Design On Time Delay Estimation Algorithm And Interaction Of Low Power Acoustic Elasticity Imaging System

Ultrasound elastography technique in detection of breast cancer and cirrhosis has high clinical value, so there are numbers of companies developed based on dynamic quantitative detection of ultrasound elasticity imaging products, which holds the key intellectual property rights and technical standards. But our elastography research is still in its infancy and can not reach the international advanced level, therefore, in the result that products related to the elastography research is dependent on imports. In order to break this situation, Shenzhen Institute of Advanced Technology Institute began working on ultrasound elasticity imaging technology, launched by the National Natural Science and Technology Foundation named dimensional ultrasound elasticity imaging system, of which hardware platform and software platform has been basically completed. But the application clinically relevant index must be compliance, so that the system's ultrasonic transmitter power must be reduced, thus bringing the SNR decreases, giving flexibility detection difficult. The delay estimation algorithm is the most critical elastic detection algorithm that determines the flexibility test results. The thesis is to proposed a time delay estimation algorithm which can remain good quality in low power condition, and is responsible for the design and implementation on an external keyboard of the system.First, the thesis does a survey on the importance of research on the elasticity imaging technology based on acoustic radiation force was given and the review of current research status and future developing trend of elasticity imaging and its key technology were summarized. Then the research content of this discussion was presented and each chapter of this dissertation was arranged. Second, a brief introduction on the traditional time delay estimation algorithm and the proposed maximum likelihood cross correlation time delay estimation algorithm was provided. The model of ultrasonic echo signals and the evaluation standard for time delay estimation algorithm was built. Finally the maximum likehood time delay estimation was proved to achieve better results than conventional time delay estimation algorithm in the low SNR environment. Thirdly, based on a proposed maximum likelihood cross correlation time delay estimation algorithm, this chapter combined wavelet transform algorithm. To achieve better results with wavelet transform, the thesis designed a set of optimal wavelet options.After using this wavelet mother function denoising, get the time delay of the signals using the maximum likelihood cross correlation time delay estimation algorithm,making the algorithm's anti-noise ability further improved.Then, introduce the experimental platform of the subject, including the hardware platform and software platform. Based on this experimental platform, ultrasonic echo signals has been collected and analyzed using wavelet-based maximum likelihood time delay estimation algorithm. Also the design and implementation of embedded system-based external keyboard is designed and implemented.