Navigation is a field of study that focuses on the process of monitoring and controlling the movement of aircraft or vehicles from one place to another. The navigation field includes four general categories: land navigation, marine navigation, aeronautical navigation, and space navigation.
It is also an art term used for the specialized knowledge used by the navigator to perform navigational tasks. All navigation techniques involve placement of the navigator position compared to a known location or pattern.
Navigation, in a broader sense, can refer to any skill or study involving positioning and direction. In this sense, navigation includes orienteering and pedestrian navigation.
Video Navigation
Histori
In the medieval period of Europe, navigation was considered part of the set of seven mechanical artifacts, none of which were used for the long journey across the open ocean. Polynesian navigation may be the earliest form of open ocean navigation, based on memories and observations recorded on scientific instruments such as Marshall Stick Charts. Early Pacific Polynesian uses stellar motion, weather, position of certain wildlife species, or wave size to find paths from one island to another.
Marine navigation using scientific instruments such as the first breeder astrolabers took place in the Mediterranean during the Middle Ages. Although ground astrolabes were found in the Hellenistic period and existed in ancient classical and the Golden Age of Islam, the earliest record of marine astrolabes was the Majorcan astronomer Ramon Llull dating from 1295. The refinement of this navigational instrument was associated with the Portuguese navigator during the early Portuguese discovery in the Age of Discovery. The earliest known explanations of how to construct and use marine astrolabes came from the Spanish cosmographer MartÃÆ'n CortÃÆ'Â © de Albacar Arte de Navegar ( The Art of Navigation ) published in 1551, based on the principle archipendulum used in building Egyptian pyramids.
The Open-seas navigation using astrolabes and compasses began during Age of Discovery in the 15th century. The Portuguese began to systematically explore the African Atlantic coast from 1418, under the sponsorship of Prince Henry. In 1488 Bartolomeu Dias reached the Indian Ocean with this route. In 1492 the Spanish kings funded Christopher Columbus's expedition to sail west to reach the Indies by crossing the Atlantic, resulting in the Discovery of America. In 1498, the Portuguese expedition ordered by Vasco da Gama reached India by sailing around Africa, opening direct trade with Asia. Soon, the Portuguese sailed further east, to the Spice Islands in 1512, landing in China one year later.
The first round trip of the earth was completed in 1522 with a Magellan-Elcano expedition, a Spanish exploration voyage led by Portuguese explorer Ferdinand Magellan and completed by Spanish navigator Juan Sebastià ± n Elcano after the creator's death in the Philippines in 1521. The fleet of seven ships sailed from Sanlººcar de Barrameda in southern Spain in 1519, crossed the Atlantic Ocean and after several stopovers rounded the southern tip of South America. Several ships were missing, but the remaining fleets continued across the Pacific making a number of discoveries including Guam and the Philippines. At that time, only two galleons left from the original seven. The Victoria led by Elcano sailed across the Indian Ocean and north along the coast of Africa, to finally arrive in Spain in 1522, three years after his departure. The Trinidad sailed east from the Philippines, trying to find a maritime path back to America, but to no avail. The eastern route across the Pacific, also known as tornaviaje (return journey) was only discovered forty years later, when the Spanish cosmographer AndrÃÆ' © s de Urdaneta sailed from the Philippines, northward to parallel 39  °, and press Kuroshio Current to the east which takes its galleon across the Pacific. He arrived in Acapulco on October 8, 1565.
Maps Navigation
Etymology
The term comes from the 1530s, from the Latin navigationem (like navigatio ), from navigatus , pp. From navigare "sail, sail, go by sea, steer the ship," from navis "vessel" and root agere
Basic concept
Latitude
Roughly, the latitude of places on Earth is the distance of the north or south corner of the equator. Latitude is usually expressed in degrees (indicated by  °) ranging from 0  ° at the Equator to 90  ° at the North and South poles. The Arctic Latitude is 90  ° N, and the Arctic latitude is 90  ° Mariners calculates the latitude in the northern hemisphere by looking at the northern star of Polaris with a sextant and using a visual vision table to correct the height of the eye. and atmospheric refraction. The height of Polaris in degrees above the horizon is the observer's latitude, in one or two degrees.
