Test method and test system for satellite time-frequency reference small-step frequency modulation function

Abstract

The invention provides a test method and a test system for a satellite time-frequency reference small-step frequency modulation function. The test method comprises the following steps: setting initial clock information of a tested satellite, wherein the initial clock information comprises initial time and initial frequency; obtaining a clock frequency adjustment strategy of the tested satellite according to the clock deviation information between the reference clock information and the initial clock information of the test end; continuously adjusting the clock frequency of the measured satellite according to the clock frequency adjustment strategy; wherein each frequency adjustment amplitude of the clock is smaller than or equal to a first threshold value; and in the continuous adjustment process, completing the test of the tested satellite according to the distance measurement information between the test end and the tested satellite. The method can verify the influence of satellite small-step frequency modulation on each communication load and navigation load, and is suitable for function and performance test and verification of a communication fusion system.

Description

Technical Field

[0001] The present disclosure relates to the technical field of time and frequency measurement of low-orbit satellites, and specifically to a test method for a satellite time and frequency reference small-step frequency modulation function, an on-board test system, a ground test system, and a test system. Background Art

[0002] The satellites in orbit that require high precision and high stability in their time and frequency systems are mainly navigation satellites in medium and high orbits. There has been a lot of research on high-precision time and frequency for navigation satellites. The core requirement for high-throughput communication satellites in medium and high orbits is to ensure the accuracy of satellite-ground time synchronization.

[0003] In recent years, with the rapid development of low-orbit large-scale constellation technology, the time and frequency generation technology of low-orbit satellites and the corresponding test methods have also become a hot topic of research. However, due to factors such as the manufacturing cost, overall mass and volume of satellites, large-scale low-orbit constellations are no longer suitable for using the onboard atomic clocks commonly used on navigation satellites as frequency sources. The time and frequency systems of low-orbit satellites are developing rapidly in the direction of high performance, miniaturization and low cost, which correspondingly requires improvements and innovations in the test methods of low-orbit satellite time and frequency systems. However, traditional testing methods can only achieve simple frequency or phase modulation functions for satellites, and cannot effectively verify the ability of the satellite time and frequency reference to autonomously perform small-step frequency modulation. Summary of the invention

[0004] It would be advantageous to provide a mechanism that mitigates, alleviates or eliminates at least one of the problems discussed above.

[0005] In the first aspect, a test method for the small-step frequency modulation function of a satellite time-frequency reference is provided. The test method includes: setting the initial clock information of the satellite under test, the initial clock information including the initial time and the initial frequency; obtaining the clock frequency adjustment strategy of the satellite under test according to the clock deviation information between the reference clock of the test end and the initial clock information; continuously adjusting the clock frequency of the satellite under test according to the clock frequency adjustment strategy; wherein the frequency adjustment amplitude of each clock is less than or equal to the first threshold; during the continuous adjustment process, completing the test of the satellite under test according to the ranging information between the test end and the satellite under test.

[0006] In the second aspect, an on-board test system with a satellite time and frequency reference small-step frequency modulation function is provided, which is used for the satellite under test to implement the above test method. The on-board test system includes: a satellite-borne rubidium clock, which is used to set the initial clock information of the satellite under test, and the initial clock information includes the initial time and the initial frequency; a satellite-borne timing receiver, which is used to receive the injection message transmitted by the test end, and the injection message includes the clock deviation information between the reference clock of the test end and the initial clock information; a navigation enhancement processor, which is used to generate a clock frequency adjustment strategy according to the clock deviation information and the satellite equipment delay difference parameter, and continuously adjust the clock frequency of the satellite under test according to the clock frequency adjustment strategy; a communication payload, which is used to generate the ranging information between the test end and the satellite under test during the continuous adjustment process.

[0007] In a third aspect, a ground test system for the small-step frequency modulation function of a satellite time and frequency reference is provided, which is used for a test end to implement the above test method, including: a ground test hydrogen clock, used to generate a reference clock of the test end; a navigation data processing system, used to calculate in real time the clock deviation information between the reference clock and the initial clock information of the measured satellite, and generate a clock frequency adjustment strategy and adjustment instructions of the measured satellite according to the clock deviation information and the small-step frequency modulation strategy; a communication network simulator, used to inject the clock frequency adjustment strategy and the adjustment instructions to the measured satellite; a time interval frequency counter, used to measure the time difference between the time of the measured satellite and the reference clock; a phase comparator, used to measure the frequency difference between the frequency of the measured satellite and the reference clock; a navigation enhancement ground terminal and a ground communication terminal, used to generate ranging information between the test end and the measured satellite during the continuous adjustment process.

[0008] In a fourth aspect, a test system for the small-step frequency modulation function of a satellite time and frequency reference is provided. The test system includes the above on-board test system and the above ground test system.

[0009] It should be understood that the invention summary is not intended to identify the key or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of some embodiments of the present disclosure in the accompanying drawings, in which: Figure 1 A flow chart showing a method for testing a satellite time and frequency reference small-step frequency modulation function according to an embodiment of the present disclosure is shown; Figure 2A flowchart of a satellite time and frequency reference small-step frequency modulation service function in one embodiment of the present disclosure is shown; Figure 3 A schematic diagram showing a test system for small-step frequency modulation of a satellite time and frequency reference in a satellite autonomous control mode in an embodiment of the present disclosure is shown; and Figure 4 A schematic diagram of a test system for small-step frequency modulation of a satellite time-frequency reference in a ground control mode in an embodiment of the present disclosure is shown.

