Ultrasonic Data Acquisition: Signal to Noise Ratio Improvement

In this paper an ultrasonic data acquisition system and a digital signal processing algorithm in order to improve signal to noise ratio and ensure the envelope detection are presented. The data acquisition system is based on an ADuC812 micro-converter and a pair of MA400ST/R ultrasonic transducers. The received data are transmitted to a host computer via an RS232 serial interface. The digital signal processing is performed in Matlab, and, makes extensive use of the well known moving average filter (MAF) algorithm. MAF are extensively used as low-pass filters due to their good smoothing performance and ease of implementation in software and hardware as well. In this paper we will demonstrate that using the same MAF algorithm, one can address all the filtering tasks (low-pass, high-pass, notch), implied by the process of envelope detection of ultrasonic echoes.