| 摘要 |
A closed space monitor system monitors the closed space by detecting a change in the air flow and the volume change of the closed space. The closed space monitor system includes a transmitter for generating and transmitting a compression wave of gas, a receiver for receiving the compression wave of gas, a inverting amplifier for amplifying the signal from the receiver via an electric current-voltage conversion portion, and automatic gain control portion. The amplified signal from the receiver is transmitted from the transmitter for generating the stationary wave in the closed space.
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