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93-461: The Tudor Hill Laboratory was the terminus for a number of undersea systems supporting both passive and active sonar development and environmental and oceanographic acoustical research with shore facilities also available to visiting researchers of Navy projects with suitable clearances and funding. The laboratory was the only Atlantic Navy research and development facility with direct access to an operational Sound Surveillance System (SOSUS) facility,

186-544: A navigation aid system developed, patented and produced by the Submarine Signal Company of Boston. The company produced submarine acoustic signals, first bells and receivers then transducers , as aids to navigation. The signals were fixed, associated with lights and other fixed aids, or installed aboard ships enabling warning of fixed hazards or signaling between ships. ATLAS-Werke , at the time Norddeutsche Maschinen und Armaturenfabrik, of Germany also manufactured

279-446: A helicopter pad. The design was intended to withstand a wave height of 70 feet (21.3 m), but in its early years the tower was damaged by waves approaching the design height. Typical minimum staffing by contract personnel was eight persons, including electronic technicians, mechanics and housekeeping staff. The prefabricated tower was designed, built and installed in 1960 by J. Ray McDermott & Company of New Orleans. In July 1966

372-411: A hydrophone/transducer receives a specific interrogation signal it responds by transmitting a specific reply signal. To measure distance, one transducer/projector transmits an interrogation signal and measures the time between this transmission and the receipt of the other transducer/hydrophone reply. The time difference, scaled by the speed of sound through water and divided by two, is the distance between

465-564: A method of acoustical communications. The oscillator accomplished that and led to further developments in underwater acoustics. The company acted quickly to replace the bells with the transducers and began working on their use in submarine telegraphy, but it was slow to recognize or take advantage of the sonic distance measurement of interest to Fessenden so that others took the lead in SOund NAvigation Ranging , now generally simply known as sonar. Submarine Signal Company's focus with

558-402: A microphone placed in a metal box filled with water and attached to a ship's skin from inside allowed clear reception. In further experiments placement of such microphones on each side of a ship allowed finding the direction of the source. Intensity on one side showed the source to that side of the ship and equal intensity showed the source to be directly ahead. A direction indicator box allowed

651-495: A narrow arc, although the beam may be rotated, relatively slowly, by mechanical scanning. Particularly when single frequency transmissions are used, the Doppler effect can be used to measure the radial speed of a target. The difference in frequency between the transmitted and received signal is measured and converted into a velocity. Since Doppler shifts can be introduced by either receiver or target motion, allowance has to be made for

744-487: A pulse to reception is measured and converted into a range using the known speed of sound. To measure the bearing , several hydrophones are used, and the set measures the relative arrival time to each, or with an array of hydrophones, by measuring the relative amplitude in beams formed through a process called beamforming . Use of an array reduces the spatial response so that to provide wide cover multibeam systems are used. The target signal (if present) together with noise

837-520: A steel tube, vacuum-filled with castor oil , and sealed. The tubes then were mounted in parallel arrays. The standard US Navy scanning sonar at the end of World War II operated at 18 kHz, using an array of ADP crystals. Desired longer range, however, required use of lower frequencies. The required dimensions were too big for ADP crystals, so in the early 1950s magnetostrictive and barium titanate piezoelectric systems were developed, but these had problems achieving uniform impedance characteristics, and

930-749: A submerged bell for experiments in Lake Geneva . Lucian I. Blake in association with the United States Lighthouse Service did similar work in 1883 using a submerged bell with the explicit purpose of using sound as an aid to navigation. Experiments in England and the United States occurred independently afterward. Reception problems related to ship noise were partially solved when A. J. Munday, who had worked with Dr. Elisha Gray on signaling by underwater bells to include actual messages, found that

1023-512: A system later tested in Boston Harbor, and finally in 1914 from the U.S. Revenue Cutter Miami on the Grand Banks off Newfoundland . In that test, Fessenden demonstrated depth sounding, underwater communications ( Morse code ) and echo ranging (detecting an iceberg at a 2-mile (3.2 km) range). The " Fessenden oscillator ", operated at about 500 Hz frequency, was unable to determine

