Satellite signal adaptive acquisition method based on through-fusion system

Abstract

The application relates to a satellite signal adaptive acquisition method based on a through-transmission fusion system. The method comprises the following steps: setting an initial switching threshold and a step value; taking a current switching threshold as a judgment threshold, and statistically assisting the acquisition of an effective receiving frame number and a hardware resource consumption proportion of a satellite transit overall signal-to-noise ratio change rule based mode and a direct acquisition mode; calculating an overall receiving success rate and a total hardware resource consumption proportion, and calculating an overall score value by using a weight coefficient; selecting a switching threshold with the highest overall score value as the best switching threshold through iterative optimization; and comparing a real-time signal-to-noise ratio with the best switching threshold to select an acquisition mode to complete signal acquisition when a satellite actually transits. The method can ensure a receiving success rate while optimizing hardware resource consumption, and realizes a compromise between a high acquisition success rate and low complexity hardware.

Description

Technical Field

[0001] This application relates to the field of integrated satellite communication and navigation technology, and in particular to an adaptive satellite signal acquisition method based on a communication and navigation fusion system. Background Technology

[0002] The current trend in satellite constellation design is towards integrated communication and navigation, with increasingly close collaboration between communication and navigation services. At the same time, considering the increasingly congested navigation spectrum resources, specific frequency bands of navigation resources will be allocated within the communication frequency bands.

[0003] Traditional two-dimensional time-frequency acquisition methods for low-Earth orbit (LEO) satellite communication signals are complex and require high signal-to-noise ratios (SNRs), making them unsuitable for reliable real-time processing. The PMF-FFT acquisition method used in navigation requires a spreading code sequence with a sufficiently long integration time, making it unsuitable for direct application to non-spread spectrum communication signals.

[0004] Existing acquisition schemes fail to fully utilize the characteristics of the convergence of communication and navigation services, making it difficult to simultaneously achieve a high acquisition success rate under low signal-to-noise ratio conditions and low hardware complexity. They are also unsuitable for application scenarios where the signal-to-noise ratio changes dynamically throughout the entire transit of low-orbit satellites. Summary of the Invention

[0005] Therefore, it is necessary to provide a satellite signal adaptive acquisition method based on communication and navigation fusion, which can improve the acquisition success rate under low signal-to-noise ratio conditions while balancing the complexity of hardware implementation, in order to address the above-mentioned technical problems.

[0006] An adaptive satellite signal acquisition method based on a communication-navigation fusion system is applied to a ground receiver. The ground receiver corresponds to a communication-navigation fusion satellite. The communication and navigation services of the communication-navigation fusion satellite adopt a frequency division multiplexing mechanism and maintain a unified spatiotemporal reference. The spreading code sequence of the navigation service is known to the ground receiver in advance. The method includes: Step 1: Obtain the theoretical signal-to-noise ratio threshold for acquisition corresponding to the unique word sequence of the communication frame; obtain the maximum resource ratio of the receiver hardware corresponding to the auxiliary acquisition mode and the maximum resource ratio of the direct acquisition mode; obtain the system's preset target reception success rate, reception success rate weight coefficient, and resource overhead weight coefficient; set the initial switching threshold and threshold step value. Step 2: Using the switching threshold corresponding to the current iteration as the decision threshold, based on the change law of the received signal-to-noise ratio throughout the satellite's transit, the effective number of received frames and the proportion of hardware resource overhead in the assisted acquisition mode, and the effective number of received frames and the proportion of hardware resource overhead in the direct acquisition mode are statistically analyzed respectively. Step 3: Calculate the overall reception success rate corresponding to the current switching threshold based on the number of effective received frames in the assisted acquisition mode and the direct acquisition mode; obtain the total hardware resource overhead ratio corresponding to the current switching threshold based on the hardware resource overhead ratio of the assisted acquisition mode and the direct acquisition mode. Step 4: Using the reception success rate weight coefficient and the resource overhead weight coefficient, combined with the current overall reception success rate and the proportion of total hardware resource overhead, calculate the overall score value corresponding to the current handover threshold. Step 5: Determine whether the current iteration result meets the preset iteration termination condition. If not, update the switching threshold according to the threshold step value and return to step 2. If it meets the condition, summarize the switching thresholds obtained from all iterations and their corresponding overall score values, and select the switching threshold with the highest overall score value as the optimal switching threshold. Step 6: During the actual satellite transit, the signal-to-noise ratio of the received signal is estimated in real time, and the real-time signal-to-noise ratio is compared with the optimal switching threshold. Based on the comparison result, the corresponding acquisition mode is selected to complete the satellite signal acquisition.