[0011] Description of the accompanying drawings in the specific implementation manner: 310. Navigation data processing system; 320. Ground testing of hydrogen clock; 330. Communication network simulator; 340. Phase comparison instrument; 350. Navigation Enhancement Ground Terminal; 360. Ground communication terminal; 370. Satellite-borne rubidium clock; 380. Navigation enhancement processor; 390. Communication load; 3110. Satellite-borne timing receiver. DETAILED DESCRIPTION

[0012] The principle of the present disclosure will now be described with reference to some embodiments. It should be understood that the description of these embodiments is only for illustrative purposes, and helps those skilled in the art to understand and implement the present disclosure, without any limitation to the scope of the present disclosure. The disclosure described herein can be implemented in a manner different from that described below.

[0013] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0014] References in this disclosure to "one embodiment," "an embodiment," "an exemplary embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in conjunction with an exemplary embodiment, whether or not explicitly described, those skilled in the art will recognize that such feature, structure, or characteristic affects incorporation into other embodiments.

[0015] It should be understood that although the terms "first" and "second" etc. may be used to describe various elements herein, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the listed terms.

[0016] The terms used herein are only for describing specific embodiments, rather than for limiting exemplary embodiments. The singular forms "one", "an", and "the" used herein also include plural forms, unless the context clearly indicates otherwise. "A group of elements" or "element set" used herein is intended to include one or more elements. It should also be understood that the terms "include", "comprise", "have", "have", "include" and / or "include", when used herein, specify the presence of the features, elements and / or parts, etc., but do not exclude the presence or addition of one or more other features, elements, parts and / or combinations thereof.

[0017] As used in this disclosure, the term "circuitry" may refer to one or more or all of the following: (a) Hardware circuit implementation only (e.g., implementation only in analog and / or digital circuits) (b) a combination of hardware circuitry and software, such as (where applicable): (i) a combination of analog and / or digital hardware circuitry and software / firmware; and (ii) any part of a hardware processor (including a digital signal processor) with software, software and memory that work together to enable a device such as a mobile phone or server to perform various functions, and (c) A hardware circuit and / or processor, such as a microprocessor or portion of a microprocessor, that requires software (eg, firmware) to operate, but where software is not required for operation, the software may not be present.

[0018] This definition of circuitry applies to all uses of this term in this disclosure, including in any claims. As another example, as used in this disclosure, the term circuitry also includes an implementation of merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also includes, for example, if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing network device.

[0019] As used herein, the term "communication network" refers to a network that complies with any appropriate communication standard, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), New Radio (NR), Non-terrestrial Network (NTN), etc. In addition, the communication between the terminal equipment and the network equipment in the communication network can be performed according to any appropriate generation of communication protocols, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), future sixth generation (6G) communication protocols, and / or any other protocols currently known or to be developed in the future. The embodiments of the present disclosure can be applied in satellite communication systems. In view of the rapid development in communication, there will certainly be future types of communication technologies and systems, and the present disclosure can be implemented with these technologies and systems. It should not be considered that the scope of the present disclosure is limited to the aforementioned system.

[0020] The terms "satellite equipment" and "network equipment" used in this article refer to a node set on a satellite or ground segment in a satellite communication network. The terminal device accesses the network through this node and receives services from it. Depending on the terms and technologies applied, satellite equipment and network equipment may refer to a base station (BS) or access point (AP) as a satellite payload, such as a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also known as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), and a relay node. An example of a relay node may be an integrated access and backhaul (IAB) node. The distributed unit (DU) part of the IAB node can perform the functions of a "satellite equipment" and a "network equipment", and can therefore be operated as a satellite equipment and a network equipment. In the following description, the terms "satellite equipment", "network equipment", "BS" and "node" may be used interchangeably.

[0021] The term "terminal" or "terminal device" refers to any terminal device capable of wireless communication. As an example and not a limitation, a terminal device may also be referred to as a communication device, a user equipment (UE), a user station (SS), a portable user station, a mobile station (MS) or an access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device such as a digital camera, a game terminal device, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a notebook embedded device (LEE), a laptop mounted device (LME), a USB dongle, a smart device, a wireless user equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automated processing chain), consumer electronic devices, relay nodes, devices operating on commercial and / or industrial wireless networks, etc. The mobile terminal (MT) part of the IAB node can perform the functions of a "terminal device" and can therefore operate as a terminal device. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" can be used interchangeably.

[0022] Although the functions described herein may be performed in fixed and / or wireless network nodes in various exemplary embodiments, in other exemplary embodiments, the functions may be implemented in a user equipment device (such as a cellular phone, or a tablet computer, or a laptop computer, or a desktop computer, or a mobile Internet of Things device, or a fixed Internet of Things device). For example, the user equipment device may appropriately have the corresponding capabilities described in relation to fixed and / or wireless network nodes. The user equipment device may be a user device and / or a control device, such as a chipset or a processor, which is configured to control the user device when the user device is installed therein. Examples of these functions include boot server functions and / or home user servers, which may be implemented in a user equipment device by providing the user equipment device with software configured to cause the user equipment device to execute from the perspective of these functions / nodes.

