Research Of Signal Reception And Processing System Of Digital Ultrasonic Endoscope

The ultrasonic endoscope, which combines an electronic endoscope and a mini ultrasonic imaging system, sends a micro ultrasonic probe into coelom through the biopsy channel of the electronic endoscope. In this way, the ultrasonic endoscope can get pictures of the alimentary canal mucosal surface and images of the full histology of the digestive organs simultaneity. Compared to other ultrasonic imaging methods, Endoscopic ultrasound imaging is non-invasive and non-ionizing radiation advantages. Endoscopic ultrasonography has been proven very effective for diagnosing gastrointestinal diseases.However, because the ultrasound endoscope uses a miniature ultrasound probe, the power of ultrasound probe transmit is much less than external ultrasound imaging. The limited reception area can cause that the echo amplitude is very low, signal to noise ratio is also poor. The old system analog echo receiver system can not meet the requirements of the clear ultrasonic imaging, so it is very necessary to redesign high-gain, low noise analog front-end receiving system. In addition, in order to obtain high SNR images, FPGA-based ultrasonic digital signal processing module is designed.The main researches of this dissertation are shown as the following:1. For the ultrasonic transducer and the echo characteristics, based on dual VGA analog front-end receiver circuit is designed to improve the SNR of the imaging system.2. For the echo which has been amplified and gain compensated, the active filter is designed in comparison of the analog filter implementation scheme. Based on the Spice simulation results, the improved performance of the filter is applied to existing systems to suppress the noise.3. On basis of the original processing system, digital filtering, pulse compression, gray stretch module is added. In order to meet the requirements of the future system,the PCB of processing system based on Cyclone EP3C40Q is drew.4. Experimental platform is built to complete the system of joint commissioning of each module test. Besides a beaker and animal tissue rotation scan imaging experiment is conducted successfully. The system outputs rectangular coordinates of the ultrasound images at 5 frames per second, which proves the performance of the EUS.