Data link signal synchronization and rate identification methods, devices, equipment and media

Abstract

This invention provides a method, apparatus, device, and medium for data link signal synchronization and rate identification, relating to the field of communications. The method includes: acquiring a complex baseband signal of a data link signal; generating first and second complex signal templates corresponding to first and second frame lengths, each containing a carrier with a synchronization tone frequency and a phase transition at the boundary of each frame; performing sliding correlation processing on the complex baseband signal and the first and second complex signal templates respectively, and normalizing the correlation results to obtain first and second normalized correlation curves; performing peak search on the first and second normalized correlation curves respectively, and performing cross-curve matching to determine burst synchronization points; comparing the peak scores of the two normalized correlation curves at the burst synchronization points to determine the burst rate pattern. This invention enables robust burst detection, automatic rate pattern identification, and frame synchronization of data link signals under low signal-to-noise ratio, frequency offset, and interference environments.

Description

Technical Field

[0001] This invention relates to the field of communications, and more particularly to a method, apparatus, device, and medium for synchronizing and identifying the rate of a data link signal. Background Technology

[0002] Link-11 is a traditional tactical data link primarily used for ship-to-ship and ship-to-air combat command and intelligence transmission. Its key feature is the use of analog audio channels to transmit voice and data, and it can operate in both HF (High Frequency) and UHF (Ultra High Frequency) bands. The Link-11 data link incorporates encryption devices, providing a degree of security, but its data transmission rate is relatively low and it lacks anti-jamming capabilities. However, Link-11 can use the HF band and has cross-horizon communication capabilities. Link-11A is a mesh half-duplex data link that uses the conventional Link-11 waveform CLEW (Conventional Link Eleven Waveform) for data exchange. It employs a parallel transmission system and standard information format, using π / 4-DQPSK (π / 4-shifted Differential Quadrature Phase Shift Keying) modulation. Multiple single-audio parallel bearers and differential phase modulation are used in the baseband to form frame-based data, supporting two bit rate modes. In actual reception processing, burst detection, synchronization, and rate pattern recognition are required for the Link-11 CLEW signal.

[0003] Currently, the detection and synchronization of Link-11 CLEW signals typically employs a method that uses the frequency domain to detect the synchronization signal frequency point. First, an energy-based dual-window sliding burst detection algorithm is used to extract the IQ segment containing the signal from the baseband IQ (In-phase and Quadrature) data stream. Then, a sliding FFT (Fast Fourier Transform) is performed with a window length of 13.33ms, and the frequency domain energy distribution is obtained by taking the square of the modulus, detecting the 2915Hz synchronization frequency component. Finally, under two frame lengths of 13.33ms and 22ms, the minimum energy value and its position are found within the first four frame windows. The sum of the minimum values ​​for the two modes is compared; the smaller value corresponds to the rate, and the position of the minimum value is the midpoint of that frame. This method relies on serial time-domain energy extraction, sliding FFT, and heuristic extreme value localization. It suffers from poor robustness in real-world environments with low signal-to-noise ratios, frequency offsets, interference, and changes in front-end gain, making it difficult to achieve robust detection and synchronization under unknown rate modes.

[0004] Therefore, how to achieve robust burst detection, automatic rate pattern recognition, and frame synchronization of Link-11 CLEW signals under low signal-to-noise ratio, frequency offset, and interference environments is a problem that urgently needs to be solved. Summary of the Invention

[0005] This invention provides a method, apparatus, device, and medium for data link signal synchronization and rate identification, which enables robust burst detection, automatic rate pattern identification, and frame synchronization of data link signals under low signal-to-noise ratio, frequency offset, and interference environments.

[0006] This invention provides a method for synchronizing and identifying the rate of a data link signal, comprising: Acquire the complex baseband signal of the data link signal; A first complex signal template and a second complex signal template corresponding to the first frame length and the second frame length are generated respectively. Both the first complex signal template and the second complex signal template contain a carrier with a frequency of synchronous single tone, and each frame boundary has a phase jump. The complex baseband signal is subjected to sliding correlation processing with the first complex signal template and the second complex signal template respectively, and the correlation results are normalized to obtain the first normalized correlation curve and the second normalized correlation curve. Peak search is performed on the first normalized correlation curve and the second normalized correlation curve respectively, and cross-curve matching is performed based on the obtained candidate peak position set to determine the sudden synchronization point; The peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point are compared, and the burst rate pattern is determined based on the comparison results.

[0007] According to a data link signal synchronization and rate identification method provided by the present invention, the method involves performing sliding correlation processing on the complex baseband signal with the first complex signal template and the second complex signal template, respectively, and normalizing the correlation results to obtain a first normalized correlation curve and a second normalized correlation curve, including: The complex baseband signal is subjected to sliding correlation processing with the first complex signal template to obtain a first correlation value corresponding to each sliding position, and the energy of a first data segment of the complex baseband signal with a length of the first signal length is calculated at each sliding position; the first signal length is calculated based on the first frame length. Based on the squared amplitude of the first correlation value, the length of the first signal, and the energy of the first data segment, a first normalized correlation value is calculated, and a first normalized correlation curve is generated based on the first normalized correlation value. The complex baseband signal is subjected to sliding correlation processing with the second complex signal template to obtain the second correlation value corresponding to each sliding position, and the energy of the second data segment of the complex baseband signal with a length of the second signal length at each sliding position is calculated; the second signal length is calculated based on the second frame length. Based on the squared amplitude of the second correlation value, the second signal length, and the energy of the second data segment, a second normalized correlation value is calculated, and a second normalized correlation curve is generated based on the second normalized correlation value.

[0008] According to the data link signal synchronization and rate identification method provided by the present invention, the step of calculating a first normalized correlation value based on the amplitude square of the first correlation value, the length of the first signal, and the energy of the first data segment includes: Calculate the first product of the first signal length and the energy of the first data segment, and add the first product to a preset positive number to obtain the first denominator value; The first normalized correlation value is obtained by squared the magnitude of the first correlation value and dividing it by the first denominator value.

[0009] According to a data link signal synchronization and rate identification method provided by the present invention, the step of performing peak search on the first normalized correlation curve and the second normalized correlation curve respectively, and performing cross-curve matching based on the obtained candidate peak position set to determine the burst synchronization point includes: The first candidate peak of the first normalized correlation curve is detected, and the first candidate peak is suppressed by minimum spacing to obtain the set of positions of the first candidate peak. The second candidate peak of the second normalized correlation curve is detected, and the second candidate peak is suppressed by minimum spacing to obtain the set of second candidate peak positions; the first candidate peak and the second candidate peak are local maxima points with amplitudes not lower than a preset threshold; If there exists a pair of candidate peaks in the first set of candidate peak positions and the second set of candidate peak positions where the position difference between the candidate peaks is less than the preset window width, then the candidate peak pair is determined to belong to the same burst, and the burst synchronization point is determined based on the position of the candidate peak pair.

[0010] According to the data link signal synchronization and rate identification method provided by the present invention, the step of performing minimum spacing suppression on the first candidate peak to obtain the first candidate peak position set includes: Traverse the first candidate peak in chronological order; If the distance between the current candidate peak and the previous selected peak is less than a preset spacing threshold, then the peak with the larger amplitude between the current candidate peak and the previous selected peak will replace the previous selected peak in the selected peak list. If the distance between the current candidate peak and the previous selected peak is greater than or equal to a preset spacing threshold, then the current candidate peak is added to the selected peak list. The list of selected peaks at the end of the traversal is used as the set of the first candidate peak positions.

[0011] According to a data link signal synchronization and rate identification method provided by the present invention, the step of comparing the peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point, and determining the burst rate pattern based on the comparison result, includes: On the first normalized correlation curve and the second normalized correlation curve, a neighborhood window centered on the burst synchronization point is taken respectively, and the maximum peak value within the neighborhood window is taken as the peak score; The burst rate mode is determined based on the frame length corresponding to the normalized correlation curve with the higher peak score.

