A frame synchronization acquisition method and system for multi-tone parallel modulation system waveforms

Abstract

The application discloses a frame synchronization capture method and system for multi-tone parallel modulation system waveforms, and belongs to the field of digital signal processing. The method adopts three kinds of joint information of sliding time window and frequency, amplitude and phase correlation degree to make a synchronization capture decision, that is, when making the synchronization capture decision, the frequency, amplitude and phase information is used to calculate the correlation of the sampling sequence and the synchronization head respectively and weighted calculation is performed to obtain the synchronization correlation degree, so that the frame synchronization capture deviation is reduced. Compared with the prior art which uses all sample points of the overall synchronization head for calculation, the application extracts corresponding frequency points according to the waveform system in sections, so that the calculation amount is reduced, the calculation efficiency is improved, the sample points input in the current time slot are ensured to be processed in the current time slot without accumulation, and the processing delay is reduced.

Description

Technical Field

[0001] This invention belongs to the field of digital signal processing, and more specifically, relates to a frame synchronization acquisition method and system for multi-tone parallel modulation waveforms. Background Technology

[0002] Shortwave communication, with its strong resistance to disruption, high flexibility, simple equipment, and low cost, has become a primary means of medium- and long-distance communication in countries worldwide. However, in real-time shortwave communication, due to the time-varying characteristics of the shortwave channel, the transmission time, time slot allocation, and channel delay are all unknown. To ensure real-time reception of communication signals and to allow sufficient response time for subsequent signal demodulation and decoding, fast and high-precision frame synchronization acquisition is crucial, as it significantly impacts the performance of subsequent channel parameter estimation.

[0003] Existing waveform synchronization techniques, prioritizing communication reliability and channel estimation accuracy, typically employ long synchronization headers for acquisition, while also considering interpolation probe sequences. However, using long synchronization header sequences can introduce drawbacks in practical engineering applications, including latency while waiting to receive the header sequence and increased computational load due to processing more sampling points. These drawbacks can affect the processing response speed of the receiving end, reducing the time margin reserved for processing the bit information carried by the communication signal. Furthermore, for waveforms in multi-tone parallel modulation systems that require high waveform processing speed, the phase difference steps between sample points are usually small, potentially leading to significant deviations when using conventional frame synchronization acquisition methods. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a frame synchronization acquisition method and system for multi-tone parallel modulation waveforms, thereby solving the problems of large signal processing delays and difficulty in reserving more processing response time for subsequent signal processing in existing waveform frame synchronization acquisition methods when processing multi-tone parallel modulation waveform signals.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a frame synchronization acquisition method for waveforms in a multi-tone parallel modulation system. This method is applied at a receiving end and includes:

[0006] The received raw signal is preprocessed to obtain the IQ complex signal;

[0007] Slide a time window to sample the IQ complex signal to obtain a sampled symbol sequence of the same length as the synchronization header;

[0008] The current sampled symbol sequence is divided into multiple segments containing the number of sample points of a single modulation symbol;

[0009] Performing DFT transformation on each segmented result, determining a frequency estimation value according to the DFT transformation result, and calculating the normalized frequency correlation degree of the segment and the peak position index corresponding to the single tone by combining the standard frequency and the channel width;

[0010] Determining an energy amplitude value and an initial IQ phase respectively according to the peak position index corresponding to the single tone, and calculating the normalized correlation degree of the index corresponding to the segment by combining the single tone corresponding index value specified by the waveform system;

[0011] Calculating the normalized correlation degree of the overall index corresponding to the current sampled symbol sequence according to the normalized correlation degrees of the same index of all segments;

[0012] Weighting the normalized correlation degrees of three indexes of the overall sampled symbol sequence to obtain the synchronous correlation degree of the current sampled symbol sequence; if the synchronous correlation degree is greater than a frame synchronization criterion, taking the starting position of a current sliding time window as a frame synchronization position; otherwise, updating the current sampled symbol sequence to a next sampled symbol sequence obtained by sliding sampling, and jumping back to the above segmentation operation until sampling is completed.

[0013] Preferably, performing preprocessing on the received original signal to obtain an IQ complex signal specifically comprises:

[0014] when the original signal is a radio frequency signal, converting the original signal into an intermediate frequency signal after removing a high-frequency carrier, then performing A / D sampling on the intermediate frequency signal to obtain a discrete-time real signal, and obtaining a discrete-time IQ complex signal through a Hilbert filter;

[0015] when the original signal is an intermediate frequency signal, directly performing A / D sampling on the original signal to obtain a discrete-time real signal, and obtaining a discrete-time IQ complex signal through a Hilbert filter.

