Signal demodulation method and device, satellite communication ground receiver and storage medium

Abstract

Embodiments of the present application provide a signal demodulation method and device, a satellite communication ground receiver and a storage medium, and relate to the field of satellite communication. The method is to realize accurate timing capture by performing coarse synchronization on the original received signal, and then to effectively solve the carrier loss problem caused by large amplitude Doppler frequency shift and its rate of change due to high-speed motion by combining frequency offset correction and dynamic frequency offset compensation. Then, by constructing a full-field phase compensation sequence and implementing point-by-point phase correction, the phase deviation changing with time is accurately recovered by using unwrapping and interpolation techniques, avoiding the interference caused by phase ambiguity to demodulation. Finally, on the basis of completing frequency and phase double fine correction, symbol decision and data demodulation are performed, which greatly reduces the bit error rate, enhances the robustness and reliability of the satellite communication system under extreme channel conditions, and realizes stable and efficient signal recovery under the scene of large frequency offset, high dynamics and low signal-to-noise ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of satellite communication, in particular to a signal demodulation method and device, a satellite communication ground receiver and a storage medium. BACKGROUND

[0002] In a satellite communication system, there is a significant relative velocity and acceleration between a ground receiver and a high-speed moving satellite, which results in a strong Doppler effect on the received signal. This effect manifests as a shift in carrier frequency (i.e., frequency offset) and the rate of change of the frequency offset over time, especially in high dynamic scenarios (such as low-orbit satellite fast over-the-top, spacecraft orbit transfer, etc.), the frequency offset and its rate of change can reach 1 / 3 of the symbol rate or even higher, which seriously affects the carrier synchronization performance of the receiver.

[0003] To achieve reliable demodulation, the receiver needs to accurately estimate and compensate for the frequency offset and phase deviation, but the prior art has deficiencies in frequency offset adaptation range, noise immunity, and phase estimation accuracy. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a signal demodulation method, device, satellite communication ground receiver and storage medium.

[0005] To achieve the above purpose, the technical solutions adopted by the embodiments of the present application are as follows:

[0006] In a first aspect, the present application provides a signal demodulation method applied to a satellite communication ground receiver, the method comprising:

[0007] Obtaining an original received signal and performing coarse synchronization processing on the original received signal to obtain a timing-synchronized signal;

[0008] Based on the timing-synchronized signal, obtaining a frequency-offset-corrected signal;

[0009] Based on the frequency-offset-corrected signal, obtaining a fully frequency-corrected signal;

[0010] Based on the fully frequency-corrected signal, obtaining a full-field phase compensation sequence;

[0011] Using the full-field phase compensation sequence to perform point-by-point phase correction on the fully frequency-corrected signal to obtain a fully corrected signal;

[0012] Based on the fully corrected signal, performing symbol decision and data demodulation.

[0013] Optionally, the step of performing coarse synchronization processing on the original received signal to obtain a timing-synchronized signal comprises:

[0014] sweeping the original received signal to obtain a signal with a preliminary reduced frequency offset;

[0015] performing a frame header capture operation on the signal with the preliminary reduced frequency offset according to a preset frame structure to obtain a frame start time;

[0016] performing a timing synchronization operation on the signal with the preliminary reduced frequency offset according to the frame start time to obtain a signal after timing synchronization.

[0017] Optionally, the step of obtaining a signal after frequency offset correction based on the signal after timing synchronization comprises:

[0018] performing filtering processing on the signal after timing synchronization to obtain a filtered signal;

[0019] reserving a frame header and a pilot section of the filtered signal, and setting a data block region between the frame header and the pilot section to zero to obtain a frequency offset estimation input signal;

[0020] performing frequency offset correction on the filtered signal based on the frequency offset estimation input signal to obtain a signal after frequency offset correction.

