris support for the control process of a spacecraft of a navigation system [3 - patent RU 2477836, Method for providing ephemeris support for the control process of spacecraft of the global navigation satellite system, Strelnikov S.V., IPC G01C 21 / 24, published 03 / 20 / 2013, Bulletin No. 8] taken as a prototype. In the method according to patent 2477836, the on-board time scale of each spacecraft of the navigation system is synchronized with the system time scale. A special low-orbit spacecraft (SLOS) is launched into an orbit with direct or inverse inclination, on which equipment is placed for synchronizing the on-board time scale with the system time scale of the navigation satellite system, equipment for measuring current navigation parameters of movement based on signals from ground-based radio beacons and determining the orbital parameters of the special low-orbit spacecraft based on them.During orbital flight, the satellite's onboard time scale is synchronized with the navigation satellite system's system time scale, the satellite's orbital parameters are determined using ground-based radio beacon signals, and the satellite's navigation equipment is installed. This equipment receives navigation messages from the satellite's navigation satellite system and measures the Doppler frequency shift of the navigation message signal. The satellite's orbital parameters are then calculated using the measured Doppler frequency shift and the satellite's orbital parameters. The calculated orbital parameters are transmitted and received by the satellite's navigation system. Ephemerides are calculated in the satellite's onboard control systems.

[0027] The significant disadvantages of the method when applied for ephemeris support of the control process of a multi-satellite NNS are:

[0028] 1) due to the fact that the NNG is a mobile group, there are no guarantees that during orbital motion for all the spacecraft of the multi-satellite NNS with the required periodicity necessary for refining and updating the ephemerides of the NNG spacecraft, joint radio visibility zones of the NNS and the multi-satellite satellite will arise even if several multi-satellite satellites are used;

[0029] 2) the method does not provide for requirements for the parameters of the satellite orbit, as well as requirements for the orbital structure of a possible satellite orbital grouping, the use of which will ensure the required frequency of occurrence of joint radio visibility zones of the NNS and satellites;

[0030] 3) the possibility of signal collisions occurring when the onboard equipment of the satellite system receives navigation messages from the satellite navigation system, since a large number of satellites of a large number of satellites will be within the radio visibility zone of each satellite system; due to the possible collision of radio signals of navigation messages received from the satellite navigation system, the correct processing of navigation messages by the onboard equipment of the satellite system is a complex technical task;

[0031] 4) taking into account the orientation of the antenna pattern of the navigation satellite system (NSS) intended for emitting navigation messages towards ground-based users, for receiving navigation messages by the onboard equipment of the NSS, the orbital altitude of the NSS should be less than the orbital altitude of the NSS; the orbital altitude of the NSS should be at altitudes at which, in order to maintain the orbital parameters, it is necessary to carry out orbital maneuvers to eliminate the negative influence of the atmosphere, to maintain the orbital altitude of a given duration of the active existence of the NSS; or an additional antenna should be installed on the NSS, provided that the NSS is placed in an orbit located above the orbit of the NSS.

[0032] The technical problem that the claimed invention is aimed at solving is ensuring high accuracy of the ephemeris of the spacecraft of a multi-satellite navigation system by frequently updating the orbital parameters of the spacecraft of the navigation system without measuring the current navigation parameters of the spacecraft of the navigation system using expensive ground-based measuring stations.

[0033] To solve the specified technical problem, a method is proposed for providing ephemeris support for the control process of a low-orbit navigation system spacecraft, in which the on-board time scale of the low-orbit navigation system is synchronized with the system time scale of the low-orbit navigation system, the orbital parameters of the low-orbit navigation system are determined using signals from ground-based radio beacons, and high accuracy of the orbital parameters of the low-orbit navigation system is continuously maintained by frequently receiving and processing signals from ground-based radio beacons.

[0034] According to the invention, at least four satellites are launched into orbit, they are placed in one orbital plane, specialized messages are generated during flight by the on-board means of each satellite, specialized messages are emitted containing the parameters of the satellite movement and units of the on-board time scale in the direction of the flight trajectories of the NNS spacecraft.