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1116-565: A target ahead of the attacker and still in ASDIC contact. These allowed a single escort to make better aimed attacks on submarines. Developments during the war resulted in British ASDIC sets that used several different shapes of beam, continuously covering blind spots. Later, acoustic torpedoes were used. Early in World War II (September 1940), British ASDIC technology was transferred for free to

1209-484: A tripod mounted bell connected to a shore station by cable. A similar system of underwater bells mounted on ships enabled signaling between ships to avoid collisions in fog. The Cunard liner Lucania was equipped with the first ship-to-ship submarine signal device. The United States Lighthouse Board had some interest, but they did not take immediate action. The British Admiralty and Trinity House and, in Germany,

1302-674: A vessel's bow. The Submarine Signal Company, was established in Boston, Massachusetts, to turn the research into a navigational aid. The company developed, patented and began manufacturing electromechanical bell signals and shipboard receivers based on previous research, introducing the world's first electronic underwater acoustic navigation aid in 1901. The signal system was of particular importance for safe navigation in fog. Fog signals, horns and whistles, conducted by air were unreliable and erratic. Sonic signals through water were more reliable and had more range. Offshore hazards could be marked by

1395-413: Is bistatic operation . When more transmitters (or more receivers) are used, again spatially separated, it is multistatic operation . Most sonars are used monostatically with the same array often being used for transmission and reception. Active sonobuoy fields may be operated multistatically. Active sonar creates a pulse of sound, often called a "ping", and then listens for reflections ( echo ) of

1488-453: Is its zero aging characteristics; the crystal keeps its parameters even over prolonged storage. Another application was for acoustic homing torpedoes. Two pairs of directional hydrophones were mounted on the torpedo nose, in the horizontal and vertical plane; the difference signals from the pairs were used to steer the torpedo left-right and up-down. A countermeasure was developed: the targeted submarine discharged an effervescent chemical, and

1581-415: Is the source level , PL is the propagation loss (sometimes referred to as transmission loss ), TS is the target strength , NL is the noise level , AG is the array gain of the receiving array (sometimes approximated by its directivity index) and DT is the detection threshold . In reverberation-limited conditions at initial detection (neglecting array gain): where RL is the reverberation level , and

1674-427: Is then passed through various forms of signal processing , which for simple sonars may be just energy measurement. It is then presented to some form of decision device that calls the output either the required signal or noise. This decision device may be an operator with headphones or a display, or in more sophisticated sonars this function may be carried out by software. Further processes may be carried out to classify

1767-402: Is very low, several orders of magnitude less than the original signal. Even if the reflected signal was of the same power, the following example (using hypothetical values) shows the problem: Suppose a sonar system is capable of emitting a 10,000 W/m signal at 1 m, and detecting a 0.001 W/m  signal. At 100 m the signal will be 1 W/m (due to the inverse-square law ). If

1860-713: The Titanic disaster of 1912. The world's first patent for an underwater echo-ranging device was filed at the British Patent Office by English meteorologist Lewis Fry Richardson a month after the sinking of Titanic , and a German physicist Alexander Behm obtained a patent for an echo sounder in 1913. The Canadian engineer Reginald Fessenden , while working for the Submarine Signal Company in Boston , Massachusetts, built an experimental system beginning in 1912,

1953-534: The Fessenden oscillator , a transducer, after its invention by Reginald Fessenden with development starting in 1912 at the Submarine Signal Company. That transducer allowed both sending and receiving leading to major advances in both submarine signals and extension into submarine telegraphy and experiments with underwater telephone communication and eventually sonar. Ships, commercial or naval, equipped with submarine signaling capability had that equipment noted as one of

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2046-546: The North German Lloyd Steamship Company took more immediate notice of the potential and became pioneers in implementation both at signal stations and as shipboard receivers. The German company Norddeutsche Maschinen und Armaturenfabrik (1902), becoming Atlas Werke in 1911, manufactured the system under license from the Submarine Signal Company. Major lines were equipping it ships with the apparatus so that in 1905, Cunard announced its entire fleet would have

2139-452: The Royal Navy had five sets for different surface ship classes, and others for submarines, incorporated into a complete anti-submarine system. The effectiveness of early ASDIC was hampered by the use of the depth charge as an anti-submarine weapon. This required an attacking vessel to pass over a submerged contact before dropping charges over the stern, resulting in a loss of ASDIC contact in

