Measurement and Reporting of Received Signal Strength in NFC-Enabled Devices

• US 20120329389A1
• Filed: 06/27/2011
• Published: 12/27/2012
• Est. Priority Date: 06/27/2011
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: ROYSTON, Philip Stewart, COX, David Grant
• Granted Patent: US 9,042,814 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 5/73 for taking measurements, e.g. using sensing coils
• CPC Class Codes: H04B 5/77 for interrogation
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

An NFC-enabled device including tag emulation circuitry and reader emulation circuitry operates so as to provide a signal strength meter function. The signal strength meter function, in tag emulation mode, measures and reports on how well the tag is coupled to a third party reader field. In reader emulation mode, the signal strength meter function measures and reports how well the reader of the NFC-enabled device couples to a tag that is being read. One exemplary method includes detecting an NFC reader field, operating reader receiver circuitry at the NFC-enabled device so as to at least determine the strength of a signal received from the reader field, generating information representative of the determined strength of the signal received from the reader field at a first time, and performing one or more predetermined actions based at least in part on the one or more signals representative of the determined strength. Predetermined actions may include generating visual, audio, and/or other indications of the received signal strength.

Claims

1. A method of operating an NFC-enabled device, comprising:

detecting, at the NFC-enabled device, an NFC reader field, based on a current induced within an antenna of the NFC-enabled device;

operating reader receiver circuitry at the NFC-enabled device so as to at least determine a strength of a signal received from the NFC reader field;

generating information representative of the determined strength of the signal received from the reader field at a first time; and

performing one or more predetermined actions based on the information.

2. The method of claim 1, wherein performing one or more predetermined actions comprises:

generating a user perceivable output representative of the determined signal strength.

3. The method of claim 2, wherein the user perceivable output comprises a visual display.

4. The method of claim 3, wherein the visual display is a bar graph.

5. The method of claim 2, wherein the user perceivable output comprises audio.

6. The method of claim 1, wherein performing one or more predetermined actions comprises:

transmitting, from the NFC-enabled device, one or more commands to a device physically remote from the NFC-enabled device;

wherein the one or more commands direct the remote device to generate a user perceivable output representative of the determined signal strength.

7. The method of claim 6, wherein the user perceivable output is selected from the group consisting of visual, audio, electrical and mechanical outputs.

8. The method of claim 1, further comprising:

waking at least a portion of the NFC-enabled device from a power saving state subsequent to detecting the NFC reader field.

9. The method of claim 1, further comprising:

determining that the received signal strength is below a threshold value and generating a user perceivable output indicative of the received strength being below the threshold value.

10. The method of claim 1, further comprising:

generating information representative of the determined strength of the signal received from the NFC reader field at each of one or more times subsequent to the first time; and

storing the information associated at least one of the one or more times subsequent to the first time.

11. A method of operating an NFC-enabled computational platform, comprising:

detecting a current induced by a NFC reader field in an NFC antenna of the NFC-enabled computational platform, wherein the current represents a measure of coupling between the NFC reader field and a tag;

operating a reader receiver to a measure of the current in the NFC antenna and to receive in-phase (I) and quadrature (Q) versions of the signal in the antenna;

generating one or more signals indicative of the coupling between the NFC reader field and the tag based on levels of the I and Q versions of the signal; and

producing a user perceivable output based on the one or more signals.

12. The method of claim 11, wherein the user perceivable output is a visual output.

13. The method of claim 11, wherein the user perceivable output is an audio output.

14. The method of claim 11, further comprising:

transmitting one or more commands to a device physically remote from the NFC-enabled device;

wherein the remote device is operable to produce a user perceivable output.

15. The method of claim 14, wherein the device physically remote from the NFC-enabled device is a earphone.

16. An NFC-enabled device, comprising:

a plurality of device specific resources disposed within the NFC-enabled device;

an NFC antenna;

an NFC tag functional block coupled to at least one of the plurality of device specific resources and to the NFC antenna, the NFC tag functional block including a reader receiver; and

a signal strength meter functional block coupled to the reader receiver;

wherein the reader receiver is operable to recover in-phase(I) and quadrature (Q) versions of signals induced in the NFC antenna, and wherein the signal strength meter functional block is operable to produce an information signal based on levels of the I and Q versions.

17. The NFC-enabled device of claim 16, further comprising:

an NFC reader functional block coupled to at least one of the plurality of device specific resources.

18. The NFC-enabled device of claim 16, further comprising:

a visual signal strength meter indicator coupled to the signal strength meter functional block.

19. The NFC-enabled device of claim 16, further comprising:

an audio signal strength meter indicator coupled to the signal strength meter functional block.

20. The NFC-enabled device of claim 16, wherein at least one of the device specific resources is operable to transmit the information signal a receiver that is physically remote from the NFC-enabled device.

21. A method of operating an NFC-enabled device in tag emulation mode, the NFC-enabled device having a tag antenna and a tag antenna shunt regulator coupled thereto, the method comprising:

determining a coupling strength between the tag antenna and a reader field from a peak voltage across the tag antenna when the peak voltage is below a shunt regulator threshold voltage; and

determining the coupling strength from the current in the tag antenna when the tag shunt regulator is shunting.