Transfer of Acoustic Wireless Power and data Through a Metal Wall Using a Common Link with Higher Resonance Modes

Abstract

For a wireless power and data transmission system, when a shared link is used for both purposes, the cross-talk interference from higher harmonics of the power transfer interface affects the reliability of bidirectional data communication. In literature [1] and most applications, the carrier frequency for data transfer is kept at least one order of magnitude higher than the power transfer frequency so that the cross-talk can be minimized, but not eradicated completely. The opposite, however, selecting an operational frequency of the data transfer lower than that of the power allows for extracting the data with a simple low pass filter instead of bandpass filters. Moreover, harmonics from the power transfer interface cannot fall into the data communication band. To exploit this possibility for a shared ultrasonic link, we present a novel technique to transfer power and data through a 20 mm thick metal wall, involving only one pair of transducers while keeping the data transfer frequency lower than the power transfer frequency.