[0023] The following first introduces the knowledge related to the technical solution of the present disclosure and the technical concept of the present disclosure.

[0024] Communication satellites are artificial earth satellites used as radio communication relay stations in space. They are the space part of the satellite communication system, used to forward or process radio communication signals to achieve communication between earth stations (including handheld terminals) or between spacecraft and earth stations. Navigation satellites are artificial satellites used to provide wireless navigation signals and navigation information, providing users with navigation, positioning and timing services. The navigation satellite system has high positioning accuracy and a wide service range, and can provide all-day, all-weather, continuous navigation and positioning services.

[0025] In recent years, as users have increasingly demanded wider coverage, higher efficiency, and higher precision, the integration of communication and navigation has become an important direction. This communication and navigation integration system requires the integration of the entire satellite's time and frequency, but communication and navigation have different requirements for time and frequency. High-precision satellite-to-ground broadband communication requires that the deviation between the satellite's 1PPS (Pulse Per Second) and the ground time be within ±50ns (nanoseconds), and there is no requirement for the stability of 1PPS. However, the navigation-enhanced 1PPS requires that it be as stable as possible, and the deviation from the ground time within ±1ms (milliseconds) is acceptable. This results in the traditional communication time synchronization mechanism based on GNSS (Global Navigation Satellite System) or the navigation time synchronization mechanism based on atomic clocks that are not adjusted for a long time, which cannot meet the requirements for the unification of communication and navigation signal time and frequency under the communication and navigation integration system.

[0026] In practical applications, the frequency of low-orbit satellites can be generated by a small rubidium clock or a high-stability crystal oscillator. Based on the measurement results of the initial frequency accuracy, the initial frequency of the satellite is calibrated to adjust the satellite frequency accuracy to 10 -13 The ground measurement and control system can use the measurement results of the satellite-ground clock difference as a basis to test the satellite's time-frequency-phase function by sending control instructions and phase adjustment parameters.

[0027] The function of the satellite time and frequency reference can be verified by sending control instructions and phase adjustment parameters through the ground system to verify the frequency and phase modulation functions. The autonomous small-step frequency modulation function of the satellite time and frequency reference can be understood as the clock system on the satellite can autonomously make small frequency adjustments based on the deviation of its own time and frequency reference to maintain time synchronization and frequency stability. Traditional test methods can only perform simple frequency modulation or phase modulation functions, and do not have the ability to verify the autonomous small-step frequency modulation function of the satellite time and frequency reference in a closed loop.

[0028] Figure 2 FIG. 200 shows a flow chart of a satellite time and frequency reference small step frequency modulation service function in an embodiment of the present disclosure. For example, referring to Figure 2As shown, in the process of small-step frequency modulation of satellite time and frequency reference, small-step frequency modulation control data analysis is performed in step S210; small-step frequency modulation service data analysis is performed in step S220; satellite-to-ground clock difference is output in step S221; frequency adjustment amount is output in step S222; parameters are configured in step S230; existing information is converted into frequency and phase adjustment parameters in step S240; digital phase adjustment is performed in step S250; digital frequency adjustment is performed in step S260; and oven controlled crystal oscillator (OCXO) is controlled and output in step S270.

[0029] The present disclosure takes into account the need to better verify the ability of the satellite time and frequency reference autonomous small-step frequency modulation function, and therefore proposes a test method for the satellite time and frequency reference small-step frequency modulation function. The test method generates a small-step frequency modulation strategy based on the clock deviation information between the reference clock of the test end (such as the ground test system) and the initial clock information of the measured satellite, and continuously adjusts the clock frequency of the measured satellite, and the frequency adjustment amplitude each time is less than or equal to the first threshold, which effectively avoids the impact of large frequency adjustments on the stability of the satellite system; by combining the ranging information between the test end and the measured satellite, the impact of the continuous adjustment process on the ranging accuracy can be determined. The present disclosure can provide reliable testing support for small-step frequency modulation functions for applications such as satellite navigation and communications.

[0030] The present disclosure is equivalent to a test method for autonomously performing small-step frequency modulation of a time-frequency reference by a communication and navigation fusion satellite, which can realize closed-loop verification of the performance of the satellite time-frequency reference autonomous small-step frequency modulation function. The test method can be used as a method for testing satellite time-frequency reference signals. For example, by injecting a telegram containing satellite-to-ground clock difference information into a satellite through a ground test system, a refined test of small-step frequency modulation can be realized, and the stepping of the satellite autonomous small-step frequency modulation can be verified with an accuracy of up to 10 -12 The test method disclosed in the present invention can verify the influence of satellite small-step frequency modulation on various communication payloads and navigation payloads, and is applicable to the function and performance test and verification of other communication and navigation fusion systems.

[0031] Here, the test system of the satellite time and frequency reference small step frequency modulation function designed by the present disclosure for implementing the test method of the satellite time and frequency reference small step frequency modulation function is first introduced, so as to facilitate the understanding of the test method introduced later. The test system is equivalent to the system test environment.

