Compact modular Doppler system with digital RF processing

Doppler instruments are widely used for evaluation of the hemodynamic of vascular circulation. The objective of the work was to develop a modular acquisition and processing system to enable the construction of various ultrasound instruments. The developed system consists of two electronic boards with dimensions of 130 × 82 mm in sandwich configuration. Digital signal processing was based on an efficient DSP (Blackfin BF537, Analog Devices, USA) with 128 MB RAM and an FPGA (Cyclone III EP3C25, Altera, USA). The system can work as a standalone device with the limited user interface or as a PC peripheral under the control of the application software. The dual channel transcranial PW Doppler flowmeter with multi-gate processing has been the first application of the developed platform. The acquisition module provides the A/D sampling at 64 MSPS rate with 14-bits resolution and supports ultrasonic transducers within the range of 1-16 MHz. The PC software performs signal processing and visualization of color Doppler, spectrum, flow profile and audio. The developed system is a modern technical solution which enables to build portable Doppler instruments of different classes. The developed prototype of transcranial Doppler will be introduced into production soon.