Signal recovering for UHF RFID by matching algorithm

The proposed scheme used digital circuit design to improve the performance of RFID readers and increase the readable distance of tags from the reader in indoor environments. Basically, the transmitted data are subject to vagaries and influences of media or channels through which the data has to pass, including the air interface, amplifiers, mixers and filters, etc., in RFID systems. There are two familiar approaches in common use to process the received baseband RFID signals captured from tags. One approach adopts the DSP techniques, and the other uses amplifiers and hysteresis comparators. The latter is usually simpler and less expensive, but it is unable to tolerate the noise and DC offset; the former is the opposite, but more expensive. The proposed scheme is mainly designed to eliminate the following three concerned negative effects - AWGN, DC offset and circuit distortion. Two simulation results for severe distortion cases, one caused by RC decay and the other by severe bias drifts and unstable amplitude, are chosen from many experiments to demonstrate and explain the advantages of our proposed scheme.