Rfid System Signal Processing And Dsp Implementation

RFID (Radio Frequency Identification) is an automatic identification technology that has been developed since 1990s. For the identification and the data exchange, it communicates by radio frequency with the host. RFID system has the particular contactless, anti-interference and environmental adaptability characters, so it becomes one of the most excellent automatic identification procedure that are applied in many fields. We introduce principium, configuration, characteristics and some relatively basic theory about RFID system, and analyze the key technologies and ISO/IEC15693 protocol. On the basis of ISO/IEC15693 we have studied as following: 1) The method of developing reading and writing space. Under analyzing the signal at receiving chain, the sub-carrier signal is demodulated and decoded by spectrum estimation but not diode demodulation. Methods of the classical spectrum estimation and the modern spectrum estimation are analyzed, simulated, compared. At last we elicit the direct digital decode algorithm at the frequency domain. 2) Under the situation collisions that multi-tags occupying a single channel and transmitting their data lead into at the same time, we use data check and anti-collision algorithms to resolve that problem. In order to resolve this problem, we must use multiple access protocols. Due to the data transmission characteristics between tags and reader, space division multiple access (SDMA), frequency division multiple access (FDMA) and code division multiple access (CDMA) are applied in a limited way in RFID system. Therefore, time division multiple (TDMA) has been generally accepted. According to TDMA, we have studied ALOHA protocol, Slot-ALOHA, Binary-tree Protocol. According to ISO/IEC15693 protocol, we analyze the anti-collision algorithm about this protocol. Based on the above study, the hardware and software design of a RFID system according to ISO/IEC15693 were completed. In this design, the DSP TMS320F2812 and the CPLD EPM3064 are used as core processor and logic control unit respectively. The RFID system communicates with the host by RS232 serial interface and net interface. The RFID system was debugged at Wind Guide Security Product Inc. It could identify the Phlips's radio frequency identification card, I-Code SL1, realize the basic functions of ISO/IEC15693.