[0035] The onboard equipment of the navigation satellite receives specialized messages, measures the Doppler frequency shift of the specialized message signal, synchronizes the onboard time scale with the satellite's time scale, and calculates the orbital parameters of the navigation satellite based on the measured Doppler frequency shift of the specialized message signal and the satellite's orbital parameters. Ephemeris information is then calculated from the orbital parameters of the navigation satellite and used to generate navigation messages, which are transmitted to navigation information consumers for navigational purposes.

[0036] The primary technical result achieved by the claimed invention is the continuous maintenance of high-precision ephemerides of the NSS spacecraft by frequently updating their orbital parameters. An additional technical result achieved by the claimed invention is the reduction of stability requirements for the NSS spacecraft's reference frequency generator by enabling frequent updating of the onboard time scale.

[0037] Fig. 1 shows a block diagram of device 1, intended for installation on board a special low-orbit spacecraft. Fig. 2 shows a block diagram of device 10, intended for installation on board a low-orbit navigation system spacecraft.

[0038] Numerical assessments of the feasibility of implementing the proposed method show that if the altitude of the near-circular orbit of the NNS satellite is 500 km, and the NS satellites are at an altitude of 1000 km, the radius of the NS satellite's radio visibility zone, within which the NS satellite observes the NNS satellite, will be no less than 5900 km. Then, if four NS satellites are placed in a single plane, these radio visibility zones of two adjacent NS satellites will overlap, and this overlap will create a band of overlapping radio visibility zones. When four NS satellites are placed in a single plane, the width of the overlap zone will be 2280 km, and the duration of the flight through it for the NNS satellite will be no less than 280 seconds. When five NS satellites are placed in a single plane, the width of the overlap zone will be 7300 km, and the duration of the flight through the overlap zone will be no less than 920 seconds.This means that a navigation satellite flying through the radio visibility zone can perform two operations necessary for updating ephemeris information: receiving specialized messages from the satellite; and synchronizing (updating) the navigation satellite's onboard time scale with the satellite's time scale. The minimum flight duration of a navigation satellite in the radio visibility zone of a satellite occurs when the planes of the navigation satellite and the satellite are perpendicular. Obviously, the minimum duration will be 280 seconds when four satellites are deployed in an orbital plane, and 920 seconds when five satellites are deployed in a single orbital plane.

[0039] The Doppler shift in the frequency of the ground radio beacon signal, measured onboard the satellite, is the current navigation parameter used in calculating the satellite orbit parameters. The satellite orbit determination can be implemented using the method described in the patent [4 - patent RU 2367910, Method for constructing an orbital-based functional supplement to a global navigation satellite system. / Strelnikov S.V., Mironyuk A.I., IPC G01C 21 / 24, published 20.09.2009, Bulletin No. 26].

[0040] The Doppler frequency shift of the radio signal of a specialized message, measured onboard the NSS spacecraft, is essentially a current navigation parameter used in calculating the NSS spacecraft ephemeris. The determination of the NSS spacecraft orbit can be implemented using the method described in the patent [5 - patent RU 2520714. Method for determining the orbit of a spacecraft. / Strelnikov S.V., Bubnov V.I., Rodionova G.G., IPC B64G 3 / 00, published 27.06.2014, bulletin No. 18].

[0041] Essential features characterizing the invention:

[0042] 1. Launch of at least four satellites into one orbital plane.

[0043] 2. Formation and emission in the direction of flight trajectories of low-orbit navigation system spacecraft for specialized communications.

[0044] 3. Placement in the onboard equipment of the NNS spacecraft of means for receiving a specialized message and equipment for measuring the Doppler shift of the frequency signal of the specialized message and determining the orbit of the NNS spacecraft.

[0045] 4. Performing the following set of sequential actions to calculate the ephemeris of the NNS spacecraft:

[0046] - synchronization of the onboard time scale of the GNSS with the system time scale of the NNS by using standard ground control stations used in GNSS for synchronization of the onboard time scales of navigation spacecraft with the system time scale of the navigation system;

[0047] - determination of the orbital parameters of a low-orbit spacecraft based on current navigation parameters measured by signals from ground-based radio beacons;

[0048] - formation and emission in the direction of the flight trajectories of the low-orbit navigation system of specialized communications spacecraft;

[0049] - reception of a specialized message by the onboard equipment of the NNS spacecraft, measurement of the Doppler shift in the frequency of the specialized message signal;