[0007] The aforementioned adaptive satellite signal acquisition method based on a communication-navigation fusion system utilizes the characteristics of frequency division multiplexing of communication and navigation services, unified spatiotemporal reference, and known navigation spreading code sequence under the communication-navigation fusion system to construct a dual-mode acquisition architecture combining navigation spreading code-assisted acquisition and direct acquisition using unique communication words. Simultaneously, a step-iterative threshold optimization method is employed, using a weighted comprehensive score of reception success rate and hardware resource overhead to solve for the optimal switching threshold. Finally, during the actual satellite transit, the acquisition mode is adaptively switched based on the comparison between the real-time signal-to-noise ratio and the optimal threshold, ensuring a high reception success rate. Correspondingly, This technology can, on the one hand, compensate for the deterioration of signal-to-noise ratio (SNR) in low SNR scenarios by leveraging the correlation gain of navigation spreading codes, breaking through the SNR threshold limitation of traditional unique word direct acquisition and solving the problem of insufficient acquisition success rate under low elevation angle and low SNR conditions. On the other hand, it can use short unique words for direct acquisition in high SNR scenarios to control hardware resource consumption. At the same time, it achieves a precise trade-off between acquisition performance and hardware complexity by using the optimal switching threshold through quantization optimization. This solves the technical problems of traditional acquisition schemes being unable to simultaneously take into account low SNR acquisition capabilities and low hardware implementation costs, and being difficult to adapt to the dynamic changes in SNR throughout the satellite's transit. Attached Figure Description

[0008] Figure 1 This is a flowchart illustrating a satellite signal adaptive acquisition method based on a communication-navigation fusion system in one embodiment. Figure 2 This is a schematic diagram of the mode switching process in one embodiment. Detailed Implementation

[0009] To make the objectives, technical solutions, 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.

[0010] In one embodiment, such as Figure 1 As shown, an adaptive satellite signal acquisition method based on a communication-navigation fusion system is provided, applied to a ground receiver. The ground receiver corresponds to a communication-navigation fusion satellite. The communication and navigation services of the communication-navigation fusion satellite adopt a frequency division multiplexing mechanism and maintain a unified spatiotemporal reference. The spreading code sequence of the navigation service is known to the ground receiver in advance. The method includes the following steps: Step 1: Obtain the theoretical signal-to-noise ratio threshold for acquisition corresponding to the unique word sequence of the communication frame; obtain the maximum resource ratio of the receiver hardware corresponding to the auxiliary acquisition mode and the maximum resource ratio of the direct acquisition mode; obtain the system's preset target reception success rate, reception success rate weight coefficient, and resource overhead weight coefficient; set the initial switching threshold and threshold step value.

[0011] Given the acquisition probability and false alarm probability, the theoretical signal-to-noise ratio threshold Ta required for acquiring the unique word sequence of the communication frame can be obtained through Monte Carlo simulation. The auxiliary acquisition mode uses a long spreading code sequence, resulting in higher hardware logic resource overhead; the direct acquisition mode uses a short code, resulting in lower overhead. The maximum hardware resource usage available for the auxiliary acquisition mode is denoted as Res1, and the maximum available for the direct acquisition mode is denoted as Res2. The expected reception success rate is denoted as S. Weighting coefficients are also included. Weights are allocated to target reception success rate and target resource overhead based on actual system requirements. An initial acquisition threshold is preset. Each step By obtaining and setting the above parameters, initial conditions and constraint boundaries are provided for subsequent iterative optimization.

