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Doppler Velocity Log (DVL): Some ships are equipped with sonar instruments that can measure the Doppler shift in a sound pulse generated by the ship's motion as it reflects off the ocean bottom or off particles in the water. The speed measurements from a Doppler instrument can therefore be relative to the ground, or to the water.
A chip log consists of a wooden board attached to a line (the log-line ). The log-line has a number of knots at uniform intervals. The log-line is wound on a reel so the user can easily pay it out . Over time, log construction standardized. The shape is a quarter circle, or quadrant with a radius of 5 inches (130 mm) or 6 inches (150 mm), [1 ...
Electromagnetic log. An Electromagnetic Log, sometimes called an "EM log", is an electronic sensor which measures the speed of a vessel through sea water. Like many other technologies, its name derives from the traditional chip log. It makes use of Faraday's law of induction by measuring the EMF induced in water moving through a magnetic field ...
The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. [1] [2] [3] The Doppler effect is named after the physicist Christian Doppler, who described the phenomenon in 1842. A common example of Doppler shift is the change of pitch heard when a ...
Doppler effect. The emitted signal toward the car is reflected back with a variation of frequency that depends on the speed away/toward the radar (160 km/h). This is only a component of the real speed (170 km/h). The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842, is the difference ...
An acoustic doppler current profiler ( ADCP) is a hydroacoustic current meter similar to a sonar, used to measure water current velocities over a depth range using the Doppler effect of sound waves scattered back from particles within the water column. The term ADCP is a generic term for all acoustic current profilers, although the abbreviation ...
A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and continuous-wave radars, which were formerly separate due to the complexity of the electronics .
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