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来源：百度知道 编辑：UC知道 时间：2024/06/08 12:05:16
本文基于数字专用移动无线电DPMR协议，设计了DPMR物理层4FSK基带调制解调方式的程序实现。
文章从数字对讲机的国内外发展入手，了解其所用技术标准。并给出了在此协议下的4FSK调制解调的实现过程。4FSK调制解调就是把含有同步码的二进制符号流先按照协议中的规则依次对应成四电平符号-3，-1，1，3，即信号的幅度为这些值，然后再通过平方根升余弦滤波器进行卷积滤波以实现调制解调的目的。
本文将通过对调制的符号和偏差，平方根升余弦滤波器的介绍，以及最终4FSK调制解调级联原理的介绍，可以了解DPMR物理层4FSK的基本原理。系统的特点是可以根据用户的需要方便地进行功能的扩展，当需要改进时，只要在相应的部分添加新的方法即可，而不必对原系统进行太多的修改。程序的结构也显得非常的清晰。
The main body of a book have designed that DPMR physics 4 FSK bases belt modulation demodulation way procedure comes true owing to that figure special use moves the radio DPMR agreement. The article is developed from figure intercom home and abroad starting , is knows what whose uses technical norms. And have given that here the agreement is lower 4 FSK out the process modulating the realization decoding. 4 FSK modulate demodulation being 3- , 1 , 1 , 3 with the binary system sign stream containing synchronism yard first according to that regulation take turns correspondence in agreement becomes four electrical level signs- , are that the signal extent is these value, wave filtering carrying out a convolution then again by square root litre of cosine wave filter to realize the purpose modulating demodulation's. Sign and deviation the main body of a book is modulated face to face