| 摘要 |
PURPOSE:To detect at a low cost whether a RAM data is normal or abnormal, by recording in advance a tone signal in a RAM, calling the tone signal in the RAM in accordance with a call from the other party, and detecting whether it is normal or abnormal. CONSTITUTION:A CED signal and a sound signal are set to a RAM 6 in an audio response unit 1. In this state, a tone generating circuit 3 is driven by an output instructing signal, and a sine wave (CED signal) of a prescribed frequency is outputted. A tone signal from the circuit 3 is sound-recorded in the RAM 6 through an adder 4, a hybrid transformer 12, a tone detecting circuit 5, and the audio response unit 1. After a prescribed time elapses, the operation of the circuit 3 is stopped by the output instructing signal, a relay contact 10 is closed and a voice from a telephone set is sound-recorded in the RAM 6. By a transmission from the other party side, the unit 1 is set to a reproducing mode, and the relay contact 10 is opened. The tone signal from the unit 1 leaks to a circuit of the adder 4 and the circuit 5. When a check use tone is reproduced and the tone is detected by the circuit 5 within a prescribed time, the contents of the RAM 6 are decided to be correct and the contact 10 is closed.
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