Knowledge base
The standards GOST (ГОСТ) and other normative materials
Below is a list of various regulatory documents (GOST, OST, regulations) relating to navigation, cartography, GIS, hydrographic works.
Geographical information systems
GOST R 50828-95 Geoinformation mapping. Spatial data, digital and electronic maps. General requirements.
GOST R 51353-99 Geoinformation mapping. Metadata of electronic maps. Composition and content.
GOST R 52055-2003 Geoinformation mapping. The spatial terrain models. General requirements. GOST R 52155-2003 Geographic information systems Federal, regional, municipal. General technical requirements.
GOST R ISO 19105-2003 Geographic information. Compliance and testing (equivalent to the international standard ISO 19105-2000 Geographic information - Conformance and testing)
GOST R ISO 19113-2003 Geographic information. Principles of quality assessment (equivalent to international standard ISO 19113-2002 Geographic information - Quality principles)
GOST 52438-2005 Geographic information systems. Terms and definitions.
GOST 52571-2006 Geographic information system. Interoperability of spatial data. General requirements.
GOST 52572-2006 Geographic information systems. The coordinate basis. General requirements.
GOST R 52293-2004 Geoinformation mapping. A system of electronic maps. Electronic topographic maps. General requirements. Coordinate systems and navigation. About navigation activities
Federal law of the Russian Federation of February 14, 2009. N 22-ФЗ
GOST 19156-79 Ground-based navigation odometric equipment. Terms and definitions.
GOST R 51794-2001 Radio navigation equipment of the global navigation satellite system and the global positioning system. Coordinate systems. Methods of transformation of coordinates of defined points.
GOST R 51794-2008 Global navigation satellite systems. Coordinate systems. Methods of transformation of coordinates of defined points. System of geodetic parameters of the earth "Earth parameters 1990 " (EP-90)
Galazin V. F., Kaplan B. L., Lebedev M. G., Maksimov V. G., Petrov N. V., Sidorova-Biryukova T. L. / ed. khvostova V. V. - M. Coordination scientific information center, 1998. Resolution Of the government of the Russian Federation " On approval of the Rules for establishing local coordinate systems"
from March 3, 2007 N 139 the Resolution Of the government of the Russian Federation "About establishment of uniform state systems of coordinates"
from July 28, 2000 n 568 GOST R 52454-2005 Global navigation satellite system and global positioning system. Personal receiver. Specifications.
GOST R 52455-2005 Global navigation satellite system and global positioning system. Marine Receiver for General use. Specifications
GOST R 52456-2005 Global navigation satellite system and global positioning system. Marine Receiver for General use. Individual Receiver for automotive transport. Specifications
GOST R 52457-2005 Global navigation satellite system. Users equipment. Classification
GOST R 52865-2007 Global navigation satellite system. Parameters of the radio navigation field. Technical requirements and test methods
GOST R 52866-2007 Global navigation satellite system. Control and correction local station for civil purposes. Technical requirements
GOST R 52928-2008 Global satellite navigation system. Terms and definitions
International designations on maps
The main international designations and abbreviations used on marine and bathymetric maps are given.
