Abstract

Coded excitation is often used to improve signal to noise ratio (SNR) when ultrasound signals are acquired. A sequence of pulses is sent to increase the energy that is inserted into the medium. At the receiver the signals are pulse compressed so that a temporally short output with high SNR results. Commonly the technique only employs relatively short codes. This limitation is a result of the need to receive signals from relatively closely located reflectors. The author and his co-workers have recently presented an encoding method that overcomes that limitation. In the author’s implementation very long codes are transmitted. With this a large improvement in SNR can be achieved but it also raises the question of how the technique performs in a dynamic environment where the probe is scanned over a surface. In this work the effect of motion on the acquisition process with long coded excitations is investigated. It was found that the process is affected by motion, but it remains robust at low speeds (a few m/s). For example, when a particular scenario was investigated that analysed signal reflections from a specimen containing a non-uniform inclined (17degrees) surface, the SNR dropped by 6dB when the probe moved at 1 m/s.

How to Cite:

Cegla, F. B., (2019) “Evaluation of the effect of motion on ultrasonic signals acquired using coded excitation”, Review of Progress in Quantitative Nondestructive Evaluation .