INTERROGATOR FOR ELECTRONIC IDENTIFICATION SYSTEM Russian patent published in 2000 - IPC

FIELD: radio engineering. SUBSTANCE: interrogator used jointly with passive responder has capacitive three-point generator with parallel power supply that can change frequency in correspondence with frequency of signal from responder, VCO voltage controlled generator that can change frequency in correspondence with frequency of capacitive three-point generator with parallel power supply after delay of several cycles of signal. Delay is provided by low-pass filter of synchronous detector in phase discriminator and by digital filter capable of detection of phase difference between capacitive three- point generator with parallel power supply and VCO voltage controlled generator. It is preferable that digital filter has input circuit including matrix of flip-flops, delay line coupled to each flip-flop and providing for time delay which increases along matrix so that presence of first and second synchronization signals related to each pair of flip- flop-delay lines is ensured. If phase difference between signals is less than time delay of this delay line, flip-flop generates logic signal 0. If phase difference is greater than time delay, flip-flop generates logic signal. EFFECT: enhanced accuracy in detection of small changes of frequency in circuit showing wide-band quality factor. 7 cl, 6 dwg