Enhanced Loran (eLoran) Navigation
Stalwart Radio System Chosen to Backup Any Potential GPS Failure
Loran-C is slated to be upgraded with modern technology to serve as an effective backup to GPS satellite navigation.
Recently the Department of Homeland Security announced in a press release its intention to adopt an upgrade of the currently installed Loran-C radio navigation system in an effort to complement use of existing Global Positioning System (GPS) technology. The new enhanced or eLoran system will insure the livelihood of a historically functional and highly reliable radio navigation system.
Overview - Over the years, the low-frequency LOng RAnge Navigation (LORAN) system has provided a reliable navigation standard for aviators and mariners. Existing Loran technology provides positioning accuracy of 460 meters or 1,500 feet. With the advent of GPS satellite technology, many thought that this legacy system had become irrelevant.
Researchers have looked at an update to Loran that would take advantage of new technology and provide a system that could effectively backup use of GPS equipment if it should fail. Called eLoran, it would ensure safe navigation for vessels even if satellite signals are disrupted or cannot be received.
Advantages - eLoran utilizes high power transmitters broadcasting low frequency emissions that are difficult to jam and are resistant to interference. Small, inexpensive eLoran receivers can easily be built into global navigation equipment to ensure redundancy in position and time data. eLoran can act as a static compass, a feat GPS is incapable of duplicating.
Navigation information provided by eLoran will be accurate enough to support non-precision aircraft instrument approaches, coastal harbor approaches by vessels in low-visibility conditions, and land navigation. The system will provide exceedingly accurate time and frequency references needed by the telecommunications industry.
eLORAN Signal - The legacy Loran system currently in use is called Loran-C. eLoran improves upon it with the addition of a separate data channel that can convey signal integrity information, corrections or system warnings. eLoran transmissions will provide a source for accurate Coordinated Universal Time (UTC) that is critical for safe navigation independent of GPS satellites.
System receivers will operate in an "all-in-view" manner were they track all of the eLoran transmitter stations they can receive and use this information to improve position accuracy. This is similar to the way a GPS receiver utilizes all the satellites that it can see or receive signals from above the horizon. The Coast Guard and Federal Aviation Administration are currently testing on-air tests of the Loran Data Channel (LDC).
eLoran holds the promise of an reliable and user friendly adjunct to current GPS technology. There are several generations of mariners out there that never used any other navigation system until the advent of inexpensive GPS receivers.
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