Test dynamic simulation method and system for TT&C transponder

Abstract

This application relates to the field of wireless communication technology and provides a dynamic simulation method and system for testing a telemetry and control transponder. The dynamic simulation method includes: dynamically modulating each uplink baseband signal using Doppler frequency based on uplink frequency parameters and a simulated motion trajectory to obtain an uplink test simulation signal, which is then output to the telemetry and control transponder for uplink testing; demodulating the downlink static signal received from the telemetry and control transponder to obtain downlink measurement data corresponding to the downlink static signal, and performing dynamic Doppler simulation on the downlink measurement data in the information domain to obtain a simulated downlink measurement result, which is then output to the telemetry and control transponder, enabling the transponder to parse the downlink measurement result for testing. This dynamic simulation method enables integrated dynamic simulation testing of uplink and downlink, realistically reproducing channel changes caused by aircraft motion, thereby improving test reliability.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a test dynamic simulation method and system for a telemetry and control transponder. Background Technology

[0002] In aerospace telemetry and control systems, the onboard telemetry and control transponder is the core equipment for realizing space-to-ground communication. It undertakes key functions such as ground remote control, ranging signal reception and telemetry, and ranging signal downlink. Its transceiver performance directly determines the reliability of the space-to-ground link, so it is necessary to conduct simulation tests on the ground.

[0003] Traditional telemetry and control transponder testing methods often use test signals with fixed Doppler frequencies for verification, which do not fully consider the characteristics of real working scenarios and cannot reproduce the dynamic channel changes caused by the movement of the aircraft. This results in a large difference between the test scenario and the on-orbit operating conditions of the telemetry and control transponder, leading to insufficient reliability of the test results. Summary of the Invention

[0004] In view of this, this application aims to propose a dynamic simulation method for testing transponders to improve the reliability of test results.

[0005] To achieve the above objectives, the technical solution of this application is implemented as follows: A dynamic simulation method for testing a telemetry and control transponder, comprising: Acquire the uplink baseband signals used for simulation testing, as well as the uplink frequency parameters and the simulated motion trajectory of the telemetry and control transponder; Based on the uplink frequency parameters and the simulated motion trajectory, Doppler frequency dynamic modulation is performed on each of the uplink baseband signals to obtain an uplink test simulation signal, which is then output to the telemetry and control transponder, enabling the telemetry and control transponder to perform uplink tests based on the uplink test simulation signal. The downlink measurement data corresponding to the downlink static signal is obtained by demodulation from the downlink static signal sent by the received telemetry and control transponder; The downlink measurement data is subjected to dynamic Doppler simulation in the information domain to obtain simulated downlink measurement results, and the downlink measurement results are output to the telemetry and control transponder, so that the telemetry and control transponder can parse the downlink measurement results for testing.

[0006] Furthermore, based on the uplink frequency parameters and the simulated motion trajectory, the uplink baseband signals are subjected to Doppler frequency dynamic modulation to obtain uplink test simulated signals, including: Based on the uplink frequency parameters and the simulated motion trajectory, calculate the dynamically changing Doppler frequency in the ground-to-ground transmission link due to the movement of the telemetry and control transponder; Based on the Doppler frequency, each of the uplink baseband signals is modulated; The modulated uplink baseband signals are upconverted and combined to obtain radio frequency uplink test simulation signals, which are then sent to the telemetry and control transponder so that the telemetry and control transponder performs tests based on the uplink test simulation signals.

[0007] Furthermore, the calculation of the dynamically changing Doppler frequency in the ground-to-ground transmission link due to the movement of the telemetry and control transponder includes: A discrete sampling point is taken at preset time intervals in the simulated motion trajectory; Based on the simulated motion trajectory, calculate the Doppler frequency and the rate of change of Doppler frequency corresponding to each discrete sampling point; Based on the Doppler frequency and Doppler frequency change rate corresponding to each discrete sampling point, linear interpolation is performed between two adjacent discrete sampling points to obtain each intermediate point and the Doppler frequency corresponding to each intermediate point.

[0008] Furthermore, the uplink frequency parameters include the uplink carrier frequency and the spreading code rate; The modulation processing of each of the uplink baseband signals includes: Based on the uplink carrier frequency, the spreading code rate, and the Doppler frequency corresponding to each time moment, calculate the pseudocode Doppler frequency at each time moment; Calculate the phase of the pseudocode sequence at each time step based on the pseudocode Doppler frequency at each time step; Based on the phase of the pseudocode sequence, the pseudocode sequence is determined; Based on the preset carrier frequency and the Doppler frequency corresponding to each time moment, a carrier signal with dynamic Doppler is determined; The uplink baseband signal is modulated based on the carrier signal and the pseudocode sequence.

[0009] Furthermore, the phase of the pseudocode sequence is calculated using the following formula: ; ; in, The phase of the pseudocode sequence, Let C be the initial pseudocode phase and C be the speed of light. The initial distance for the telemetry and control transponder. The spreading code rate is... This is the pseudocode Doppler frequency.

[0010] Furthermore, the modulation processing of the uplink baseband signal based on the carrier signal and the pseudocode sequence includes: Determine the uplink information data frame carried by the uplink baseband signal; The uplink information data frame is subjected to direct sequence spread spectrum modulation processing using the pseudocode sequence to obtain the spread spectrum modulated uplink baseband signal. Using the carrier signal, the spread spectrum modulated uplink baseband signal is subjected to carrier modulation processing to obtain the modulated uplink baseband signal.

[0011] Furthermore, the uplink baseband signal includes an uplink measurement baseband signal and an uplink remote control baseband signal; The step of upconverting and combining the modulated uplink baseband signals to obtain the radio frequency uplink test simulation signal includes: The modulated uplink measurement baseband signal and the modulated uplink remote control baseband signal are respectively subjected to pulse shaping processing to obtain a first digital intermediate frequency sequence and a second digital intermediate frequency sequence; The first digital intermediate frequency sequence and the second digital intermediate frequency sequence are linearly superimposed and combined to obtain a composite data intermediate frequency signal. The composite data intermediate frequency signal is converted from digital to analog to obtain an analog intermediate frequency signal; The simulated intermediate frequency signal is mixed with a preset radio frequency local oscillator signal to obtain the uplink test simulated signal of the radio frequency.

[0012] Furthermore, the step of demodulating the downlink measurement data corresponding to the downlink static signal received from the telemetry and control transponder includes: Receive the downlink static signal sent by the telemetry and control transponder; A down-conversion local oscillator signal is generated based on a preset down-frequency radio frequency local oscillator frequency; The down-conversion local oscillator signal and the down-current static signal are input to a mixer for mixing to obtain a mixed signal; The mixed signal is filtered to retain the intermediate frequency difference frequency component, thus obtaining the intermediate frequency difference frequency signal. Demodulate the intermediate frequency difference signal to obtain downlink valid data, as well as the static code phase and the corresponding static carrier Doppler frequency of the downlink static signal; The downlink measurement data includes the static code phase corresponding to the downlink static signal and the corresponding static carrier Doppler frequency.

[0013] Furthermore, the step of performing dynamic Doppler simulation on the downlink measurement data in the information domain to obtain the simulated downlink measurement results includes: Based on the simulated motion trajectory, the downlink theoretical dynamic delay and downlink theoretical dynamic Doppler frequency corresponding to the downlink transmission link are calculated using a preset trajectory model. The downlink theoretical dynamic delay is superimposed on the static code phase, and the downlink theoretical dynamic Doppler frequency is superimposed on the static carrier Doppler frequency to obtain the simulated downlink measurement result.

[0014] Compared with related technologies, this application has at least the following advantages: The test dynamic simulation method for the telemetry and control transponder described in this application uses simulated motion trajectory and uplink frequency parameters to simulate the dynamically changing Doppler frequency in the space-to-ground transmission link due to the movement of the aircraft. After performing Doppler frequency dynamic modulation processing on each uplink baseband signal, an uplink test simulation signal is obtained, and the telemetry and control transponder analyzes the uplink test simulation signal to perform uplink testing.

[0015] By simulating the motion trajectory to generate uplink test simulation signals that closely resemble the actual ground-to-ground transmission link, the channel changes caused by the aircraft's motion in the uplink transmission link can be accurately reproduced, thereby improving the reliability of the test.

[0016] Furthermore, this application can simulate and test not only the uplink transmission link but also the downlink transmission link, achieving integrated simulation and testing of both. On one hand, this application employs a static transmission method in the downlink transmission link, receiving a static downlink signal instead of dynamically simulating it using hardware simulation links. This avoids problems such as quantization noise, phase jitter, increased hardware costs, and increased system latency introduced by the RF sampling and regeneration architecture in hardware simulation links, thereby ensuring a high signal-to-noise ratio and high stability in the downlink signal receiving channel.

[0017] On the other hand, after receiving the downlink static signal, dynamic simulation is then performed in the information domain. That is, in the simulation test of the downlink transmission link, the dynamic simulation is not performed in the signal domain, but in the information domain, to obtain downlink measurement results that are equivalent to the dynamic simulation in the signal domain and contain the complete flight dynamics. Software calculation replaces the complex hardware simulation link. When the telemetry and control transponder receives this downlink measurement result, it can use the downlink measurement result (downlink transmission link delay and Doppler frequency) and the delay and Doppler frequency corresponding to the uplink test simulation signal to calculate physical quantities such as distance and speed, thereby verifying the bidirectional measurement and calculation capability of the telemetry and control transponder.

[0018] In other words, this application can not only test the dynamic uplink acquisition and adaptation capabilities of the ground-based telemetry and control transponder, but also provide downlink measurement results for bidirectional measurement calculation through dynamic simulation of the information domain, thereby improving the coverage of ground testing and thus enhancing the reliability of the aerospace telemetry and control system.

[0019] Another objective of this application is to provide a dynamic simulation system for testing a telemetry and control transponder, comprising: The acquisition module is used to acquire the uplink baseband signals used for simulation testing, as well as the uplink frequency parameters and the simulated motion trajectory of the telemetry and control transponder; The uplink modulation module is used to perform Doppler frequency dynamic modulation on each of the uplink baseband signals based on the uplink frequency parameters and the simulated motion trajectory to obtain an uplink test simulation signal, which is then output to the telemetry and control transponder so that the telemetry and control transponder performs uplink testing based on the uplink test simulation signal. The downlink demodulation module is used to demodulate the downlink static signal received from the telemetry and control transponder to obtain the downlink measurement data corresponding to the downlink static signal; The downlink simulation test module is used to perform dynamic Doppler simulation on the downlink measurement data in the information domain to obtain the simulated downlink measurement results, and output the downlink measurement results to the telemetry and control transponder, so that the telemetry and control transponder can parse the downlink measurement results for testing.

