Debugging arrangement
AssigneeSture Risberg
InventorsSture Risberg, Alf Lindgren, Kjell Rixon, Rickard Wallden, Bengt Brundin
Life of this patent
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Abstract
Method and apparatus for detecting the presence of a surreptitiously placed radio transmitter or bug. An audio tone signal is transmitted within the confined space containing the bug, and the tone signal has a predetermined frequency and a predetermined amplitude. The tone signal energizes the microphone of the bug, causing it to transmit a radio frequency signal which is modulated according to the tone signal. The radio frequency is then demodulated and the resulting demodulated signal is applied to a narrow pass band filter which is tuned to the audio tone signal. The output of the filter is sensed to determine the presence of the bug.
Claims9
A method for detecting the presence within a confined space of a covert radio transmitter or "bug" having a microphone comprising the steps of:
- transmitting within said confined space at least one audio tone signal having a predetermined frequency and a predetermined amplitude,
- receiving radio frequency signals generated by said bug and modulated by said audio signal,
- demodulating said received radio frequency signals and applying said demodulated signals to a narrow pass-band filter which is tuned to said audio tone signal,
- and sensing the output of said filter to provide a distinctive indication of the presence of a bug.
Apparatus responsive to the presence of a covert radio transmitter or "bug" within a confined space having a microphone including:
- tone generating means for generating a tone with a predetermined frequency,
- a loudspeaker for transmitting said tone within said confined space with a predetermined amplitude,
- a receiver responsive to radio frequency including a low-frequency amplifier for amplifying said tone and a narrow band-pass filter tuned to pass said tone signal,
- and means responsive to the amplitude of the output of said filter.
Dependencies are inferred from the claim text.