Demodulation tracking processing system and method for deep-space high-dynamic low-bit-rate signals
By introducing a weighted matched filter and a multi-channel coarse-fine estimation deep space high dynamic low bit rate signal demodulation and tracking system, the problem of demodulation and tracking of high dynamic and low bit rate signals in deep space exploration has been solved, and high-precision and stable signal demodulation has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies struggle to effectively handle demodulation and tracking of high-dynamic, low-code-rate signals in deep space exploration, especially when telemetry data transmission rates are below 10 bps. This results in significant demodulation losses, excessive sampling rates and storage pressure, and the contradiction between carrier loop acquisition range and error fluctuations remains unresolved.
By employing a weighted matched filter, multi-channel coarse and fine estimation combined processing, and small sampling high-frequency clock multiplexing demodulation and tracking method, high-precision demodulation of deep space high dynamic low code rate signals is achieved through baseband I/Q signal reception, carrier processing, multi-channel coarse and fine estimation, and optimal channel selection.
It significantly improves the stability and accuracy of demodulation and tracking in deep space communication, resolves the contradiction between acquisition range and error fluctuation in low signal-to-noise ratio and low code rate scenarios, and reduces demodulation loss and sampling rate pressure.
Smart Images
Figure CN121792284A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a deep space high dynamic low code rate signal demodulation and tracking processing system and method, belonging to the field of spacecraft integrated testing technology. Background Technology
[0002] As the sole channel and link for communication with the probe, telemetry, tracking, and command (TT&C) data transmission plays a crucial role in deep space exploration, establishing communication links and transmitting remote control commands, telemetry data, and image signals. Compared to near-Earth orbit TT&C communication systems, deep space exploration communication involves longer distances, greater latency, and limited bandwidth. These limitations result in deep space communication characterized by low code rates and a large Doppler dynamic range, making each frame of communication data extremely valuable. With the continuous development of my country's deep space probe technology, higher and newer technical requirements are placed on ground equipment to ensure the most comprehensive and accurate collection of telemetry data returned by deep space probes. Therefore, a reliable demodulation and tracking processing method for the high dynamic range and low code rate signals of deep space transponders is urgently needed.
[0003] The main technical challenges currently lie in the following aspects: 1) Deep space telemetry data transmission rates are as low as below 10 bps, and the demodulation threshold Eb / N0 has only ≤1.2 dB of demodulation loss margin compared to the theoretical value. In practical systems, due to losses in various stages, performance often cannot reach the theoretical limit. Traditional baseband demodulation losses cannot meet this requirement, necessitating improvements to demodulator performance to reduce demodulation losses. 2) Based on the fundamental principles of Fast Fourier Transform (FFT), the amount of effective data in the intermediate frequency spectrum required for carrier acquisition cannot be too low. Considering the proportional relationship between sampling rate, effective working time, and effective data volume, increasing the effective data volume with a fixed effective working time inevitably increases the number of sampling points. For high-dynamic, low-bit-rate scenarios, the short effective working time necessitates a significant increase in the sampling factor. With this substantial increase in the sampling factor over a short period, storage and processing pressures rise sharply, making it difficult for traditional baseband FPGAs to adapt to such a significant performance improvement. 3) For demodulation and tracking loops, there is a trade-off between acquisition range and error fluctuation. In low signal-to-noise ratio (SNR) and low bit rate scenarios, highly stable carrier loop tracking is required. To achieve narrowband carrier tracking of high-dynamic, weak signals in multi-mode telemetry data transmission, an extremely narrow bandwidth carrier phase-locked loop (PLL) is needed to improve the loop's SNR and reduce random error fluctuations in the loop output. However, this reduces the acquisition range of the carrier loop, which contradicts the requirement to track Doppler dynamics. Summary of the Invention
[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a demodulation and tracking processing system and method for deep space high dynamic and low code rate signals. By introducing a weighted matched filter, multi-channel coarse and fine estimation joint processing, and small sampling high-multiple clock multiplexing demodulation and tracking, the demodulation and tracking function of deep space high dynamic and low code rate signals is completed.
