CN114422065A - High-orbit remote sensing satellite on-satellite time synchronization system and method - Google Patents
High-orbit remote sensing satellite on-satellite time synchronization system and method Download PDFInfo
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Abstract
The invention relates to a satellite-borne time synchronization system and method for a high-orbit remote sensing satellite, and belongs to the technical field of satellite-borne time systems of high-orbit satellites. The invention firstly proposes to utilize the high-orbit GNSS navigation receiving system to carry out planet ground time synchronization in the high orbit, and solves the problems that the high-orbit satellite can only rely on ground to measure and control time correction, the time correction precision is not high, and the operation cost is high. Meanwhile, the instantaneity characteristic of time error acquisition of the navigation receiving system is adopted to calibrate the long-term drift of the high-stability clock source, so that the problem of long-term index drift of the high-stability clock source is solved, and the precision of the satellite clock system is ensured. Then, the accurate time of the satellite is timed by adopting a high-stability clock source, and the problem of low reliability of the high-orbit received GNSS navigation signal is solved.
Description
Technical Field
The invention relates to a satellite-borne time synchronization system and method for a high-orbit remote sensing satellite, and belongs to the technical field of satellite-borne time systems of high-orbit satellites.
Background
The geosynchronous orbit satellite generally adopts the scheme of ground time service, high stable satellite clock time keeping and platform accurate time scale providing, and needs to carry out frequent time synchronization through a ground measurement and control station system and guarantee through complex satellite-ground time alignment and correction measures. The satellite-ground time synchronization precision can be guaranteed to be 1-10 ms every day, and if the satellite-ground time synchronization precision with higher precision needs to be guaranteed, the ground measurement and control station needs to perform 1 or continuous times of time correction at intervals of one day or even several hours. With the development and application of the high-orbit remote sensing satellite, the requirement of the load on the time precision of the satellite is gradually increased, meanwhile, the requirement of a user on the autonomy of the satellite is also gradually increased, and the existing method for calibrating the system through the ground measurement and control station is difficult to adapt to the development requirement of the high-precision and autonomy time synchronization of the high-orbit remote sensing satellite.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the system and the method are high-precision time synchronization system and method based on space-based independence, microsecond or even nanosecond-level satellite-ground time synchronization can be achieved in orbit independence without depending on calibration operation of a ground measurement and control station, dependence of a satellite on the ground is reduced, and application flexibility and autonomous operation capability of the satellite can be effectively improved.
The technical solution of the invention is as follows:
an on-satellite time synchronization system of a high-orbit remote sensing satellite comprises a high-orbit GNSS navigation receiving system, a high-stability clock source, a data management system and a bus terminal;
the bus terminals are divided into high-precision application demand bus terminals and conventional precision application demand bus terminals; the time precision of the high-precision application demand bus terminal is in the order of mu s; the time precision of the bus terminal is required to be ms magnitude by conventional precision application;
the high-orbit GNSS navigation receiving system is used for receiving navigation information of a navigation satellite constellation and acquiring time information of standard time as a reference for calibrating a satellite-ground system according to the received navigation information;
the high-orbit GNSS navigation receiving system converts the acquired time information of the standard time into hardware pulse-per-second information and a whole second time code corresponding to the hardware pulse-per-second information;
the high-orbit GNSS navigation receiving system transmits the converted hardware second pulse information to a high-stability clock source through a signal wire;
the high-orbit GNSS navigation receiving system transmits the whole second time code corresponding to the converted hardware second pulse information to the high-stability clock source through a bus;
the high-stability clock source is used for receiving hardware second pulse information and a second-integer time code transmitted by the high-orbit GNSS navigation receiving system, calibrating an internal clock by using the received hardware second pulse information and the second-integer time code, and generating a time reference which can be used on the satellite;
the high-stability clock source converts the generated time reference used on the satellite into hardware second pulse information and a second-whole time code, the hardware second pulse information is transmitted to the high-precision application demand bus terminal through a signal line, and the second-whole time code is transmitted to the high-precision application demand bus terminal through a bus, so that the time reference is provided for the high-precision application demand bus terminal;
the data management system sends the current time of the data management system to a high-stability clock source through a bus, the high-stability clock source calibrates the current time of the data management system by utilizing a generated time reference used on a satellite, time correction time difference is produced, the generated time correction time difference is transmitted to the data management system through the bus, the data management system completes time calibration according to the received time correction time difference, the calibrated time is sent to a conventional precision application demand bus terminal, and the time reference is provided for the conventional precision application demand bus terminal.
