| 摘要 |
PURPOSE:To detect the abnormality of an analog circuit part and to perform the precise decision for signal confirmation, by providing a means, which detects that the A/D conversion value is not changed over a certain width for a certain time, in the output of the last stage of the analog circuit part which detects the discrimination signal of a CM broadcast. CONSTITUTION:The discrimination signal of unit broadcast information is superposed to the low frequency region of the sound of this unit broadcast information and is broadcasted, and the discrimination signal is received by an analog circuit consisting of BPFs 351-353, rectifying and smoothing circuits 361-363, and A/D converters 371-373. The discrimination signal is digitized in converters 371-373 in accordance with sampling pulses from a sampling timer 38, and the digital signal is applied to a microprocessor 39. Abnormality detecting circuits 501-503 are provided in the output side of converters 371-373, and it is detected in circuits 501-503 that A/D conversion values are not changed over a certain width for a certain time, and the abnormality of the analog circuit is reported to the processor 39. Thus, the precise decision for confirmation of the CM discrimination signal is performed. |
