基于FPGA的PPM调制解调系统优化设计

The Optimum Design of PPM Modulation and Demodulation System Based on FPGA

为了研究PPM调制解调原理,本文设计了两种PPM调制解调系统。在解调时,系统A首先检测PPM信号的所有边沿信息,并在边沿时刻输出一个标志脉冲,然后根据此脉冲,系统A依次将输出取反,得到解调信号。而系统B则是在系统A的基础上加了一个修正模块,以此来降低对发送端的要求,其原理是,当第一个边沿信号到来时,先判断是上升沿还是下降沿,若是上升沿则维持系统A的输出,若是下降沿,则将系统A的输出取反再输出。实验结果可得:在50MHz的时钟下,本设计的两种调制解调系统均能对输入数据进行PPM调制解调,又由于系统B增加了修正模块,导致系统B比系统A的总功耗多0.13mw,逻辑资源多占用2个,但系统B相对于系统A来说,能够降低对发送端的要求。

To study the principle of PPM modulation and demodulation, we design two kinds of PPM modulation and demodulation systems. In demodulation, system A first detects all edges information of PPM signal and outputs a flag pulse at the edge time;then, based on this pulse, system A will reverse outputs in turn and gets the demodulation signal. With system B, a correction module is added based on system A to reduce the requirements for the transmitter end. The principle for system B goes like this: when the first edge signal arrives, it judges whether it is the rising edge or the falling edge;if it is a rising edge, it maintains the outputs of system A;if it is a falling edge, then it outputs the reversed outputs of system A. The experimental results show that the two kinds of modulation and demodulation systems designed in this paper can modulate and demodulate the input data under the clock of 50MHz. And because of the addition of correction module, system B’s total power consumption is 0.13mw higher, and it occupies 2 more logic units than system A does. However, system B can reduce the requirements for the transmitter end compared with system A.