Measurement and reporting of received signal strength in NFC enabled devices
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.
1. An NFC-enabled mobile device, comprising:
a field detector circuit configured to detect an NFC reader field based on a current induced within an antenna of the NFC-enabled mobile device;
a receiver circuit configured to wake from a powered-down state in response to detection of the NFC reader field by the field detector circuit, the receiver circuit further configured to generate in-phase (I) and quadrature (Q) components of an incoming signal received from the NFC reader field;
first circuitry configured to determine a strength of the incoming signal received from the NFC reader field based on the I and Q components generated;
second circuitry configured to generate information representative of the determined strength at a first time; and
third circuitry configured to generate a first user perceivable output representative of the determined strength of the incoming signal, the first user perceivable output configured to direct a user to improve the strength of the incoming signal.
2. The NFC-enabled mobile device of claim 1 , wherein the first user perceivable output comprises a visual display.
3. The NFC-enabled mobile device of claim 2 , wherein the visual display is configured to display a bar graph.
4. The NFC-enabled mobile device of claim 2 , further comprising a housing inside of which the field detector circuit and the reader receiver circuit are disposed.
5. The NFC-enabled mobile device of claim 4 , wherein the third circuitry is mounted within the housing such that the visual display is observable from outside of the housing.
6. The NFC-enabled mobile device of claim 4 , wherein the third circuitry is mounted on the housing such that the visual display is observable from outside of the housing.
7. The NFC-enabled mobile device of claim 4 , wherein the first circuitry and the second circuitry are disposed within the housing.
8. The NFC-enabled mobile device of claim 2 , wherein the visual display comprises LEDs.
9. The NFC-enabled mobile device of claim 1 , further comprising a printed circuit board disposed within the housing.
10. An NFC-enabled computational platform, comprising:
a first circuit configured to detect a current induced by an 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;
a reader receiver configured to a measure of the current in the NFC antenna and to receive in-phase (I) and quadrature (Q) versions of a signal in the NFC antenna;
a second circuit configured to generate a signal indicative of the coupling between the NFC reader field and the tag based on levels of the I and Q components of the signal; and
a third circuit configured to produce a user perceivable output based on the signal.
11. The NFC-enabled computational platform of claim 10 , wherein the third circuit is coupled to a visual display.
12. The NFC-enabled computational platform of claim 11 , wherein the visual display is configured to display a bar graph.
13. The NFC-enabled computational platform of claim 10 , wherein the user perceivable output is an audio output.
14. The NFC-enabled computational platform of claim 10 , further comprising:
a fourth circuit configured to wirelessly transmit a command to a device that is physically remote from the NFC-enabled computational platform;
wherein the physically remote device is configured to produce a user perceivable output.
15. The NFC-enabled computational platform of claim 14 , wherein the physically remote device comprises an earphone.
16. The NFC-enabled computational platform of claim 10 , further comprising a housing inside of which the first circuit and the reader receiver circuit are disposed.
17. The NFC-enabled computational platform of claim 16 , wherein the third circuit is mounted within the housing such that the visual display is observable from outside of the housing.
18. The NFC-enabled computational platform of claim 16 , wherein the third circuit is mounted on the housing such that the visual display is observable from outside of the housing.
19. An NFC-enabled mobile device, comprising:
a field detector circuit configured to detect an NFC reader field based on a current induced within an antenna of the NFC-enabled mobile device;
a receiver circuit configured to wake from a powered-down state in response to detection of the NFC reader field by the field detector, the receiver circuit further configured to generate in-phase (I) and quadrature (Q) components of an incoming signal received from the NFC reader field;
first circuitry configured to determine a strength of the incoming signal received from the NFC reader field based on the I and Q components generated;
second circuitry configured to generate information representative of the determined strength at a first time; and
third circuitry configured to generate a first user perceivable output representative of the determined signal strength, the first user perceivable output configured to direct a user to improve the strength of the signal received;
wherein the field detector includes a shunt regulator.