Doppler effect results from change in-

Doppler effect: change in frequency because of relative motion between moving source of sound and observer. Example: Sound waves hitting resting parenchyma Sound wave hitting moving RBC The difference gives color coding doppler effect. Color coding: based on direction of flow Flow TOWARDS probe: RED Flow AWAYfrom probe:BLUE Color does NOT depend on aery or vein Intensity of color depends on velocity of flow