Method for estimating carrier frequency of PSK (phase shift keying) signal in Alpha-stable distribution noise

Abstract

Disclosed is a method for estimating carrier frequency of a PSK (phase shift keying) signal in Alpha-stable distribution noise. The method includes: valuing a cyclic covariance function of the received PSK signal with the Alpha-stable distribution noise; valuing a cyclic covariance spectrum by subjecting the cyclic covariance function to Fourier transform; extracting a section with cyclic frequency being epsilon=0Hz according to the obtained cyclic covariance spectrum; searching peak values of a positive semi-axis and a negative semi-axis of the section respectively to find a positive frequency value and a negative frequency value corresponding to the peak values, and valuing a mean value as the estimated value of the carrier frequency after absolute values are valued. The method is capable of estimating the carrier frequency of the PSK signal in the Alpha-stable distribution noise and is good in estimating performance in an environment of low signal to noise ratio.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to a method for estimating the symbol rate of a PSK signal under Alpha stable distributed noise. Background technique [0002] As an important part of the communication field, satellite communication occupies an important position in both civil and military fields. Understanding and mastering the distribution and parameters of satellite signals in specific frequency bands (such as signal carrier frequency, symbol rate, bandwidth, etc.) It is of great significance to intercept, analyze and decipher information. However, due to the complex and changeable noise environment of space communication and the increasingly serious interference problem, the signal is easily affected by it and presents a weak state. Therefore, improving the detection and parameter estimation of weak signals under low SNR conditions in deep space communication is an urgent problem to be solved...

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Problems solved by technology

However, this literature does not give specific algorithm steps for carrier frequency estimation, and further research on its covariance spectrum is still needed to estimate the carrier frequency (Sun Yongmei, Qiu Tianshuang, Li Hui, Wei Mei. Spectrum analysis method for α-stable distribution process [J].Journal of Dalian Jiaotong University,2010,31(4):9-12)

Aiming at the problem that the parameter estimation method based on second-order cyclic statistics is severely degraded in Alpha stable distributed noise, Zhao Chunhui et al. proposed a method for estimating the carrier frequency of MPSK signals based on fractional low-order cyclic spectrum. For different M values For PSK signals, the relationship between the carrier frequency and the corresponding fractional low-order cyclic spectrum parameters is analyzed, and on this basis, a carrier frequency estimation method suitable for all PSK signals is given

In this method, when the mixed signal-to-noise ratio is -10dB and α is 1.5, the normalized mean square error of carrier frequency estimation of BPSK signal is 0.043, and the normalized mean square error of carrier frequency estimation of QPSK signal is 0.041, so the low signal The performance of carrier frequency estimation under noise ratio still needs to be improved (Zhao Chunhui, Yang Weichao, Cheng Baozhi. MPSK signal parameter estimation under the background of Alpha stable distribution noise[J]. Journal of Shenyang University of Technology, 2013,35(2):194-199 )

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