| 摘要 |
PURPOSE:To prevent mis-detection of a failure of receiver by ORing exclusively the result of comparison of a noise squelch output and a carrier squelch output respectively with a lower limit value so as to block the discriminating operation of a failed receiver with the output of operation. CONSTITUTION:In a figure (a), 10 is a squelch circuit of the 1st receiver and 12 shows a squelch circuit of the 2nd receiver. A squelch gate signal from the squelch circuits 10, 12 is applied to an exclusive OR gate 18 via lines 14 and 16 and ORed exclusively. A figure (b) shows the constitution of the squelch circuits 10 and 12. In the figure (b), the exclusive OR between the output of the 1st detecting circuit 38 detecting whether or not the non-sound band noise component of the demodulated output of each receiver is a prescribed lower limit value or over and of the 2nd detecting circuit 40 detecting whether or not the carrier component of each receiver is a prescribed lower limit or over is operated by an exclusive NOR gate 42 to block the discrimination of a failed receiver depending on the output. |
