Patent ID: 9208365
Filing Date: 2015-12-08
Classification: G06K,G07B,G08G

Abstract:
1. An interrogation system to wirelessly interrogate wireless transponders, comprising: at least one antenna; a transmitter communicatively coupled to the at least one antenna and operable to transmit interrogation signals at each of a plurality of frequencies in a wireless communications frequency band; a receiver communicatively coupled to the at least one antenna to receive responses to the interrogation signals; and a controller communicatively coupled with the transmitter and the receiver and configured to: determine a first and a second derivative of signal strength of the received responses with respect to frequency over at least two of the frequencies, determine a first and a second derivative of phase of the received responses with respect to frequency over at least two of the frequencies, and determine at least one of a distance between the at least one antenna and a wireless transponder that responds to the interrogation signals, a bearing of the wireless transponder with respect to the at least one antenna or a speed based at least in part on the determined first and the determined second derivatives of signal strength of the received responses with respect to frequency and the determined first and the determined second derivatives of phase of the received responses with respect to frequency.