Longitude
Similar to latitude, the longitude of places on Earth is the distance of the east or west corner of the main meridian or meridian of Greenwich. The longitude is usually expressed in degrees (indicated by  °) starting at 0 ° in the Greenwich meridian up to 180 ° east and west. Sydney, for example, has a longitude of about 151  ° east. New York City has a longitude of 74 ° west. For much of history, seafarers struggle to determine longitude. Longitude can be calculated if the exact time of sight is known. Lack of that, one can use a sextet to take the distance of the moon (also called the observation of the moon, or the lunar for that short), with a nautical almanac, can be used to calculate the time at zero longitude (see Greenwich Mean Time ). A reliable marine chronometer was not available until the late 18th century and was not reached until the 19th century. For about a hundred years, from about 1767 until about 1850, unmarried marines used the distance method of the moon to determine the time of Greenwich to find their longitude. A sailor with a chronometer can check his reading using the Greenwich timing of the month.
Loxodrome
In navigation, the rhumb line (or loxodrome) is the line that intersects all the longitude squares at the same angle, ie the path originating from the specified initial bearing. That is, after taking the initial pads, one continues with the same bearing, without altering the measured direction relative to the true north or magnetic.
Modern techniques
Most modern navigation relies primarily on positions electronically determined by recipients collecting information from satellites. Most other modern techniques depend on the line of crossing positions or LOP. Position lines can refer to two different things, lines on graphs or lines between observers and objects in real life. Bearing is a measure of direction to an object. If the navigator is measuring the direction in real life, then the angle can be drawn on the ocean chart and the navigator will be at that line on the graph.
In addition to the pads, the navigator also often measures the distance to the object. In the chart, the distance produces a circle or a position arc. Circles, bows, and position hyperboles are often referred to as position lines.
If the navigator pulls two line positions, and they intersect he should be in that position. Improvement is the intersection of two or more LOPs.
If only one row of positions is available, this can be evaluated against the Dead Date position to set an approximate position.
Position lines (or circles) can be derived from various sources:
- celestial observation (short segment of the same height circle, but generally represented as a line),
- terrestrial ranges (natural or man-made) when two mapped points are observed parallel to each other,
- compass to the mapped object, Radar
- range to the mapped object,
- on a particular coastline, the depth heard from the echo loudspeaker or the line of the hand.
There are some rarely used methods today like "dipping the light" to calculate the geographic range of the observer to the beacon
The navigation method has changed through history. Each new method has increased the seafar's ability to complete its voyage. One of the most important assessments that the navigator must make is the best method to use. Some types of navigation are described in the table.
Navigational practice usually involves a combination of these different methods.
With a mental navigation examination, a pilot or navigator estimates the track, distance, and altitude which will then help the pilot avoid dirty navigation errors.
Trial
Piloting (also called a pilotage) involves navigating an aircraft with a visual reference to a landmark, or a vessel in a limited waterway and fixing its position as quickly as possible at frequent intervals. More than any other navigation phase, proper preparation and attention to detail is important. Procedures vary from ship to ship, and between military, commercial, and private vessels.
The military navigation team almost always consists of several people. A military navigator may bring the person stationed in the gyro repeater on the bridge wing to take simultaneous bearings, while the civilian navigator must often pick and plan on his own. While the military navigator will have a pads book and someone to record entries for every improvement, the civil navigator will only steer the pads on the charts as they are taken and not record them at all.
If the ship is equipped with ECDIS, it makes sense for the navigator to monitor the progress of the vessel along the selected path, ensuring visually that the ship is going as it wishes, checking the compass, voice and other indicators only occasionally. If a pilot is on board, as is often the case in the most limited waters, his judgment is generally reliable, further reducing the workload. But if ECDIS fails, the navigator must rely on his skills in manual procedures and time-tested.
The heavenly navigation system is based on observing the positions of the Sun, Moon, Planet and the stars of navigation. Such systems are also used for terrestrial navigation such as for interstellar navigation. By knowing which point on earth rotates the celestial body above and measuring its height above the observer's horizon, the navigator can determine its distance from the subpoint. A sea almanac and a marine chronometer are used to calculate the point on earth of an extraterrestrial body, and the sextes are used to measure the height of the body angle above the horizon. The altitude can then be used to calculate the distance from the subpoint to create a circular position line. A navigator shoots a number of stars in succession to provide a series of overlapping position lines. Where they intersect is the improvement of the sky. Moon and sun can also be used. The sun can also be used by itself to fire a series of position lines (best done around midday) to determine position.