[0012] Step 2: Using the switching threshold corresponding to the current iteration as the decision threshold, based on the change pattern of the received signal-to-noise ratio throughout the satellite's transit, the effective number of received frames and the proportion of hardware resource overhead in the assisted acquisition mode, and the effective number of received frames and the proportion of hardware resource overhead in the direct acquisition mode are statistically analyzed respectively.

[0013] The number of communication frames broadcast by the satellite from entry to exit. N， Actual number of frames received M The success rate of receiving the message is M / N By judging the SNR and the λth step... The capture mode is switched based on the relationship between the two. The number of frames received in assisted capture mode is counted after each step. Capture hardware resource overhead (%), Number of frames received in direct capture mode Capture hardware resource overhead (%) Resource Expenditure The percentage represents the hardware logic resources used during the corresponding capture mode. By using the current switching threshold as the decision threshold and performing statistical analysis based on the signal-to-noise ratio variation pattern, the correspondence between the statistical data and the current threshold is ensured.

[0014] Step 3: Calculate the overall reception success rate corresponding to the current switching threshold based on the number of valid received frames in assisted acquisition mode and direct acquisition mode; obtain the total hardware resource overhead ratio corresponding to the current switching threshold based on the hardware resource overhead ratio of assisted acquisition mode and direct acquisition mode.

[0015] By calculating the overall reception success rate and the proportion of total hardware resource consumption, two quantitative indicators are provided for the subsequent comprehensive scoring.

[0016] Step 4: Using the reception success rate weight coefficient and the resource overhead weight coefficient, combined with the current overall reception success rate and the proportion of total hardware resource overhead, calculate the overall score value corresponding to the current handover threshold.

[0017] By updating the switching threshold step value one by one and repeatedly calculating the statistics, different switching threshold schemes can be traversed. When the iteration result meets the preset termination condition, the iteration stops, and the switching threshold with the highest overall score is selected from all effective schemes as the optimal switching threshold, thereby achieving the optimal trade-off between reception performance and hardware overhead.

[0018] Step 5: Determine whether the current iteration result meets the preset iteration termination condition. If not, update the switching threshold according to the threshold step value and return to step 2. If it meets the condition, summarize the switching thresholds obtained from all iterations and their corresponding overall score values, and select the switching threshold with the highest overall score value as the optimal switching threshold.

[0019] The iteration ends when the reception success rate reaches S or the resource overhead of a certain mode reaches its maximum. Specifically, the iteration ends when the overall reception success rate reaches the preset target reception success rate S, or when the hardware resource overhead of the auxiliary acquisition mode reaches its maximum. Res1, which corresponds to its maximum resource allocation, or the hardware resource overhead of the direct capture mode. The iteration terminates when the corresponding maximum resource percentage Res2 is reached. If the above termination condition is not met, a threshold step value is added to the switching threshold used in the current iteration. This yields the switching threshold for the next iteration. The highest score among these thresholds is then used to determine the optimal threshold. The optimal switching threshold is determined by calculating the overall score through multiple rounds of iterative steps. For example... Figure 2As shown, the mode switching process specifically presents the logic of the above-mentioned iterative optimization and threshold decision.

[0020] Step 6: During the actual satellite transit, estimate the signal-to-noise ratio (SNR) of the received signal in real time, compare the real-time SNR with the optimal switching threshold, and select the corresponding acquisition mode based on the comparison result to complete satellite signal acquisition.

[0021] During the actual satellite transit signal reception process, the optimal switching threshold obtained through offline optimization is used as the decision criterion. The corresponding acquisition mode is dynamically selected based on the real-time estimated received signal-to-noise ratio, which can adapt to the dynamic changes in signal-to-noise ratio throughout the entire satellite transit process, ensuring reception success rate while controlling hardware overhead.

