| 摘要 |
PURPOSE:To prevent undesired high-cut action, separation control action, etc. by comparing the outputs of a subtractor circuit which subtracts the DC voltage from the S meter output voltage when a control signal is produced and then selecting an antenna. CONSTITUTION:Minus wave detection circuits 7A and 7B produce the DC voltages VA and VB corresponding to the AC components of the S meter output. The level discriminating circuits 8A and 8B produce control signals only when the levels of the VA and VB exceeds the reference voltage levels VRA and VRB respectively. The arithmetic circuit 9A and 9B subtract the VA and VB from the S meter output voltages VSA and VSB when the circuits 8A and 8B produce control signals. A comparison control circuit 10 sends the selection signal to an IF selection circuit 4 for selection of a channel A in the case of VSA-VA> VSB-VB and then a channel B in the case VSA-VA<VSB-VB respectively. At the same time, the circuit 10 sends a signal to an MPX stereo demodulator 6 for execution of a high-cut action and a separation control action. In other words, no control signal is produced unless the DC voltage exceeds the reference voltage. |
