System and related circuits and methods for detecting and locating wireless communication device use within a geographical area or facility
First Claim
1. A system for detecting and locating wireless communication device use within a geographical area or facility, which comprises:
- an array of radio frequency (RF) receivers, each receiver being placed in a predetermined location in the geographical area or facility; and
a central processing unit, the receivers being in electrical communication with the central processing unit;
wherein each receiver includes;
an antenna which receives RF signals generated by wireless communication device use;
a switchable RF filter bank in electrical communication with the antenna and designed to reject out-of-band subharmonic and harmonic signals;
a variable attenuator in electrical communication with an output of the RF filter bank to extend the dynamic range of the receiver and to test for the presence of harmonic distortion effects;
a mixer in electrical communication with the RF filter bank to downconvert sidebands of the RF signal received by the antenna;
a local oscillator in electrical communication with the mixer;
a bandpass filter in electrical communication with an output of the mixer which sets the resolution bandwidth of the system;
a detector in electrical communication with an output of the bandpass filter, the detector outputting a voltage proportional to the signal power received thereby, which voltage is proportional to the level of the RF signal received by the antenna; and
a microcontroller in electrical communication with the central processing unit, the local oscillator, the filter bank and the attenuator, the microcontroller further converting the output voltage of the detector to a digitized power level measurement.
3 Assignments
0 Petitions
Accused Products
Abstract
A system for detecting and locating illicit cellular telephone use within a facility includes an array of radio frequency (RF) receivers, each receiver being placed in a predetermined location in the facility, and a central server, the receivers being in electrical communication with the central server. The server commands a group or groups of receivers to tune to a frequency of interest and to perform detailed sample rate measurements of the RF signal level received at the receivers. The array of receivers is organized into a plurality of measurement areas covering widely separated areas of the facility or different buildings of the facility, and the plurality of receivers of a measurement area is organized into a plurality of measurement groups covering areas of approximately uniform RF propagation conditions. Each receiver scans a frequency band of interest non-synchronously and independently of the other receivers in the array. Also, each receiver is preferably a direct-conversion receiver.
7 Citations
35 Claims
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1. A system for detecting and locating wireless communication device use within a geographical area or facility, which comprises:
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an array of radio frequency (RF) receivers, each receiver being placed in a predetermined location in the geographical area or facility; and a central processing unit, the receivers being in electrical communication with the central processing unit; wherein each receiver includes; an antenna which receives RF signals generated by wireless communication device use; a switchable RF filter bank in electrical communication with the antenna and designed to reject out-of-band subharmonic and harmonic signals; a variable attenuator in electrical communication with an output of the RF filter bank to extend the dynamic range of the receiver and to test for the presence of harmonic distortion effects; a mixer in electrical communication with the RF filter bank to downconvert sidebands of the RF signal received by the antenna; a local oscillator in electrical communication with the mixer; a bandpass filter in electrical communication with an output of the mixer which sets the resolution bandwidth of the system; a detector in electrical communication with an output of the bandpass filter, the detector outputting a voltage proportional to the signal power received thereby, which voltage is proportional to the level of the RF signal received by the antenna; and a microcontroller in electrical communication with the central processing unit, the local oscillator, the filter bank and the attenuator, the microcontroller further converting the output voltage of the detector to a digitized power level measurement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification