181:". The method is robust and provides good quality mean current profiles but has limited space-time resolution. When the transmit pulse consists of coded elements that are repeated, the method is referred to as "repeat sequence coding" or "broadband". This method improves the space-time resolution by a factor of 5 (typical). Commercially, this method was protected by US patent 5615173 until 2011. The pulse-to-pulse coherent method relies on a sequence of transmit pulses where the echo from subsequent pulses are assumed not to interfere with each other. This method is only applicable for very short profiling ranges but the corresponding improvement in space time resolution is of order 1000.
234:
calculating the velocity from a window centered around the bottom position. When an ADCP is mounted on a moving ship, the bottom track velocity may be subtracted from the measured water velocity. The result is the net current profile. Bottom track provides the foundation for surveys of the water currents in coastal areas. In deep water where the acoustic signals cannot reach the bottom, the ship velocity is estimated from a more complex combination of velocity and heading information from
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Depending on the mounting, one can distinguish between side-looking, downward- and upward-looking ADCPs. A bottom-mounted ADCP can measure the speed and direction of currents at equal intervals all the way to the surface. Mounted sideways on a wall or bridge piling in rivers or canals, it can measure
308:
and direction. The wave height is estimated with a vertical beam that measures the distance to the surface using the echo from short pulses and simple peak estimation algorithms. The wave direction is found by cross correlating the along-beam velocity estimates and the wave height measurement from
113:
transducers to transmit and receive sound signals. The traveling time of sound waves gives an estimate of the distance. The frequency shift of the echo is proportional to the water velocity along the acoustic path. To measure 3D velocities, at least three beams are required. In rivers, only the 2D
250:
In rivers, the ADCP is used to measure the total water transport. The method requires a vessel with an ADCP mounted over the side to cross from one bank to another while measuring continuously. Using the bottom track feature, the track of the boat as well as the cross sectional area is estimated
216:
within the water column or directly at the seabed, water current and wave studies may be performed. They can stay underwater for years at a time, the limiting factor is the lifetime of the battery pack. Depending on the nature of the deployment the instrument usually has the ability to be powered
233:
By adjusting the window where the
Doppler shift is calculated, it is possible to measure the relative velocity between the instrument and the bottom. This feature is referred to as bottom-track. The process has two parts; first identify the position of the bottom from the acoustic echo, then
362:
interference, covers 6–12% of the water column and, for instruments looking up toward the surface, the loss of velocity information close to the surface is a real disadvantage. Cost is also a concern but is normally dwarfed by the cost of the ship required to ensure a safe and professional
255:
between the vector track and the current velocity. The method is in use by hydrographic survey organisations across the world and forms an important component in the stage-discharge curves used in many places to continuously monitor river discharge.
325:
and thereby estimate the dissipation rate. The application of ADCPs to turbulence measurement is possible from stationary deployments but can also be done from moving underwater structures like gliders or from subsurface
350:
over a significant portion of the water column. Since the start in the mid-1980s, many thousand ADCPs have been used in the world oceans and the instrument has played a significant role in our understanding of the world
114:
velocity is relevant and ADCPs typically have two beams. In recent years, more functionality has been added to ADCPs (notably wave and turbulence measurements) and systems can be found with 2,3,4,5 or even 9 beams.
374:
navigation and echolocation. The effect depends on the frequency and the power of the instrument but most ADCPs operate in a frequency range where noise pollution has not been identified to be a serious problem.
64:
scattered back from particles within the water column. The term ADCP is a generic term for all acoustic current profilers, although the abbreviation originates from an instrument series introduced by
173:
Three common methods are used to calculate the
Doppler shift and thus the water velocity along the acoustic beams. The first method uses a monochromatic transmit pulse and is referred to as "
309:
the vertical beam. Wave measurements are typically available for seafloor-mounted instruments but recent improvements permit the instrument to be mounted also on rotating subsurface buoys.