|
|
A |
|
Aero |
Aeronautical |
Aero RC |
Aeronautical radiobeacon |
AIS |
Automatic Identification System |
Al |
Alternating |
ALC |
Articulated Loading Column |
Am |
Amber |
ASL |
Archipelagic Sea Lane |
B |
|
B |
Black |
Bk |
Broken |
Bn |
Beacon |
Bn |
Beacon Tower |
Bo |
Boulder(s) |
Br |
Breakers |
Bu |
Blue |
C |
|
C |
Coarse |
Ca |
Calcareous |
CALM |
Catenary Anchor Leg Mooring |
Cb |
Cobbles |
Cd |
Candela |
CG |
Coastguard |
Ch |
Church |
Chy |
Chimney |
cm |
Centimetre(s) |
Co |
Coral, Coralline algae |
Consol |
Consol beacon |
Cy |
Clay |
D |
|
DGPS |
Differential Global Positioning System |
Dia |
Diaphone |
Dir |
Direction light |
dm |
Decimetre(s) |
Dn, Dns |
Dolphin(s) |
DW |
Deep Water track, Deep Water route |
DWT |
Deadweight tonnage |
DZ |
Danger Zone |
E |
|
E |
East |
ED |
Existence doubtful |
Explos |
Explosive |
exting |
Extinguished |
F |
|
f |
Fine |
F |
Fixed |
FFl |
Fixed and flashing |
Fl |
Flashing |
Fla |
Flare stack |
Fog Det Lt |
Fog detector light |
FS |
Flagstaff, Flagpole |
Ft |
Foot/feet |
G |
|
G |
Gravel |
G |
Green |
GPS |
Global Positioning System |
GRT |
Gross Register Tonnage |
GT |
Gross tonnage |
H |
|
h |
Hard |
h |
Hour |
H |
Helicopter |
Hor |
Horizontally disposed |
I |
|
INT |
International |
Intens |
Intensified |
IQ |
Interrupted quick |
Iso |
Isophase |
IUQ |
Interrupted ultra quick |
IVQ |
Interrupted very quick |
K |
|
km |
Kilometre(s) |
kn |
Knot(s) |
L |
|
LANBY |
Large Automatic Navigational Buoy |
LASH |
Lighter Aboard Ship |
Lat |
Latitude |
Ldg |
Leading |
LFl |
Long-flashing |
Lndg |
Landing for boats |
LNG |
Liquefied Natural Gas |
Long |
Longitude |
LPG |
Liquefied Petroleum Gas |
Lt(s) |
Light(s) |
M |
|
m |
Medium |
m |
Metre(s) |
m |
Minute(s) of time |
M |
Mud |
M |
International nautical mile(s) or sea mile(s) |
min |
Minute(s) of time |
Mk |
Mark |
mm |
Millimetre(s) |
Mo |
Morse code |
Mon |
Monument |
MR |
Marine Reserve |
N |
|
N |
North |
NE |
North-east |
No |
Number |
NT |
Net tonnage |
NW |
North-west |
O |
|
Obscd |
Obscured |
Obstn |
Obstruction |
Oc |
Occulting |
Occas |
Occasional |
ODAS |
Ocean Data Acquisition System |
Or |
Orange |
P |
|
P |
Pebbles |
PA |
Position approximate |
PD |
Position doubtful |
Priv |
Private |
Prod Well |
Submerged production well |
PSSA |
Particularly Sensitive Sea Area |
Pyl |
Pylon |
Q |
|
Q |
Quick |
R |
|
R |
Coast radio stations QTG service |
R |
Red |
R |
Rock, rocky |
Ra |
Radar |
Racon |
Radar transponder beacon |
RC |
Circular marine radiobeacon |
RD |
Directional radiobeacon |
Ref |
Refuge |
Rep |
Reported, but not confirmed |
RG |
Radio direction-finding station |
RoRo |
Roll-on, Roll-off (RoRo Terminal) |
Ru |
Ruin |
RW |
Rotating-pattern radiobeacon |
S |
|
S |
Sand |
s |
Second(s) of time |
S |
South |
SALM |
Single Anchor Leg Mooring |
SBM |
Single Buoy Mooring |
SD |
Sounding doubtful |
SE |
South-east |
Sec |
Second(s) of time |
sf |
Stiff |
Sh |
Shells |
Si |
Silt |
Sig |
Signal |
SMt |
Seamount |
so |
Soft |
Sp (Church) |
Spire |
SPM |
Single Point Mooring |
SS |
Signal station |
St |
Stones |
SW |
South-west |
sy |
Sticky |
T |
|
t |
Tonne(s), Ton(s), Tonnage (weight) |
temp |
Temporary |
Tr |
Tower |
U |
|
ULCC |
Ultra Large Crude Carrier |
UQ |
Ultra quick |
UTC |
Universal Time Coordinated |
UTM |
Universal Transverse Mercator |
V |
|
v |
Volcanic |
vert |
Vertically disposed |
Vi |
Violet |
VLCC |
Very Large Crude Carrier |
VQ |
Very quick |
VTS |
Vessel Traffic Service |
W |
|
W |
West |
W |
White |
Wd |
Weed |
Well |
Wellhead |
WGS |
World Geodetic System |
Whis |
Whistle |
Wk(s) |
Wreck(s) |
Y |
|
Y |
Amber |
Y |
Orange |
Y |
Yellow |
Formats of hydrographic data
Below is a brief description of the most widely used sonar data formats used for storage and reporting.