[0005] The technical solution of this invention is: A deep-space high-dynamic low-code-rate signal demodulation and tracking processing system includes a baseband I / Q signal receiver, a carrier processing module, a multi-channel coarse and fine estimation module, a small-sampling high-frequency multiplexing clock multiplexing module, and an optimal channel selection module; The baseband I / Q signal receiver receives the down-converted baseband I / Q signal and determines the baseband I / Q signal parameters, including the roll-off factor. symbol rate ; The carrier processing module includes a carrier tracking loop, a weighted matched filter, and a code synchronizer. The carrier tracking loop captures and tracks the baseband I / Q signal and outputs the carrier tracking signal to the weighted matched filter and the optimal channel selection module. The weighted matched filter calculates weighting coefficients based on the baseband I / Q signal parameters and the carrier tracking signal, and outputs the weighted optimized signal to the code synchronizer. The code synchronizer performs code synchronization on the weighted optimized signal and then transmits it to the multi-channel coarse and fine estimation module. The multi-channel coarse estimation module divides the frequency offset range of the input signal into... For each sub-interval, the optimal channel's carrier frequency offset is output through multi-channel coarse estimation. Calculate the Doppler rate of change and adjust the carrier frequency offset. The data is transmitted to a small-sample, high-frequency clock multiplexing module to convert the Doppler change rate. Transmitted to the optimal channel selection module; The small-sampling high-frequency clock multiplexing module is based on the carrier frequency offset. Multiple Doppler rate of change compensation channels are generated at multiple sampling rates to locate spectral peaks, dynamically adjust the number of sampling points, and transmit the sampling results to the optimal channel selection module. The optimal channel selection module is based on sampling results and Doppler change rate. The carrier tracking signal is dynamically compensated for phase, the carrier tracking loop gain is updated, and the final demodulation result of the deep space high dynamic low code rate signal is output.
[0006] Furthermore, the weighted matched filter is based on the roll-off factor of the baseband I / Q signals. and symbol rate The carrier tracking signal aims to maximize the spectral matching degree. It calls the pre-stored coefficient table, dynamically selects the weighting coefficients of the matched filter, and outputs the weighted and optimized signal.
[0007] Furthermore, the method for multi-channel coarse estimation in the multi-channel coarse estimation module is as follows: Using 1 / N The sampling rate and high-harmonic clock are used to perform spectral analysis on the signals of each channel, detecting the position of the maximum spectral peak, suppressing transition points, and providing a coarse estimate of the output carrier frequency and demodulation performance indicators for each channel; among these... N Number of channels; Based on demodulation performance metrics, channels with signal-to-noise ratio changes exceeding a set threshold and phase noise variance below a set threshold are selected. The carrier offset range of these channels is then reduced to 1 / N .
[0008] Furthermore, the carrier tracking loop acquires and tracks the baseband I / Q signals and outputs a carrier tracking signal. The specific method is as follows: Initialization signal for the baseband I / Q signal output carrier demodulation loop; A frequency-locked loop is used to capture the carrier demodulation loop initialization signal, and the captured Doppler residual is tracked quickly to output a carrier tracking signal containing Doppler residual information. The Doppler rate of change of the carrier tracking signal is estimated, and a carrier phase-locked loop is used to dynamically adjust the loop gain based on the Doppler rate of change, update the carrier tracking loop parameters, dynamically compensate for Doppler changes, and output a high-precision carrier tracking signal.
[0009] Furthermore, based on the baseband I / Q signal, the carrier demodulation loop initialization signal is output. Specifically, the carrier tracking loop has multiple loops to detect the baseband I / Q signal. If a residual carrier is detected, the residual carrier phase-locked loop or a combination loop is activated; if a suppressed carrier is detected, the maximum a posteriori probability loop is activated; and finally, the adapted carrier tracking loop initialization signal is output.
