Measurement and reporting of received signal strength in NFC-enabled devices

• US 9,042,814 B2
• Filed: 06/27/2011
• Issued: 05/26/2015
• 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
• Primary Examiner(s): HSIEH, PING Y
• Application Number:
  US13/169,609
• Publication Number:
  US 20120329389A1
• Time in Patent Office: 1,429 Days
• Field of Search: 455/41.1, 455/41.2, 455/41.3, 455/67.11, 455/67.14, 455/67.16, 455/67.7
• 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, by a field detector circuit of the NFC-enabled device, an NFC reader field based on a current induced within an antenna of the NFC-enabled device;

waking, in response to detecting the NFC reader field by the field detector circuit, a powered-down receiver circuit of the NFC-enabled device;

generating by the receiver circuit, after waking the powered-down receiver circuit, in-phase (I) and quadrature (Q) components of an incoming signal received from the NFC reader field;

determining a strength of the incoming signal received from the NFC reader field based on the I and Q components generated by the receiver circuit;

generating, at the NFC-enabled device, information representative of the determined strength at a first time; and

generating a first user perceivable output representative of the determined signal strength, the first user perceivable output configured to direct a user to spatially orient the NFC-enabled device to improve the strength of the signal received.

2. The method of claim 1, wherein the first user perceivable output comprises a visual display.

3. The method of claim 2, wherein the visual display comprises a bar graph.

4. The method of claim 1, wherein the first user perceivable output comprises audio.

5. The method of claim 1, further comprising:

generating a second user perceivable output by transmitting, from the NFC-enabled device, a command to a device physically remote from the NFC-enabled device;

wherein the command directs the device physically remote from the NFC-enabled device to provide the second user perceivable output representative of the determined signal strength and configured to direct the user to spatially orient the NFC-enabled device to improve the strength of the signal received.

6. The method of claim 5, wherein the second user perceivable output is selected from the group consisting of visual, audio, electrical and mechanical outputs.

7. The method of claim 1, further comprising:

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

8. The method of claim 1, further comprising:

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

storing the information associated with the second time.

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

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

powering-up, after detecting by the field detector circuit the current induced by the NFC reader field, a reader receiver circuit;

operating the reader receiver circuit, after powering-up, to receive a first signal and produce in-phase (I) and quadrature (Q) components of the first signal;

generating a second signal indicative of the strength of coupling between the NFC reader field and the tag based on levels of the I and Q components of the first signal, at a first time; and

producing a first user perceivable output based on the second signal indicative of the strength of coupling between the NFC reader field and the tag, the first user perceivable output configured to direct spatially orienting the NFC-enabled computational platform to improve the current induced in the NFC antenna by the NFC reader field.

10. The method of claim 9, wherein the first user perceivable output is a visual output.

11. The method of claim 9, wherein the first user perceivable output is an audio output.

12. The method of claim 9, further comprising:

transmitting a command to a device physically remote from the NFC-enabled computational platform;

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

13. The method of claim 12, wherein the device physically remote from the NFC-enabled device is an earphone.

14. An NFC-enabled device, comprising:

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

an NFC tag functional block coupled to at least one of the plurality of device specific resources, the NFC tag functional block including a field detector circuit configured to detect the presence of a reader field, and a reader receiver configured to wake from a power-saving state in response to a signal from the field detector circuit; and

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

wherein the reader receiver is further configured to recover in-phase (I) and quadrature (Q) components of signals induced in an NFC antenna, and

wherein the signal strength meter functional block is configured to produce an information signal based on levels of the I and Q components, at a first time, the information signal configured to direct a user to spatially orient the NFC-enabled device to improve a received signal strength.

15. The NFC-enabled device of claim 14, further comprising:

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

16. The NFC-enabled device of claim 14, further comprising:

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

17. The NFC-enabled device of claim 14, further comprising:

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

18. The NFC-enabled device of claim 14, wherein at least one of the plurality of device specific resources is configured to transmit the information signal to a receiver that is physically remote from the NFC-enabled device.