基于二分搜索的宽带多普勒模型信号捕获方法

A signal acquisition method in wideband Doppler model based on binary search

摘要:

针对深空通信等超高动态低信噪比通信场景中，传统信号捕获方法存在着动态范围不足、精确度不够以及使用窄带多普勒模型导致对接收信号近似精确度不高的问题，提出一种基于二分搜索的接收端采样率调整方法。使用宽带多普勒模型对接收信号进行建模，并使用扫频余弦类信号进行多普勒频偏估计和定时估计，处理多普勒伸缩后的信号与本地信号采样率不匹配的问题。对所提方法进行同步性能仿真，仿真结果表明，所提方法采用正反扫频线性调频(UD-LFM)信号，能在信噪比为-49 dB、最大多普勒频偏为2 MHz的条件下，多普勒频偏估计误差小于400 Hz，定时估计误差不超过60 ns。相比不使用本文所提方法进行直接捕获，本文所提方法具有更高的捕获精确度以及更低的信噪比门限。

Abstract:

In the ultra-high dynamic and low Signal-to-Noise Ratio(SNR) communication scenarios like deep space communication, traditional signal acquisition methods suffer from inadequate dynamic range support, insufficient accuracy, and the use of a narrowband Doppler model leading to poor approximation accuracy in the received signal. A wideband Doppler model is employed to model the received signal and a chirp signal is used for Doppler estimation and timing estimation. A sampling rate adjustment method based on binary-search is proposed for the receiver to overcome the mismatch between the Doppler-stretched signal and the local signal sampling rate. The simulation results of the synchronization performance show that the proposed method using Up-Down Linear Frequency Modulation(UD-LFM) signal is capable of achieving a Doppler estimation error below 400 Hz and a timing estimation error below 60 ns under a SNR of -49 dB and a maximum Doppler frequency of 2 MHz. Compared to direct acquiring, the proposed method bears a higher acquisition accuracy and a lower SNR threshold.