[0022] In the above method, the theoretical signal-to-noise ratio (SNR) threshold for acquisition based on the unique word sequence of the communication frame and the receiver hardware resource constraints are obtained. An initial switching threshold and step value are set, and the current switching threshold is used as the decision threshold. Based on the SNR change pattern throughout the satellite transit, the number of effective received frames and the proportion of hardware resource overhead in the assisted acquisition mode and the direct acquisition mode are statistically analyzed. Then, the overall reception success rate and the total hardware resource overhead proportion are calculated. Using a weighted coefficient for comprehensive scoring, the switching threshold with the highest score is selected as the optimal switching threshold through step iteration. Finally, in actual transit, the acquisition mode is selected by comparing the real-time SNR with the optimal switching threshold. This combines the reception success rate and hardware resource overhead, which were originally separate factors. The optimization objectives are uniformly incorporated into the iterative optimization framework, so that the determination of the switching threshold no longer depends on a single signal-to-noise ratio threshold or empirical value. Instead, under the system's preset resource constraints and success rate requirements, it adaptively approaches the global optimal solution through multiple rounds of step-by-step iterations. This avoids the problem of traditional schemes failing to capture at low elevation angles due to falling below the unique word capture threshold, and also avoids the resource waste caused by blindly using high-overhead auxiliary capture modes at high elevation angles. At the same time, the preset iteration termination condition achieves rapid convergence under engineering constraints. Thus, while ensuring that the overall reception success rate meets the expected requirements, it minimizes hardware logic resource overhead and achieves an effective trade-off between high capture success rate and low hardware complexity. In one embodiment, the overall reception success rate corresponding to the current switching threshold is calculated based on the number of effective received frames in the assisted acquisition mode and the direct acquisition mode, including: Based on the number of effective received frames in assisted acquisition mode and direct acquisition mode, calculate the overall reception success rate corresponding to the current switching threshold. ,in, To determine the effective number of received frames in assisted capture mode, This represents the number of valid received frames in direct capture mode. The total number of communication frames broadcast throughout the satellite's transit.

[0023] Specifically, from the time the satellite enters the country to the time it leaves the country, it broadcasts N communication frames, and the actual number of frames received is... The success rate of receiving the message is The reception success rate reflects the overall acquisition performance of the receiver under the current handover threshold and is an important indicator for measuring whether the handover threshold is reasonable.

[0024] In one embodiment, the total hardware resource overhead ratio corresponding to the current switching threshold is obtained based on the hardware resource overhead ratio between the assisted capture mode and the direct capture mode, including: Based on the hardware resource overhead ratios of the assisted capture mode and the direct capture mode, the total hardware resource overhead ratio corresponding to the current switching threshold is obtained as follows: ,in, To reduce the hardware resource overhead in the auxiliary capture mode, This represents the percentage of hardware resource overhead in direct capture mode.

[0025] Specifically, the auxiliary acquisition mode uses a long spreading code sequence, which has a higher hardware logic resource overhead, while the direct acquisition mode uses a short code, which has a lower overhead. and The hardware resource usage in the two modes is expressed as a percentage, representing the percentage of total hardware resource overhead. This reflects the overall resource consumption level under the current switching threshold.

[0026] In one embodiment, the overall score corresponding to the current handover threshold is calculated by using the reception success rate weight coefficient and the resource overhead weight coefficient, combined with the current overall reception success rate and the proportion of total hardware resource overhead. This includes: Using the reception success rate weighting coefficient and resource overhead weighting coefficient, combined with the current overall reception success rate and the proportion of total hardware resource overhead, the overall score value corresponding to the current handover threshold is calculated as follows:

[0027] in, This is the overall score. This is a weighting coefficient for the success rate of receiving data. This is the resource cost weighting coefficient. To determine the effective number of received frames in assisted capture mode, This represents the number of valid received frames in direct capture mode. This refers to the total number of communication frames broadcast throughout the satellite's transit. To reduce the hardware resource overhead in the auxiliary capture mode, This represents the percentage of hardware resource overhead in direct capture mode.

