基于数字滤波的低频时码秒脉冲抖动平滑方法研究

低频时码授时信号在接收时，由于环境等因素的影响会导致解调得到的低频时码秒脉冲出现抖动。为减小该抖动现象对低频时码定时精度的影响，基于我国低频时码授时系统(BPC),研究并设计基于数字滤波的秒脉冲抖动平滑方法，通过仿真实验，验证分析了最小均方误差(LMS)自适应滤波算法和卡尔曼滤波算法的有效性和抖动平滑性能。结果表明，低频时码秒脉冲的抖动现象可以通过BPC 1PPS (one pulse per second)和本地1PPS之间的相位差波动情况反映；LMS自适应滤波算法和卡尔曼滤波算法对BPC 1PPS的抖动平滑处理均有明显效果，卡尔曼滤波算法的抖动平滑效果更优，但存在一定的收敛时间，LMS自适应滤波算法的滤波结果响应速度快，但抖动平滑性能受滤波器阶数的影响。所以，在实际应用中，应根据实际需求选择合适的滤波器及相关参数。

Research on jitter smoothing method of low-frequency time-code 1PPS based on digital filtering

When the low-frequency time-code signal is received, due to the influence of environmental factors, the demodulated low-frequency time-code 1PPS(one pulse per second) will jitter. In order to reduce the influence of low-frequency time-code 1PPS jitter on timing accuracy, based on low-frequency time-code timing system (BPC) in China, an 1PPS jitter smoothing method is studied and designed on the basis of digital filtering. Through simulation experiments, the effectiveness and jitter smoothing performance of least mean square (LMS) adaptive filter and Kalman filter are verified and analyzed. The results show that the jitter of BPC 1PPS can be reflected by the phase difference fluctuation between BPC 1PPS and local 1PPS. Both LMS adaptive filter and Kalman filter have obvious smoothing effects on the jitter of 1PPS, among which Kalman filter has better jitter smoothing results but with a convergence time. The filtering result of LMS adaptive filter has a short response time, but its jitter smoothing performance is affected by the order of filter. Therefore, in practical applications, appropriate filters and related parameters should be selected according to actual needs.