[0012] According to the data link signal synchronization and rate identification method provided by the present invention, the step of generating a first complex signal template and a second complex signal template corresponding to a first frame length and a second frame length, respectively, includes: Based on the sampling rate, calculate the first number of samples per frame and the first signal length corresponding to the first frame length; Based on the sampling rate, calculate the second number of samples per frame and the second signal length corresponding to the second frame length; Based on the synchronous single-tone frequency and the first number of samples per frame, a first complex signal template with a length equal to the length of the first signal is generated, wherein the first complex signal template has a π phase transition superimposed at the boundary of each frame; Based on the synchronous single-tone rate and the second number of samples per frame, a second complex signal template with a length equal to the length of the second signal is generated, wherein the second complex signal template has a π phase transition superimposed at the boundary of each frame.

[0013] The present invention also provides a data link signal synchronization and rate identification device, comprising: The data link signal processing module is used to acquire the complex baseband signal of the data link signal; The complex signal template generation module is used to generate a first complex signal template and a second complex signal template corresponding to the first frame length and the second frame length, respectively. Both the first complex signal template and the second complex signal template contain a carrier with a frequency of synchronous single tone, and each frame boundary has a phase jump. The sliding correlation and normalization module is used to perform sliding correlation processing on the complex baseband signal with the first complex signal template and the second complex signal template respectively, and normalize the correlation results to obtain the first normalized correlation curve and the second normalized correlation curve. The sudden synchronization point determination module is used to perform peak search on the first normalized correlation curve and the second normalized correlation curve respectively, and perform cross-curve matching based on the obtained candidate peak position set to determine the sudden synchronization point; The rate pattern determination module is used to compare the peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point, and determine the burst rate pattern based on the comparison results.

[0014] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the data link signal synchronization and rate identification method as described above.

[0015] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the data link signal synchronization and rate identification method as described in any of the preceding claims.

[0016] This invention provides a method, apparatus, device, and medium for data link signal synchronization and rate identification. It acquires the complex baseband signal of the data link signal and simultaneously generates a first complex signal template and a second complex signal template corresponding to a first frame length and a second frame length, respectively. Both the first and second complex signal templates contain a carrier with a synchronization tone frequency and have a phase transition at the boundary of each frame. Then, the complex baseband signal is subjected to sliding correlation processing with the first and second complex signal templates, and the correlation results are normalized to obtain a first normalized correlation curve and a second normalized correlation curve. This invention directly performs sliding correlation after acquiring the complex baseband signal, replacing the serial process of performing time-domain energy pre-detection followed by sliding FFT in the prior art. This eliminates the dependence on energy thresholds and avoids missed cuts and boundary offsets caused by noise fluctuations or improper thresholds. It also eliminates the impact of spectral leakage and frequency shifts caused by misaligned FFT frequency grids on detection performance. Furthermore, by normalizing the correlation results, the output normalized correlation curve is independent of the amplitude of the complex baseband signal, and front-end gain or equipment differences will no longer affect subsequent decisions. Next, peak searches are performed on the first and second normalized correlation curves, and cross-curve matching is conducted based on the obtained candidate peak position set to determine the burst synchronization point. Because the complex signal template generated by this invention has precise phase transitions at each frame boundary, the correlation results exhibit sharp peaks when the sliding window is aligned with the actual preamble. Compared to the traditional assumption of locating the frame midpoint based on the minimum energy value, this invention utilizes a determined phase structure to obtain a more stable and noise-resistant burst synchronization point. Finally, the peak scores of the first and second normalized correlation curves at the burst synchronization point are compared, and the burst rate mode is determined based on the comparison results. The entire process does not require prior knowledge of the rate mode; synchronization position and rate information can be output simultaneously in a single scan, avoiding the inefficient process of assuming the rate first and then trying and failing in traditional methods, thus improving the robustness and efficiency of the processing. In summary, without performing time-domain energy pre-detection / truncation or sliding FFT, this invention directly achieves rate pattern recognition and frame synchronization in a single scan through a series of processes including complex baseband acquisition, dual template generation, sliding correlation and normalization, peak search and cross-curve matching, and score comparison at burst synchronization points, even in environments with low signal-to-noise ratio, frequency offset, interference, and amplitude variations. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1This is one of the flowcharts illustrating the data link signal synchronization and rate identification method provided by the present invention.

[0019] Figure 2 This is the second flowchart illustrating the data link signal synchronization and rate identification method provided by this invention.

[0020] Figure 3 This is the third flowchart of the data link signal synchronization and rate identification method provided by the present invention.

[0021] Figure 4 These are the time-domain power spectrum and frequency-domain power spectrum of the complex signal template corresponding to a frame length of 13.33ms provided by this invention.

[0022] Figure 5 This invention provides the time-domain power spectrum and frequency-domain power spectrum of a complex baseband signal.

[0023] Figure 6 This is one of the schematic diagrams of the normalized correlation curve provided by the present invention.

[0024] Figure 7 This invention provides Figure 6 A magnified view of the normalized correlation curve shown.

[0025] Figure 8 This is the second schematic diagram of the normalized correlation curve provided by the present invention.

[0026] Figure 9 This is a schematic diagram of the data link signal synchronization and rate identification device provided by the present invention.

[0027] Figure 10 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] Link-11 is a traditional tactical data link primarily used for ship-to-ship and ship-to-air combat command and intelligence transmission. Its key feature is the use of analog audio channels to transmit voice and data, and it can operate in both HF (High Frequency) and UHF (Ultra High Frequency) bands. The Link-11 data link incorporates encryption devices, providing a degree of security, but its data transmission rate is relatively low and it lacks anti-jamming capabilities. However, Link-11 can use the HF band and has cross-horizon communication capabilities. Link-11A is a mesh half-duplex data link that uses the conventional Link-11 waveform CLEW (Conventional Link Eleven Waveform) for data exchange. It employs a parallel transmission system and standard information format, using π / 4-DQPSK (π / 4-shifted Differential Quadrature Phase Shift Keying) modulation. Multiple single-audio parallel bearers and differential phase modulation are used in the baseband to form frame-based data, supporting two bit rate modes. In actual reception processing, burst detection, synchronization, and rate pattern recognition are required for the Link-11 CLEW signal.

[0030] Currently, the detection and synchronization of Link-11 CLEW signals typically employs a method that uses the frequency domain to detect the synchronization signal frequency point: First, an energy-based dual-window sliding burst detection algorithm is used on the baseband IQ data stream to extract the IQ segment containing the signal; then, a sliding FFT is performed with a window length of 13.33ms, and the frequency domain energy distribution is obtained by taking the square of the modulus, detecting the 2915Hz synchronization frequency component; finally, under two frame lengths of 13.33ms and 22ms, the minimum energy value and its position are found within the first four frame windows, and the magnitude of the "sum of minimum values" of the two modes is compared. The smaller value corresponds to the rate, and the position of the minimum value is the midpoint of that frame.

[0031] This method has the following drawbacks in practical applications: (1) It is sensitive to time-domain energy pre-detection, which can easily lead to synchronization failure. The energy detection threshold needs to be set manually and is extremely sensitive to noise fluctuations and signal amplitude changes. Once the truncation boundary is shifted or missed, the subsequent sliding FFT, extreme value location and rate decision will all be distorted. Especially after the signal is windowed and smoothed, frame synchronization often shows sample-level shifts. (2) The assumption that "the minimum value is the midpoint of the frame" is unreliable. This method uses the position of the minimum energy value within the sliding window as the midpoint of the frame, which is highly dependent on the window shape and noise / interference pattern. When there is frequency offset, non-stationary noise or impulse interference, the extreme value position will drift significantly, resulting in frame demarcation deviation, which in turn affects the accuracy of rate determination; (3) Susceptible to interference and false alarms. Broadband pulse interference, narrowband pulse interference or adjacent frequency interference can all cause local energy surges, which are misjudged as burst signals by time-domain energy detection and thus enter the back-end calculation, which not only wastes processing resources, but also increases the overall false alarm rate of the system.

[0032] In summary, existing methods rely on serial time-domain energy truncation, sliding FFT, and heuristic extremum localization. They are not robust in real-world environments with low signal-to-noise ratios, frequency offsets, interference, and changes in front-end gain, making it difficult to achieve robust detection and synchronization under unknown rate modes.

[0033] Therefore, how to achieve robust burst detection, automatic rate pattern recognition, and frame synchronization of Link-11 CLEW signals under low signal-to-noise ratio, frequency offset, and interference environments is a problem that urgently needs to be solved.

