Real-time implementation of Kalman filter to improve accuracy in the measurement of time of flight in an ultrasonic pulse-echo setup.

In this paper, we demonstrate a hardware implementation of Kalman filter to enhance accuracy in the measurements of time-of-flight in an ultrasonic pulse echo technique (operated at 10 MHz). Pulser-receivers and other respective circuit units are designed using off-the-shelf electronic components. The advanced reduced instruction-set computing machine processor based Raspberry Pi single board computer is used to implement the Kalman filter and control various processes. Additionally, a graphical user interface is designed using Qt software, under the Debian open source operating system. The software has capability to measure and display the time-of-flight and ultrasonic propagation velocity in a liquid under test. The designed system with the Kalman filter exhibited an extremely small error of about 0.01% in the time-of-flight measurements compared with other systems. The functionality of the developed approach to measure time of flight and thereby ultrasonic velocity with significant improvement has been discussed in this article. It was experimentally verified that by improving other parameters such as the separation between the transducer and the reflector and cell structure, significant improvement in the accuracy of ultrasonic velocity in the liquid under test is achieved.