| 摘要 |
PURPOSE:To make clear reception without breaks of sound possible during the reception of a receivable electric field by turning off the operation of a squelch circuit during the reception of the receivable electric field without providing an adjusting knob for varying the operation reference especially when a channel discriminating circuit and the squelch circuit are operated. CONSTITUTION:At a reception time, a positive voltage (high-level signal) is applied from a microcomputer 2 to a gain control circuit 13 through an output line 6. As the result, a diode 14 is turned on, and a capacitor 16 is grounded. At this reception time, an emitter resistance R2 and the capacitor 16 are connected in parallel, and equivalently, the value of said emitter resistance R2 is reduced. Therefore, the signal supplied to the microcomputer 2 through an input line 5 is in the low level during the reception of the receivable electric field, and consequently, the signal applied to a diode 7 is in the low level. Thus, a preamplifier 9 is held in the turnon state during the reception, and breaks of sound are not generated then. |
