A Frequency Offset Estimation Algorithm for Inter-Satellite Coherent Laser Communication
The carrier frequency offset estimation algorithm is an important component of the demodulation algorithm for inter-satellite coherent laser communication systems.The algorithm performance directly determines the accuracy of subsequent judgments and plays a crucial role in the communication performance of the entire system.This article proposes a two-stage frequen-cy offset estimation algorithm based on a combination of Fast Fourier Transform(FFT)and spec-tral zoom methods,which utilizes the limited computational resources of onboard devices to a-chieve high-precision joint estimation of carrier frequency offset coarse estimation and fine esti-mation.The simulation results show that when the number of FFT points in two levels is 128 and 2048,the signal-to-noise ratio threshold of the algorithm is 8dB.When the signal-to-noise ratio is greater than this threshold,the estimation accuracy of the algorithm is equivalent to that of the FFT based frequency offset estimation algorithm,with a normalized frequency variance of 10-10,which is superior to the phase increment based frequency offset estimation algorithm.At this moment,compared to the frequency offset estimation algorithm based on FFT,the real number multiplication and addition times of the algorithm proposed in this article have been re-duced by 25.17％and 55.19％,respectively,the algorithm complexity has been greatly re-duced.
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