Формат XTF
The format eXtended Triton Format (XTF) developed by the firm Triton Imaging, Inc. for recording of various types of hydrographic survey data, including data of SSS, seismoacoustics and multipath echo sounder data, with reference to coordinates and depth information. XTF is the most commonly used format for the above data types in the hydrographic survey industry. Version 1.0 of the XTF format was introduced by Triton in 1988. The latest version 18.0 extends the XTF format to support the latest generations of SSS and synthetic aperture sonar, increased dynamic range and image quality. Triton's philosophy of promoting open data formats and continuous improvement has established the XTF format as the de facto standard among sonar manufacturers.
Parametric profilers (PPF)
The parametric Profiler (PPF) is a sonar system using nonlinear acoustics techniques for underwater search of silted objects and stratification of bottom sediments. The employ of parametric radiating antennas in the mode of emission of complex signals in hydroacoustic equipment allows to obtain a high distance resolution with a significant increase in the depth of penetration of the signal into the thickness of the sea bottom soil.
Perspective of development of modern sonar technology is based mainly on the increase of informativity of hydroacoustic channel through the use of new types of signals, improving the radiation methods and treatment, greater use of the potential in amplitude, frequency and phase characteristics of complex wideband signals.
To solve a number of specific problems of hydroacoustics, it is advisable to use parametric radiating antennas, the principle of operation of which is based on the nonlinear interaction of acoustic waves during propagation. The usage of parametric antennas in hydroacoustic equipment allows to increase the information content and accuracy in the detection and determination of the coordinates of underwater objects, to obtain additional features for recognition, due to their broadband, high directivity, low level of lateral field and significantly increase the signal / noise ratio in a complex interference environment.
The range of specific tasks that can be solved with the help of parametric sonar systems is very broad. These include the problems of stratification of marine sedimentary structures with a comprehensive assessment of soil properties, search for objects and pipelines in the bottom silt, environmental monitoring of water areas, quantitative assessment and determination of species composition of fish clusters, detection of swimmers, measurement of the response force of marine objects in a wide frequency range, remote measurement of the vertical distribution of sound velocity in the sea, etc.
The main elements of the parametric antenna are: a section of the aqueous medium in which the nonlinear interaction of pump waves occurs and a pump antenna, which is an antenna array consisting of two sublattices of elements with different resonant frequencies. Sublattices are inserted into each other so that the elements are arranged in the order of alternating types. Figure 1 shows a round-shaped dual-frequency pumping antenna. Around the antenna array is a receiving antenna in the form of a ring.
Aperture of the directional characteristics of the antenna is ~3° and is almost permanent at all difference frequencies in the range of 7-20 kHz. The level of the side field does not
exceed - 40dB.
The high directivity of PPF when emitting low, well-penetrating frequencies into the ground, allows to achieve a good resolution and thereby obtain detailed information about the studied area. Due to its wide bandwidth PPF is able to solve adaptively the problem of bottom sediment profiling, allowing you to choose the optimal operating frequency depending on the variety and type of bottom soil. In this case, the " sounded " volume at different frequencies will be the same due to the property of constancy of the directional characteristics of the parametric antenna in a wide frequency range.
It is possible to increase essentially energy potential of PPF by means of complex, for example, LFM signals only. However the usual practice of increasing the signal energy by significantly increasing the signal duration while reducing the amplitudes of the emitted signals to facilitate the operation of the emitting antenna and power amplifiers for a parametric antenna is not suitable. This is explained by the amplitude dependence of the efficiency of the nonlinear wave interaction process. Since the pressure of the signal of the difference frequency is proportional to the product of the pressure levels of the pump waves, it is not possible to reduce significantly the emitted acoustic power.
PPF with wideband signals allows to increase range resolution through optimal processing.
The results of experimental studies show that the range resolution is 15 cm with a pulse duration of 2 ms. The use of longer pulses will significantly increase the depth of penetration at the same range resolution.
It should be noted that PPF is an almost indispensable tool for searching silted objects, pipelines and other objects located in the thickness of the sea bottom soil due to its broadband and high directivity at low frequencies.
