voice frequency telegraphy 音频电报

high-frequency telegraphy [通信] 高频电报学

medium-frequency telegraphy 中频通报

audio frequency telegraphy [通信] 声频电报机

voice frequency telegraphy equipment 音频电报设备

multi-channel vioce frequency telegraphy 多路音频电报制

Voice-frequency telegraphy on radio circuits 无线电路上的音频电报

voice e frequency telegraphy 音频电报

frequency-shift telegraphy 频移电报技术 ; 移频电报 ; 移频电报技术