Preferably, the time precision of the high-precision application demand bus terminal is 1-40 mus, and the time precision of the conventional precision application demand bus terminal is 1-10 ms.
Preferably, the high-stability clock source further corrects the long-term clock drift of the high-stability clock according to the received hardware second pulse information of the high-orbit GNSS navigation receiving system.
Preferably, the bus terminals required by the conventional precision application are used for maintaining the conventional operation of the satellite, and receive the time reference of the conventional precision broadcasted by the data management system through the bus, and the time reference of the bus terminals comprises a thermal control subsystem, a measurement and control subsystem, a data transmission subsystem and the like.
Preferably, the bus terminal required by the high-precision application participates in load imaging application and ensures imaging quality, and comprises a load subsystem, a control subsystem and other subsystems with high requirements on time precision.
Preferably, the method for acquiring the time information of the standard time by the high-orbit GNSS navigation receiving system according to the received navigation information includes: the high-orbit GNSS navigation system is configured to receive GNSS navigation signals propagated by the earth in an opposite direction, information such as the distance between the high-orbit GNSS navigation system and navigation satellites and navigation messages is resolved, and time information of the satellites at the current moment is obtained.
A method for synchronizing time on a high orbit remote sensing satellite comprises the following steps:
firstly, a high-orbit GNSS navigation receiving system receives navigation information of a navigation satellite constellation, and acquires time information of standard time according to the received navigation information to be used as a reference for calibrating a satellite-ground system;
secondly, the high-orbit GNSS navigation receiving system converts the acquired time information of the standard time into hardware pulse-per-second information and a whole second time code corresponding to the hardware pulse-per-second information, transmits the converted hardware pulse-per-second information to the high-stability clock source through a signal line, and transmits the whole second time code corresponding to the converted hardware pulse-per-second information to the high-stability clock source through a bus;
thirdly, the high-stability clock source receives hardware second pulse information and a second-integer time code transmitted by the high-orbit GNSS navigation receiving system, calibrates a clock in the high-stability clock source according to the received hardware second pulse information and the second-integer time code, generates a time reference which can be used on the satellite, and maintains the generated time reference which is used on the satellite in a time-keeping manner; the high-stability clock source provides a high-stability clock signal for the high-orbit GNSS navigation receiving system by utilizing the high-stability clock;
fourthly, the high-stability clock source converts the generated time reference used on the satellite into hardware pulse-per-second information and a whole-second time code corresponding to the hardware pulse-per-second information, and provides the hardware pulse-per-second information for a high-precision application demand bus terminal with high time requirement precision;
fifthly, time calibration is carried out on the high-stability clock source and the data management system through a bus, the data management system obtains calibrated time information through the calibration of the high-stability clock source, and a time reference of conventional precision in the data management system is maintained;
sixthly, the data management system distributes the time information calibrated by the high-stability clock source to a bus terminal with the conventional precision application requirement in a broadcasting mode for use;
seventhly, keeping the generated time reference used on the satellite by the high-stability clock source in time;
eighthly, correcting long-term clock drift of the high-stability clock by using hardware second pulse information of the high-orbit GNSS navigation receiving system by the high-stability clock source;
and step nine, the high-stability clock source provides a high-stability clock signal to a system which needs to use the high-stability clock on the satellite.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention firstly proposes to utilize a GNSS navigation system to carry out planet ground time synchronization in high orbit, and solves the problems that the high orbit satellite can only rely on ground to measure and control time correction, the time correction precision is not high, and the operation cost is high. Meanwhile, the instantaneity characteristic of the time error of the navigation receiving system is adopted to calibrate the long-term drift of the high-stability clock source, so that the problem of the long-term index drift of the high-stability clock is solved, and the precision of the satellite clock system is ensured. The high-stability clock is adopted to keep time for the accurate time of the satellite, and the problem of low reliability of high-orbit received GNSS navigation signals is solved.