[0034] Based on the above problems, this invention proposes a method, apparatus, device, and medium for data link signal synchronization and rate identification. The following describes the process in conjunction with... Figures 1-10 Describe it.

[0035] Figure 1 This is one of the flowcharts illustrating the data link signal synchronization and rate identification method provided by the present invention, such as... Figure 1 As shown, the data link signal synchronization and rate identification method includes steps S110, S120, S130, S140 and S150.

[0036] Step S110: Obtain the complex baseband signal of the data link signal.

[0037] The data link signal is the Link-11 data link signal transmitted through the wireless channel, which contains CLEW waveform information and is in modulated carrier mode.

[0038] If the data link signal is in complex baseband form, it is directly used as a complex baseband signal.

[0039] If the data link signal is a real-valued RF or IF signal, the data link signal is first demodulated to obtain a real baseband signal; then, the real baseband signal is subjected to a Hilbert transform to construct a complex baseband signal.

[0040] Step S120: Generate a first complex signal template and a second complex signal template corresponding to the first frame length and the second frame length, respectively. Both the first complex signal template and the second complex signal template contain a carrier with a frequency of synchronous single tone, and each frame boundary has a phase transition.

[0041] The two bit rate modes (i.e. rate modes) of Link-11 CLEW correspond to different frame lengths: (1) the fast rate corresponds to a frame length of 13.33ms; (2) the slow rate corresponds to a frame length of 22ms.

[0042] The first frame length and the second frame length are the frame lengths corresponding to the two bit rates supported by Link-11 CLEW, respectively. In this embodiment of the invention, the example is taken with a first frame length of 13.33ms and a second frame length of 22ms.

[0043] The generation process of the first complex signal template is as follows: Based on the sampling rate, calculate the number of first sample points per frame and the length of the first signal corresponding to the first frame length; based on the synchronous single-tone frequency and the number of first sample points per frame, generate a first complex signal template with a length equal to the length of the first signal, wherein the first complex signal template has a π phase transition superimposed at the boundary of each frame.

[0044] Similarly, the generation process of the second complex signal template is as follows: based on the sampling rate, calculate the number of second samples per frame and the second signal length corresponding to the second frame length; based on the synchronous single-tone frequency and the number of samples per frame, generate a second complex signal template with a length equal to the second signal length, wherein the second complex signal template has a π phase transition superimposed at the boundary of each frame.

[0045] The synchronous single-tone frequency is set to 2915Hz as specified in the protocol. The specific generation process of the first and second complex signal templates can be found in the following embodiment, and will not be elaborated upon here.

[0046] Step S130: Perform sliding correlation processing on the complex baseband signal with the first complex signal template and the second complex signal template respectively, and normalize the correlation results to obtain the first normalized correlation curve and the second normalized correlation curve.

[0047] The complex baseband signal is subjected to sliding correlation processing with the first complex signal template to obtain the first correlation value corresponding to each sliding position. The first correlation value is then normalized to obtain the first normalized correlation curve.

[0048] Simultaneously, the complex baseband signal and the second complex signal template are subjected to sliding correlation processing to obtain the second correlation value corresponding to each sliding position, and the second correlation value is normalized to obtain the second normalized correlation curve.

[0049] Step S140: Perform peak search on the first normalized correlation curve and the second normalized correlation curve respectively, and perform cross-curve matching based on the obtained candidate peak position set to determine the burst synchronization point.

[0050] In one embodiment, a first candidate peak of the first normalized correlation curve is detected as a first candidate peak position set; at the same time, a second candidate peak of the second normalized correlation curve is detected as a second candidate peak position set; if there is a candidate peak pair in the first candidate peak position set and the second candidate peak position set where the position difference between the candidate peaks is less than the preset window width, then the candidate peak pair is determined to belong to the same burst, and the burst synchronization point is determined based on the position of the candidate peak pair.

[0051] In another embodiment, a first candidate peak of the first normalized correlation curve is detected, and minimum spacing suppression is applied to the first candidate peak to obtain a set of first candidate peak positions; simultaneously, a second candidate peak of the second normalized correlation curve is detected, and minimum spacing suppression is applied to the second candidate peak to obtain a set of second candidate peak positions; the first candidate peak and the second candidate peak are local maxima points with amplitudes not lower than a preset threshold; if there is a pair of candidate peaks in the first candidate peak position set and the second candidate peak position set where the position difference between the candidate peaks is less than a preset window width, then the candidate peak pair is determined to belong to the same burst, and the burst synchronization point is determined based on the position of the candidate peak pair.

[0052] The specific execution process can be found in the following examples, which will not be elaborated here.

[0053] Step S150: Compare the peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point, and determine the burst rate mode based on the comparison results.

[0054] For each burst synchronization point, the peak scores of the first normalized correlation curve and the second normalized correlation curve at that burst synchronization point are compared, and the burst rate pattern is determined based on the comparison results.

[0055] In one embodiment, a neighborhood window centered on the burst synchronization point is taken on the first normalized correlation curve and the second normalized correlation curve, respectively, and the maximum peak value within the neighborhood window is taken as the peak score; the burst rate mode is determined based on the frame length corresponding to the normalized correlation curve with the higher peak score.

[0056] The data link signal synchronization and rate identification method provided in this invention acquires the complex baseband signal of the data link signal and simultaneously generates a first complex signal template and a second complex signal template corresponding to a first frame length and a second frame length, respectively. Both the first and second complex signal templates contain a carrier with a synchronization tone frequency and have a phase transition at the boundary of each frame. Then, the complex baseband signal is subjected to sliding correlation processing with the first and second complex signal templates, and the correlation results are normalized to obtain a first normalized correlation curve and a second normalized correlation curve. This invention directly performs sliding correlation after acquiring the complex baseband signal, replacing the serial process of performing time-domain energy pre-detection followed by sliding FFT in the prior art. This eliminates the dependence on energy thresholds and avoids missed cuts and boundary offsets caused by noise fluctuations or improper thresholds. It also eliminates the impact of spectral leakage and frequency shift caused by misaligned FFT frequency grids on detection performance. Furthermore, by normalizing the correlation results, the output normalized correlation curve is independent of the amplitude of the complex baseband signal, and front-end gain or device differences will no longer affect subsequent decisions. Next, peak searches are performed on the first and second normalized correlation curves, and cross-curve matching is performed based on the obtained candidate peak position set to determine the burst synchronization point. Because the complex signal template generated in this embodiment of the invention has precise phase transitions at each frame boundary, the correlation results exhibit sharp peaks when the sliding window is aligned with the actual preamble. Compared to the traditional assumption of locating the frame midpoint based on the minimum energy value, this embodiment of the invention utilizes a determined phase structure to obtain a more stable and noise-resistant burst synchronization point. Finally, the peak scores of the first and second normalized correlation curves at the burst synchronization point are compared, and the burst rate mode is determined based on the comparison results. The entire process does not require prior knowledge of the rate mode; synchronization position and rate information can be output simultaneously in a single scan, avoiding the inefficient process of assuming the rate first and then trying and failing in traditional methods, thus improving the robustness and efficiency of the processing. In summary, the embodiments of the present invention, without performing time-domain energy pre-detection / truncation or sliding FFT, directly achieve rate pattern recognition and frame synchronization in a single scan through a series of processes including complex baseband acquisition, dual template generation, sliding correlation and normalization, peak search and cross-curve matching, and score comparison at burst synchronization points, even in environments with low signal-to-noise ratio, frequency offset, interference, and amplitude variations.

[0057] Based on any of the above embodiments, step S110 includes: step S111 and step S112.

[0058] Step S111: If the data link signal is a real-valued radio frequency or intermediate frequency signal, demodulate the data link signal to obtain a real baseband signal.

[0059] If the data link signal is a real-valued radio frequency (RF) or intermediate frequency (IF) signal, that is, the data link signal is a real-valued RF or IF sequence, it is denoted as...r [ n ].

[0060] For data link signals r [ n Demodulation is performed to obtain the real baseband signal, denoted as... .

[0061] In one embodiment, if the received data link signal is AM (Amplitude Modulation), i.e., a Link-11 signal modulated by AM, then envelope detection is used to obtain... y [ n ].

[0062] In another embodiment, if the received data link signal is FM (Frequency Modulation), i.e., a Link-11 signal modulated by FM, then the frequency discriminator obtains... .

