The market for process instruments generally requires low cost devices that are robust,\nsmall in size, portable, and usable in-plant. Ultrasonic torsional guided wave sensors have received\nmuch attention by researchers for measurement of viscosity and/or density of fluids in recent years.\nThe supporting electronic systems for these sensors providing many different settings of sine-wave\nsignals are bulky and expensive. In contrast, a system based on bursts of square waves instead of\nsine waves would have a considerable advantage in that respect and could be built using simple\nintegrated circuits at a cost that is orders of magnitude lower than for a windowed sine wave device.\nThis paper explores the possibility of using square wave bursts as the driving signal source for the\nultrasonic torsional guided wave viscosity sensor. A simple design of a compact and fully automatic\nanalogue square wave front-end for the sensor is also proposed. The successful operation of the\nsystem is demonstrated by using the sensor for measuring the viscosity in a representative fluid.\nThis work provides the basis for design and manufacture of low cost compact standalone ultrasonic\nguided wave sensors and enlightens the possibility of using coded excitation techniques utilising\nsquare wave sequences in such applications.
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