[0050] - synchronization of the onboard time scale of the NNS spacecraft with the time scale of the SNKA during the flight of the NNS spacecraft in the radio visibility zone of the SNKA;

[0051] - determination of the orbit of the NNS spacecraft based on the parameters of the SNKA orbit and the values ​​of the Doppler shift of the specialized message signal;

[0052] - calculation of ephemeris information onboard the NNS spacecraft, generation of navigation messages for navigation definitions of consumers. Properties of the proposed method:

[0053] 1) If several ground-based radio beacons are deployed across the country and the satellite is launched into a near-polar orbit, each satellite can receive signals from ground-based radio beacons and refine its orbit at each orbit; thereby continuously maintaining high-precision parameters; a minimum number of ground-based radio beacons will be required when deployed in the polar regions of the country; terrestrial television stations equipped with a highly stable reference frequency generator can be used as radio beacons;

[0054] 2) when flying near the orbital plane of the satellite, each satellite of the navigation system has the ability to receive navigation messages from the satellite;

[0055] 3) The low-orbit navigation system satellite crosses the orbital plane of the low-orbit navigation system twice during one orbital revolution; therefore, the on-board time scale and ephemeris of each navigation satellite can be refined twice per orbit, ensuring their high accuracy on a continuous basis;

[0056] 4) Since the orbital parameters of the low-orbit navigation system are constantly maintained with high accuracy, the ephemerides of each low-orbit navigation system satellite can be refined twice per orbit; therefore, the requirements for the stability of the frequency standard of the low-orbit navigation system satellites can be reduced compared to the requirements for the stability of the frequency of the GLONASS satellites;

[0057] 5) when receiving navigation messages from the satellite, necessary for the implementation of the claimed method, the energy consumption of the satellite is low compared to the use of inter-satellite measurement equipment, due to the fact that the distance between the satellite and the satellite in the claimed method is significantly less than between the satellite and the GNSS in the method in which on-board inter-satellite measurement equipment (IAME) is used to measure the parameters of the mutual motion of the GNSS satellite and determine the parameters of their orbits [1, pp. 448-458].

[0058] The advantages of the claimed invention are:

[0059] - high-precision determination of orbits and calculation of ephemeris of any spacecraft from the NNS without the use of ground-based measuring instruments and navigation messages from medium-orbit GNSS;

[0060] - continuous maintenance of high accuracy of the ephemeris of any satellite from the NNS by updating the ephemeris twice at the interval of one orbit during a flight in the radio visibility zone of the satellite;

[0061] - the ability to determine the orbit of a satellite using signals from ground-based radio beacons and continuously maintain high accuracy of the orbital parameters of the satellite without requiring significant expenditure of ground-based resources;

[0062] - the possibility of coordinating the time scale of the SNKA and any NNS spacecraft with the system time scale of the low-orbit navigation system twice during the interval of one orbit of the NNS spacecraft, and the possibility of continuously maintaining high accuracy of the on-board time scale of the NNS spacecraft relative to the system time scale of the low-orbit navigation system;

[0063] - reducing the level of requirements for the stability of the frequency standard of the low-orbit satellites compared to the level of requirements for the standard of the GNSS satellites in medium orbits due to the possibility of refining the time scale twice during the interval of one revolution of the low-orbit satellite during its flight in the radio visibility zone of the medium-orbit satellites;

[0064] - relatively low resource costs during the operation of the NNS spacecraft due to the ability to perform the necessary technological operations for calculating and updating ephemeris information on board the NNS spacecraft in the automatic mode of operation of ground and onboard facilities provided for by the declared method.

[0065] The block diagram of the devices intended for implementing the proposed method is shown in Figures 1 and 2 (Fig. 1, Fig. 2).

[0066] Device 1 in Fig. 1 contains an antenna (ANTsZ) 2 directed toward the center of the Earth, transmitting and receiving equipment (TRE) 3, an on-board digital computer (ODC) 4, equipment for synchronizing the on-board time scale with the system time scale of the global navigation satellite system (SNBShV) 5, equipment for measuring current navigation parameters of movement using radio beacon signals and determining the orbital parameters of the SNKA using them (IZOR) 6, equipment for generating a specialized navigation message (FSNS) 7, an antenna 8 directed into outer space in the direction of the NNS spacecraft (ANKP), equipment for synchronizing the on-board time scale of the SNKA with the time scale of the NNS spacecraft (SShV) 9.

