Doppler (redirected from Doppler, Johann Christian)

Doppler /Dop·pler/ (dop´ler) see under ultrasonography.

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color Doppler  color flow Doppler imaging.

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Doppler

The Doppler effect refers to the apparent change in frequency of sound wave echoes returning to a stationary source from a moving target. If the object is moving toward the source, the frequency increases; if the object is moving away, the frequency decreases. The size of this frequency shift can be used to compute the object's speed—be it a car on the road or blood in an artery. The Doppler effect holds true for all types of radiation, not just sound.

Mentioned in: Abdominal Ultrasound

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Doppler

an Austrian physicist and mathematician.

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duplex Doppler imaging

see doppler ultrasound.

Doppler effect

the relationship of the apparent frequency of waves, as of sound, light and radio waves, to the relative motion of the source of the waves and the observer, the frequency increasing as the two approach each other and decreasing as they move apart.

The Doppler effect can be experienced when a train whistle or automobile horn produces a continuous sound as it approaches and passes a listener. The pitch of the sound suddenly falls as the source passes the listener.

Doppler shift

the change in frequency that occurs when high frequency sound waves are reflected from a moving surface; the basis for doppler ultrasound.