2232-551: The hull or become flooded, the 60 Hz sound from the windings can be emitted from the submarine or ship. This can help to identify its nationality, as all European submarines and nearly every other nation's submarine have 50 Hz power systems. Intermittent sound sources (such as a wrench being dropped), called "transients," may also be detectable to passive sonar. Until fairly recently, an experienced, trained operator identified signals, but now computers may do this. Passive sonar systems may have large sonic databases , but

2325-488: The 1930s American engineers developed their own underwater sound-detection technology, and important discoveries were made, such as the existence of thermoclines and their effects on sound waves. Americans began to use the term SONAR for their systems, coined by Frederick Hunt to be the equivalent of RADAR . In 1917, the US Navy acquired J. Warren Horton 's services for the first time. On leave from Bell Labs , he served

2418-492: The 1970s, compounds of rare earths and iron were discovered with superior magnetomechanic properties, namely the Terfenol-D alloy. This made possible new designs, e.g. a hybrid magnetostrictive-piezoelectric transducer. The most recent of these improved magnetostrictive materials is Galfenol . Other types of transducers include variable-reluctance (or moving-armature, or electromagnetic) transducers, where magnetic force acts on

2511-458: The Admiralty archives. By 1918, Britain and France had built prototype active systems. The British tested their ASDIC on HMS  Antrim in 1920 and started production in 1922. The 6th Destroyer Flotilla had ASDIC-equipped vessels in 1923. An anti-submarine school HMS Osprey and a training flotilla of four vessels were established on Portland in 1924. By the outbreak of World War II ,

2604-674: The British Board of Invention and Research , Canadian physicist Robert William Boyle took on the active sound detection project with A. B. Wood , producing a prototype for testing in mid-1917. This work for the Anti-Submarine Division of the British Naval Staff was undertaken in utmost secrecy, and used quartz piezoelectric crystals to produce the world's first practical underwater active sound detection apparatus. To maintain secrecy, no mention of sound experimentation or quartz

2697-553: The Fessenden device was on submarine telegraphy, with a beginning in submarine telephones. With marine radio gaining usage, the expensive submarine version faded. Despite Fessenden's demonstration in June 1914 of the effectiveness of his device in telegraphy, that aspect faded and the "sensing" potential, first crudely applied to locating icebergs, became critical with World War I and submarine warfare. Full focus came to underwater acoustics and

2790-651: The French physicist Paul Langevin , working with a Russian immigrant electrical engineer Constantin Chilowsky, worked on the development of active sound devices for detecting submarines in 1915. Although piezoelectric and magnetostrictive transducers later superseded the electrostatic transducers they used, this work influenced future designs. Lightweight sound-sensitive plastic film and fibre optics have been used for hydrophones, while Terfenol-D and lead magnesium niobate (PMN) have been developed for projectors. In 1916, under

2883-553: The United States. Research on ASDIC and underwater sound was expanded in the UK and in the US. Many new types of military sound detection were developed. These included sonobuoys , first developed by the British in 1944 under the codename High Tea , dipping/dunking sonar and mine -detection sonar. This work formed the basis for post-war developments related to countering the nuclear submarine . During

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2976-488: The acoustic signal and when equipped with receivers on each side the ship could determine approximate direction from which the signal came. A ship-to-ship system was also produced allowing ships so equipped to detect each other and estimate direction in fog. The company collected data from ships including ranges at which the signals of specific stations were detected. The collected data formed an early base of ocean acoustical properties. The original bells were quickly replaced by

3069-471: The adjacent Naval Facility Bermuda , allowing studies and evaluation of operational hardware. Data from the laboratory's experimental sensors was originally sent from the tower terminals to the laboratory by cable until replaced by microwave link. The laboratory had assigned vessels to serve the tower and conduct research, including the R/V Erline , a 105 ft (32.0 m) former oil field crew boat. In 1964

3162-400: The apparatus after its experience with Lucania and Norddeutscher Lloyd liners Kaiser Wilhelm II , Kronprinz Wilhelm and Kaiser Wilhelm der Grosse were successfully using the system. An example of significant commercial advantage, being able to operate when other ships were fog bound, was a case in which the liner Kaiser Wilhelm II was able to enter harbor twenty-two hours before