[0010] The demodulation and tracking processing method based on the deep space high dynamic low bit rate signal demodulation and tracking processing system includes: S1: Based on the input deep space high dynamic low code rate signal baseband I / Q signal, output the adapted carrier tracking loop initialization signal; S2: Based on the carrier tracking loop initialization signal, a frequency-locked loop is used to quickly track the Doppler residual after carrier acquisition, and a carrier signal containing Doppler residual information is output. S3: Estimate the Doppler rate of change of the carrier signal using a Kalman filter; S4: Based on the carrier signal, a carrier phase-locked loop is used to dynamically adjust the loop gain based on the Doppler rate of change, update the carrier tracking loop parameters, dynamically compensate for Doppler changes, and output a high-precision carrier tracking signal; S5: Obtain the weighting coefficients of the matched filter based on the roll-off factor and symbol rate of the baseband I / Q signal; weight the high-precision carrier tracking signal to obtain the optimized signal; S6: Perform multi-channel processing on the optimized signal and output the coarse estimation results for each channel, including the coarse estimate of the carrier frequency, the change in signal-to-noise ratio for each channel, and the variance of phase noise for each channel. S7: Based on the coarse estimation results of each channel, select the optimal channel and compress the carrier offset range of the optimal channel; S8: Based on the carrier deviation range of the optimal channel, compensate for the phase of the high-precision carrier tracking signal and output the high-precision demodulation result of the deep space high dynamic low code rate signal.
[0011] Furthermore, step S6 specifically includes: 1) Channel partitioning: Divide the optimized signal into equal channels. Parallel access roads; 2) Spectrum detection: using The sampling rate and high-frequency clock are used to perform spectrum analysis on each signal to detect the location of the maximum spectral peak. 3) Sampling point optimization: based on phase noise variance Determine whether to dynamically add or remove sampling points; 4) Jump point suppression: Weighted processing of the first / last sampling points of the symbol during mid-phase / in-phase integration; 5) Channel output: Coarse estimate of carrier frequency for each channel. and demodulation performance indicators ,in For the first Changes in the signal-to-noise ratio of the road channel.
[0012] Furthermore, in step S4, the method for dynamically adjusting the loop gain based on the Doppler rate of change is as follows:
[0013] Furthermore, in step S2, the acquisition range for carrier acquisition is... .
[0014] Further, in step S7, based on the coarse estimation results of each channel, channels whose signal-to-noise ratio change exceeds a set change threshold and whose phase noise variance is lower than a set variance threshold are selected, thus compressing the carrier offset range of the channels to... .
[0015] The advantages of this invention compared to the prior art are: (1) This invention introduces a weighted matched filter into the carrier tracking loop, and its weighting coefficients can be dynamically and adaptively adjusted according to parameters such as the roll-off coefficient of the shaping filter at the modulation end and the symbol rate. Through the optimal weighting coefficient design, the advantages of the filter's spectral characteristics are fully utilized. Especially for deep space low symbol rate signals, this invention significantly suppresses the calculation jitter at symbol transitions and effectively improves loop stability.
[0016] (2) This invention proposes a multi-channel coarse-fine joint estimation architecture, which quickly converges the carrier deviation range through coarse estimation of multiple parallel channels, and then achieves high-precision tracking by combining it with fine estimation. This scheme breaks through the inherent contradiction between acquisition range and estimation error fluctuation in low signal-to-noise ratio and low symbol rate scenarios in existing technologies.
[0017] (3) This invention is based on low sampling rate high-frequency clock multiplexing and demodulation. It uses a high-frequency clock to detect the spectral characteristic lines of each signal and selects the branch with the best Doppler frequency shift rate compensation performance to simultaneously obtain the carrier frequency estimation result. Thus, under high sampling rate conditions, only a small amount of effective data is needed to complete the carrier frequency estimation, completely overcoming the problem of estimation failure caused by insufficient effective data in low signal-to-noise ratio and low symbol rate scenarios. Attached Figure Description
[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a block diagram of the link structure according to an embodiment of the present invention; Figure 2 This is a block diagram of the multi-channel coarse-fine estimation module in an embodiment of the present invention; Figure 3 This is a block diagram of a small-sampling high-frequency clock module according to an embodiment of the present invention. Detailed Implementation
[0019] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
[0020] This invention proposes a deep-space high-dynamic low-bit-rate signal demodulation and tracking processing system. Its overall link consists of five core modules arranged in data flow order, with each module interacting with the others through clearly defined parameters. 1) Baseband I / Q signal receiver: Receives the baseband I / Q signal after RF down-conversion and determines the signal roll-off factor. symbol rate Parameters; 2) Weighted matched filter: For deep space signals with low code rate and small roll-off factor, this invention introduces a weighted matched filter between the carrier tracking loop output and the code synchronizer input. The weighted coefficients are calculated based on the modulation end shaping filter and the receiver matching filter to receive the baseband I / Q signal parameters, thereby reducing loop jitter and demodulation loss, and transmitting the data to the multi-channel coarse and fine estimation module.
