| 摘要 |
PURPOSE:To simplify circuit constitution by allowing a control means to increase/decrease the oscillating frequency at a prescribed width, discriminating the presence of the disturbance of an adjacent station from the change in the signal strength attended with the increase/ decrease, applying switching control to a band width changeover means, thereby excluding the disturbance by the adjacent station. CONSTITUTION:An oscillated output of an oscillation means 5 and an FM reception signal outputted from an FM high frequency amplifier circuit 3 are mixed by a mixing means 4, the signal of the obtained AM intermediate frequency is supplied to an AM intermediate frequency amplifier circuit 29 and a signal intensity detection means 32 detects the signal intensity based on the intermediate frequency signal outputted from the AM intermediate frequency amplifier circuit 29. On the other hand, a control means 49 increases/decreases the setting value so as to increase/decrease the oscillating frequency of the oscillation means 5 at a prescribed width and compares mutually the change in the signal intensity attended with the increase/decrease to discriminate the presence of the disturbance in the adjacent station and applies switching control to the band changeover means 8 based on the result of discrimination thereby excluding the adjacent station disturbance. Thus, the AM intermediate frequency amplifier circuit 29 whose function is substantially to be stopped at the FM reception is utilized effectively to detect the disturbance of the adjacent station. Thus, the circuit constitution is simplified.
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