| 摘要 |
PURPOSE:To secure detection of the multi-path disturbance with no effect of the external noise by carrying out the multi-path detection based on the noise component composed of the higher harmonic component contained in the output of the FM demodulator. CONSTITUTION:Filter circuit HPF is connected to the output side of the FM demodulator to draw out the component outside the modulation signal band contained in the output of the FM demodulator (not shown in the figure), and at the same time the multi-path disturbance amount is indicated by meter M based on the output of circuit HPF. As a result, the indication of meter M lowers down in accordance with the scale of the noise component composed of the higher harmonic component which is caused in case the multi-path disturbance is generated. Thus the multi-path disturbance amount is indicated based on the indication lowering amount of meter M. In this case, the noise component is drawn out of the FM demodulator output, and accordingly no effect of the AM-type external noise or the like is given. As a result, an accurate indication is secured. |
