Radio frequency detection system and method for passive resonance circuits
First Claim
1. A system for determining the presence or absence of a passive electrical circuit which resonates at a predetermined frequency including means for radiating said electrical circuit with periodic bursts of radio frequency energy of predetermined duration having energy at said resonant frequency at a predetermined burst rate to thereby excite the electrical circuit if it is present whereby it radiates energy at said frequency, means for receiving and periodically amplifying at a rate which differs from the burst rate energy at said frequency after termination of said bursts and generating an output signal, and means connected to said receiving means to receive said output signal and provide a signal indicative of the presence or absence of a passive circuit resonant at said frequency.
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Abstract
A system for detecting passive resonant circuits in which bursts of swept radio frequency are transmitted to excite passive resonant circuits. If a circuit is resonant at a particular burst frequency, it is excited, rings and emits a radio frequency signal. Following each transmitted burst, a receiver is turned on to receive energy emitted by a resonant circuit so that if a resonant circuit is excited, its emitted energy is received and the particular resonant circuit identified.
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Citations
16 Claims
- 1. A system for determining the presence or absence of a passive electrical circuit which resonates at a predetermined frequency including means for radiating said electrical circuit with periodic bursts of radio frequency energy of predetermined duration having energy at said resonant frequency at a predetermined burst rate to thereby excite the electrical circuit if it is present whereby it radiates energy at said frequency, means for receiving and periodically amplifying at a rate which differs from the burst rate energy at said frequency after termination of said bursts and generating an output signal, and means connected to said receiving means to receive said output signal and provide a signal indicative of the presence or absence of a passive circuit resonant at said frequency.
- 5. A system for determining the presence of one or more passive electrical resonant circuits which resonate at different frequencies including means for radiating said resonant circuits with periodic bursts of radio frequency energy of predetermined duration with successive bursts in each group having a different frequency, means for receiving and amplifying energy at said different frequency after termination of said bursts to provide an output signal, said last means comprising amplifying means adapted to be switched on responsive to a control signal and means for applying a control signal to said amplifying means to switch on said amplifying means after termination of said bursts of radio frequency energy whereby said amplifier provides an output signal when there is a resonating passive circuit at a particular burst frequency, and means connected to receive said output signal and provide a signal indicative of the presence or absence of passive circuits which are resonating at one of said predetermined frequencies.
- 7. A system for determining the presence of one or more passive electrical resonant circuits which resonate at different frequencies including transmitter means responsive to a sweep voltage serving to provide an output having a swept frequency, said transmitter means also being responsive to control pulses of predetermined duration to form output bursts of said duration with successive bursts during a sweep having a different frequency, means for receiving and amplifying energy at said different burst frequency to provide an output signal, said amplifying means being adapted to be switched on responsive to control signals, means for applying control signals to said amplifying means to switch on said amplifying means after termination of each of said bursts of radio frequency whereby said amplifying means provides an output signal when there is a resonating passive circuit at a particular burst frequency, and means connected to receive said output signal and provide a signal indicative of the presence or absence of passive circuits which are resonating at one of said predetermined frequencies.
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12. A system for determining the presence of one or more passive electrical resonant circuits which resonate at different frequencies including transmitter means responsive to a sweep voltage serving to provide an output having a swept frequency, said transmitter means also being responsive to control pulses of predetermined duration to form output bursts of said duration with successive bursts during a sweep having a different frequency, means for receiving and amplifying energy at said different burst frequency to provide an output signal, said amplifying means being adapted to be switched on responsive to control signals, means for applying control signals to said amplifying means to switch on said amplifying means after termination of each of said bursts of radio frequency whereby said amplifying means provides an output signal when there is a resonating passive circuit at a particular burst frequency, a mixer connected to receive said output signal, and means providing a delayed signal to said mixer from said transmitter means for mixing with the output signal, said mixer providing an output signal indicative of the presence or absence of passive circuits which are resonating at one of said predetermined frequencies.
- 15. A system for determining the presence of one or more passive electrical resonant circuits which resonate at different frequencies including transmitter means responsive to a sweep voltage to provide an output having a swept frequency and responsive to control pulses of predetermined duration to form output bursts with successive bursts during a sweep having different frequencies to radiate said resonant circuits, means for receiving and amplifying energy at said different frequencies after termination of said bursts to provide an output signal, and means connected to receive said output signal and provide a signal indicative of the presence or absence of passive circuits which are resonating at one of said predetermined frequencies, said system including autocorrelation circuits adapted to correlate signals from successive sweeps.
Specification