为了使电力系统通信设备的呼叫装置更加使用方便工作可靠,我们研制了以按键电话机发出双音频呼叫信号进行选择接收的音频选号装置。多频接收器是音频选号装置中的主要部件之一,它的作用是选择接收对方发来的双音频信号,使相应的被叫用户动作。 关于音频选号装置已另有文章介绍,本文专门介绍多频接收器的电路原理,防干扰问题,以及一些国外情况。 In order to make the calling device of the power system communication equipment more convenient and reliable to work, we have developed an audio serial number selection device which sends and receives double audio call signals by the key telephone. Multi-frequency receiver is one of the main components of the audio signal selection device, its role is to choose to receive the other side sent a double audio signal, so that the corresponding called user action. About the audio frequency selective sign device has another article introduction, this article specially introduced the multi-frequency receiver circuit principle, the anti-interference question, as well as some foreign situations.