基于数字包络检波的RNSS通道时延标定方法

Delay Calibration of RNSS Signal Channel Based on Digital Envelope Detection

提出一种采用数字处理的时延测试方法,用于对导航卫星导航信号发射通道分数码片时延的精确测量。该方法是通过高速A/D（模/数）转换器,对导航卫星下行的BPSK（二进制相移键控）信号和卫星导航秒脉冲进行双通道采样,读取采样数据并进行数据处理。根据秒脉冲信号触发门限上升沿确定时延测量起点,对BPSK采样数据进行平方律检波,获取码片换相点,计算换相点和秒脉冲之间的分数码片时延,并进行滤波器时延校准,从而得到导航卫星发射链路的分数码片时延,该方法不需要进行伪随机信号的捕获和跟踪,测量精度主要取决于采样器采样率。通过在测试中使用一根校准电缆对该方法进行验证,验证结果表明,采用本文提出测试方法的测量误差优于0.3ns。

An absolute delay measurement method based on digital signal processing is proposed for accurate measurement of the fractional chip delay of the transmission channel of navigation satellites.The downlink Binary Phase Shift Key signals and pulse per second signals from a navigation satellite are sampled with high speed analog-to-digital converters in dual channels and are then processed with a digital signal processing algorithm to determine the phase transform point of change of the chip level.The fractional chip delay is obtained after group delay of the filter is calibrated.Acquisition and tracking of the pseudorandom range noise signal is not necessary and the measurement accuracy mainly depends on the sampling rate of sampler.A calibrated cable is used in validation test of the method and as shown by the results,the measurement error is less than 0.3 ns.