3255-415: The area near the boat. When active sonar is used to measure the distance from the transducer to the bottom, it is known as echo sounding . Similar methods may be used looking upward for wave measurement. Active sonar is also used to measure distance through water between two sonar transducers or a combination of a hydrophone (underwater acoustic microphone) and projector (underwater acoustic speaker). When

3348-498: The attack had the advantage that the German acoustic torpedo was not effective against a warship travelling so slowly. A variation of the creeping attack was the "plaster" attack, in which three attacking ships working in a close line abreast were directed over the target by the directing ship. The new weapons to deal with the ASDIC blind spot were "ahead-throwing weapons", such as Hedgehogs and later Squids , which projected warheads at

3441-505: The beam pattern suffered. Barium titanate was then replaced with more stable lead zirconate titanate (PZT), and the frequency was lowered to 5 kHz. The US fleet used this material in the AN/SQS-23 sonar for several decades. The SQS-23 sonar first used magnetostrictive nickel transducers, but these weighed several tons, and nickel was expensive and considered a critical material; piezoelectric transducers were therefore substituted. The sonar

3534-469: The bearing of the iceberg due to the 3-metre wavelength and the small dimension of the transducer's radiating face (less than 1 ⁄ 3 wavelength in diameter). The ten Montreal -built British H-class submarines launched in 1915 were equipped with Fessenden oscillators. During World War I the need to detect submarines prompted more research into the use of sound. The British made early use of underwater listening devices called hydrophones , while

3627-444: The characteristics of the outgoing ping. For these reasons, active sonar is not frequently used by military submarines. A very directional, but low-efficiency, type of sonar (used by fisheries, military, and for port security) makes use of a complex nonlinear feature of water known as non-linear sonar, the virtual transducer being known as a parametric array . Project Artemis was an experimental research and development project in

3720-434: The depth charges had been released, the attacking ship left the immediate area at full speed. The directing ship then entered the target area and also released a pattern of depth charges. The low speed of the approach meant the submarine could not predict when depth charges were going to be released. Any evasive action was detected by the directing ship and steering orders to the attacking ship given accordingly. The low speed of

3813-492: The direction from which the signal came. The Submarine Signal Company, with branches in Bremen, Liverpool, London, and New York, was both manufacturing the apparatus and collecting data from shipping companies and individual ships on the operation of the signals. The utility of the signals became evident as more stations and ships were equipped. Prominent ship captains, such as James Watt, master of Lusitania , strongly endorsed

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3906-412: The echoes. Since the original signal is much more powerful, it can be detected many times further than twice the range of the sonar (as in the example). Active sonar have two performance limitations: due to noise and reverberation. In general, one or other of these will dominate, so that the two effects can be initially considered separately. In noise-limited conditions at initial detection: where SL

3999-456: The electro-acoustic transducers are of the Tonpilz type and their design may be optimised to achieve maximum efficiency over the widest bandwidth, in order to optimise performance of the overall system. Occasionally, the acoustic pulse may be created by other means, e.g. chemically using explosives, airguns or plasma sound sources. To measure the distance to an object, the time from transmission of

4092-427: The entire signal is reflected from a 10 m target, it will be at 0.001 W/m when it reaches the emitter, i.e. just detectable. However, the original signal will remain above 0.001 W/m until 3000 m. Any 10 m target between 100 and 3000 m using a similar or better system would be able to detect the pulse, but would not be detected by the emitter. The detectors must be very sensitive to pick up

4185-521: The equipment under license largely for the European market. The system used more reliable underwater sound to project acoustic signals from a shore station or an undersea hazard on which a signal was placed. The signals were usually associated with a lightvessel , a bell buoy or hung on a tripod frame on the sea floor connected to a shore stations by cable. At first the system depended on bells operated by electric strikers. Receivers aboard ships could detect

4278-529: The fog at the Weser river mouth cleared and other vessels could enter port. By using the submarine signals of the entrance lightvessel the ship was able to enter the fog clear harbor to discharge passengers and cargo. The Admiralty conducted tests in October 1906 using a bell such as was used by U.S. lightvessels. The tests were successful, with the Admiralty recommending their use as a coastal navigation aid with notes on

