Synchronous demodulation method and device for digital communication signal

Abstract

The present invention proposes a digital communication signal synchronous demodulation method and its device, which relate to the field of wireless transmission technology. The intermediate frequency digital signal is observed through a fixed-length sliding window, and the reconstructed carrier frequency domain signal and frequency are obtained through a compressed sensing algorithm. information; according to the reconstructed carrier frequency domain signal and frequency information, the residual Doppler frequency offset signal and modulation signal are obtained through the numerical control oscillator, and the residual Doppler frequency offset signal is extracted and synchronized through the low-order phase-locked loop, Obtain the baseband digital signal; and correct the phase deviation of the baseband digital signal and detect and judge through intelligent learning. The invention can be applied to high-speed and high-dynamic scenes, and has many significant advantages such as high signal-to-noise ratio, low bit error rate, high robustness and high real-time performance.

Description

technical field [0001] The invention relates to the technical field of wireless transmission, in particular to a digital communication signal synchronous demodulation method and a device thereof. Background technique [0002] In the wireless transmission system, for the reception of digitally modulated signals with carrier modulation, an orthogonal modulator is generally used to carry out carrier coherent demodulation and extract intermediate frequency digital signals. However, due to the time-varying effect of multipath in the actual transmission process, the transmitter and receiver cannot generate ideal and accurate synchronous carriers; the Doppler frequency shift introduced due to relative motion makes it inevitable that there will be frequency deviation in the intermediate frequency digital signal And phase deviation, resulting in the inability to achieve complete carrier demodulation. In particular, in high-speed and high-dynamic scenes, high acceleration and jerk of...

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Problems solved by technology

[0005] 1) The traditional differential demodulation method only uses the time information of adjacent symbols to judge the baseband digital signal, resulting in limited demodulation performance;

[0006] 2) In order to adapt to the high dynamic range of Doppler, it is necessary to increase the loop bandwidth and increase the order of the phase-locked loop; however, increasing the loop bandwidth will increase the high noise entering the phase-locked loop to a certain extent, thereby deteriorating the transmission In addition, increasing the order of the phase-locked loop can eliminate the steady-state error caused by the high dynamic range of Doppler, but at the same time it will lead to the introduction of noise and the increase of system computational complexity, which will affect the high-speed and high-speed Real-time performance of dynamic communication transmission system;

[0008] 4) In the multipath time-varying environment, the channel coefficient changes rapidly, which makes it impossible to use pilot information or based on known prior information to perform optimal unbiased estimation and compensation, and it will affect the demodulation process of the receiving end to a certain extent. Judgment on symbols, which in turn affects the bit error rate of system transmission

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