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目前,在我国二进制数字传输中,常在一个字码组之后插入一位奇偶校验码,查出码组中一位码的错误。在数字码中又常采用差分相移键控的调制方式,即PCM-△PSK的调制方式,但在传输信道中,由于短时间的强烈干扰或信号衰落引起一位差分码的错误,将造成二进制PCM码的成对错误。故采用这种调制方式,要恕在接收解调端利用二进码的奇偶性查出一位码的错误,往往是达不到目的的。本文针对上述情况进行了详细的分析,并提出采用对差分码极性数目的奇偶校验方法,查出差分码在传输过程中的错误。采用此种方法并不需要在现有设备上作重大修改,只需将原来的二进制奇偶码产生器稍作改变即可。
At present, in our country’s binary digital transmission, a parity code is always inserted after a word code group to find a code error in the code group. In the digital code is often used differential phase shift keying modulation, PCM- △ PSK modulation, but in the transmission channel, due to a short period of strong interference or signal fading caused by a differential code error will result Binary PCM code paired error. Therefore, the use of this modulation, in order to forgive the demodulation end of the use of binary parity code to find a code error, often can not reach the goal. In this paper, a detailed analysis of the above situation, and proposed the use of the number of parity check the number of parity to detect differential code error in the transmission process. This method does not require major changes in the existing equipment, only the original binary parity generator can be slightly changed.