[0032] The test system disclosed in the present invention includes an onboard test system and a ground test system. The onboard test system is arranged on the satellite under test, and is used to provide data and information required by the test method; the ground test system is arranged on the test end, and the test end is equivalent to the ground system, and the ground test system is used to provide data and information required by the test method. The satellite under test disclosed in the present invention can operate in a satellite autonomous control mode or a ground control mode, and the components of the test system corresponding to these two control modes are different.

[0033] Figure 3 A schematic diagram 300 of a test system for satellite time and frequency reference small-step frequency modulation in a satellite autonomous control mode in an embodiment of the present disclosure is shown. Figure 3 As shown, the test system includes components of the onboard test system and the ground test system. The onboard test system in the test system includes: a navigation enhancement processor 380, a communication payload 390, and a satellite-borne rubidium clock 370. The ground test system includes: a navigation data processing system 310, a time interval frequency counter (such as SR620), a ground test hydrogen clock 320, a communication network simulator 330, a phase comparator 340 (such as a PICOTIME phase comparator), a navigation enhancement ground terminal 350, and a ground communication terminal 360.

[0034] Figure 4 A schematic diagram 400 of a test system for satellite time and frequency reference small-step frequency modulation in ground control mode in an embodiment of the present disclosure is shown. Figure 4 As shown, the test system includes components of the on-board test system and the ground test system. The on-board test system in the test system includes: a navigation enhancement processor 380, a communication payload 390, a satellite-borne rubidium clock 370, and a satellite-borne timing receiver 3110. The ground test system includes: a navigation data processing system 310, a communication network simulator 330, a navigation enhancement ground terminal 350, and a ground communication terminal 360.

[0035] For example, in practical applications, the components of the test system can be freely set as needed. In some embodiments, the onboard test system set on the satellite under test includes: one or any combination of a navigation enhancement processor 380, a communication payload 390, a satellite-borne rubidium clock 370, and a satellite-borne timing receiver 3110; the ground test system at the test end includes: one or any combination of a navigation data processing system 310, a time interval frequency counter (such as SR620), a ground test hydrogen clock 320, a communication network simulator 330, a phase comparator 340 (such as a PICOTIME phase comparator), a navigation enhancement ground terminal 350, and a ground communication terminal 360.

[0036] Exemplarily, the navigation enhancement processor 380 can be used as the device under test. The capabilities of the navigation data processing system 310 include: the capability of measuring and reading the time difference and generating messages, and the capability of fitting the satellite-ground relative frequency difference according to the measurement results.

[0037] In some embodiments, in the onboard test system, the functions of the components are as follows: The onboard rubidium clock 370 is used to set the initial clock information of the satellite under test, and the initial clock information includes the initial time and the initial frequency.

[0038] The satellite-borne timing receiver 3110 is used to receive the annotation message transmitted by the test end, and the annotation message includes the clock deviation information between the reference clock of the test end and the initial clock information.

[0039] The navigation enhancement processor 380 is used to generate a clock frequency adjustment strategy based on the clock deviation information and the satellite equipment delay difference parameter, and continuously adjust the clock frequency of the measured satellite according to the clock frequency adjustment strategy.

[0040] The communication payload 390 is used to generate ranging information between the test end and the satellite under test during the continuous adjustment process.

[0041] In some embodiments, in the ground test system, the functions of each component are as follows: The ground test hydrogen clock 320 is used to generate a reference clock for the test end.

[0042] The navigation data processing system 310 is used to calculate the clock deviation information between the reference clock and the initial clock information of the measured satellite in real time, and to generate the clock frequency adjustment strategy and adjustment instruction of the measured satellite according to the clock deviation information and the small-step frequency modulation strategy.

[0043] The communication network simulator 330 is used to inject the clock frequency adjustment strategy and adjustment instructions into the satellite under test.

[0044] The time interval frequency counter is used to measure the time difference between the time of the measured satellite and the reference clock.

[0045] The phase comparator 340 is used to measure the frequency difference between the frequency of the satellite under test and the reference clock.

[0046] The navigation enhancement ground terminal 350 and the ground communication terminal 360 are used to generate ranging information between the test end and the measured satellite during the continuous adjustment process.

[0047] Exemplarily, when the satellite-to-ground clock difference and the drift value of the satellite-to-ground clock difference exceed a threshold, the satellite frequency can be adjusted. The satellite frequency adjustment amount and adjustment frequency can be in two modes, namely, ground control mode and satellite autonomous control mode. Exemplarily: (1) When the frequency adjustment method is in ground control mode, the ground can inject frequency modulation parameters into the satellite, and the satellite adjusts its own frequency according to the frequency modulation parameters injected by the ground. (2) When the frequency adjustment method is in satellite autonomous control mode, the ground can inject the calculated satellite-to-ground clock difference into the satellite, and the satellite executes the satellite-to-ground time synchronization method for communication and navigation fusion according to the satellite-to-ground clock difference measurement result injected by the ground.

[0048] Taking into account that the satellite can operate in satellite autonomous control mode or ground control mode, the test method disclosed in the present invention can be divided into two modes, Class A and Class B. It can be considered that the Class A test method corresponds to the test of satellite autonomous small-step frequency modulation (i.e. satellite autonomous control mode), and the Class B test method corresponds to the test of ground control small-step frequency modulation (i.e. ground control mode).

