echo pulses

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• Echo sounding — pulses directed from the surface or from a submarine vertically down to measure the distance to the bottom by means of sound waves. HistoryAfter the disaster of the Titanic in 1912, the German physicist Alexander Behm conducted some research to… …   Wikipedia

• echo sounding — noun a) The technique of using reflected pulses of sound to determine depth or the location of objects (or fish) under water. b) A particular measurement made using this technique …   Wiktionary

• Spin echo — In nuclear magnetic resonance, spin echo refers to the refocusing of precessing nuclear spin magnetisation by a 180° pulse of resonant radiofrequency.The NMR signal observed following an initial excitation pulse (orange in diagram) decays with… …   Wikipedia

• spin echo — n a signal that is detected in a nuclear magnetic resonance spectrometer, that is an echo like replication of a free induction decay produced by a planned series of radio frequency pulses, and that can be used to extract more information from a… …   Medical dictionary

• gradient echo — n a signal that is detected in a nuclear magnetic resonance spectrometer that is analogous to a spin echo but is produced by varying the external magnetic field following application of a single radio frequency pulse rather than by application of …   Medical dictionary

• photo echo — noun a form of resonance sometimes observed as a coherent pulse of light after two similar pulses have traversed a medium …   Wiktionary

• radar — /ray dahr/, n. 1. Electronics. a device for determining the presence and location of an object by measuring the time for the echo of a radio wave to return from it and the direction from which it returns. 2. a means or sense of awareness or… …   Universalium

• Medical ultrasonography — This article is about using ultrasound to image the human body. For imaging of animals in research, see Preclinical imaging. Sonography redirects here. For the tactile alphabet called sonography , see Night writing. Medical ultrasonography… …   Wikipedia

• Weather radar — in Norman, Oklahoma with rainshaft …   Wikipedia

• Nuclear magnetic resonance — This article is about the physical phenomenon. For its use as a method in spectroscopy, see Nuclear magnetic resonance spectroscopy. NMR redirects here. For other uses, see NMR (disambiguation). First 1 GHz NMR Spectrometer (1000 MHz,… …   Wikipedia

• Synthetic aperture radar — (SAR) is a form of radar in which the highly directional (and thus very large) rotating antenna used by conventional radar is replaced with many low directivity small stationary antenna positions scattered over some area near or around the target …   Wikipedia