In conventional radio frequency identification (RFID) technology, an RFID tag responds to a signal from an RFID reader by transmitting a response signal in which the RFID tag's binary identification number is encoded. Because most RFID tags are passive (they operate solely on the power harvested from the received signal from the RFID reader), low operational power is a high priority. Accordingly, most RFID tags use a low clock speed internally, since increased clock speed contributes to increased power consumption. Further, to keep the circuitry simple, many conventional RFID tags also use a simple frequency shift key (FSK) modulation technique using two frequencies, i.e., two different frequencies are alternately modulated onto the carrier wave, with one frequency representing a binary ‘1’ and the other frequency representing a binary ‘0’. While this scheme is simple, inexpensive, and consumes little power, the data rate is limited to the clock rate, which is typically no more than 640 kbits per second, and is frequently much less than that.
USPTO Backgrounds
USPTO Backgrounds