(2) Compared with the common high-orbit remote sensing satellite, the high-orbit GNSS navigation receiving system is added, and the method can be used for autonomous time correction on the satellite. Compared with the prior remote sensing satellite, the method transfers the core equipment of time keeping and time service from the navigation receiving system to the high-stability clock source, thereby improving the precision and reliability of the system. The tracing and calibration of the high-stability clock signal precision by utilizing the second pulse of the navigation receiving system are added, and the problem of error caused by time offset after long-time operation in the autonomous time keeping and time service process is solved.
(3) The on-satellite time synchronization system and the on-satellite time synchronization method are a design and a scheme with extremely low dependence on ground time correction, low constraint demand degree on weak signals and low reliability of a high-orbit GNSS navigation receiving system, time, personnel and economic cost of ground operation and control management are reduced, the system is high in reliability and high in precision, can independently, safely and stably operate, meets the requirements of high-orbit remote sensing satellites on satellite-ground time synchronization precision and on-satellite time maintenance precision, and has good application value.
(4) Aiming at the autonomous requirements and characteristics of the high-orbit remote sensing satellite on the satellite-ground time synchronization precision and the on-satellite time calibration, the satellite-ground time calibration can be autonomously completed and maintained at the precision of microseconds or even nanoseconds during the orbit operation period of the satellite, and the satellite can be completely separated from the ground measurement and control time calibration and independently and stably work for a long time. The time synchronization system effectively reduces the cost of ground measurement, control and operation while meeting the time precision and autonomous requirements of the high-orbit remote sensing satellite, and improves the usability and the usability of the satellite.
(5) The high-stability clock source provides a high-stability clock signal to a system which needs to use a high-stability clock on a satellite, ensures the stability of the clock application and the phase consistency of the clock, and improves the synchronization precision.
Drawings
Fig. 1 is a schematic composition diagram of the satellite time synchronization system of the high orbit remote sensing satellite of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.
An on-satellite time synchronization system of a high-orbit remote sensing satellite comprises a high-orbit GNSS navigation receiving system, a high-stability clock source, a data management system and a bus terminal;
the bus terminals are divided into high-precision application demand bus terminals and conventional precision application demand bus terminals; the time precision of the high-precision application demand bus terminal is in a mu s magnitude order, preferably 1-40 mu s, and the time precision of the conventional precision application demand bus terminal is in an ms magnitude order, preferably 1-10 ms;
the high-orbit GNSS navigation receiving system is used for receiving navigation information of a navigation satellite constellation and acquiring time information of standard time as a reference for calibrating a satellite-ground system according to the received navigation information, namely, the high-orbit GNSS navigation system is configured to receive GNSS navigation signals propagated by the earth in opposite directions, and information such as distance between the high-orbit GNSS navigation system and navigation messages is resolved to acquire time information of the satellite at the current time; the high-orbit GNSS navigation receiving system converts the acquired time information of the standard time into hardware pulse per second information and a whole second time code corresponding to the pulse per second information; the high-orbit GNSS navigation receiving system transmits the converted hardware second pulse information to the high-stability clock source through a signal line, and transmits the whole second time code corresponding to the converted hardware second pulse information to the high-stability clock source through a bus (a common bus is 1553B or a CAN bus);
the high-stability clock source receives hardware second pulse information and a second-integer time code transmitted by the high-orbit GNSS navigation receiving system, and the internal time reference of the high-stability clock source is calibrated by utilizing the received hardware second pulse information and the second-integer time code through an internal time service module to generate a time reference which can be used on the satellite so as to finish time service operation; the high-stability clock of the high-stability clock source corrects long-term clock drift (frequency difference compensation, phase compensation and the like) of the high-stability clock by using the clock taming module according to the received hardware second pulse information of the high-orbit GNSS navigation receiving system, so that the long-term clock stability of the high-stability clock is ensured;
the high-stability clock source converts the generated time reference used on the satellite into hardware second pulse information and a whole second time code corresponding to the hardware second pulse, and transmits the hardware second pulse information and the whole second time code to the high-precision application demand bus terminal with high time requirement precision through the signal line and the bus respectively, so that time calibration is provided for the high-precision application demand bus terminal with high time requirement precision. The high-stability clock source is also used for carrying out time calibration on the data management system through the bus, firstly, the data management system sends the current time reference of the data management system to the high-stability clock source through the bus, the high-stability clock source calibrates the time reference of the data management system by utilizing the generated time reference used on the satellite, and the time-correcting time difference is transmitted to the data management system through the bus.
