Satellite signal symbol level processing method and electronic device

Abstract

The application provides a satellite signal symbol level processing method and an electronic device. The baseband oversampling data is first subjected to a matched filtering process, and a local synchronization header sequence is subjected to an oversampling process to obtain a local oversampling synchronization header sequence. The local oversampling synchronization header sequence is subjected to a pairwise conjugate process to obtain a local synchronization header differential sequence, and then is subjected to a differential correlation with a baseband oversampling differential sequence obtained by subjecting the baseband oversampling data to a pairwise conjugate process, to obtain a cross-correlation sequence. Thus, the baseband oversampling synchronization header differential sequence is extracted, and a compensation frequency offset value is calculated based on a phase deviation between the local synchronization header differential sequence, to perform frequency offset compensation. Each frame of data after the frequency offset compensation is subjected to symbol synchronization processing and carrier recovery processing in parallel, thereby improving the satellite signal processing efficiency, effectively resisting the influence of a large frequency offset, and solving the problem of the estimation accuracy decline of blind frequency offset estimation in a low signal-to-noise ratio or high-order modulation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite signal processing, in particular to a satellite signal symbol level processing method and an electronic device. BACKGROUND

[0002] The current mainstream satellite signal (such as DVBS2) symbol level processing flow is as shown in the figure Figure 1 , first, the oversampled baseband data is converted into symbol data after matching filtering and symbol synchronization, then the symbol data and the local synchronization header sequence are cross-correlated, the frame synchronization is completed by searching for a correlation peak greater than a threshold; then the single synchronization header in the received signal or the phase difference between multiple synchronization headers is used for coarse frequency offset estimation and compensation, and finally the carrier recovery is performed by using a phase-locked loop to complete the symbol level processing.

[0003] However, the oversampled baseband data is continuously subjected to symbol synchronization, especially when using a synchronization method with a feedback loop, the processing efficiency is reduced, and the real-time performance of signal processing is affected; in addition, when the Doppler frequency offset is large (the normalized frequency offset is greater than 0.006), the signal after matching filtering and symbol synchronization may not be able to find a correlation peak greater than a threshold by using the cross-correlation method, and the accuracy of frame synchronization is reduced; similarly, in the case where the synchronization header cannot be found, the frequency offset estimation method with auxiliary information cannot be used, and other blind estimation methods such as FFT frequency offset estimation must be used, and the estimation accuracy of the method sharply decreases in low signal-to-noise ratio or high-order modulation. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a satellite signal symbol level processing method and an electronic device, which can improve the satellite signal processing efficiency, effectively resist the influence of large frequency offset, and solve the problem of decreased estimation accuracy of blind frequency offset estimation in low signal-to-noise ratio or high-order modulation.

[0005] The satellite signal symbol level processing method provided by the embodiment of the present application comprises:

[0006] The first baseband oversampled data is subjected to matching filtering processing by using a filter consistent with the sending end, and the second baseband oversampled data is obtained;

[0007] The local synchronization header sequence agreed by the sending and receiving ends is subjected to oversampling processing, and the local oversampled synchronization header sequence with the same oversampling multiple as the first baseband oversampled data is obtained;

[0008] The local oversampled synchronization header sequence is subjected to pairwise conjugate processing to obtain a local synchronization header differential sequence, and then the baseband oversampled differential sequence obtained by performing pairwise conjugate processing on the second baseband oversampled data is subjected to differential correlation, and a cross-correlation sequence is obtained;

[0009] taking out a baseband oversampling synchronization head differential sequence in the baseband oversampling differential sequence based on the cross-correlation sequence, and calculating a phase deviation between the baseband oversampling synchronization head differential sequence and the local synchronization head differential sequence to determine a compensation frequency deviation value;

[0010] compensating for a frequency deviation of the second baseband oversampling data based on the compensation frequency deviation value to obtain third baseband oversampling data;

[0011] performing symbol synchronization processing and carrier recovery processing on each frame of data in the third baseband oversampling data in parallel to obtain single-sampling symbol data.

[0012] In some embodiments, in the satellite signal symbol-level processing method, the local synchronization head sequence agreed by the transmitting and receiving ends is oversampled to obtain a local oversampling synchronization head sequence having the same oversampling multiple as the first baseband oversampling data, including:

[0013] performing shaping filter processing on the local synchronization head sequence agreed by the transmitting and receiving ends based on a roll-off coefficient, an impulse length, and an oversampling multiple of the transmitting end to obtain the local oversampling synchronization head sequence; the local oversampling synchronization head sequence has the same oversampling multiple as the first baseband oversampling data.

