data transmission between a read / write device and a free smart card

摘要

The I.C. card (1) has antenna units (3,4), input unit (5) and a processing chip (2). The first antenna unit transmits the alternating voltage supply and receives the data modulated on the alternating voltage. The second antenna unit only reads the contents of the memory of the card (pulse-width modulation used). The alternating voltage is not regular and the different periods of switching over are used in the binary coding process.