Near-field RF communicators having a low-energy pre-polling process

1. A method of operating a near-field radio frequency (RF) communicator, comprising:

transmitting an RF signal;

comparing at least one measure of in-phase and quadrature-phase components of a signal in an inductive coupler that is disposed in the near-field RF communicator with at least one stored value; and

determining whether to initiate polling for another near-field RF communicator based on the comparison;

wherein transmitting, comparing and determining, together, require less time than polling for the other near-field RF communicator.

2. The method of claim 1 , further comprising:

storing at least one value based on the at least one measure of the in-phase and quadrature-phase components in a memory to provide at least one stored value for a subsequent comparison.

3. The method of claim 2 , wherein the at least one stored value comprises a first stored value indicating the in-phase component and a second stored value indicating the quadrature-phase component.

4. The method of claim 3 , further comprising:

determining a first difference between the first indication and the first stored value; and

determining a second difference between the second indication and the second stored value.

5. The method of claim 4 , further comprising:

comparing the first difference with a first threshold value;

comparing the second difference with a second threshold value; and

initiating the polling for the other near-field RF communicator in the event that the first difference exceeds the first threshold value or the second difference exceeds the second threshold value.

6. The method of claim 4 , further comprising:

determining a square of the first difference and a square of the second difference to provide an indication of a magnitude of change from the stored value.

7. The method of claim 6 , further comprising:

comparing the indication of the magnitude of change with a threshold value.

8. The method of claim 1 , wherein the at least one measure of the in-phase and quadrature-phase components comprises a first indication of the in-phase component and a second indication of the quadrature-phase component.

9. The method of claim 8 , further comprising:

determining a phase value based on the first and the second indications; and

comparing the phase value with a stored phase value.

10. The method of claim 1 , further comprising:

initiating a polling procedure.

11. The method of claim 10 , further comprising:

initiating the polling procedure at intervals regardless of whether the comparing and determining indicate the presence of the other near-field communicator in near-field range;

wherein the polling procedure is initiated periodically or intermittently.

12. A near-field radio frequency (RF) communicator, comprising:

an inductive coupler configured to inductively couple with a magnetic field (H-field);

a signal provider, coupled to the inductive coupler, configured to transmit a signal;

a signal characteristic determiner, coupled to the inductive coupler, configured to determine a signal characteristic, the signal characteristic indicative of a change in a complex impedance of the inductive coupler; and

a controller configured to perform a comparison between the signal characteristic and a stored value to indicate a presence of another near-field RF communicator and to initiate a polling procedure based on the comparison;

wherein the polling procedure requires more time than determining the signal characteristic and comparing the signal characteristic to the stored value.

13. The near-field RF communicator of claim 12 , wherein the signal characteristic determiner is further configured to determine a first phase component of the signal and a second phase component of the signal, wherein the first phase component and the second phase component are not in phase.

14. The near-field RF communicator of claim 13 , wherein the signal characteristic determiner comprises an IQ mixer.

15. A method of operating an electronic device, comprising:

determining, by a first near-field radio frequency (RF) communicator, whether a second near-field RF communicator is present within near-field range of the first near-field RF communicator; and

performing, by the first near-field RF communicator, when the second near-field RF communicator is present, a polling process to initiate communication with the second near-field RF communicator;

wherein the determining takes less time than the performing.

16. The method of claim 15 , wherein the polling process comprises;

transmitting a wake-up signal to initiate communication with the second near-field RF communicator.

17. The method of claim 15 , wherein the polling process comprises:

transmitting a plurality of wake-up signals in a sequence, each wake-up signal of the plurality of wake-up signals being adapted to initiate communication with a particular type of near-field RE communicator.

18. The method of claim 15 , wherein the first near-field RF communicator includes an inductive coupler; and wherein determining comprises:

detecting in-phase and quadrature-phase components of a voltage in the inductive coupler; and

comparing at least one measure of the in-phase and quadrature-phase components of a signal in the inductive coupler with at least one stored value.

19. The method of claim 18 , wherein determining further comprises:

storing at least one value based on the at least one measure of the in-phase and quadrature-phase components in a memory to provide the at least one stored value for subsequent comparison.

20. The method of claim 19 , wherein determining further comprises:

comparing the in-phase and quadrature-phase components with a previously stored at least one measure; and

determining if the in-phase and quadrature-phase components of a newly received signal are different from the previously stored at least one measure by more than a predetermined threshold amount.

21. A method of operating a near-field radio frequency (RF) communicator, comprising:

transmitting a RF signal;

comparing at least one measure of in-phase and quadrature-phase components of a signal in an inductive coupler that is disposed in the near-field RF communicator with at least one stored value; and

determining whether to initiate polling for another near-field RF communicator based on the comparison;

wherein transmitting, comparing and determining, together, require less energy than polling for the other near-field RF communicator.

22. The method of claim 21 , wherein transmitting, comparing, and determining, together, require less time than polling.