| 摘要 |
PURPOSE:To prevent the generation of cross talk, by blocking the operation of a transmitter even in a call operation at busy time of other group and informing the busy state to an operator through the generation of alarm tone. CONSTITUTION:A noise squelch circuit 18 produces an output ''1'' when a carrier wave input is present and generates ''0'' at the other state. A tone squelch circuit 19 produces an output ''1'' when it receives tone from the station of the group and generates an output ''0'' in the other case. During the communication of other group, the output of the gate 20 is at ''1'' and the gate 21 is in a waiting state, then if a press-talk switch 11 turns on, the output of the gate 21 is at ''1'', an alarm generator 22 is operative and an alarm signal is given to a speaker 17. On the other hand, since the gate 12 is at inhibiting state, no transmitter 14 is operated. |
