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Topic: Echo sounding

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	NAVAL SONAR - Chapter 15
		A sound is transmitted vertically downward, and the time that is necessary for the sound to travel to the bottom and return to the surface is recorded.
		The interval between the emission of the signal and the return of the echo is timed (1) by rotating a disk at a known constant speed and (2) by noting the angular rotation of the disk during the interval by reference to a scale graduated to read directly in fathoms.
		In normal sounding, the echo is picked up by the receiver element and, after passing through the amplifier, is led to the stylus assembly in the form of high-frequency alternating current at about 300 volts.
	www.hnsa.org /doc/sonar/chap15.htm (4033 words)

	AllRefer.com - echo sounder (Geology And Oceanography) - Encyclopedia
		Echo sounding is based on the principle that water is an excellent medium for the transmission of sound waves and that a sound pulse will bounce off a reflecting layer, returning to its source as an echo.
		The time interval between the initiation of a sound pulse and echo returned from the bottom can be used to determine the depth of the bottom.
		Sea Beam employs an array of sound transducers across the hull of the survey vessel which radiate sound in a swathe, thereby allowing a wide region of the seafloor to be mapped.
	reference.allrefer.com /encyclopedia/E/echosoun.html (416 words)

	Echo - Wikipedia, the free encyclopedia
		Light echo, a visual phenomenon seen when light from a rapidly brightening object such as a nova is reflected from interstellar matter.
		Echo I or Echo II, classes of Soviet submarines.
		The Echo (Irish Newspaper) a regional newspaper in Dublin, Ireland.
	en.wikipedia.org /wiki/Echo (335 words)

	Dive and Discover : Sonar : Echo Sounding
		Echo sounding is the key method scientists use to map the seafloor today.
		The faster the sound waves return, the smaller the water depths and the higher the elevation of the seafloor.
		Echo sounders repeatedly “ping” the seafloor as a ship moves along the surface, producing a continuous line showing ocean depths directly beneath the ship.
	www.divediscover.whoi.edu /tools/sonar-singlebeam.html (351 words)

	Ultrasound and Medical Imaging (Site not responding. Last check: 2007-10-19)
		Sound is normally associated with human ears and the sense of hearing.
		A sound pulse is sent by a transmitter through the water, and its echo is received by a detector after a short interval of time.
		From the time of each echo’s return and the known speed of sound in tissue (1,540m/s or 5,005ft/s), the distances of the different parts of the organ of interest from the machine is determined.
	mason.gmu.edu /~mnguyena/Ultrasound2.htm (1375 words)

	NOAA Ocean Explorer: Echo Sounding Reading
		Echoes, which are made by sounds reflected back to you, are heard on all sides and by everybody, you are so used to hearing them that they are seldom noticed unless the echo is heard at a considerable time interval after the sound is produced.
		But he did succeed in getting echoes from the bottom of the ocean, which was perhaps more important, for the sea always has a bottom while you can’t find icebergs on every little summer’s outing at sea.
		While you get echoes so easily in air you will be surprised to know that you can hear them more easily in water, for sound travels better in water than in air, travels faster and farther.
	oceanexplorer.noaa.gov /library/readings/echosounding/echosounding.html (2038 words)

	Echo sounding: Notes
		Because of the importance of the sound velocity, tables are constructed for different parts of the ocean (known as Matthew's tables) of sound velocity vs. depth.
		These early echo sounding systems were incomparably better than the weight and line approach, and depth measurements were made more or less continuously as ships steamed along.
		Many of these sound transmitters sent sound out in a 60 degree cone from the the ship, and echos were received from all along the bottom from that cone.
	www.geology.ucdavis.edu /~gel150b/echos.html (2160 words)

