| 摘要 |
PURPOSE:To apply the titled circuit to a relay station not detecting a frame by inputting an output of a logical circuit and raising an alarm when a frequency is higher than a prescribed value, where low-order m bits of an A/D converter is all 0 or all 1. CONSTITUTION:The A/D converter 1 converts a base band signal BB into (n+ m)-bits and an AND circuit 2 ANDs low-order m bits of the converter 1. m Sets of polarity inverting circuits 3 invert each polarity of m bits and an AND circuit 4 ANDs the outputs of the circuits 3. Further, an OR circuit 5 ORs outputs of the circuits 2 and 4 and a discriminating circuit 6 outputs an alarm alm when the frequency where the output of the circuit 5 goes to 1 is larger than a prescribed value. Since the output of the circuit 5 goes to 1 when all the low- order m bits go to 0 or 1, the frequency is measured by the circuit 6 and a reception fault is detected depending on whether the frequency is larger than the prescribed value or not. |