[0020] The dynamic simulation system for testing telemetry and control transponders described in this application can dynamically simulate both the uplink and downlink transmission links by simulating motion trajectories, thereby generating uplink test simulation signals that closely resemble the characteristics of real-world ground-to-ground transmission links for testing the telemetry and control transponder. This allows for the realistic reproduction of channel changes caused by aircraft motion, thus improving the reliability of telemetry and control transponder testing. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart illustrating the dynamic simulation method for testing a transponder as described in an embodiment of this application. Figure 2 This is a schematic diagram of the uplink simulation test process in the dynamic simulation method for testing a telemetry and control transponder described in the embodiments of this application; Figure 3 This is a schematic diagram of the process for modulating the uplink baseband signal in the dynamic simulation method for testing a telemetry and control transponder described in this application embodiment; Figure 4 This is a schematic diagram of the up-conversion and combining process in the dynamic simulation method for testing the transponder described in this application embodiment. Detailed Implementation

[0022] To make the technical solution and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0024] Furthermore, it should be noted in the description of this application that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0026] The present application will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0027] An embodiment of the first aspect of this application provides a dynamic simulation method for testing a telemetry and control transponder. This method simulates the uplink and downlink transmission links by simulating the motion trajectory, thereby generating an uplink test simulation signal that closely resembles the characteristics of a real ground-to-ground transmission link for testing the telemetry and control transponder. This method can realistically reproduce the channel changes caused by aircraft motion, thus improving the reliability of telemetry and control transponder testing.

[0028] In the field of aerospace telemetry and control, the telemetry and control transponder is the core equipment for communication between spacecraft and ground equipment. It is usually installed on the spacecraft and is responsible for receiving measurement and remote control signals sent by ground equipment, or sending telemetry and ranging signals to ground equipment. The stability and accuracy of the transponder's transmission and reception performance directly determine the reliability of the space-to-ground transmission link. Therefore, it is necessary to conduct simulation tests on the transponder to ensure that it can work normally.

[0029] In related technologies, the testing methods for telemetry and control transponders suffer from low accuracy in dynamic simulation. Specifically, most related technologies use fixed-frequency, fixed-parameter test signals when testing the uplink transmission link of telemetry and control transponders.

[0030] However, in real-world applications, aircraft equipped with telemetry and control transponders are in a state of high-speed dynamic motion. The relative distance and relative speed between the aircraft and ground equipment are constantly changing, causing the frequency of the transmitted signals in the space-to-ground link to shift in real time, and the resulting frequency shift (Doppler frequency) also changes dynamically.

[0031] The testing methods using fixed-frequency or fixed-parameter signals in related technologies cannot reproduce the dynamic channel changes caused by the movement of the aircraft in a real space-to-ground link. In other words, it is difficult to simulate real channel characteristics such as dynamic Doppler, resulting in test scenarios that do not match the actual working environment, and consequently, the authenticity and reliability of the test results are low.

[0032] For example, when measuring the signal acquisition and tracking performance of a telemetry and control transponder using relevant testing methods, test results using a fixed-frequency uplink test signal show that the transponder can stably acquire and continuously lock onto the signal, and the demodulation accuracy meets the preset standard. However, in actual operation, the aircraft carrying the transponder is in a high-speed dynamic motion state, and the Doppler frequency of the signal in the space-to-ground link changes in real time. The transponder may not be able to track the dynamic frequency shift normally, leading to problems such as acquisition delay and demodulation errors, thus causing the test results to be inconsistent with the actual operating conditions.

[0033] In view of this, in order to overcome the shortcomings of related technologies, the test dynamic simulation method for the telemetry and control transponder in this embodiment combines... Figure 1 In terms of overall design, it includes the following steps S110-S140.

[0034] Step S110: Acquire the uplink baseband signals used for simulation testing, as well as the uplink frequency parameters and the simulated motion trajectory of the telemetry and control transponder.

[0035] Specifically, the uplink baseband signal refers to the digital signal generated by the test equipment (a dedicated device for testing the performance of telemetry and control transponders), which is not carrier-modulated and is used to transmit telemetry and control commands or measurement information. Its frequency is in the baseband range (usually 0~MHz) and is the original signal for subsequent Doppler modulation and up-conversion processing. This uplink baseband signal includes the uplink measurement baseband signal and the uplink remote control baseband signal.

[0036] Among them, the uplink measurement baseband signal refers to the baseband signal used to carry information related to distance and speed measurement between the ground and space. Its core function is to transmit it to the telemetry and control transponder through subsequent modulation, and complete the distance and speed measurement performance test in conjunction with the feedback signal of the telemetry and control transponder. Its signal content includes measurement-related bit streams such as distance measurement code and synchronization code.

[0037] Uplink remote control baseband signal refers to the baseband signal used to carry remote control commands (such as attitude adjustment, command issuance, etc.) from ground equipment to the aircraft. Its core function is to simulate the remote control operation of the telemetry and control transponder by ground equipment (used for actual telemetry and control communication of on-orbit aircraft) and verify the telemetry and control transponder's performance in receiving, demodulating and responding to remote control commands. Its signal content usually includes remote control command code, check code and other control-related bit streams.

[0038] It is worth noting that in step S110 of this embodiment, the acquired uplink baseband signals may specifically include at least one uplink measurement baseband signal and one uplink remote control baseband signal.

[0039] In addition, the simulated motion trajectory of the telemetry and control transponder refers to the trajectory data generated by simulation software based on the actual flight mission of the spacecraft (such as low Earth orbit or deep space exploration orbit), simulating the position and speed changes of the telemetry and control transponder as it moves with the spacecraft, in order to simulate the dynamic motion state of the spacecraft during actual flight. Specifically, it can include parameters such as the spatial coordinates (longitude, latitude, altitude) of the telemetry and control transponder at different times, the relative distance to ground equipment, and the relative radial velocity.

[0040] Furthermore, the uplink frequency parameter in step S110 is a core parameter used to determine the uplink signal frequency characteristics and support subsequent signal modulation and Doppler frequency calculation. Specifically, this uplink frequency parameter may include the uplink carrier frequency and the spreading code rate.

[0041] The uplink carrier frequency refers to the radio frequency carrier reference frequency (usually in the GHz range, such as 2.2GHz) that the ground test equipment modulates the uplink baseband signal and transmits it to the telemetry and control transponder. It is the "carrier frequency" of the uplink signal and is used to generate a carrier signal with dynamic offset.

[0042] Spread code rate refers to the transition rate of the pseudocode sequence used when spreading and modulating uplink measurement baseband signals, uplink remote control baseband signals, etc. The unit is Chip / s (chips per second), usually in the Mcps range (e.g., 10 Mcps), which is used to determine the transition speed of the pseudocode.

[0043] More specifically, in step S110, the uplink baseband signal can be generated by the tester inputting corresponding instructions to the baseband signal simulation generation module in the test equipment. Specifically, the baseband signal simulation generation module can generate a digital baseband signal containing measurement information or remote control instructions according to a preset measurement and control protocol (such as a ranging protocol or a remote control protocol), thereby obtaining the uplink measurement baseband signal and the uplink remote control baseband signal respectively.

[0044] In some embodiments, the uplink baseband signal may also be generated by the ground equipment's built-in signal generation module, which is then input by the tester into the test equipment, and the test equipment inputs the corresponding simulated test command into the ground equipment.

[0045] In step S110, the uplink frequency parameter can be preset by the tester in the parameter configuration module of the ground test equipment. Specifically, the tester can set the corresponding uplink carrier frequency and spreading code rate according to the actual operating parameters of the telemetry and control transponder (such as the receiving carrier frequency range and spreading scheme of the telemetry and control transponder) to obtain the uplink frequency parameter. The value of this uplink frequency parameter can be flexibly adjusted by the tester according to the test scenario to match the working mechanism of the transponder.

[0046] In step S110, the simulated motion trajectory of the telemetry and control transponder can be generated by acquiring the historical motion trajectories of other telemetry and control transponders and using orbit simulation software (such as STK simulation software) based on these historical motion trajectories. In some embodiments, the trajectory data such as the spatial position and relative velocity of the telemetry and control transponder at different times can also be simulated and generated based on the aircraft's preset flight mission (such as orbital altitude, flight speed, and orbital inclination). After generation, the data is imported into ground testing equipment to obtain the simulated motion trajectory.

[0047] Step S120: Based on the uplink frequency parameters and the simulated motion trajectory, perform Doppler frequency dynamic modulation on each uplink baseband signal to obtain the uplink test simulation signal, and output it to the telemetry and control transponder so that the telemetry and control transponder can perform uplink tests based on the uplink test simulation signal.

[0048] In some embodiments, refer to Figure 2 In step S120 above, based on the uplink frequency parameters and the simulated motion trajectory, the Doppler frequency is dynamically modulated on each uplink baseband signal to obtain the uplink test simulation signal, which is then output to the telemetry and control transponder so that the telemetry and control transponder performs uplink testing based on the uplink test simulation signal. Specifically, this may include the following steps S121-S123.

[0049] Step S121: Based on the uplink frequency parameters and the simulated motion trajectory, calculate the Doppler frequency that dynamically changes due to the movement of the telemetry and control transponder in the ground-to-ground transmission link.

[0050] Specifically, the space-to-ground transmission link refers to the signal transmission link between the ground test equipment and the transponder under test, as simulated in this embodiment. It serves as an equivalent signal transmission path between "ground equipment and the transponder on the orbiting spacecraft" in a real-world scenario. In a real-world scenario, the core function of the space-to-ground transmission link is to carry the transmission of uplink and downlink signals.

[0051] In real-world scenarios, the telemetry, tracking, and command (TT&C) transponder moves at high speed with the aircraft, causing the relative motion between the transmitting end (ground equipment) and the receiving end (TT&C transponder) in the space-to-ground transmission link to constantly change. This results in a frequency offset between the uplink signal transmitted by the ground equipment and the signal received by the TT&C transponder. This frequency offset is the Doppler frequency, and its sign and magnitude directly reflect the relative motion state (closer or farther away, faster or slower) between the TT&C transponder and the ground equipment.

