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

• US 6,215,437 B1
• Filed: 08/25/1999
• Issued: 04/10/2001
• Est. Priority Date: 10/13/1998
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Schürmann, Josef H., Hagl, Andreas, Aslanidis, Konstantin O.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/382,520
• Time in Patent Office: 594 Days
• Field of Search: 342/42, 342/44, 342/51, 342/159, 342/162
• US Class Current: 342/42
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

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 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 which acts to suppress the interference frequencies. The signal available at the output of the filter can then be demodulated for the purpose of reading the data stored. The transponder system for the execution of the procedure comprises a digital signal processor which computes coefficients for an adaptive filter 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.

Claims

1. A method of remote communication in a noisy environment, within a predetermined frequency band, between an interrogator and a transponder wherein an interrogator transmits an interrogation signal and the transponder responds with data, stored therein, modulating a transponder response signal, comprising:

receiving background noise, having frequency components, within said predetermined frequency band during a time when neither said interrogation signal nor said transponder response signal are being transmitted or received;

converting said background noise into a digital signal;

identifying said frequency components of said background noise which have an amplitude exceeding a predetermined threshold;

computing coefficients of an adaptive filter, having a passband characteristic, in dependence upon said identified frequency components such that said passband characteristic suppresses said identified frequency components;

transmitting said interrogation signal;

receiving said transponder response signal and superimposed background noise;

converting said transponder response signal and said superimposed noise into a digital signal;

routing said digital signal through said adaptive filter; and

demodulating the output of said adaptive filter and yielding said data stored therein.

2. The method according to claim 1, wherein said data within said transponder response signal is FSK modulated and said transponder response signal comprises a sideband with two sideband frequencies.

3. The method according to claim 2 and further comprising:

determining whether said identified frequency components interfere with one of said two sideband frequencies; and

demodulates said transponder response signal using amplitude demodulation in dependence upon said determination being positive and using FSK demodulation in dependence upon said determination being negative.

4. The method according to claim 1 wherein said reception of said background noise is performed subsequent to reception of said transponder response signal and said superimposed background noise.

5. A system of remote communication robust in a noisy environment, within a predetermined frequency band, between an interrogator and a transponder wherein an interrogator transmits an interrogation signal and the transponder responds with data, stored therein, modulating a transponder response signal, said interrogator comprising:

a receiver for receiving background noise, having frequency components, within said predetermined frequency band during a time when neither said interrogation signal nor said transponder response signal are being transmitted or received and for receiving said transponder response signal and superimposed background noise during a time when said transponder response signal is transmitted;

an A/D converter for converting said background noise and said transponder response signal and said superimposed background noise into digital signal;

a detector for identifying said frequency components of said background noise which have an amplitude exceeding a predetermined threshold;

a processor for computing coefficients of an adaptive filter, having a passband characteristic, in dependence upon said identified frequency components such that said passband characteristic suppresses said identified frequency components;

a transmitter for transmitting said interrogation signal;

an adaptive filter for filtering said digital signals;

a demodulator for demodulating the output of said adaptive filter and yielding said data stored therein.

6. The system according to claim 5 wherein the adaptive filter and demodulator are embodied as software modules which are processed by the processor for the purpose of achieving the desired function in each case.

7. The system according to claim 5 wherein said adaptive filter is integrated into the processor.