| 摘要 |
PURPOSE:To attain correct decision of talking quality of a talking channel by providing a limiter circuit so as to suppress the noise level to a prescribed level thereby decreasing the deviation of detection level of beat and preventing malfunction of an interference wave detecting circuit. CONSTITUTION:An intermediate wave input signal from a receiver of a radio telephone set decision the level of talking quality is subject to elimination of a signal being at a prescried level or over by a limiter circuit 10 so as not to be inputted to a high level signal to an amplifier 11. The level set to the limiter circuit 10 is set to a level having a sufficiently small noise and at which the talking quality is deteriorated by a disturbance signal only. The peak level of the noise included in the signal amplified by the amplifier 11 is a level allowing a comparator 13 to output a high level sufficiently tentatively but when the signal is rectified by a rectifier circuit 12 because of noise spike, the voltage becomes an output lowered than the reference voltage at the comparator 13. Thus, even when the input electric field of the receiver is lowered, the level of beat generated depending on the difference between a desired wave and a disturbing wave is not apparently increased. |