[0021] Optionally, the step of performing frequency offset correction on the filtered signal based on the frequency offset estimation input signal to obtain a signal after frequency offset correction comprises:

[0022] obtaining an initial frequency offset based on a position of a spectral peak with the largest amplitude in a frequency domain of the frequency offset estimation input signal;

[0023] generating a reverse complex exponential signal according to the initial frequency offset;

[0024] multiplying the complex exponential signal with the filtered signal to obtain the signal after frequency offset correction.

[0025] Optionally, the step of obtaining a completely frequency corrected signal based on the signal after frequency offset correction comprises:

[0026] obtaining a dynamic frequency offset change rate based on a frame header accumulation sum and a pilot section accumulation sum of the signal after frequency offset correction;

[0027] obtaining a frequency compensation sequence based on the initial frequency offset of the signal after frequency offset correction and the dynamic frequency offset change rate;

[0028] generating a complex exponential compensation factor according to the frequency compensation sequence;

[0029] multiplying the complex exponential compensation factor with the signal after frequency offset correction point by point to obtain the completely frequency corrected signal.

[0030] Optionally, the step of obtaining a full-field phase compensation sequence based on the completely frequency corrected signal comprises:

[0031] performing phase estimation on the fully frequency corrected signal to obtain a frame header phase angle sequence and a pilot phase angle sequence;

[0032] performing unwrapping processing on the frame header phase angle sequence and the pilot phase angle sequence to obtain a continuous phase sequence;

[0033] obtaining a full-field phase compensation sequence based on the continuous phase sequence.

[0034] Optionally, the step of obtaining the full-field phase compensation sequence based on the continuous phase sequence comprises:

[0035] performing interpolation processing on a data block region between a frame header and a pilot segment of the continuous phase sequence to generate the full-field phase compensation sequence.

[0036] In a second aspect, the present application provides a signal demodulation method applied to a satellite communication ground receiver, and the apparatus comprises:

[0037] an acquisition module configured to acquire an original received signal, and perform coarse synchronization processing on the original received signal to obtain a signal after timing synchronization;

[0038] a correction module configured to obtain a signal after frequency offset correction based on the signal after timing synchronization, obtain a fully frequency corrected signal based on the signal after frequency offset correction, obtain a full-field phase compensation sequence based on the fully frequency corrected signal, and perform point-by-point phase correction on the fully frequency corrected signal by using the full-field phase compensation sequence to obtain a fully corrected signal;

[0039] a demodulation module configured to perform symbol decision and data demodulation based on the fully corrected signal.

[0040] In a third aspect, the present application provides a satellite communication ground receiver comprising a processor and a memory, wherein the memory stores machine executable instructions capable of being executed by the processor, and the processor is capable of executing the machine executable instructions to implement the signal demodulation method of the first aspect.

[0041] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the signal demodulation method of the first aspect.

[0042] The signal demodulation method and device, satellite communication ground receiver and storage medium provided by the embodiment of the present application: an original received signal is acquired, and coarse synchronization processing is performed on the original received signal to obtain a signal after timing synchronization; a signal after frequency offset correction is obtained based on the signal after timing synchronization; a fully frequency corrected signal is obtained based on the signal after frequency offset correction; a full-field phase compensation sequence is obtained based on the fully frequency corrected signal; the fully frequency corrected signal is subjected to point-by-point phase correction by using the full-field phase compensation sequence to obtain a fully corrected signal; and symbol decision and data demodulation are performed based on the fully corrected signal. Since the embodiment of the present application realizes accurate timing capture by performing coarse synchronization on the original received signal, and then adopts a combination of frequency offset correction and dynamic frequency offset compensation, the problem of carrier loss caused by large Doppler frequency shift and its rate of change due to high-speed motion is effectively solved; then, by constructing a full-field phase compensation sequence and implementing point-by-point phase correction, the phase deviation changing with time is accurately restored by using unwrapping and interpolation technology, and the interference caused by phase ambiguity to demodulation is avoided; finally, symbol decision and data demodulation are performed on the basis of double fine correction of frequency and phase, the bit error rate is greatly reduced, the robustness and reliability of the satellite communication system under extreme channel conditions are enhanced, and stable and efficient signal recovery under the scene of large frequency offset, high dynamics and low signal-to-noise ratio is realized.

