PURPOSE: An RFID reader for reducing communication time with an RFID tag is provided to improve tag recognition speed by reducing communication time for detecting an empty slot or the collision of reception signal by generating error type signals according to the detection of preamble. CONSTITUTION: A digital demodulator(345) of a controller generates integrated digital signal according to digital Q signal and digital I signal of ADCs(Analog to Digital Converters). A decoder of the controller determines binary data of the integrated digital signal inputted from the digital demodulator. The decoder detects a signal level of the integrated digital signal. The decoder detects the preamble of the binary data.