[0049] The following will refer to Figure 1 The principles and implementations of the present disclosure are described in detail.

[0050] Figure 1 A flowchart 100 is shown of a method for testing a satellite time and frequency reference small-step frequency modulation function according to an embodiment of the present disclosure. Figure 1 As shown, the test method of the satellite time and frequency reference small step frequency modulation function of this embodiment includes the following steps: Step S1: setting the initial clock information of the satellite under test, the initial clock information including the initial time and the initial frequency; Step S2: obtaining a clock frequency adjustment strategy of the satellite under test according to the clock deviation information between the reference clock of the test end and the initial clock information; Step S3: continuously adjusting the clock frequency of the satellite under test according to the clock frequency adjustment strategy; wherein the frequency adjustment amplitude of the clock each time is less than or equal to the first threshold; Step S4: During the continuous adjustment process, the test of the satellite under test is completed according to the ranging information between the test terminal and the satellite under test.

[0051] For example, the difference between the satellite autonomous control mode and the ground control mode is mainly in step S2. The above steps S1 to S4 will be described in detail below: In step S1, the initial clock information of the satellite under test is set, and the initial clock information includes the initial time and the initial frequency. Exemplarily, after the satellite under test (i.e., the satellite payload) is started, the initial clock information of the satellite under test can be set. For example, the ground test end sends a command to the measurement, control and operation control link to start the satellite under test, and monitors the operating status of the satellite under test according to the telemetry signal; wherein the telemetry signal includes one or any combination of voltage, temperature, and lock indication.

[0052] refer to Figure 3 and Figure 4 As shown, in some embodiments, the clock of the satellite under test includes an onboard rubidium clock 370 .

[0053] In step S2, the clock frequency adjustment strategy of the satellite under test is obtained according to the clock deviation information between the reference clock of the test end and the initial clock information. Figure 3 As shown, in some embodiments, the reference clock includes a ground hydrogen clock (ie, a ground test hydrogen clock 320 ).

[0054] In some embodiments, the time deviation between the initial time and the reference clock is less than or equal to a second threshold. The second threshold includes: 20ns, where ns represents nanoseconds. Exemplarily, the satellite-to-ground clock difference can be obtained by calculating the time difference between the ground test terminal and the satellite under test, and the satellite-to-ground clock difference can be adjusted to be less than or equal to a second threshold (such as ±20ns). The second threshold can be -20ns, -10ns, 0ns, +10ns, +20ns, etc. The present disclosure can improve the time synchronization accuracy of the satellite time-frequency reference and reduce the impact of the time deviation on the ranging and navigation performance by making the time deviation between the initial time and the reference clock less than or equal to the second threshold.

[0055] In some embodiments, the frequency deviation between the initial frequency and the reference clock is less than or equal to a third threshold. The third threshold includes: -13 For example, the frequency deviation between the ground test terminal and the satellite under test can be calculated to obtain the relative frequency difference of the atomic clock, and the relative frequency difference of the atomic clock can be adjusted to be less than or equal to the third threshold value (such as 10 -13 ). The present disclosure can improve the frequency stability and synchronization accuracy of the satellite time-frequency reference by making the frequency deviation between the initial frequency and the reference clock less than or equal to the third threshold, thereby reducing the impact of the frequency deviation on satellite navigation.

[0056] In some embodiments, in the satellite autonomous control mode, obtaining a clock frequency adjustment strategy of the satellite under test according to clock deviation information between a reference clock of the test end and initial clock information includes: The satellite under test receives the annotation message transmitted by the test end, and the annotation message includes clock deviation information; The satellite under test generates a clock frequency adjustment strategy based on the clock deviation information and satellite equipment delay difference parameters.

[0057] Exemplarily, the measured satellite parses the telegram to obtain clock deviation information. The satellite equipment delay difference parameter refers to the delay of the navigation enhancement transmission signal channel. Since the clock error result of the low-orbit satellite is mainly obtained through the GNSS monitoring receiver, and the satellite-to-ground clock error does not include the delay of each transmission channel, when realizing high-precision navigation enhancement, it is necessary to add the satellite-to-ground clock error to the delay of the transmission channel as the clock error of the downlink transmission signal.

[0058] Exemplarily, the ground test end can inject a telegram containing satellite-ground clock difference information into the satellite under test. After parsing the clock difference information, the satellite under test will autonomously generate a small-step frequency modulation strategy and perform small-step frequency modulation operations, thereby smoothly adjusting its time and frequency reference. This process can control the deviation between satellite time and ground time within ±50ns, while ensuring that the normal operation of communication service functions is not affected. The present disclosure can verify the satellite's autonomous clock difference prediction and the satellite's autonomous control of small-step frequency modulation capabilities, achieving a full closed-loop verification of the satellite's small-step frequency modulation function, thereby improving the efficiency of system testing.

