基于DSTFT的PCM／FM信号软件化解调方法研究

根据PCM／FM信号的特点，提出一种基于离散短时傅里叶变换（discrete short time Fourier transform，DSTFT）的软件化解调方法：首先利用DST-FT计算PCM／FM信号的0、1频点的频谱能量，然后通过比较2个频点频谱能量的大小实现信号的判决；详细论述此种解调方法的基本原理和实现过程，提出采用小数形式的频点来提高解调精度；利用C＋＋语言编程实现了该解调方法，并用从实装设备采集的PCM／FM信号对解调软件进行测试。测试结果表明：该方法对PCM／FM信号具有较好的解调性能，且实现原理简洁，运行效率较高，具有一定的工程应用价值。

Research on Method of Software Demodulation for PCM/FM Signal Based on DSTFT

According to the characteristics of PCM/FM signal, a new method of software de-modulation based on discrete short time Fourier transform（DSTFT） is presented. Firstly, the spectrum energies of 0/1 frequency of PCM/FM signal are computed by DSTFT. Then, the signal is demodulated by comparing the spectrum energies of the two frequencies. The basic theory and the course of realization of the system are explicated in this paper. In order to improve the demodulation precision, the two frequencies are used fraction form. Finally, the demodulation method is programmed by C＋＋, and the demodulation software is tested with the PCM/FM signal sampled from the real equipment. The test result indicates that the method has better performance and high efficiency for the factual PCM/FM signal. The method has a bright future for application in demodulating PCM/FM signal.