[0021] 3) Multi-channel coarse and fine estimation module, such as Figure 2 As shown, the input signal frequency offset range is divided into... Select signal-to-noise ratio for each sub-interval (This criterion can be modified) for the channel, linear interpolation yields the carrier frequency offset. Calculate the Doppler rate of change By combining multi-channel coarse estimation and total channel fine estimation, high-precision compensation of the carrier frequency signal is achieved, improving carrier demodulation and tracking efficiency. This module will... Transmitted to the small-sampling high-frequency clock multiplexing module, Transmitted to the optimal channel selection module.
[0022] 4) Small sampling high-frequency clock multiplexing module, such as Figure 3 As shown, the sampling rate is increased by 8 times (this parameter can be changed) to Eight Doppler rate of change compensation channels are generated to locate spectral peaks and dynamically adjust the number of sampling points. The results are then transmitted to the optimal channel selection module.
[0023] 5) Optimal channel selection module: dynamically compensates carrier phase, updates loop gain, and outputs the final demodulation result.
[0024] Methods for demodulating and tracking deep space high-dynamic low-bit-rate signals based on the overall link, such as... Figure 1 As shown, it includes: S1: Dynamic switching of carrier tracking loop, automatically selecting demodulation architecture based on signal modulation, solving the carrier type adaptation problem.
[0025] The raw received signal (PM modulated signal) is detected, and the processing method is selected based on the detection result: If a residual carrier (PCM / PM signal) is detected, activate the residual carrier phase-locked loop (PLL) or a combination loop; If a suppressed carrier (BPSK / QPSK / OQPSK signal) is detected, the maximum a posteriori probability loop (MAP loop) is activated.
[0026] After processing, an adapted carrier tracking loop initialization signal is output.
[0027] S2: Carrier acquisition stage (frequency-locked loop tracking), which solves the problem of initial frequency offset acquisition in high dynamic scenarios.
[0028] Based on the carrier tracking loop initialization signal output by S1, a frequency-locked loop is used to quickly track the Doppler residual after carrier acquisition, and the carrier signal after tracking by the frequency-locked loop is output. The carrier signal contains Doppler residual information.
[0029] S3: Accurate estimation of Doppler rate of change provides key parameters for subsequent loop assisted operation. Based on the carrier signal output by S2, the carrier frequency offset is adjusted using a Kalman filter. Perform high-precision estimation (error ≤ 0.05 Hz / s) and output Doppler rate of change estimate. :
[0030] S4: Carrier loop assisted tracking (improves tracking accuracy in high dynamic scenes) Based on the carrier signal output by S2 and the signal output by S3 Employing a carrier phase-locked loop, based on Dynamically adjust loop gain This completes dynamic compensation for Doppler variations and outputs a high-precision carrier tracking signal. Specifically:
[0031] In the formula, For the initial , for Maximum value.
[0032] Update the carrier tracking loop parameters, dynamically compensate for Doppler variations, and output a high-precision carrier tracking signal.
[0033] S5: Dynamic configuration of weighted matched filters to solve low bit rate loop jitter issues. Based on the carrier tracking signal output by S4 and the real-time detected roll-off factor symbol rate To maximize the spectral matching degree (avoiding white noise introduced by the traditional integration method), the weighting coefficients of the matched filter are dynamically selected: like and Call the pre-stored coefficient table ( , The pre-stored coefficient table input is the roll-off factor. symbol rate The output is the filter weighting coefficients. The specific weighting coefficients were obtained during the initial debugging of the link.
