单工电台接入有线电话网的无回波抵消设计

单工电台接入有线电话网在军事和民用上都有很大的需求，在设计中面临着两个问题，一是有线端二／四转换引入的回波影响，二是话音检测，传统的方案采取自适应顺波抵消技术来解决第一问题，提出了一种基于可靠的话音检测，通过交换控制软件来实现的接入方案，其回顾了自适应回波抵消这一难题，具有软，硬件代价低的优点，该设计方案现已应用于实际的产品中，性能良好。

Design of Simplex Transceiver Accessing to Telephone Network without Echo Cancel

Design of simplex transceiver accessing to telephone network is very important in military and civil application. Designer will face two problems, the first being echo effect induced by 2-4 transition at wire side, and the second VAD(voice active detection). The traditional method applies AEC(adaptive echo cancel) technology to solving the first problem. The paper presents a kind of accessing scheme, which is based on reliable VAD and realized by switch control software. The scheme avoids difficulties of AEC, so involving lower hardware and software costs. It has been applied to practcal products, and achieved favorable performance.