Near field RF communicators

Initiating a near field communication (NFC) polling sequence when a device is within range

A near field RF communicator is configured to perform a detection process 500-550 to determine whether another near field communicator is within range and, if so, to perform a polling process 570 to initiate communication. The detection process has a shorter duration than the polling process and consequently has a lower energy requirement. The RF communicator has an inductive coupler (200, fig. 1) for coupling with a magnetic field and a signal provider (driver 210). The detection process involves comparing a signal characteristic 520 relating to a change in complex impedance of the inductive coupler with a stored value, and determining whether this is indicative of the presence of a near field RF communicator. The signal characteristic may comprise in-phase and quadrature phase components of the signal. In this way, the polling process is performed only when it is necessary.