[0052] The telemetry, tracking, and command (TT&C) transponder is constantly changing in real time along with the trajectory of the aircraft. Therefore, the relative motion between the TT&C transponder and the ground equipment is constantly changing, resulting in the Doppler frequency being in a dynamic process.

[0053] In order to accurately reproduce the dynamic Doppler frequency in the space-to-ground transmission link, in step S121 of this embodiment, the Doppler frequency that dynamically changes due to the movement of the telemetry and control transponder in the space-to-ground transmission link is calculated so that the Doppler frequency can be used for Doppler modulation processing in step S122 to achieve high-precision simulation of dynamic Doppler, thereby enabling the uplink test simulation signal to more realistically reflect the channel changes caused by the movement of the aircraft.

[0054] Since the magnitude and variation of the Doppler frequency are directly determined by the relative motion state of the telemetry and control transponder (provided by the simulated motion trajectory), in step S121, the dynamically changing Doppler frequency at different times can be calculated by using the simulated motion trajectory and the uplink frequency parameters.

[0055] In some embodiments, calculating the dynamically changing Doppler frequency in the ground-to-ground transmission link due to the movement of the telemetry and control transponder in step S121 may specifically include: taking a discrete sampling point at preset time intervals in the simulated motion trajectory; calculating the Doppler frequency and Doppler frequency change rate corresponding to each discrete sampling point based on the simulated motion trajectory; and performing linear interpolation between adjacent discrete sampling points based on the Doppler frequency and Doppler frequency change rate corresponding to each discrete sampling point to obtain each intermediate point and the Doppler frequency corresponding to each intermediate point.

[0056] Specifically, in the simulated motion trajectory, the aircraft's position and velocity change continuously over time, and the corresponding Doppler frequency also exhibits continuous variation. Directly using all data points from the original simulated motion trajectory for real-time signal modulation would result in excessive computation and high real-time processing pressure. Therefore, in this embodiment, several intermediate points are selected, and the Doppler frequencies of these intermediate points are calculated to perform Doppler modulation on the signal.

[0057] However, if only a small number of sparse trajectory points are used for modulation, it is easy to cause a step jump in the Doppler frequency in the time domain, which is inconsistent with the smooth and continuous dynamic characteristics in the real space-ground link, and thus affects the dynamic response test accuracy of the telemetry and control transponder tracking loop.

[0058] Specifically, high-frequency carriers (such as L-band and S-band) are extremely sensitive to phase changes. If the time interval between two adjacent intermediate points is too large (e.g., on the order of microseconds), the Doppler frequency shift and multipath delay between the two adjacent intermediate points will change abruptly under high-speed motion of the aircraft, resulting in phase discontinuities in the subsequently modulated signal. This phase discontinuity usually manifests as severe spectral spurious signals and phase noise in the frequency domain.

[0059] Therefore, in this embodiment, the interval between two adjacent intermediate points should not be greater than the preset required time interval (e.g., 20ns), so as to ensure a smooth transition of phase change and make the spectral purity of the synthesized signal meet the stringent radio frequency indicators.

[0060] However, if the Doppler frequency of the simulated motion trajectory is calculated every 20ns (or even smaller channel intervals), it requires a large amount of computing resources, which is usually difficult for hardware computing power to handle.

[0061] Therefore, in this embodiment, when calculating the Doppler frequency, a discrete sampling point is taken every preset time interval (which should be greater than the preset time interval, i.e., greater than 20ns, and the hardware computing power of the simulation device should be able to handle the Doppler frequency calculation of each discrete sampling point, for example, the preset time interval can be 1ms) to obtain multiple discrete sampling points.

[0062] Then, for each discrete sampling point, the corresponding Doppler frequency and Doppler frequency change rate are calculated using the simulated motion trajectory. Then, linear interpolation is performed between each pair of adjacent discrete sampling points to obtain each intermediate point (including each discrete sampling point and each interpolation point obtained by linear interpolation between discrete sampling points) and the corresponding Doppler frequency of each intermediate point, so that the interval between two adjacent intermediate points is not greater than the preset time interval, for example, the interval between two adjacent intermediate points is 20ns.

[0063] More specifically, calculating the Doppler frequency and rate of change of Doppler frequency corresponding to each discrete sampling point based on the simulated motion trajectory can include: determining the radial velocity v of the telemetry and control transponder relative to the ground test equipment at the corresponding moment based on the aircraft's position and velocity information at each discrete sampling point. r (Radial velocity is the relative velocity along the line connecting the telemetry and control transponder and the ground equipment); then, combining the uplink carrier frequency f0 and the speed of light C, calculate the Doppler frequency fd corresponding to this discrete sampling point (fd = f0 × v).r / C). After obtaining the Doppler frequencies of adjacent discrete sampling points, the rate of change of the Doppler frequency corresponding to the discrete sampling point is calculated based on the difference between the Doppler frequency of the current discrete sampling point and the Doppler frequency of the next discrete sampling point, and the time interval between the two discrete sampling points.

[0064] In other embodiments, the process of determining the Doppler frequency and Doppler frequency change rate corresponding to each discrete sampling point may also include: using a high-precision flight trajectory model, calculating a ground-to-ground instantaneous radial Doppler frequency and Doppler frequency change rate every preset time interval (e.g., 1ms) to obtain the Doppler frequency and Doppler frequency change rate of a discrete sampling point.

[0065] The high-precision flight trajectory model is a known motion model of the spacecraft. For example, for low-Earth orbit satellites, this high-precision flight trajectory model is typically an orbital parameter model. This orbital parameter module can calculate the satellite's real-time velocity and real-time acceleration, and then convert them into Doppler frequency and Doppler frequency change rate. Alternatively, the high-precision flight trajectory model can be trajectory file data, from which the spacecraft's position and velocity information are calculated, thereby determining the Doppler frequency and Doppler frequency change rate.

[0066] Then, linear interpolation is performed between two adjacent discrete sampling points to obtain each intermediate point and the corresponding Doppler frequency. Specifically, this may include: firstly, determining the number of interpolation points based on the discrete sampling point interval (e.g., 1ms) and the target intermediate point interval (e.g., the preset time interval mentioned above, i.e., 20ns).

[0067] For example, 50,000 interpolation points are uniformly inserted between two adjacent discrete sampling points, ensuring that the time interval between adjacent interpolation points is no greater than a preset time interval (20 ns). Using the Doppler frequency change rate corresponding to the previous discrete sampling point as the slope, the Doppler frequency corresponding to each interpolation point is calculated by linear interpolation.

[0068] Specifically, this linear interpolation process can be implemented using an FPGA (Field Programmable Gate Array). This FPGA possesses high-speed parallel processing capabilities, enabling it to perform high-speed linear interpolation operations at speeds exceeding 10,000 times (e.g., 50,000 times), ensuring the real-time smoothness and spectral purity of the Doppler frequency simulation. The formula for linear interpolation is shown below: .in, Let be the Doppler frequency at time t. This refers to the Doppler frequency corresponding to the first of the two discrete sampling points. This represents the rate of change of the Doppler frequency corresponding to the previous discrete sampling point.

[0069] Therefore, by first taking discrete sampling points at preset time intervals to calculate the Doppler frequency corresponding to each discrete sampling point, and then determining the Doppler frequency of each interpolation point through linear interpolation, the calculation of the Doppler frequency of each intermediate point can be realized, which can reduce the amount of computation in simulation testing.

[0070] After calculating the Doppler frequency, the following steps S122-S123 are performed to modulate and upconvert each uplink baseband signal.

[0071] Step S122: Modulate each uplink baseband signal according to the Doppler frequency.

[0072] Specifically, modulating the uplink baseband signal means superimposing the dynamically changing Doppler frequency characteristics onto the original uplink baseband signal, so that the frequency and phase of the baseband signal change in real time with the Doppler effect, thereby simulating the real channel characteristics of the space-to-ground transmission link under high-speed aircraft movement.

[0073] During the test, the uplink baseband signal is modulated to ensure that the signal received by the transponder under test is consistent with the signal during actual on-orbit operation. This allows for the accurate verification of the transponder's signal acquisition, tracking, and demodulation capabilities under dynamic Doppler frequency shift, ensuring that the test results reflect the transponder's actual operating performance.

[0074] More specifically, in some embodiments, the following: Figure 3 As shown, in step S122, the modulation processing of each uplink baseband signal may specifically include the following steps S1221-S1225.

[0075] Step S1221: Calculate the pseudo-code Doppler frequency at each time step based on the uplink carrier frequency, spreading code rate, and the corresponding Doppler frequency at each time step.

[0076] Specifically, in a communication system, the signal sent by ground equipment to the telemetry, tracking, and command (TT&C) transponder mainly consists of two parts: a carrier wave to carry the signal and a pseudocode sequence to carry data such as ranging. The pseudocode sequence is a code sequence that repeats continuously according to a fixed pattern. The TT&C transponder can achieve signal synchronization and distance calculation by recognizing the changing patterns of this pseudocode sequence.

[0077] When an aircraft moves at high speed, the signal received by the telemetry and control transponder will be significantly different from the signal transmitted from the ground. This difference will be reflected in both the carrier wave and the pseudocode sequence: on the one hand, the aircraft's movement will cause the carrier wave frequency to change, that is, the carrier wave frequency will experience a Doppler shift; on the other hand, such movement will also cause the transmission speed of the pseudocode sequence to change, that is, the chip rate of the pseudocode sequence will shift, and this chip rate shift is the pseudocode Doppler frequency.

[0078] Because the transmission rate of the pseudocode sequence dynamically changes with the pseudocode Doppler frequency, its position on the time axis gradually deviates from its original static position over time. This accumulated positional offset is called the pseudocode sequence phase. The pseudocode sequence phase characterizes the offset of the received pseudocode relative to the local reference pseudocode, and this offset corresponds one-to-one with the signal propagation delay in space. In other words, the change in the pseudocode phase (or code phase for short) is directly equivalent to the change in delay. The pseudocode sequence phase is used to simulate the dynamic delay in a real-world transmission link.

[0079] Therefore, in this embodiment, in step S1221, the pseudo-code Doppler frequency at each time point is calculated first. Then, in step S1222, the pseudo-code sequence phase at each time point is calculated based on the pseudo-code Doppler frequency. Finally, in steps S1223-S1225, each uplink baseband signal is modulated based on the pseudo-code sequence phase.

