ISSN:
1741-0444
Keywords:
Blood flow
;
Doppler effect
;
Instrumentation
;
Perivascular
;
Phase-locked loop
;
Transducer
;
Ultrasound
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract The paper details the design of the signal processing system of an ultrasonic Doppler flowmeter intended for perivascular application. The system is designed to work in conjunction with a transducer system described in an earlier paper, in a range of vessels varying from 5 mm to 12 mm. The system incorporates conventional quadrature processing for directional discrimination and uses phaselocked loop technology to extract signals corresponding to the instantaneous mean frequency (velocity equivalent). The use of a PLL also permits the extraction of a quasi-spectral analysis signal. The baseline stability of the Doppler system is enhanced by the use of an auto-zeroing system which enables the system to resolve Doppler shifts down to 20Hz. Testing of the complete transducer/signal processor system in a hydraulic rig demonstrates the ability of the flowmeter to accurately measure both steady and pulsatile flow.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02442258
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