Pulsed-doppler Effect
Pulsed-doppler Effect - Related Videos
14:19
Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction
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Cited by 11 •
2013
We describe examination of fetal cardiac function with contemporary functional fetal echocardiography and fetoplacental Doppler ultrasound using the VisualSonics VEVO 2100 microultrasound in a surgically induced model of intrauterine fetal growth restriction in a rabbit.
09:12
Sound Waves and Doppler Shift
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2023
Source: Arianna Brown, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA Waves are disturbances that propagate through a material medium or empty space. Light waves can travel through a vacuum and some forms of matter, and are transverse in nature, which means that the oscillations are perpendicular to the direction of propagation. However, sound waves are pressure waves that travel through an elastic medium like air,...
00:56
Doppler Effect - I
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2023
The Doppler effect and Doppler shift were named after the Austrian physicist and mathematician Christian Johann Doppler in 1842, who conducted experiments with both moving sources and moving observers. Consider an observer standing on a street corner, observing an ambulance with a siren sound passing by at a constant speed. The observer experiences two characteristic changes in the sound of the siren. Initially, the sound increases in loudness as the ambulance approaches and decreases in...
01:05
Doppler Effect - II
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2023
The Doppler effect has several practical, real-world applications. For instance, meteorologists use Doppler radars to interpret weather events based on the Doppler effect. Typically, a transmitter emits radio waves at a specific frequency toward the sky from a weather station. The radio waves bounce off the clouds and precipitation and travel back to the weather station. The radio frequency of the waves reflected back to the station appears to decrease if the clouds or precipitation are moving...
10:46
Doppler Optical Coherence Tomography of Retinal Circulation
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Cited by 29 •
2012
Total retinal blood flow is measured by Doppler optical coherence tomography and semi-automated grading software.
FAQs
Range gating links each Doppler measurement to a selected depth by using the timing of returned echoes. This prevents motion signals from different locations from being treated as one measurement, allowing the instrument to examine blood-cell motion at a defined position within a vessel or cardiac region. The result is spatially specific flow information.
The sign of the frequency shift indicates flow direction, while its magnitude indicates the speed of the scattering targets. Reading these properties together gives more than a numerical velocity value: it shows how fast blood cells move and which way they travel. That combined interpretation is important when assessing circulation at a selected measurement location.
Short ultrasound pulses provide the timing information needed to associate an echo with depth, while the returned signal supplies the frequency information used to assess motion. Keeping these roles connected allows the system to distinguish where motion occurs from how the scattering targets move. This combination is central to measurements that must resolve flow at defined locations.
First, a transducer sends a short ultrasound pulse into the body. The system receives echoes from scattering targets, uses their timing to relate the signal to a selected depth, and analyzes the frequency shift. It then interprets the shift's sign and magnitude to estimate flow direction and speed at that location.
Researchers can use pulsed-Doppler measurements when they need noninvasive information about blood flow, vessel function, or cardiac performance. The method is especially relevant when the measurement must be tied to a defined location rather than treated as undifferentiated motion. These capabilities make it useful in diagnostic ultrasound and biomedical instrumentation.
In bioengineering, the technique connects wave-based sensing with physiological measurements. Echo timing provides location-specific information, and frequency-shift analysis supplies motion information from blood cells and other scattering targets. Together, these outputs help biomedical instruments characterize circulation and cardiac behavior without requiring an invasive measurement, supporting assessment of vessel and heart function.