[0080] More specifically, in step S1221, the pseudo-code Doppler frequency reflects the chip rate offset of the pseudo-code sequence under dynamic channel conditions, and it can be calculated using the following formula.

[0081] (Formula 1).

[0082] Among them, the For pseudocode Doppler frequency, The instantaneous Doppler frequency, For uplink carrier frequency, This represents the spreading code rate.

[0083] Step S1222: Calculate the phase of the pseudocode sequence at each time step based on the pseudocode Doppler frequency at each time step.

[0084] Among them, the pseudocode sequence phase is used to characterize the real-time phase offset of the pseudocode sequence under dynamic channel. The pseudocode sequence phase includes both the fixed offset caused by the initial distance and the dynamic offset caused by motion Doppler.

[0085] Specifically, after obtaining the pseudocode Doppler frequency at each moment, the phase of the dynamically changing pseudocode sequence is generated in real time in the digital domain through an accumulator, that is, the phase of the pseudocode sequence at each moment is calculated.

[0086] More specifically, in some embodiments, the phase of the pseudocode sequence can be calculated using the following formula 2.

[0087] (Formula 2).

[0088] in, It represents the phase of the pseudocode sequence. Let be the initial pseudocode phase, where C is the speed of light. This represents the initial distance of the telemetry and control transponder.

[0089] After calculating the pseudocode sequence phase in step S1222, steps S1223-S1225 can be executed to modulate the uplink baseband signal according to the pseudocode sequence phase.

[0090] Step S1223: Determine the pseudocode sequence based on the phase of the pseudocode sequence.

[0091] Among them, the pseudo-random code sequence refers to the pseudo-random code sequence used for signal synchronization, despreading and ranging in telemetry and control communication. It consists of a series of code chips arranged according to a fixed pattern.

[0092] Specifically, modulating the uplink baseband signal using the pseudocode sequence phase refers to controlling the pseudocode generator (a module used to generate fixed-format pseudocode sequences, whose output pseudocode sequence time is determined by the current pseudocode sequence phase) to output the pseudocode sequence at the corresponding time according to the real-time dynamically changing pseudocode sequence phase. Then, the uplink baseband signal is modulated using the pseudocode sequences corresponding to each time, so that the uplink baseband signal carries the phase change characteristics consistent with the real dynamic channel, thereby reproducing the dynamic time delay changes and Doppler effect caused by the aircraft motion.

[0093] More specifically, each uplink baseband signal operates independently, undergoing modulation processing based on the same dynamically changing pseudo-code sequence phase. Taking the modulation processing of one uplink baseband signal as an example, in a real telemetry and control system, the command or measurement information contained in the uplink baseband signal needs to be spread-spectrum modulated using a pseudo-code sequence so that the uplink baseband signal can be captured by the telemetry and control transponder after transmission. Simultaneously, due to the Doppler effect caused by the aircraft's motion, the rhythm and position of the pseudo-code sequence will shift. Therefore, dynamically changing pseudo-code sequence phase is required to control the real-time output of the pseudo-code sequence in order to realistically simulate the signal characteristics under high-dynamic environments.

[0094] That is, in step S1223, the pseudo-code sequence is first determined based on the phase of the pseudo-code sequence. Specifically, determining the pseudo-code sequence based on the phase of the pseudo-code sequence may include: inputting the phase of the pseudo-code sequence calculated in real time into the pseudo-code generation module, so that the pseudo-code generation module determines which chip in the pseudo-code sequence should be output at the current moment based on the phase of the pseudo-code sequence, so that the output pseudo-code sequence is synchronized with the dynamic offset caused by Doppler in rhythm and position, thus obtaining the pseudo-code sequence.

[0095] Step S1224: Determine the carrier signal based on the preset carrier frequency and the corresponding Doppler frequency at each time.

[0096] The carrier signal is a high-frequency sinusoidal signal used to carry the baseband signal onto the radio frequency band for transmission. In the field of measurement and control communication, high frequency specifically refers to the radio frequency band, whose frequency is much higher than the bandwidth of the baseband signal (baseband is usually in the range of kHz to hundreds of kHz), generally in the range of hundreds of MHz to GHz, and can be transmitted through space radiation via antennas.

[0097] The function of this carrier signal is to provide a transmission medium for the baseband signal, enabling the signal to be transmitted through the antenna and received by the telemetry and control transponder.

[0098] In dynamic testing scenarios, the carrier frequency actually received by the telemetry and control transponder is not a fixed carrier frequency, but rather a Doppler shift caused by the aircraft's motion, based on a fixed carrier frequency. Therefore, the carrier signal determined in step S1224 is not a stationary standard carrier signal, but a carrier signal with dynamic Doppler shift. The frequency of this carrier signal changes continuously over time to realistically simulate the frequency shift characteristics caused by the aircraft's motion.

[0099] Specifically, the process of determining the carrier signal includes: matching the preset carrier frequency with the Doppler frequency at the current moment. The instantaneous carrier frequency is obtained by superimposing the two signals. This instantaneous carrier frequency is then input into a DDS (Direct Digital Synthesizer), which outputs a carrier signal that dynamically changes with Doppler.

[0100] In this embodiment, the preset carrier frequency is the uplink carrier frequency in the above embodiment. Its frequency can be specifically set as the standard carrier frequency in the uplink transmission link of the telemetry and control transponder. The frequency can be selected in the specified uplink telemetry and control frequency band, such as the S band, or more specifically, a frequency in the range of 2025~2120MHz, such as 2100MHz.

[0101] Specifically, DDS mainly accumulates the frequency control word based on the input instantaneous carrier frequency through a high-precision phase accumulator to obtain the instantaneous phase. Then, it searches for the sine wave value through the phase and outputs a continuous and smooth high-frequency sine carrier after digital-to-analog conversion, thus obtaining the carrier signal.

[0102] Step S1225: Modulate the uplink baseband signal according to the carrier signal and the pseudocode sequence.

[0103] After the carrier signal and pseudocode sequence are determined in steps S1223 and S1224, the uplink baseband signal can be modulated using the carrier signal and pseudocode sequence.

[0104] More specifically, in some embodiments, in step S1225, the uplink baseband signal is modulated based on the carrier signal and the pseudocode sequence, which may specifically include:

[0105] First, determine the uplink information data frame carried by the uplink baseband signal.

[0106] Specifically, an uplink information data frame refers to a fixed-structure, fixed-length data frame that organizes the useful information that actually needs to be transmitted to the telemetry and control transponder according to a preset telemetry and control communication protocol (referring to the communication format and interaction rules agreed upon in advance between the ground equipment and the telemetry and control transponder being measured).

[0107] Depending on the signal type, the uplink information data frame can be remote control command data, ranging guidance data, etc., and is represented by the symbol d(t) in this embodiment.

[0108] The uplink baseband signal is essentially the baseband waveform signal carrying the uplink information data frame. In uplink transmission link simulation testing, the baseband signal generation module typically generates the uplink information data frame d(t) according to the test requirements, and then converts it into the corresponding baseband waveform to form the uplink baseband signal. Therefore, the uplink information data frame can be directly determined from the baseband signal generation module.

[0109] Then, the uplink information data frame is subjected to direct sequence spread spectrum modulation using the pseudocode sequence to obtain the spread spectrum modulated uplink baseband signal.

[0110] Specifically, direct sequence spread spectrum modulation (DSSM) refers to using pseudocode sequences and uplink data frames to perform bit-level operations, extending the bandwidth of narrowband uplink data frames to wideband for spread spectrum modulation.

[0111] More specifically, the pseudocode sequence c(t) and the uplink information data frame d(t) can be input into an XOR logic gate for bit-by-bit operation. Since the chip rate of the pseudocode sequence is much higher than the information data rate, after the XOR operation, the original narrowband information data is expanded to a wider frequency range, and the signal form is transformed from a low-speed data sequence to a high-speed spread spectrum sequence, thereby completing the spread spectrum process and obtaining the spread spectrum modulated uplink baseband signal.

[0112] Finally, the uplink baseband signal after spread spectrum modulation is processed by carrier modulation using the carrier signal to obtain the modulated uplink baseband signal.

[0113] Specifically, the spread spectrum modulated uplink baseband signal is used as the modulation signal and multiplied with the carrier signal. By changing the amplitude or phase, the spectrum of the baseband signal is "shifted" to the frequency band where the carrier frequency is located, thus obtaining the modulated uplink baseband signal.

[0114] Therefore, by using a pseudo-code sequence to spread spectrum modulate the uplink baseband signal, and then using a carrier signal to carrier modulate the spread spectrum modulated uplink baseband signal, the modulated uplink baseband signal carries real-time changing Doppler frequency characteristics and pseudo-code dynamic phase characteristics. This allows for a realistic simulation of the uplink signal transmission process under dynamic motion scenarios of aircraft, thereby improving the reliability of performance testing of telemetry and control transponders.

[0115] After obtaining the modulated uplink baseband signals, step S123 can be executed to perform up-conversion and combining processing on each uplink baseband signal to obtain an uplink test analog signal for testing the transponder.

[0116] Step S123: Up-convert and combine each uplink baseband signal after modulation to obtain the uplink test simulation signal of radio frequency, and send it to the telemetry and control transponder so that the telemetry and control transponder can perform tests based on the uplink test simulation signal.

[0117] Specifically, after Doppler frequency modulation processing, each uplink baseband signal carries dynamic Doppler frequency characteristics, and its signal characteristics are basically consistent with the dynamic Doppler signals generated by the movement of the aircraft in the real ground-to-ground transmission link.

[0118] The modulated uplink baseband signals are then upconverted and combined. Specifically, for the transponder under test, the signals received during actual on-orbit operation are in the radio frequency band, while the modulated uplink baseband signals are still in the low-frequency baseband band (generally a few kHz to several hundred kHz, which cannot be directly transmitted via antenna), and cannot be directly recognized and received by the transponder. Therefore, it is necessary to upconvert the uplink baseband signals to a preset radio frequency band (i.e., the 100 MHz-GHz radio frequency band in the above embodiment), so that the signals have the frequency characteristics that can be received by the transponder.

[0119] On the other hand, this embodiment involves multiple uplink baseband signals (such as remote control signals, ranging signals, etc.). Each uplink baseband signal is modulated separately and becomes an independent signal. In this embodiment, to simulate the scenario of coordinated transmission of multiple uplink signals in a real-world ground-to-ground transmission link, the uplink signals are also combined. This integrates multiple independent uplink signals into a single unified signal, ensuring synchronous transmission of all signals and simplifying the uplink signal transmission link.