[0014] In some embodiments, in the satellite signal symbol-level processing method, the local oversampling synchronization head sequence is processed in pairs to obtain a local synchronization head differential sequence, and the local synchronization head differential sequence is correlated with a baseband oversampling differential sequence obtained by processing the second baseband oversampling data in pairs to obtain a cross-correlation sequence, including:

[0015] performing conjugate multiplication on adjacent two sample points in the local oversampling synchronization head sequence to obtain the local synchronization head differential sequence;

[0016] buffering a buffer data sequence having the same length as the local oversampling synchronization head sequence from the second baseband oversampling data;

[0017] performing conjugate multiplication on adjacent two sample points in the buffer data sequence to obtain a buffer data differential sequence;

[0018] performing cross-correlation operation on the local synchronization head differential sequence and the buffer data differential sequence to obtain the cross-correlation sequence.

[0019] In some embodiments, in the satellite signal symbol-level processing method, the baseband oversampling synchronization head differential sequence in the baseband oversampling differential sequence is taken out based on the cross-correlation sequence, including:

[0020] performing modulo operation on the cross-correlation sequence, and performing correlation peak search on the cross-correlation sequence after the modulo operation based on a preset threshold;

[0021] If no correlation peak is searched, updating the cache data sequence; the updating of the cache data sequence is based on the second baseband oversampling data sliding back by one sample point as a whole;

[0022] If a correlation peak is searched, recording the index position of the peak value of the correlation peak, and based on the index position, taking out the baseband oversampling sync head difference sequence in the baseband oversampling difference sequence.

[0023] In some embodiments, in the satellite signal symbol level processing method, the calculation of the phase deviation between the baseband oversampling sync head difference sequence and the local sync head difference sequence to determine the compensation frequency offset value comprises:

[0024] Conjugate multiplication of the baseband oversampling sync head difference sequence and the local sync head difference sequence to determine a phase difference sequence; the phase difference sequence includes the phase difference corresponding to each sample point in the baseband oversampling sync head difference sequence;

[0025] The phase difference in the phase difference sequence is processed by mean value to obtain a frequency offset value corresponding to a single correlation peak;

[0026] When a plurality of correlation peaks are searched continuously and the index positions of the peak values of the plurality of correlation peaks meet the preset locking state condition, it is determined that the locking state is met, and the mean value of the frequency offset values corresponding to the plurality of correlation peaks is taken as the compensation frequency offset value.

[0027] In some embodiments, in the satellite signal symbol level processing method, the index positions of the peak values of the plurality of correlation peaks meet the preset locking state condition, which is:

[0028] The difference value between any two of the index positions of the peak values of the plurality of correlation peaks is equal to the frame length of the second baseband oversampling data multiplied by sps.

[0029] In some embodiments, in the satellite signal symbol level processing method, the plurality of correlation peaks is three.

[0030] In some embodiments, in the satellite signal symbol level processing method, the frequency offset compensation of the second baseband oversampling data based on the frequency offset value to obtain third baseband oversampling data comprises:

[0031] The frequency offset compensation of the second baseband oversampling data based on the following formula:

[0032]

[0033] Wherein, The second baseband oversampling data is represented by The third baseband oversampling data obtained after frequency offset compensation is represented by; the characterize the compensation frequency offset value; the characterize the parameter for ensuring the continuity of the phase, the initial value is 0, .

[0034] In some embodiments, the satellite signal symbol level processing method, the symbol synchronization processing and the carrier recovery processing are performed in parallel on each frame of data in the third baseband oversampling data, and single-sampling symbol data is obtained, comprising:

[0035] The third baseband oversampling data is divided into multiple data frames based on the frame synchronization index result, and the frame synchronization index result includes the index position of the peak value of the correlation peak;

[0036] A plurality of CPU cores are called to perform symbol synchronization processing and carrier recovery processing in parallel on the plurality of data frames of the third baseband oversampling data, and single-sampling symbol data is obtained.

[0037] In some embodiments, an electronic device is also provided, comprising a processor, a memory and a bus, the memory stores machine readable instructions executable by the processor, when the electronic device is running, the processor and the memory communicate through the bus, and the machine readable instructions are executed by the processor to perform the steps of the satellite signal symbol level processing method.