4371-500: The government as a technical expert, first at the experimental station at Nahant, Massachusetts , and later at US Naval Headquarters, in London , England. At Nahant he applied the newly developed vacuum tube , then associated with the formative stages of the field of applied science now known as electronics , to the detection of underwater signals. As a result, the carbon button microphone , which had been used in earlier detection equipment,

4464-476: The introduction of radar . Sonar may also be used for robot navigation, and sodar (an upward-looking in-air sonar) is used for atmospheric investigations. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low ( infrasonic ) to extremely high ( ultrasonic ). The study of underwater sound is known as underwater acoustics or hydroacoustics . The first recorded use of

4557-505: The largest individual sonar transducers ever. The advantage of metals is their high tensile strength and low input electrical impedance, but they have electrical losses and lower coupling coefficient than PZT, whose tensile strength can be increased by prestressing . Other materials were also tried; nonmetallic ferrites were promising for their low electrical conductivity resulting in low eddy current losses, Metglas offered high coupling coefficient, but they were inferior to PZT overall. In

4650-498: The late 1950s to mid 1960s to examine acoustic propagation and signal processing for a low-frequency active sonar system that might be used for ocean surveillance. A secondary objective was examination of engineering problems of fixed active bottom systems. The receiving array was located on the slope of Plantagnet Bank off Bermuda. The active source array was deployed from the converted World War II tanker USNS  Mission Capistrano . Elements of Artemis were used experimentally after

4743-404: The magnetostrictive unit was much more reliable. High losses to US merchant supply shipping early in World War II led to large scale high priority US research in the field, pursuing both improvements in magnetostrictive transducer parameters and Rochelle salt reliability. Ammonium dihydrogen phosphate (ADP), a superior alternative, was found as a replacement for Rochelle salt; the first application

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4836-417: The main experiment was terminated. This is an active sonar device that receives a specific stimulus and immediately (or with a delay) retransmits the received signal or a predetermined one. Transponders can be used to remotely activate or recover subsea equipment. A sonar target is small relative to the sphere , centred around the emitter, on which it is located. Therefore, the power of the reflected signal

4929-403: The moments leading up to attack. The hunter was effectively firing blind, during which time a submarine commander could take evasive action. This situation was remedied with new tactics and new weapons. The tactical improvements developed by Frederic John Walker included the creeping attack. Two anti-submarine ships were needed for this (usually sloops or corvettes). The "directing ship" tracked

5022-490: The ocean or floats on a taut line mooring at a constant depth of perhaps 100 m. They may also be used by submarines , AUVs , and floats such as the Argo float. Passive sonar listens without transmitting. It is often employed in military settings, although it is also used in science applications, e.g. , detecting fish for presence/absence studies in various aquatic environments – see also passive acoustics and passive radar . In

5115-403: The other factors are as before. An upward looking sonar (ULS) is a sonar device pointed upwards looking towards the surface of the sea. It is used for similar purposes as downward looking sonar, but has some unique applications such as measuring sea ice thickness, roughness and concentration, or measuring air entrainment from bubble plumes during rough seas. Often it is moored on the bottom of

5208-411: The possible ship-to-ship use to warn and establish direction of another ship in fog. There was also notation of use between submarines and "parent ships", with some of the submarine results withheld from publication as purely military in application. Experience of U.S. Navy battleships in fog off Nantucket Shoals proved the fleet could, under reduced speed, safely navigate and maintain formation by using

5301-650: The potential to detect submarines by sound, either passively or actively. The existing receivers, designed to detect intentional signals, proved unable to detect the incidental sounds of submarines. Harold J. W. Fay of Submarine Signal Company was invited to meet with the Chief, Bureau of Steam Engineering 20 March 1917 to discuss establishing an acoustical research station at East Point, Nahant, Massachusetts . Fay gave assurances property would be made available. As implemented, Submarine Signal Company would be joined by Western Electric Company and General Electric Company to work on

5394-546: The program was transferred to the Manager, Antisubmarine Warfare Project Office and technical responsibility transferred to the Naval Research Laboratory (NRL). The research program was suspended on 30 June 1970 with occasional daytime inspections and maintenance work by NRL personnel. On 13 May 1976 the tower was toppled by demolition charges after which Erline conducted a fine grain grid survey to confirm no portion of

