医学超声内镜中同步编码激励技术的设计与实现

为了提高医学超声内镜系统中的探测深度、分辨率及成像质量,在超声内镜成像系统中采用编码激励技术,首次将普遍用于开关电源电路设计中的"半桥"电路引入超声内镜编码激励电路.在只有正电压电源供电的情况下产生正负高压激励脉冲,利用电机转动的编码信号,设计了基于CPLD的同步编码激励电路,在保证与超声内镜主机FPGA同步的基础上,简化了超声内镜系统内信号的传递.实验中,同步编码激励电路发射的编码激励信号与理论码型一致,通过人体体模实验,获得的回波波形幅度达1.0Vpp,噪声20×10-3VPP~30×10-3Vpp,信噪比高达34 dB,波形与仿真结果一致.

Design and Implementation in Ultrasonic of Synchronous Coded Excitation Endoscope System

In order to improve the probing depth, resolution, and image quality, ultrasonic endoscope ima ging system generally applies coded exciting technique. ＇ Halfbridge circuit＇ which is widely used in the design of switching power supply circuit was employed in the ultrasonic endoscope coded excitation circuit for the first time. The circuit could generate positive and negative high voltage excitation pulse from only one positive voltage power supply. Based on the motor rotation coded signal, synchronous coded excitation circuit was generated with the help of CPLD. As a result, this design simplified the transmission of signals within the ultrasonic endoscope system while being synchronized with the ultrasonic endoscope host FPGA at the same time. In the experiment, the coded signal emitted by the synchronous coded excitation circuit is consistent with the theoretical pattern. Through the human body phantom experiment, we obtain 34 dB sig naltonoise ratio, echo waveform with amplitude of 1.0Vpp and noise 20 x 103Vpp to 30 x 103 Vpp. Wave form and simulation results are found to be consistent.