Modulation, demodulation and antenna coupling circuits used in I

Details Modulation, demodulation and antenna coupling circuits used in I Modulation, demodulation and antenna coupling circuits used in I

1995-05-24

1997-09-23

Bocure, Tesfaldet

Pulse or digital communications

Receivers

Angle modulation

375364, 329309, H04L 2714, H04L 2716, H04L 2722

Patent

active

056712545

ABSTRACT:
A modulator used in an IC card reader/writer includes a phase variation detector for detecting a varying point of the phase of a modulated signal, a signal processing circuit for modifying the modulated signal for a half period at the phase varying point to have a frequency and amplitude twice those of the modulated signal, a first Miller integrator for integrating the modified signal to produce a triangular wave signal, and a second Miller integrator for integrating the triangular wave signal to produce a sinusoidal wave signal having a continuous phase. A demodulator used in the reader/writer includes a sync control circuit which controls a carrier sync signal generation circuit thereby to control the phase of a carrier sync signal in response to the discrimination as to whether the carrier sync signal is in lead-phase or lag-phase relative to the signal modulated based on binary phase shift keying (BPSK). A control data signal and non-modulated carrier wave sent from the reader/writer to the IC card are converted into power for use by the IC card.

REFERENCES:
patent: 4311964 (1982-01-01), Boykin
patent: 4724427 (1988-02-01), Carroll
patent: 4744094 (1988-05-01), McCarren
patent: 5218343 (1993-06-01), Stobbe et al.

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