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A flexible system for the launch and reconstruction of localized acoustic waves

University of British Columbia

A synthetic array system for launching and reconstructing localized acoustic waves has been developed. This low cost system is easily changed to many different configurations and for many different experiments. The major components of this system consist of an ultrasonic transducer transmitter-receiver pair, a high bandwidth amplifier, a single axis motion stage and PC-based data generation, acquisition and control cards. In addition to the design and assembly of this system, the equipment was further characterized so that the performance characteristics can be accounted for in future experiments. The signal amplitude decay with increasing transmitter-receiver distance behaves approximately as predicted by theory. The amplitude remains relatively constant up to the near field boundary. In the far field, the signal amplitude decays at a rate inversely proportional to the transducer separation. Transducer response as a function of the angle between the transmitter and receiver studied. Experimental measurements showed that transmitted fields are highly directional, similar to that predicted by theory. A method was devised to reconstruct received signals. Signals are first processed to remove unwanted low frequency noise. The signal is then integrated twice to recover the original signal, as predicted by theory. As a final confirmation of the operation of this system, a sample FWM pulse was generated using a 21 x 21 array of sources at a distance of 12 cm from the source array. The reconstructed result is compared with the theoretically reconstructed result as well as the ideal FWM pulse. The experimental results show characteristics similar to that which is predicted by theory. All required equipment and procedures have been devised to launch localized acoustic waves with this system. The experimental setup is ready to begin further experiments in localized acoustic waves.

Thesis/Dissertation

application/pdf

2009-02-12

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http://hdl.handle.net/2429/4515

Electrical and Computer Engineering

University of British Columbia

UBCV

DSpace