264:
For underwater vehicles, the bottom tracking feature can be used as an important component in the navigation systems. In this case the velocity of the vehicle is combined with an initial
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ADCPs with pulse-to-pulse coherent processing can estimate the velocity with the precision required to resolve small scale motion. As a consequence, it is possible to estimate
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aspect, where a single, stationary instrument can measure the current profile over ranges exceeding 1000 m. These features allow for long term measurements of the
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has a preconfigured constant value. Finally, the results are saved to internal memory or output online to an external display software.
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The main disadvantage of the ADCPs is the loss of data close to the boundary. This mechanism, often referred to as a
130:
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ADCPs with three beams resolve the three components of velocity. (Models
Aquadopp Profiler 1MHz and 0.6 MHz, Nortek)
295:
The AWAC (Acoustic Wave and
Currents) is a type of ADCP specifically designed for surface wave height and direction.
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153:, and uses this to estimate scale the frequency shift to water velocities. This procedure assumes that the
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the current profile from bank to bank. In very deep water they can be lowered on cables from the surface.
536:. Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment
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parameters from properly configured ADCPs. A typical approach is to fit the along beam velocity to the
206:
768:
758:
753:
671:
616:
392:"Repeat-Sequence Coding for Improved Precision of Doppler Sonar and Sodar, R. Pinkel and J. A. Smith"
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39:
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for data communication. Deployment duration can be extended by a factor of three by substituting
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after adjustment for left and right bank areas. The discharge can then be calculated as the
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110:
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519:"System and method for determining directional and non-directional fluid wave and current"
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218:
142:
908:
681:
606:
580:
343:
150:
146:
57:
902:
831:
811:
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611:
446:"Pulse-to-Pulse Coherent Doppler Sonar Signal Processing Techniques, Roger Lhermitte"
352:
347:
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The two major advantages of ADCPs is the absence of moving parts that are subject to
277:
138:
129:, a compass to know the heading, and a pitch/roll sensor to know the orientation. An
50:
42:
862:
801:
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280:) to estimate the position of the vehicle. This may help to navigate submarines,
841:
646:
305:
291:
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85:, which works in the air and uses the same principles for wind speed profiling.
61:
164:
Underwater photo of an ADCP with five transducers (Model
Signature1000, Nortek)
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in the 1980s. The working frequencies range of ADCPs range from 38
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are required to sample the returning signal in order to determine the
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Head of an ADCP with four transducers (Model WH-600, RD Instruments)
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10.1175/1520-0426(1984)001<0293:PTPCDS>2.0.CO;2
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10.1175/1520-0426(1992)009<0149:RSCFIP>2.0.CO;2
276:. The sensor suite is combined (typically by use of a
432:"Acoustic doppler current profiler, US Patent 5615173"
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As any acoustical instrument, the ADCP contributes to
850:
787:
689:
587:
764:Ultra-short baseline acoustic positioning system
304:Some ADCPs can be configured to measure surface
488:Data analysis methods in physical oceanography
27:Meter used to measure water current velocities
565:
485:William J. Emery, Richard E. Thomson (2001).
450:Journal of Atmospheric and Oceanic Technology
396:Journal of Atmospheric and Oceanic Technology
8:
491:. Gulf Professional Publishing. p. 83.
125:, a clock to measure the traveling time, a
739:Short baseline acoustic positioning system
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558:
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729:Long baseline acoustic positioning system
461:
407:
383:
779:Underwater acoustic positioning system
657:Surveillance Towed Array Sensor System
370:in the ocean which may interfere with
197:. The instruments can also be used in
286:remotely operated underwater vehicles
149:at the instrument position using the
117:Further components of an ADCP are an
7:
534:"Icon Encyclopedia of Earth Topics"
323:Kolmogorov structure configuration
25:
774:Underwater acoustic communication
709:Acoustic Doppler current profiler
532:Hogan, C Michael (October 2011).
225:for the standard alkaline packs.