5487-699: The project. On 8–9 May, representatives of the companies met in Washington to establish working relationships. To meet concerns of the Naval Consulting Board that naval interests might not be met in general research, a Navy Special Board on Anti-Submarine Devices would oversee the work. Commander Clyde Stanley McDowell was secretary of the board and later filled the same function at the Naval Experimental Station, New London, Connecticut . The Nahant Antisubmarine Laboratory, completed April 7, 1917,

5580-402: The projectors consisted of two rectangular identical independent units in a cast-iron rectangular body about 16 by 9 inches (410 mm × 230 mm). The exposed area was half the wavelength wide and three wavelengths high. The magnetostrictive cores were made from 4 mm stampings of nickel, and later of an iron-aluminium alloy with aluminium content between 12.7% and 12.9%. The power

5673-410: The pulse. This pulse of sound is generally created electronically using a sonar projector consisting of a signal generator, power amplifier and electro-acoustic transducer/array. A transducer is a device that can transmit and receive acoustic signals ("pings"). A beamformer is usually employed to concentrate the acoustic power into a beam, which may be swept to cover the required search angles. Generally,

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5766-456: The radial speed of the searching platform. One useful small sonar is similar in appearance to a waterproof flashlight. The head is pointed into the water, a button is pressed, and the device displays the distance to the target. Another variant is a " fishfinder " that shows a small display with shoals of fish. Some civilian sonars (which are not designed for stealth) approach active military sonars in capability, with three-dimensional displays of

5859-410: The selection of receivers individually for comparison of signal strength for direction. Experiments determined modifications to bells used in air that optimized them for underwater use. Electrical striking systems allowed the bells to be connected to surface aids. Canadian experiments showed the practicality of determining direction by comparison of the reception by two receivers mounted on each side of

5952-405: The ship's navigation capabilities in registry information from the first decade of the century until nearly mid century. In 1907 the information was important to insurance underwriters and American Bureau of Shipping required that ships so equipped by indicated by the note "Sub. Sig." in ship's registry information. Commercial lines advertised the capability as a safety measure. Submarine signaling

6045-562: The signal without use of stopwatches. The radio dots would follow a bell strike sequence and the number of dots received before the next bell signal would indicate the distance in half miles. The stations with the capability and precise method to use the combined radio, including stations transmitting radio direction finding signals, and submarine signal were published in nautical notices and tables. The Fessenden oscillator, invented by Submarine Signal Company's consulting engineer Reginald Fessenden in 1913 and developed and manufactured in 1914,

6138-409: The signals. On March 3, 1905, an act in the United States had authorized funding for aids including submarine signals. The U.S. lighthouse authorities were by the summer of 1906 installing signals, specifically at lightvessels stationed at Boston, Pollock Rip, Nantucket, Fire Island, and Sandy Hook. The United States and Canada were placing the signals at important locations. The U.S. Lighthouse Board

6231-425: The sonar operator usually finally classifies the signals manually. A computer system frequently uses these databases to identify classes of ships, actions (i.e. the speed of a ship, or the type of weapon released and the most effective countermeasures to employ), and even particular ships. Submarine signals Submarine signals had a specific, even proprietary, meaning in the early 20th century. It applied to

6324-408: The surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: passive sonar means listening for the sound made by vessels; active sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before

6417-437: The surfaces of gaps, and moving coil (or electrodynamic) transducers, similar to conventional speakers; the latter are used in underwater sound calibration, due to their very low resonance frequencies and flat broadband characteristics above them. Active sonar uses a sound transmitter (or projector) and a receiver. When the two are in the same place it is monostatic operation . When the transmitter and receiver are separated it

6510-414: The system. Marine underwriters needed information on which ships were equipped to adjust risk for vessel and cargo insurance. The American Bureau of Shipping included whether a vessel was equipped with submarine signal apparatus as a part of the registry information along with wireless. Registers making note of navigation equipment of yachts and ships listed "Submarine Signal system" or "Sub.Sig." as seen in

6603-600: The target and localise it, as well as measuring its velocity. The pulse may be at constant frequency or a chirp of changing frequency (to allow pulse compression on reception). Simple sonars generally use the former with a filter wide enough to cover possible Doppler changes due to target movement, while more complex ones generally include the latter technique. Since digital processing became available pulse compression has usually been implemented using digital correlation techniques. Military sonars often have multiple beams to provide all-round cover while simple ones only cover