The high-stability clock source keeps the time of the generated time reference used on the satellite through the time keeping module, and the accuracy of the self time information is maintained when the high-orbit GNSS navigation receiving system has no second pulse information and whole second time code for a long time by utilizing the characteristic of the self high-stability clock.
The high-stability clock source outputs a stable clock signal to other systems or equipment (including a high-orbit GNSS navigation system, a data management system, a high-precision application demand bus terminal and the like) of the satellite which needs the high-stability clock.
The data management system is communicated with a high-stability clock source through a bus to finish timing action, and the time reference (the precision is generally 1-10 ms) for maintaining the satellite operation with conventional precision is obtained through timing. The calibration method comprises the following steps: the data management system transmits the time code of the data management system to the high-stability clock source, the high-stability clock source compares the received time code transmitted by the data management system with the time reference maintained in the high-stability clock source to obtain the time difference information, then the obtained time difference information is fed back to the data management system, the data management system calibrates the time information in the data management system according to the received time difference information to obtain the calibrated time information, and the time reference with the conventional precision in the data management system is maintained. The data management system broadcasts the acquired and maintained time reference with the conventional precision to a bus terminal with the conventional precision application requirement through a bus (generally a 1553B bus or a CAN bus).
The conventional precision application requires that the bus terminals receive the conventional precision time reference broadcasted by the data management system through the bus as the time reference of the bus terminals.
The high-precision application demand bus terminal receives hardware second pulse information and second-integer time codes sent by a high-stability clock source through a signal line and a bus, and obtains high-precision time references which are used as the time references of the bus terminals.
The bus terminal required by the conventional precision application is generally a bus terminal for maintaining the basic operation of the satellite, and comprises a thermal control subsystem, a measurement and control subsystem, a data transmission subsystem and other satellite platform operation systems;
the bus terminal required by high-precision application generally participates in load imaging application and ensures imaging quality, and comprises satellite load imaging related systems such as a load subsystem, a control subsystem and other subsystems with high requirements on time precision. A bus terminal with high precision application requirements uses a high-stability clock signal provided by a high-stability clock source;
the bus terminals are all used as users of time.
The equipment for receiving the pulse per second comprises a high-stability clock source, a data management system, a high-precision application demand bus terminal and the like, and a signal using the pulse per second is led out to the surface of the equipment through an equipment connector, so that the time delay precision of the received and used pulse per second is conveniently tested and corrected, the high-precision testability is improved, and the accuracy and the reliability of the high-precision time application are ensured.
A method for synchronizing time on a high orbit remote sensing satellite comprises the following steps:
the method comprises the steps that firstly, a high-orbit GNSS navigation receiving system receives navigation information of a navigation satellite constellation, and obtains time information of standard time according to the received navigation information to be used as a reference for calibrating a satellite-ground system;
secondly, the high-orbit GNSS navigation receiving system converts the acquired time information of the standard time into hardware second pulse information and a whole second time code corresponding to the hardware second pulse information, transmits the converted hardware second pulse information to the high-stability clock source through a signal wire, and transmits the whole second time code corresponding to the converted hardware second pulse information to the high-stability clock source through a 1553B or CAN bus;
thirdly, the high-stability clock source receives hardware second pulse information and a second-integer time code transmitted by the high-orbit GNSS navigation receiving system, calibrates a clock in the high-stability clock source according to the received hardware second pulse information and the second-integer time code, generates a time reference which can be used on the satellite, and maintains the generated time reference which is used on the satellite in a time-keeping manner; and the high-stability clock source provides a high-stability clock signal for the high-orbit GNSS navigation receiving system by utilizing the high-stability clock at the same time, and the high-stability clock signal is used as a clock for running software and hardware.
