Modeling of a two-transducer through-wall ultrasonic communication system.
Sebastián Roa Prada, Kyle R. Wilt, Henry A. Scarton, G.J. Saulnier, Jonathan Ashdown, Pankaj Kumar Das, Andrew J. Gavens · The Journal of the Acoustical Society of America · 2010
Ultrasound at 1 MHz is used as a carrier of information across solid walls without penetration. A communication channel is created by bonding two transducers on either side of a solid wall. The outside transducer transmits a continuous wave generating an acoustic field. The inside electronics are powered by harvesting the electrical output of the inside transducer. Digitized bits, representing the value of an analog signals measured on the inside (such as temperature), are used to alternate the electrical load of the inside transducer between two finite values. Changes in the electrical load of the inside transducer modify its acoustical impedance as seen by the incident waves coming from the wall, which in turn modulates the amplitude of the reflected signal. This modulated wave is detected at the electrical terminals of the outside transducer, where it is then demodulated to recover the data. The mechanical components of the system are modeled in connection to the electronic circuits by means of electro-mechanical analogies. Simulation of the communication system is performed using the electric circuit simulation package PSPICE. Simulation, finite element solutions, and experimental results are presented and discussed. Digital data communication rates exceeding 50 000 bits/s are achieved.