	NOAA Ocean Explorer: History: Age of Electronics (1923-1945)
		These early echo sounders led to many discoveries as CandGS ships began systematic surveys of the continental shelves and slopes of the United States and in the waters of the northeast Pacific Ocean.
		RAR led to advances in the understanding of sound in seawater, and gave a first glimpse of the potential for transmitting sound throughout oceanic basins.
		Early magnetometers, scanning sonars for submarine detection, and acoustic sounding instruments all led to a greater understanding of the oceans and the sea floor.
	oceanexplorer.noaa.gov /history/electronic/electronic.html (1298 words)

	Echo Sounder: Technology Gallery for Discovery of Sound in the Sea (Site not responding. Last check: 2007-10-19)
		Sound pulses are sent from the transducer straight down into the water.
		The faster the sound pulses return to the transducer from the ocean floor, the shallower the water depth is and the higher the elevation of the sea floor.
		The sound pulses are sent out regularly as the ship moves along the surface, which produces a line showing the depth of the ocean beneath the ship.
	www.dosits.org /gallery/tech/osf/es1.htm (256 words)

	Multibeam echo-sounding sonars (Site not responding. Last check: 2007-10-19)
		In addition to soundings, the system calculates an acoustic image of the seabed, which is similar to a sidescan sonar image.
		The SVP25 is a self-recording sound velocity probe capable of measuring sound velocity from the surface down to 2000 m.
		Sound velocity data are stored in the probe and then downloaded to a PC onboard (to the SeaBat 6042 computer in our case).
	www.ocean.cf.ac.uk /people/neil/jrei/multibeams.html (1182 words)

	echo sounder - HighBeam Encyclopedia
		echo sounder an older instrumentation system for indirectly determining ocean floor depth.
		Global IP Sound releases industry's first acoustic echo suppression optimized for VoIP communications using PDAs.
		NMS Communications is offering its advanced echo cancellation DSP software and its Studio Sound software as stand-alone products.
	www.encyclopedia.com /doc/1E1-echosoun.html (509 words)

	NAVAL SONAR - Chapter 14
		During the time required for sound of a particular frequency to reach the target and to return as an echo, the frequency of the projected sound decreases.
		The longer the travel time, the greater is the decrease and the greater is the difference in frequency between the echo and the sound being radiated as the echo arrives.
		The QLA sonar receiver mixes the echo with the signal that is being transmitted and produces a beat frequency equal to the difference in frequency between the echo and the transmitted signal.
	www.hnsa.org /doc/sonar/chap14.htm (2705 words)

	Sounding Board - People news
		This can take extreme and even amusing forms, like an acquaintance of mine from South Africa who lived in Germany for 14 months and spent much of her time dressed in kaftans and with her hair braided — an effect made incongruous by the fact that, like myself, she was of European descent.
		Perhaps even more so for The Echo, which must be both the journal of the expatriate community and a bridge to all of Bulgaria.
		Sounding Board is a weekly guest column for members of Bulgaria’s expatriate community to voice their opinions or recount stories from their life in Bulgaria.
	www.sofiaecho.com /article/sounding-board/id_3535/catid_30 (879 words)

	Radio echo sounding (Site not responding. Last check: 2007-10-19)
		Ice sounding radar or radio echo sounding (RES) is the method of using pulses of radio frequency energy to measure ice thickness, obtain information about the nature of the underlying terrain and the bulk properties of the ice column.
		The origins of RES can be traced back to the early 1930's, where aircraft pilots noticed that when using the then newly developed radar altimeters in the polar regions the surface echos were corrupted by echos from the bottom of glaciers.
		To date the deepest ice sounded by the aircraft system is 3.5 km and information on the nature and texture of the basal surface can be obtained from the strength of the return echo.
	www.antarctica.ac.uk /Resources1/GSD/gsd_res.html (353 words)

	Alaska Ocean Observing System - Prince William Sound
		Some standard techniques to probe the ocean floor are echo sounding, multi-beam sonar, sidescan sonar, seismic reflection, seismic refraction and satellite altimetry.
		Bathymetric maps are generated by use of an echo sounder which measures the depth of the sea floor.
		The echo sounder consists of a transducer (sound transmitter) located under the hull of a vessel.
	ak.aoos.org /research_bath.html (455 words)

