一种高精度罗兰C信号数字移相算法

摘要

多路信号的数字化采样必然存在采样通道差异,从而导致合成信号相位的差异,进而影响罗兰C合成信号的信噪比及定位解算的精度.为了克服传统数字移相方法受采样率限制、移相精度不高的不足,提出了一种不受采样率限制、计算简单、容易利用复杂可编程逻辑器件/现场可编程门阵列(CPLD/FPGA)等高性能可编程逻辑器件实现的高精度数字移相方法,即使用传统数字移相方法对信号进行移点,达到两路通道信号的粗对准；在此基础上,利用基于快速傅里叶变换-逆变换(FFT-IFFT)的高精度数字移相算法,对信号进行移相,达到两路通道信号的精对准.采用该方法移相后的数据在信号合成中可以获得更高的信噪比,并在设计的罗兰C全向磁天线中获得了应用.%Differences of sampling channels in multi-channel digital acquisition will lead to phase shift of synthesized signal and lower SNR. hence, degraded positioning precision of Loran C. The ordinary digital phase shift method has the limitation in sampling rate and phase shift precision. A new method, which uses ordinary digital phase shift method for coarse alignment of two channels and the high precision digital phase shift method based on FFT-IFFT transformation for fine alignment, is designed. The scheme is not limited by the sampling rate and can easily be implemented with CPLD/FPGA. The algorithm results in synthesized signals with better SNR. The method has been applied in a Loran C omnidirectional H-field antenna.