System and method for interrogation radio-frequency identification

• US 20090045913A1
• Filed: 08/16/2007
• Published: 02/19/2009
• Est. Priority Date: 08/16/2007
• Status: Active Grant

• Current Assignee: Farpointe Data Incorporated (dormakaba Holding AG)
• Original Assignee: Farpointe Data Incorporated (dormakaba Holding AG)
• Inventors: Lindley, Scott E., Nelson, Christopher J.
• Granted Patent: US 8,624,710 B2
• Time in Patent Office: Days
• US Class Current: 340/5.660
• 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
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator

Abstract

A system and method for communicating with contactless IC cards of multiple protocols and power levels includes generating a first alternating magnetic field with an interrogator for energizing a proximate IC card and receiving a data transmission from the IC card. A processor of the interrogator is configured to decode the received data transmission. The interrogator then generates a second alternating magnetic field having a different magnetic field strength than the first alternating magnetic field when failing to decode the data transmission being received from the IC card. The processor then attempts to decode a data transmission received from the IC card in response to the second alternating magnetic field.

Claims

1. A method for communicating with contactless IC cards, the method comprising:

generating a first alternating magnetic field for energizing a proximate IC card, wherein the first alternating magnetic field corresponds to a first output power level;

receiving a data transmission from a proximate IC card;

attempting to decode the data transmission being received from the IC card;

generating a second alternating magnetic field having a different magnetic field strength than the first alternating magnetic field when failing to decode the data transmission being received from the IC card, wherein the second alternating magnetic field corresponds to a second output power level; and

again attempting to decode a data transmission being received from the IC card.

2. The method of claim 1, wherein the first alternating magnetic field is stronger than the second alternating magnetic field.

3. The method of claim 1, wherein the first alternating magnetic field is weaker than the second alternating magnetic field.

4. The method of claim 1, further comprising:

repeatedly alternating generation of the first alternating magnetic field and the second alternating magnetic field; and

attempting to decode data transmissions received from one or more IC cards following generation of each alternating magnetic field.

5. The method of claim 4, further comprising:

computing the number of decoded data transmissions following the first alternating magnetic fields; and

computing the number of data transmission decoded following the second alternating magnetic fields.

6. The method of claim 5, further comprising:

adjusting duration of the first output power level and duration of the second output power level as a function of one of (i) the number of decoded data transmissions following the first alternating magnetic fields and (ii) the number of decoded data transmission following the second alternating magnetic fields.

7. A method for communicating with contactless IC cards, the method comprising:

generating a first alternating magnetic field for energizing a proximate IC card;

transmitting an IC card polling signal;

receiving a data transmission from a proximate IC card;

determining whether or not the data transmission is being received in response to the polling signal;

attempting to decode the data transmission being received when the data transmission is being received in response to the polling signal; and

generating a second alternating magnetic field when failing to decode the data transmission being received, the second alternating magnetic field having different magnetic field strength than the first alternating magnetic field.

8. The method of claim 7, further comprising:

attempting to decode a data transmission being received from the proximate IC card following generation of the second alternating magnetic field.

9. The method of claim 8, wherein the first alternating magnetic field is stronger than the second alternating magnetic field.

10. The method of claim 8, wherein the first alternating magnetic field is weaker than the second alternating magnetic field.

11. The method of claim 8, wherein determining whether or not the data transmission is being received in response to the polling signal comprises determining whether the data transmission being received before or after expiration of a predetermined time period following transmission of the polling signal.

12. The method of claim 11, further comprising:

storing the received data transmission in a memory and decoding the stored data transmission when the data transmission is not being received in response to the polling signal.

13. The method of claim 12, wherein decoding the data transmission stored in the memory includes determining format of the stored data transmission includes:

determining whether the data transmission includes one or more start bits;

determining whether the data transmission includes one or more parity bits; and

determining whether the data transmission includes one or more cyclic redundancy check (CRC) bits.

14. A system for communicating with contactless IC cards, the system comprising:

a transmitter configured to generate a first alternating magnetic field for exciting a proximate IC card, wherein the first alternating magnetic field corresponds to a first output power level;

a receiver configured to detect a data transmission from a proximate IC card; and

a processor configured to

attempt to decode in real-time the detected data transmission, and

generate a control signal when failing to decode the data transmission,

wherein in response to the control signal the transmitter is configured to generate a second alternating magnetic field having a different magnetic field strength than the first alternating magnetic field, wherein the second alternating magnetic field corresponds to a second output power level.

15. The system of claim 14, wherein the first alternating magnetic field is stronger than the second alternating magnetic field.

16. The system of claim 14, wherein the first alternating magnetic field is weaker than the second alternating magnetic field.

17. The system of claim 14, wherein the processor is configured to

repeatedly alternate generation a control signal thereby alternating generation of the first alternating magnetic field and the second alternating magnetic field;

and

attempt to decode data transmissions received from one or more IC cards following generation of each alternating magnetic field.

18. The system of claim 17, wherein the processor is configured to

compute the number of decoded data transmissions following the first alternating magnetic fields;

and

compute the number of data transmission decoded following the second alternating magnetic fields.

19. The system of claim 18, wherein the processor is configured to:

adjust duration of the first output power level and duration of the second output power level as a function of one of (i) the number of decoded data transmissions following the first alternating magnetic fields and (ii) the number of decoded data transmission following the second alternating magnetic fields.

20. Logic encoded in one or more tangible media for execution and when executed operable to:

select a first output power level of a contactless IC card interrogator;

select a second output power level of the IC card interrogator when the IC card interrogator fails to decode one or more data transmissions from a proximate IC card; and

select a duration of application of the first output power level and a duration of application of the second output power level.