| 摘要 |
PURPOSE:To suppress the distortion of the output of a decoder produced while a fault occurs and when the faulty condition is eliminated, by providing a circuit abnormality detector for detecting abnormality in a transmission line in a differential pulse code modulator. CONSTITUTION:Whether all (k) pieces bits are '1' or '0' is inspected at every sample value and when coincident with either one condition, a code abnormality detecting circuit 17 outputs a significant signal. Then a counter controlling circuit 18 controls a counter circuit 19. Namely, upon receiving a significant signal from the code abnormality detecting circuit 17, the counter circuit 19 starts counting and at the moment when the signal is exhausted, resets the count. Thereafter, the count value 22 of the counter circuit 19 is compared with a threshold 24 set by a threshold setting circuit 23 in magnitude at a comparator circuit 21 and the abnormality of this circuit is detected.
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