[0038] In the embodiments of the present application, a satellite signal symbol level processing method and an electronic device are provided. Based on the characteristics that each frame of a satellite signal is independent of each other, the method performs frame processing in advance after matched filtering, and different CPU cores can be called to perform symbol synchronization and subsequent carrier recovery processing of each frame simultaneously in parallel processing mode, thereby improving processing efficiency and increasing the symbol rate that can be processed in the same time. In addition, for the influence of the large frequency offset on frame synchronization, the synchronization header sequence is up-sampled and conjugated, and then differentially correlated with the oversampled baseband signal after conjugation, so that the synchronization header position can be accurately found, the influence of large frequency offset can be effectively resisted, the accuracy of frame synchronization can be improved, and the estimation accuracy of blind frequency offset estimation in low signal-to-noise ratio or high-order modulation can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0040] Figure 1A flow chart showing a conventional DVBS2 symbol level processing flow;

[0041] Figure 2 A flow chart showing a satellite signal symbol level processing method according to an embodiment of the present application;

[0042] Figure 3 Another flow chart showing a satellite signal symbol level processing method according to an embodiment of the present application;

[0043] Figure 4 A direct correlation result of oversampled baseband data is shown;

[0044] Figure 5 A result of differential correlation method according to an embodiment of the present application is shown;

[0045] Figure 6 A direct correlation result of oversampled baseband signal after frequency offset compensation by frequency offset estimation method according to an embodiment of the present application is shown;

[0046] Figure 7 A structural schematic diagram of an electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application are only intended to illustrate and describe the present application, and are not intended to limit the protection scope of the present application. In addition, it should be understood that the schematic drawings are not drawn according to the actual proportions. The flow charts in the present application show the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flow charts can not be implemented in sequence, and the steps without logical context relationship can be reversed in sequence or implemented simultaneously. In addition, one or more other operations can be added to the flow charts or removed from the flow charts by those skilled in the art under the guidance of the content of the present application.

[0048] In addition, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0049] It should be noted that the term "comprising" will be used in the embodiments of the present application to specify the presence of stated features, but does not exclude the presence of other features.

[0050] The current mainstream satellite signal (such as DVBS2) symbol level processing flow is shown in Figure 1 The over-sampled baseband data is first converted into symbol data through matched filtering and symbol synchronization, and then the symbol data and the local synchronization header sequence are cross-correlated to complete frame synchronization by searching for a correlation peak greater than a threshold; then a single synchronization header in the received signal or the phase difference between multiple synchronization headers is used to perform coarse frequency offset estimation and compensation, and finally a phase-locked loop is used to complete carrier recovery to complete symbol level processing.

[0051] Please refer to Figure 1 , Figure 1 The flowchart of the traditional DVBS2 symbol level processing flow is shown.

[0052] However, the over-sampled baseband data remains continuous for symbol synchronization, especially when using a synchronization method with a feedback loop, which will reduce the processing efficiency and affect the real-time performance of signal processing; in addition, when the Doppler frequency offset is large (the normalized frequency offset is greater than 0.006), the signal after matched filtering and symbol synchronization may not be able to find a correlation peak greater than the threshold through cross-correlation, and the accuracy of frame synchronization decreases; similarly, in the case where the synchronization header cannot be found, the frequency offset estimation method with auxiliary information cannot be used, and other blind estimation methods such as FFT frequency offset estimation must be used, and the estimation accuracy of this method decreases sharply in low SNR or high-order modulation.

[0053] Therefore, in the embodiments of the present application, a satellite signal symbol level processing method and an electronic device are provided, which are based on the feature that each frame of the satellite signal is independent of each other. After matched filtering, the frames are processed in advance, and different CPU cores can be called for symbol synchronization and subsequent carrier recovery processing of each frame in parallel, which improves the processing efficiency and increases the symbol rate that can be processed in the same time. In addition, for the influence of the large frequency offset on frame synchronization, the synchronization header sequence is up-sampled and conjugated, and then the over-sampled baseband signal is differentially correlated, which can accurately find the synchronization header position, effectively resist the influence of large frequency offset, improve the accuracy of frame synchronization, more accurately estimate the frequency offset value, and solve the problem of decrease in estimation accuracy of blind frequency offset estimation in low SNR or high-order modulation.

