Abstract
Ultrasound Doppler techniques are widely employed in detecting the velocity of moving fluids both in medical and industrial applications. Echo Doppler electronics systems include a highly sensitive front-end suitable to processing the very low power ultrasound echoes received by the transducer. Moreover, the front-end input bandwidth typically ranges between 100 kHz and 10 MHz, which is the same frequency range where modern switching regulators work. Thus, the front-end is particularly prone to the noise produced by the suppliers that power the board itself. Electromagnetic interference (EMI) filters and spread-spectrum modulation of the switching regulator frequency help, but the results are often not optimal, and unacceptable artifacts are visible in the Doppler spectrum. In this paper a spread-spectrum modulation is proposed that concentrates the switching noise in the low-frequency range of the Doppler spectrum (e.g., 0–100 Hz). This range is removed by the high-pass clutter filter normally used in velocity Doppler investigations, thus switching noise and artifacts are eliminated. The method is verified through mathematical simulations and tested in measurements carried out with a research Doppler system. An example is presented in which the artifacts present during the investigation of a 0.4-m/s flow in a 25.4-mm diameter pipe are effectively removed by the proposed method.
Highlights
Ultrasound Doppler is employed in several medical and industrial applications for fluid velocity investigation
The ultrasound system should be equipped with a very sensitive front-end receiver, which, in turn, is prone to pick up electronic noise from the system itself
In this paper we present a spread spectrum method that exploits the particular features of Doppler data processing for effectively cancelling the power switching noise in the Doppler spectrum
Summary
Ultrasound Doppler is employed in several medical and industrial applications for fluid velocity investigation. Clinical echographs exploit echo Doppler for acquiring important information about how blood moves in arteries [1,2,3], and industries employ similar techniques for detecting the velocity profile of fluids flowing in pipes. In this case, the final application can be, for example, accurate volume flow detection or rheological fluid characterization [4,5,6]. The echo signal backscattered from the particles dispersed in the fluid (e.g., erythrocytes in the blood or powders in water) is quite weak This issue is severe in industrial applications where attenuating fluids or suspensions flow in pipes with large diameters. The ultrasound system should be equipped with a very sensitive front-end receiver, which, in turn, is prone to pick up electronic noise from the system itself
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