Fourthly, the high-stability clock source converts the generated time reference used on the satellite into hardware pulse-per-second information and a whole-second time code corresponding to the hardware pulse-per-second information, and provides the hardware pulse-per-second information for a high-precision application demand bus terminal with high time requirement precision;
fifthly, the high-stability clock source is subjected to time calibration through a bus and a data management system, the data management system obtains calibrated time information through the calibration of the high-stability clock source, and the time information can be used for maintaining the operation and maintenance of a bus terminal required by the conventional precision application of a satellite platform;
sixthly, the data management system distributes the time information calibrated by the high-stability clock source to a bus terminal with the requirement of conventional precision application in a broadcasting mode;
and seventhly, the high-stability clock source keeps the generated time reference used on the satellite in a time-keeping mode through a time-keeping module, and the high-stability clock characteristic is utilized to keep the accuracy of the time of the high-orbit GNSS navigation receiving system when the high-orbit GNSS navigation receiving system does not have pulse per second information and whole second time codes for a long time.
The bus terminal required by the conventional precision application is generally a bus terminal for maintaining the basic operation of the satellite, and comprises a thermal control subsystem, a measurement and control subsystem, a data transmission subsystem and other satellite platform operation systems;
the bus terminal required by high-precision application is generally used for participating in load imaging application and ensuring imaging, and comprises satellite load imaging related systems such as a load subsystem, a control subsystem and other subsystems with high requirements on time precision;
the high-precision application demand bus terminal, the high-orbit GNSS navigation receiving system and the data management system use a high-stability clock signal provided by a high-stability clock source;
the bus terminals are used as time users.
(1) Time generation
The satellite time reference of the satellite-to-satellite time synchronization system of the high-orbit remote sensing satellite receives GNSS navigation signals from the opposite side of the earth through a high-orbit GNSS navigation receiving system, measures and solves the current time moment, and converts the GNSS time into the time reference used by a satellite platform. The time precision can be guaranteed to be 1-50 mu s.
(2) Time tracing and calibration of highly stable clocks
And aligning the time reference of the high-stability clock of the high-orbit remote sensing satellite through the time reference of the high-orbit GNSS. The alignment mode adopts hardware second pulse transmission with high precision, and the time precision can be ensured to be in the level of +/-1 mu s or even ns. And transmitting the second pulse of the hardware, and transmitting the whole second time code of the time reference of the high-orbit GNSS to a high-stability clock source through a data bus of a satellite platform. Therefore, the accurate transmission of the high-precision satellite-ground time reference to the high-stability clock source is completed.
After the high-stability clock source receives the hardware second pulse, the time-keeping precision and the high-stability clock precision are calibrated by utilizing the non-accumulation and front-back irrelevance of the second pulse time precision, and the accumulated time error caused by the long-term drift and the long-term drift deviation of the high-stability clock are corrected, so that the accurate correction of the satellite time reference and the high-stability clock source is realized.
(3) High stability time keeping and maintaining
The high-orbit remote sensing satellite realizes the precision of satellite platform timekeeping by configuring a highly stable clock, generally a hydrogen clock, a rubidium clock or a constant temperature crystal oscillator and the like. Taking rubidium clock as an example, 10MHz clock output, long-term stability is + -1 × 10-13The time is kept by the clock, so that the maximum time change of 1 mu s in 1 day can be ensured. Since the high-orbit GNSS navigation receiving system is weak in receiving the navigation signal transmitted from the earth and poor in reliability guarantee, an irregular time discontinuous state may exist, and at this time, the non-instantaneous transient dependence on the navigation receiving system can be reduced by the punctuality and maintenance of high stability time.
