Microprocessors and micro-controllers have been extensively put to use by researchers to acquire, process and display experimental data in user- defined form. Hence, conventional instrumentation is being replaced by PC-based instrumentation, by effectively utilizing the processing power and software capabilities of a microprocessor. Low amplitude ultrasonic propagation is powerful and effective method to probe the properties of a medium since the properties of the medium do not change during the propagation. Thus, ultrasonic techniques have been extensively used as a basic non- destructive tool for material characterization in research, industry and medicine. This book is an attempt to provide some insight into the development of PC- based high frequency techniques for ultrasonic characterization of a medium. The authors have aptly presented a review of various ultrasonic techniques, hardware, circuit design concepts. This work articulates the modern concepts of instrumentation in the design of PC-based pulse technique and measurements of temperature and viscosity, which will be useful to students who intend to pursue research and design PC-based instrumentation.