A radio frequency identification (RFID) tag device having a pulse position
modulation (PPM) decoder circuit which calculates a relative frequency
relationship between an internal oscillator of the RFID tag device and an
external PPM source such as a RFID tag reader. The PPM decoder circuit is
calibrated to the difference between the external PPM frequency source
(i.e., RFID tag reader) and the internal clock-oscillator of the RFID tag
device, which is performed in a single measurement during one calibration
symbol period.