Marine Kronometer
To measure longitude accurately, the exact time of the sighting of a sextant (up to seconds, if possible) should be recorded. Every second error is equivalent to 15 seconds longitude error, which at the equator is a 0.25 nautical mile position error, about the accuracy limit of manual navigation ceiling.
Spring-driven marine chronometer is a precision watch used on board to provide an accurate time for celestial observation. The kronometer differs from a spring-driven clock especially in that it contains a variable lever device to maintain pressure even at the primary impulse, and a special balance designed to compensate for temperature variations.
The spring-driven chronometer is set to approximately the average Greenwich (GMT) time and is not reset until the instrument is overhauled and cleaned, usually within three years. The difference between GMT and chronometer time is carefully determined and applied as a correction for all chronometer readings. A wind-driven chronometer should be fed at the same time each day.
Quartz crystal marine chronometers have replaced spring-driven chronometers in many ships because of their greater accuracy. They are maintained at GMT directly from the radio timing signal. This eliminates the chronometer error and watch error correction. If both hands are wrong by the readable amount, it can be electrically reset.
The basic element for time generation is the quartz crystal oscillator. Quartz crystals are compensated with temperature and sealed in an evacuated envelope. Calibrated setting capabilities are provided to adjust crystal aging.
The Kronometer is designed to operate for at least 1 year on a set of batteries. The observations can be timed and the ship's clock is set with a comparative watch, which is set to the time of the chronometer and taken to the wing of the bridge to record the time of sight. In practice, coordinated watches to the closest seconds to the chronometer will be sufficient.
A stop watch, either a spring or digital wound, can also be used for celestial observation. In this case, the watch starts at a GMT known as a chronometer, and the elapsed time of each vision is added to this to obtain GMT from the vision.
All chronometers and watches should be checked regularly with radio timing signals. Time and frequency of radio timing signals are listed in publications such as Radio Navigational Aids.
The ocean sextant
The second important component of celestial navigation is measuring the angle formed in the observer's eye between a celestial body and a reasonable horizon. The sextant, an optical instrument, is used to perform this function. The sextant consists of two main assemblies. The frame is a rigid triangular structure with a pivot at the top and a circle passing segment, called the "bow", at the bottom. The second component is the index arm, which is attached to the pivot at the top of the frame. At the bottom is an endless vernier that clamps into the teeth at the bottom of the "bow". The optical system consists of two mirrors and, generally, a low power telescope. One mirror, called the "index mirror" is set to the top of the index arm, above the pivot. When the index arm is moved, the mirror rotates, and the scale that passes on the arc shows the measured angle ("altitude").
The second mirror, referred to as the "horizon glass", is mounted on the front of the frame. Half of the silver-colored skyline and the other half are clear. The light from the celestial body attacks the index mirror and is reflected to the silver portion of the horizon glass, then returns to the observer's eye through the telescope. The observer manipulates the index arm so that the reflection image of the body on the horizon only rests on the visual horizon, visible through the clear side of the horizon glass.
The sextant adjustment consists of checking and aligning all optical elements to eliminate "index correction". The index correction should be checked, using the horizon or more preferably the star, whenever the sextes are used. The practice of observing the celestial observations of the rolling deck of a ship, often through cloud cover and with a blurred horizon, is by far the most challenging part of celestial navigation.
The inertial navigation system is a type of dead tally navigation system that calculates its position based on motion sensors. After initial latitude and longitude are established, the system receives an impulse from a motion detector that measures the acceleration along three or more axes allowing it to continuously and accurately calculate the current latitude and longitude. The advantage over other navigation systems is that, once the starting position is set, it requires no outside information, it is unaffected by bad weather conditions and can not be detected or stuck. The disadvantage is that the current position is calculated only from the previous position, the error is cumulative, increasing at a level that is roughly proportional to the time since the initial position is entered. Inertial navigation systems should often be corrected by 'refinement' the location of some other type of navigation system. The US Navy developed the Inertial Naval Navigation System (SINS) during the Polaris missile program to ensure safe, reliable, and accurate navigation systems for missile submarines. Inertial navigation systems are widely used until satellite navigation systems (GPS) become available. The Inertial Navigation System is still commonly used on submarines, since GPS reception or other repair sources are not possible when submerged.
