| 摘要 |
PURPOSE:To prevent service impossibility dependent upon increment of temporary peripheral noise, by providing a press-to-talk switch, which determines the service direction, in the master machine and by operating this switch as an alternate service unit. CONSTITUTION:In the receiving waiting state, the input in input terminal SA is 1, and switch circuits S1 and S2 are turned off, and transmission and receiving are turned off. If private service is released after channel selection, the input in input terminal SA is 0, and the input in input terminal SB is 1, and switch circuits S1 and S2 are turned on, and the channel becomes louding simultaneous service. If private service is set after channel selection, outputs of AND circuits G2 and G6 are operated alternately by the input of input terminal SC, and therefore, only the receiving-side or transmission-side channel is turned on, so that the receiving gain for alternate service can be increased. |