[0120] Therefore, in some embodiments, reference is made to Figure 4 In the case where the uplink baseband signal includes an uplink measurement baseband signal and an uplink remote control baseband signal, in step S123, the modulated uplink baseband signals are upconverted and combined to obtain the uplink test analog signal of radio frequency, which may specifically include the following steps S1231-S1234.

[0121] Step S1231: Perform pulse shaping processing on the modulated uplink measurement baseband signal and the modulated uplink remote control baseband signal respectively to obtain the first digital intermediate frequency sequence and the second digital intermediate frequency sequence.

[0122] Specifically, the modulated uplink measurement baseband signal refers to the uplink measurement baseband signal after being modulated by Doppler frequency in step S122. Similarly, the modulated uplink remote control baseband signal is also the uplink remote control baseband signal after being modulated by Doppler frequency in step S122.

[0123] In step S1231, each uplink baseband signal is independently pulse-shaped, and the corresponding digital intermediate frequency (IF) sequence is obtained after pulse shaping. Specifically, pulse shaping is performed on the modulated uplink measurement baseband signal to obtain the first IF sequence. Pulse shaping is performed on the modulated uplink remote control baseband signal to obtain the second IF sequence.

[0124] In this context, a digital intermediate frequency (IF) sequence refers to a discrete signal sequence represented in digital form within the intermediate frequency band (typically tens of kHz to tens of MHz; in telemetry and control spread spectrum systems, 70MHz, 42MHz, and 10.7MHz are commonly used, but this is not a specific limitation). Pulse shaping processing refers to filtering the digital uplink baseband signal using a shaping filter (such as a raised cosine filter). Its purpose is to reduce inter-symbol interference and ensure that the signal bandwidth and spectrum meet the system transmission requirements.

[0125] Specifically, the uplink baseband signals after Doppler modulation are input to pulse shaping filters. The pulse shaping filters perform weighting and interpolation processing on each uplink baseband signal according to preset shaping characteristics, so that the signal waveform is smooth and the spectrum is regular, thereby outputting the corresponding digital intermediate frequency sequence.

[0126] Among them, the preset shaping characteristics refer to the frequency response and waveform constraint rules set in advance for the pulse shaping filter in order to suppress inter-symbol interference, control signal bandwidth and spectral sidelobe attenuation. The raised cosine filtering characteristics are usually adopted.

[0127] Step S1232: Perform linear superposition and combining of the first digital intermediate frequency sequence and the second digital intermediate frequency sequence to obtain a composite data intermediate frequency signal.

[0128] Among them, the composite data intermediate frequency signal refers to a single integrated digital intermediate frequency signal formed by linearly superimposing and combining multiple digital intermediate frequency signals (i.e., the first digital intermediate frequency sequence and the second digital intermediate frequency sequence) according to a preset amplitude ratio (referring to the relative amplitude weights pre-configured for the uplink measurement signal and the uplink remote control signal according to the test scenario requirements, used to control the power ratio of the two signals after combining, ensuring that the two signals are power matched, do not suppress each other, and meet the receiving sensitivity requirements when transmitted in the same intermediate frequency channel).

[0129] Specifically, linear superposition and merging refers to the algebraic addition of two digital intermediate frequency sequences point by point according to the same time scale, so as to merge multiple signals in the same intermediate frequency band.

[0130] Step S1233: Convert the composite digital intermediate frequency signal into an analog signal to obtain an analog intermediate frequency signal.

[0131] Specifically, the composite digital intermediate frequency signal is a discrete signal in the digital domain, while subsequent mixing, up-conversion, and other processing need to be performed in the continuous analog domain. Therefore, the composite digital intermediate frequency signal needs to be converted from a digital to an analog signal to obtain an analog intermediate frequency signal. Specifically, the composite digital intermediate frequency signal is input to the digital-to-analog conversion unit, which converts the composite digital intermediate frequency signal from a digital signal to an analog signal to obtain the analog intermediate frequency signal, and then step S1234 is executed.

[0132] Step S1234: Mix the analog intermediate frequency signal with the preset radio frequency local oscillator signal to obtain the radio frequency uplink test analog signal.

[0133] The preset RF local oscillator signal refers to a high-frequency sinusoidal oscillation signal generated by the frequency synthesizer using a preset uplink RF local oscillator frequency, used to provide the frequency reference required for mixing. The preset uplink RF local oscillator frequency is set to increase the frequency of the analog intermediate frequency signal to the RF band; its value is set according to the required frequency and the frequency of the analog intermediate frequency signal. RF refers to a high-frequency band suitable for transmission via antenna and capable of wireless transmission in space.

[0134] Specifically, the receiving antenna of the telemetry and control transponder only supports the reception of radio frequency band signals. Intermediate frequency signals (such as the tens of kHz to tens of MHz mentioned above) cannot be directly radiated and transmitted, nor can they be correctly received by the telemetry and control transponder. Therefore, it is necessary to upconvert the analog intermediate frequency signal to the radio frequency band through mixing to obtain the radio frequency uplink test analog signal.

[0135] More specifically, the analog intermediate frequency (IF) signal and the preset radio frequency (RF) local oscillator (LOO) signal are input to a mixer for mixing. The spectrum of the analog IF signal is shifted to the RF band, ultimately obtaining the RF uplink test analog signal. This signal retains all dynamic Doppler characteristics, pseudocode characteristics, and original information, and can be directly transmitted to the telemetry and control transponder to conduct high dynamic range reception performance tests.

[0136] Therefore, through steps S1231-S1234, in the digital intermediate frequency stage, the uplink measurement baseband signal and the uplink remote control baseband signal are respectively subjected to independent baseband modulation and pulse shaping to generate two independent digital intermediate frequency sequences (i.e., the first digital intermediate frequency sequence and the second digital intermediate frequency sequence), and are linearly superimposed and combined in the digital domain to form a composite digital intermediate frequency stream (i.e., the composite data intermediate frequency signal mentioned above) containing complete dual service information (i.e., containing remote control and measurement dual service information).

[0137] Subsequently, this single composite digital stream (i.e., the aforementioned composite data intermediate frequency signal) is converted into an analog intermediate frequency signal via a digital-to-analog converter (DAC) and directly fed into the shared upconversion channel. In the upconversion stage, the two uplink baseband signals are no longer distinguished but treated as a whole and mixed with the same highly stable preset RF local oscillator signal. Through a single frequency shift, the composite analog intermediate frequency signal is directly converted into the final RF uplink test analog signal. This "digital splitting and synthesis, unified RF transmission" architecture not only eliminates the phase inconsistency and hardware redundancy problems caused by multi-channel upconversion but also maximizes power amplifier efficiency and ensures the coexistence of measurement and remote control signals in the spectrum.

[0138] The uplink test simulation signal for this radio frequency is shown in the following formula: .

[0139] in, This is the uplink test simulation signal for this radio frequency. S1(t) is the preset uplink RF local oscillator frequency of the preset RF local oscillator signal. S2(t) is the uplink measurement baseband signal after Doppler modulation processing, and S2(t) is the uplink remote control baseband signal after Doppler modulation processing.

[0140] in, .

[0141] This indicates the signal amplitude of the uplink measured baseband signal. This refers to the uplink information data frame in the uplink measurement baseband signal (which may include the back-returning code phase and Doppler frequency, which may be the dynamic code phase and dynamic Doppler frequency of the downlink transmission link of the telemetry and control transponder). This represents the pseudocode sequence corresponding to the uplink measured baseband signal. The intermediate frequency (IF) of the uplink baseband signal is measured. This refers to the Doppler frequency corresponding to the uplink baseband signal.

[0142] in, .

[0143] This indicates the signal amplitude of the uplink remote control baseband signal. This indicates an uplink information data frame in the uplink remote control baseband signal that conforms to the protocol (which may contain the back-returning code phase and Doppler frequency, which may be the dynamic code phase and dynamic Doppler frequency of the downlink transmission link of the telemetry and control transponder). This represents the pseudocode sequence corresponding to the uplink remote control baseband signal. This is the intermediate frequency of the uplink remote control baseband signal. This is the Doppler frequency corresponding to the uplink remote control baseband signal.

[0144] The telemetry and control transponder then receives the uplink test simulation signal, demodulates it, and responds to the relevant instructions carried by the uplink test simulation signal.

[0145] The test equipment in this embodiment also simulates the remote control interface of the telemetry and control transponder through the remote control data interface, samples the bus data output by the telemetry and control transponder (e.g., remote control bus data), and parses the bus data according to the interface protocol of the telemetry and control transponder (e.g., level, timing, handshake method) to obtain the readback command of the telemetry and control transponder.

[0146] The testing equipment can then compare the original transmitted commands (e.g., remote control commands) with the read-back commands to verify the correctness of command reception, demodulation reliability, and data parsing accuracy of the telemetry and control transponder. For example, by comparing the original transmitted commands and read-back commands, the testing equipment performs bit data and CRC (Cyclic Redundancy Check) verification to statistically analyze the remote control command reception error rate of the telemetry and control transponder, thereby achieving automatic comparison and closed-loop verification of the consistency and reliability of remote control command transmission and reception.

[0147] This approach, on the one hand, calculates dynamic Doppler in real time by simulating the motion trajectory and generates uplink test simulation signals for radio frequency that closely resemble real-world ground-to-ground transmission links. This accurately reproduces the channel changes caused by aircraft motion, thereby improving test reliability. On the other hand, since each test does not involve sending only one uplink signal for simulation, but rather simulates the actual scenario where a telemetry and control transponder might simultaneously receive multiple uplink signals, it more closely resembles the real-world usage scenario of a telemetry and control transponder, thus also improving the reliability of the test results.

[0148] The above embodiments enable the simulation of the uplink transmission link for dynamic simulation testing of the telemetry, tracking, and command (TT&C) transponder. This embodiment also requires simulation testing of the downlink transmission link.

[0149] Step S130: Demodulate the downlink measurement data corresponding to the downlink static signal from the received downlink static signal sent by the telemetry and control transponder.

[0150] The downlink measurement data includes the static code phase corresponding to the downlink static signal and the corresponding static carrier Doppler frequency.

