Patent ID: 8724761

Claim:
A symbol synchronization apparatus of a passive radio frequency identification (RFID) reader that transmits energy to a passive RFID tag, the apparatus comprising: an edge clock detector configured to generate edge clocks by detecting phase inversion positions of a received signal; a preamble detector configured to determine a section of the received signal is a preamble section of the received signal by analyzing the generation times of the edge clocks, wherein the preamble section includes a first portion that is distorted by the passive RFID reader′s transmitted energy, and a second binary pattern portion; a symbol decision time extractor configured to extract a symbol decision time by averaging distances between the edge clocks consecutively generated in the second binary pattern portion of the preamble section and not using the first portion of the preamble section when the preamble section is detected; and a symbol decider configured to decide a symbol by analyzing magnitudes of the received signal when the time reaches the symbol decision time, wherein the received signal comprises a symbol 0 matched filtering signal and a symbol 1 matched filtering signal, and wherein the symbol decider decides a symbol by comparing the magnitudes of the symbol 0 matched filtering signal and the symbol 1 matched filtering signal contained in the received signal.