Patent ID: 6272320
Filing Date: 2001-08-07
Classification: G06K

Abstract:
A base station connected between a microprocessor and antenna means for transmitting and/or receiving data signals for a contactless interrogation system, said base station comprising an oscillating device supplying a control signal to means for controlling antenna means for transmitting data, said control signal having a carrier frequency which is adjustable via adjusting means, means for decoding the data signals for a microprocessor connected to said base station, said data signals being picked up by said antenna means from received signals, wherein said oscillating device comprises a voltage controlled oscillator which is phase locked by said adjusting means, so that the carrier frequency of said control signal is determined solely by said base station independently of said microprocessor and is continuously tuned to the resonant frequency of said antenna means by said adjusting means in a phase locked loop so that the sensitivity of said base station connected to antenna means is increased.