[0054] Please refer to Figure 2 , Figure 2 The flowchart of the satellite signal symbol level processing method according to the embodiments of the present application is shown; please refer to Figure 3 , Figure 3Another flow chart of the satellite signal symbol level processing method according to the embodiment of the application is shown in FIG. 3. As shown in FIG. 3, the method comprises the following steps. Figure 2 and Figure 3 As shown in FIG. 3, the method comprises the following steps.

[0055] S301, performing matched filtering processing on the first baseband oversampling data by using a filter consistent with the transmitting end to obtain second baseband oversampling data;

[0056] S302, performing oversampling processing on a local synchronization header sequence agreed by the transmitting end and the receiving end to obtain a local oversampling synchronization header sequence with the same oversampling multiple as the first baseband oversampling data;

[0057] S303, performing pairwise conjugate processing on the local oversampling synchronization header sequence to obtain a local synchronization header differential sequence, and performing differential correlation between the baseband oversampling differential sequence obtained by performing pairwise conjugate processing on the second baseband oversampling data to obtain a cross-correlation sequence;

[0058] S304, based on the cross-correlation sequence, taking out a baseband oversampling synchronization header differential sequence in the baseband oversampling differential sequence, and calculating a phase deviation between the baseband oversampling synchronization header differential sequence and the local synchronization header differential sequence to determine a compensation frequency offset value;

[0059] S305, performing frequency offset compensation on the second baseband oversampling data based on the compensation frequency offset value to obtain third baseband oversampling data;

[0060] S306, performing symbol synchronization processing and carrier recovery processing on each frame of data in the third baseband oversampling data in parallel to obtain single-sampling symbol data.

[0061] Please refer to Figure 2 , the traditional satellite signal symbol level processing flow for Figure 1 is optimized as shown in Figure 2 . The part in the dashed box in the figure is the main optimization content, that is, the frame synchronization and frequency offset estimation (i.e. frequency offset compensation method) are modified, and the frame synchronization and frequency offset estimation are jointly processed.

[0062] Here, the frequency offset estimation, i.e. frequency offset coarse estimation and compensation.

[0063] In the step S302, the local synchronization header sequence agreed by the transmitting end and the receiving end is processed by oversampling to obtain a local oversampling synchronization header sequence with the same oversampling multiple as the first baseband oversampling data.

[0064] The local synchronization header sequence agreed by the transmitting end and the receiving end is processed by oversampling to obtain a local oversampling synchronization header sequence with the same oversampling multiple as the first baseband oversampling data, comprising:

[0065] The local oversampling synchronization head sequence is obtained by performing shaping filtering on the local synchronization head sequence agreed by the transceiving end based on the roll-off factor, the impulse length, and the oversampling multiple of the sending end.

[0066] In some embodiments, the local synchronization head sequence agreed by the transceiving end is assumed to be:

[0067] , wherein I The synchronization head contains a number of symbols, and the number of symbols is obtained by performing shaping filtering on the roll-off factor, the impulse length, and the oversampling multiple of the sending end to obtain an oversampling synchronization head sequence as shown in the following formula (1):

[0068] ; ……(1);

[0069] wherein, wherein, The local oversampling synchronization head sequence is obtained by performing shaping filtering on the local synchronization head sequence agreed by the transceiving end based on the roll-off factor, the impulse length, and the oversampling multiple of the sending end. N The local oversampling synchronization head sequence is obtained by performing shaping filtering on the local synchronization head sequence agreed by the transceiving end based on the roll-off factor, the impulse length, and the oversampling multiple of the sending end. N = spsl , sps The number of samples of each symbol is consistent with the oversampling multiple of the received baseband signal.

[0070] In the step S303, the local synchronization head differential sequence is obtained by performing two-by-two conjugate processing on the local oversampling synchronization head sequence, and then the differential correlation is performed between the baseband oversampling differential sequence obtained by performing two-by-two conjugate processing on the second baseband oversampling data, to obtain a cross-correlation sequence.

[0071] The cross-correlation sequence is used to determine the baseband oversampling synchronization head differential sequence in the baseband oversampling differential sequence.

[0072] In some embodiments, the local synchronization head differential sequence is obtained by performing two-by-two conjugate processing on the local oversampling synchronization head sequence, and then the differential correlation is performed between the baseband oversampling differential sequence obtained by performing two-by-two conjugate processing on the second baseband oversampling data, to obtain a cross-correlation sequence, including:

[0073] The local synchronization head differential sequence is obtained by performing conjugate multiplication operation on the adjacent two samples in the local oversampling synchronization head sequence.

