传统测频方法对多进制相移键控(multiple phase shift keying，MPSK)在信号采样数据非线性变换后直接进行快速傅里叶变换，方法简单易实现，但频率测量范围小且精度差，无法适应由 目标高速机动、通信距离远导致的MPSK信号频率动态大、信噪比(signal to noise ratio，SNR)低的应用场景。针对该难题，提出了一种"粗+精"处理架构的高精度测频算法，粗测状态采用功率谱加窗法粗略测量多普勒频移，精捕状态采用变化率分槽修正和滑动分组平均压缩实现多普勒频移及其变化率的双重精确测量。试验与分析结果表明，所提算法在大频率动态、低SNR条件下，多普勒频移测量精度达到Hz级、多普勒变化率测量精度达到Hz/s级，显著提高了MPSK信号在大频率动态和低SNR环境下的测频精度和检测灵敏度。
High-accuracy frequency measurement algorithm for weak MPSK signals under large frequency dynamic environment
The fast Fourier transform(FFT)is directly used after the nonlinear transforming of the sampled data of multiple phase shift keying(MPSK)signals in the traditional frequency measurement algorithm,which is simple to structure and easy to implement,but is hardly adapted to the application environment of large frequency dynamic and low signal-to-noise ratio(SNR)of MPSK signals resulting from target high-speed maneuvering and long-range communication due to poor accuracy and small scale of frequency measurement.A high-accuracy frequency measurement algorithm based on the process structure of the coarse and fine state is proposed in order to resolve the problem above.The power spectrum windowing method is used to roughly achieve the Doppler frequency shift in the coarse state.The method combining the rate-slotting correction with the sliding grouping and average compression is used to accurately measure the Doppler frequency shift and its range rate in the fine state.The experiment and analysis result verify that the proposed algorithm can achieve the Doppler frequency shift measurement precision up to Hz level with the Doppler change rate measurement precision up to Hz/s level in large frequency dynamic and low SNR environment,which effectively increase the frequency measurement accuracy and detection sensitivity of MPSK signals in large frequency dynamic and low SNR environment.
weak multiple phase shift keying(MPSK)signallarge frequency dynamiclow signal to noise ratio(SNR)high-accuracy frequency measurementfast Fourier transform(FFT)
万方数据
维普
