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Time-frequency joint synchronization method of costas sequence based on full-phase spectrum correction

A technology of all-phase spectrum and time-frequency combination, which is applied in the direction of synchronization device, synchronization error detection, frequency modulation carrier system, etc., can solve the problems of main lobe spectral line interference and error, and achieve the effect of avoiding large errors in discrete spectrum analysis

Active Publication Date: 2022-01-07
CHONGQING UNIV OF POSTS & TELECOMM
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AI Technical Summary

Problems solved by technology

If there is a time delay in the signal, the sampled signal will have a noise-only signal. In this case, using a window function whose length is a single symbol time for the short-time Fourier transform will result in a part of the current symbol The information exists in the next symbol time. In the MFSK signal, when the frequency interval between two symbols is small, due to the influence of spectrum leakage, it will cause serious interference to the main lobe spectral line used by the discrete spectrum analysis algorithm. cause large error
[0006] In summary, although the time-frequency joint synchronization algorithm for shortwave MFSK communication based on Costas sequences has high estimation accuracy, there is still room for improvement. The improvement of the spectrum correction algorithm will further improve the synchronization accuracy of the algorithm

Method used

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  • Time-frequency joint synchronization method of costas sequence based on full-phase spectrum correction
  • Time-frequency joint synchronization method of costas sequence based on full-phase spectrum correction
  • Time-frequency joint synchronization method of costas sequence based on full-phase spectrum correction

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Embodiment 1

[0033] This embodiment provides a Costas sequence time-frequency joint synchronization method based on full-phase spectrum correction, such as Figure 1-2 Shown, in a preferred embodiment, it comprises the following steps:

[0034] Step S1, after receiving the time-domain signal x(N), the receiving end divides the time-domain signal x(N) according to the symbol time, and changes the time-domain signal x(N) into m times representing symbol information Domain signal, get the split signal as x 1 (n), x 2 (n)...x m (n), referred to as the split signal x i (n), where i=1, 2, ..., m, m represents the number of divided signals.

[0035] Step S2, put x i (n) Carry out inversion transform and add window to perform all-phase Fourier transform, and obtain the split signal x after completing the apFFT process i The all-phase Fourier transform of (n) X 1 (W)--X m (W), perform modulus calculation to obtain the segmentation signal x i Spectrum of (n)|X1 (W)| 2 --|X m (W)| 2 , use...

Embodiment 2

[0050] In this embodiment, it is assumed that the symbol time is T, the sampling rate is fs, the time-domain signal frequency offset is f, and the time delay is τ.

[0051] A Costas sequence time-frequency joint synchronization method based on all-phase spectrum correction, including but not limited to the following steps:

[0052] (1), the time domain signal is divided according to the symbol time T, and the divided signal is x 1 (n), x 2 (n)...x m (n). Due to the influence of time delay, part of the information of the previous symbol will exist in the next segmented signal. with x 2 (n) as an example, if there is no time delay, then x 2 (n) represents the time-domain waveform of the second symbol symbol, at this time x 2 (n) is:

[0053] x 2 (n)=A 2 sin[2πf 2 (n-τ)] (1)

[0054] Among them, A 1 Indicates the signal amplitude within the first symbol time, A 2 Indicates the signal amplitude within the second symbol time, n is the time discrete representation, τ i...

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Abstract

The invention relates to the field of digital signal processing, in particular to a Costas sequence time-frequency joint synchronization method based on all-phase spectrum correction, which improves the problems existing in the discrete spectrum correction algorithm using short-time Fourier transform and sliding correlation , the improvement mainly includes: the present invention proposes a solution based on iterative optimization, when the actual frequency offset is an integer multiple of the spectral resolution, a larger error will occur, and the present invention uses an estimated value with a larger estimated error Perform frequency offset correction and time delay correction on the signal, and then estimate again, so that the frequency offset of the signal is not a special value through an iterative method. For the second problem, due to the error caused by the spectrum leakage, the present invention uses the all-phase Fourier transform instead of the FFT in the short-time Fourier transform to reduce the spectrum leakage phenomenon as much as possible. By improving the above two points, the estimation accuracy of the original algorithm is improved.

Description

technical field [0001] The invention relates to the field of digital signal processing, in particular to a Costas sequence time-frequency joint synchronization method based on all-phase spectrum correction. Background technique [0002] Shortwave MFSK communication is widely used in application scenarios with low rate and minimum guarantee. For a communication system, the premise of receiving a signal is to detect the signal and realize the synchronization of the transmitting and receiving ends. The quality of the synchronization performance directly affects the performance of the communication system. Synchronization errors or loss of synchronization can result in degraded communication system performance or loss of communication. [0003] In the short-wave MFSK communication system, the commonly used signal synchronization method is a data-assisted synchronization algorithm. The data-assisted synchronization algorithm is completed by inserting the training sequence in th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/10H04L27/00H04L7/00
CPCH04L27/106H04L27/0014H04L7/0054H04L2027/0026H04L7/007Y02D30/70
Inventor 李景慧李国军叶昌荣马欢郑广发罗一平王尊立
Owner CHONGQING UNIV OF POSTS & TELECOMM
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