Study Of Ultrasonic Thermometry Based On Fitting The Rising Edge Of Echo Envelope

Temperature measurements have become one of the basic needs in industrial and agricultural production,scientific research as well as daily life of people. The study of temperature measurement method has universal significance. The traditional contact temperature measurement can not meet the requirements in many application scenarios. And some non-contact temperature measurements are limited due to their complexity principle, complex detection device, their high cost and some other reasons. Since the ultrasonic thermometry has its own distinct advantages, it has great potential in the field of temperature measurement. The ultrasonic thermometry based on time-difference is the most commonly used method. It exists problem about poor anti-interference ability and low measuring accuracy. These restrict the development of ultrasonic thermometry. Therefore, raising the anti-jamming capability and measuring accuracy is an important research topic in the field of ultrasonic thermometry.In this article, the subject background is the project of microwave source. To study the methods of ultrasonic thermometry, the time-difference method is used to measure the ultrasonic velocity. And since the ultrasonic time-of-flight is very important, the methods of ultrasonic echo signal de-noising and ultrasonic time-of-flight measurement are improved base on studying current common methods. The specific work of this article can be summarized as follows:① For practical application scenarios, the ultrasound echo signals will inevitably be disturbed, the pretreatment effect of de-noising relates to the accuracy of further processing. The wavelet de-noising is applied to the echo signal de-noising due to its excellent ability on time-frequency analysis. And the selection rules of wavelet basis function and wavelet threshold are studied according to the characteristics of the echo signal. And we put forward a threshold processing function based on weight of average energy. Then its feasibility is proved through some simulation.② On the basis of analyzing the response model of piezoelectric ultrasonic transducer, a new measure method based on fitting the rising edge of echo envelope is proposed. In dual excitation conditions, the signal envelope is extracted by using the Hilbert transform. After the optimization object function of least square method is designed, the particle swarm optimization algorithm is used to estimation of parameters. When we obtain ultrasonic echo envelope model parameter vector, the separation point can be determinate. Then the ultrasonic time-of-flight is obtained. And the thinking of fitting rising edge of echo envelope can also play its role in measuring ultrasonic time-of-flight of ultrasonic multiple echo.③ To meet the need of ultrasonic thermometry, the measurement method proposing in this article is used in temperature measuring experiment. Experimental results show that the proposed method has higher temperature measurement accuracy, and better noise immunity.