[0034] The output signal is weighted and optimized, which can suppress jitter of phase detection error at symbol transition points by ≥40%.
[0035] S6: Multi-channel coarse and fine combined processing (N parallel channels) to resolve the contradiction between capture range and accuracy.
[0036] 1) Divide the weighted optimized signal output by S5 into equal parts. Parallel channel ( Typical value Each channel operates independently: 2) Spectrum detection: using a 1 / N sampling rate + high-frequency clock ( , Perform spectrum analysis on each signal (at the original frequency); detect the position of the maximum spectral peak; 3) Sampling point optimization: based on phase noise variance Determine whether to dynamically increase or decrease sampling points; 4) Jump point suppression: During mid-phase / in-phase integration, the first / last sampling points of the symbol are weighted (weighting function: ); 5) Channel output: Coarse estimate of carrier frequency for each channel. and demodulation performance indicators ,in This represents the change in signal-to-noise ratio for each channel.
[0037] The final output is a coarse estimate of the N channels. .
[0038] S7: Channel optimization and deviation range reduction solve the problem of multi-channel result fusion.
[0039] Based on the N-channel output of S6, the criterion is first determined: selection. and First, the optimal channel has a reduced carrier offset range; second, the offset range is reduced to [value missing]. And output (e.g.: At that time, the scope was reduced to ).
[0040] S8: Carrier frequency high-precision compensation and demodulation output, completing closed-loop demodulation tracking.
[0041] Based on the optimal channel deviation range output by S7 and the high-precision carrier signal output by S4, coarse and fine co-compensation is performed: multi-channel coarse estimation (S7 result) + total channel fine estimation (S4 result); noise is further suppressed by improving the carrier tracking loop, resulting in high-precision demodulation results for deep space high-dynamic low-code-rate signals, with a carrier frequency estimation error not exceeding [percentage missing]. .
[0042] The beneficial effects of this invention include: 1) Introduce a weighted matched filter in the demodulation and tracking link. Based on quantization error analysis of the carrier tracking performance, filter performance, and code synchronizer performance of the baseband equipment, it was found that the signal undergoes shaping filtering with different roll-off factors at the modulation end. The degree of beamforming is determined by the signal. In traditional baseband receivers, demodulation typically uses integration over the symbol period, which generates white noise and introduces errors. In deep-space high-dynamic, low-code-rate signals, the roll-off factor is generally small, making loop jitter more pronounced. Therefore, this invention introduces a weighted matched filter into the demodulation tracking link. The weighting coefficients are designed separately based on different roll-off factors and code rates to achieve the optimal solution for loop jitter in the overall link, reducing system demodulation losses.
[0043] By introducing a weighted matched filter, the parameters of the matched filter can be adjusted according to the different roll-off coefficients of the shaping filter at the modulation end and the different code rates, so as to better match the transmitted signal. Furthermore, by optimally selecting the weighting coefficients, the spectral characteristics of the filter can be maximized, achieving better signal matching without losing spectral information. Especially at low code rates, significant jitter occurs in the phase detection error calculation at symbol transition points; using a weighted matched filter can significantly reduce this jitter, further improving loop stability.
[0044] 2) Multi-channel coarse and fine estimation combined processing To address the conflicting challenges of acquisition range and error fluctuation under low signal-to-noise ratio and low bit rate conditions, this invention builds upon existing carrier frequency precise estimation methods. a) By using multiple parallel channels, the carrier offset range can be further reduced, which is beneficial for carrier tracking (e.g., if N channels are used, the frequency offset range that each channel needs to capture is reduced to 1 / N). b) For the results of multi-channel processing, reasonably design and add locking criteria, select the channel with the best demodulation effect, and further reduce the carrier deviation range; c) By combining multi-channel coarse estimation and total channel fine estimation, high-precision compensation of the carrier frequency signal is achieved, thereby improving carrier demodulation and tracking efficiency.
[0045] 3) Small sampling, high-harmonic clock multiplexing demodulation For high dynamic and low bit rate scenarios, it is necessary to significantly increase the sampling multiple in a short period of time. Traditional basebands are unable to adapt to such a sharp increase in storage and processing pressure. This invention uses a small sampling high-multiplication clock method to realize the detection and analysis of multiple frequency bands and find the location of the maximum spectral peak.
