Radio-card communication system

Details Radio-card communication system Radio-card communication system

1995-03-17

1997-08-26

Tse, Young T.

Pulse or digital communications

Systems using alternating or pulsating current

Angle modulation

375332, 329306, G06K 100, H04L 2722

Patent

active

056617577

ABSTRACT:
To receive a response signal from a radio card, a card reader transmits a carrier (not modulated) to the radio card. In the radio card, a phase modulator phase-modulates the a sub-carrier with a response signal, thereby generating a PSK signal, and a phase modulator phase-modulates the carrier with the PSK signal, producing a PSK-PSK signal. The PSK-PSK signal is supplied to an antenna via a signal-extracting device. The antenna sends the PSK-PSK signal toward the card reader. In the card reader, a distributor distributes the PSK-PSK signal to a synchronous detector and an orthogonal detector. The detectors performs synchronous detection by using carriers which differ in phase by 90.degree.. Low-pass filters extract sub-carrier components from the outputs of the detectors. The sub-carrier components are delayed and detected by delay detectors and added together by an adder. The level of the output of the adder is determined by a data discriminator, whereby the card reader obtains the response signal transmitted from the radio card.

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patent: 4041391 (1977-08-01), Deerkoski
patent: 4213119 (1980-07-01), Ward et al.
patent: 4641374 (1987-02-01), Oyama
patent: 4792996 (1988-12-01), Oyama
patent: 5066957 (1991-11-01), Mizuno et al.
patent: 5204675 (1993-04-01), Sekine
patent: 5283780 (1994-02-01), Schuchman et al.
patent: 5432819 (1995-07-01), Mui
patent: 5533113 (1996-07-01), Ozawa et al.

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