Research On Contactless IC Card Reader With A Carrier Frequency Of 13.56MHz

Contactless IC card is developed by the technology of radio frequency. It solvedthe non-power and untouched puzzle by using radio frequency technology forcommunication.ISO/IEC14443 TYPEB standard is one of the communication standard protocolsfor Contactless IC card. The frequency of the RF operating field is 13.56 MHz. Thebit rate for the transmission is 106 kbit/s. Communication from reader to card usesthe modulation principle of ASK 10% of the RF operating field. Communicationfrom card to reader uses the modulation principle of BPSK with 847.5 kHz frequencyof subcarrier. The launching chunnel contains power amplification,tone and tuned circuit.A receiving module for card reader contains amplifier,demodulator anddecoding etc. The detection circuit implemented envelope detection when receivingthe signal from antenna. Tuning amplification circuit amplified the signal weexpected. It needed bit synchronization processing when the local crystal oscillatorsampling data. Here we took the method of software demodulation. After detectingthe signal MCU entered into interruption. The test signals controlled the JFET andgot the dispersion of phase relative to the original signal. The MCU processed thecorresponding result and locked phase. This processed signal was sent to MCU inputport for decoding. This paper demonstrates the circuits design a new method to design RF module ofcontactless IC card reader presented by using PIC microprocessor. Decoder wererealized mainly by individual element and software instead of special hardware ASIC.It has high performance of reliability. And it is less expensive than all of former RFmodules.