[0016] Preferably, performing DFT transformation on each segmented result and determining a frequency estimation value according to the DFT transformation result specifically comprises:

[0017] For the i-th segment r i , N-point DFT transformation is performed, the number of DFT transformation points N is not less than the number of samples of a single modulation symbol, zero padding is performed on r i when the number of points is insufficient, and the transformation result of the i-th segment is expressed as a sequence of length N

[0018] According to the DFT transformation result R i [N], performing numerical comparison near the DFT index position corresponding to the standard value f s of the single-tone frequency to obtain the peak value, thereby determining each single-tone frequency estimation value f s ′ in the i-th segment of the synchronization header, where 0≤s<S, and S is the number of single-tone frequencies included in each multi-tone modulation symbol.

[0019] Preferably, the normalized frequency correlation of the segment is calculated by combining the standard frequency and the waveguide width, specifically as follows:

[0020] Calculate the frequency difference Δf of each note. s =f s -f s ′,0≤s <S;

[0021] Using Δf s Calculate the normalized frequency correlation corr of the i-th segment of the current sampling sequence, using the channel width Δf. f (i):

[0022]

[0023] Among them, f s ′ represents the estimated frequency of each monotone in the i-th segment of the synchronization header, f s S represents the standard value of each single-tone frequency in the i-th segment of the synchronization header, and S represents the number of single-tone frequencies contained in each multi-tone modulation symbol.

[0024] Preferably, the step of determining the energy amplitude value and the initial IQ phase based on the peak position index corresponding to the single tone specifically involves:

[0025] According to the i-th segment r of the synchronization header i Peak position index l = N*f for each monotone s ′ / f s Calculate the energy amplitude value Y corresponding to each single audio point. s ′:

[0026]

[0027] Calculate the initial IQ phase corresponding to each single audio point.

[0028]

[0029] Where N is the number of DFT transform points, f s ′ represents the estimated frequency of each monotone in the i-th segment of the synchronization header, f s S represents the standard value of each single-tone frequency in the i-th segment of the synchronization header, and S represents the number of single-tone frequencies contained in each multi-tone modulation symbol.

[0030] Preferably, the normalized correlation of the segment-corresponding index value is calculated based on the single-tone corresponding index value specified by the resynthetic waveform system, specifically as follows:

[0031] Calculate the normalized magnitude correlation of the i-th segment of the current sampled sequence.

[0032] Calculate the normalized phase correlation of the i-th segment of the current sampled sequence.

[0033] Among them, Y s ′ represents the energy amplitude value corresponding to each single audio point. Let S be the initial IQ phase corresponding to each single-tone point, S be the number of single-tone frequencies contained in each multi-tone modulation symbol, and Y be... s , These are the amplitude corresponding to a single tone and the initial IQ phase, as specified by the waveform system.

[0034] Preferably, the step of calculating the normalized correlation of the overall corresponding index of the current sampled symbol sequence based on the normalized correlation of all segments with the same index specifically involves:

[0035] Calculate the overall normalized frequency correlation of the current sampled sequence.

[0036] Calculate the overall normalized magnitude correlation of the current sampled sequence.

[0037] Calculate the overall normalized phase correlation of the current sampled sequence.

[0038] Among them, corr f (i), corr a (i) These are the normalized frequency correlation, energy correlation, and phase correlation of the i-th segment, respectively, L N The number of segments.

[0039] Preferably, the normalized correlation of the three indicators of the weighted sampled symbol sequence is used to obtain the synchronization correlation (corr) of the current sampled symbol sequence, specifically:

[0040]

[0041] Where, α f ,α a , These are respectively represented as normalized frequency correlation coefficients (corr). f Normalized magnitude correlation (corr) a and normalized phase correlation The weighting coefficients are assigned, and the values ​​of the three weighting coefficients are related to the waveform modulation scheme.

[0042] Preferably, if the synchronization header and the false alarm probability are the same, the frame synchronization criteria are the same; otherwise, the frame synchronization criteria are different.

[0043] To achieve the above objectives, in a second aspect, the present invention provides a frame synchronization acquisition system for multi-tone parallel modulation waveforms, comprising: a processor and a memory; the memory for storing computer execution instructions; and the processor for executing the computer execution instructions, such that the method described in the first aspect is executed.

