基于FPGA的数字超声内窥镜接收系统设计

根据数字超声成像的要求和超声信号的特点,设计了由高速采样电路和FPGA正交解调电路组成的数字超声内窥镜接收系统。采样电路由AD8138和AD9235实现,对放大后的超声回波信号直接进行模数转换;FPGA利用内部RAM、乘法器、IP核和宏模块构建数字正交解调电路,提取超声回波信号的幅度;获取的幅度信息经USB2.0接口电路送入计算机显示。对玻璃杯进行的静止扫描成像实验,验证了接收系统的小信号检测能力,可以检测到信噪比约为4dB的回波信号;对玻璃杯进行的旋转扫描成像实验,表明接收系统可用于数字超声内窥镜成像。

Design of Receiving System of Digital Ultrasonic Endoscope Based on FPGA

According to the requirement of digital ultrasonic imaging,a receiving system is designed for digital ultrasonic endoscope which is composed of a high-speed ADC and a quadrature demodulation circuit based on FPGA.The ADC directly samples the amplified echo using AD8138 and AD9235;FPGA extracts the envelope of digital echo by its internal digital quadrature demodulation circuit which is implemented by RAM,multiplier,IP core and megafunctions in FPGA;amplitude of echo is transferred to computer for imaging through USB2.0 interface.The experiment of stationary scanning glass proves the detecting ability of the receiving system,which can obtain the amplitude of signals whose SNR is 4 dB.The experiment of rotating scanning glass proves that the receiving system can be utilized in digital ultrasonic endoscope.