[0043] In order to make the above objectives, characteristics and advantages of the present application more apparent, clear and easy to understand, the following preferred embodiments are specifically described below with reference to the attached drawings. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used 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 on the basis of these drawings.

[0045] Figure 1 A structural schematic block diagram of a satellite communication ground receiver provided by the embodiment of the present application is shown;

[0046] Figure 2 A flowchart of a signal demodulation method provided by the embodiment of the present application is shown;

[0047] Figure 3 A frame structure diagram provided by the embodiment of the present application is shown;

[0048] Figure 4 A structural schematic diagram of a frequency offset estimation input signal provided by the embodiment of the present application is shown;

[0049] Figure 5A structure diagram of dynamic frequency offset data provided by the embodiment of the present application is shown.

[0050] Figure 6 A structure diagram of frequency correction signal provided by the embodiment of the present application is shown.

[0051] Figure 7 A bit error curve diagram of demodulated signal provided by the embodiment of the present application is shown.

[0052] Figure 8 A function module block diagram of signal demodulation device provided by the embodiment of the present application is shown.

[0053] Figures: 100-satellite communication ground receiver; 110-memory; 120-processor; 130-communication module; 200-signal demodulation device; 201-acquisition module; 202-correction module; 203-demodulation module. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0055] Therefore, the detailed description of the embodiments of the present application provided in the accompanying drawings below 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 work are within the scope of protection of the present application.

[0056] It should be noted that the relational terms such as "first" and "second" and the like are used only to distinguish one entity or action from another entity or action, and do not necessarily require or imply that these entities or actions have any such actual relationship or order. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or equipment including the element.

[0057] Please refer to Figure 1, is a structural schematic block diagram of the satellite communication ground receiver 100. The satellite communication ground receiver 100 includes a memory 110, a processor 120 and a communication module 130. The memory 110, the processor 120 and the communication module 130 are electrically connected with each other directly or indirectly to realize the transmission or interaction of data. For example, the elements can be electrically connected with each other through one or more communication buses or signal lines.

[0058] The memory 110 is configured to store programs or data. The memory 110 can be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read only memory (PROM), an erasable programmable read only memory (EPROM), an electric erasable programmable read only memory (EEPROM) and the like.

[0059] The processor 120 is configured to read / write the data or programs stored in the memory 110 and perform corresponding functions.

[0060] The communication module 130 is configured to establish a communication connection between the satellite communication ground receiver 100 and other communication terminals through the network, and configured to receive and transmit data through the network.

[0061] It should be understood that, Figure 1 The structure shown is only a structural schematic diagram of the satellite communication ground receiver 100, and the satellite communication ground receiver 100 can further include more or less components than those shown in the figure, or have a different configuration from that shown in the figure. Figure 1 The components shown in the figure can be realized by hardware, software or a combination thereof. Figure 1 The components shown in the figure can be realized by hardware, software or a combination thereof. Figure 1 The components shown in the figure can be realized by hardware, software or a combination thereof.

[0062] In a satellite communication system, due to the high-speed relative motion between the satellite and the ground terminal, the signal propagation process will be affected by a significant Doppler effect. This effect causes the frequency of the signal received at the receiving end to shift (i.e. frequency offset), and in a high dynamic scenario, the frequency offset changes rapidly with time, resulting in a non-zero frequency offset rate (i.e. dynamic frequency offset or frequency drift caused by acceleration). Especially in low-orbit satellite communication, high-speed aircraft or mobile terminal application scenarios, the Doppler frequency shift can reach several tenths of the symbol rate or even higher, which seriously damages the carrier synchronization process, leading to a sharp decline in demodulation performance, and even frequency lock failure.

