PROCEDURE FOR READING DATA STORED IN TRANSPONDER AND TRANSPONDER SYSTEM FOR PERFORMING PROCEDURE

摘要

PURPOSE: A procedure and a transponder is provided to demodulate signals of radio frequency question even when the distance between a transponder and a detector is long or even when interference frequency is existed within an action frequency. CONSTITUTION: A question device receives background noise on the purpose of detecting interference frequency contained in the background noise to read the data stored in a transponder. Coefficients about an adaptive filter(22) are tuned to restrain the interference frequency. A response signal from the transponder having overlapped background noise is received by the question device and routed via the adaptive filter restraining the interference frequency. Then, signals usable in the output of a filter are demodulated to read the stored data. A transponder system to perform the procedure includes a digital signal processor(20) calculating the coefficients about the adaptive filter according to the interference frequency and tunes the filter by restraining the interference frequencies in the radio frequency response signals received from the transponder delivering the overlapped background noise.