Low-orbit constellation system terminal carrier synchronization method and carrier synchronization demodulation device

Abstract

The invention discloses a low-orbit constellation system terminal carrier synchronization method and a carrier synchronization demodulation device, and belongs to the field of satellite communication. The carrier synchronization method comprises the following steps that: a terminal carries out low-pass filtering and data downsampling on a downlink time domain signal and then carries out time domain primary synchronization signal PSS quick capture to complete coarse estimation of timing and frequency of the time domain signal; the terminal sends coarse timing and frequency estimation information to a timing adjustment module and a digital down-conversion module to complete timing adjustment and frequency compensation respectively; carrying out FFT (Fast Fourier Transform) processing on the time domain data after coarse synchronization, and finishing conversion from a time domain signal to a frequency domain signal; and sending the frequency domain data to a fine timing synchronization module to complete coarse timing synchronization estimation and fine timing synchronization estimation, performing compensation processing on the frequency domain data by using fine timing estimation information, performing de-spreading processing on the frequency domain data, and sending the de-spread reference signal to a frequency estimation module to complete carrier fine frequency estimation.

Description

technical field [0001] The invention belongs to the technical field of satellite mobile communication, in particular to a terminal carrier timing and frequency synchronization method in a low-SNR environment of a low-orbit satellite constellation system. Background technique [0002] In the satellite mobile communication system, TDMA\FDMA technical system is usually adopted. Among them, the FDMA (Frequency Division Multiple Address, Frequency Division Multiple Access) system uses the uplink and downlink spectrum resources completely independently, and the TDMA (Time Division Multiple Address, Time Division Multiple Access) system frame structure consists of hyperframe, superframe, multiframe, frame and In the low-orbit constellation system, due to the rapid change of the relative position between the satellite and the ground terminal, the timing drift and the large Doppler frequency shift are characteristic, and the global operation of the low-orbit constellation passes thro...

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Problems solved by technology

[0003] At present, the timing and frequency tracking methods in low-orbit constellations in the prior art have not been introduced in detail in the low-orbit satellite scenario for the OFDM combined with CDMA technology system with high spectral efficiency, and the existing low-orbit systems are mainly focused on CDMA. Domain spread spectrum and TDMA / FDMA-related transmission technology research, and there is no commercial miniaturization design for ground mobile communication terminals related to low-orbit constellations. Most of them are experimental test equipment, and related timing estimation and frequency drift depend on high stability and accuracy. The hardware clock scheme design of

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