[0074] The cache data sequence of the same length is buffered from the second baseband oversampling data according to the length of the local oversampling synchronization head sequence.

[0075] The cache data differential sequence is obtained by performing conjugate multiplication operation on the adjacent two samples in the cache data sequence.

[0076] The local synchronization head difference sequence and the buffer data difference sequence are cross-correlated to obtain a cross-correlation sequence.

[0077] That is, in actual processing, the second baseband oversampling data can be processed in batches, and the buffer data difference sequence is a baseband oversampling difference sequence obtained in single processing.

[0078] In some embodiments, the baseband oversampling data obtained by the formula (1) is The adjacent two samples are conjugate multiplied to obtain a local synchronization head difference sequence, and the formula (2) is as follows:

[0079] ; …… (2) ;

[0080] Wherein represents a conjugate operation, represents a local synchronization head difference sequence.

[0081] According to the length of the oversampling synchronization head sequence N , the second baseband oversampling data

[0082] (G represents the number of samples of the received oversampling baseband data) buffer data

[0083] ( start represents the starting index in r ), and the formula (2) is used to obtain r buf The adjacent two samples are conjugate multiplied to obtain a buffer data difference sequence as shown in the formula (3):

[0084] ; …… (3) ;

[0085] Wherein, represents a buffer data difference sequence.

[0086] The local synchronization head difference sequence obtained by the formula (2) and the buffer data difference sequence (i.e. the baseband oversampling difference sequence in single processing) obtained by the formula (3) are cross-correlated as shown in the formula (4) to obtain a cross-correlation sequence :

[0087] ; …… (4).

[0088] The oversampling synchronization head sequence is differentially operated, and is cross-correlated with the baseband oversampling data after differential operation, which can effectively resist the influence of large frequency offset on correlation.

[0089] In some embodiments, the taking out of the baseband oversampling sync-head differential sequence in the baseband oversampling differential sequence based on the cross-correlation sequence comprises:

[0090] The cross-correlation sequence is taken modulo, and a correlation peak search is performed on the cross-correlation sequence after the taking modulo based on a preset threshold;

[0091] If no correlation peak is searched, an update of the buffered data sequence is performed; the update of the buffered data sequence is based on a backward sliding of the second baseband oversampling data by one sample point;

[0092] If a correlation peak is searched, an index position of a peak value of the correlation peak is recorded, and a baseband oversampling sync-head differential sequence in the baseband oversampling differential sequence is taken out based on the index position.

[0093] In the step S304, a phase deviation between the baseband oversampling sync-head differential sequence and the local sync-head differential sequence is calculated to determine a compensation frequency offset value.

[0094] In some embodiments, the calculation of the phase deviation between the baseband oversampling sync-head differential sequence and the local sync-head differential sequence to determine the compensation frequency offset value comprises:

[0095] The baseband oversampling sync-head differential sequence and the local sync-head differential sequence are conjugate multiplied to determine a phase difference sequence; the phase difference sequence includes a phase difference corresponding to each sample point in the baseband oversampling sync-head differential sequence;

[0096] The phase differences in the phase difference sequence are processed by averaging to obtain a frequency offset value corresponding to a single correlation peak;

[0097] When a plurality of correlation peaks are continuously searched and index positions of peak values of the plurality of correlation peaks meet a preset locking state condition, it is determined that a locking state is reached, and an average of frequency offset values corresponding to the plurality of correlation peaks is taken as the compensation frequency offset value.

[0098] In some embodiments, the index positions of the peak values of the plurality of correlation peaks meet the preset locking state condition in that:

[0099] A difference value between any two of the index positions of the peak values of the plurality of correlation peaks is equal to a frame length of the second baseband oversampling data multiplied by sps.

[0100] The sps is the number of samples per symbol.

[0101] In some embodiments, the plurality of correlation peaks is three.

[0102] The correlation peak is a peak value in the cross-correlation sequence.

[0103] Specifically, the modulus of the obtained cross-correlation sequence is taken, and a correlation peak search is performed using a set threshold (i.e., a preset threshold). If no correlation peak is found, the cached data sequence is updated. Continue repeating the operations corresponding to formulas (3) and (4) above.

