Method and apparatus for detecting and locating a concealed listening device
First Claim
1. An apparatus for detecting the presence or absence of a concealed listening device wherein the concealed listening device receives an acoustic signal and then wirelessly transmits an electromagnetic version of that acoustic signal over the air to a remote receiver, said apparatus comprising:
- a radio receiver for measuring the signal strength of a first electrical signal in the radio frequency band to which said radio receiver is tuned;
a microphone for detecting and converting the acoustic signal into a second electrical signal; and
a controller, coupled to said radio receiver and said microphone, for tuning the radio receiver within the radio frequency band, said controller comprising means for determining the cross correlation between an auto correlation of said first electrical signal and an auto correlation of said second electrical signal to determine the presence of the concealed listening device.
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Accused Products
Abstract
A method and system for detecting the presence, and the location of, a concealed listening device. In the method, the acoustic signal from the actual acoustic source and electromagnetic signals in the radio frequency band (containing the electromagnetically-transmitted version of the acoustic signal on an unknown frequency) are obtained and an average cross correlation of the auto correlation of each of these two signal types is derived for determining whether a concealed listening device is even present and, if so, the frequency of the electromagnetically-transmitted version. The method then utilizes timed pulse responses of a plurality of acoustic transducers, as well as a distinguishing function, to determine the location of the concealed listening device. In the system, a controller controls the operation of a radio receiver, a microphone and an arrangement of acoustic transducers in accordance with the method described above.
40 Citations
36 Claims
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1. An apparatus for detecting the presence or absence of a concealed listening device wherein the concealed listening device receives an acoustic signal and then wirelessly transmits an electromagnetic version of that acoustic signal over the air to a remote receiver, said apparatus comprising:
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a radio receiver for measuring the signal strength of a first electrical signal in the radio frequency band to which said radio receiver is tuned; a microphone for detecting and converting the acoustic signal into a second electrical signal; and a controller, coupled to said radio receiver and said microphone, for tuning the radio receiver within the radio frequency band, said controller comprising means for determining the cross correlation between an auto correlation of said first electrical signal and an auto correlation of said second electrical signal to determine the presence of the concealed listening device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for detecting the presence or absence of a concealed listening device wherein the concealed listening device receives an acoustic signal and then wirelessly transmits an electromagnetic version of that acoustic signal over the air to a remote receiver, said method comprising the steps of:
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(a) measuring the signal strength of a first electrical signal in the radio frequency band to which said radio receiver is tuned; (b) detecting and converting the acoustic signal into a second electrical signal; and (c) determining the cross correlation between an auto correlation of said first electrical signal and an auto correlation of said second electrical signal to determine the presence of the concealed listening device. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification