| 摘要 |
PURPOSE:To make it smooth to make a call by sending a changeover tone signal to a party side when either of subscriber changes transmission over to reception in the simplex working system. CONSTITUTION:After the key station sends lock signal 2 to the subordinate station and dial tone 3 to the calling station with calling signal 1 of the calling station and the calling station sends dial signal 4 out. The key station sends simplex signal 5 out to call the called station with speech signal 6 and also to send dial tone 8 to the calling station. Once the called station answers, answer signal 9 is received by the key station and with transmitted signal 10 of the calling station, the circuit for the received signal 11 of the called station is constituted. When the calling station changes transmission over to reception, the calling station sends changeover tone signal 12 to the called station for 0.5 second and the called station generates transmission tone signal 14 by the signal for the call. |