[0104] When a set of cached data sequences finds the first relevant peak greater than the threshold, the index position of the current peak is recorded as idx1, and the baseband oversampled differential sequence is started from idx1. q Take out N -1 length of data is used to obtain the baseband oversampled synchronization head differential sequence. q s .

[0105] q s Differential sequence with local synchronization header p Performing conjugate multiplication yields the sequence ,in And further obtain the phase difference sequence The following formula (5):

[0106] ;……(5);

[0107] The phase difference obtained from formula (5) is averaged to obtain the frequency offset value. as follows:

[0108] ;……(6);

[0109] Continue buffering the received oversampled baseband data, repeat the operations of formulas (3) and (4) and find the second and third related peaks, record the index positions of the peaks idx2 and idx3, and calculate the frequency offset value according to formulas (5) and (6). , If at this point, the pairwise differences of idx1, idx2, and idx3 are all equal to the frame length sps If the frequency offset is multiple, it is considered to be in a locked state, and the average of the frequency offsets from the three solutions is taken. This is used as a compensation frequency offset value for subsequent data and is converted into a directly related method.

[0110] The satellite signal symbol-level processing method described in this application further calculates the phase difference and averages it to obtain the frequency offset value, making the calculated compensated frequency offset value more accurate, thereby better solving the problem of decreased estimation accuracy of blind frequency offset estimation under low signal-to-noise ratio or high-order modulation.

[0111] In the step S305, the second baseband oversampling data is compensated for frequency offset based on the compensation frequency offset value, to obtain third baseband oversampling data.

[0112] In some embodiments, compensating for frequency offset of the second baseband oversampling data based on the frequency offset value to obtain third baseband oversampling data comprises:

[0113] The second baseband oversampling data is compensated for frequency offset based on the following formula (7):

[0114] ; … (7)

[0115] Wherein, represents the second baseband oversampling data, represents third baseband oversampling data obtained after compensation for frequency offset; the represents the compensation frequency offset value; the represents a parameter for ensuring continuity of phase, the initial value is 0, and is updated through the following formula (8): ; … (8).

[0116] That is, after frame synchronization locking, the frequency offset value is calculated by using the above formula (6) f dest , and the current received baseband oversampling data is compensated based on the above formula (7) and formula (8).

[0117] In the step S306, symbol synchronization processing and carrier recovery processing are performed in parallel on each frame of data in the third baseband oversampling data, to obtain single-sampling symbol data.

[0118] In some embodiments, symbol synchronization processing and carrier recovery processing are performed in parallel on each frame of data in the third baseband oversampling data, to obtain single-sampling symbol data, comprising:

[0119] The third baseband oversampling data is frame-processed based on the index result of frame synchronization, to obtain a plurality of data frames; the index result of frame synchronization includes an index position of a peak value of the correlation peak;

[0120] A plurality of CPU cores are called to perform symbol synchronization processing and carrier recovery processing in parallel on a plurality of data frames of the third baseband oversampling data, to obtain single-sampling symbol data.

[0121] The pre-framing and frequency offset estimation and compensation joint processing method in the satellite signal symbol level processing method described in the embodiments of the present application is simulated and verified as follows.

[0122] The 16APSK modulation mode is selected to generate symbol data, a root-raised cosine filter with a roll-off factor of 0.25, an impact length of 10 and sps=4 is used for shaping filtering, a random frequency offset is added, and the received data is obtained by simulating an AWGN channel with an SNR of 6dB. Meanwhile, the local base sequence (QPSK modulation) is up-sampled according to the above shaping filter.

[0123] Please refer to Figure 4 , Figure 4 The over-sampled baseband data direct correlation result is shown; by Figure 4 It can be seen that due to the influence of frequency offset, the received data and the local over-sampled synchronization header sequence are directly correlated without obvious correlation peaks, and the synchronization header start position cannot be found at this time, so the frequency offset cannot be estimated; the sampling FFT blind frequency offset estimation method has a sharp decline in estimation accuracy due to the existence of high-order modulation in the received data and the low signal-to-noise ratio.

[0124] Please refer to Figure 5 , Figure 5 The difference correlation method described in the embodiment of the application is shown; by Figure 5 It can be seen that the difference correlation method described in the embodiment of the application can accurately find the position of the synchronization header, and at this time the synchronization header can be used to estimate the frequency offset, thereby ensuring the accuracy of the coarse frequency offset estimation function.

