Patent ID: 8174364
Filing Date: 2012-05-08
Classification: G06K

Abstract:
1. A radio frequency identification (RFID) system that includes: an antenna; an antenna switch that is switchable into a first and second state; a phase lock loop that includes a voltage controlled oscillator, a phase detector, and a loop filter; a RFID decoder; a microcontroller or microprocessor; said voltage control oscillator in said phase lock loop connects to said antenna switch; said RFID decoder connects to said antenna switch; said antenna connects to said antenna switch; a reactance of said antenna provides frequency tuning of said voltage controlled oscillator with said antenna switch in the said first state; an output of said phase lock loop provides information of said frequency tuning of said voltage controlled oscillator, said output of said phase lock loop connects to said microcontroller or said microprocessor; an output on said microcontroller or said microprocessor changes logic level dependent upon said information provided on said output of said phase lock loop; said output of said microcontroller or said microprocessor selects the state of said antenna switch between said first state and said second state; and said antenna is connected to said RFID decoder with said antenna switch in the said second state.