[0044] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0045] This invention provides a frame synchronization acquisition method and system for multi-tone parallel modulation waveforms. It employs a sliding time window combined with three types of information—frequency, amplitude, and phase correlation—for synchronization acquisition decisions. Specifically, during the synchronization acquisition decision process, the correlation between the sampled sequence and the synchronization header is calculated using frequency, amplitude, and phase information respectively, and then weighted to obtain the synchronization correlation, thereby reducing frame synchronization acquisition deviation. Compared to existing technologies that use all sample points of the entire synchronization header for calculation, this invention uses segmentation and extracts corresponding frequency points according to the waveform mode, thus reducing the computational load and improving computational efficiency. It also ensures that sample points input in the current time slot are processed within the current time slot without accumulation, thereby reducing processing latency. Attached Figure Description

[0046] Figure 1 The present invention provides a flowchart of a frame synchronization acquisition method for waveforms of a multi-tone parallel modulation system. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0048] like Figure 1 As shown, this invention provides a frame synchronization acquisition method for multi-tone parallel modulation waveforms. This method is applied at the receiving end and includes:

[0049] The received raw signal is preprocessed to obtain the IQ complex signal;

[0050] Slide a time window to sample the IQ complex signal to obtain a sampled symbol sequence of the same length as the synchronization header;

[0051] The current sampled symbol sequence is divided into multiple segments containing the number of sample points of a single modulation symbol;

[0052] Perform DFT transformation on the results of each segment, determine the frequency estimate based on the DFT transformation results, and calculate the normalized frequency correlation and peak position index of the single tone for the segment by combining the standard frequency and the channel width.

[0053] Determining the energy amplitude value and the initial IQ phase respectively according to the peak position index corresponding to each single tone, and then calculating the normalized correlation degree of the corresponding index of the segment by combining the single tone corresponding index value specified by the waveform system;

[0054] Calculating the normalized correlation degree of the overall corresponding index of the current sampled symbol sequence according to the normalized correlation degrees of the same index of all segments;

[0055] Obtaining the synchronous correlation degree of the current sampled symbol sequence by weighting the normalized correlation degrees of three overall indexes of the sampled symbol sequence, if the synchronous correlation degree is greater than the frame synchronization criterion, taking the starting position of the current sliding time window as the frame synchronization position, otherwise, updating the current sampled symbol sequence to the next sampled symbol sequence obtained by sliding sampling and jumping back to the above-mentioned segmentation operation until the sampling is completed.

[0056] Preferably, preprocessing the received original signal to obtain an IQ complex signal specifically comprises:

[0057] when the original signal is a radio frequency signal, converting the original signal into an intermediate frequency signal after removing the high-frequency carrier, then performing A / D sampling on the intermediate frequency signal to obtain a discrete-time real signal, and obtaining a discrete-time IQ complex signal through a Hilbert filter;

[0058] when the original signal is an intermediate frequency signal, directly performing A / D sampling on the original signal to obtain a discrete-time real signal, and obtaining a discrete-time IQ complex signal through a Hilbert filter.

[0059] Preferably, performing DFT transformation on each segment result and determining a frequency estimation value according to the DFT transformation result specifically comprises:

[0060] performing N-point DFT transformation on the i-th segment t i wherein the number of DFT transformation points N is not less than the number of samples of a single modulation symbol, and zero-padding is performed on r i when the number of points is insufficient, the transformation result of the i-th segment is represented as a sequence with a length of N

[0061] according to the DFT transformation result R i [N], performing numerical comparison near the DFT index position corresponding to the standard value f s of the single tone frequency to obtain the peak value, so as to determine the estimated value f s ′ of each single tone frequency in the i-th segment of the synchronization header, 0≤s<S, wherein S is the number of single tone frequencies included in each multi-tone modulation symbol.

[0062] It is known that the symbol interval of the communication system is T, and the sampling interval is T s , and the signal sequence processed by the receiving end is y(kT S )=[y0,y1,...yL-1 , wherein k is a non-negative integer. The multi-tone parallel modulation signal system of a communication system stipulates that each multi-tone modulation symbol of a synchronization header includes S single-tone frequencies, and the standard value of the single-tone frequency is fs(0<s<S). A sliding time window is used to process y(kT s ) for sampling, that is, with τ u = i u T s as the starting time, sampling is performed at every interval of sampling time period T s , and the length of a sampling frame is L ( L equals the sample point length of the waveform synchronization header, L = n s L N , n s is the number of sample points contained in a single multi-tone modulation symbol, L N is the number of multi-tone modulation symbols included in the waveform synchronization header part), then the sampled symbol sequence can be expressed as:

[0063]

[0064] It is assumed that the frame synchronization calculation interval is T / (2T S ), whenever at the time k = i·T / (2T s ), the monitoring signal sampling sequence y(kT S ) is segmented according to the signal system stipulated by communication regulations. The segmentation method is to segment the signal sampling sequence y(kT s ) into L S segments according to the number of sample points of a single modulation symbol specified by the signal system (that is, n N ), and the i-th segment is denoted as r i , i = 0, 1, … L N -1.