A radio or RDF direction finder is a device for finding directions to a radio source. Because of the radio's ability to travel very long distances "above the horizon", it makes an excellent navigation system for ships and aircraft that may fly at a distance from land.
RDF works by turning the directional antenna and listening to the direction in which the signal from the known station comes very strong. This kind of system was widely used in the 1930s and 1940s. The RDF antenna is easily recognizable on German World War II planes, as a loop beneath the rear of the fuselage, while most US planes close the antenna in a fairing in the form of small teardrops.
In the navigation application, the RDF signal is provided in the form of radio beam , the radio version of a beacon. This signal is usually a simple AM ​​broadcast of a series of morse code letters, which RDF can tune to see if the flare is "in the air". Most modern detectors can also listen to commercial radio stations, which is very useful because of its strength and its high location near major cities.
Decca, OMEGA, and LORAN-C are three similar hyperbola navigation systems. Decca is a hyperbolic low frequency radio navigation system (also known as multilateration) that was first used during World War II when Allied forces required systems that could be used to achieve an accurate landing. As well as Loran C, its main use is to navigate ships in coastal waters. Fishing vessels were the main postwar users, but they were also used on planes, including very early mobile map applications (1949). This system is deployed in the North Sea and is used by helicopters operating on oil platforms.
OMEGA Navigation System is the first truly global radio navigation system for aircraft, operated by the United States in cooperation with six partner countries. OMEGA was developed by the United States Navy for military aviation users. It was approved for development in 1968 and promised the capability of ocean coverage worldwide with only eight transmitters and the ability to achieve accuracy of four miles (6 km) while improving position. Initially, the system will be used to navigate nuclear bombers across the Arctic to Russia. Then, found useful for submarines. [1] Due to the success of the Global Positioning System, the use of Omega decreased during the 1990s, to the point where Omega's operating costs could no longer be justified. Omega was discontinued on September 30, 1997 and all stations ceased operations.
LORAN is a terrestrial navigation system using a low frequency radio transmitter that uses time intervals between radio signals received from three or more stations to determine the position of the ship or aircraft. The current LORAN version commonly used is LORAN-C, which operates in the low-frequency part of the EM spectrum from 90 to 110 kHz. Many countries are system users, including the United States, Japan, and some European countries. Russia uses a system that is almost exactly the same in the same frequency range, called CHAYKA. The use of LORAN declines sharply, with GPS being the main substitute. However, there are efforts to improve and popularize LORAN. LORAN signals are less susceptible to interference and can penetrate better to foliage and buildings than GPS signals.
When a ship is within range of a ground radar or a special radar aid for navigation, the navigator can take a distance and angle bearing to map objects and use this to set the position and position lines on the graph. Improvements made up of only radar information are called radar improvements.
The types of radar improvements include "range and bearing for one object," "two or more pads," "tangent bear," and "two or more ranges."
Parallel indexing is a technique defined by William Burger in the 1957 book The Radar Observer's Handbook . This technique involves making lines on the screen that are parallel to the direction of the ship, but balanced to the left or right with a certain distance. This parallel line allows the navigator to maintain a given distance away from danger.
Several techniques have been developed for special situations. One, known as the "contour method," involves marking a transparent plastic template on a radar screen and moving it to a graph to improve position.
Another special technique, known as the Franklin Continuous Radar Plot Technique, involves depicting the path that radar objects must follow on the radar screen if the ship remains on the planned track. During transit, the navigator can check whether the ship is on track by checking that pip is in the line drawn.
In the modern era, smartphones act as personal GPS navigators for all civilians.
The Global Navigation Satellite System or GNSS is a term for satellite navigation systems that provide positions with global coverage. A GNSS allows a small electronic receiver to determine their location (longitude, latitude, and altitude) into a few meters using a time signal transmitted along the line of sight by a radio from a satellite. Recipients on fixed ground ground can also be used to calculate the exact time as a reference for scientific experiments.
