User manual GARMIN LORAN TD POSITION HANDBOOK

[. . . ] GARMIN Corporation reserves the right to change or improve its products and to make changes in the content without obligation to notify any person or organization of such changes. Visit the GARMIN website (www. garmin. com) for current updates and supplemental information concerning the use and operation of this and other GARMIN products. GARMIN is registered trademark of GARMIN Corporation and may not be used without the express permission of GARMIN Corporation. December 1999 Part Number 190-00190-00 Rev. [. . . ] These operate from the same transmitter located in Boise City, OK. 9960 (W ) 9960 (X) 9960 (Y) 2 Each Master Station transmits a pulsed radio frequency (RF) signal at a set time interval. This time interval is referred to as the Group Repetition Interval or GRI. The GRI is used to identify the different Loran C transmitter chains. It is not important to understand how this number is determined, just that it represents the Master Station and chain. After a Master Station transmits it's pulsed RF signal, each Secondary station after recieving the master station signal, transmits a pulsed RF signal at a set time delay. As the signals are processed by the Loran C receiver, the master signal is separated and used to measure the difference in time with each secondary signal. The time interval is very short, measured in millionths of a second or micro seconds. This time difference is how the Loran C determines a location. To determine a location, a Loran C must receive signals from a Master and two Secondary Stations of the same chain. From those three signals, a set of two TD's are constructed and using the TD's a location can be plotted. Loran TD Position Format Loran C Chart 3 Loran TD Position Format Position Format Field Loran C users can now use their TD's in GARMIN GPS systems. The new Loran TD position format provides users with the ability to create waypoints using TD's. When a waypoint is created using the Loran TD position format, a background conversion is performed on the TD's. This conversion allows the GPS to navigate to the TD's location. Don't worry, this conversion process will maintain the integrity of the TD location and has proven to be accurate to within 30 meters most of the time. The new waypoint can be used for immediate navigation and/or stored for future use. Let's take a look at how to select and setup the Loran TD Position Format. The Position Format field is located in the Navigation Setup menu. Refer to your GPS Owner's Manual for directions on locating the Navigation Setup Menu. Selecting the Loran TD Position Format: 1. Highlight the Position Format field and press ENTER. Using the Arrows or Rocker Keypad highlight Loran TD and press ENTER. Rocker Keypad After the Loran TD format is selected, a new field will appear to the right of the Position Format. This field, called Setup TD provides access to the Loran Setup page. The Loran Setup page contains fields where the GRI-Chain Number and Secondary Stations are set. [. . . ] The side-bar will help to explain how that affects the waypoints. Navigating While the Loran TD Position Format is selected the unit will display the Loran Chain Number and Secondary Stations selected in the Setup TD page and the TD's for the current location. It is important to remember that the unit is not using the Loran C signal for navigation, but can display TD's as a current location. The GPS uses the same process that it used to create a waypoint, in reverse. The GPS takes that GPS friendly position format and converts it to a TD for display. 6 Remember, it is a good practice to update any waypoint created using TD's while you are actually at the waypoint location. [. . . ]