[0067] The device 10 in Fig. 2 contains an antenna (ANKA) 11, intended for information exchange with the SNKA, a transmitting and receiving equipment (TRE) 12, an on-board digital computer (ODC) 13, equipment for synchronizing the on-board time scale of the NNS spacecraft with the SNKA time scale (SBSHV) 14, equipment for measuring the Doppler frequency shift of the received signal of a specialized navigation message and determining the orbital parameters of the NNS spacecraft based on the values ​​of the message radio signal parameters and the values ​​of the SNKA orbital parameters (IZOR) 15, equipment for generating a navigation message for navigation definitions of consumers (FNSP) 16, a transmitting antenna 17, oriented in the direction of the navigation information consumers (ANP).

[0068] In this case, in device 1 in Fig. 1 the first input of the transmitting and receiving equipment 3 is connected to the output of the antenna 2, and the second input of the PPA 3 is connected to the first output of the on-board computer 4, the first output of the transmitting and receiving equipment 3 is connected to the input of the antenna 2, the second output of the transmitting and receiving equipment 3 is connected to the first input of the on-board computer 4, the third output of the PPA 3 is connected to the input of the antenna 8, the third input of the PPA 3 is connected to the output of the antenna 8, the second input of the on-board computer 4 is connected to the output of the SBSHV 5, the third input of the on-board computer 4 is connected to the output of the ISOR 6, the fourth input of the on-board computer 4 is connected to the output of the FSNS 7, the fifth input of the on-board computer 4 is connected to the output of the SBSHV 9, the second output of the on-board computer 4 is connected to the input of the SBSHV 5, the third output of the on-board computer 4 is connected to the input of the ISOR 6, the fourth output of the on-board computer 4 is connected to the input of the FSNS 7, The fifth output of the BCVM 4 is connected to the input of the SSHV 9.

[0069] In the device 10 in Fig. 2, the first input of the transmitting and receiving equipment 12 is connected to the output of the antenna 11, the second input of the TPE 12 is connected to the first output of the on-board computer 13, the first output of the TPE 12 is connected to the input of the antenna 11, the second output of the TPE 12 is connected to the first input of the on-board computer 13, the third output of the TPE 12 is connected to the input of the transmitting antenna 17, the second input of the on-board computer 13 is connected to the output of the SBSHV 14, the third input of the on-board computer 13 is connected to the output of the ISOR 15, the fourth input of the on-board computer 13 is connected to the output of the FNSP 16, the second output of the on-board computer 13 is connected to the input of the SBSHV 14, the third output of the on-board computer 13 is connected to the input of the ISOR 15, the fourth output of the on-board computer 13 is connected to the input of the FNSP 16.

[0070] The devices of Fig. 1 and 2 operate as follows.

[0071] Device 1 in Fig. 1, located on the SNKA, when flying in the radio visibility zone of a ground radio beacon, receives a radio signal emitted by the radio beacon, which is fed to antenna 2, then to PPA 3 and then to the on-board computer 4. The on-board computer 4 selects the parameters of the radio beacon radio signal, which are fed to the equipment ISOR 6, in which the Doppler shift of the radio beacon radio signal frequency is measured, the orbital parameters of the SNKA are determined and the obtained orbital parameters are transmitted to the on-board computer 4. In this case, antenna 2 receives the radio beacon signal, which is fed from the output of antenna 2 to the first input of PPA 3, then from the second output of PPA 3 to the first input of the on-board computer 4, then from the third output of the on-board computer 4 to the input of ISOR 6. The orbital parameters calculated in ISOR 6 are fed from the output of ISOR 6 to the third input of the on-board computer 4.

[0072] When located within the radio visibility zone of the ground control station, designed to synchronize the system time scale of the navigation system and the on-board time scale of the spacecraft, the on-board time scale of the SNKA and the system time scale of the navigation system are synchronized by using antenna 2, PPA 3, BCVM 4 and SBShV 5.