(4) Time service of satellite platform
Terminals of the high-precision remote sensing satellite with high-precision time application requirements are mainly load subsystems (such as an optical load subsystem of the optical remote sensing satellite and a microwave load subsystem of the microwave remote sensing satellite) and control subsystems with high requirements on satellite attitude and orbit control precision, and time references of the high-precision application requirement bus terminals are aligned through the time reference of a high-stability clock source. The alignment mode adopts hardware second pulse transmission with high precision, and the time precision can be guaranteed to be +/-1 mu s. And when the hardware second pulse is transmitted, the whole second time code of the high-stability clock source reference is transmitted to the load subsystem and the control subsystem through a data bus of the satellite platform. Therefore, the accurate calibration of the time system of the bus terminal required by the high-precision application of the satellite is completed.
The high-orbit remote sensing satellite platform generally has some terminals with low sensitivity to time precision, the terminals are irrelevant to the precision of load application and are mainly used for ensuring the basic and reliable operation of the satellite platform, such as a measurement and control subsystem, a thermal control subsystem, a total circuit subsystem, a power supply subsystem, a data transmission subsystem, a digital tube computer, a remote unit and the like in a data management system, and the bus terminals required by the conventional precision application can meet the time precision requirement through time correction of the data management system. Firstly, the data management system is calibrated through a high-stability clock source, and the timing mode comprises forced timing, autonomous timing and the like. And then, after the data management system is in time keeping, time calibration is carried out on a data management computer, a remote unit and the like in the measurement and control subsystem, the thermal control subsystem, the overall circuit subsystem, the power supply subsystem, the data transmission subsystem and the data management system through the data bus.
(4) Satellite time system test interface
The time service precision of the satellite time system of the high-orbit remote sensing satellite can be guaranteed to be 1 mu s even ns level through hardware second pulse. When a bus terminal such as a load subsystem and a control subsystem which are required by high-precision application receive the pulse per second, internal hardware and software processing are carried out, and finally the pulse per second precision of the application has certain delay. In order to confirm the accurate value of the delay precision, the pulse per second finally applied to the high-precision application demand bus terminal is led out to a test interface of the equipment through measures such as shunting, and the time delay precision from the pulse per second output by the high-orbit GNSS navigation system to the pulse per second finally applied to the high-precision application demand bus terminal is conveniently and directly measured.
Examples
As shown in fig. 1, a satellite of a certain high-orbit microwave remote sensing satellite is provided with a high-orbit GNSS navigation receiving system, the system automatically obtains time information of the satellite at the current time by receiving navigation satellite navigation radio frequency signals of a BDS constellation and a GPS constellation transmitted from the opposite side of the earth, and completes time synchronization with each system on the ground by the BDS constellation and the GPS constellation. The clock required by the operation and calculation of the high-orbit GNSS navigation receiving system is provided and guaranteed by the high-stability clock of the high-stability clock source configured on the satellite. This step completes the time unification of the satellite with the ground.
And the high-orbit GNSS navigation receiving system converts the acquired time information of the standard time into hardware pulse-per-second information and a whole second time code corresponding to the hardware pulse-per-second information. And the high-orbit GNSS navigation receiving system transmits the converted hardware second pulse information to the high-stability clock source through the signal wire, and transmits the whole second time code corresponding to the converted hardware second pulse information to the high-stability clock source through a 1553B bus. The high-stability clock source receives hardware second pulse information and a second-integer time code transmitted by the high-orbit GNSS navigation satellite system, the internal time information of the high-stability clock source is calibrated by the aid of the internal time service module through the received hardware second pulse information and the second-integer time code, a time reference which can be used on the satellite is generated, and time service operation is completed.
The high-stability clock source converts the generated time reference used on the satellite into hardware pulse per second information and a whole second time code, and respectively transmits the hardware pulse per second information and the whole second time code to a high-precision application demand bus terminal 1, a bus terminal 2, a bus … and a bus terminal n which have high time requirement precision through a signal line and a bus. The calibration accuracy can reach the order of mu s.
The high-stability clock source is also used for carrying out time calibration on the data management system through the bus, firstly, the data management system sends the current time reference of the data management system to the high-stability clock source through the bus, the high-stability clock source calibrates the time reference of the data management system by utilizing the generated time reference used on the satellite, and the time-correcting time difference is transmitted to the data management system through the bus. The data management system is communicated with the high-stability clock source through the bus to finish timing action, and the time reference (the precision is generally 1-10 ms) for maintaining the satellite operation with the conventional precision is obtained through timing.
The data management system broadcasts the acquired and maintained time reference with the conventional precision to a bus terminal a, a bus terminal B and a bus terminal m which are required by the application of the conventional precision through a 1553B bus. The terminal on the remote sensing satellite comprises a measurement and control subsystem, a thermal control subsystem, a data transmission subsystem, a total circuit subsystem, a control subsystem, a remote unit of a data management system and the like, and time calibration is provided for the subsystems. The calibration accuracy can reach ms magnitude.
The high-stability clock source keeps the time of the generated time reference used on the satellite through the time keeping module, and the accuracy of the time of the high-stability clock source is maintained when the high-orbit GNSS navigation receiving system does not have pulse per second information and whole second time codes for a long time by utilizing the characteristic of the high-stability clock. Because the high-orbit GNN navigation receiving system receives navigation signals of navigation constellations opposite to the earth, the navigation signals are signals leaked from side lobes of the navigation satellites, the navigation receiving system is possible to be unlocked for tens of minutes to hours, the navigation receiving system cannot provide pulse-per-second signals and corresponding whole-second time codes for the high-stability clock source, and the high-stability clock source extrapolates and maintains self-maintained time information through a self high-stability clock.
According to the received hardware second pulse information of the high-orbit GNSS navigation receiving system, the high-stability clock of the high-stability clock source corrects long-term clock drift (frequency difference compensation, phase compensation and the like) of the high-stability clock source by using the clock taming module, and the clock stability of the high-stability clock is ensured.
The high-stability clock source outputs a stable clock signal to other systems or equipment of the satellite which need the high-stability clock.
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. The on-satellite time synchronization system of the high orbit remote sensing satellite is characterized in that: the satellite time synchronization system comprises a high-orbit GNSS navigation receiving system, a high-stability clock source, a data management system and a bus terminal;
the bus terminals are divided into high-precision application demand bus terminals and conventional precision application demand bus terminals; the time precision of the high-precision application demand bus terminal is in the order of mu s; the time precision of the bus terminal is required to be ms magnitude by conventional precision application;
the high-orbit GNSS navigation receiving system is used for receiving navigation information of a navigation satellite constellation and acquiring time information of standard time as a reference for calibrating a satellite-ground system according to the received navigation information;
the high-orbit GNSS navigation receiving system converts the acquired time information of the standard time into hardware pulse-per-second information and a whole second time code corresponding to the hardware pulse-per-second information;
the high-orbit GNSS navigation receiving system transmits the converted hardware second pulse information to a high-stability clock source through a signal wire;
the high-orbit GNSS navigation receiving system transmits the whole second time code corresponding to the converted hardware second pulse information to the high-stability clock source through a bus;
the high-stability clock source is used for receiving hardware second pulse information and a second-integer time code transmitted by the high-orbit GNSS navigation receiving system, calibrating an internal clock by using the received hardware second pulse information and the second-integer time code, and generating a time reference which can be used on the satellite;
the high-stability clock source converts the generated time reference used on the satellite into hardware second pulse information and a second-whole time code, the hardware second pulse information is transmitted to the high-precision application demand bus terminal through a signal line, and the second-whole time code is transmitted to the high-precision application demand bus terminal through a bus, so that the time reference is provided for the high-precision application demand bus terminal;
the data management system sends the current time of the data management system to a high-stability clock source through a bus, the high-stability clock source calibrates the current time of the data management system by utilizing a generated time reference used on a satellite, time correction time difference is produced, the generated time correction time difference is transmitted to the data management system through the bus, the data management system completes time calibration according to the received time correction time difference, the calibrated time is sent to a conventional precision application demand bus terminal, and the time reference is provided for the conventional precision application demand bus terminal.