[0063] Step S112: Perform Hilbert transform on the real baseband signal to obtain the complex baseband signal.

[0064] Then, for the real baseband signal Perform Hilbert transform to construct the complex baseband signal The details are as follows: ; in, j H represents the imaginary unit, and H represents the Hilbert transform. Indicates to The result of performing the Hilbert transform.

[0065] The data link signal synchronization and rate identification method provided in this embodiment of the invention converts the actual received AM / FM real signal into a complex baseband signal in the above manner, so that subsequent matching correlation can utilize the complete phase information of the signal, especially the phase transition characteristics, thereby improving the synchronization accuracy.

[0066] Based on any of the above embodiments, step S120 includes: step S121, step S122, step S123 and step S124.

[0067] It should be noted that the execution order of steps S121 and S122 is not important, and the execution order of steps S123 and S124 is not important; they can be executed in parallel.

[0068] Step S121: Based on the sampling rate, calculate the number of first sample points per frame and the first signal length corresponding to the first frame length.

[0069] Step S122: Based on the sampling rate, calculate the second number of samples per frame and the second signal length corresponding to the second frame length.

[0070] The sampling rate refers to the sampling rate of the receiver. The first signal length is the total number of preamble samples corresponding to the first frame length, and the second signal length is the total number of preamble samples corresponding to the second frame length.

[0071] The two bit rate modes (i.e. rate modes) of Link-11 CLEW correspond to different frame lengths: (1) the fast rate corresponds to a frame length of 13.33ms; (2) the slow rate corresponds to a frame length of 22ms.

[0072] The first frame length and the second frame length are the frame lengths corresponding to the two bit rates supported by Link-11 CLEW, respectively. In this embodiment of the invention, the first frame length is used... T high The duration is 13.33ms, and the second frame length is... T low Let's take 22ms as an example for explanation.

[0073] Based on the sampling rate and the first frame length, calculate the corresponding number of samples per frame (denoted as the first number of samples per frame) and the signal length (denoted as the first signal length). Simultaneously, based on the sampling rate and the second frame length, calculate the corresponding number of samples per frame (denoted as the second number of samples per frame) and the signal length (denoted as the second signal length).

[0074] For each frame length ( R Indicates the rate mode, for high or low First, the number of samples per frame is calculated. The first and second number of samples per frame are calculated using the following formula: in, This represents the number of samples per frame. Indicates the sampling rate. Indicates the frame length. It should be understood that when... R express high hour, That is, the length of the first frame. That is, the number of samples per frame in the first frame; when R express low hour, That is, the length of the second frame. That is, the number of samples per frame for the second time.

[0075] Then, the signal length is calculated. Since the preamble consists of 5 frames, the first and second signal lengths are calculated using the following formula: .

[0076] in, Indicates the signal length. Similarly, when R express high hour, That is, the length of the first signal; when R express low hour, That is, the second signal length.

[0077] Step S123: Based on the synchronous single-tone frequency and the first number of samples per frame, generate a first complex signal template with a length equal to the length of the first signal, wherein the first complex signal template has a π phase transition superimposed at the boundary of each frame.

[0078] Step S124: Based on the synchronous single-tone frequency and the second number of samples per frame, generate a second complex signal template with a length equal to the length of the second signal, wherein the second complex signal template has a π phase transition superimposed at the boundary of each frame.

[0079] Synchronous Monophonic Rate .

[0080] The first complex signal template is a complex exponential sequence with a length equal to the length of the first signal. Its instantaneous phase is composed of two superimposed parts: the first part is the phase generated by continuous rotation of the synchronous single-tone frequency. The second part is the π phase transition superimposed at the boundary of each frame, which is controlled by the frame number function.

[0081] Similarly, the second complex signal template is a complex exponential sequence with a length equal to the second signal length, and its instantaneous phase is composed of two superimposed parts: the first part is the phase generated by continuous rotation of the synchronous monotone frequency. The second part is the π phase transition superimposed at the boundary of each frame, which is controlled by the frame number function.

[0082] The first and second complex signal templates are generated through the following process: First, define the frame number function as follows: ; in, Representing sample points The frame number it belongs to. This represents the discrete-time sample index, and it indicates rounding down to the nearest integer.

[0083] Then, construct the instantaneous phase: ; in, Indicates the first n The instantaneous phase of each sample point This means that the phase increases by an additional amount with each frame. (i.e., a 180° jump).

[0084] The complex signal template is: .

[0085] in, Let exp represent the template for a complex signal, and let exp represent the natural exponential function. j It represents the imaginary unit.

[0086] It should be noted that in the actual link, the preamble also contains a 605Hz Doppler tone, but this embodiment of the invention only uses the synchronization tone for correlation matching. The π phase transition at the boundary of each frame contained in the template precisely corresponds to the feature of the 2915Hz tone in the protocol undergoing a 180° phase transition at the end of each frame, which enables the subsequent sliding correlation to generate sharp peaks, thereby accurately locking the frame start point.

[0087] The data link signal synchronization and rate identification method provided in this invention uses a complex signal template generated in the above manner to accurately simulate the frequency of the 2915Hz synchronization tone in the Link-11 CLEW preamble and the π phase transition at each frame boundary. This means that when the complex baseband signal is correlated with this complex signal template, a sharp peak will only appear if the sliding window completely covers the preamble and the frame boundaries are aligned. Even a single sample point of alignment deviation will cause a significant decrease in the correlation value. This sensitivity to phase transitions significantly improves synchronization accuracy and resistance to frequency offset compared to traditional methods that rely solely on 2915Hz energy detection.

[0088] Based on any of the above embodiments Figure 2 This is the second flowchart illustrating the data link signal synchronization and rate identification method provided by this invention, as shown below. Figure 2 As shown, step S130 includes: step S131, step S132, step S133 and step S134.

[0089] It should be noted that the execution order of steps S131-S132 and steps S133-S134 is not important and they can be executed in parallel.

[0090] Step S131: Perform sliding correlation processing on the complex baseband signal and the first complex signal template to obtain the first correlation value corresponding to each sliding position, and calculate the energy of the first data segment of the complex baseband signal with a length of the first signal length starting from each sliding position; the first signal length is calculated based on the first frame length.

[0091] First, the complex baseband signal and the first complex signal template are subjected to sliding correlation processing to obtain the correlation value corresponding to each sliding position, which is recorded as the first correlation value.

[0092] Specifically, in the entire section Slide upwards, for each starting position of the slide n ( n (Indicates the sample index of the current sliding window's starting position), and takes a data segment of the complex baseband signal with a length equal to the first signal length. ,and For matching correlation, the convolution kernel is... The formula is as follows: ; in, Indicates the relevant value; k This represents the relative offset index within the window, with values ​​in [0, ..., ...]. ]; Indicates complex conjugation.

[0093] Then, the energy of the complex baseband signal at each sliding position, with a data segment of length equal to the length of the first signal, is calculated and denoted as the energy of the first data segment. The formula is as follows: ; in, Indicates the energy of the data segment. Representing complex numbers The model.

[0094] Step S132: Calculate a first normalized correlation value based on the squared amplitude of the first correlation value, the length of the first signal, and the energy of the first data segment; and generate the first normalized correlation curve based on the first normalized correlation value.

[0095] Based on the squared amplitude of the first correlation value, the length of the first signal, and the energy of the first data segment, a normalized correlation value is calculated and denoted as the first normalized correlation value.

[0096] In one embodiment, the first product of the first signal length and the energy of the first data segment is calculated as the first denominator value; the square of the amplitude of the first correlation value is divided by the first denominator value to obtain the first normalized correlation value.

[0097] In another embodiment, a first product of the first signal length and the energy of the first data segment is calculated, and the first product is added to a preset positive number to obtain a first denominator value; the square of the amplitude of the first correlation value is divided by the first denominator value to obtain a first normalized correlation value. By adding the preset positive number, division by zero can be avoided.

[0098] Then, a normalized correlation curve independent of amplitude scaling is generated based on the first normalized correlation value, denoted as the first normalized correlation curve.

[0099] Step S133: Perform sliding correlation processing on the complex baseband signal and the second complex signal template to obtain the second correlation value corresponding to each sliding position, and calculate the energy of the second data segment of the complex baseband signal with a length of the second signal length starting from each sliding position; the second signal length is calculated based on the second frame length.

