| 摘要 |
PURPOSE: To detect ultrasonic wave over a wide dynamic range by providing an ultrasonic sensor with a preamplifier having gain variable stepwise. CONSTITUTION: Ultrasonic sensors 20 are arranged along piping 10-14 coupled through valves 16, 18. An ultrasonic wave is generated from a leakage in the piping system, if any. The sensor 20 converts the ultrasonic wave through a transducer 21 into an electric signal which is amplified through a preamplifier and further converted into a current signal which is then transmitted through wires 31, 33, -V to a central controller/analyzer 30. When a signal received from the sensor 20 is saturated, the controller/analyzer 30 delivers a signal for reducing the gain of preamplifier to the sensor 20. The sensor 20 reduces the gain stepwise depending on the signal thus detecting ultrasonic wave over a wide dynamic range. The transducer 21 is disposed in a housing having an opening covered with a Milar film and has resistance against outdoor environment. The controller/analyzer 30 records and display the output from sensor 20 and controls the valves 16, 18, as required. |
