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为了提高低信噪比条件下再生伪码测距系统中的复合伪码时钟恢复性能,采用了一种新型的码片跟踪环.此码片跟踪环是一种改进型的数据转换跟踪环,两者之间的区别在于,码片跟踪环的Q路输出直接乘上了时钟分量,而数据转换跟踪环乘上了I路的转换检测器输出.在准方波伪码测距信号的情况下,详细分析了码片跟踪环的跟踪(均方定时抖动)性能.分析对比了不同码片信噪比条件下的码片跟踪环和数据转换跟踪环跟踪性能.分析表明,码片跟踪环和数据转换跟踪环在大信噪比条件下性能一致;而在小信噪比条件下,码片跟踪环性能明显好于数据转换跟踪环.
In order to improve the performance of composite pseudocode clock recovery in regenerative pseudocode ranging system with low signal-to-noise ratio (SNR), a novel chip tracking loop is adopted.This chip tracking loop is an improved data conversion tracking loop, The difference between the two is that the Q-path output of the chip tracking loop is directly multiplied by the clock component and the data conversion tracking loop is multiplied by the output of the conversion detector I. In the case of quasi-square-wave pseudo-code ranging signals , The performance of tracking (mean square timing jitter) performance of chip tracking loop is analyzed in detail.The tracking performance of chip tracking loop and data conversion tracking loop under different chip SNR is analyzed and compared.The analysis shows that chip tracking loop And the data conversion tracking loop has the same performance under the condition of large signal-to-noise ratio. However, the performance of the chip tracking loop is obviously better than the data conversion tracking loop under the condition of small signal-to-noise ratio.