Pulse transmitting non-linear junction detector
First Claim
1. A method of detecting the presence of a non-linear junction, the steps of the method comprising:
- transmitting a transmit signal at a transmit power level and a transmit frequency;
receiving and sampling a second harmonic signal and a third harmonic signal that were re-radiated by a non-linear junction at harmonic frequencies of the transmitted signal with an analog-to-digital converter to produce sampled values;
examining the sampled values to determine if a non-linear junction is present; and
comparing the sampled values of the second and third harmonic signals to determine if a detected non-linear junction is formed by two dissimilar metals or a semiconductor.
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Accused Products
Abstract
A non-linear junction detector designed for counter surveillance measures achieves superior performance by transmitting a series of pulses and receiving harmonics of the transmitted pulse signals that are re-radiated by a non-linear junction such as would be found in an eavesdropping device containing a semiconductor. The transmit power of the series of pulses is varied and the amplitudes of the harmonics received at the different power levels are compared to determine the type of non-linear junction detected. The received harmonic signals are demodulated to create signals having a frequency in the audible range of human ears. The demodulated signals are broadcast so that an operator of the non-linear junction detector can audibly distinguish between the noise responses produced by the different types of non-linear junctions. The harmonic signals are analyzed to determine if the harmonic, signals correspond to signals produced by a known type of non-linear junction device such as a video camera or tape recorder. Data generated by the non-linear junction detector is displayed to an operator of the detector and may be stored for later analysis.
125 Citations
25 Claims
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1. A method of detecting the presence of a non-linear junction, the steps of the method comprising:
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transmitting a transmit signal at a transmit power level and a transmit frequency; receiving and sampling a second harmonic signal and a third harmonic signal that were re-radiated by a non-linear junction at harmonic frequencies of the transmitted signal with an analog-to-digital converter to produce sampled values; examining the sampled values to determine if a non-linear junction is present; and comparing the sampled values of the second and third harmonic signals to determine if a detected non-linear junction is formed by two dissimilar metals or a semiconductor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of detecting a non-linear junction comprising:
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transmitting a transmit signal containing a modulated tone; receiving a second and a third harmonic signal in response to the transmitted signal; examining the second and third harmonic signals to determine if the modulated tone is present in the harmonic signals; indicating the presence of a non-linear junction if the modulated tone is detected in the harmonic signals; and comparing the second and third harmonic signals to determine if a detected non-linear junction is formed by two dissimilar metals or a semiconductor. - View Dependent Claims (21, 22)
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23. A method of detecting the presence of a non-linear junction, the steps of the method comprising:
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transmitting a transmit signal at more than one transmit power level; receiving the amplitude of at least a second and a third harmonic signal at a second and third harmonic frequency of the transmit signal that were re-radiated in response to the transmit signal being transmitted; examining the amplitudes of the harmonic signals received in response to the transmit signals being transmitted to determine if a non-linear junction has been detected; and comparing the relative amplitude levels of the second and third harmonic signals received at the different transmit power levels to discriminate between a non-linear junction formed by two dissimilar metals and a non-linear junction formed in a semiconductor. - View Dependent Claims (24)
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25. A method of detecting the presence of a non-linear junction, the steps of the method comprising:
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transmitting a first transmit signal having a first frequency; receiving first harmonic signals at harmonic frequencies of the first transmit signal; transmitting a second transmit signal having a second frequency; receiving second harmonic signals at harmonic frequencies of the second transmit signal; examining at least one of the first and the second harmonic signals to determine if a non-linear junction is present; and comparing the first and second harmonic signals to determine if a detected non-linear junction is formed by two dissimilar metals or a semiconductor.
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Specification