[0059] In some embodiments, in the ground control mode, obtaining a clock frequency adjustment strategy of the satellite under test according to clock deviation information between a reference clock of the test end and initial clock information includes: The test end calculates the clock deviation information in real time, and generates the clock frequency adjustment strategy and adjustment instructions based on the clock deviation information and the small-step frequency adjustment strategy; The test end injects the clock frequency adjustment strategy and adjustment instructions to the satellite under test.

[0060] Exemplarily, the ground test end can generate a frequency adjustment instruction based on the relative frequency difference of the atomic clock and the small-step frequency modulation strategy; wherein the frequency adjustment instruction includes the frequency adjustment amount and the frequency adjustment frequency. The ground test end injects the frequency adjustment instruction to the satellite under test. Subsequently, the satellite under test executes the frequency adjustment instruction to synchronize the satellite and ground time, and telemeters to determine the execution status of the frequency adjustment instruction. The present disclosure can ensure high-precision time synchronization, and verify the execution effect through telemetry, thereby enhancing the reliability of the small-step frequency modulation function, and can provide a stable and accurate time reference for satellite navigation, communication and other applications.

[0061] In step S3, the clock frequency of the satellite under test is continuously adjusted according to the clock frequency adjustment strategy; wherein the frequency adjustment amplitude of the clock each time is less than or equal to the first threshold. For example, when the satellite under test continuously adjusts the clock frequency, the first threshold of the frequency adjustment amplitude each time can be 10 -11 Hz or 10 -5 Hz.

[0062] In step S4, during the continuous adjustment process, the test of the satellite under test is completed according to the ranging information between the test terminal and the satellite under test. In some embodiments, before completing the test of the satellite under test, it also includes: Calculate a first mean and / or a first standard deviation of the ranging information before continuous adjustment; Calculating a second mean and / or a second standard deviation of the ranging information during the continuous adjustment process; In response to a difference between the first mean and the second mean being greater than a first preset difference, and / or in response to a difference between the first standard deviation and the second standard deviation being greater than a second preset difference; It is determined that the continuous adjustment process has an impact on the ranging accuracy.

[0063] For example, in order to determine the impact of small-step frequency modulation on the ranging accuracy of the communication payload terminal, monitoring is required. By observing the changes in the ranging information of the navigation augmentation ground terminal, it is possible to evaluate whether the small-step frequency modulation has an impact on the operation of the navigation augmentation processor, and then determine whether the small-step frequency modulation meets the time-frequency requirements of the communication navigation payload. If the mean and standard deviation of the ranging information do not change before and after the small-step frequency modulation, it can be considered that the small-step frequency modulation has no impact on the ranging accuracy. On the contrary, if the mean changes and the standard deviation increases by more than 0.1ns, it can be considered to have an impact.

[0064] By quantitatively analyzing the changes in ranging data before and after frequency modulation, the present invention can accurately identify whether the small-step frequency modulation operation introduces ranging errors, thereby providing an intuitive and accurate basis for evaluating and optimizing the performance of satellite time and frequency systems, and helping to further improve the ranging accuracy and reliability of satellites in navigation, communication and other services.

[0065] Below is a specific embodiment, referring to Figure 3 The Class A test method mentioned above is introduced in combination with the on-board test system and the ground test system. The Class A test method corresponds to the test of satellite autonomous small-step frequency modulation (i.e., satellite autonomous control mode).

[0066] (a1) Send instructions to the TT&C link through the communication network simulator to turn on the satellite under test and determine the basic health status of the start-up payload based on telemetry signals such as voltage, temperature, and lock indication; (a2) Measure the time difference between the ground time and the navigation augmentation processor, i.e. the phase difference of the 1PPS signal, through SR620 (time interval frequency counter); (a3) The communication network simulator sends a time synchronization command or a phase adjustment command to adjust the satellite-to-ground time deviation (i.e., satellite-to-ground clock difference) a0 to within ±20ns; (a4) Measure the frequency difference between the satellite clock and the ground test hydrogen clock using the PICOTIME phase comparator; (a5) According to the frequency difference value measured by the PICOTIME phase comparator, the communication network simulator sends a frequency modulation command through the ground control channel to adjust the relative frequency difference a1 between the satellite and the ground atomic clock to 10 -13 the following; (a6) The navigation data processing system automatically reads the measurement results of SR620 and updates the satellite-to-earth clock error a0 in the above message every 10 seconds based on the measurement results; (a7) The communication network simulator sends the message containing the satellite-to-ground clock error a0 generated by the navigation data processing system to the navigation augmentation processor through the ground operation and control channel; (a8) The navigation augmentation processor formulates a frequency modulation strategy based on the low-orbit satellite clock error results recorded on the ground and the satellite equipment delay difference parameters, and autonomously implements small-step frequency modulation of the satellite. The frequency adjustment amount each time does not exceed 10 -11 Hz (Hertz) or 10 - 5 Hz; (a9) The relative deviation of 1PPS between the satellite and the ground test hydrogen clock is monitored by SR620, and the relative frequency difference between the satellite and the ground clock is monitored by PICOTIME phase comparison instrument; (a10) Whether the ranging value of the observation navigation augmentation ground terminal and the ground communication terminal affects the ranging accuracy during the small-step frequency modulation process.