As of October 2011, only NAVSTAR Global Positioning System (GPS) United States and GLONASS Russia are fully GNSS operational globally. The EU Galileo positioning system is the next generation GNSS in the initial deployment phase, scheduled to be operational by 2013. China indicates it will expand its regional Beidou navigation system into a global system.
More than two dozen GPS satellites are in medium Earth orbit, signal transmission allows the GPS receiver to determine the location, speed and direction of the receiver.
Since the first experimental satellite was launched in 1978, GPS has become an indispensable aid to navigation around the world, and an essential tool for mapmaking and ground surveying. GPS also provides timely references that are used in many applications including scientific study of earthquakes, and synchronization of telecommunication networks.
Developed by the US Department of Defense, GPS is officially named NAVSTAR GPS (NAVigation Satellite Timing And Ranging Global Positioning System). The satellite constellation is managed by the 50th Air Force Space Wing of the United States. System maintenance costs are approximately US $ 750 million per year, including replacement of old satellite, and research and development. Apart from this fact, GPS is free for civil use as a public good.
Ships and similar vessels
Day Work in navigation is a set of minimal tasks consistent with wise navigation. This definition will vary on military and civilian ships, and from ship to ship, but takes shape that resembles:
- Keep the plot dead continuously.
- Take two or more stellar observations at dusk in the morning to repair the sky (wise to observe 6 stars).
- Observation of the morning sun. Can be taken at or near the vertical prime for longitude, or at any time for the position line.
- Determine the compass error with an azimuth observation on the sun.
- Calculations interval through noon, local daylight watch time, and constants for meridian or ex-meridian sights.
- Day Meridian or sun observation below the longitude for the afternoon latitude. Run a fix or cross with a Venus line for afternoon refinement.
- Day time determination runs and day and drift sets.
- At least one afternoon sun line, if the star is not visible at dusk.
- Determine the compass error with an azimuth observation on the sun.
- Take two or more observations of the stars at dusk in the afternoon to repair the sky (wise to observe 6 stars).
Planning section
Travel planning or shipping planning is a procedure for developing a full description of the cruise ship from start to finish. The plan includes leaving the docks and harbor areas, traveling part of the journey, approaching destination, and mooring. Under international law, the ship's captain is legally responsible for travel planning, but on larger vessels, the assignment will be delegated to the ship's navigator.
Studies show that human error is a factor in 80 percent of navigation accidents and in many cases people who make mistakes have access to information that can prevent accidents. The practice of shipping planning has evolved from the grinding line on the ocean chart into a risk management process.
Part planning consists of four stages: assessment, planning, execution, and monitoring, defined in International Maritime Organization Resolution A.893 (21), Guidelines for Travel Planning, and these guidelines are reflected in the law local IMO signatory countries (eg, Title 33 of the US Federal Code Regulation), and a number of professional books or publications. There are about fifty elements of a comprehensive part plan depending on the size and type of vessel.
The assessment stage relates to gathering information relevant to the proposed voyage as well as ensuring risk and assessing the key features of the voyage. This will involve considering the type of navigation required eg Ice navigation, the ship's territory will pass through and the hydrographic information on the route. In the next stage, written plans are made. The third stage is the implementation of the final shipping plan, taking into account the specific circumstances that may arise such as weather changes, which may require a plan for review or amendment. The final stage of part planning consists of monitoring the progress of the ship in relation to the plan and responding to irregularities and unforeseen circumstances.
Navigation for cars and other land travels typically use maps, landmarks, and recent computer navigation ("satnav", short for satellite navigation), as well as any means available on the water.
Computerized navigation generally relies on GPS for current location information, road map navigation databases and navigable routes, and uses algorithms related to the shortest path problem to identify optimal routes.
Integrated bridge system
The concept of integrated electronic bridge encourages the planning of the future navigation system. The integrated system takes input from a variety of ship sensors, electronic positioning screen information, and provides the control signals necessary to maintain the vessel on a pre-defined course. The navigator becomes the system manager, chooses system presets, interprets system output, and monitors the ship's response.
See also
- Bowditch's American Practical Navigator
- Polynesian Navigation
- Position settings
- Robot navigation
- TVMDC
- Find a Way
- Navigation space
Note
References
External links
- General Concept of Ocean Navigation
- Lecture on Navigation by Ernest Gallaudet Draper
- How to navigate with less than a compass or GPS
Source of the article : Wikipedia
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