Underwater echo detection systems were developed for the purpose of underwater navigation by submarines in World war I and in particular after the Titanic sank in 1912. when Leonardo da Vinci wrote about it. one month after the sinking of the Titanic. The first patent for an underwater echo ranging sonar was filed at the British Patent Office by English metereologist Lewis Richardson.HISTORY Humans were listening to underwater sounds with air tubes as early as 1490. . Alexander Belm in Vienna described an underwater echosounding device in the same year. It was not until the mid to late 1800's that the science developed to convert acoustic energy into electrical energy.
although it could not precisely determine its direction. . Powerful high frequency ultrasonic echo-sounding device was developed by emminent French physicist Paul Langévin and Russian scientist Constantin Chilowsky. The Fessenden sonar was an electromagnetic moving-coil oscillator that emitted a low-frequency noise and then switched to a receiver to listen for echoes. allowing powerful electronic amplifications necessary for developments in ultrasonic instruments. It was able to detect an iceberg underwater from 2 miles away.History… The first working sonar system was designed and built in the United States by Canadian Reginald Fessenden in 1914. The turn of the century also saw the invention of the Diode and the Triode.
The sound reflects off the seafloor and returns to the transducer.. etc. The word sounding is used for all types of depth measurements.ECHO SOUNDING Echo sounding is the technique of using sound pulses to find the depth of water. and preventing collisions with unseen underwater rocks. The time the sound takes to travel to the bottom and back is used to calculate the distance to the seafloor. Sound pulses are sent from the transducer straight down into the water. These sonar systems use a transducer that is usually mounted on the bottom of a ship. and is unrelated in origin to the word sound in the sense of noise or tones. reefs. The echo sounder is the most common system for measuring water depth. including those that don't use sound. .
ECHO SOUNDING DEVICES .
Amplifier – to amplify the weak electrical oscillations that has been generated by the receiving transducer on reception of the reflected sound vibration. . Recorder .for measuring and indicating depth. Pulse generator – to produce electrical oscillations for the transmitting transducer.ECHO SOUNDER COMPONENTS Basically an echo sounder has following components: Transducer – to generate the sound vibrations and also receive the reflected sound vibration.
ECHO SOUNDER COMPONENTS .
Illustration of echo sounding using a Echosounder .
This continuous depth data is used to create bathymetry maps of the survey area. The faster the sound pulses return to the transducer from the ocean floor.WORKING Water depth is estimated by using the speed of sound through the water (approximately 1.500 meters per second) and a simple calculation: Distance = speed x time/2 The product is divided by two because the measured time is the roundtrip time (from the transducer to the seafloor and back to the transducer). . which produces a line showing the depth of the ocean beneath the ship. The sound pulses are sent out regularly as the ship moves along the surface. Echo sounders calculate water depth by measuring the time it takes for the acoustic signal to reach the bottom and the echo to return to the ship. the shallower the water depth is and the higher the elevation of the sea floor.
Echo sounding used in a Ship .
mud. To special purpose or scientific surveys. the acoustic data collected has been valuable in underwater habitat assessment and classification for the variables. Variations in elevation often represent places where fish congregate.Common use As an aid to navigation (most larger vessels will have at least a simple depth sounder) Is commonly used for fishing.g. . sand) and submersed aquatic vegetation and algae . Used for the work of Hydrography. More recently. rock. seabed type (e.with the appropriate software.
portable. Scientific echo sounder equipment is built to exacting standards and tested to be stable and reliable in the transmission and receiving of sound energy under the water. further enhancing the reliability and precision with which these systems operate. This enables analysis and incorporation of the results into a Geographic Information System (GIS) for further analysis. Recent advances have led to the development of the digital scientific echo sounder.Developments Specially written software is available for analysis of hydro acoustic data for assessment of underwater physical and biological characteristics. . and relatively easy to use. Modern scientific echo sounders are reliable. correlation with other variables. Collected acoustic data is "stamped" with geographic information for precise positional information (coordinates and time). mapping. and display.
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