6696-405: The target submarine on ASDIC from a position about 1500 to 2000 yards behind the submarine. The second ship, with her ASDIC turned off and running at 5 knots, started an attack from a position between the directing ship and the target. This attack was controlled by radio telephone from the directing ship, based on their ASDIC and the range (by rangefinder) and bearing of the attacking ship. As soon as

6789-556: The technique was in 1490 by Leonardo da Vinci , who used a tube inserted into the water to detect vessels by ear. It was developed during World War I to counter the growing threat of submarine warfare , with an operational passive sonar system in use by 1918. Modern active sonar systems use an acoustic transducer to generate a sound wave which is reflected from target objects. Although some animals ( dolphins , bats , some shrews , and others) have used sound for communication and object detection for millions of years, use by humans in

6882-458: The torpedo went after the noisier fizzy decoy. The counter-countermeasure was a torpedo with active sonar – a transducer was added to the torpedo nose, and the microphones were listening for its reflected periodic tone bursts. The transducers comprised identical rectangular crystal plates arranged to diamond-shaped areas in staggered rows. Passive sonar arrays for submarines were developed from ADP crystals. Several crystal assemblies were arranged in

6975-443: The tower remained above the 100 ft (30.5 m) level. On 12 June a Notice to Mariners noted it as an obstruction covered by 16 fathoms (29.3 m). Sonar Sonar ( sound navigation and ranging or sonic navigation and ranging ) is a technique that uses sound propagation (usually underwater, as in submarine navigation ) to navigate , measure distances ( ranging ), communicate with or detect objects on or under

7068-453: The tower was used to support the Navy's Sea Lab I . The tower was supported before Erline's acquisition in 1967 by MAC III . The support included regular supply of JP-5 fuel for the tower's diesels brought in 500 US gallons (1,900 L) bladders. The tower was four-legged with a two-story platform for crew quarters, instrumentation and support services. The tower had fuel storage, crane and

7161-409: The two platforms. This technique, when used with multiple transducers/hydrophones/projectors, can calculate the relative positions of static and moving objects in water. In combat situations, an active pulse can be detected by an enemy and will reveal a submarine's position at twice the maximum distance that the submarine can itself detect a contact and give clues as to the submarine's identity based on

7254-481: The very broadest usage, this term can encompass virtually any analytical technique involving remotely generated sound, though it is usually restricted to techniques applied in an aquatic environment. Passive sonar has a wide variety of techniques for identifying the source of a detected sound. For example, U.S. vessels usually operate 60 Hertz (Hz) alternating current power systems. If transformers or generators are mounted without proper vibration insulation from

7347-436: The water was initially recorded by Leonardo da Vinci in 1490: a tube inserted into the water was said to be used to detect vessels by placing an ear to the tube. In the late 19th century, an underwater bell was used as an ancillary to lighthouses or lightships to provide warning of hazards. The use of sound to "echo-locate" underwater in the same way as bats use sound for aerial navigation seems to have been prompted by

7440-464: The yacht Noma and Lloyd's Register , column two, "Special surveys" for ships. The Submarine Signal Company was the first company engaged in underwater acoustics , becoming the national underwater sound experts and producing acoustical aids to navigation. It also became the major sonar supplier to the U.S. Navy in later years. A technique termed "synchronous signaling" combined bell signals with coordinated radio dot signals for direct distance to

7533-403: Was a transducer that was easier to install and maintain, could both send and receive, and also allowed coded communication between any two installations, including submarines. Bells were quickly phased out and transducer equipped installations remained active until World War II. The bells had been adequate to send signals, even coded strikes for identification, but the company had been seeking

7626-465: Was a large array of 432 individual transducers. At first, the transducers were unreliable, showing mechanical and electrical failures and deteriorating soon after installation; they were also produced by several vendors, had different designs, and their characteristics were different enough to impair the array's performance. The policy to allow repair of individual transducers was then sacrificed, and "expendable modular design", sealed non-repairable modules,

