Editing Satellite navigation (section)

===LEO satellites===
The two current operational [[low Earth orbit]] (LEO) [[satellite phone]] networks are able to track transceiver units with accuracy of a few kilometres using doppler shift calculations from the satellite. The coordinates are sent back to the transceiver unit where they can be read using [[AT command]]s or a [[graphical user interface]].<ref>{{cite web |url=http://common.globalstar.com/doc/common/en/products/gsp1700_usermanual.pdf |title=Globalstar GSP-1700 manual |access-date=2011-12-30 |archive-date=2011-07-11 |archive-url=https://web.archive.org/web/20110711101531/http://common.globalstar.com/doc/common/en/products/gsp1700_usermanual.pdf |url-status=dead }}</ref><ref>{{cite web |url=http://www.skyhelp.net/acrobat/jan_05/Iridium%20SBD-FAQ%201-05.pdf |last=Rickerson |first=Don |date=January 2005 |title=Iridium SMS and SBD |publisher=Personal Satellite Network, Inc. |archive-url=https://web.archive.org/web/20051109014357/http://www.skyhelp.net/acrobat/jan_05/Iridium%20SBD-FAQ%201-05.pdf |archive-date=9 November 2005 |url-status=dead}}</ref> This can also be used by the gateway to enforce restrictions on geographically bound calling plans.