[0028] Specifically, the reception success rate and hardware resource overhead are weighted and fused using corresponding weighting coefficients to obtain an overall score value that can be compared horizontally. By adjusting the values ​​of the two weighting coefficients, the emphasis on reception performance and hardware overhead in the evaluation can be changed to adapt to different system implementation requirements.

[0029] In one embodiment, the iteration termination condition is that the overall reception success rate corresponding to the current iteration reaches the preset target reception success rate, or the hardware resource overhead ratio of the assisted acquisition mode reaches its corresponding maximum resource ratio, or the hardware resource overhead ratio of the direct acquisition mode reaches its corresponding maximum resource ratio.

[0030] Specifically, the iteration terminates when the reception success rate reaches S or the resource overhead of a certain mode reaches its maximum. The maximum hardware resource overhead available for the assisted acquisition mode is Res1, and the maximum available for the direct acquisition mode is Res2. This termination condition reflects the constraint priority principle in engineering practice, avoiding invalid iterations.

[0031] In one embodiment, when the real-time signal-to-noise ratio is less than or equal to the optimal switching threshold in step 6, the auxiliary acquisition mode is selected, including: using the spreading code sequence of the navigation band to complete signal acquisition, obtaining the frame time slot start position and coarse frequency offset estimate, and using the frame time slot start position and coarse frequency offset estimate as auxiliary information to directly perform fine frequency offset estimation and data segment demodulation and decoding processing on the communication service receiving link.

[0032] Specifically, in the low elevation angle segment, the signal-to-noise ratio (SNR) deteriorates sharply, falling below the SNR threshold for unique word sequence acquisition, making direct acquisition impossible. Acquisition can be achieved using the navigation segment spreading code sequence; the acquisition process is existing technology and will not be elaborated upon in this application. The deterioration of the SNR is compensated by the spreading correlation gain, obtaining the frame slot start position and coarse frequency offset estimate (which can be directly obtained using the PMF-FFT method in existing navigation signal processing technology). This information is provided as auxiliary information to the communication service reception process, allowing the communication frame to skip the acquisition process and directly perform fine frequency offset estimation and data segment demodulation and decoding. This mode is suitable for scenarios with low elevation angles and rapidly deteriorating SNR, where the SNR is below the SNR threshold for unique word sequence acquisition, making direct acquisition impossible via the communication frame. The spreading correlation gain of the navigation segment spreading code sequence can compensate for the SNR deterioration, completing signal acquisition and obtaining the frame slot start position and coarse frequency offset estimate. Providing this information as auxiliary information to the communication service reception process allows the communication frame to skip the acquisition process and directly perform fine frequency offset estimation and data segment demodulation and decoding.

[0033] In one embodiment, when the real-time signal-to-noise ratio is greater than the optimal switching threshold, the direct acquisition mode is selected, including: using the first unique word of the communication frame to complete the initial acquisition, and then using the second unique word of the communication frame to complete the secondary acquisition verification. After the verification is passed, frequency offset fine estimation and data segment demodulation and decoding processing are performed.

[0034] Specifically, in the high elevation angle segment, where the signal-to-noise ratio (SNR) is good, a unique word UW1 sequence is used for initial acquisition, followed by a second acquisition using the UW2 sequence, and then fine frequency offset estimation and data segment demodulation and decoding are performed. This two-stage acquisition verification improves the reliability of the direct acquisition mode. This mode is suitable for scenarios with high elevation angles and good SNR, where the SNR meets the threshold requirements for unique word acquisition. Initial acquisition using the first unique word, followed by a second unique word for verification, enhances acquisition reliability. Once verification is successful, fine frequency offset estimation and data segment demodulation and decoding can be performed. This mode also has lower hardware resource overhead.