Interferometric side-scan sonar (ISSS)
Interferometric side-scan sonar (ISSS) also refers to sonars that allow swath depth measurements ( swath survey of the bottom). The principle of obtaining depth data in ISSS is different from that used in multibeam sonar (MES). If in a multibeam sonar depth measurements are made by processing the amplitude of the echo signal, in ISSS - by processing the phase of the signal. Figure 1 shows the sketchy principle of depth measurement in ISSS . |
To calculate the depth in ISSS it should be measured angle (direction) to the selected point of the bottom surface and the distance to it, as in multipath sounders. And the calculation of the depth at the selected point is made by an algorithm similar to the algorithm of the multipath sonar. The difference lies in the calculation of the angle (direction) to the selected element of the bottom. The angle (direction) to the selected bottom element on figure 5 is conventionally shown by a dotted line. Figure 5 conventionally shows the bottom as a horizontal line, where the resolution element on the bottom surface is conventionally marked by the number 1 . A1 and A2 are two receiving antennas spaced at the distance ℓ, and ℓ is greater than the wavelength λ of the acoustic oscillation. It should be borne in mind, that since the distance between the antennas A1 and A2 is significantly less than the distance from the antennas to the resolution element, in fact, the lines from the antennas A1 and A2 to the resolution element will be parallel, as shown conditionally in figure 1. The echo signal from the resolution element 1 is received by the antennas A1 and A2. The ISSS uses the fact that the distance from resolution element 1 to antenna A1 and antenna A2 are different to determine the direction to element 1. In ISSS, this distance difference is measured by measuring the phase difference of the two echo signals-this is the segment A2B. The relations in the rectangular triangle A1A2D are used for this purpose. It can be shown that the direction to the resolution element 1 is uniquely related to the distance between the antennas and the calculated beam path difference. If we now add another transmitting antenna to the two antennas, then it will be possible to measure the propagation time of the signal from the emitting antenna to the resolution element and back. Thus, having only three channels, it is possible to measure both the distance to the bottom resolution element and the angle of its observation. We can say that the angle of observation to the bottom resolution element in ISSS is analogous to the beam deflection angle in MES . As a result the system hardware is very simplified only three channels instead of 120, but the number of rays, on the contrary, increases. Thus, for the ISSS Hydra series, operating at a frequency of 240 kHz, the resolution element of the range is 4 cm, which with a viewing range of 200 meters per side gives 20000/4 =5000 rays against 120 in MES . To increase the accuracy of depth measurements, you can average, for example, 10 resolution elements, and thus increase the signal-to-noise ratio by 3 times, which will increase the accuracy of depth measurements. And still in the end you get 500 rays, which is an order of magnitude more than the number of rays in MES . An increase in the signal-to-noise ratio of IS leads to an increase in the accuracy of measurements, the swath of view with respect to MES, and a greater number of rays gives more detailing to the resulting terrain. As a result, the total swath ISSS on both sides is 6 depths. To calculate the true trajectory of the beam in the ISSS, it is necessary to use the data on the sound velocity profile, and for pitching correction – the roll-pitch sensor. It should be noted that with a small pitching ISSS can work without a roll- pitch sensor, determining the angles of inclination of the antenna system by special processing of the received data. But in addition, ISSS is a sonar system that allows simultaneously, with depth measurements, to obtain high-quality acoustic image of the bottom, and fully combined at that with bathymetric data. Comparing with MES, it should be noted that, firstly, not all MES allow to obtain a high-quality acoustic image of the bottom, and secondly, in MES, obtaining an acoustic image of the bottom is a function of the echo sounder and can not always function simultaneously with the depth measurement. ISSS has no such drawbacks . |
|
IP protection standard
The designation of the degree of protection against external factors is indicated by two codes-X1 and X2.