[0065] r i = {y(kTs)}, i = 0, 1, … L N -1, k = iL N +n, n = 0, 1, … Ns

[0066] Estimation is sequentially performed by using the segmentation result r i of the sampled symbol sequence, N-point DFT transformation (n≤N) is performed on r i (since the DFT point number N is usually a power of 2, when the number of points is insufficient, zero padding is required for r s ), the transformation result of the i-th segment can be expressed as a sequence Ri[N] with a length of N. i

[0067]

[0068] ​Preferably, the normalized frequency correlation of the segment is calculated by combining the standard frequency and the waveguide width, specifically as follows:

[0069] Calculate the frequency difference Δf of each note. s =f s -f s ′,0≤s <S;

[0070] Using Δf s Calculate the normalized frequency correlation corr of the i-th segment of the current sampling sequence, using the channel width Δf. f (i):

[0071]

[0072] Among them, f s ′ represents the estimated frequency of each monotone in the i-th segment of the synchronization header, f s S represents the standard value of each single-tone frequency in the i-th segment of the synchronization header, and S represents the number of single-tone frequencies contained in each multi-tone modulation symbol.

[0073] Preferably, the step of determining the energy amplitude value and the initial IQ phase based on the peak position index corresponding to the single tone specifically involves:

[0074] According to the i-th segment r of the synchronization header i Peak position index l = N*f for each monotone s ′ / f s Calculate the energy amplitude value Y corresponding to each single audio point. s ′:

[0075]

[0076] Calculate the initial IQ phase corresponding to each single audio point.

[0077]

[0078] Where N is the number of DFT transform points, f s ′ represents the estimated frequency of each monotone in the i-th segment of the synchronization header, f s S represents the standard value of each single-tone frequency in the i-th segment of the synchronization header, and S represents the number of single-tone frequencies contained in each multi-tone modulation symbol.

[0079] Preferably, the normalized correlation of the segment-corresponding index value is calculated based on the single-tone corresponding index value specified by the resynthetic waveform system, specifically as follows:

[0080] Calculate the normalized magnitude correlation of the i-th segment of the current sampled sequence.

[0081] Calculate the normalized phase correlation of the i-th segment of the current sampled sequence.

[0082] Among them, Y s ′ represents the energy amplitude value corresponding to each single audio point. Let S be the initial IQ phase corresponding to each single-tone point, S be the number of single-tone frequencies contained in each multi-tone modulation symbol, and Y be... s , These are the amplitude corresponding to a single tone and the initial IQ phase, as specified by the waveform system.

[0083] Preferably, the step of calculating the normalized correlation of the overall index corresponding to the current sampled symbol sequence based on the normalized correlation of all segments with the same index specifically involves:

[0084] Calculate the overall normalized frequency correlation of the current sampled sequence.

[0085] Calculate the overall normalized magnitude correlation of the current sampled sequence.

[0086] Calculate the overall normalized phase correlation of the current sampled sequence.

[0087] Among them, corr f (i), corr a (i) These are the normalized frequency correlation, energy correlation, and phase correlation of the i-th segment, respectively, L N The number of segments.

[0088] Preferably, the normalized correlation of the three indicators of the weighted sampled symbol sequence is used to obtain the synchronization correlation (corr) of the current sampled symbol sequence, specifically:

[0089]

[0090] Where, α f ,α a , These are respectively represented as normalized frequency correlation coefficients (corr). f Normalized magnitude correlation (corr) a and normalized phase correlation The weighting coefficients are assigned, and the values ​​of the three weighting coefficients are related to the waveform modulation scheme.

