| 摘要 |
<p>PURPOSE:To detect abnormal places quickly, by sending a radio wave whose frequency varies in sawtooth shape inside a buried pipe, receiving its reflected wave, obtaining a beat wave by mixing the transmitted wave and the reflected wave, and frequency-analyzing this beat wave. CONSTITUTION:Transmission wave A whose frequency varies in sawtooth shape as shown in the drawing is sent by frequency sweep generator 1 from one end of buried pipe 4, such as gas pipe, into it in one direction via directional coupler 2 and antenna 3. Its reflected wave B together with transmission wave A is input to mixer-detector 5 via directional coupler 2. Here a beat wave is detected. This is amplified by amplifier 6, and then it is subjected to frequency analysis by frequency analyzer 7. By the results of this analysis, places of heap 8, bend 9 and water 10 lying at the bottom of the pipe are detected. Thus, abnormalities in the pipe is found easily and speedily.</p> |
