电离层后向散射探测中m序列和FH序列的应用

The applications of m sequence and FH sequence to ionospheric backscattering sounding

在高频电离层后向散射雷达探测中 ,由于电波传播路径长、陆空传播环境复杂 ,因此要保证接收信号具有较高的信噪比一般需要大功率的射频信号 ,或积累足够时间的接收信号。基于间隔收发相干积累雷达体制 ,首先介绍了电离层后向散射探测的相位编码脉冲压缩方法以及相关检测的基本原理 ,然后介绍了具有良好周期自相关性的 m序列和 Frank- Heimiller ( FH)序列在等间隔收发应用中的相关检测算法 ,提出了一种简单的针对 m序列的检测误差修正算法。同时给出了使用 m序列和 FH序列进行电离层后向散射探测的信号波形及其调制解调电路模块。

HF sky wave signals are subjected to long path and complex backscattering propagations before their being detected by radar. To obtain enough information from the received signals, it is necessary to transmit powerful RF signals or to accumulate received signals for a relatively long time. In this paper, we review the methods and examples of Ionospheric backscattering sounding and the basic principle of correlation detection. A correcting algorithm is put forward to improve detecting quality of m sequence. Modem circuits and signal waveforms are provided to indicate the detecting procedure of m and FH sequences. Their performance of gain and noise is discussed and the influence of mobile objects on the ability of detection is analyzed.