PEAK TRACK DATA RECOVERY DEMODULATOR
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-29
The problem relates generally to detecting data in an electronic reader interface, received from a contact less smart card or tag transponder, in which the reader supplies power to the contact less card or transponder via a radio frequency transmit loop antenna. The same transmit antenna is also used to receive a back-scattered signal from the smart card or tag device which is performed with an admittance load switching device inside the card/tag circuit. The problem arises in that the received data signal developed at the transmitter coil is very small in comparison with the radio frequency transmit signal requiring high carrier rejection filtering prior to signal detection. The solution proposed is a peak track demodulator capable of detecting low-level signals in a large signal environment such as card/tag reader.