Editing Navigation (section)

===Electronic navigation===
[[File:Navigation_system_on_a_merchant_ship_2.jpg|thumb|right|Radar ranges and bearings can be used to determine a position.]]
====Radar navigation====
{{Further|Radar navigation|Doppler radar#navigation}}

Radars can be used for navigation and [[Marine radar|marine radars]] are commonly fitted to ships for navigation at sea.<ref name="e303">{{cite book | title=Safe Nav Watch | publisher=[[Witherby Publishing Group]] | publication-place=Livingston, Scotland | date=2023 | isbn=978-1-914993-46-6 | page=37}}</ref> Radar is an effective aid to navigation because it provides ranges and bearings to objects within range of the radar scanner.<ref name="Anwar133">{{cite book | last = Anwar | first = Nadeem | title = Navigation Advanced for Mates and Masters | edition = 2nd | date = 2015 | publisher = [[Witherby Publishing Group]] | location = Edinburgh | pages=133–139 |isbn = 978-1-85609-627-0}}</ref> When a vessel (ship or boat) is within radar range of land or fixed objects (such as special radar aids to navigation and navigation marks) the navigator can take distances and angular bearings to charted objects and use these to establish arcs of position and lines of position on a chart.<ref name="chap744">Maloney, 2003:744.</ref> A fix consisting of only radar information is called a radar fix.<ref name="bow816">Bowditch, 2002:816.</ref> Types of radar fixes include "range and bearing to a single object,"<ref name="nima163">National Imagery and Mapping Agency, 2001:163.</ref> "two or more bearings,"<ref name="nima163"/> "tangent bearings,"<ref name="nima163"/> and "two or more ranges."<ref name="nima163"/> Radar can also be used with [[ECDIS]] as a means of position fixing with the radar image or distance/bearing overlaid onto an [[Electronic navigational chart|Electronic nautical chart]].<ref name="Anwar133"/>

Parallel indexing is a technique defined by William Burger in the 1957 book ''The Radar Observer's Handbook''.<ref name="nima169">National Imagery and Mapping Agency, 2001:169.</ref> This technique involves creating a line on the screen that is parallel to the ship's course, but offset to the left or right by some distance.<ref name="nima169"/> This parallel line allows the navigator to maintain a given distance away from [[navigational hazard|hazards]].<ref name="nima169"/> The line on the radar screen is set to a specific distance and angle, then the ship's position relative to the parallel line is observed. This can provide an immediate reference to the navigator as to whether the ship is on or off its intended course for navigation.<ref name="Victor">{{cite book | last = Victor| first = Alain| title = Parallel Index Techniques in Restricted Waters -| edition = 2nd | date = 2020 | publisher = [[Witherby Publishing Group]] | location = Edinburgh |isbn = 9781856099165}}</ref>

Other techniques that are less used in general navigation have been developed for special situations. One, known as the "contour method," involves marking a transparent plastic template on the radar screen and moving it to the chart to fix a position.<ref name="nima164">National Imagery and Mapping Agency, 2001:164.</ref> Another special technique, known as the Franklin Continuous Radar Plot Technique, involves drawing the path a radar object should follow on the radar display if the ship stays on its planned course.<ref name="nima182">National Imagery and Mapping Agency, 2001:182.</ref> During the transit, the navigator can check that the ship is on track by checking that the pip lies on the drawn line.<ref name="nima182"/>

====Radio navigation====
{{main|Radio navigation|Radio direction finder}}
[[File:Accuracy of Navigation Systems.svg|thumb|upright=1.2]]
A radio direction finder or RDF is a device for finding the direction to a [[radio]] source. Due to radio's ability to travel very long distances "over the horizon", it makes a particularly good navigation system for ships and aircraft that might be flying at a distance from land. RDFs works by rotating a directional [[Antenna (electronics)|antenna]] and listening for the direction in which the signal from a known station comes through most strongly. This sort of system was widely used in the 1930s and 1940s. RDF antennas are easy to spot on [[Germany|German]] [[World War II]] aircraft, as loops under the rear section of the fuselage, whereas most [[United States|US]] aircraft enclosed the antenna in a small teardrop-shaped fairing.

In navigational applications, RDF signals are provided in the form of ''radio beacons'', the radio version of a [[lighthouse]]. The signal is typically a simple [[Amplitude modulation|AM]] broadcast of a [[morse code]] series of letters, which the RDF can tune in to see if the beacon is "on the air". Most modern detectors can also tune in any commercial radio stations, which is particularly useful due to their high power and location near major cities.