[0067] For example, the Class A test method disclosed in the present invention uses a ground-based hydrogen atomic clock to ensure the high stability of the ground-based time and frequency system, ensuring that the rapid change of the satellite-ground frequency deviation will not be caused by the instability of the ground-based time and frequency system. Before starting the small-step frequency modulation, it is necessary to send a phase modulation command to adjust the satellite-ground clock difference to within ±20ns, and it is necessary to send a frequency modulation command to adjust the satellite-ground frequency difference to 10 -13 SR620 is used to verify the change of satellite-ground clock difference in the small-step frequency modulation process in a closed loop, and the ground operation and control system updates the message after the satellite-ground clock difference measurement results every 10 seconds. The satellite autonomously generates and executes the small-step frequency modulation strategy based on the clock difference measurement results in the message uploaded by the ground. PICROTIME is used to verify the change of satellite-ground frequency in the small-step frequency modulation process in a closed loop. During the small-step frequency modulation process, the ranging values ​​of the navigation enhancement ground terminal and the ground communication terminal are observed in real time to determine whether the ranging accuracy is affected during the small-step frequency modulation process.

[0068] Below is a specific embodiment, referring to Figure 4 The above-mentioned Type B test method is introduced in combination with the on-board test system and the ground test system. The Type B test method corresponds to the test of small-step frequency modulation of ground control (ie, ground control mode).

[0069] (b1) Sending commands through the communication network simulator to turn on the satellite under test, and judging the basic health status of the powered-on payload based on telemetry signals such as voltage, temperature, and lock indication; (b2) The navigation data processing system determines the satellite-to-earth clock error and frequency deviation through the measurement results of the onboard timing receiver and the ranging results of rapid and precise positioning; (b3) Based on the measurement results of the satellite-to-earth clock error, the communication network simulator sends a phase adjustment command to adjust the satellite-to-earth clock error to within ±20ns; (b4) Based on the measured frequency deviation, the communication network simulator sends a frequency modulation command to adjust the frequency difference between the satellite and the ground atomic clock to 10 -13 the following; (b5) The navigation data processing system calculates the clock error and frequency deviation measurement results in real time, and then formulates the frequency adjustment amount and adjustment frequency based on the frequency deviation results and the small-step frequency modulation strategy; (b6) the communication network simulator sends the frequency adjustment command generated by the navigation data processing system to the navigation enhancement processor; (b7) The satellite's navigation augmentation processor executes the frequency adjustment command sent from the ground and determines the execution of the command based on the received command count and the frequency adjustment value telemetry; (b8) Whether the ranging value of the observation navigation augmentation ground terminal and the ground communication terminal affects the ranging accuracy during the small-step frequency modulation process.

[0070] For example, the present disclosure can ensure the high stability of the ground time and frequency system through the ground hydrogen atomic clock, ensuring that the rapid change of the satellite-ground frequency deviation will not be caused by the instability of the ground time and frequency system. Before starting the small-step frequency modulation, it is necessary to send a phase modulation command to adjust the satellite-ground clock difference to within ±20ns, and it is necessary to send a frequency modulation command to adjust the satellite-ground frequency difference to 10 -13 The navigation data processing system uses the satellite-to-ground ranging value to calculate the satellite-to-ground clock error and frequency deviation. The navigation enhancement processor executes the frequency adjustment command on the ground and determines the execution of the command based on the received command count and the frequency adjustment value telemetry. The ranging value of the navigation enhancement ground terminal and the ground communication terminal is observed to determine whether the ranging accuracy is affected during the small-step frequency modulation process.

[0071] The basis for determining the small-step frequency modulation test results disclosed in the present invention is summarized here.

[0072] For example, the satellite can adjust the phase of the satellite 1PPS signal according to the satellite-to-ground clock difference injected from the ground to achieve a small-step frequency modulation function. The determination basis of the small-step frequency modulation function is: (1) The satellite-to-ground clock error can be controlled within ±50ns; (2) Each frequency adjustment can be within 10 -5 Below Hz; (3) The accuracy of the distance measurement value of the communication payload terminal is not affected by the small-step frequency modulation, and it is necessary to determine its impact. By monitoring the changes in the distance measurement value of the navigation augmentation ground terminal, it can be determined whether the small-step frequency modulation has an impact on the operation of the navigation augmentation processor, thereby determining whether the small-step frequency modulation can meet the time and frequency requirements of the communication navigation payload.

[0073] Generally, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are shown and described as block diagrams, flow charts, or using some other graphical representations, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof.

[0074] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer executable instructions, such as instructions included in program modules, which are executed in a device on a target real or virtual processor to perform the above-mentioned reference Figure 1 The test method described. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of the program modules can be combined or separated between program modules as needed. Machine executable instructions for program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0075] The program code for executing the disclosed method can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing equipment so that when the program code is executed by the processor or controller, the function / operation specified in the flow chart and / or block diagram is realized. The program code can be executed completely on the machine as an independent software package, partially on the machine, partially on the machine, partially on a remote machine, partially on a remote machine, or all on a remote machine or server.