[0151] Specifically, in step S130, demodulating the downlink measurement data corresponding to the downlink static signal from the received downlink static signal sent by the telemetry and control transponder may include: receiving the downlink static signal sent by the telemetry and control transponder; generating a down-converted local oscillator signal based on a preset downlink radio frequency local oscillator frequency; inputting the down-converted local oscillator signal and the downlink static signal into a mixer for mixing to obtain a mixed signal; filtering the mixed signal to retain the intermediate frequency difference frequency component in the mixed signal to obtain an intermediate frequency difference frequency signal; and demodulating the intermediate frequency difference frequency signal to obtain the downlink valid data, as well as the static code phase and the corresponding static carrier Doppler frequency of the downlink static signal.

[0152] Specifically, the downlink static signal is the downlink radio frequency signal sent by the telemetry and control transponder, in order to... This indicates that the downlink static signal may include downlink measurement radio frequency signals and downlink telemetry radio frequency signals.

[0153] The downlink measurement radio frequency signal is used by ground equipment for ranging calculation. It carries distance-related information between the telemetry transponder and the ground equipment and is the core signal for the ground equipment to complete the ranging test. The downlink telemetry radio frequency signal is used to provide feedback on the operating status of the simulated aircraft and the telemetry transponder itself. It carries telemetry data (such as equipment operating parameters, environmental parameters, etc.) and is used to test the ground equipment's ability to receive, demodulate, and analyze telemetry signals.

[0154] Then, a down-converted local oscillator signal is generated based on the preset downlink RF local oscillator frequency. Specifically, the preset downlink RF local oscillator frequency refers to a pre-configured reference frequency used to convert the downlink RF signal to an intermediate frequency (IF), and its value is determined based on the carrier frequency of the downlink RF signal and the target IF frequency. It is worth noting that although the downlink measurement RF signal and the downlink telemetry RF signal have different frequencies, they are designed to fall into two predetermined, non-interfering IF channels after mixing with the same local oscillator.

[0155] The down-conversion local oscillator signal refers to a high-frequency sinusoidal oscillation signal generated based on the preset downlink radio frequency local oscillator frequency, which is used to mix with the downlink radio frequency signal to achieve frequency shifting.

[0156] The down-converted local oscillator signal and the downlink static signal are then mixed to obtain a mixed signal. The mixed signal is then filtered to retain the intermediate frequency difference component, thus obtaining the intermediate frequency difference signal.

[0157] Specifically, the downlink static signal is a high-frequency signal, which is difficult to separate and demodulate directly. Therefore, the downlink static signal is first converted from radio frequency to intermediate frequency band. Since the frequency of the intermediate frequency band signal is moderate, it is convenient to perform subsequent filtering, digital-to-analog / analog-to-digital conversion, signal separation and other processing. This can improve the accuracy and efficiency of signal processing, while avoiding spurious interference and signal attenuation problems that occur during high-frequency signal transmission.

[0158] More specifically, by inputting the down-converted local oscillator signal and the downlink RF signal into the mixer to perform mixing, the frequency of the downlink RF signal can be converted to the intermediate frequency band.

[0159] However, the signal obtained by directly mixing the downlink RF signal and the downconverted local oscillator signal in a mixer will contain the following two types of signal components: First, the sum frequency component of the downlink RF signal and the downconverted local oscillator signal (i.e., the component obtained by adding the frequencies of the two signals; this component has a higher frequency, so it is called the high-frequency sum frequency component, and its frequency is the sum of the frequencies of the downlink RF signal and the downconverted local oscillator signal); Second, the difference frequency component of the downlink RF signal and the downconverted local oscillator signal (i.e., the component obtained by subtracting the frequencies of the two signals; this component has a more moderate frequency, so in this embodiment it is called the intermediate frequency difference frequency component, and its frequency is the difference between the frequencies of the downlink RF signal and the downconverted local oscillator signal; its frequency range is in the intermediate frequency band, that is, tens of kHz to tens of MHz).

[0160] Because the intermediate frequency (IF) difference component has a lower frequency and falls within the IF band, it fully preserves the effective signal content such as telemetry and measurement information carried in the downlink RF signal. The high-frequency sum component, however, has a higher frequency and cannot be used for subsequent demodulation. Therefore, after mixing, it is necessary to filter out the high-frequency sum component from the resulting signal, retaining only the IF difference component. The retained IF difference component is the IF difference signal.

[0161] Specifically, the mixed signal can be input to a bandpass or lowpass filter to filter out the high-frequency and low-frequency components, thereby preserving the intermediate frequency difference signal with complete modulation information.

[0162] At this point, the signal that was originally located at a high frequency was moved to a lower mid-frequency band, while maintaining the original relative frequency interval and phase relationship.

[0163] The intermediate frequency difference signal is then demodulated to obtain the downlink valid data, as well as the static code phase and the corresponding static carrier Doppler frequency of the downlink static signal.

[0164] Specifically, the downlink static signal includes downlink measurement static signal and downlink telemetry static signal. This intermediate frequency difference signal may include both the component corresponding to the downlink measurement static signal (downlink measurement baseband signal) and the component corresponding to the downlink telemetry static signal (downlink telemetry baseband signal). Correspondingly, the downlink valid data may include downlink measurement valid data and downlink telemetry valid data.

[0165] More specifically, the downlink measurement baseband signal and the downlink telemetry baseband signal can be separated from the intermediate frequency difference signal. Then, the downlink measurement baseband signal and the downlink telemetry baseband signal are demodulated respectively to obtain the downlink measurement effective data (and its corresponding static code phase and the corresponding static carrier Doppler frequency) and the downlink telemetry effective data (and its corresponding static code phase and the corresponding static carrier Doppler frequency).

[0166] Specifically, the intermediate frequency difference signal is an analog signal, which needs to be converted from analog to digital to obtain a digital intermediate frequency difference signal. Then, the downlink measurement baseband signal is separated from the digital intermediate frequency difference signal. and downlink telemetry baseband signal The downlink measurement baseband signal and downlink telemetry baseband signal All signals are in digital form.

[0167] in, .

[0168] Where f1 is the preset downlink radio frequency local oscillator frequency mentioned above.

[0169] Specifically, since the downlink measurement RF signal and the downlink telemetry RF signal have different carrier frequencies in the original RF band, after downconversion with the preset downlink RF local oscillator frequency f1, the two signals still maintain different center frequencies in the intermediate frequency difference signal and do not overlap with each other. Therefore, signal separation can be achieved through frequency selective filtering.

[0170] The specific separation process is as follows: First, the intermediate frequency difference signal is digitally channelized and filtered. The intermediate frequency components of the corresponding downlink measurement signal and the downlink telemetry signal are extracted by two sets of bandpass filters with different center frequencies. Then, the two extracted intermediate frequency components are digitally demodulated, carrier synchronized, and pseudocode synchronized to further shift the signal from the intermediate frequency to the zero intermediate frequency baseband. After despreading and phase demodulation, the downlink measurement baseband signal and the downlink telemetry baseband signal are finally separated.

[0171] After separating the downlink telemetry baseband signal and the downlink measurement baseband signal, the test equipment first performs synchronization processing of the downlink telemetry baseband signal and the downlink measurement baseband signal, respectively.

[0172] Specifically, the testing equipment tests the downlink telemetry baseband signal. To synchronize, The intermediate frequency (IF) of the downlink telemetry baseband signal is used to track the carrier Doppler frequency in real time. and spreading pseudocode Phase recovery is performed on the local carrier and local pseudocode. The local carrier is multiplied by the input downlink telemetry baseband signal to perform carrier stripping. The local pseudocode is then XORed with the carrier-stripped downlink telemetry baseband signal to complete pseudocode stripping. After pseudocode and carrier stripping are complete, valid downlink telemetry data is extracted from the resulting downlink telemetry baseband signal. .

[0173] in, .

[0174] in, The static carrier Doppler frequency corresponding to the valid downlink telemetry data. For the corresponding spreading pseudocode, This is valid downlink telemetry data.

[0175] Correspondingly, for this downlink measurement baseband signal Synchronization is performed, and the carrier Doppler frequency is tracked in real time. and spreading pseudocode After completing the pseudocode and carrier stripping, the valid downlink measurement data is parsed. .

[0176] in, .

[0177] Furthermore, demodulation yields valid downlink measurement data. and downlink telemetry valid data Subsequently, the ground-based testing equipment used the valid measurement data from that downlink. and downlink telemetry valid data It can analyze and process data to obtain the status of the telemetry and control transponder, thereby completing the assessment of the downlink telemetry and measurement status of the telemetry and control transponder.

[0178] Specifically, the channel simulation in the signal domain, as described in the uplink transmission link simulation process above, is based on a radio frequency sampling-regeneration architecture. Specifically, the uplink signal is digitally acquired, and dynamic effects such as time delay and Doppler shift are applied in the digital domain. Then, a radio frequency signal with dynamic transmission characteristics is regenerated through digital-to-analog conversion.

[0179] However, the RF sampling-regeneration architecture requires additional high-speed analog-to-digital / digital-to-analog converters and large-capacity data processing resources. The latency introduced by the signal processing link will change the actual response timing of the telemetry and control transponder, affecting the real-time performance of the test. Furthermore, quantization noise during the RF sampling process and sampling distortion during digital-to-analog conversion will introduce additional phase jitter and spectral spurious signals, leading to a decrease in the analog accuracy of transmission delay and Doppler frequency, making it difficult to meet the high-precision delay and Doppler frequency shift testing requirements of telemetry and control transponders.

[0180] Therefore, performing dynamic Doppler simulation in the signal domain for the downlink transmission link of a telemetry and control transponder requires a complex "sampling-regeneration" architecture, which not only increases hardware costs and latency but also introduces quantization noise and phase jitter. Since the core of telemetry and control transponder testing lies in verifying the receiver's ability to capture and demodulate dynamic uplink signals, downlink dynamics are not a critical indicator. Therefore, in this embodiment, the simulation test of the downlink transmission link first adopts a static mode with a fixed Doppler frequency to significantly simplify the architecture and avoid resource waste while ensuring test effectiveness.

[0181] Then, dynamic simulation is performed in the information domain to achieve bidirectional testing of the telemetry and control transponder. Specifically, in this embodiment, when demodulating the downlink static signal, the static code phase and static carrier Doppler frequency corresponding to the downlink static signal are also obtained. The static code phase corresponding to the downlink static signal is denoted as... The static carrier Doppler frequency is denoted as Through the following step S140, based on the static code phase and static carrier Doppler frequency, a downlink dynamic Doppler simulation is performed and then transmitted to the telemetry and control transponder. In this way, the telemetry and control transponder can calculate distance, speed, etc., based on the downlink delay and downlink Doppler frequency, as well as the uplink delay and uplink Doppler frequency, thereby realizing the testing of the telemetry and control transponder's bidirectional calculation function.

