基于PSTN网的远程多媒体监控技术，其关键是针对监控应用要求，在保证一定的图象和语音质量的同时，对图象与语音以尽量高的压缩率进行压缩，以及对图象与语音压缩进行实时处理，在所分析的基于PSTN的远程多媒体监控系统中，图像和语音压缩处理是采用H．263和G．732．1协议，首先介绍了该系统组成结构；然后在简要介绍基于H．263和G．732。1协议的图像与语音压缩算法的基础上，进一步讨论了针对远程多媒体监控的应用要求，基于图象与语音压缩的若干考虑，着重讨论和介绍了该系统的关键组成部分，即多媒体远程监控终端机的设计与实现，提出了基于高速DSP技术的图象与语音压缩实时处理的关键技术及所采取的措施，并对系统的主要性能进行了概略的介绍。

In the application of remote multimedia surveillance based on PSTN(Public Switching Telephone Network), one of the key technologies is the compression of video and speech data stream at a ratio as high as possible, while the quality of the video and speech are ensured for the surveillance application; Other key technologies are such as the real time processing of the compression of video and speech data stream. The PSTN based remote multimedia surveillance system, which is introduced in the article, compresses the video data stream based on the protocol H 263 and speech data stream based on the protocol G 723 1. The article first introduces the architecture of the system. Then after a short introduction to the H 263 and G 723 1 protocols based video and speech compression algorithms, some considerations with the video and speech compression are discussed for the requirements of the remote multimedia surveillance application. Further, the design and realization of the remote surveillance terminal, which is the key part of the system, are introduced with details. Also the key technology and method of the real time processing of speech and video compression based on DSP(Digital Signal Processor) are presented. As a conclusion, the main performances of the system are reported at the end of the article.