The Design And Implementation Of Ultrasonic Transducer Performance Tester

Due to the characteristics of high reliability, easiness in installation and maintenance, high sensitivity in the small flow, ultrasonic flowmeter is widely used in flow measurement. As an energy conversion device which can transform energy between electrical and mechanical, ultrasonic transducer plays a key role in ultrasonic flowmeter, its performance indexes and matching degree performance parameters of ultrasonic transducers which are applied in the same flowmeter have an effect on the accuracy of ultrasonic flowmeter directly. However, there is lack of unified standards on the performance evaluation of the ultrasonic transducer at home, the study of transducer parameter matching is ignored by flowmeter enterprises. Therefore, studying the ultrasonic transducer performance testing has great meaning.At present, many issues exist in the performance testing methods of ultrasonic transducers, for example, the high cost of special testing instruments, single index and low efficiency and complicated of subentry testing. To solve these problems, based on the ultrasonic flowmeter, the paper designs an ultrasonic transducer performance tester, which has advantages of low cost and multiple parameters testing. Resonance frequency and anti-resonance frequency, resonance impedance and anti-resonance impedance, emission signal amplitude and received signal amplitude are proposed in the performance tester. The paper is aimed at evaluating the comprehensive performance of ultrasonic transducers, at same time, providing a more scientific and reasonable basis for evaluating whether the technical index of ultrasonic transducer is qualified and the two transducers are fit for applied to the same flowmeter.In this paper, FPGA is selected as the core controller, touch screen is used to select test items and display test results. As the exciting signals generator, FPGA send corresponding excitation signal by frequency doubling then division. Response signal is dealt by signal modulation circuit and then converts the analog signal to digital signal by high speed A/D converter. Verilog hardware description language is used to realize the data collection and data pretreatment. With sweep excitation signal, the resonance frequency and anti-resonant frequency are acquired by comparing the sampling data of different frequency, the frequency response curve is displayed intuitively on touch screen. When the alternative method is employed in testing resonance impedance and anti-resonance impedance, in order to solve the issues of manpower to read and record measured data, constant current source circuit is used to calculate and store the equivalent impedance automatically. For existing amplitude tester exists some disadvantages, such as single signal source, hand regulation oscilloscope and reading. To solve the problems, this paper succeeds in setting arbitrarily the excitation signal, samples transmitting and receiving signals respectively by controlling the time and shows the amplitudes on touch screen directly. Verilog HDL is adopted to integrate UART central functions, serial port communication is used to send the test data to PC, process and match through the PC.Finally, many experiments have been done with multiple transducer manufacturers, and then compare the test data obtained from the tester with the data from special instruments. The comparison results show that the precision of the performance tester meets the design requirements and the tester can achieve the performance estimation.