[0046] To address the challenge of limited effective data for estimation in low-bitrate, low-signal-to-noise ratio environments, this invention: a) Combining with 2), the method of slotting the Doppler rate of change is used to set multiple Doppler rate of change compensation channels, thereby covering a larger Doppler change space; b) Use a high-frequency clock to detect the carrier frequency characteristic spectral lines of each signal, select the branch with better Doppler rate of change compensation, and obtain the carrier frequency estimation result, thereby completing the carrier frequency estimation with a small amount of effective data under high sampling rate; c) To address the problem of excessively large short-time sampling multiples, when performing coarse and fine carrier frequency estimation in 3), based on the original quantitative error judgment results, the use of interpolation operations is reduced, and sampling points are added / subtracted to complete the extraction and correction of carrier synchronization error under small sampling rates. d) When integrating in phase and in phase, the first and last sampling points of the symbol are weighted to avoid the influence of high noise interference on the 0 / 1 transition position, and further improve the accuracy of frequency estimation at low sampling rate. e) By improving the DTTL loop, the impact of noise on the loop can be reduced to a certain extent, further improving timing synchronization under conditions of low sampling rate and low signal-to-noise ratio.
[0047] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.
Claims
1. A deep-space high-dynamic low-bit-rate signal demodulation and tracking processing system, characterized in that, It includes a baseband I / Q signal receiver, a carrier processing module, a multi-channel coarse and fine estimation module, a small sampling high-frequency clock multiplexing module, and an optimal channel selection module; The baseband I / Q signal receiver receives the down-converted baseband I / Q signal and determines the baseband I / Q signal parameters, including the roll-off factor. symbol rate ; The carrier processing module includes a carrier tracking loop, a weighted matched filter, and a code synchronizer; the carrier tracking loop captures and tracks the baseband I / Q signal and outputs the carrier tracking signal to the weighted matched filter and the optimal channel selection module. The weighted matched filter calculates weighting coefficients based on baseband I / Q signal parameters and carrier tracking signal, and outputs the weighted optimized signal to the code synchronizer; the code synchronizer performs code synchronization on the weighted optimized signal and then transmits it to the multi-channel coarse and fine estimation module. The multi-channel coarse estimation module divides the frequency offset range of the input signal into... For each sub-interval, the optimal channel's carrier frequency offset is output through multi-channel coarse estimation. Calculate the Doppler rate of change and adjust the carrier frequency offset. The data is transmitted to a small-sample, high-frequency clock multiplexing module to convert the Doppler change rate. Transmitted to the optimal channel selection module; The small-sampling high-frequency clock multiplexing module is based on the carrier frequency offset. Multiple Doppler rate of change compensation channels are generated at multiple sampling rates to locate spectral peaks, dynamically adjust the number of sampling points, and transmit the sampling results to the optimal channel selection module. The optimal channel selection module is based on sampling results and Doppler change rate. The carrier tracking signal is dynamically compensated for phase, the carrier tracking loop gain is updated, and the final demodulation result of the deep space high dynamic low code rate signal is output.
2. The deep space high dynamic low code rate signal demodulation and tracking processing system according to claim 1, characterized in that, The weighted matched filter is based on the roll-off factor of the baseband I / Q signals. and symbol rate The carrier tracking signal aims to maximize the spectral matching degree. It calls the pre-stored coefficient table, dynamically selects the weighting coefficients of the matched filter, and outputs the weighted and optimized signal.
3. The deep space high dynamic low code rate signal demodulation and tracking processing system according to claim 1, characterized in that, The method for multi-channel coarse estimation in the multi-channel coarse estimation module is as follows: Using 1 / N The sampling rate and high-harmonic clock are used to perform spectral analysis on the signals of each channel, detecting the position of the maximum spectral peak, suppressing transition points, and providing a coarse estimate of the output carrier frequency and demodulation performance indicators for each channel; among these... N Number of channels; Based on demodulation performance metrics, channels with signal-to-noise ratio changes exceeding a set threshold and phase noise variance below a set threshold are selected. The carrier offset range of these channels is then reduced to 1 / N .