[0063] To ensure the reliability of the communication link, the receiver needs to have accurate frequency offset estimation and compensation capability to achieve reliable demodulation. The existing frequency offset estimation algorithm is mainly divided into two categories: one is the method based on feedback loop, such as phase-locked loop and frequency-locked loop, which is suitable for continuous signal environment, but in burst communication mode, the convergence speed is slow, and it is difficult to meet the fast synchronization demand under short frame structure; the other is the open loop estimation algorithm designed for burst signal, including fast Fourier transform method, Kay algorithm, Fitz algorithm, L&R algorithm, M&M algorithm and cross-correlation estimation method.

[0064] However, these traditional algorithms have obvious limitations in high dynamic, extremely low signal-to-noise ratio satellite communication environment. For example, although the fast Fourier transform method has a wide estimation range, it is limited by the "fence effect", and its estimation accuracy depends on the number of fast Fourier transform points, which is difficult to achieve ideal resolution when the data length is limited; Kay algorithm has low complexity, but the estimation range is limited to ±0.5 symbol period, and the performance deteriorates rapidly when the signal-to-noise ratio is lower than 8dB; Fitz algorithm and L&R algorithm require small initial frequency offset, which cannot adapt to large frequency offset scenarios; M&M algorithm is sensitive to noise, and the estimation deviation is large under low signal-to-noise ratio condition; the cross-correlation method is also limited by the small frequency offset assumption, and it is difficult to cope with the dramatic frequency change caused by high dynamic.

[0065] In summary, the existing frequency offset estimation algorithm generally cannot balance the contradiction between large frequency offset range, high dynamic change characteristics and extremely low signal-to-noise ratio environment, especially in satellite burst communication system, there is a lack of a comprehensive solution that can still maintain high-precision estimation performance under large frequency offset (such as 1 / 3 of the symbol rate), high acceleration motion and low signal-to-noise ratio conditions.

[0066] In order to overcome the shortcomings of the prior art, the embodiments of the present application provide a signal demodulation method applied to a satellite communication ground receiver. The signal demodulation method realizes accurate compensation for large frequency offset, dynamic frequency offset and nonlinear phase change through a multi-stage joint estimation and correction mechanism, and significantly improves the demodulation performance. The signal demodulation method will be described in detail below.

[0067] Please refer to Figure 2 The signal demodulation method comprises steps S101-S106.

[0068] S101, the original received signal is obtained, and the original received signal is subjected to coarse synchronization processing to obtain a signal after timing synchronization.

[0069] In the high dynamic satellite communication scenario, the received signal is seriously affected by the Doppler effect, and the initial frequency offset can be more than 1 / 3 of the symbol rate, so direct demodulation will cause the carrier to lose lock. Therefore, coarse synchronization needs to be completed first to reduce the frequency burden of subsequent processing.

[0070] In a possible implementation, the implementation process of step S101 can be as follows:

[0071] S101-1, performing a frequency sweep operation on the original received signal to obtain a signal with a preliminary reduced frequency offset.

[0072] A plurality of local complex exponential sweep signals are generated at a certain step interval within a preset frequency range, are respectively conjugate multiplied with the original received signal and are integrated, a frequency point corresponding to the maximum energy is found, a preliminary frequency offset range is determined, and a reverse sweep signal is generated to down-convert the original signal to obtain a signal with a preliminary reduced frequency offset.

[0073] S101-2, performing a frame header capture operation on the signal with the preliminary reduced frequency offset according to a preset frame structure to obtain a frame start time.

[0074] The preset frame structure is as shown in Figure 3 includes a frame header with a length of N, a data block with a length of N1, and a pilot segment with a length of N2.

[0075] Based on the preset frame structure, the signal with the preliminary reduced frequency offset is subjected to correlation detection, the known frame header sequence is slidingly correlated with the received signal, and when the correlation value exceeds a set threshold, it is determined that the frame start position is captured, and the frame start time is obtained.

[0076] S101-3, performing a timing synchronization operation on the signal with the preliminary reduced frequency offset according to the frame start time to obtain a signal after timing synchronization.

