Systems, methods, and computer program products for automatically adjusting the modulation index of a wireless smart device reader

• US 20080237345A1
• Filed: 06/20/2007
• Published: 10/02/2008
• Est. Priority Date: 03/30/2007
• Status: Abandoned Application

• Current Assignee: ViVOtech Incorporated
• Original Assignee: ViVOtech Incorporated
• Inventors: Johnson, William, Bousfield, Bruce M., Jiao, Xuejun, Moullette, Bruce L., Wiese, John E., Song, Steve
• Application Number:
  US11/820,795
• Publication Number:
  US 20080237345A1
• Time in Patent Office: Days
• US Class Current: 235/438
• CPC Class Codes: H04B 5/0031 for data transfer
• CPC Class Codes: H04B 5/0037 for power transfer
• CPC Class Codes: H04B 5/0056 for use in interrogation, identification or read/write systems record carriers G06K7/00, G06K19/00; for railways B61L3/12
• CPC Class Codes: H04B 5/02 using transceiver
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/77 for interrogation
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Systems, methods, and computer program products for automatically adjusting the modulation index of a wireless smart device reader are disclosed. According to one aspect, the subject matter described herein includes a method (performed at a wireless smart device reader) that includes receiving a signal from a wireless smart device. A parameter of the signal is determined. The method also includes determining at least one transmission parameter using the parameter of the signal. The transmission parameter(s) is applied to a transmitter of the wireless smart device reader in order to adjust the modulation index of the transmitter.

Claims

1. A method for automatically adjusting a modulation index of a wireless smart device reader, the method comprising:

at a wireless smart device reader;

receiving a signal from a wireless smart device;

determining a parameter of the signal;

determining at least one transmission parameter using the parameter of the signal; and

applying the at least one transmission parameter to a transmitter of the wireless smart device reader to adjust a modulation index of the transmitter.

2. The method of claim 1 wherein the parameter of the signal comprises an amplitude of the signal.

3. The method of claim 1 wherein the at least one transmission parameter comprises a radio transmission gain setting for the transmitter.

4. The method of claim 1 wherein determining at least one transmission parameter includes querying a database that maps the parameter to the at least one transmission parameter.

5. The method of claim 1 wherein determining the at least one transmission parameter includes calculating the at least one transmission parameter from a difference between the modulation index of the received signal and a desired modulation index.

6. The method of claim 1 wherein the wireless smart device comprises one of a contactless card, a contactless fob, and a mobile phone or a personal digital assistant (PDA) provisioned with a soft card.

7. The method of claim 1 wherein determining the parameter of the signal includes:

filtering the signal to obtain amplitude peak data from the signal; and

converting the amplitude peak data into digital data to be used to determine the at least one transmission parameter.

8. The method of claim 7 wherein filtering the signal includes filtering using a 13.56 MHz bandpass filter.

9. The method of claim 1 wherein the signal comprises a modulated signal that includes a modulated amplitude and an unmodulated amplitude, wherein the method further comprises calculating a modulation index for the transmitter using the unmodulated amplitude and the modulated amplitude, and the at least one transmission parameter is determined using the calculated modulation index.

10. The method of claim 9 wherein the modulation index is determined by calculating (a−

b)/(a+b), wherein a represents the unmodulated amplitude and b represents the modulated amplitude.

11. The method of claim 9 wherein the at least one transmission parameter comprises a transmission gain setting for the transmitter.

12. The method of claim 9 wherein the wireless smart device comprises one of a contactless card, a contactless fob, and a mobile phone or a personal digital assistant (PDA) provisioned with a soft card.

13. The method of claim 9 wherein the calculating step is performed only if the modulation index differs from a previously stored modulation index.

14. The method of claim 1 comprising continually receiving the signal and adjusting the at least one transmission parameter based on the parameter of the signal to control the value of the modulation index in a closed loop manner.

15. The method of claim 9 wherein the signal is filtered to determine each of the unmodulated amplitude and the modulated amplitude.

16. The method of claim 15 wherein the signal is filtered using a 13.56 MHz bandpass filter.

17. A wireless smart device reader for automatically adjusting a modulation index comprising:

a transceiver for receiving a signal from a wireless smart device; and

a processing unit for determining a parameter of the signal, determining at least one transmission parameter using the parameter of the signal, and applying the at least one transmission parameter to the transceiver to adjust a modulation index of the transceiver.

18. The wireless smart device reader of claim 17 wherein the parameter of the signal comprises an amplitude of the signal.

19. The wireless smart device reader of claim 17 wherein the at least one transmission parameter comprises a radio transmission gain setting for the transceiver.

20. The wireless smart device reader of claim 17 wherein the wireless smart device is adapted to query a database that maps the parameter in the signal to the at least one transmission parameter.

21. The wireless smart device reader of claim 17 wherein the wireless smart device reader is adapted to calculate the at least one transmission parameter from a difference between the modulation index of the received signal and a desired modulation index.

22. The wireless smart device reader of claim 17 wherein the wireless smart device comprises one of a contactless card, a contactless fob, and a mobile phone or a personal digital assistant (PDA) provisioned with a soft card.

23. The wireless smart device reader of claim 17 wherein the wireless smart device is adapted to:

filter the signal to obtain amplitude peak data from the signal; and

convert the amplitude peak data into digital data to be used to determine the at least one transmission parameter.

24. The wireless smart device reader of claim 23 wherein the wireless smart device is further adapted to filter the signal using a 13.56 MHz bandpass filter.

25. The wireless smart device reader of claim 17 wherein the signal comprises a modulated signal that includes a modulated amplitude and an unmodulated amplitude, wherein the processing unit is adapted to calculate a modulation index using the unmodulated amplitude and the modulated amplitude, and the processing unit is adapted to determine the at least one transmission parameter using the calculated modulation index.

26. The wireless smart device reader of claim 25 wherein the processing unit is adapted to determine the modulation index by calculating (a−

b)/(a+b), wherein a represents the unmodulated amplitude and b represents the modulated amplitude.

27. The wireless smart device reader of claim 25 wherein the at least one transmission parameter comprises a transmission gain setting for the transceiver.

28. The wireless smart device reader of claim 25 wherein the wireless smart device comprises one of a contactless card, a contactless fob, and a mobile phone or a personal digital assistant (PDA) provisioned with a soft card.

29. The wireless smart device reader of claim 17 wherein the processing unit continually updates the at least one transmission parameter based on the parameter of the signal to control the value of the modulation index in a closed loop manner.

30. The wireless smart device reader of claim 25 wherein the signal is filtered to determine each of the unmodulated amplitude and the modulated amplitude.

31. The wireless smart device reader of claim 30 wherein the signal is filtered using a 13.56 MHz bandpass filter.

32. A computer program product comprising computer executable instructions embodied in a computer readable medium for performing steps comprising:

at a wireless smart device reader;

receiving a signal from a wireless smart device;

determining a parameter of the signal;

determining at least one transmission parameter using the parameter of the signal; and

applying the at least one transmission parameter to a transmitter of the wireless smart device reader to adjust a modulation index of the transmitter.