Radio IC card system
First Claim
1. An IC card for use with a radio data transmitter/receiver device that transmits a first signal comprising a predetermined pattern and a second radio signal comprising predetermined carrier-modulated data from a transmitting antenna, the IC card comprising:
- a radio switching means, activated by the predetermined pattern in said first radio signal, comprising;
a receiving antenna for receiving said first radio signal;
a surface acoustic wave (SAW) matched filter for extracting said predetermined pattern from said received first radio signal;
an accumulation circuit for generating an output power accumulated from said SAW matched filter; and
a switching circuit, activated when said output power from said accumulation circuit exceeds a predetermined threshold value; and
a data communication unit for receiving said second radio signal from and transmitting a third radio signal comprising data to said transmitter/receiver device, for processing said data, and for transmitting a control signal to said radio switching means after terminating transmission or reception and processing of said data;
wherein said data communications unit is connected to a battery via said switching circuit for supplying power to said data communication unit in response to activation of said radio switching means.
1 Assignment
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Accused Products
Abstract
A radio IC card system includes an IC card and a toll collector. When an automobile with the IC card passes by a tollgate, the toll collector installed in the tollgate transmits a first radio signal which is spread modulated using a pseudorandom noise (PN) code from an antenna. The first radio signal is received by the antenna of the IC card and is transmitted to a surface acoustic wave (SAW) correlator. The SAW correlator extracts a PN code included in the received signal, and outputs a peak signal. An accumulation circuit accumulates the peak signal. A threshold discharger is activated to switch on a relay switch when the output voltage of the accumulation circuit exceeds a constant value. Thereby, the voltage of a battery is supplied to a data communication unit. Then, the identification code of the IC card and a record of tollgates by which the automobile has passed are transmitted via radio signal to the toll collector.
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Citations
4 Claims
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1. An IC card for use with a radio data transmitter/receiver device that transmits a first signal comprising a predetermined pattern and a second radio signal comprising predetermined carrier-modulated data from a transmitting antenna, the IC card comprising:
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a radio switching means, activated by the predetermined pattern in said first radio signal, comprising; a receiving antenna for receiving said first radio signal; a surface acoustic wave (SAW) matched filter for extracting said predetermined pattern from said received first radio signal; an accumulation circuit for generating an output power accumulated from said SAW matched filter; and a switching circuit, activated when said output power from said accumulation circuit exceeds a predetermined threshold value; and a data communication unit for receiving said second radio signal from and transmitting a third radio signal comprising data to said transmitter/receiver device, for processing said data, and for transmitting a control signal to said radio switching means after terminating transmission or reception and processing of said data; wherein said data communications unit is connected to a battery via said switching circuit for supplying power to said data communication unit in response to activation of said radio switching means. - View Dependent Claims (2)
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3. An IC card for use with a radio data transmitter/receiver device that transmits a first signal comprising a predetermined pattern and a second radio signal, the IC card comprising:
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a radio switching means, activated by the predetermined pattern in said first radio signal, comprising; a receiving antenna for receiving said first radio signal; a surface acoustic wave (SAW) matched filter for extracting said predetermined pattern from said received first radio signal; an accumulation circuit for generating an output power accumulated from said SAW matched filter; and a switching circuit, activated when said output power from said accumulation circuit exceeds a predetermined threshold value; a data communication unit for receiving said second radio signal from and transmitting a third radio signal comprising data to said transmitter/receiver device, for processing said data, and for transmitting a control signal to said radio switching means after terminating transmission or reception and processing of said data; wherein said data communications unit is connected to a battery via said switching circuit for supplying power to said data communication unit in response to activation of said radio switching means; switch-activation means for transmitting said first radio signal, said switch-activation means comprising; noise code generating means for generating a pseudorandom noise code; means for generating said first radio signal by modulating a carrier using said noise code; and an antenna for radiating said first radio signal; and transmitter/receiver means for transmitting a second radio signal comprising data and for receiving a third radio signal comprising data from a data communications unit activated by said first radio signal. - View Dependent Claims (4)
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Specification