| 摘要 |
PURPOSE:To reduce the circuit scale and to attain inexpensive circuit by comparing the detection output of an AGC amplifier output with the detection output of the 2nd BPF output and raising an alarm when the deviation is an allowable value or above so as to save a spectrum extraction/detection section. CONSTITUTION:Reception signals from a main antenna and an SD antenna are combined and the result is outputted at a prescribed level through a BPF 4 and an AGC amplifier 5, a corresponding DC voltage is extracted by a detec tor 6 and compared with a threshold voltage by a comparator 7. On the other hand, the output of the amplifier 5 is narrowed further by a BPF 13, detected and outputted similarly by a detector 14 and inputted to a comparator 15. The output of the detector 6 is inputted to the comparator 15, where both the inputs are compared. When the deviation is within the specified value, the SD operation is discriminated to be normal and no SD alarm is sent, but when the deviation is the specified value or above, the SD operation is discriminated to be abnormal and the SD alarm is sent. |