[[Decca Navigator System|Decca]], [[OMEGA Navigation System|OMEGA]], and [[LORAN-C]] are three similar hyperbolic navigation systems. Decca was a [[hyperbola|hyperbolic]] [[low frequency]] [[radio navigation]] system (also known as [[multilateration]]) that was first deployed during [[World War II]] when the Allied forces needed a system which could be used to achieve accurate landings. As was the case with [[Loran C]], its primary use was for ship navigation in coastal waters. Fishing vessels were major post-war users, but it was also used on aircraft, including a very early (1949) application of moving-map displays. The system was deployed in the North Sea and was used by helicopters operating to [[oil platform]]s.

The OMEGA Navigation System was the first truly global [[radio navigation]] system for aircraft, operated by the [[United States]] in cooperation with six partner nations. OMEGA was developed by the United States Navy for military aviation users. It was approved for development in 1968 and promised a true worldwide oceanic coverage capability with only eight transmitters and the ability to achieve a four-mile (6&nbsp;km) accuracy when fixing a position. Initially, the system was to be used for navigating nuclear bombers across the North Pole to Russia. Later, it was found useful for submarines.<ref>{{Cite web |last=Proc |first=Jerry |title=Omega |url=http://www.jproc.ca/hyperbolic/omega.html |access-date=2024-11-22 |website=www.jproc.ca}}</ref> Due to the success of the [[Global Positioning System]] the use of Omega declined during the 1990s, to a point where the cost of operating Omega could no longer be justified. Omega was terminated on September 30, 1997, and all stations ceased operation.

LORAN is a terrestrial [[radio-navigation|navigation]] system using [[low frequency]] radio transmitters that use the time interval between radio signals received from three or more stations to determine the position of a ship or aircraft. The current version of LORAN in common use is LORAN-C, which operates in the [[low frequency]] portion of the EM spectrum from 90 to 110 [[Hertz|kHz]]. Many nations are users of the system, including the [[United States]], [[Japan]], and several European countries. Russia uses a nearly exact system in the same frequency range, called [[CHAYKA]]. LORAN use is in steep decline, with [[Global Positioning System|GPS]] being the primary replacement. However, there are attempts to enhance and re-popularize LORAN. LORAN signals are less susceptible to interference and can penetrate better into foliage and buildings than GPS signals.

====Satellite navigation====
{{Further|Satellite navigation}}
[[File:Furuno Electric GPS Navigator GP-80 at Greenpeace's Rainbow Warrior II 20110108.jpg|thumb|right|A ship's Furuno GNSS receiver showing a GPS position]]
A GNSS allow small [[electronics|electronic]] receivers to determine their location ([[longitude]], [[latitude]], and [[altitude]]) within a few meters using [[time signal]]s transmitted along a [[Line-of-sight propagation|line of sight]] by [[radio]] from [[satellite]]s.<ref name="SafeNavWatchGNSS"/> Positions derived can then be used with maps and charts for [[satellite navigation]]. Since the first experimental satellite was launched in 1978, GNSS have become an indispensable aid to navigation around the world, and an important tool for [[cartography|map-making]] and [[surveying|land surveying]]. GNSS also provides a precise [[time transfer|time reference]] used in many applications including scientific study of [[earthquake]]s, and [[synchronization]] of telecommunications networks. Global Navigation Satellite System or GNSS is the term for satellite navigation systems that provide positioning with global coverage.<ref name="SafeNavWatchGNSS">{{cite book | title=Safe Nav Watch | publisher=[[Witherby Publishing Group]] | publication-place=Livingston, Scotland | date=2023 | isbn=978-1-914993-46-6 | page=34-36}}</ref>  The first system, GPS was developed by the [[United States Department of Defense]] and officially named NAVSTAR GPS (NAVigation Satellite Timing And Ranging Global Positioning System). The [[satellite constellation]] is managed by the [[United States Air Force]] [[50th Space Wing]]. The cost of maintaining the system is approximately [[United States dollar|US$]]750 million per year,<ref name="GPS overview from JPO">[http://gps.losangeles.af.mil/jpo/gpsoverview.htm GPS Overview from the NAVSTAR Joint Program Office] {{webarchive|url=https://web.archive.org/web/20060928042828/http://gps.losangeles.af.mil/jpo/gpsoverview.htm |date=2006-09-28 }}. Accessed December 15, 2006.</ref> including the replacement of aging satellites, and research and development. Despite this fact, GPS is free for civilian use as a [[Public good (economics)|public good]].

