A Phase Tracking Method for LEO Satellite Mapsk Communication System

Abstract

The invention relates to the technical field of high-order APSK carrier synchronization, in particular to a phase tracking method for a low-orbit satellite MAPSK communication system; two phase detectors are used, and a loop filter with variable parameters is introduced to divide the process of carrier recovery Coarse synchronization and fine synchronization; firstly, the amplitude judgment is made on the MAPSK modulated signal, and the four constellation points with high SNR on the outer circle are used to perform coarse synchronization using the polarity judgment algorithm of the simplified constellation. At this time, the bandwidth of the loop filter is relatively small If the state controller detects the loop phase error and finds that the loop filter is already in the locked state, it means that the coarse synchronization is completed, then switch the carrier recovery circuit to fine synchronization, and use the decision guidance The algorithm performs phase detection on all constellation points. At this time, the loop filter achieves the purpose of stable tracking through the mode of small bandwidth, thus effectively improving the performance of the high-order APSK communication system of low-orbit satellites.

Description

A Phase Tracking Method for Low-orbit Satellite MAPSK Communication System technical field The present invention relates to high-order APSK carrier synchronization technology field, be specifically related to a kind of low-orbit satellite MAPSK communication system phase tracking method. Background technique With the development of satellite communication, spectrum resources are becoming more and more tense, and the demand for data transmission is increasing sharply. For satellite communication, high-speed data transmission must be achieved within a limited bandwidth, so it is necessary to use high-bandwidth efficient high-order Modulation. The satellite channel is a typical nonlinear channel. Compared with the low-order modulation, the high-order modulation signal will face more serious problems. Signal distortion. The traditional QAM modulation constellation has many amplitude levels and is therefore very sensitive to channel nonlinearity; while the concentric ci...

AI Technical Summary

Problems solved by technology

However, these high-order APSK modulation signals are more seriously affected by the carrier frequency difference, and because there are multiple amplitudes in the high-order APSK modulation constellation, the minimum phase difference between signal points is smaller, and the phase discrimination becomes narrower, limiting The phase detection range of the phase detector is limited, so that the conventional full-constellation phase detector cannot work under a large frequency offset

Images