[0091] The frame synchronization decision threshold is determined in advance based on the length of the synchronization header sequence symbol of the waveform, using the Newman-Pearson criterion and simulation method. Specifically:

[0092] 1) Based on the known length of the synchronization header sequence, determine the synchronization decision threshold λ using simulation. TH The band-limited white Gaussian noise signal is used as the receiver input, where the bandwidth of the white Gaussian noise signal is equal to the bandwidth of the burst signal, and the effective value of the noise signal is equal to that of the burst signal. Typically, the duration of the noise signal sample is 700,000 seconds (approximately 8 days), but this duration can be increased when the communication system has higher false alarm probability requirements.

[0093] 2) The input signal after passing through the matched filter is denoted as y(kT) s Using a sliding time window, y(kT) s Sampling is performed, where the starting time of the sliding time window increases with each sample point, i.e., τ u =i u T s i u =0,1,2,....700000 / T s -1, sampling is performed every symbol time period T, and the sampling frame length is L. x Using sampling symbol sequences The likelihood function was calculated using the corresponding synchronization header IQ sequence x, yielding a total of 700000 / T. s The likelihood function value.

[0094] Due to the synchronization threshold λ TH The determination of the likelihood function is related to the length of the synchronization sequence, the frame synchronization algorithm, and the false alarm probability. Therefore, the same likelihood function calculation method as in actual communication should be used in the simulation. The matched filter should use the same order and filter coefficients as in the actual communication signal processing flow.

[0095] 3) Statistically analyze the likelihood function values ​​and calculate the false alarm probability P. fa =10 -7 10 -8 10 -9 The corresponding λ TH The value should be selected according to actual communication needs.

[0096] Preferably, if the synchronization header and the false alarm probability are the same, the frame synchronization criteria are the same; otherwise, the frame synchronization criteria are different.

[0097] Furthermore, based on the estimation results of the signal delay in the frame synchronization stage determined by the above method, the search interval for the next symbol timing synchronization is determined.

[0098] (1) Based on the frame synchronization position determined by the above method, determine the starting position of the search interval for the next symbol timing synchronization.

[0099] Since the frame synchronization calculation interval is T / (2T)S That is, the resolution of frame synchronization is the frame synchronization calculation interval T / (2T). S Therefore, the starting sampling point position of the symbol timing synchronization search interval can be determined as iT / (2T). S ).

[0100] (2) Determine the overall length of the search interval based on the frame synchronization position determined by the above method and the specific communication requirements, so as to obtain the end position of the search interval for the next symbol timing synchronization.

[0101] The communication requirements involved include channel conditions and processing speed requirements. Among these, the communication channel conditions determine the minimum overall length of the search interval and the maximum multipath delay D of the communication service channel. max After clarification, it can be determined that the length of the search interval is greater than [D]. max / T]·T / T s There are 16 sampling points, where [] indicates rounding up; the processing speed requirement determines the maximum value of the overall length of the search interval, which is usually no more than 16 symbols long.

[0102] (3) In actual engineering applications, the overall length of the search interval can be taken as 8 symbol lengths, and the corresponding symbol timing synchronization sampling point search interval is:

[0103] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A frame synchronization acquisition method for waveforms in a multi-tone parallel modulation system, characterized in that, This method is applied at the receiving end and includes: The received raw signal is preprocessed to obtain the IQ complex signal; Slide a time window to sample the IQ complex signal to obtain a sampled symbol sequence of the same length as the synchronization header; The current sampled symbol sequence is divided into multiple segments containing the number of sample points of a single modulation symbol; Perform DFT transformation on the results of each segment, determine the frequency estimate based on the DFT transformation results, and calculate the normalized frequency correlation and peak position index of the single tone for the segment by combining the standard frequency and the channel width. Based on the peak position index corresponding to a single tone, the energy amplitude value and the initial IQ phase are determined respectively. Then, by combining the single tone corresponding index value specified by the waveform system, the normalized correlation of the corresponding index of this segment is calculated. Based on the normalized correlation of the same indicators in all segments, calculate the normalized correlation of the overall indicators corresponding to the current sampled symbol sequence; The normalized correlation of the three indicators of the weighted sampling symbol sequence is used to obtain the synchronization correlation of the current sampling symbol sequence. If it is greater than the frame synchronization criterion, the starting position of the current sliding time window is taken as the frame synchronization position. Otherwise, the current sampling symbol sequence is updated to the next sampling symbol sequence of the sliding sampling, and the above segmentation operation is repeated until the sampling ends.