With improvements in technology and developments globally, as of 2024, there are several different operational GNSS now available for navigation by the public. These include the [[United States]] NAVSTAR [[Global Positioning System]] (GPS), the [[Russia]]n [[GLONASS]], the [[European Union]]'s [[Galileo positioning system]] and the [[Beidou navigation system]] of [[China]].<ref name="SafeNavWatchGNSS"/> The different global systems have varying differences in accuracy but stated positions are normally in the range of between 1 and 10 metres accuracy depending on system and on that system's satellite coverage.<ref name="SafeNavWatchGNSS"/> As a result over 100 satellites are in [[medium Earth orbit]], transmitting signals allowing GNSS receivers to determine the receiver's [[geographic location|location]], speed and direction.<ref name="SafeNavWatchGNSS"/> There are also several regional GNSS systems available for navigation, including the [[Indian Regional Navigation Satellite System]] and the [[Quasi-Zenith Satellite System]]. However, not all GNSS receivers are capable of operating with these systems and older GNSS receivers, such as on old ships may not be capable of receiving all of the GNSS now available to users.<ref name="SafeNavWatchGNSS"/>

Modern [[smartphones]] act as personal [[GNSS]] navigators for civilians who own them. Overuse of these devices, whether in the vehicle or on foot, can lead to a relative inability to learn about navigated environments, resulting in sub-optimal navigation abilities when and if these devices become unavailable.<ref>{{Cite journal|last=Gardony|first=Aaron L|date=April 2013|title=How Navigational Aids Impair Spatial Memory: Evidence for Divided Attention|journal=Spatial Cognition & Computation|volume=13|issue=4|pages=319–350|doi=10.1080/13875868.2013.792821|bibcode=2013SpCC...13..319G |s2cid=7905481}}</ref><ref>{{Cite journal|last=Gardony|first=Aaron L.|date=June 2015|title=Navigational Aids and Spatial Memory Impairment: The Role of Divided Attention|journal=Spatial Cognition & Computation|volume=15|issue=4|pages=246–284|doi=10.1080/13875868.2015.1059432|bibcode=2015SpCC...15..246G |s2cid=42070277}}</ref><ref>{{Cite book|title=Spatial Information Theory|last=Winter|first=Stephen|publisher=Springer Berlin|year=2007|isbn=978-3540747888|location=Heidelberg, Germany|pages=238–254}}</ref> Typically a [[compass]] is also provided to determine direction when not moving.

==== Acoustic navigation ====
{{main|Sonar|Acoustic location}}

[[Acoustic location]] is a method of navigation by the use of acoustic positioning systems which determine the position of an object by using [[sound waves]]. It is primarily used by [[submarines]] and ships fitted with [[sonar]] and similar transducer based technologies.<ref name="l124">{{cite book | last1=Christ | first1=Robert D. | last2=Wernli | first2=Robert L. | title=The ROV Manual | chapter=Practical Applications | publisher=Elsevier | year=2014 | isbn=978-0-08-098288-5 | doi=10.1016/b978-0-08-098288-5.00021-x | pages=561–599}}</ref><ref name="k448">{{cite web | title=Long Range Acoustic Communications and Navigation in the Arctic | url=https://acomms.whoi.edu/wp-content/uploads/sites/20/2016/11/FreitagBallPartanKoskiSingh_Arctic_2015.pdf | publisher=Woods Hole Oceanographic Institution |access-date=2025-02-24}}</ref> [[Underwater acoustic positioning system]]s are also commonly used by divers and [[Remotely operated underwater vehicle]]s, specifically the [[Long baseline acoustic positioning system]], the [[Short baseline acoustic positioning system]] and the [[Ultra-short baseline acoustic positioning system]].<ref name="l124"/><ref name="c798">{{cite web | title=Precision acoustic navigation for remotely operated vehicles (ROV) | url=https://bibliotekanauki.pl/articles/985799.pdf | publisher=Hydroacoustics, 2005 - bibliotekanauki.pl| access-date=2025-02-24}}</ref>