[0100] First, the complex baseband signal is subjected to sliding correlation processing with the second complex signal template to obtain the correlation value corresponding to each sliding position, which is denoted as the second correlation value. Then, the energy of the data segment of the complex baseband signal with a length equal to the length of the second signal is calculated at each sliding position, and denoted as the second data segment energy.

[0101] The calculation method for the second correlation value is similar to that for the first correlation value, and the calculation method for the energy of the second data segment is similar to that for the energy of the first data segment. Please refer to the corresponding execution process and implementation formula mentioned above.

[0102] Step S134: Calculate a second normalized correlation value based on the squared amplitude of the second correlation value, the second signal length, and the energy of the second data segment; and generate a second normalized correlation curve based on the second normalized correlation value.

[0103] Based on the squared amplitude of the second correlation value, the second signal length, and the energy of the second data segment, a normalized correlation value is calculated and denoted as the second normalized correlation value. Then, a normalized correlation curve is generated based on the second normalized correlation value and denoted as the second normalized correlation curve.

[0104] The calculation method for the second normalized correlation value is similar to that for the first normalized correlation value. The generation methods for the second normalized correlation curve and the first normalized correlation curve can be found in the corresponding execution process and implementation formulas described above.

[0105] The data link signal synchronization and rate identification method provided in this embodiment of the invention obtains two normalized correlation curves through the above-described sliding correlation and normalization processing. During normalization, the normalized correlation value is calculated based on the square of the correlation value's amplitude, the signal length, and the data segment energy, ensuring that the normalized correlation curve is independent of the absolute amplitude of the complex baseband signal. This eliminates the influence of automatic gain control (AGC) or amplitude differences between different receiving devices.

[0106] Based on any of the above embodiments, the step "calculate the first normalized correlation value based on the square of the amplitude of the first correlation value, the length of the first signal, and the energy of the first data segment" includes: steps S1321 and S1322.

[0107] Step S1321: Calculate the first product of the first signal length and the first data segment energy, and add the first product to a preset positive number to obtain the first denominator value.

[0108] Calculate the product of the first signal length and the energy of the first data segment, and record it as the first product. Add the first product to a preset positive number to obtain the denominator value, and record it as the first denominator value.

[0109] In this embodiment of the invention, the preset positive number is a very small positive number, which is much smaller than the energy term of the data segment, for example, 10. -6 The magnitude can be selected as any suitable, extremely small positive number based on the actual calculation precision and signal dynamic range. Adding it to a preset positive number prevents the denominator from being zero in division operations.

[0110] Step S1322: Squaring the magnitude of the first correlation value and dividing it by the first denominator value to obtain the first normalized correlation value.

[0111] Then, the square of the magnitude of the first correlation value is divided by the first denominator value to obtain the normalized correlation value, which is denoted as the first normalized correlation value.

[0112] The specific implementation formula is as follows: ; in, Indicates the normalized correlation value; This represents the squared magnitude of the correlation value; This indicates a preset positive number.

[0113] The data link signal synchronization and rate identification method provided in this embodiment of the invention obtains a normalized correlation value by dividing the sum of the squared amplitude of the correlation value as the numerator and the product of the complex baseband signal window energy (i.e., data segment energy) and the template length with a preset positive number as the denominator. The normalized correlation value calculated in this way is independent of the absolute amplitude of the complex baseband signal. When receiver front-end AGC or gain changes cause changes in the complex baseband signal... x [ n When the whole is magnified, the numerator will be magnified by the same factor, while the denominator will be magnified by the same factor. It will also amplify by the same factor, so the ratio remains unchanged, eliminating the effects of front-end gain control (AGC) or amplitude differences between different receiving devices. This allows it to operate at the same fixed threshold without needing to recalibrate for different recordings or devices. Furthermore, adding a very small positive number ensures that even... No division by zero error will occur when =0 (no signal segment).

[0114] Based on any of the above embodiments Figure 3 This is the third flowchart illustrating the data link signal synchronization and rate identification method provided by this invention, as shown below. Figure 3 As shown, step S140 includes: step S141, step S142 and step S143.

[0115] It should be noted that the execution order of steps S141 and S142 is not important and they can be executed in parallel.

[0116] Step S141: Detect the first candidate peak of the first normalized correlation curve, and perform minimum spacing suppression on the first candidate peak to obtain the set of first candidate peak positions.

[0117] The candidate peaks of the first normalized correlation curve are detected and denoted as the first candidate peak. The first candidate peak is a local maximum point whose amplitude is not lower than a preset threshold.

[0118] When detecting candidate peaks, all indices can be traversed. n ,like ,and Then determine the current index. i The corresponding position is a candidate peak. Indicates the current index i The corresponding normalized correlation value; This indicates the preset threshold, which can be set to 0.3; Indicates index The corresponding normalized correlation value; Indicates index The corresponding normalized correlation value.

[0119] It should be noted that for the first and last points (i.e. i= 0 and i=L R 1 o'clock ）， Then it only compares with its only neighbor: when i= At 0 o'clock, if ,and If it is, then it is determined as a candidate peak.

[0120] when i= At that time, if ,and If it is, then it is determined as a candidate peak.

[0121] Minimum spacing suppression is applied to the first candidate peak to obtain the set of candidate peak positions, denoted as the first candidate peak position set.

[0122] Specifically, the first candidate peaks are traversed in chronological order. If the distance between the current candidate peak and the previous selected peak is less than a preset distance threshold, the peak with the larger amplitude is used to replace the previous selected peak in the selected peak list. If the distance between the current candidate peak and the previous selected peak is greater than or equal to the preset distance threshold, the current candidate peak is added to the selected peak list. The selected peak list at the end of the traversal is used as the set of positions for the first candidate peaks. The specific execution process can be found in the following embodiment, which will not be elaborated here.

[0123] Step S142: Detect the second candidate peak of the second normalized correlation curve, and perform minimum spacing suppression on the second candidate peak to obtain the set of second candidate peak positions; the first candidate peak and the second candidate peak are local maxima points with amplitudes not lower than a preset threshold.

[0124] Using the aforementioned candidate peak detection method, candidate peaks of the second normalized correlation curve are detected and denoted as the second candidate peak. The second candidate peak is a local maximum point whose amplitude is not lower than a preset threshold.

[0125] Then, minimum spacing suppression is applied to the second candidate peak to obtain the set of candidate peak positions, denoted as the second candidate peak position set. The process of determining the second candidate peak position set is similar to that of determining the first candidate peak position set, and can be referred to the above embodiment.

[0126] Step S143: If there is a candidate peak pair in the first candidate peak position set and the second candidate peak position set where the position difference between the candidate peaks is less than the preset window width, then the candidate peak pair is determined to belong to the same burst, and the burst synchronization point is determined based on the position of the candidate peak pair.

[0127] The preset window width can be set based on a first number of samples per frame and / or a second number of samples per frame. In one embodiment, the smaller value of the first number of samples per frame and the second number of samples per frame is obtained and multiplied by a preset coefficient (e.g., 0.5) to obtain the preset window width. W .

[0128] For the set of locations of the first candidate peak (denoted as...) P high Each peak position in ) (denoted as ), the set of second candidate peak locations (denoted as P low The peak position (denoted as) Search in ) and The distance between them is less than W Candidate peak pairs that satisfy this distance condition belong to the same burst.

[0129] Then, burst synchronization points are determined based on the positions of candidate peak pairs.

[0130] In one embodiment, the average value of the positions of the two candidate peaks in a candidate peak pair is taken as the position of the burst synchronization point, denoted as . The details are as follows: .

[0131] Furthermore, for a certain No match They still consider it an unexpected event. Similarly, for P low Unmatched peaks are also considered as sudden occurrences. Ultimately, a list of all sudden synchronization points is obtained.

[0132] The data link signal synchronization and rate identification method provided in this invention uses minimum spacing suppression to merge multiple local maxima within each burst into a single peak, avoiding repeated detection of multiple synchronization points for the same burst. Furthermore, cross-curve matching leverages the characteristic that both rate templates exhibit peak values ​​(with different amplitudes) near the correct synchronization point. By setting a preset window width, it achieves co-domain association of candidate peaks from both rate templates, preventing incorrect peak pairing from different bursts.

