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[[Image:LAAS Architecture.svg|thumb|300px|LAAS architecture, similar in concept to JPALS LDGPS fixed base category]]
[[Image:LAAS_Architecture.png|right|thumb|LAAS Architecture]]
TheIn the [[United States Armed Forces]], the '''Jointjoint Precisionprecision Approachapproach and Landinglanding Systemsystem''' ('''JPALS)''') is a military,an all-weather system for precision guidance of landing systemaircraft. It is based on real-time differential correction of the [[Global Positioning System|GPS]] (GPS) signal, augmented with a local area correction message, and transmitted to the user via secure means. It is used on terrestrial airfields as well as the [[US Navy]]'s [[amphibious assault ship]]s and [[List of aircraft carriers of the United States Navy|aircraft carriers]] ([[Hull classification symbol|hull classifications]] LH and CVN, respectively).
The onboard receiver compares the current GPS-derived position with the local correction signal, deriving a highly- accurate three-dimensional position capable of being used for all-weather approaches via an [[Instrument Landing System|ILS]]-style display. Accuracy, while classified, is believed to be about 1 m or better. While JPALS is similar to [[Local Area Augmentation System]], but intended primarily for use by the military, some elements of JPALS may eventually see their way into civilian use to help protect high-value civilian operations against unauthorized signal alteration.
==History==
[[Image:JPALS Tactical Prototype.jpg|250px|thumb|JPALS tactical prototype]]
The needdevelopment forof JPALS was identifiedthe inresult response toof two factors.main military requirements. First, the military needs an all-service, highly- mobile all-weather precision approach system, tailorable to a wide range of environments, from shipboard use to rapid installation at austeremakeshift airfields. Second, they need a robust system that maintainscan maintain a high level of reliancereliability in combat operations, particularly, onein that'sits highlyability resistantto toeffectively resist jamming.
==Operation==
JPALS falls intoencompasses two main categories,: SRGPS (shipboard relative [[GPS]]) and LDGPS (land/local differential GPS). SRGPS provides highly- accurate approach positioning for operations aboard ship, including aircraft carriers, helo and SSTO/VTOLVL carriers, and other shipboard operations, primarily, but not limited to, helicopter operations.
LDGPS is further divided into three sub-categories: fixed Fixed Basebase, Tacticaltactical, and Specialspecial Missionsmissions. Fixed Basebase is used for ongoing operations at military airfields around the world, while the Tacticaltactical system is a portable system, designed for relatively short-term, austere airfield operations. The Specialspecial Missionsmissions system is a highly portable system capable of rapid installation and use by [[special forces]].
==Accuracy==
The accuracy of LAAS, or [[Locallocal Areaarea Augmentationaugmentation Systemsystem]], (LAAS) is better than [[Instrument_Landing_SystemInstrument Landing System#ILS_categoriesILS categories|CAT III ILS]] accuracy, and will provide horizontal and vertical resolutions of less than 1 m. Although the exact accuracy of JPALS will remain classified, it's estimated that JPALS will meet or exceed this accuracy for authorized users.
==Benefits==
The main benefit of JPALS is that it's a system that can be taken anywhere, anytime, providing a safe and effective way to conduct 24/7, all-weather, anti-jam instrument landing system capability to all authorized users, worldwide. A secondary benefit is a significant reduction in cost savings over current systems.
The naval version of JPALS transmits a signal that has a low probability of intercept; so it is unlikely that an enemy will detect the signal and trace it back to its source. The existing system, [[tactical air navigation]] (TACAN), is not encrypted or concealed in any way, which can reveal the ___location of the ship on which it is installed. This is not acceptable in [[EMCON|emissions control]] (EMCON) or stealth conditions.
The increase in both accuracy and reliability will significantly enhance operations while reducing non-operational periods due to weather or adversarial efforts, with significant cost savings as a side benefit. ▼
▲The increase in both accuracy and reliability will significantly enhance operations while reducing non-operational periods due to weather or adversarial efforts , with significant cost savings as a side benefit.
==See also==
*[[Local Areaarea Augmentationaugmentation Systemsystem]] is a similar system for civilian usage.
*[[Wide Areaarea Augmentationaugmentation Systemsystem]]
*[[Precision approach]]
*[[Instrument Landinglanding Systemsystem]]
*[[Global Positioning System]]
*[[Differential GPS]]
*[[Microwave landing system]]
*[[Electronics_Technician_(United_States_Navy)|Electronics technician]]
{{GPS}}
* {{note|FAA_FS}}{{cite web ▼
| author=Federal Aviation Administration (FAA) ▼ | yeardate=February 27, 2004 ▼▲* {{note|FAA_FS}}{{cite web
| url=http://gps.faa.gov/Library/laas-f-text.htm ▼▲ | author=Federal Aviation Administration (FAA)
| title=Local Area Augmentation System (LAAS) Fact Sheet ▼▲ | year=February 27, 2004
| accessdate=November 20 , 2005 ▼▲ | url=http://gps.faa.gov/Library/laas-f-text.htm
|archiveurl=https://web.archive.org/web/20060118032723/http://gps.faa.gov/Library/laas-f-text.htm
▲ | title=Local Area Augmentation System (LAAS) Fact Sheet
|archivedate=January 18, 2006
| format=
|url-status=dead
| work=
}}
| publisher=
* {{note|FRP2001}} {{cite web ▼▲ | accessdate=November 20
| accessyear=2005}}
▲* {{note|FRP2001}} {{cite web
| author=Department of Transportation and Department of Defense
| yeardate=March 25, 2002
| url=http://www.navcen.uscg.gov/pubspdf/frp/frp2001/FRP2001.pdf
| title=2001 Federal Radionavigation Plan
| format=PDF
| work=
| publisher=
| accessdate=November 27, 2005
}}
| accessyear=2005}}
* IHS Aerospace - Honeywell (July 7, 2005). [http://aero.ihs.com/news-05Q3/honeywell-laas-update.jsp Honeywell to Update Local Area Augmentation System (LAAS) Prototype.] Press Release.
===External links===
* [http://gpswww.faa.gov/Programsabout/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/index.htm FAA GPS Programs]
* [http://gpswww.faa.gov/Libraryabout/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/laas-f-text.htm/ FAA LAAS Fact Sheet]
* [http://waas.stanford.edu/research/jpals.htm Stanford JPALS Page] {{Webarchive|url=https://web.archive.org/web/20060427122246/http://waas.stanford.edu/research/jpals.htm |date=2006-04-27 }}
* [https://web.archive.org/web/20060311054600/http://www.raytheon.com/products/jpals/ Raytheon JPALS Product Page]
* [http://www.fas.org/man/dod-101/sys/ac/equip/jpals.htm FAS JPALS Page]
* [http://www.globalsecurity.org/military/systems/aircraft/systems/jpals.htm GlobalSecurity.org's JPALS Page]
* [https://web.archive.org/web/20140911053740/http://www.navair.navy.mil/index.cfm?fuseaction=home.displayPlatform&key=8559E3E9-42F1-4A08-876B-5F2E7FA6AAB2 US Navy information]
* [https://web.archive.org/web/20140911052320/http://www.navair.navy.mil/index.cfm?fuseaction=home.PhotoGalleryDetail&key=62593B59-C3A0-454F-8CA4-594D953A0005 US Navy images]
[[Category:{{Satellite navigation systems ]]}}▼
[[Category:Aircraft instrumentslanding systems]]
[[Category:Military aviation]]
[[Category:GPSGlobal Positioning System]]
▲[[Category:Satellite navigation systems]]
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