[0182] Step S140: Perform dynamic Doppler simulation on the downlink measurement data in the information domain to obtain the simulated downlink measurement results, and output the downlink measurement results to the telemetry and control transponder so that the telemetry and control transponder can parse the downlink measurement results for testing.

[0183] Specifically, the downlink static signal output by the telemetry and control transponder does not undergo actual spatial propagation in the test scenario. Therefore, this downlink static signal itself does not contain the dynamic delay and Doppler frequency introduced during flight. It is equivalent to using a static mode with fixed frequency and fixed delay for the downlink transmission link, without performing dynamic simulation in the signal domain. That is, the demodulation of the downlink static signal in step S130 above yields a static carrier Doppler frequency and static delay, which only contains static or quasi-static components such as the device zero value (e.g., the fixed delay of the radio frequency cable in the telemetry and control transponder transmission link) and the frequency offset introduced by the transponder's local clock. It lacks the dynamic delay and Doppler frequency introduced during the actual flight of the aircraft.

[0184] To verify the bidirectional measurement and calculation function of the telemetry and control transponder, dynamic simulation is performed in the information domain in step S140. Specifically, this may include: calculating the downlink theoretical dynamic delay and downlink theoretical dynamic Doppler frequency corresponding to the downlink transmission link based on the simulated motion trajectory and using a preset trajectory model. The downlink theoretical dynamic delay is then superimposed on the static code phase corresponding to the downlink static signal, and the downlink theoretical dynamic Doppler frequency is superimposed on the static carrier Doppler frequency corresponding to the downlink static signal to obtain the simulated downlink measurement result.

[0185] Specifically, in missions such as two-way time synchronization between space and ground, and two-way measurement and control, the telemetry and control transponder needs to simultaneously calculate physical quantities such as two-way distance and speed on orbit based on both uplink measurement results (including time delay and Doppler frequency in the uplink transmission link) and downlink measurement results (including code phase and Doppler frequency in the downlink transmission link).

[0186] It is worth noting that code phase is a direct measure of latency. After conversion, code phase equals latency. Therefore, code phase represents the latency of the downlink transmission link.

[0187] To verify the bidirectional measurement and calculation capability of the telemetry and control transponder, in step S140, the theoretical dynamic delay of the downlink transmission link is calculated using a preset trajectory model based on the simulated motion trajectory described above. and downlink theoretical dynamic Doppler frequency The preset trajectory model is the flight trajectory model used in step S121 above, and will not be described in detail here.

[0188] Next, taking the downlink static signal measurement as an example, we will explain the theoretically calculated downlink dynamic delay. Phase with the static code obtained by demodulation in step S130 The code phase of the downlink transmission link is synthesized, and the theoretically calculated downlink dynamic Doppler frequency is then used. and static carrier Doppler frequency The carrier Doppler frequency of the downlink transmission link is obtained by synthesis, thus obtaining the simulated downlink measurement results.

[0189] Specifically, the downlink theoretical dynamic delay is superimposed on the aforementioned static code phase, and the downlink theoretical dynamic Doppler frequency is superimposed on the aforementioned static carrier Doppler frequency, which can be achieved through the following formulas: .

[0190] in, This is the code phase corresponding to the downlink transmission link. The corresponding delay of the downlink transmission link can be obtained from this code phase. The Doppler frequency corresponding to the downlink transmission link is used to obtain the downlink measurement results (including the downlink delay and Doppler frequency).

[0191] In this embodiment, the static code phase and static carrier Doppler frequency corresponding to the downlink static signal are synthesized in the information domain with the theoretical downlink dynamic delay and theoretical downlink dynamic Doppler frequency that may occur in actual flight, thereby simulating the measurement results of the downlink transmission link delay and Doppler frequency.

[0192] After receiving the downlink simulation result, the telemetry and control transponder can determine the code phase (and thus the downlink transmission link delay) and Doppler frequency based on the result. Furthermore, based on the aforementioned uplink transmission link simulation test, the transponder demodulates the uplink test simulation signal to obtain the uplink measurement result, which includes the uplink transmission link delay and Doppler frequency.

[0193] The telemetry, tracking, and command (TT&C) transponder calculates physical quantities such as the distance between the aircraft and the ground or the speed of the aircraft based on the downlink and uplink transmission link delays and Doppler frequencies. The calculation results are then used to verify whether the TT&C transponder can use the uplink and downlink measurement results to perform a comprehensive calculation of physical quantities such as distance / speed, thus achieving closed-loop verification of the TT&C transponder's bidirectional measurement and calculation function.

[0194] It is worth noting that, regarding the test dynamic simulation method for the telemetry and control transponder in this embodiment, based on the above exemplary implementations, in specific implementation, as a preferred embodiment, it is still based on... Figure 1-4 As shown, it may include, for example:

[0195] This test uses dynamic simulation methods, including simulation tests of the uplink transmission link and simulation tests of the downlink transmission link.

[0196] For the simulation test of the uplink transmission link, firstly, the uplink measurement baseband signal is generated. and uplink remote control baseband signal It is worth noting that, in this embodiment, the Doppler frequencies of multiple uplink measurement channels can be independently simulated to generate multiple uplink measurement signals. , , ...The simulation method for uplink measurement signals on all routes is consistent, and a unified method is used. express.

[0197] Next, the dynamic Doppler frequency of the uplink signal is simulated. Specifically, the calculation process of one Doppler frequency is explained as an example. A low frequency interval (e.g., 1 ms) is used as a discrete sampling point (i.e., every preset time interval), and the instantaneous radial Doppler frequency of the sky and earth corresponding to each discrete sampling point is calculated. and Doppler rate of change .

[0198] in, .

[0199] F() is a function corresponding to a known flight trajectory model (for low-Earth orbit satellites, it is usually an orbital parameter model, which can calculate the satellite's real-time velocity and acceleration), and then it is converted into Doppler frequency and Doppler rate of change.

[0200] At 2 discrete sampling points , Between these steps, a linear interpolation algorithm is used to subdivide the 1ms time window into microsteps of more than 50,000 times, each of 20ns. The Doppler frequency corresponding to each intermediate point is generated instantaneously using a simple linear formula.

[0201] After obtaining the Doppler frequency Then, based on the carrier frequency With spreading code rate The relationship can be used to obtain the real-time pseudocode Doppler frequency. : .

[0202] In the digital domain, a dynamically changing pseudocode sequence is generated in real time using an accumulator. (The pseudocode sequence corresponding to the uplink measured baseband signal) and Phase of (the pseudocode sequence corresponding to the uplink remote control baseband signal) : .

[0203] in, The initial pseudocode phase is obtained from the initial distance R0 of the aircraft. .

[0204] During the simulation, the initial distance R0 of the aircraft is represented by the initial delay of the received signal, i.e., a shift in the starting position of the pseudocode sequence; while the velocity is represented by the pseudocode Doppler frequency shift. The resulting "stretching" or "compression" of the pseudocode waveform allows for the accurate reproduction of the dynamic Doppler effect and dynamic transmission delay changes caused by aircraft motion.

[0205] Subsequently, the two uplink signals (uplink measurement baseband signal and uplink remote control baseband signal) are upconverted and combined to obtain the uplink test simulation signal of radio frequency.

[0206] After receiving the uplink test simulation signal, the telemetry and control transponder analyzes it and generates corresponding feedback. The test equipment receives this feedback and, based on the feedback and the uplink signal sent to the telemetry and control transponder, determines the transponder's performance, thus completing the test.

[0207] For the simulation test of the downlink transmission link, the downlink valid data, static code phase, and static carrier Doppler frequency corresponding to the downlink static signal are first demodulated from the received downlink static signal sent by the telemetry and control transponder. The test equipment then monitors the status of the telemetry and control transponder based on this downlink valid data.

[0208] Furthermore, the test equipment also performs dynamic Doppler simulation in the information domain based on the static code phase and static carrier Doppler frequency to obtain simulated downlink measurement results, which are then output to the telemetry and control transponder. This allows the telemetry and control transponder to calculate physical quantities such as distance and speed based on the downlink measurement results and the aforementioned uplink measurement results, thereby testing the bidirectional measurement and calculation function of the telemetry and control transponder.

[0209] In the preferred embodiment of the above test dynamic simulation method for the telemetry and control transponder, the specific implementation of each step can still be found in the descriptions of the above exemplary embodiments, and the beneficial effects brought about by the design of each step in this preferred embodiment can also be found in the descriptions of the above exemplary embodiments.

[0210] The test dynamic simulation method for the telemetry and control transponder of this application uses simulated motion trajectory and uplink frequency parameters to simulate the Doppler frequency that dynamically changes due to the motion of the aircraft in the space-to-ground transmission link. After performing Doppler frequency dynamic modulation processing on each uplink baseband signal, an uplink test simulation signal is obtained, and the telemetry and control transponder analyzes the uplink test simulation signal to perform uplink testing.

[0211] By simulating the motion trajectory to generate uplink test simulation signals that closely resemble the actual ground-to-ground transmission link, the channel changes caused by the aircraft's motion in the uplink transmission link can be accurately reproduced, thereby improving the reliability of the test.

[0212] Furthermore, in this embodiment, not only can the uplink transmission link be simulated and tested, but the downlink transmission link can also be simulated and tested, realizing integrated simulation and testing of uplink and downlink transmission links.

[0213] On the one hand, this application adopts a static transmission method in the downlink transmission link, receiving a downlink static signal instead of using hardware simulation links for dynamic simulation. This avoids problems such as quantization noise, phase jitter, increased hardware cost, and increased system latency introduced by the RF sampling and regeneration architecture in hardware simulation links, thereby ensuring a high signal-to-noise ratio and high stability of the downlink signal receiving channel.