[0125] Please refer to Figure 6 , Figure 6 The over-sampled baseband signal direct correlation result after frequency offset compensation by the frequency offset estimation method described in the embodiment of the application is shown; it can be seen that the frequency offset estimation method described in the embodiment of the application can accurately estimate the frequency offset value, with an error of less than 1e-2, thereby ensuring the accuracy of the coarse frequency offset estimation under the condition of low signal-to-noise ratio and high-order modulation, and the over-sampled data after frequency offset compensation can be directly correlated with the local over-sampled synchronization header sequence to find the accurate synchronization header position.

[0126] The satellite signal symbol-level processing method described in the embodiment of the application is different from the method of synchronizing the whole baseband over-sampled data first and then framing in the traditional processing flow. The synchronization header sequence is shaped and filtered to obtain an over-sampled synchronization header sequence, which is directly correlated with the baseband over-sampled data to perform early framing processing, independent symbol synchronization and subsequent carrier recovery of each frame of data are performed simultaneously by calling different CPU cores after obtaining each frame of independent data, thereby improving the processing efficiency.

[0127] The satellite signal symbol level processing method provided in the embodiments of the present application can effectively resist the influence of large frequency offset on correlation by performing differential operation on the oversampling synchronization head sequence and performing cross-correlation operation on the differential operation result and the oversampling baseband data.

[0128] The satellite signal symbol level processing method provided in the embodiments of the present application can effectively resist the influence of large frequency offset on correlation by performing differential operation on the oversampling synchronization head sequence and performing cross-correlation operation on the differential operation result and the oversampling baseband data.

[0129] Based on the same inventive concept, the embodiments of the present application also provide a satellite signal symbol level processing device corresponding to the satellite signal symbol level processing method. Since the principle of the device in the embodiments of the present application for solving the problem is similar to the satellite signal symbol level processing method described above, the implementation of the device can be referred to the implementation of the method, and the repeated parts will not be described here.

[0130] Please refer to Figure 7 , Figure 7 The structure schematic diagram of the electronic device is shown in the embodiments of the present application; as shown in Figure 7 , as shown in Figure 7 , the electronic device 700 includes a processor 702, a memory 701 and a bus, the memory 701 stores machine readable instructions executable by the processor 702, when the electronic device 700 runs, the processor 702 and the memory 701 communicate through the bus, the machine readable instructions are executed by the processor 702 to execute the steps of the satellite signal symbol level processing method.

[0131] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working process of the system and the device described above can refer to the corresponding process in the method embodiment, and will not be repeated in the present application. In the several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented by other means. The above-described device embodiments are only schematic, for example, the division of the modules is only a logical function division, and the actual implementation can have another division manner, for example, a plurality of modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed mutual elements can be indirect coupling or communication connection through some communication interface, device or module, which can be electrical, mechanical or other forms.

[0132] The modules described as separate components can or can not be physically separated, and the components shown as modules can or can not be physical units, i.e. can be located in one place or distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0133] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit.

[0134] If the functions are realized in the form of software function units and sold or used as independent products, they can be stored in a non-volatile computer readable storage medium executable by a processor. Based on this understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or part of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a platform server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The foregoing storage medium includes: U disk, mobile hard disk, ROM, RAM, magnetic disk or optical disk, and various storage program codes.

[0135] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A satellite signal symbol-level processing method, characterized in that, The method includes: The second baseband oversampled data is obtained by performing matched filtering on the first baseband oversampled data using a filter consistent with the one used at the transmitting end. The local synchronization header sequence of the transceiver agreement is oversampled to obtain a local oversampled synchronization header sequence with the same oversampling factor as the first baseband oversampled data. The local oversampled synchronization header sequence is subjected to pairwise conjugation to obtain a local synchronization header differential sequence, which is then differentially correlated with the baseband oversampled differential sequence obtained after pairwise conjugation of the second baseband oversampled data to obtain a cross-correlation sequence. The baseband oversampled sync header differential sequence is extracted from the baseband oversampled differential sequence based on the cross-correlation sequence, and the phase deviation between the baseband oversampled sync header differential sequence and the local sync header differential sequence is calculated to determine the compensation frequency offset value. Based on the compensation frequency offset value, the second baseband oversampled data is compensated for frequency offset to obtain the third baseband oversampled data; Each frame of data in the third baseband oversampled data is processed in parallel with symbol synchronization and carrier recovery to obtain single-sampled symbol data.