7719-559: Was a replacement of the 24 kHz Rochelle-salt transducers. Within nine months, Rochelle salt was obsolete. The ADP manufacturing facility grew from few dozen personnel in early 1940 to several thousands in 1942. One of the earliest application of ADP crystals were hydrophones for acoustic mines ; the crystals were specified for low-frequency cutoff at 5 Hz, withstanding mechanical shock for deployment from aircraft from 3,000 m (10,000 ft), and ability to survive neighbouring mine explosions. One of key features of ADP reliability

7812-406: Was almost out of the water, thus reducing the effectiveness and requiring a solution by the Submarine Signal Company. By 1907, the signals were in common use, with most large ships equipped with the receiving apparatus. The receiving apparatus had evolved from a simple receiver on the ship's bottom to two hydrophones in water-filled sea chests on each side of the ship, enabling the ship to determine

7905-531: Was being loaded on the cable-laying vessel, World War I ended and Horton returned home. During World War II, he continued to develop sonar systems that could detect submarines, mines, and torpedoes. He published Fundamentals of Sonar in 1957 as chief research consultant at the US Navy Underwater Sound Laboratory . He held this position until 1959 when he became technical director, a position he held until mandatory retirement in 1963. There

7998-669: Was chosen instead, eliminating the problem with seals and other extraneous mechanical parts. The Imperial Japanese Navy at the onset of World War II used projectors based on quartz . These were big and heavy, especially if designed for lower frequencies; the one for Type 91 set, operating at 9 kHz, had a diameter of 30 inches (760 mm) and was driven by an oscillator with 5 kW power and 7 kV of output amplitude. The Type 93 projectors consisted of solid sandwiches of quartz, assembled into spherical cast iron bodies. The Type 93 sonars were later replaced with Type 3, which followed German design and used magnetostrictive projectors;

8091-426: Was little progress in US sonar from 1915 to 1940. In 1940, US sonars typically consisted of a magnetostrictive transducer and an array of nickel tubes connected to a 1-foot-diameter steel plate attached back-to-back to a Rochelle salt crystal in a spherical housing. This assembly penetrated the ship hull and was manually rotated to the desired angle. The piezoelectric Rochelle salt crystal had better parameters, but

8184-474: Was made obsolescent and overtaken by advances during World War II. In 1946 the Submarine Signal Company was acquired by and merged with Raytheon , becoming Raytheon's Marine Division, after having become the national leader in underwater sound, sonar and other work with the Navy during the World Wars and branching into other marine systems. In 1826 Jean-Daniel Colladon and Jacques Charles François Sturm used

8277-593: Was made – the word used to describe the early work ("supersonics") was changed to "ASD"ics, and the quartz material to "ASD"ivite: "ASD" for "Anti-Submarine Division", hence the British acronym ASDIC . In 1939, in response to a question from the Oxford English Dictionary , the Admiralty made up the story that it stood for "Allied Submarine Detection Investigation Committee", and this is still widely believed, though no committee bearing this name has been found in

8370-586: Was ordering systems for the Gulf of Mexico and Britain had adopted the system for all its aids to navigation. In 1910, the report of the United States Department of Commerce showed forty-nine signals established by June 30, most on lightvessels. Extension into the Great Lakes revealed a problem with the forepeak receiver installation for seagoing ships operated in light condition in fresh water. The forepeak

8463-567: Was provided from a 2 kW at 3.8 kV, with polarization from a 20 V, 8 A DC source. The passive hydrophones of the Imperial Japanese Navy were based on moving-coil design, Rochelle salt piezo transducers, and carbon microphones . Magnetostrictive transducers were pursued after World War II as an alternative to piezoelectric ones. Nickel scroll-wound ring transducers were used for high-power low-frequency operations, with size up to 13 feet (4.0 m) in diameter, probably

8556-507: Was replaced by the precursor of the modern hydrophone . Also during this period, he experimented with methods for towing detection. This was due to the increased sensitivity of his device. The principles are still used in modern towed sonar systems. To meet the defense needs of Great Britain, he was sent to England to install in the Irish Sea bottom-mounted hydrophones connected to a shore listening post by submarine cable. While this equipment

8649-430: Was the first anti-submarine acoustical laboratory of the Navy. The laboratory, a cluster of buildings behind guarded security fencing, was where "submarine signals" research entered the new field of anti-submarine acoustics. The submarine signals as navigational aids, just as many lights went dark, were stopped so as not to aid enemy submarines or become gathering points for target ships. During World War I and after,

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