32:acoustic doppler current profiler
18:Acoustic Doppler Current Profiler
680:
832:Hearing range of marine mammals
145:sensor is used to estimate the
714:Acoustic seabed classification
1:
919:Oceanographic instrumentation
56:over a depth range using the
334:Advantages and disadvantages
205:to continuously measure the
217:from shore, using the same
131:analog-to-digital converter
945:
797:Acoustic survey in fishing
260:Doppler velocity log (DVL)
151:seawater equation of state
734:Ocean acoustic tomography
678:
193:The primary usage is for
837:Marine mammals and sonar
662:Synthetic aperture sonar
135:digital signal processor
719:Acoustical oceanography
637:Scientific echosounder
296:
246:Discharge measurements
165:
106:
98:
79:A similar device is a
929:Watercraft components
914:Physical oceanography
817:Deep scattering layer
627:Multibeam echosounder
622:GLORIA sidescan sonar
294:
223:lithium battery packs
163:
104:
96:
769:Underwater acoustics
759:Sound velocity probe
754:Sound speed gradient
672:Upward looking sonar
617:Fessenden oscillator
272:, and data from the
119:electronic amplifier
878:Hydrographic survey
827:Fisheries acoustics
807:Animal echolocation
602:Baffles (submarine)
521:. US Patent office.
274:acceleration sensor
873:Geophysical MASINT
858:Acoustic signature
297:
268:, compass or gyro
169:Processing methods
166:
127:temperature sensor
107:
99:
49:, used to measure
896:
895:
667:Towed array sonar
647:Sonar beamforming
632:Passive acoustics
498:978-0-444-50757-0
353:ocean circulation
300:Wave measurements
89:Working principle
16:(Redirected from
936:
789:Acoustic ecology
704:Acoustic release
699:Acoustic network
684:
597:Active acoustics
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691:Ocean acoustics
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642:Side-scan sonar
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368:noise pollution
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229:Bottom tracking
219:umbilical cable
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851:Related topics
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607:Bistatic sonar
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581:Hydroacoustics
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348:ocean currents
344:remote sensing
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147:sound velocity
109:ADCPs contain
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66:RD Instruments
58:Doppler effect
26:
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812:Beached whale
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749:SOFAR channel
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612:Echo sounding
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456:: 293. 1984.
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402:: 149. 1992.
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278:Kalman filter
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139:Doppler shift
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111:piezoelectric
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51:water current
48:
45:similar to a
44:
43:current meter
41:
40:hydroacoustic
37:
33:
19:
863:Bioacoustics
802:Acoustic tag
708:
538:. Retrieved
527:
513:
502:. Retrieved
487:
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399:
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386:
365:
363:deployment.
357:
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316:
303:
266:position fix
263:
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211:
195:oceanography
192:
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185:Applications
172:
116:
108:
80:
78:
35:
31:
29:
306:wave height
253:dot product
212:Mounted on
143:temperature
72:to several
62:sound waves
903:Categories
888:Soundscape
842:Whale song
822:Fishfinder
744:Sofar bomb
724:Hydrophone
540:2012-09-13
504:2011-02-06
379:References
340:biofouling
313:Turbulence
282:autonomous
179:narrowband
175:incoherent
54:velocities
883:Noise map
472:1520-0426
418:1520-0426
319:turbulent
207:discharge
74:megahertz
868:Biophony
652:Sonobuoy
372:cetacean
360:sidelobe
342:and the
214:moorings
155:salinity
123:receiver
270:heading
242:, etc.
38:) is a
495:
470:
416:
284:, and
203:canals
199:rivers
177:" or "
133:and a
909:Sonar
589:Sonar
328:buoys
82:SODAR
47:sonar
493:ISBN
468:ISSN
414:ISSN
240:gyro
201:and
141:. A
121:, a
36:ADCP
458:doi
404:doi
236:GPS
70:kHz
60:of
30:An
905::
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34:(
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