[0133] Based on any of the above embodiments, step S141 includes: step S1411, step S1412, step S1413 and step S1414.

[0134] Step S1411: Traverse the first candidate peak in chronological order.

[0135] Initialize an empty list of selected peaks P 1 is used to store the selected peak positions and initialize variables. pos ( end ) is empty, where, pos ( end () indicates the position of the previous selected peak.

[0136] Traverse the first candidate peak in chronological order.

[0137] Step S1412: If the distance between the current candidate peak and the previous selected peak is less than a preset spacing threshold, then replace the position of the previous selected peak in the selected peak list with the one with the larger amplitude between the current candidate peak and the previous selected peak.

[0138] If there is no previously selected peak, that is pos ( end If ) is empty, the current candidate peak is added to the list of selected peaks.

[0139] If the distance between the current candidate peak and the previous selected peak is less than a preset distance threshold, then the amplitudes of the current candidate peak and the previous selected peak are compared. The peak with the larger amplitude is then used to replace the previous selected peak in the selected peak list. That is, if the amplitude of the current candidate peak is larger than that of the previous selected peak, the previous selected peak is replaced with the current candidate peak; if the amplitude of the previous selected peak is larger than that of the current candidate peak, the previous selected peak is retained, and the current candidate peak is discarded.

[0140] The preset spacing threshold is set based on the signal length. When determining the first candidate peak position set, the preset spacing threshold is set based on the first signal length; when determining the second candidate peak position set, the preset spacing threshold is set based on the second signal length.

[0141] The formula for calculating the preset spacing threshold is as follows: ; in, This indicates the preset spacing threshold. This indicates rounding down to the nearest integer.

[0142] Step S1413: If the distance between the current candidate peak and the previous selected peak is greater than or equal to a preset spacing threshold, then the current candidate peak is added to the selected peak list.

[0143] If the distance between the current candidate peak and the previous selected peak is greater than or equal to the preset spacing threshold, then the current candidate peak is added to the list of selected peaks.

[0144] Step S1414: The list of selected peaks at the end of the traversal is used as the first candidate peak position set.

[0145] Finally, when the traversal is complete, the list of selected peaks at this point is used as the set of the first candidate peak positions.

[0146] The data link signal synchronization and rate identification method provided in this embodiment of the invention ensures that each burst outputs only one peak, and retains the one with the highest amplitude, through the aforementioned rule of replacing the nearest peak with the highest amplitude. Since the spacing between candidate peaks within the same burst is much smaller than the preset spacing threshold, while the distance between different bursts is usually greater than the preset spacing threshold, this rule can effectively suppress the multi-peak phenomenon caused by template correlation, avoiding false alarms and missed alarms.

[0147] Based on any of the above embodiments, step S150 includes: step S151 and step S152.

[0148] Step S151: On the first normalized correlation curve and the second normalized correlation curve, take a neighborhood window centered on the burst synchronization point, and take the maximum peak value within the neighborhood window as the peak score.

[0149] For each sudden synchronization point Define the neighborhood window radius r On the first and second normalized correlation curves respectively, a neighborhood window centered on the current burst synchronization point is taken, denoted as W( ), W ( )for .

[0150] In one embodiment, the radius of the neighborhood window can be the product of the number of samples per frame corresponding to the smaller of the first and second frame lengths and a preset value (e.g., 20%). r Of course, the radius of the neighborhood window can also be adjusted according to the actual signal-to-noise ratio. r The typical value ranges from 10% to 30% of the number of samples per frame.

[0151] Then, the maximum peak value (i.e., the maximum normalized correlation value) within the neighborhood window is calculated as the peak score. It should be understood that the peak score includes the first peak score corresponding to the neighborhood window of the first normalized correlation curve and the second peak score corresponding to the neighborhood window of the second normalized correlation curve. The first and second peak scores are determined by the following formula: ; in, Peak score; m Integer index, used to traverse the neighborhood window W ( The location of each sample point within ); In rate mode R, the index m The normalized correlation value at the location.

[0152] Step S152: Determine the burst rate mode based on the frame length corresponding to the normalized correlation curve with the higher peak score.

[0153] Then, based on the frame length corresponding to the normalized correlation curve with the higher peak score, the burst rate mode is determined. Specifically: ; in, Indicates a sudden synchronization point The corresponding burst rate mode; Indicates the length of the second frame T low The corresponding rate; Indicates the length of the first frame T high The corresponding rate.

[0154] The data link signal synchronization and rate identification method provided in this invention determines the rate by comparing the correlation peak scores of two templates within the same neighborhood window, avoiding potential biases introduced by cross-segment comparisons. Since the two normalized correlation curves are calculated for the same complex baseband signal segment, their background noise and interference conditions are identical, ensuring fairness in the comparison results. Furthermore, the neighborhood window design tolerates minor time alignment errors that may exist between the two curves, improving the robustness of the rate determination.

[0155] Furthermore, the frame length corresponding to the normalized correlation curve with the higher peak score (denoted as ) is determined. T frame After that, calculate the number of samples per frame. N frame , N frame =F s ×T frame The protocol specifies that the preamble length is 5 frames; therefore, the total number of preamble samples is... for: .

[0156] Based on the total number of samples in the preamble and the previously determined burst synchronization points Determine the starting sample index for the data field. for: Subsequent processing (such as demodulation and decoding) can then be performed from... start.

[0157] Furthermore, if there are multiple burst synchronization points, then for each burst synchronization point, the starting sample index of the corresponding data field is calculated to form a list of starting sample indexes for the data field.

[0158] Furthermore, the experimental data verification of the technical solution of this invention is as follows. Test conditions include: Link-11 CLEW signals collected in reality, processed into complex baseband signals, and a sampling rate of... =256.5kHz, signal rate mode is 13.33ms.

[0159] First, the complex signal template (i.e., the local preamble template) corresponding to the signal rate pattern 13.33ms is generated, and its time-domain power spectrum and frequency-domain power spectrum are as follows: Figure 4 As shown.

[0160] Because it is a complex single-tone signal, the time-domain power spectrum has a constant envelope. The peak frequencies of the frequency-domain power spectrum are 2880Hz and 2955Hz, instead of the synchronization signal frequency of 2915Hz. This is because the frequency grid of the FFT used to plot the power spectrum does not include 2915Hz, resulting in spectral leakage. This also illustrates the advantage of the method in this embodiment of the invention not relying on directly reading the power value at a fixed frequency point of the FFT, and eliminating the need to consider the problem of inaccurate power values ​​at the 2915Hz frequency point due to misalignment of the FFT frequency grid or spectral leakage.

[0161] The time-domain power spectrum and frequency-domain power spectrum of the received CLEW complex baseband signal are as follows: Figure 5 As shown, energy can be observed at the 16 frequency points specified in the protocol. This indicates that the received signal conforms to the protocol characteristics and can be used for subsequent testing.

[0162] The complex signal template and complex baseband signal, processed according to the 13.33ms rate mode, were subjected to sliding correlation and normalization, followed by peak search. The threshold for the normalized correlation value was set to 0.3. The normalized correlation curve is shown below. Figure 6 As shown. Figure 6 The vertical axis represents the normalized correlation value, and the horizontal axis represents the sample point number. Points marked with circles represent the correlation value of each sample point, and the circles indicate the searched correlation peaks, i.e., the locations of synchronization bursts. (Continued...) Figure 7 and Figure 8 That's also true.

[0163] Bundle Figure 6 Zooming in on a specific area will show detailed relevant information and search results, such as... Figure 7 As shown, there are 5 CLEW signal segments within this time period, each with a preamble. A CLEW signal undergoes sliding correlation with the complex signal template, resulting not in a single peak, but rather 3-5 maxima with a period of one frame. This is the reason for minimum spacing suppression during peak search in this embodiment of the invention; if only the maxima are taken, misjudgment would occur, thus requiring a restricted peak search.

[0164] The generated signal rate pattern is a 22ms complex signal template, which is then subjected to sliding correlation and normalization with the complex baseband signal, followed by peak search. The normalized correlation value is as follows: Figure 8 As shown, the normalized correlation value is no more than 0.12, which is far below the threshold of 0.3. Compared with the correlation value corresponding to the complex signal template of 13.33ms, it is very small. Therefore, it can be determined that the actual signal operating rate is 13.33ms instead of 22ms.

