论文部分内容阅读
本文讨论了采用非同步PPM-IM方式传输4MHz电视电话的光纤实验系统的若干问题。推导了信噪比公式,特别是考虑了门限电平变动的噪声对解调信噪比的修正公式;分析了解调特性与有关参数的相互关系;给出了几个主体电路原理及系统实验结果。实验中成功地进行了话音与图象的复用和分离,这将为多中继传输中的振铃、告警和业务话路的复用提供一种简便的方法。
This article discusses some of the problems with the fiber optic experimental system for transmitting 4MHz videophones using asynchronous PPM-IM. The formula of signal to noise ratio is deduced, especially the correction formula for the signal to noise ratio of the demodulated signal considering the variation of the threshold level. The relationship between the demodulation characteristics and the relevant parameters is analyzed. Several main circuit principles and system experiments result. The successful experiment in the voice and image multiplexing and separation, which will ring for the multi-relay transmission, alarm and business path multiplexing provides a convenient way.