2. The satellite signal symbol-level processing method according to claim 1, characterized in that, The step of oversampling the local synchronization header sequence of the transceiver agreement to obtain a local oversampled synchronization header sequence with the same oversampling factor as the first baseband oversampled data includes: Based on the roll-off factor, impulse length, and oversampling factor at the transmitting end, the local synchronization header sequence of the transceiver agreement is shaped and filtered to obtain a local oversampled synchronization header sequence; the local oversampled synchronization header sequence has the same oversampling factor as the first baseband oversampled data.

3. The satellite signal symbol-level processing method according to claim 1, characterized in that, The process of performing pairwise conjugation on the local oversampled synchronization header sequence to obtain a local synchronization header differential sequence, and then performing differential correlation with the baseband oversampled differential sequence obtained after pairwise conjugation on the second baseband oversampled data, yields a cross-correlation sequence, including: Perform a conjugate multiplication operation on two adjacent sample points in the local oversampled synchronization header sequence to obtain the local synchronization header difference sequence; Based on the length of the local oversampled synchronization header sequence, a buffer data sequence of the same length is buffered from the second baseband oversampled data; Perform conjugate multiplication on two adjacent samples in the cached data sequence to obtain the cached data difference sequence; The local synchronization header difference sequence and the cached data difference sequence are cross-correlated to obtain a cross-correlation sequence.

4. The satellite signal symbol-level processing method according to claim 3, characterized in that, The step of retrieving the baseband oversampled synchronization header differential sequence from the baseband oversampled differential sequence based on the cross-correlation sequence includes: The cross-correlation sequence is modulo-trunculated, and a correlation peak search is performed on the modulo-trunculated cross-correlation sequence based on a preset threshold; If no relevant peak is found, the cached data sequence is updated; the update of the cached data sequence is based on sliding the entire second baseband oversampled data backward by one sample point; If a relevant peak is found, record the index position of the peak value of the relevant peak, and extract the baseband oversampled synchronization header differential sequence from the baseband oversampled differential sequence based on the index position.

5. The satellite signal symbol-level processing method according to claim 4, characterized in that, The calculation of the phase deviation between the baseband oversampled sync header differential sequence and the local sync header differential sequence to determine the compensation frequency offset value includes: The baseband oversampled synchronization header differential sequence and the local synchronization header differential sequence are multiplied by their conjugates to determine the phase difference sequence; the phase difference sequence includes the phase difference corresponding to each sample point in the baseband oversampled synchronization header differential sequence; The phase differences in the phase difference sequence are averaged to obtain the frequency offset value corresponding to a single correlation peak. When multiple related peaks are found consecutively and the index positions of the peak values ​​of the multiple related peaks meet the preset locking state conditions, the state is identified as locked, and the average of the frequency offset values ​​corresponding to the multiple related peaks is used as the compensation frequency offset value.

6. The satellite signal symbol-level processing method according to claim 5, characterized in that, The index positions of the peak values ​​of the multiple related peaks meet the preset locking condition as follows: The pairwise difference between the index positions of the peak values ​​of the multiple related peaks is equal to sps times the frame length of the second baseband oversampled data.

7. The satellite signal symbol-level processing method according to claim 5, characterized in that, The number of related peaks is three.

8. The satellite signal symbol-level processing method according to claim 1, characterized in that, Based on the frequency offset value, frequency offset compensation is performed on the second baseband oversampled data to obtain the third baseband oversampled data, including: Frequency offset compensation is performed on the second baseband oversampled data based on the following formula: in, Characterizing the second baseband oversampling data, The third baseband oversampled data obtained after frequency offset compensation; Characterizing the compensated frequency offset value; the The parameter characterizing the phase continuity is initialized to 0. .

9. The satellite signal symbol-level processing method according to claim 4, characterized in that, Each frame of data in the third baseband oversampled data is processed in parallel with symbol synchronization and carrier recovery to obtain single-sampled symbol data, including: The third baseband oversampled data is segmented into multiple data frames based on the frame synchronization index result; the frame synchronization index result includes the index position of the peak value of the correlation peak. Multiple CPU cores are invoked to perform symbol synchronization and carrier recovery processing in parallel on multiple data frames of the third baseband oversampled data to obtain single-sampled symbol data.

10. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the electronic device is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, they perform the steps of the satellite signal symbol-level processing method as described in any one of claims 1 to 9.

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