[0165] The synchronization and rate identification device for data link signals provided by the present invention will be described below. The data link signal synchronization and rate identification device described below can be referred to in correspondence with the data link signal synchronization and rate identification method described above.

[0166] Figure 9 This is a schematic diagram of the data link signal synchronization and rate identification device provided by the present invention, as shown below. Figure 9 As shown, the device includes a data link signal processing module 910, a complex signal template generation module 920, a sliding correlation and normalization module 930, a burst synchronization point determination module 940, and a rate pattern determination module 950; wherein: The data link signal processing module 910 is used to acquire the complex baseband signal of the data link signal; The complex signal template generation module 920 is used to generate a first complex signal template and a second complex signal template corresponding to the first frame length and the second frame length, respectively. Both the first complex signal template and the second complex signal template contain a carrier with a frequency of synchronous single tone, and each frame boundary has a phase jump. The sliding correlation and normalization module 930 is used to perform sliding correlation processing on the complex baseband signal with the first complex signal template and the second complex signal template respectively, and normalize the correlation results to obtain the first normalized correlation curve and the second normalized correlation curve. The sudden synchronization point determination module 940 is used to perform peak search on the first normalized correlation curve and the second normalized correlation curve respectively, and perform cross-curve matching based on the obtained candidate peak position set to determine the sudden synchronization point. The rate pattern determination module 950 is used to compare the peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point, and determine the burst rate pattern based on the comparison results.

[0167] The data link signal synchronization and rate identification device provided in this embodiment of the invention acquires the complex baseband signal of the data link signal and simultaneously generates a first complex signal template and a second complex signal template corresponding to a first frame length and a second frame length, respectively. Both the first and second complex signal templates contain a carrier with a synchronization tone frequency and have a phase transition at the boundary of each frame. Then, the complex baseband signal is subjected to sliding correlation processing with the first and second complex signal templates, and the correlation results are normalized to obtain a first normalized correlation curve and a second normalized correlation curve. This embodiment of the invention directly performs sliding correlation after acquiring the complex baseband signal, replacing the serial process of performing time-domain energy pre-detection followed by sliding FFT in the prior art. This eliminates the dependence on energy thresholds and avoids missed cuts and boundary offsets caused by noise fluctuations or improper thresholds. It also eliminates the impact of spectral leakage and frequency point offset caused by misalignment of the FFT frequency grid on detection performance. Furthermore, by normalizing the correlation results, the output normalized correlation curve is independent of the amplitude of the complex baseband signal, and front-end gain or equipment differences will no longer affect subsequent decisions. Next, peak searches are performed on the first and second normalized correlation curves, and cross-curve matching is performed based on the obtained candidate peak position set to determine the burst synchronization point. Since the complex signal template generated in this embodiment has precise phase transitions at each frame boundary, the correlation result exhibits sharp peaks when the sliding window is aligned with the actual preamble. Compared to the traditional assumption of locating the frame midpoint based on the minimum energy, this embodiment utilizes a determined phase structure to obtain a more stable and noise-resistant burst synchronization point. Finally, the peak scores of the first and second normalized correlation curves at the burst synchronization point are compared, and the burst rate mode is determined based on the comparison results. The entire process does not require prior knowledge of the rate mode; synchronization position and rate information can be output simultaneously in a single scan, avoiding the inefficient process of assuming the rate first and then trying and failing in traditional methods, thus improving the robustness and efficiency of the processing. In summary, the embodiments of the present invention, without performing time-domain energy pre-detection / truncation or sliding FFT, directly achieve rate pattern recognition and frame synchronization in a single scan through a series of processes including complex baseband acquisition, dual template generation, sliding correlation and normalization, peak search and cross-curve matching, and score comparison at burst synchronization points, even in environments with low signal-to-noise ratio, frequency offset, interference, and amplitude variations.

[0168] According to the present invention, a data link signal synchronization and rate identification device is provided, wherein the sliding correlation and normalization module 930 includes: The first sliding correlation processing unit is used to perform sliding correlation processing on the complex baseband signal and the first complex signal template to obtain a first correlation value corresponding to each sliding position, and to calculate the energy of a first data segment of the complex baseband signal with a length of the first signal length starting from each sliding position; the first signal length is calculated based on the first frame length. The first correlation curve generation unit is used to calculate a first normalized correlation value based on the square of the amplitude of the first correlation value, the length of the first signal, and the energy of the first data segment, and to generate the first normalized correlation curve based on the first normalized correlation value. The second sliding correlation processing unit is used to perform sliding correlation processing on the complex baseband signal and the second complex signal template to obtain a second correlation value corresponding to each sliding position, and to calculate the energy of a second data segment of the complex baseband signal with a length equal to the second signal length starting from each sliding position; the second signal length is calculated based on the second frame length. The second correlation curve generation unit is used to calculate a second normalized correlation value based on the square of the amplitude of the second correlation value, the second signal length, and the energy of the second data segment, and to generate the second normalized correlation curve based on the second normalized correlation value.

[0169] According to the data link signal synchronization and rate identification device provided by the present invention, the first sliding correlation processing unit is specifically used for: Calculate the first product of the first signal length and the energy of the first data segment, and add the first product to a preset positive number to obtain the first denominator value; The first normalized correlation value is obtained by squared the magnitude of the first correlation value and dividing it by the first denominator value.

[0170] According to the present invention, a data link signal synchronization and rate identification device is provided, wherein the burst synchronization point determination module 940 includes: The first candidate peak screening unit is used to detect the first candidate peak of the first normalized correlation curve and perform minimum spacing suppression on the first candidate peak to obtain the first candidate peak position set. The second candidate peak screening unit is used to detect the second candidate peak of the second normalized correlation curve and perform minimum spacing suppression on the second candidate peak to obtain the set of second candidate peak positions; the first candidate peak and the second candidate peak are local maxima points with amplitudes not lower than a preset threshold. The burst synchronization point determination unit is used to determine that if there is a candidate peak pair in the first candidate peak position set and the second candidate peak position set where the position difference between the candidate peaks is less than the width of a preset window, the candidate peak pair belongs to the same burst, and the burst synchronization point is determined based on the position of the candidate peak pair.

[0171] According to the data link signal synchronization and rate identification device provided by the present invention, the first candidate peak screening unit is specifically used for: Traverse the first candidate peak in chronological order; If the distance between the current candidate peak and the previous selected peak is less than a preset spacing threshold, then the peak with the larger amplitude between the current candidate peak and the previous selected peak will replace the previous selected peak in the selected peak list. If the distance between the current candidate peak and the previous selected peak is greater than or equal to a preset spacing threshold, then the current candidate peak is added to the selected peak list. The list of selected peaks at the end of the traversal is used as the set of the first candidate peak positions.

[0172] According to the present invention, a data link signal synchronization and rate identification device is provided, wherein the rate mode determination module 950 is specifically used for: On the first normalized correlation curve and the second normalized correlation curve, a neighborhood window centered on the burst synchronization point is taken respectively, and the maximum peak value within the neighborhood window is taken as the peak score; The burst rate mode is determined based on the frame length corresponding to the normalized correlation curve with the higher peak score.

[0173] According to the present invention, a data link signal synchronization and rate identification device is provided, wherein the complex signal template generation module 920 is specifically used for: Based on the sampling rate, calculate the first number of samples per frame and the first signal length corresponding to the first frame length; Based on the sampling rate, calculate the second number of samples per frame and the second signal length corresponding to the second frame length; Based on the synchronous single-tone frequency and the first number of samples per frame, a first complex signal template with a length equal to the length of the first signal is generated, wherein the first complex signal template has a π phase transition superimposed at the boundary of each frame; Based on the synchronous single-tone rate and the second number of samples per frame, a second complex signal template with a length equal to the length of the second signal is generated, wherein the second complex signal template has a π phase transition superimposed at the boundary of each frame.

[0174] It should be noted that the data link signal synchronization and rate identification device provided in the embodiments of the present invention can realize all the method steps implemented in the above-mentioned data link signal synchronization and rate identification method embodiments, and can achieve the same technical effect. Here, the parts and beneficial effects that are the same as those in the method embodiments will not be described in detail.