[0077] The signal with the preliminary reduced frequency offset is accurately intercepted according to the frame start time, timing synchronization is completed, and the signal after timing synchronization is output.

[0078] The above coarse synchronization processing process of the original received signal effectively suppresses the symbol misplacement problem caused by large frequency offset, and lays a foundation for subsequent fine frequency offset estimation.

[0079] S102, obtaining a signal after frequency offset correction based on the signal after timing synchronization.

[0080] After coarse synchronization, the residual frequency offset has been reduced to a small range, but the main frequency offset component still needs to be further accurately estimated and corrected.

[0081] In a possible implementation, the implementation process of step S102 can be as follows:

[0082] S102-1, performing filtering processing on the signal after timing synchronization to obtain a filtered signal.

[0083] The signal after timing synchronization is subjected to filtering processing through a root-raised cosine matched filter to suppress out-of-band noise and improve the signal-to-noise ratio, and a filtered signal is obtained.

[0084] S102-2, reserve the frame header and pilot section of the filtered signal, and set the data block region between the frame header and the pilot section to zero, to obtain a frequency offset estimation input signal.

[0085] By reserving the frame header part (length N) and the pilot section (length N2) in the filtered signal, and setting the data block region (length N1) between the two to zero, a data structure as shown in Figure 4 is formed, thereby improving spectral concentration and facilitating improvement of fast Fourier transform frequency offset estimation accuracy.

[0086] S102-3, based on the frequency offset estimation input signal, performing frequency offset correction on the filtered signal to obtain a frequency offset corrected signal.

[0087] Further, the implementation process of step S102-3 can be: obtaining an initial frequency offset based on the position of the largest amplitude spectral peak in the frequency domain of the frequency offset estimation input signal; generating a reverse complex exponential signal based on the initial frequency offset; and multiplying the complex exponential signal with the filtered signal to obtain the frequency offset corrected signal.

[0088] In other words, the reconstructed signal is subjected to fast Fourier transform, the position of the largest amplitude spectral peak in the frequency domain is searched, and the initial frequency offset is calculated accordingly; then a complex exponential compensation signal exp(-j2πΔf0nT) corresponding to the frequency is generated, where n is the sample point index and T is the sampling period; and the complex exponential signal is multiplied point by point with the original filtered signal (unzeroed version) to complete the main frequency offset correction, and the frequency offset corrected signal is output.

[0089] The fast Fourier transform combined with data reconstruction can achieve wide-range and high-resolution frequency offset estimation under low signal-to-noise ratio conditions, and overcome the failure of traditional algorithms under large frequency offset or low signal-to-noise ratio conditions.

[0090] S103, based on the frequency offset corrected signal, obtaining a complete frequency corrected signal.

[0091] Although the main frequency offset has been eliminated, due to the existence of carrier acceleration, there may still be a dynamic frequency offset that changes linearly over time (i.e. frequency slope). Therefore, the dynamic component needs to be estimated and compensated.

[0092] In a possible implementation, the implementation process of step S103 can be as follows:

[0093] S103-1, obtaining a dynamic frequency offset change rate based on the frame header accumulation and the pilot section accumulation of the frequency offset corrected signal.

[0094] Extract the frame header cumulative sum A1 = Σx[i] (i ∈ frame header interval) and pilot segment cumulative sum A2 = Σx[j] (j ∈ pilot interval) from the frequency offset corrected signal.

[0095] Due to the cumulative operation to enhance signal energy, higher reliability can be maintained at low signal-to-noise ratio.

[0096] S103-2, based on the initial frequency offset of the frequency offset corrected signal and the dynamic frequency offset change rate, obtain the frequency compensation sequence.

[0097] Let the frame header start time be t1 and the pilot segment start time be t2, then the dynamic frequency offset change rate (frequency slope) k can be expressed as: k = (A2-A1) / (t2-t1).