[0073] The orbit parameters required to calculate the onboard time scale corrections to the navigation system's system time scale are sent from the second output of the onboard digital computer 4 to the input of the satellite-based time scale controller 5, which generates a radio signal containing the onboard time scale values ​​and the satellite's orbital parameters. The generated radio signal is sent from the output of the satellite-based time scale controller 5 to the second input of the onboard digital computer 4, then from the first output of the onboard digital computer 4 to the second input of the satellite-based time scale controller 3, then from the first output of the satellite-based time scale controller 3 to the input of antenna 2, which transmits the radio signal toward the ground control station that performs synchronization. Antenna 2 receives the signal containing the onboard time scale correction values ​​calculated and transmitted by the ground control station. The use of these corrections ensures the synchronization of the satellite's onboard time scale with the NNS's system time scale.The signals with corrections are sent from the output of antenna 2 to the first input of PPA 3, then from the second output of PPA 3 to the first input of the on-board digital computer 4, and then from the second output of the on-board digital computer 4 to the input of the SBSHV 5, which makes corrections to the on-board time scale to ensure its synchronization with the system time scale of the NNS.

[0074] FSNS 7 generates a specialized navigation message, including the parameters of the SNKA orbit and the values ​​of the SNKA time scale, synchronized with the system time scale of the navigation system. The parameters of the SNKA orbit are received by FSNS 7 from the fourth output of the onboard computer 4, and the values ​​of the time scale are received from the output of the SBSHV 5, first to the second input of the onboard computer 4, and then from the fourth output of the onboard computer 4 to the input of FSNS 7. The generated specialized navigation message from FSNS 7 is sent to the fourth input of the onboard computer 4, then from the first output of the onboard computer 4 to the second input of the PPA 3, then from the third output of the PPA 3 to the antenna 8, which transmits the specialized navigation message to the region of space in which the NNS satellites are located.

[0075] The NNS spacecraft receives a specialized navigation message emitted by the SNKA, which is sent to antenna 11, then to PPA 12 and then to the on-board computer 13. The on-board computer 13 selects the parameters of the message radio signal and the parameters of the SNKA orbit, which are sent to the ISOR 15 equipment, which measures the Doppler shift of the frequency of the specialized message radio signal, determines the orbital parameters of the NNS spacecraft and transmits the obtained orbital parameters to the on-board computer 13. In this case, the received radio signals of the navigation message from the output of antenna 11 are sent to the first input of PPA 12, then from the second output of PPA 12 to the first input of the on-board computer 13, then from the third output of the on-board computer 13 to the input of ISOR 15. The orbital parameters calculated in ISOR 15 are sent to the third input of the on-board computer 13.

[0076] Synchronization of the on-board time scale of the NNS spacecraft with the system time scale of the navigation system is carried out by using antenna 11, PPA 12, on-board digital computer 13 and SBShV 14. In this case, signals corresponding to the time values ​​of the on-board time scale of the NNS spacecraft, necessary for calculating the corrections of the on-board time scale of the NNS spacecraft to the system time scale of the NNS, are received from the output of SBShV 14 to the second input of the on-board digital computer 13, which forms a radio signal for synchronizing the time of the NNS spacecraft, containing the values ​​of the on-board time scale and the orbital parameters of the NNS spacecraft, which is then received from the first output of the on-board digital computer 13 to the second input of the PPA 12, then from the first output of the device 12 to the input of antenna 11, which transmits a radio signal in the direction of the NNS spacecraft, which calculates the corrections to the on-board time scale of the NNS spacecraft.Antenna 11 receives signals with the values ​​of corrections to the on-board time scale of the NNS spacecraft, transmitted by the SNKA, which are received from the output of antenna 11 to the first input of the PPA 2, then from the second output of the PPA 12 to the first input of the on-board digital computer 13, and then from the second output of the on-board digital computer 13 to the input of the SBSHV 14, which makes corrections to the on-board time scale in order to align it with the system time scale of the NNS.

[0077] FNSP 16 calculates the ephemeris of the NNS spacecraft using the calculated orbital parameters of the NNS spacecraft and the onboard time scale values, and generates a navigation message intended for navigational determinations by the user. The orbital parameters and the time scale values ​​are received by FNSP 16 from the fourth output of the onboard digital computer 13, while the time scale values ​​are received from the SBSHV 14 to the second input of the onboard digital computer 13. The generated navigation message from FNSP 16 is first sent to the fourth input of the onboard digital computer 13, and then from the first output of the onboard digital computer 13 to the second input of the PPA 12, and then from the third output of the PPA 12 to the antenna 17, through which it is transmitted to the users of navigation information.