[0175] Figure 10 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 10As shown, the electronic device may include: a processor 1010, a communications interface 1020, a memory 1030, and a communications bus 1040, wherein the processor 1010, the communications interface 1020, and the memory 1030 communicate with each other through the communications bus 1040. The processor 1010 can call logic instructions in the memory 1030 to execute a data link signal synchronization and rate identification method. This method includes: acquiring the complex baseband signal of the data link signal; generating a first complex signal template and a second complex signal template corresponding to a first frame length and a second frame length, respectively, wherein both the first and second complex signal templates contain a carrier with a frequency of a synchronization tone and have a phase transition at each frame boundary; performing sliding correlation processing on the complex baseband signal with the first and second complex signal templates respectively, and normalizing the correlation results to obtain a first normalized correlation curve and a second normalized correlation curve; performing peak search on the first and second normalized correlation curves respectively, and performing cross-curve matching based on the acquired candidate peak position set to determine a burst synchronization point; comparing the peak scores of the first and second normalized correlation curves at the burst synchronization point, and determining a burst rate mode based on the comparison results.

[0176] Furthermore, the logical instructions in the aforementioned memory 1030 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0177] On the other hand, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements a method for synchronizing and identifying data link signals provided by the methods described above. The method includes: acquiring a complex baseband signal of a data link signal; generating a first complex signal template and a second complex signal template corresponding to a first frame length and a second frame length, respectively, wherein both the first complex signal template and the second complex signal template contain a carrier with a frequency of a synchronization tone and have a phase transition at the boundary of each frame; performing sliding correlation processing on the complex baseband signal with the first complex signal template and the second complex signal template, respectively, and normalizing the correlation results to obtain a first normalized correlation curve and a second normalized correlation curve; performing peak search on the first normalized correlation curve and the second normalized correlation curve, respectively, and performing cross-curve matching based on the acquired candidate peak position set to determine a burst synchronization point; comparing the peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point, and determining a burst rate mode based on the comparison results.

[0178] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0179] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0180] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synchronizing and identifying the rate of a data link signal, characterized in that, include: Acquire the complex baseband signal of the data link signal; A first complex signal template and a second complex signal template corresponding to the first frame length and the second frame length are generated respectively. Both the first complex signal template and the second complex signal template contain a carrier with a frequency of synchronous single tone, and each frame boundary has a phase jump. The complex baseband signal is subjected to sliding correlation processing with the first complex signal template and the second complex signal template respectively, and the correlation results are normalized to obtain the first normalized correlation curve and the second normalized correlation curve. Peak search is performed on the first normalized correlation curve and the second normalized correlation curve respectively, and cross-curve matching is performed based on the obtained candidate peak position set to determine the sudden synchronization point; The peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point are compared, and the burst rate pattern is determined based on the comparison results.

2. The data link signal synchronization and rate identification method according to claim 1, characterized in that, The step of performing sliding correlation processing on the complex baseband signal with the first complex signal template and the second complex signal template respectively, and normalizing the correlation results to obtain a first normalized correlation curve and a second normalized correlation curve includes: The complex baseband signal is subjected to sliding correlation processing with the first complex signal template to obtain a first correlation value corresponding to each sliding position, and the energy of a first data segment of the complex baseband signal with a length of the first signal length is calculated at each sliding position; the first signal length is calculated based on the first frame length. Based on the squared amplitude of the first correlation value, the length of the first signal, and the energy of the first data segment, a first normalized correlation value is calculated, and a first normalized correlation curve is generated based on the first normalized correlation value. The complex baseband signal is subjected to sliding correlation processing with the second complex signal template to obtain the second correlation value corresponding to each sliding position, and the energy of the second data segment of the complex baseband signal with a length of the second signal length at each sliding position is calculated; the second signal length is calculated based on the second frame length. Based on the squared amplitude of the second correlation value, the second signal length, and the energy of the second data segment, a second normalized correlation value is calculated, and a second normalized correlation curve is generated based on the second normalized correlation value.

3. The data link signal synchronization and rate identification method according to claim 2, characterized in that, The calculation of the first normalized correlation value based on the squared amplitude of the first correlation value, the length of the first signal, and the energy of the first data segment includes: Calculate the first product of the first signal length and the energy of the first data segment, and add the first product to a preset positive number to obtain the first denominator value; The first normalized correlation value is obtained by squared the magnitude of the first correlation value and dividing it by the first denominator value.

4. The data link signal synchronization and rate identification method according to claim 1, characterized in that, The step of performing peak search on the first normalized correlation curve and the second normalized correlation curve respectively, and performing cross-curve matching based on the obtained candidate peak position set to determine the sudden synchronization point includes: The first candidate peak of the first normalized correlation curve is detected, and the first candidate peak is suppressed by minimum spacing to obtain the set of positions of the first candidate peak. The second candidate peak of the second normalized correlation curve is detected, and the second candidate peak is suppressed by minimum spacing to obtain the set of second candidate peak positions; the first candidate peak and the second candidate peak are local maxima points with amplitudes not lower than a preset threshold; If there exists a pair of candidate peaks in the first set of candidate peak positions and the second set of candidate peak positions where the position difference between the candidate peaks is less than the preset window width, then the candidate peak pair is determined to belong to the same burst, and the burst synchronization point is determined based on the position of the candidate peak pair.

5. The data link signal synchronization and rate identification method according to claim 4, characterized in that, The step of performing minimum spacing suppression on the first candidate peak to obtain the set of positions of the first candidate peak includes: Traverse the first candidate peak in chronological order; If the distance between the current candidate peak and the previous selected peak is less than a preset spacing threshold, then the peak with the larger amplitude between the current candidate peak and the previous selected peak will replace the previous selected peak in the selected peak list. If the distance between the current candidate peak and the previous selected peak is greater than or equal to a preset spacing threshold, then the current candidate peak is added to the selected peak list. The list of selected peaks at the end of the traversal is used as the set of the first candidate peak positions.

6. The method for synchronizing and identifying the data link signal according to any one of claims 1 to 5, characterized in that, The step of comparing the peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point, and determining the burst rate pattern based on the comparison results, includes: On the first normalized correlation curve and the second normalized correlation curve, a neighborhood window centered on the burst synchronization point is taken respectively, and the maximum peak value within the neighborhood window is taken as the peak score; The burst rate mode is determined based on the frame length corresponding to the normalized correlation curve with the higher peak score.

7. The method for synchronizing and identifying the rate of a data link signal according to any one of claims 1 to 5, characterized in that, The generation of the first complex signal template and the second complex signal template corresponding to the first frame length and the second frame length, respectively, includes: Based on the sampling rate, calculate the first number of samples per frame and the first signal length corresponding to the first frame length; Based on the sampling rate, calculate the second number of samples per frame and the second signal length corresponding to the second frame length; Based on the synchronous single-tone frequency and the first number of samples per frame, a first complex signal template with a length equal to the length of the first signal is generated, wherein the first complex signal template has a π phase transition superimposed at the boundary of each frame; Based on the synchronous single-tone rate and the second number of samples per frame, a second complex signal template with a length equal to the length of the second signal is generated, wherein the second complex signal template has a π phase transition superimposed at the boundary of each frame.

8. A data link signal synchronization and rate identification device, characterized in that, include: The data link signal processing module is used to acquire the complex baseband signal of the data link signal; The complex signal template generation module is used to generate a first complex signal template and a second complex signal template corresponding to the first frame length and the second frame length, respectively. Both the first complex signal template and the second complex signal template contain a carrier with a frequency of synchronous single tone, and each frame boundary has a phase jump. The sliding correlation and normalization module is used to perform sliding correlation processing on the complex baseband signal with the first complex signal template and the second complex signal template respectively, and normalize the correlation results to obtain the first normalized correlation curve and the second normalized correlation curve. The sudden synchronization point determination module is used to perform peak search on the first normalized correlation curve and the second normalized correlation curve respectively, and perform cross-curve matching based on the obtained candidate peak position set to determine the sudden synchronization point; The rate pattern determination module is used to compare the peak scores of the first normalized correlation curve and the second normalized correlation curve at the burst synchronization point, and determine the burst rate pattern based on the comparison results.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the data link signal synchronization and rate identification method as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the data link signal synchronization and rate identification method as described in any one of claims 1 to 7.

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