[0035] In one embodiment, the communication service of the communication and navigation fusion satellite adopts a burst frame structure. The burst frame is composed of a frame start guard interval, a first unique word, a first segment, a second unique word, a second segment, and a frame end guard interval in sequence, and adopts MPSK modulation, wherein the unique word is a non-spread spectrum sequence.

[0036] Specifically, this burst frame structure is the data transmission frame structure used in satellite communication services. The guard intervals at the beginning and end of the frame are used to cope with the delay fluctuations in signal transmission; the unique word is used for frame synchronization acquisition, and it is a non-spread spectrum sequence with a short code length; the message segment is used to carry service data and uses MPSK modulation to complete the data transmission.

[0037] In one embodiment, updating the switching threshold according to the threshold step value includes: adding a threshold step value to the switching threshold used in the current iteration to obtain the switching threshold used in the next iteration.

[0038] Specifically, updating and switching thresholds by progressively adding fixed step values ​​allows for ordered traversal of threshold values, ensuring the controllability and feasibility of the iteration process. Traversing the search interval in a step-by-step manner ensures that no possible optimal threshold value is overlooked.

[0039] In one embodiment, by adjusting the ratio of the reception success rate weight coefficient to the resource overhead weight coefficient, multiple sets of optimal handover thresholds are obtained that are biased towards high reception success rate and low hardware resource overhead, respectively.

[0040] Specifically, when the system prioritizes reception performance, the value of the reception success rate weight coefficient can be increased to obtain the optimal switching threshold biased towards high reception success rate; when the system prioritizes hardware cost control, the value of the resource overhead weight coefficient can be increased to obtain the optimal switching threshold biased towards low hardware resource overhead, thereby flexibly adapting to different receiver requirements.

[0041] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A satellite signal adaptive acquisition method based on a communication-navigation fusion system, applied to a ground receiver, wherein the ground receiver corresponds to a communication-navigation fusion satellite, the communication and navigation services of the communication-navigation fusion satellite adopt a frequency division multiplexing mechanism and maintain a unified spatiotemporal reference, and the spreading code sequence of the navigation service is known in advance by the ground receiver, characterized in that, The method includes: Step 1: Obtain the theoretical signal-to-noise ratio threshold for acquisition corresponding to the unique word sequence of the communication frame; obtain the maximum resource ratio of the receiver hardware corresponding to the auxiliary acquisition mode and the maximum resource ratio of the direct acquisition mode; obtain the system's preset target reception success rate, reception success rate weight coefficient, and resource overhead weight coefficient; set the initial switching threshold and threshold step value. Step 2: Using the switching threshold corresponding to the current iteration as the decision threshold, based on the change law of the received signal-to-noise ratio throughout the satellite's transit, the effective number of received frames and the proportion of hardware resource overhead in the assisted acquisition mode, and the effective number of received frames and the proportion of hardware resource overhead in the direct acquisition mode are statistically analyzed respectively. Step 3: Calculate the overall reception success rate corresponding to the current switching threshold based on the number of effective received frames in the assisted acquisition mode and the direct acquisition mode; obtain the total hardware resource overhead ratio corresponding to the current switching threshold based on the hardware resource overhead ratio of the assisted acquisition mode and the direct acquisition mode. Step 4: Using the reception success rate weight coefficient and resource overhead weight coefficient, combined with the current overall reception success rate and the proportion of total hardware resource overhead, calculate the overall score value corresponding to the current handover threshold. Step 5: Determine whether the current iteration result meets the preset iteration termination condition. If not, update the switching threshold according to the threshold step value and return to step 2. If it meets the condition, summarize the switching thresholds obtained from all iterations and their corresponding overall score values, and select the switching threshold with the highest overall score value as the optimal switching threshold. Step 6: During the actual satellite transit, the signal-to-noise ratio of the received signal is estimated in real time, and the real-time signal-to-noise ratio is compared with the optimal switching threshold. Based on the comparison result, the corresponding acquisition mode is selected to complete the satellite signal acquisition.