	Process for setting the transmission frequency of a distance measuring instrument operating according to the ...
		A process according to claim 1, wherein a mean noise amplitude of the received signals is determined and a difference between the amplitude-time-profile of the received signals and the mean noise amplitude is integrated.
		A process according to claim 3, wherein the mean noise amplitude is determined by forming the amplitude-time-profile formed of the received signals during a receiving spell prior to which no emission of a sonic or ultrasonic pulse has occurred.
		An evaluation circuit 34 is connected to the profile memory 32, and serves to recognise the output echo reflected by the target object 20 within the amplitude-time-profile stored in the profile memory 32, to determine the travelling time of the output echo, and to calculate the distance of the target object from this travelling time.
	www.freepatentsonline.com /5511041.html (3466 words)

	GEBCO Guidelines HTML Form
		Soundings the positions of which are doubtful (PD) or approximate (PA), or the existence of which is doubtful (ED), or where no bottom has been found, shall not be included.
		Because the volume of data derived from multibeam echo sounding are orders of magnitude larger than that derived from single beam echo sounding, it is necessary to subdivide the data into units of storage and exchange that are manageable in size and quantity, e.g., between 1 and 10 megabytes.
		While the wide variety of multibeam echo sounding systems precludes a practicable, single, fixed-field format structure, the initial metadata should fully document the byte order of multibyte integer fields, format or formats used, their contents, and any conditional flags or values by which specific formats are used or selected.
	www.ngdc.noaa.gov /mgg/gebco/gebcoguidehtml.html (14444 words)

	Radio-Echo Sounding of Ice Sheets and Glaciers I - Cryosphere [C]
		Airborne radar sounding is a powerful and well-known technique for studying ice sheets and glaciers and their contiguous underlying environments.
		Subglacial echoes are influenced by the physical properties of the interface such as the composition and roughness of the materials at the interface.
		The along-track offset from the radar to the scattering center indicates the extent of echo sources, thus relating to scattering from the subglacial interface.
	www.agu.org /meetings/fm04/fm04-sessions/fm04_C41D.html (3037 words)

	Submarine Sonar Operator's Manual - Chapter 5
		In the receiver-amplifier, the small electric current is strengthened and changed so that it is heard as sound in the phones or speaker.
		The remaining parts of the WCA are concerned with echo-ranging or depth sounding.
		If the sound is of equal loudness over a wide are, adjust tuning, gain, and filters to narrow it enough to give a distinct maximum.
	www.maritime.org /fleetsub/sonar/chap5.htm (2345 words)

	NOAA History - Tools of the Trade/Surveying and Mapping/Sounding Pole to Sea Beam
		In 1919, the French obtained sonic soundings in 60 meters depth from an underway vessel at 10 knots.
		An operator with earphones listening for the return signal transmitted a sound signal through the water at the precise instant the return echo was heard.
		Concurrent with improvements in recording devices were improvements in the sound projectors and receivers used for echo sounding.
	www.history.noaa.gov /stories_tales/poletobeam2.html (2907 words)

	Mars Deep Water Sounding Workshop (Site not responding. Last check: 2007-10-19)
		The Mars Deep Water Sounding workshop was held at NASA Ames Research Center on January 28,1998.
		Electromagnetic sounding is plausible, but studies are needed to determine the radar penetration characteristics in Mars analog materials.
		Using the Lake Vostok study as a direct analog, the method considered "most likely to succeed" by terrestrial geophysicists is a radar sounding of an aquifer under the Mars polar caps.
	astrobiology.arc.nasa.gov /workshops/1998/marswater (872 words)

