A wireless power supply system that detects communications in the input power to the switching circuit. In this aspect of the invention, the wireless power supply includes a detector for generating a signal indicative of the current in the input to the switching circuitry, a band-pass filter for filtering the detected signal, an amplifier for amplifying the filtered signal, a filter for filtering the amplified signal and a comparator for converting the final signal into a stream of high and low signals that can be passed to a controller for processing as binary data stream. In a second aspect, the wireless power supply system includes a detector for generating a signal that varies in dependence on changes in the phase relationship between the current and the voltage in the primary-side tank circuit, a band-pass filter for filtering the signal, an amplifier for amplifying the filtered signal, a filter for filtering the amplified signal and a comparator for converting the final signal into a stream of high and low signals that can be passed to a controller for processing as binary data stream.