Low Depth Time Reversal Modulation Technique for Ultrasonic Guided Waves-based Communications

Ultrasonic guided waves (GWs) have the peculiar capability to travel long distances with minimal attenuation; thus, they represent a compelling alternative which exploits the mechanical waveguide as a form of communication channel and the elastic waves as the signals carrying information. The objective of this work is to implement an effective GWs-based communication system which takes advantage of the channel reciprocity to counteract reverberations and multi-path fading inherent to the dispersive nature of GWs, simultaneously compensating the in-operation mutual interferences between active transducers. More in detail, a strategy based on the Time-Reversal (TR) method is considered, which is combined in an original fashion with a low-depth synthesis of the time-reversed waveforms to be compatible with low-cost switching amplifiers. Experiments performed by simulating the propagation in Aluminum plates suggested that a communication rate up to tenth of kHz can be achieved in presence of highly digitized wave-forms without losing the original information content.