The X1 and X2 codes form the standard encoding of the IP security standard. Example: IP67 (X1 = 6, X2 = 7-full protection against dust, protection against temporary immersion in water to a depth from 15 cm to 1 m under standard pressure conditions)
Code |
X1 (protection against penetration of foreign objects) |
X2 (protection against water) |
0 |
No |
No |
1 |
Protection against foreign objects with a diameter of 50 mm or more |
Protection against vertical water drops |
2 |
Protection against foreign objects with a diameter of 12.5mm or more |
Protection against water jets directed at an angle of 150 |
3 |
Protection against foreign objects with a diameter of 2.5 mm or more |
Protection against water jets directed at an angle of 600 |
4 |
Protection against foreign objects with a diameter of 1 mm or more |
Protection against water jets from all directions |
5 |
Protection against dust |
Protection against jet streams of water from all directions |
6 |
Full protection from dust |
Protection against jet streams of water from all directions without restrictions (example: ship deck) |
7 |
|
Protection against temporary immersion in water to a depth from 15 cm to 1 m under standard pressure conditions |
8 |
|
Protection against prolonged immersion in water |
Hydroacoustics - a tool for studying water areas
The centuries-old history of human society, its entire path to progress is closely connected with the ocean — with navigation, with the development of its huge food, raw materials, and later, fuel and energy resources. ‘ Very soon, the Ocean may be associated with the problem of the very existence of mankind,’ — said the famous researcher of the depths of the sea Jacques-Yves Cousteau. ‘Very soon all of us will have to bow to the God of the seas-to ask him to share his wealth with people’, ‘The threat of mineral famine will literally force a person to actively explore the Ocean’, - echoed by scientists academics - geologist V. I. Smirnov and oceanologist L. M. Brekhovskikh. What do we know about the Ocean? The relief of the land has long been reflected in detailed geographical maps, and the relief of the bottom of the vast expanse of the Ocean until recently was only a very rough idea. In 1975, the geological and geophysical Atlas of the Indian ocean was published in the Soviet Union. It has many new detailed maps of the bottom. Oceanologists studied not only the relief, but also the distribution of sediments, the deep structure of the earth's crust, underwater earthquakes, magnetic anomalies. Nowadays, the Ocean is studied in different ways. It is difficult to explore the depths by special devices without reliable communication with the surface. And the radio waves that serve us faithfully on Earth and in space, go out in the water, having overcome only tens or hundreds meters. Replace them until now can only waves of acoustic.
Hydroacoustics
Hydroacoustics deals with the generation, transmission, reception and use of natural sound. Since radio and light waves are largely absorbed by ocean waters, and sound waves are hardly absorbed, sound is used to probe the ocean floor, locate various objects in the oceans, study the nature of sediments, and as a means of communication. The earliest use of underwater sound was the installation of bells submerged under floating beacons and buoys. During periods of poor visibility, the sound of these bells could be detected at great distances by hydrophones mounted in the ship hull. In 1912, Thomas Green Fessenden developed an electromagnetic sound source that allowed communication between ships by underwater signaling using Morse code. The development of the echo sounder was another example of the early use of hydroacoustics. In 1937, for the first time a new method of depth measurement was applied, based on the effect of reflection of the sound signal from the bottom. Depth echo-sounding measurements have changed the previous ideas of scientists about the topography of the ocean floor. Almost all soundings are now carried out by echo-sounders, and the method itself is called the echo-sounding. The speed of propagation of audio signals is usually 1460 m / s (800 fathoms). For accurate depth measurement it is absolutely necessary to have an oscillation source with a strictly defined periodicity of sending sound signals. Otherwise, minor deviations in the periodicity of the signal sending and changes in the supply voltage may affect the synchronicity of the recorder, which will entail significant errors in determining the time between the direct and reflected sound pulse on the echogram. Most echo-sounders currently in use are equipped with built-in stabilizers of the period of the signal sending, which ensures a stable control voltage of the recorders; as a result, an acceptable measurement accuracy is achieved. The echo sounding method does not allow to obtain values of absolute depths with the same accuracy, since the speed of sound passing through the water column is different for different depths. However, repeated probing when the frequency of the signals changes should show the same values. Errors of a different kind while echo-sounding (in older models of echo-sounders ) occur due to the fact that the beam sent by the echo-sounder does not propagate in the form of a narrow vertical beam, but in the form of a cone with a solid angle of about 30°. As a result, in cases where steep slopes are probed, the signal is usually reflected from the point closest to the vessel on the slope, rather than from the bottom surface directly below the vessel. The echo-sounder measures the depth of water under the hull by timing the echo of short sound pulses bouncing off the ocean floor. Initially, the main tasks of sonar were the detection of submarines, determining the range of sound propagation, etc.. Currently, hydroacoustics is a field of applied and scientific research. Sound refraction and reflection are used by geophysicists and marine geologists to study the deep structure of the