DATA CARRIER

PURPOSE:To demodulate the duty ratio of an original signal accurately regardless of a distance between a data carrier and a read/write head by rectifying a voltage obtained at a resonance circuit, detecting a mean voltage, dividing the voltage and using the divided voltage as a reference voltage of...

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Bibliographic Details
Main Author HIRAO IICHI
Format Patent
LanguageEnglish
Published 15.03.1991
Subjects
ELECTRIC COMMUNICATION TECHNIQUE
ELECTRICITY
TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION
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Summary:PURPOSE:To demodulate the duty ratio of an original signal accurately regardless of a distance between a data carrier and a read/write head by rectifying a voltage obtained at a resonance circuit, detecting a mean voltage, dividing the voltage and using the divided voltage as a reference voltage of a comparator. CONSTITUTION:A write/read-out control unit interrupts a transmission data SD at a prescribed period T by using a carrier with a prescribed frequency, and sends a signal to a data carrier by changing the duty ratio. A received voltage V0 corresponding to the distance between a data carrier and a read/ write head is obtained by a capacitor C3 of a mean voltage detection circuit 11 and divided by a voltage division circuit comprising a diode D3 and resistors R2, R3 and supplied as a reference voltage as the comparison quantity. Thus, the pulse width of a waveform shaping circuit 12 is hardly affected with the fluctuation of the detected voltage and stable waveform shaping is attained.
Bibliography:Application Number: JP19890197673