Garmin GPS 72 - Manual (Page 59)

Loran TD System
LORAN C is a radio navigation aid operated and maintained in the United States by the
United States Coast Guard. The name LORAN is an acronym for “LOng RAnge Navigation”.
The LORAN system covers the entire United States and the U.S. Coastal Confl uence Zone.
From the perspective of a mariner, the system is used for ocean and coastal navigation. It
can be used as a supplemental system for harbor and harbor approach navigation, and it is
used for inland navigation by recreational vehicles.
LORAN TD Feature
The LORAN TD (Time Delay) feature eases the transition from using LORAN to using
GPS. The GPSMAP unit automatically converts GPS coordinates to LORAN TDs for those
who have a collection of LORAN fi xes for favorite fi shing spots and other waypoints
recorded as TDs. You can display your position as a TD or enter waypoints as TDs. The
accuracy to be expected from this conversion is approximately thirty meters. When the
unit is placed in the LORAN TD format mode, it simulates the operation of a LORAN
receiver. Position coordinates may be displayed as TDs, and all navigation functions may be
used as if the unit was actually receiving LORAN signals.
Using the LORAN TD Format
When creating new waypoints using LORAN TD coordinates, you must set the correct
LORAN chain number and secondary stations in the Setup TD fi eld before storing the
waypoint. After the waypoint is stored in unit memory, it will always reference the LORAN
chain number and secondary stations currently selected in the Setup TD fi eld. If you enter
a different LORAN chain number, change the secondary stations or offsets in the Setup TD
fi eld, the active waypoint information will refl ect those changes. Since the GPS 72 does
not rely on the LORAN signal for navigation, it can reference a different GRI chain and/or
secondary stations and still navigate to the location stored in memory.
57
Introduction
57
Appendix G
Loran TD
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