[0098] Combine the initial frequency offset Δf0 obtained in the previous step to construct the total frequency compensation model: f(t) = Δf0+k(t-t1).

[0099] According to the above frequency model, a discretized frequency compensation sequence f[n] is generated within the entire frame duration.

[0100] S103-3, generate a complex exponential compensation factor according to the frequency compensation sequence.

[0101] Where, the complex exponential compensation factor C[n] = exp(-j2πΣf[n]T), the summation is cumulative form, which embodies the phase continuity.

[0102] S103-4, multiply the complex exponential compensation factor with the frequency offset corrected signal point by point to obtain the completely frequency corrected signal.

[0103] Multiply the compensation factor C[n] with the frequency offset corrected signal point by point to realize the full range correction of dynamic frequency, output the completely frequency corrected signal, and thus realize the effective tracking of linear frequency drift.

[0104] Exemplarily, as shown in the dynamic frequency offset data structure, Figure 5 , is the frame header data cumulative sum, is the pilot data cumulative sum.

[0105] Satisfy the following formula:

[0106] ,

[0107] ,

[0108] ,

[0109] , ,

[0110] The starting frequency offset is the ending frequency offset, interpolation calculation is made between to obtain the frequency compensation sequence , wherein Q is the total number of data frame symbols, , N is the number of data frame symbols of the frame header, N1 is the number of data frame symbols of the data block region, N2 is the number of data frame symbols of the pilot segment.

[0111] The frequency compensation sequence is used to generate a complex exponential compensation factor, and the generated complex exponential compensation factor is used to multiply the frequency offset corrected signal point by point to obtain a complete frequency correction signal as shown in Figure 6 .

[0112] S104, based on the complete frequency correction signal, obtain a full-field phase compensation sequence.

[0113] After frequency correction, there may still be slow phase drift in the signal caused by residual frequency error, local oscillator jitter or propagation path fluctuation, which needs to be estimated and interpolated compensated.

[0114] In possible implementations, the implementation process of step S104 can be as follows:

[0115] S104-1, phase estimation processing is performed on the complete frequency correction signal to obtain a frame header phase angle sequence and a pilot phase angle sequence.

[0116] The phase angles of each symbol of the frame header and the phase angles of each symbol of the pilot segment are extracted from the complete frequency correction signal to form the frame header phase angle sequence and the pilot phase angle sequence.

[0117] S104-2, unwrapping processing is performed on the frame header phase angle sequence and the pilot phase angle sequence to obtain a continuous phase sequence.

[0118] The frame header phase angle sequence and the pilot phase angle sequence are unwrapped. Since the phase angle has a 2π periodicity, direct use may cause jump mutation. By judging whether the difference between adjacent phase angles exceeds π, if it exceeds, 2π is automatically added or subtracted for correction to obtain a continuous and smooth phase sequence.

[0119] S104-3, based on the continuous phase sequence, obtain a full-field phase compensation sequence.

[0120] Further, the implementation process of step S104-3 can be: interpolation processing is performed on the data block region between the frame header and the pilot segment of the continuous phase sequence to generate a full-field phase compensation sequence.

[0121] In the time interval between the frame header and the pilot segment, the continuous phase sequence is extended using linear or spline interpolation method to generate a full-field phase compensation sequence covering the entire data frame.

[0122] Exemplarily, the phase Figure 6 of the frame header and the pilot segment are extracted from the full frequency correction signal as shown in , , , and the phase difference , , wherein, , is the symbol in the frame header, is the known symbol corresponding to the frame header, is the phase of the pilot segment, and the phase difference , , .

[0123] Then unwrapping: , , . The purpose of unwrapping is to flatten the phase angle and remove the influence of the period.

[0124] The , between them is obtained by interpolation method , and the subsequent data is interpolated to obtain the full-field phase compensation sequence , wherein, , , N is the number of data frame symbols of the frame header, N1 is the number of data frame symbols of the data block region, N2 is the number of data frame symbols of the pilot segment.