[0078] In device 1 in Fig. 1, when synchronizing the on-board time scale of the NNS spacecraft with the time scale of the SNSC, synchronized with the time scale of the navigation system, corrections to the on-board time scale of the NNS spacecraft are calculated by using a time synchronization radio signal transmitted by the NNS spacecraft, which is received by antenna 2 and PPA 3. The received radio signal is fed to the first input of the on-board digital computer 4 and then from the fifth output of the on-board digital computer 4 to the SSC 9. The SSC 9 calculates corrections to the on-board time scale of the NNS spacecraft, using the values ​​of the on-board time scale and the orbital parameters of the SNSC, as well as the values ​​of the on-board time scale and the orbital parameters of the NNS spacecraft. Then the SSHV 9 generates a radio signal with corrections to the on-board time scale of the NNS spacecraft, which is fed to the fifth input of the BCVM 4, then from the first output of the BCVM 4 to the second input of the PPA 3 and from the third output of the PPA 3 to the antenna 8, which transmits the radio signal with corrections for reception by the NNS spacecraft.

[0079] The BCVM 4 controls the functioning and interaction of all subsystems of the devices in Fig. 1, and the BCVM 13 controls the subsystems of the devices in Fig. 2.

[0080] Literature

[0081] 1. GLONASS. Principles of design and operation. / Ed. A.I. Petrov, V.N. Kharisov. - M.: Radio Engineering, 2005.

[0082] 2. Patent RU 2390730, Method of ephemeris support for the control process of spacecraft of the global navigation satellite system. / Strelnikov S.V., IPC G01C 21 / 24, published 05 / 27 / 2010, Bulletin No. 15.

[0083] 3. Patent RU 2477836, Method of ephemeris support for the process of controlling spacecraft of the global navigation satellite system. / Strelnikov S.V. IPC G01C 21 / 24 published 20.03.2013, Bulletin No. 8.

[0084] 4. Patent RU 2367910 RF. Method for constructing an orbital-based functional supplement to a global navigation satellite system. / Strelnikov S.V., Mironyuk A.I., IPC G01C 21 / 24, published 20.09.2009, Bulletin No. 26.

[0085] 5. Patent No. 2520714 of the Russian Federation. Method for determining the orbit of a spacecraft. / Strelnikov S.V., Bubnov V.I. Rodionova G.G., IPC B64G 3 / 00, published 06.27.2014, Bulletin No. 18.

Claims

A method for providing ephemeris support for the process of controlling spacecraft of a low-orbit navigation system (LONSS), which consists in the use of a spacecraft on which equipment for synchronizing the on-board time scale with the system time scale of the low-orbit navigation system and equipment for determining the parameters of its orbit using signals from ground-based radio beacons are placed, during orbital flight its on-board time scale is synchronized with the system time scale of the navigation satellite system, signals from ground-based radio beacons are received and orbital parameters are determined from them, a specified accuracy of the orbital parameters of the spacecraft is continuously maintained due to frequent reception and processing of signals from ground-based radio beacons, equipment for generating and transmitting a navigation message for navigational determinations of consumers is installed on the LONSS, characterized in that equipment for generating and transmitting a message is installed on the spacecraft,containing the parameters of its orbit, equipment for synchronizing the on-board time scale with the time scale of the navigation satellite system spacecraft, on which equipment for receiving a message containing the parameters of the orbit of the spacecraft, equipment for synchronizing the on-board time scale with the time scale of the spacecraft are installed, at least four spacecraft are launched into orbit, they are placed in one orbital plane, the on-board equipment of which generates messages in flight containing the parameters of their orbits and units of the on-board time scales, emits messages containing the orbit parameters in the direction of the flight trajectories of the navigation satellite system spacecraft, the equipment of the navigation satellite system spacecraft receives messages containing the orbit parameters, measures the Doppler frequency shift of their signal, calculates the orbital parameters of the navigation satellite system spacecraft based on the measured values ​​of the Doppler frequency shift of the signal of the received message and the orbital parameters of the spacecraft, synchronizes the on-board time scale of the navigation satellite system spacecraft with the time scale of the spacecraft,calculate ephemeris information, generate navigation messages, which are transmitted for navigational determinations to consumers of navigation information,

Images