2. The method as described in claim 1, characterized in that, The preprocessing of the received raw signal yields an IQ complex signal, specifically: When the original signal is a radio frequency signal, the high-frequency carrier is removed from the original signal and it is converted into an intermediate frequency signal. The intermediate frequency signal is then sampled by an A / D converter to obtain a discrete-time real signal. The discrete-time IQ complex signal is then obtained by passing it through a Hilbert filter. When the original signal is an intermediate frequency signal, the original signal is directly sampled by an A / D converter to obtain a discrete-time real signal, which is then passed through a Hilbert filter to obtain a discrete-time IQ complex signal.

3. The method as described in claim 1, characterized in that, The process of performing a DFT transform on each segmented result and determining the frequency estimate based on the DFT transform result is as follows: For the i-th segment r i Perform an N-point DFT transform, where the number of DFT transform points N is not less than the number of points in a single modulation symbol sample. When the number of points is insufficient, adjust r accordingly. i After zero-padding, the transformation result of the i-th segment is represented as a sequence of length N. According to the DFT transform result R i [N], at the standard value f of the single-tone frequency s perform numerical comparison near the corresponding DFT index position to obtain its peak value, then the estimated value f of each single-tone frequency in the i-th segment of the synchronization header can be determined s ′, 0≤s<S, where S is the number of single-tone frequencies comprised in each multi-tone modulation symbol.

4. The method as described in claim 1, characterized in that, The normalized frequency correlation of this segment is calculated based on the combined standard frequency and waveguide width, specifically as follows: Calculate the frequency difference Δf of each note. s =f s -f s ′,0≤s <S; Using Δf s Calculate the normalized frequency correlation corr of the i-th segment of the current sampling sequence, using the channel width Δf. f (i): Among them, f s ′ represents the estimated frequency of each monotone in the i-th segment of the synchronization header, f s S represents the standard value of each single-tone frequency in the i-th segment of the synchronization header, and S represents the number of single-tone frequencies contained in each multi-tone modulation symbol.

5. The method as described in claim 1, characterized in that, The energy amplitude value and initial IQ phase are determined based on the peak position index corresponding to the single tone, specifically as follows: According to the i-th segment r of the synchronization header i Peak position index l = N*f for each monotone s ′ / f s Calculate the energy amplitude value Y corresponding to each single audio point. s ′: Calculate the initial IQ phase corresponding to each single audio point. Where N is the number of DFT transform points, f s ′ represents the estimated frequency of each monotone in the i-th segment of the synchronization header, f s S represents the standard value of each single-tone frequency in the i-th segment of the synchronization header, and S represents the number of single-tone frequencies contained in each multi-tone modulation symbol.

6. The method as described in claim 1, characterized in that, The normalized correlation of the segment-corresponding index value specified by the resynthesized waveform system is calculated as follows: Calculate the normalized magnitude correlation of the i-th segment of the current sampled sequence. Calculate the normalized phase correlation of the i-th segment of the current sampled sequence. Among them, Y s ′ represents the energy amplitude value corresponding to each single audio point. Let S be the initial IQ phase corresponding to each single-tone point, S be the number of single-tone frequencies contained in each multi-tone modulation symbol, and Y be... s , These are the amplitude corresponding to a single tone and the initial IQ phase, as specified by the waveform system.

7. The method as described in claim 1, characterized in that, The step of calculating the normalized correlation of the overall index corresponding to the current sampled symbol sequence based on the normalized correlation of all segments with the same index is as follows: Calculate the overall normalized frequency correlation of the current sampled sequence. Calculate the overall normalized magnitude correlation of the current sampled sequence. Calculate the overall normalized phase correlation of the current sampled sequence. Among them, corr f (i), corr a (i) These are the normalized frequency correlation, energy correlation, and phase correlation of the i-th segment, respectively, L N The number of segments.

8. The method as described in claim 1, characterized in that, The normalized correlation of the three indicators of the weighted sampled symbol sequence is used to obtain the synchronization correlation (corr) of the current sampled symbol sequence, specifically: Where, α f ,α a , These are respectively represented as normalized frequency correlation coefficients (corr). f Normalized magnitude correlation (corr) a and normalized phase correlation The weighting coefficients are assigned, and the values ​​of the three weighting coefficients are related to the waveform modulation scheme.

9. The method as described in claim 1, characterized in that, If the synchronization header and false alarm probability are the same, the frame synchronization criteria are the same; otherwise, the frame synchronization criteria are different.

10. A frame synchronization acquisition system for multi-tone parallel modulation waveforms, characterized in that, include: Processor and memory; The memory is used to store computer-executed instructions; The processor is configured to execute the computer execution instructions, causing the method described in any one of claims 1 to 9 to be executed.

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