Base station for a contactless interrogation system comprising a phase locked and voltage controlled oscillator
First Claim
1. 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.
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Abstract
A base station (13) for a contactless interrogation system includes an oscillating device (23) supplying a control signal having a frequency which is adjustable via adjusting circuits (21, 22), a circuits (24) for controlling an antenna connected to the base station (13) for transmitting information, decoding circuits (25, 26, 27) for decoding the information picked up by the antenna. The oscillating device (23) is a voltage controlled oscillator which is phase locked by the adjusting circuits (21, 22), so that the control signal frequency is determined by the base station (13) and is adapted to the antenna. The sensitivity of a contactless interrogation system comprising the base station (13) of the present invention is improved, its structure is simpler and its different components can be integrated in a same chip.
48 Citations
9 Claims
- 1. 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.
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9. A base station connected to antenna means for transmitting and/or receiving data 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 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 and is continuously tuned to the resonant frequency of said antenna means by said adjusting means in a phase locked loop, wherein said decoding means comprise a sampler, a pass-band filter and a decision circuit, and wherein said sampler is synchronised by a clock signal originating from said voltage controlled oscillator.
Specification