JPS5563144A - Signal detecting system for calling receiver - Google Patents

Abstract

PURPOSE:To prevent the malfunction caused by the impact noise by installing the control circuit including the signal generation means which switches two gates alternately and the counting means which counts the input pulses up to the prescribed value to the calling receiver of the pocket bell or the like. CONSTITUTION:When low frequency burst signals F1 and F2 are supplied to gate circuits 1 and 4 from terminal 10 and under the signal queuing state, gate signal (e) is on with gate signal (f) off each. As a result, signal F1 passes through filter 2 waveform shaping circuit 3 through only circuit 1, and signal (b) is supplied to digital control circuit 7. At circuit 7, signal (b) is counted 12, and count end signal (d) is generated when the counting reaches the prescribed value. And signals (e) and (f) are turned off and on respectively through delay circuit 13 and mono- multi 14. Thus circuit 4 opens, and signal F2 is supplied to circuit 7 via filter 5, waveform shaping circuit 6. Circuit 7 counts 18 signal (c) supplied and amplifies 8 call signal 20 via latch circuit 19 when the counting reaches the prescribed value, thus sound generator 9 being rung. In such way, the signals are processed through counting, thus preventing the malfunction due to the noise.