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EXPRESS—NET是一个本地通信网,它包含一个输入通道和一个输出通道,各站都联结在这两个通道上。各站通过输出通道发送信号,通过输入通道接收信号。由于输入通道也联接到输出通道上,这使所有在输出通道上传输的信号,也全部在输入通道上重现,这样,可以实现同文广播通信。为了在总线上正常传输,各站须采用EXPRESS信道访问规程。这是一个分散控制型的信道访问规程,可以实现无碰撞的循环程序。另外,EXPRESS—NET所具有的某些特征,使它特别适合于声音的传输。为了实现综合传输声音和数据,文中介绍一种简便的声音/数据EXPRESS规程,这个规程能保证在任何时刻都满足声音传输对带宽和时延方面的要求,同时还保证数据传输所需要的最低频带的要求。
EXPRESS-NET is a local communications network that contains an input channel and an output channel, each station connected to both channels. Each station sends the signal through the output channel, receives the signal through the input channel. Since the input channels are also connected to the output channels, all the signals transmitted on the output channels are all reproduced on the input channels, so that the same broadcast communication can be realized. For normal transmission on the bus, each station shall use EXPRESS channel access procedures. This is a decentralized control of channel access procedures, can be achieved without collision cycle program. In addition, EXPRESS-NET has some of the features that make it particularly suitable for the transmission of sound. In order to achieve a comprehensive transmission of sound and data, the article presents a simple EXPRESS protocol for voice / data that ensures that the bandwidth and latency requirements of voice transmission are met at all times while still ensuring the lowest frequency band required for data transmission Request.