4. The deep space high dynamic low code rate signal demodulation and tracking processing system according to claim 1, characterized in that, The carrier tracking loop captures and tracks the baseband I / Q signals and outputs a carrier tracking signal. The specific method is as follows: Initialization signal for the baseband I / Q signal output carrier demodulation loop; A frequency-locked loop is used to capture the carrier demodulation loop initialization signal, and the captured Doppler residual is tracked quickly to output a carrier tracking signal containing Doppler residual information. The Doppler rate of change of the carrier tracking signal is estimated, and a carrier phase-locked loop is used to dynamically adjust the loop gain based on the Doppler rate of change, update the carrier tracking loop parameters, dynamically compensate for Doppler changes, and output a high-precision carrier tracking signal.
5. The deep space high dynamic low code rate signal demodulation and tracking processing system according to claim 1, characterized in that, The carrier demodulation loop initialization signal is output based on the baseband I / Q signal. Specifically, the carrier tracking loop has multiple loops to detect the baseband I / Q signal. If a residual carrier is detected, the residual carrier phase-locked loop or a combination loop is activated. If a suppressed carrier is detected, the maximum a posteriori probability loop is activated. Finally, the adapted carrier tracking loop initialization signal is output.
6. The demodulation and tracking processing method based on the deep space high dynamic low code rate signal demodulation and tracking processing system as described in claim 1, characterized in that, include: S1: Based on the input deep space high dynamic low code rate signal baseband I / Q signal, output the adapted carrier tracking loop initialization signal; S2: Based on the carrier tracking loop initialization signal, a frequency-locked loop is used to quickly track the Doppler residual after carrier acquisition, and a carrier signal containing Doppler residual information is output. S3: Estimate the Doppler rate of change of the carrier signal using a Kalman filter; S4: Based on the carrier signal, a carrier phase-locked loop is used to dynamically adjust the loop gain based on the Doppler rate of change, update the carrier tracking loop parameters, dynamically compensate for Doppler changes, and output a high-precision carrier tracking signal; S5: Obtain the weighting coefficients of the matched filter based on the roll-off factor and symbol rate of the baseband I / Q signal; weight the high-precision carrier tracking signal to obtain the optimized signal; S6: Perform multi-channel processing on the optimized signal and output the coarse estimation results for each channel, including the coarse estimate of the carrier frequency, the change in signal-to-noise ratio for each channel, and the variance of phase noise for each channel. S7: Based on the coarse estimation results of each channel, select the optimal channel and compress the carrier offset range of the optimal channel; S8: Based on the carrier deviation range of the optimal channel, compensate for the phase of the high-precision carrier tracking signal and output the high-precision demodulation result of the deep space high dynamic low code rate signal.
7. The demodulation and tracking processing method according to claim 6, characterized in that, Step S6 specifically includes: 1) Channel partitioning: Divide the optimized signal into equal channels. Parallel access roads; 2) Spectrum detection: using The sampling rate and high-frequency clock are used to perform spectrum analysis on each signal to detect the location of the maximum spectral peak. 3) Sampling point optimization: based on phase noise variance Determine whether to dynamically add or remove sampling points; 4) Jump point suppression: Weighted processing of the first / last sampling points of the symbol during mid-phase / in-phase integration; 5) Channel output: Coarse estimate of carrier frequency for each channel. and demodulation performance indicators ,in For the first Changes in the signal-to-noise ratio of the road channel.
8. The demodulation and tracking processing method according to claim 6, characterized in that, In step S4, the method for dynamically adjusting the loop gain based on the Doppler rate of change is as follows: In the formula, For the initial , The set capture range The maximum value.
9. The demodulation and tracking processing method according to claim 6, characterized in that, In step S2, the acquisition range for carrier acquisition is: .
10. The demodulation and tracking processing method according to claim 9, characterized in that, In step S7, based on the coarse estimation results of each channel, channels whose signal-to-noise ratio change exceeds a set change threshold and whose phase noise variance is lower than a set variance threshold are selected, and the carrier offset range of the channels is compressed to... .