【物理】呼救信号发射机、莫尔斯电码电报通信

dot-and-dash code

dot-and-dash code telegraph transmitter

dot-and-dash code, code bar

dot-and-dash code telegraphy reception

dot-and-dash

dot-and-dash line【计】

dot-and-dash【通信】

dot-and-dash code, code disc