| 摘要 |
PROBLEM TO BE SOLVED: To detect the existence of a facility to perform any illegal action inside an automatic teller machine(ATM) or mechanical revise for the worse in the other style by determining whether an acoustic signal is changed or not and detecting revising to the ATM. SOLUTION: A speaker 4 provided in an ATM 2 is electrified or excited from a signal generator 5. A microphone 7 receives a signal from the speaker 4 and extracts it with a signal detector 9. The signal generator 5 generates a white noise. When the state of not revising the ATM 2 for the worse is known, in order to detect the existence of a mechanism 13, the white noise generated by the speaker 4 is sampled and an initial signal is first detected and recorded. After every operation of the ATM 2, the signal generator 5 is electrified again and the detected signal is compared with a standard signal. When there is a remarkable difference between these two signals, it shows that the ATM 2 is revised for the worse, and an alarm signal is next generated.
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