ocean floor (seismic profiling) and to map the ocean floor (echo-souder measurements). Marine biologists study the sounds made by various forms of marine fauna. The speed of sound propagation is equal to the square root of the ratio of the compressibility of sea water to its density and in the oceans depends on temperature, salinity and pressure (depth). The main influence on the speed of sound renders the temperature. The speed of sound in seawater varies from 1450 to 1570 m / c; it increases with temperature by a variable value of about 4.5 m/c per 1°C; it also increases by 1.3 m/c as the salinity of the water increases by 1 0/00 , and finally it increases with depth by 1.70 m/c for every 100 m. The use of electronic methods for acoustic and seismic studies, as well as for the study of magnetism, gravity heat flow on the oceanic crust is of great importance for the rapid development of marine geology. The development of echo-sounding has prompted specialists engaged in marine underwater surveys to make very detailed maps of continental shelves and slopes. In the 50s, a significant contribution to the development of marine geology was the development and use of seismic profiling by the method of reflected waves, which allowed us to study the nature of structures and formations lying under the surface of the ocean floor. Many continental slopes on the globe have been explored by this method; countless profiles have crossed all the oceans, providing a huge flow of information. Acoustic instruments towed near the seabed provide more accurate terrain profiles than those obtained with instruments mounted on surface vessels. The side scanning method, using onboard or submersible towed instruments (geosonars), makes it possible to cover wide swaths of the bottom on both sides of the moving vessel, so that a three-dimensional picture of the bottom relief can be obtained. Innovations such as satellite navigation and triangulation using a system of submersible buoys equipped with acoustic instruments (transponders) have made significant progress in improving the accuracy of ship positioning. Other electronic navigation devices, as well as ship computers, data storage and processing systems are also used with great success.
Depth measurement methods
Until 1920 all measurements of depths were carried out thus: the sinker suspended on the end of a tench lowered in water; when the sinker reached a bottom (this point was marked on a tench), a tench with sinker pulled out and measured length of a tench. After 1870, the rope tench, whose stretching affected the measurement results, was replaced by a metal cable. To obtain the true depth of the bottom it is necessary that the position of the cable at the time of measurement was close to the vertical. Measuring with a metal cable is also very difficult, even when using high-speed winches and highly maneuverable vessels, from which the descent of the sinker can be carried out at an almost vertical position of the cable. Deep-sea measurement in this way takes hours. There is another method for obtaining a picture of the bottom surface on either side of the ship's route, consisting in the use of sonar, similar to the devices used to detect submarines. The beam of this emitter is directed downward at a slight angle from the surface of the ocean. Seismic profiling by wave reflection method (WRM) is similar to sonar, but uses low-frequency elastic wave pulses instead of high-frequency ones, which are less absorbed when passing through sediments and bedrock layers of the seabed. The boundaries between the layers of sedimentary rocks are obtained in the form of streaks lying under the bottom surface and expressed by the compaction of the recording. This makes it possible to identify the structure of sedimentary layers, determine the depth of the foundation and other important boundaries of the oceanic crust. Also, with the help of seismic studies, it was found, that there is the surface of separation under the oceans, as well as under the continents, below which sound waves propagate at a speed slightly exceeding 8 km/sec, while above this surface their velocity is lower. Academician L. Brekhovskikh developed a detailed theory of sound energy propagation, which he called " underwater sound channel”, and in 1976 he was awarded the State prize together with the team of authors of the monograph “Ocean Acoustics”. The experiments were carried out on the research vessels “Sergey Vavilov " and " Peter Lebedev”, the first floating laboratories specially adapted for this purpose. A similar discovery was also made by the Americans. However, their work was carried out in the strictest secrecy, and the results were not published, probably because of the military orientation of the research. The range of the underwater channels is amazing! The sound of an underwater explosion of one and half kilogram charge in the Atlantic was recorded by instruments in Bermuda, located 4500 km from the site of the experiment. In the air, such an explosion would be heard at a distance of no more than 4 km, and in the forest-no more than 200 m. With the help of waveguides, nuclear tests are currently being recorded. This phenomenon has led experts to a fundamentally new idea of acoustic rescue service: it is enough to blow up a signal grenade to instantly determine the location of an accident or disaster and organize assistance. In addition, the acoustic waveguide got to be very useful for meteorologists: it turns out, underwater receivers can pick up a noise from the epicenter of a hurricane raging hundreds of kilometers from the station. Following the direction and volume of these sounds, it is easy to calculate, in principle, the course of the hurricane, to intercept the echoes of the terrible tsunami, which is especially important for residents of coastal areas — because from Chile to Hawaii tsunami wave passes for 10 hours, and from Chile to Japan - for 20h. A real turtle compared to its sound accompaniment!