[0125] S105, using the full-field phase compensation sequence, the full frequency correction signal is phase-corrected point by point to obtain the full correction signal.

[0126] The full-field phase compensation sequence generated in step S104 is converted into a complex compensation factor, and is multiplied point by point with each symbol in the full frequency correction signal to remove the residual phase distortion, and the full correction signal is output.

[0127] S106, based on the full correction signal, symbol decision and data demodulation are performed.

[0128] The full correction signal is symbol mapped and hard-decision according to the modulation mode (such as BPSK, QPSK, etc.), the original transmission bit stream is recovered, and the data demodulation is completed. ​

[0129] The demodulation results can be used for bit error rate (BER) assessment, such as Figure 7 As shown, it can still maintain good demodulation performance under extremely low signal-to-noise ratio (such as below -2dB) and high dynamic conditions.

[0130] In summary, this embodiment solves the problems of inaccurate frequency offset estimation and severe phase mismatch in existing technologies under high dynamic and low signal-to-noise ratio environments by adopting a full-process collaborative design of frequency sweep coarse synchronization, fast Fourier transform large frequency offset estimation, dynamic frequency offset modeling, and unwinding full-field phase interpolation compensation. It significantly reduces demodulation loss and improves the stability and availability of satellite communication links.

[0131] To perform the corresponding steps in the above embodiments and various possible methods, an implementation of the signal demodulation device 200 is given below. Further, please refer to... Figure 8 , Figure 8 This is a functional block diagram of a signal demodulation device 200 provided in an embodiment of the present invention. It should be noted that the basic principle and technical effects of the signal demodulation device 200 provided in this embodiment are the same as those in the above embodiments. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the above embodiments. The signal demodulation device 200 includes:

[0132] The acquisition module 201 is used to acquire the original received signal and perform coarse synchronization processing on the original received signal to obtain the signal after time synchronization.

[0133] The correction module 202 is used to obtain a frequency offset corrected signal based on the signal after timing synchronization; obtain a fully frequency corrected signal based on the frequency offset corrected signal; obtain a full-field phase compensation sequence based on the fully frequency corrected signal; and perform point-by-point phase correction on the fully frequency corrected signal using the full-field phase compensation sequence to obtain a fully corrected signal.

[0134] The demodulation module 203 is used for symbol decision and data demodulation based on the fully corrected signal.

[0135] Optionally, the above modules can be stored in the form of software or firmware. Figure 1 The memory 110 shown is either stored in or embedded in the operating system (OS) of the satellite communication ground receiver 100, and can be used by... Figure 1 The processor 120 executes the program. Meanwhile, the data and program code required to execute the above modules can be stored in the memory 110.

[0136] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can also be implemented by other manners. The apparatus embodiments described above are merely illustrative, for example, the flowcharts and block diagrams in the drawings show the possible implementation architecture, function and operation of the apparatus, method and computer program product according to the embodiments of the present application. In this regard, each block in the flowcharts or block diagrams can represent a module, a program segment or a part of code, which contains one or more executable instructions for implementing the specified logic function. It should also be noted that in some alternative implementation manners, the functions noted in the blocks can also occur in different order from that noted in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and sometimes they can also be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and the combination of blocks in the block diagrams and / or flowcharts, can be implemented by a dedicated hardware-based system for executing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0137] In addition, each functional module in the embodiments of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0138] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part of the prior art that contributes to the technical solutions or the part of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0139] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A signal demodulation method characterized by comprising: The method is applied to a satellite communication ground receiver, and comprises the following steps: An original received signal is acquired, and coarse synchronization processing is performed on the original received signal to obtain a timing-synchronized signal; Based on the timing-synchronized signal, a frequency-offset-corrected signal is obtained; According to the frame header accumulation and the pilot accumulation of the frequency-offset-corrected signal, a dynamic frequency offset change rate is obtained; Based on the initial frequency offset of the frequency-offset-corrected signal and the dynamic frequency offset change rate, a frequency compensation sequence is obtained; A complex exponential compensation factor is generated according to the frequency compensation sequence; The complex exponential compensation factor is multiplied point by point with the frequency-offset-corrected signal to obtain a completely frequency-corrected signal; Phase estimation processing is performed on the completely frequency-corrected signal to obtain a frame header phase angle sequence and a pilot phase angle sequence; The frame header phase angle sequence and the pilot phase angle sequence are unwound to obtain a continuous phase sequence; An interpolation process is performed on a data block region between the frame header and the pilot of the continuous phase sequence to generate a full-field phase compensation sequence; The full-field phase compensation sequence is used to perform point-by-point phase correction on the completely frequency-corrected signal to obtain a completely corrected signal; Based on the completely corrected signal, symbol decision and data demodulation are performed.