	The application of remote sensing technology to marine fisheries: an introductory manual
		By analyzing the echo recording of the bottom, the general characteristics of the continental shelf of Sri Lanka were found to be “even flat” with an “uneven” and “very rough” outer edge.
		Although no detailed quantitative analysis of the echo- recording was made, it was possible to differentiate echo-traces to three arbitrary types regarding fish biomass: very scattered (1–10 mm per nautical mile), scattered (11–20 mm per nautical mile) and dense (greater than 20 mm per nautical mile).
		Figure 8.6 Dimensions of the sound beam form the echo sounder at 20 m echo depth in relation to the distance between trawl doors and wind ends of the trawl net.
	www.fao.org /DOCREP/003/T0355E/T0355E08.HTM (9820 words)

	Chelsea Technologies Group - Acoustic Transducers - Echo Sounder
		Chelsea Technologies Group manufacture a complete range of echo sounder transducers, which can be used either as stand alone acoustic transmitter/receivers or as part of a complete OEM package.
		The range of echo sounder transducers available covers the complete spectrum of possibilities from high power deep ranging echo sounder transducers to very high frequency fine detail transducers.
		CTG 1255 is a miniaturised echo sounder transducer, designed to work in high pressure, harsh environments.
	www.chelsea.co.uk /TransducersEchoSounder.htm (340 words)

	Echo Sounder-Multibeam: Technology Gallery for Discovery of Sound in the Sea (Site not responding. Last check: 2007-10-19)
		Multibeam bathymetry sonar is the relatively recent successor to echo sounding.
		On the left is a single beam echo sounder, which only images a circle of the seafloor (in red).
		On the right is a multibeam echo sounder that observes a much larger portion of the seafloor (line in red).
	www.dosits.org /gallery/tech/osf/esm1.htm (387 words)

	Technology: Standard/Multi-Frequency Echo Sounders: Observing and Counting, "Investigating Marine Life", Census of ... (Site not responding. Last check: 2007-10-19)
		Echo sounders may also be used for species identification.
		The towed body housing the echo sounder used for the observation of fish and plankton, even at great depths.
		A diagram demonstrating the greatly increased coverage effectiveness of multi beam (right) versus single beam (left) echo sounding.
	www.coml.org /edu/tech/count/echosoun1.htm (137 words)

	Hunting - Glossary - Discover The Outdoors (Site not responding. Last check: 2007-10-19)
		The determination of distance by measuring the time interval between transmission of a radiant energy signal (sound) and the return of its echo.
		An instrument for determining the depth of water by measuring the time of travel of a sound-pulse from the surface of a body of water to the bottom and back.
		Determination of the depth of water by measuring the time interval between emission of a sonic or ultrasonic signal and the return of its echo from the bottom.
	www.dto.com /hunting/glossary/index.jsp?startwith=e (2601 words)

	Earthguide animated diagram - Sonar-based mapping methods - Echo-sounding, Multibeam, Side-scan sonar, Seismic ... (Site not responding. Last check: 2007-10-19)
		Sonar is the basis of several methods used to map the seafloor.
		Sonar works by measuring the time it takes for sound waves to travel to an interface, reflect and return to a receiver located near the point of origin.
		Knowing the elapsed time and the speed at which the sound traveled allows the distance traveled to be calculated with precision.
	earthguide.ucsd.edu /earthguide/diagrams/sonar/sonar.html (134 words)

	Quarterdeck (6.3) Online -- Texas A&M Oceanography
		Because we know the speed of sound in water (usually 1,500 meters per second), that round-trip time can be used to calculate depth.
		With the echo sounder, scientists can measure the ocean's depth in a matter of seconds while the ship is moving -- an improvement on the ropes and weights technique, which took hours stopped in the ocean.
		The echo sounder enabled ships to routinely make thousands of depth measurements while crossing the oceans, and it became possible to make modern bathymetry (ocean depth) charts.
	www-ocean.tamu.edu /Quarterdeck/1998/3/sager-2.html (288 words)

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