低轨卫星TDMA信号侦收解调算法设计

Algorithm of Intercept and Demodulation of TDMA Signal of Low Earth Orbit Satellite

按照低轨卫星数据传输的特点,设计一种格式的TDMA信号,并以此信号为例介绍TDMA信号侦收解调中的系列问题:信号检测、多普勒频移测量、载波恢复和定时恢复。其中多普勒频移的测量采用LP方法,频率测量误差小于100Hz;载波恢复采用判决反馈环路,能够很好地对残余频差和相差进行捕获和跟踪;定时恢复采用数据转换跟踪环。用接收到TDMA通信数据对算法进行了验证,能够达到很好的解调效果。

This paper designs a kind of TDMA signal according as the characteristics of low earth orbit satellite data transmission, and take this signal for example to introduce the issues occurring in intercept and demodulation algorithm for TDMA, such as signal detection, Doppler offset measurement, carrier recovery and timing recovery. The method of Doppler offset measurement is LP and the frequency measurement error is less than 100Hz. Carrier recovery uses decision feedback 2nd order PLL which can capture remainder frequency and track phase error quickly. Timing uses data transition tracking loop. The demodulation algorithm has a good performance by using the real signal.