Human use of hydroacoustics allows us to explore the Oceans and penetrate its secrets.
Sonars with aperture synthesis
In the development…
Multibeam echo sounder (MES)
The use of a single-beam sonar in the construction of the image of the bottom relief has a significant drawback - a long time required for measurements. Another drawback is the inaccuracy of the bathymetry data between the data obtained from the measurement tacks. The fact that single-beam echo sounder provides accurate depth data only under itself ( along line tack), but between the tacks, in the process of extrapolation, processing is performed according to some models, which may not correspond to actual bottom topography. To eliminate these shortcomings, sonars are currently used, which allow to obtain not only the depth value under them, but also from the side of the line of motion of the vessel, that is, implementing swath survey . Multibeam echo sounder (MES) belongs to to such sonars. The transceiver antenna of MES is a Mills's cross , which allows, in addition to the vertical beam, to form up to 120 inclined beams to the right and left of the vertical beam . The use of Mills's cross compared to a full-scale phased array allows the MES transceiver system to be simplified. However, the use of Mills's cross leads to losses in the signal-to-noise ratio, which leads to a decrease in the range of the sonar ( swath). |
The transmitting antenna is voicing only one area – a narrow strip on the bottom surface directed perpendicular to the line of motion of the MES antenna carrier, while the receiving antenna forms several (up to 120 ones) on each side of the narrow strips directed along the line of motion of the MES antenna carrier. Due to the intersection of the voiced surfaces, summary rays of approximately (1*1) degree wide are formed . This construction of the antenna system leads to the need for multi-channel receiving tract. The number of channels in the receiving tract is equal to the number of rays and reaches 120. Thus, it should be noted a rather complex hardware part of the MES. Depth measurement is performed separately for each beam according to the following algorithm. In the process of shooting, the angle of deviation of each beam from the vertical and the time of propagation of the acoustic signal along each beam to the bottom and back are measured. Next, using simple geometric relations of a rectangular triangle: the depth (vertical cathetus) is calculated for each ray, knowing the length of the hypotenuse and the angle at the apex of the angle. In practice, only half of the 120 beams are actually used in the process of processing, which leads to the fact that the total viewing band obtained during the survey is up to three depths on both sides. The reason for this is the effect of the change in the speed of sound with depth or the profile of the speed of sound, since the change in the speed of sound along the path of propagation of an acoustic oscillation leads to a curvature of its trajectoryThe curvature of the beam path is strongest for far rays. Therefore, when working with MES, special attention should be paid to the quality of data on sound velocity profiles at the measurement site. The antenna system of MES is placed, as a rule, in the bottom of the vessel. This is typical for MES used to measure depths in the seas and oceans. However, recently, the main works began to be carried out on the rivers and the shelf of the seas, in connection with which antenna systems were used, which are attached to the sides of the vessel with the help of rods during measurements. To measure the real angles of deflection of the beams from the vertical in MES, roll and trim sensors are mandatory. Some MES are designed so that the radiation is produced only when the vertical beam of the receiving antenna is strictly vertical, which is determined by the roll-trim sensor. In pitching conditions, this leads to the fact that the sounding, and therefore the acquisition of data on the depths, is made unevenly along the tack line. |
Terms and abbreviations
Below are the main terms, definitions and abbreviations used in the materials of the site.
DB - database
Navy – (military fleet)
HS - hydroacoustic system
SSS - side-scan sonar
SSSE - side-scan sonar with echo sounder
HEC – hydro-engineering constructions
HEPS - Hydroelectric power station
DSSS - dual-frequency side-scan sonar
ISSS - interferometric side-scan sonar
ISSSE - interferometric side-scan sonar with echo sounder
MES - multibeam echo sounder
Mes - Ministry of emergency situations
SW - software
PPF - parametric Profiler
PF - Profiler
ES - echo sounder
DES - dual-frequency echo sounder
Applied technologies