[0076] In the context of the present disclosure, computer program codes or related data may be carried by any appropriate carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0077] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or apparatuses, or any suitable combination of the foregoing. More specific examples of computer readable storage media include an electrical connection having one or more conductors, a portable computer floppy disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0078] In addition, although the operations are described in a specific order, this should not be understood as requiring the specific order or sequence shown to be performed, or performing all the operations shown, to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these details should not be interpreted as limitations on the scope of the present disclosure, but can be interpreted as descriptions of features specific to a particular embodiment. Certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0079] Although the disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method for testing the small-step frequency modulation function of a satellite time and frequency reference, characterized in that: include: Setting initial clock information of the satellite under test, wherein the initial clock information includes an initial time and an initial frequency; Obtaining a clock frequency adjustment strategy for the satellite under test according to clock deviation information between a reference clock of the test end and the initial clock information; Continuously adjusting the clock frequency of the satellite under test according to the clock frequency adjustment strategy; wherein each frequency adjustment amplitude of the clock is less than or equal to a first threshold; During the continuous adjustment process, the test of the satellite under test is completed according to the ranging information between the test end and the satellite under test.

2. The testing method according to claim 1, characterized in that: Obtaining a clock frequency adjustment strategy for the satellite under test according to clock deviation information between a reference clock of the test end and the initial clock information, including: The satellite under test receives an annotation message transmitted by the test end, wherein the annotation message includes the clock deviation information; The measured satellite generates the clock frequency adjustment strategy according to the clock deviation information and the satellite equipment delay difference parameter.

3. The testing method according to claim 1, characterized in that: Obtaining a clock frequency adjustment strategy for the satellite under test according to clock deviation information between a reference clock of the test end and the initial clock information, including: The test end calculates the clock deviation information in real time, and generates the clock frequency adjustment strategy and adjustment instruction according to the clock deviation information and the small-step frequency adjustment strategy; The test end injects the clock frequency adjustment strategy and the adjustment instruction to the satellite under test.

4. The testing method according to claim 1, characterized in that: Before completing the test of the satellite under test, the method further includes: Calculating a first mean value and / or a first standard deviation of the ranging information before the continuous adjustment; Calculating a second mean value and / or a second standard deviation of the ranging information during the continuous adjustment process; In response to a difference between the first mean and the second mean being greater than a first preset difference, and / or in response to a difference between the first standard deviation and the second standard deviation being greater than a second preset difference; It is determined that the continuous adjustment process has an impact on the distance measurement accuracy.

5. The testing method according to claim 1, characterized in that: The time deviation between the initial time and the reference clock is less than or equal to a second threshold; the frequency deviation between the initial frequency and the reference clock is less than or equal to a third threshold.

6. The testing method according to any one of claims 1 to 5, characterized in that: The clock of the satellite under test includes a satellite-borne rubidium clock.

7. The testing method according to any one of claims 1 to 5, characterized in that: The reference clock includes a ground-based hydrogen clock.

8. The testing method according to claim 5, characterized in that: The second threshold includes: 20ns, where ns represents nanoseconds.

9. The testing method according to claim 5, characterized in that: The third threshold includes: 10 -13 .

10. The testing method according to any one of claims 1 to 5, characterized in that: The measured satellite is provided with: a navigation enhancement processor, a communication payload, a satellite-borne rubidium clock, a satellite-borne timing receiver, or any combination thereof; The test end includes: a navigation data processing system, a time interval frequency counter, a ground test hydrogen clock, a communication network simulator, a phase comparator, a navigation enhancement ground terminal, and a ground communication terminal, or any combination thereof.

11. An on-board test system for the small-step frequency modulation function of a satellite time and frequency reference, characterized in that: Used for a satellite under test to implement the test method as described in any one of claims 1 to 9, comprising: A satellite-borne rubidium clock, used to set initial clock information of the satellite under test, wherein the initial clock information includes an initial time and an initial frequency; A satellite-borne timing receiver, used for receiving an annotation message transmitted by a test end, wherein the annotation message includes clock deviation information between a reference clock of the test end and the initial clock information; A navigation enhancement processor, configured to generate a clock frequency adjustment strategy according to the clock deviation information and the satellite device delay difference parameter, and continuously adjust the clock frequency of the measured satellite according to the clock frequency adjustment strategy; The communication payload is used to generate ranging information between the test end and the measured satellite during the continuous adjustment process.

12. A ground test system for the small-step frequency modulation function of a satellite time and frequency reference, characterized in that: Used in a test terminal to implement the test method according to any one of claims 1 to 9, comprising: A ground test hydrogen clock, used to generate a reference clock of the test end; A navigation data processing system, used for calculating in real time the clock deviation information between the reference clock and the initial clock information of the measured satellite, and generating a clock frequency adjustment strategy and adjustment instructions of the measured satellite according to the clock deviation information and the small-step frequency modulation strategy; A communication network simulator, used for injecting the clock frequency adjustment strategy and the adjustment instruction into the satellite under test; A time interval frequency counter, used for measuring the time difference between the time of the measured satellite and the reference clock; A phase comparator, used for measuring the frequency difference between the frequency of the satellite under test and the reference clock; The navigation enhancement ground terminal and the ground communication terminal are used to generate ranging information between the test end and the measured satellite during the continuous adjustment process.

13. A test system for the small-step frequency modulation function of a satellite time and frequency reference, characterized in that: It comprises the on-board test system as claimed in claim 11 and the ground test system as claimed in claim 12.

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