2. The high earth orbit remote sensing satellite on-board time synchronization system of claim 1, characterized in that:
the time precision of the bus terminal required by high-precision application is 1-40 mu s, and the time precision of the bus terminal required by conventional precision application is 1-10 ms.
3. The high earth orbit remote sensing satellite on-board time synchronization system of claim 1, characterized in that:
and the high-stability clock source corrects the long-term clock drift of the high-stability clock according to the received hardware second pulse information of the high-orbit GNSS navigation receiving system.
4. The high earth orbit remote sensing satellite on-board time synchronization system of claim 1, characterized in that:
the bus terminal with the conventional precision application requirement is used for maintaining the conventional operation of the satellite, receives the time reference of the conventional precision broadcasted by the data management system through the bus, and is used as the time reference of the bus terminals, and comprises a thermal control subsystem, a measurement and control subsystem, a data transmission subsystem and the like.
5. The high earth orbit remote sensing satellite on-board time synchronization system of claim 1, characterized in that:
the bus terminal with high precision application requirement participates in load imaging application and ensures imaging quality, and comprises a load subsystem, a control subsystem and other subsystems with high time precision requirement.
6. The high earth orbit remote sensing satellite on-board time synchronization system of claim 1, characterized in that:
the method for acquiring the time information of the standard time by the high-orbit GNSS navigation receiving system according to the received navigation information comprises the following steps: the high-orbit GNSS navigation system is configured to receive GNSS navigation signals propagated by the earth in an opposite direction, information such as the distance between the high-orbit GNSS navigation system and navigation satellites and navigation messages is resolved, and time information of the satellites at the current moment is obtained.
7. A method for synchronizing time on a high-orbit remote sensing satellite is characterized by comprising the following steps:
firstly, a high-orbit GNSS navigation receiving system receives navigation information of a navigation satellite constellation, and acquires time information of standard time according to the received navigation information to be used as a reference for calibrating a satellite-ground system;
secondly, the high-orbit GNSS navigation receiving system converts the acquired time information of the standard time into hardware pulse-per-second information and a whole second time code corresponding to the hardware pulse-per-second information, transmits the converted hardware pulse-per-second information to the high-stability clock source through a signal line, and transmits the whole second time code corresponding to the converted hardware pulse-per-second information to the high-stability clock source through a bus;
thirdly, the high-stability clock source receives hardware second pulse information and a second-integer time code transmitted by the high-orbit GNSS navigation receiving system, calibrates a clock in the high-stability clock source according to the received hardware second pulse information and the second-integer time code, generates a time reference which can be used on the satellite, and maintains the generated time reference which is used on the satellite in a time-keeping manner; the high-stability clock source provides a high-stability clock signal for the high-orbit GNSS navigation receiving system by utilizing the high-stability clock;
fourthly, the high-stability clock source converts the generated time reference used on the satellite into hardware pulse-per-second information and a whole-second time code corresponding to the hardware pulse-per-second information, and provides the hardware pulse-per-second information for a high-precision application demand bus terminal with high time requirement precision;
fifthly, time calibration is carried out on the high-stability clock source and the data management system through a bus, the data management system obtains calibrated time information through the calibration of the high-stability clock source, and a time reference of conventional precision in the data management system is maintained;
sixthly, the data management system distributes the time information calibrated by the high-stability clock source to a bus terminal with the conventional precision application requirement in a broadcasting mode for use;
seventhly, keeping the generated time reference used on the satellite by the high-stability clock source in time;
eighthly, correcting long-term clock drift of the high-stability clock by using hardware second pulse information of the high-orbit GNSS navigation receiving system by the high-stability clock source;
and step nine, the high-stability clock source provides a high-stability clock signal to a system which needs to use the high-stability clock on the satellite.
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