Procedure for reading the data stored in a transponder and a transponder system for the execution of the procedure

摘要

For reading the data stored in a transponder by means of an interrogation device, the interrogation device at first receives the background noise for the purpose of detecting interference frequencies present in this background noise. On the basis of the interference frequencies acquired, coefficients for an adaptive filter (22) are computed by means of which this filter may be tuned in such a way as to suppress the interference frequencies. The response signal from the transponder with the superimposed background noise is received by the interrogation device and routed through the adaptive filter (22) which acts to suppress the interference frequencies. The signal available at the output of the filter can then be demodulated (26) for the purpose of reading the data stored. The transponder system for the execution of the procedure comprises a digital signal processor (20) which computes coefficients for an adaptive filter (22) on the basis of the interference frequencies acquired, and tunes the filter in such a way that the interference frequencies within the RF response signal received from the transponder, carrying the superimposed background noise, are suppressed. The output signal from the adaptive filter may then be used for further processing. <IMAGE>