| 摘要 |
PURPOSE:To inspect the sensitivity of a pager receiver with high accuracy by counting the number of pulses of a ringing tone caught by a microphone and distinguishing the ringing tone of the pager receiver from erroneous ringing tone caused by shock and vibration. CONSTITUTION:A monostable multivibrator circuit 12 outputting a pulse output having a pulse width over one period of an output signal waveform of a comparator 5 with a waveform edge of an output signal of the comparator 5 and a counter 8 counting the number of pulses of an output of the comparator 5 for an enable period of the output of the monostable multivibrator circuit 12 and connected to the output of the comparator 5 and the output of the monostable multivibrator circuit 12 are provided in addition between the comparator 5 and a latch circuit 6 in following to an amplifier 3 and a band pass filter 4 in a conventional device. Moreover, a magnitude comparator 10 is provided, which compares the output of the counter 8 with a setting value 11 and gives an enable output when the output of the counter 8 gets larger than the setting value. Thus, erroneous detection when shock and vibration are given to a shielding box 1 during the inspection is prevented. |
