| 摘要 |
The push to talk switch is controlled by two voice signals each having a different frequency spectrum. The controller includes a first amplifier (9) for amplifying voice signal transmitted from a receive/transmit microphone (15), a first voice signal modulator (20) for extracting and modulating a first voice signal, a second voice signal modulator (20) for extracting and modulating a second voice signal, a second and a third amplifier (11,14) for amplifying output signal of the modulators (20,30), a first comparator (12) for comparing a first voice signal with the amplified second voice signal, a second comparator (13) for comparing the second voice signal with the amplified first voice signal, and a controller (10) for controlling the push to talk switch according to the output signals of the comparators. |
