Garmin LORAN TD position format handbook

Loran TD

position
format
handbook

© 1999 GARMIN Corporation

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December 1999 Part Number 190-00190-00 Rev. A

As a convenience to our customers that have used Loran C as

their primary source of navigation, we are now including a

Loran TD Position Format

Loran TD position format in our marine GPS products.

The new Loran TD Position Format will allow our customers to
enter Time Difference (TD) coordinates into their GARMIN GPS.
When a Loran C, TD coordinate is entered in a GARMIN GPS, the
coordinate will go through a conversion that makes it GPS friendly.
The converted coordinate can be used for immediate navigation
and/or stored for future use.

For those unfamiliar with Loran C, but want to use TD coordi­nates in your GARMIN GPS, it will help to have a basic under­standing of Loran C and it’s components. This booklet is designed
to provide you with enough basic knowledge of Loran C to allow
you to setup and use the GARMIN Loran TD Position Format.

SIGNAL

GRI

9610

SEC

TD

14874.6

V

SEC

TD

32128.1

W

1

Loran TD Position Format

9940 (W)

9940 (X)

9940 (X)

9940 (W)

9940

9940 (M)

9610 (W)

9940 (Y)

9940 (Y)

9610 (V)

(M)

9610 (X)

8970 (Y)

8970 (M)

9960 (Z)

8970 (Z)

9610 (Z)

9610 (Y)

Loran C is a radio navigation system, operated and maintained
in the United States by the Untied States Coast Guard. The name
Loran is an acronym for ‘LOng RAnge Navigation’.

The Loran C system covers the entire United States and the U.S.
Coastal Confluence Zone. From a mariner’s perspective, the Loran C
system is used primarily for ocean and coastal navigation. It can be

used as a supplemental system for harbor and harbor

approach navigation, and for inland navigation by

9960 (W)

8970 (X)

9960 (M)

9960 (X)

9960 (Y)

8970 (W )

recreational vehicles. Loran C will be phased out as a
primary source of navigation, but should remain active
until after the turn of the century. It will be replaced by
GPS. The Global Positioning System provides greater

accuracy and world wide coverage.

The Loran C system consists of groups of land based

transmitter stations called chains. A chain contains a Master

station (M) and at least two, but more commonly 4 or 5 Second­ary stations designated (V) Victor, (W) Whiskey, (X) Xray, (Y) Yankee,
and (Z) Zulu. These stations are separated by several hundred miles.

9610 Master Station and 8970 (Z) Zulu
Station share a common transmitter.

2

Many of the Loran C transmitter stations serve multiple roles.
A transmitter can serve as a Master Station for one chain and a
secondary station for multiple chains. An example would be chain
9610’s Master Station and chain 8970’s Zulu Station. These operate
from the same transmitter located in Boise City, OK.