METHOD AND DEMODULATOR FOR DEMODULATING AMPLITUDE-KEYED AND SHIFTED SIGNAL Russian patent published in 2003 - IPC

FIELD: electronic engineering. SUBSTANCE: method involves demodulation of voltage modulated by varying amplitude between low and high level of amplitude-modulated signal level used in contactless data transmission to chip card from card data reader/card data recorder wherein first mean value is shaped during initialization step from high voltage level and separated and saved voltage picked off divider so as to compare modulated voltage with mentioned first mean value and to determine transfer to low voltage level corresponding to starting value. During next demodulation step second mean value is shaped from low voltage level obtained and from high-voltage level for demodulating modulated voltage by comparing it with second mean value. EFFECT: enhanced reliability of recovering data signal transferred. 5 cl, 2 dwg