2. The method according to claim 1, characterized in that, Based on the number of valid received frames in assisted acquisition mode and direct acquisition mode, calculate the overall reception success rate corresponding to the current switching threshold, including: Based on the number of effective received frames in assisted acquisition mode and direct acquisition mode, calculate the overall reception success rate corresponding to the current switching threshold. ,in, To determine the effective number of frames received in assisted capture mode, This represents the number of valid received frames in direct capture mode. The total number of communication frames broadcast throughout the satellite's transit.

3. The method according to claim 1, characterized in that, Based on the hardware resource overhead ratios of the assisted capture mode and the direct capture mode, the total hardware resource overhead ratio corresponding to the current switching threshold is obtained, including: Based on the hardware resource overhead ratios of the assisted capture mode and the direct capture mode, the total hardware resource overhead ratio corresponding to the current switching threshold is obtained as follows: ,in, To reduce the hardware resource overhead in the auxiliary capture mode, This represents the percentage of hardware resource overhead in direct capture mode.

4. The method according to claim 1, characterized in that, Using the aforementioned reception success rate weighting coefficient and resource overhead weighting coefficient, combined with the current overall reception success rate and the proportion of total hardware resource overhead, the overall score value corresponding to the current handover threshold is calculated, including: Using the aforementioned reception success rate weighting coefficient and resource overhead weighting coefficient, combined with the current overall reception success rate and the proportion of total hardware resource overhead, the overall score value corresponding to the current handover threshold is calculated as follows: in, This is the overall score. This is a weighting coefficient for the success rate of receiving data. This is the resource cost weighting coefficient. To determine the effective number of received frames in assisted capture mode, This represents the number of valid received frames in direct capture mode. This refers to the total number of communication frames broadcast throughout the satellite's transit. To reduce the hardware resource overhead in the auxiliary capture mode, This represents the percentage of hardware resource overhead in direct capture mode.

5. The method according to claim 1, characterized in that, The iteration termination condition is that the overall reception success rate of the current iteration reaches the preset target reception success rate, or the hardware resource overhead ratio of the auxiliary acquisition mode reaches its corresponding maximum resource ratio, or the hardware resource overhead ratio of the direct acquisition mode reaches its corresponding maximum resource ratio.

6. The method according to claim 1, characterized in that, In step 6, when the real-time signal-to-noise ratio is less than or equal to the optimal switching threshold, the auxiliary acquisition mode is selected, including: using the spreading code sequence of the navigation frequency band to complete signal acquisition, obtaining the frame time slot start position and coarse frequency offset estimate, and using the frame time slot start position and coarse frequency offset estimate as auxiliary information input to the communication service receiving link to directly perform fine frequency offset estimation and data segment demodulation and decoding processing.

7. The method according to claim 1, characterized in that, When the real-time signal-to-noise ratio is greater than the optimal switching threshold, the direct acquisition mode is selected, including: using the first unique word of the communication frame to complete the initial acquisition, and then using the second unique word of the communication frame to complete the secondary acquisition verification. After the verification is passed, the frequency offset is precisely estimated and the data segment demodulation and decoding process is performed.

8. The method according to claim 1, characterized in that, The communication service of the communication and navigation fusion satellite adopts a burst frame structure. The burst frame is composed of a frame start guard interval, a first unique word, a first segment, a second unique word, a second segment, and a frame end guard interval in sequence. It adopts MPSK modulation, where the unique word is a non-spread spectrum sequence.

9. The method according to claim 1, characterized in that, The step of updating the switching threshold according to the threshold step value includes: adding the threshold step value once to the switching threshold used in the current iteration to obtain the switching threshold used in the next iteration.

10. The method according to claim 1, characterized in that, The method further includes: By adjusting the ratio of the reception success rate weight coefficient to the resource overhead weight coefficient, multiple sets of optimal handover thresholds are obtained, which respectively favor high reception success rate and low hardware resource overhead.

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