[0214] On the other hand, after receiving the downlink static signal, dynamic simulation is then performed in the information domain. That is, in the simulation test of the downlink transmission link, the dynamic simulation is not performed in the signal domain, but in the information domain, to obtain downlink measurement results that are equivalent to the dynamic simulation in the signal domain and contain the complete flight dynamics. Software calculation replaces the complex hardware simulation link. When the telemetry and control transponder receives this downlink measurement result, it can use the downlink measurement result (downlink transmission link delay and Doppler frequency) and the uplink delay and uplink Doppler frequency corresponding to the uplink test simulation signal to calculate physical quantities such as distance and speed, thereby verifying the bidirectional measurement and calculation capability of the telemetry and control transponder.

[0215] In other words, this application can not only test the dynamic uplink acquisition and adaptation capabilities of the ground-based telemetry and control transponder, but also provide downlink measurement results for bidirectional measurement calculation through dynamic simulation of the information domain, thereby improving the coverage of ground testing and thus enhancing the reliability of the aerospace telemetry and control system.

[0216] An embodiment of the second aspect of this application provides a dynamic simulation system for testing a telemetry and control transponder. The dynamic simulation system for testing a telemetry and control transponder in this embodiment includes an uplink transmission link simulation test unit and may also include a downlink transmission link simulation test unit.

[0217] The uplink transmission link simulation test unit includes an acquisition module and an uplink modulation module.

[0218] The acquisition module acquires the uplink baseband signals used for simulation testing, as well as the uplink frequency parameters and the simulated motion trajectory of the telemetry and control transponder. The uplink modulation module performs Doppler frequency dynamic modulation on each uplink baseband signal based on the uplink frequency parameters and the simulated motion trajectory to obtain the uplink test simulation signal, which is then output to the telemetry and control transponder, enabling the transponder to perform uplink testing based on the uplink test simulation signal.

[0219] The downlink transmission link simulation test unit in this embodiment may include a downlink demodulation module and a downlink simulation test module.

[0220] The downlink demodulation module is used to demodulate the downlink static signal received from the telemetry and control transponder to obtain the downlink measurement data corresponding to the downlink static signal. The downlink simulation test module is used to perform dynamic Doppler simulation on the downlink measurement data in the information domain to obtain the simulated downlink measurement result, and output the downlink measurement result to the telemetry and control transponder, so that the telemetry and control transponder can parse the downlink measurement result for testing.

[0221] The dynamic simulation system for testing the telemetry and control transponder in this embodiment can not only simulate the uplink transmission link by simulating the motion trajectory, thereby generating uplink test simulation signals that closely resemble the characteristics of real-world transmission links to achieve uplink dynamic simulation testing and improve the reliability of telemetry and control transponder testing, but also evaluate the downlink telemetry and measurement status of the telemetry and control transponder by using the downlink static signals sent by the telemetry and control transponder.

[0222] Furthermore, this embodiment also performs dynamic Doppler simulation of the downlink measurement results in the information domain and outputs them to the telemetry and control transponder, enabling the telemetry and control transponder to calculate distance, speed, etc. based on the downlink measurement results and in combination with the downlink measurement results (time delay and Doppler frequency) obtained by demodulating the uplink test simulation signal, thereby realizing the test of the bidirectional measurement function of the telemetry and control transponder.

[0223] The above are merely some embodiments of this application and are not intended to limit this application. The technical features or structures in the foregoing different embodiments can be arbitrarily combined to form other specific technical solutions as needed. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the protection scope of the claims of this application.

Claims

1. A dynamic simulation method for testing a telemetry and control transponder, characterized in that, include: Acquire the uplink baseband signals used for simulation testing, as well as the uplink frequency parameters and the simulated motion trajectory of the telemetry and control transponder; Based on the uplink frequency parameters and the simulated motion trajectory, Doppler frequency dynamic modulation is performed on each of the uplink baseband signals to obtain an uplink test simulation signal, which is then output to the telemetry and control transponder, enabling the telemetry and control transponder to perform uplink tests based on the uplink test simulation signal. The downlink measurement data corresponding to the downlink static signal is obtained by demodulation from the downlink static signal sent by the received telemetry and control transponder; The downlink measurement data is subjected to dynamic Doppler simulation in the information domain to obtain simulated downlink measurement results, and the downlink measurement results are output to the telemetry and control transponder, so that the telemetry and control transponder can parse the downlink measurement results for testing.

2. The test dynamic simulation method according to claim 1, characterized in that, The process involves dynamically modulating each uplink baseband signal using Doppler frequency based on the uplink frequency parameters and the simulated motion trajectory to obtain an uplink test simulation signal, which is then output to the telemetry and control transponder. This enables the telemetry and control transponder to perform uplink testing based on the uplink test simulation signal, including: Based on the uplink frequency parameters and the simulated motion trajectory, calculate the dynamically changing Doppler frequency in the ground-to-ground transmission link due to the movement of the telemetry and control transponder; Based on the Doppler frequency, each of the uplink baseband signals is modulated; The modulated uplink baseband signals are upconverted and combined to obtain radio frequency uplink test simulation signals, which are then sent to the telemetry and control transponder so that the telemetry and control transponder performs tests based on the uplink test simulation signals.

3. The test dynamic simulation method for a telemetry and control transponder according to claim 2, characterized in that, The calculation of the dynamically changing Doppler frequency in the ground-to-ground transmission link due to the movement of the telemetry and control transponder includes: A discrete sampling point is taken at preset time intervals in the simulated motion trajectory; Based on the simulated motion trajectory, calculate the Doppler frequency and the rate of change of Doppler frequency corresponding to each discrete sampling point; Based on the Doppler frequency and Doppler frequency change rate corresponding to each discrete sampling point, linear interpolation is performed between two adjacent discrete sampling points to obtain each intermediate point and the Doppler frequency corresponding to each intermediate point.

4. The test dynamic simulation method for a telemetry and control transponder according to claim 2, characterized in that, The uplink frequency parameters include the uplink carrier frequency and the spreading code rate; The modulation processing of each of the uplink baseband signals includes: Based on the uplink carrier frequency, the spreading code rate, and the Doppler frequency corresponding to each time moment, calculate the pseudocode Doppler frequency at each time moment; Calculate the phase of the pseudocode sequence at each time step based on the pseudocode Doppler frequency at each time step; Based on the phase of the pseudocode sequence, the pseudocode sequence is determined; Based on the preset carrier frequency and the Doppler frequency corresponding to each time moment, a carrier signal with dynamic Doppler is determined; The uplink baseband signal is modulated based on the carrier signal and the pseudocode sequence.

5. The test dynamic simulation method for a telemetry and control transponder according to claim 4, characterized in that, The phase of the pseudocode sequence is calculated using the following formula: ； ； in, The phase of the pseudocode sequence, Let C be the initial pseudocode phase and C be the speed of light. The initial distance for the telemetry and control transponder. The spreading code rate is... This is the pseudocode Doppler frequency.

6. The test dynamic simulation method for a telemetry and control transponder according to claim 4, characterized in that, The modulation processing of the uplink baseband signal based on the carrier signal and the pseudocode sequence includes: Determine the uplink information data frame carried by the uplink baseband signal; The uplink information data frame is subjected to direct sequence spread spectrum modulation processing using the pseudocode sequence to obtain the spread spectrum modulated uplink baseband signal. Using the carrier signal, the spread spectrum modulated uplink baseband signal is subjected to carrier modulation processing to obtain the modulated uplink baseband signal.

7. The test dynamic simulation method for a telemetry and control transponder according to claim 2, characterized in that, The uplink baseband signal includes an uplink measurement baseband signal and an uplink remote control baseband signal; The step of upconverting and combining the modulated uplink baseband signals to obtain the radio frequency uplink test simulation signal includes: The modulated uplink measurement baseband signal and the modulated uplink remote control baseband signal are respectively subjected to pulse shaping processing to obtain a first digital intermediate frequency sequence and a second digital intermediate frequency sequence; The first digital intermediate frequency sequence and the second digital intermediate frequency sequence are linearly superimposed and combined to obtain a composite data intermediate frequency signal. The composite data intermediate frequency signal is converted from digital to analog to obtain an analog intermediate frequency signal; The simulated intermediate frequency signal is mixed with a preset radio frequency local oscillator signal to obtain the uplink test simulated signal of the radio frequency.

8. The test dynamic simulation method for a telemetry and control transponder according to claim 1, characterized in that, The step of demodulating the downlink measurement data corresponding to the downlink static signal received from the telemetry and control transponder includes: Receive the downlink static signal sent by the telemetry and control transponder; A down-conversion local oscillator signal is generated based on a preset down-frequency radio frequency local oscillator frequency; The down-conversion local oscillator signal and the down-current static signal are input to a mixer for mixing to obtain a mixed signal; The mixed signal is filtered to retain the intermediate frequency difference frequency component, thus obtaining the intermediate frequency difference frequency signal. Demodulate the intermediate frequency difference signal to obtain downlink valid data, as well as the static code phase and the corresponding static carrier Doppler frequency of the downlink static signal; The downlink measurement data includes the static code phase corresponding to the downlink static signal and the corresponding static carrier Doppler frequency.

9. The test dynamic simulation method for a telemetry and control transponder according to claim 8, characterized in that, The step of performing dynamic Doppler simulation on the downlink measurement data in the information domain to obtain the simulated downlink measurement results includes: Based on the simulated motion trajectory, the downlink theoretical dynamic delay and downlink theoretical dynamic Doppler frequency corresponding to the downlink transmission link are calculated using a preset trajectory model. The downlink theoretical dynamic delay is superimposed on the static code phase, and the downlink theoretical dynamic Doppler frequency is superimposed on the static carrier Doppler frequency to obtain the simulated downlink measurement result.

10. A dynamic simulation system for testing a telemetry and control transponder, characterized in that, include: The acquisition module is used to acquire the uplink baseband signals used for simulation testing, as well as the uplink frequency parameters and the simulated motion trajectory of the telemetry and control transponder; The uplink modulation module is used to perform Doppler frequency dynamic modulation on each of the uplink baseband signals based on the uplink frequency parameters and the simulated motion trajectory to obtain an uplink test simulation signal, which is then output to the telemetry and control transponder so that the telemetry and control transponder performs uplink testing based on the uplink test simulation signal. The downlink demodulation module is used to demodulate the downlink static signal received from the telemetry and control transponder to obtain the downlink measurement data corresponding to the downlink static signal; The downlink simulation test module is used to perform dynamic Doppler simulation on the downlink measurement data in the information domain to obtain the simulated downlink measurement results, and output the downlink measurement results to the telemetry and control transponder, so that the telemetry and control transponder can parse the downlink measurement results for testing.

Images