eLORAN

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LORAN Operational Status

The evolution of the LORAN system from the LORAN-C spec to eLoran is well on its way with the majority of the hardware in place.  The enhancements which are required to transtion from LORAN-C to eLoran are broken into three phases:

Transmitter Modernization

Transmitter modernization includes installation of a modern solid state 100 kHz radio transmitter and uninterruptible Power Supplies (UPS).  This modernization removes all of the vaccum tube transmitters from the system and uses a transmitter which is effectively more modern than many of the GPS satellites.

• 100% of the transmitters in the lower 48 states have been modernized.
• 20 of the 24 LORAN transmitters in the United States have been modernized.

Operational Changes

The operational change to the LORAN system for eLoran changes the system from "System Area Monitor" to "Time of Transmission" (TOT).  This change will allow ranging to be performed off each transmitter instead of the Time Difference chain navigation used by the LORAN-C system.  This change requires each transmitter to be synchronized to Universal Time Coordinated (UTC) and local clocks to be installed at the transmitters.

• 20 of the 24 LORAN transmitters in the United States have the hardward required for TOT transmission.
• 5 Transmitters are currently transmitting TOT on one rate.

9th Pulse

The 9th Pulse or data pulse is being added to the LORAN-C eight pulse specification for eLoran.  The 9th pulse is encoded with UTC and local area corrections to improve the accuracy of the system.

• The 9th pulse data channel has been successfully tested on several U.S. transmitters.
• The data channel has been shown to improve position accuracy to ~10m in harbor entrance and approach situations and provide UTC time of day information.