Study Of Wavelet Transform Device Of Saw Type

The technology of surface acoustic wave had been developed as an emerging field of science and technology in the late 1960s. It is a marginal discipline of combining acoustics with electronics. Because the propagation velocity of SAW is 100,000 times as slow as that of electromagnetic wave, so we can sample and process easily in its dissemination path. We can use SAW devices to simulate various functions of electronics, which can lead to the realization of ultra-small and multi-functional devices. In addition, SAW devices effectively provide the signal processing functions in the VHF and UHF band, which can not be easily obtained by the other means. Moreover, SAW devices have advantages such as small size, light weight and strong anti-radiation as well as low cost and good processing reproducibility. Therefore, SAW devices are developing rapidly and are widely used in various electronic devices such as televisions, mobile, phones, radar, and communications and so on.The concept of wavelet transform is first proposed by J.Morlet Engineer who engaged in oil signal processing in France in 1974. The theory of wavelet transform has developed into a new branch of mathematics in recent years. Compared with Fourier transform and Window Fourier transform, Wavelet transform is a local transformation of time and frequency. Thus it can be effectively used to extract information from the signals. A lot of tough problems, which can not be solved by Fourier transform, have been solved by multi-scale analysis of signals by means of flexing and translating operation. It is especially applicable to detecting transitional abnormal phenomena hidden in normal signals, and can expand their components. Thereby, wavelet transform was known as "Mathematical Microscope". The close integration of the theoretical research and application of wavelet analysis leads to eye-catching achievements in the field of information technology.Wavelet transform has broad prospects of application in the fields of signal detecting, signal processing, and image processing and so on. It tends to spread rapidly to the other fields. The research of wavelet transform has become a hot spot in many fields. Now, the wavelet transform is realized mainly by means of computer program which needs lots of workloads and involves very complicated algorithm. The research of realizing signal wavelet transform on hardware just began in recent years. By combining the SAW technology with wavelet transform technology, we have successfully manufactured wavelet transform device which would provide users with great convenience.The dissertation is formed as follows:1. We introduce the current development and characteristic of the technology of SAW and expatiate on the current research and developing trends of SAW devices.2. We expound the principle of the generation of SAW and the working principle of interdigital transducer. IDT is made of the piezoelectric material depositing on the surface, the pattern of which resembles the cross-fingers. It can produce SAW. IDT has been used widely due to its flexibility of design and convenience of manufacture.3. The theories of SAW and wavelet transform are introduced respectively. And we further explain that wavelet transform is essentially a convolution operation. Based on the convolution operation, we expound the structure of SAW device and its working principle. Finally we conclude that wavelet transform can be realized by using SAW device.4. We discuss the relationship between IDT impulse response and its geometric structure. And the introduction of the model of IDT impulse response which has the same overlapping digit and periodical cycle is also presented. Based on this model, we further elaborate the model of IDT of wavelet type impulse response. Finally we expatiate on the receiving IDT impulse response model.5. By combining the SAW technology with wavelet transform technology, we have successfully manufactured wavelet transform device which would provide users with great convenience.6. This device was tested, the results of test show that: Wavelet transform can be realized with SAW devices. But there are some errors. We can reduce the errors after analyzing the sources of these errors.