2. The signal demodulation method of claim 1, wherein The step of performing coarse synchronization processing on the original received signal to obtain a timing-synchronized signal comprises the following steps: A frequency sweeping operation is performed on the original received signal to obtain a signal with a preliminarily reduced frequency offset; According to a preset frame structure, frame header capture operation is performed on the signal with a preliminarily reduced frequency offset to obtain a frame start time; Timing synchronization operation is performed on the signal with a preliminarily reduced frequency offset according to the frame start time to obtain a timing-synchronized signal.

3. The signal demodulation method of claim 1, wherein The step of obtaining a frequency-offset-corrected signal based on the timing-synchronized signal comprises the following steps: Filtering processing is performed on the timing-synchronized signal to obtain a filtered signal; The frame header and the pilot of the filtered signal are retained, and the data block region between the frame header and the pilot is set to zero to obtain a frequency offset estimation input signal; Based on the frequency offset estimation input signal, frequency offset correction is performed on the filtered signal to obtain a frequency-offset-corrected signal.

4. The signal demodulation method of claim 3, wherein The step of performing frequency offset correction on the filtered signal based on the frequency offset estimation input signal to obtain a frequency-offset-corrected signal comprises the following steps: According to the position of the spectral peak with the largest amplitude in the frequency domain of the frequency offset estimation input signal, an initial frequency offset is obtained; According to the initial frequency offset, a reverse complex exponential signal is generated; The reverse complex exponential signal is multiplied with the filtered signal to obtain a frequency-offset-corrected signal.

5. A signal demodulation apparatus characterized by comprising: The device is applied to a satellite communication ground receiver, and comprises the following modules: An acquisition module is configured to acquire an original received signal, and perform coarse synchronization processing on the original received signal to obtain a timing-synchronized signal; The correction module is configured to obtain a frequency offset corrected signal based on the timing-synchronized signal, obtain a dynamic frequency offset variation rate according to a frame header accumulation sum and a pilot accumulation sum of the frequency offset corrected signal, obtain a frequency compensation sequence based on an initial frequency offset of the frequency offset corrected signal and the dynamic frequency offset variation rate, generate a complex exponential compensation factor according to the frequency compensation sequence, multiply the complex exponential compensation factor with the frequency offset corrected signal point by point to obtain a completely frequency corrected signal, perform phase estimation processing on the completely frequency corrected signal to obtain a frame header phase angle sequence and a pilot phase angle sequence, perform unwrapping processing on the frame header phase angle sequence and the pilot phase angle sequence to obtain a continuous phase sequence, perform interpolation processing on a data block region between the frame header and the pilot of the continuous phase sequence to generate a full-field phase compensation sequence, and perform point-by-point phase correction on the completely frequency corrected signal using the full-field phase compensation sequence to obtain a completely corrected signal. The demodulation module is configured to perform symbol decision and data demodulation based on the completely corrected signal.

6. A satellite communications ground receiver, characterized by The computer program is executed by the processor to implement the signal demodulation method according to any one of claims 1-4.

7. A computer-readable storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to implement the signal demodulation method according to any one of claims 1-4.

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