| 摘要 |
PCT No. PCT/GB95/02440 Sec. 371 Date Apr. 9, 1997 Sec. 102(e) Date Apr. 9, 1997 PCT Filed Oct. 16, 1995 PCT Pub. No. WO96/12199 PCT Pub. Date Apr. 25, 1996In an apparatus and method for detecting radiation transmitters (such as "bugs" or leaky data cables), spectral records are recorded at different times and/or locations. The records are displayed graphically and compared to identify transmitters. Spurious signals, for example as caused by taxi radio transmissions, can be eliminated since these will not appear in all records. A local transmitter of the type to be detected will appear in all records for a given location, but not in records for other locations. The strength of the transmitter signal varies as the reciprocal of the distance squared, and the presence of the transmitter and its position can be located by moving the recorder and detecting the rise or fall of the displayed graphical signal. |
