How to Convert Loran TDs to Latitude & Longitude

Sometimes you will need to enter Loran-C Time Delay readings, or Loran TD's into a GPS receiver that isn't compatible with Loran waypoints. One method is to go to the Loran-C location and re-read the location in Latitude and Longitudinal units. However, this is time consuming. Another way is to use the Loran waypoint as a GPS waypoint, but for technical reasons this is prone to error which can be an issue in fog or when locating an underwater obstruction. However, software is available that can perform the conversion on a PC.

Instructions

    • 1

      Install the software on your PC by browsing to the International Loran Association: Receivers and Coordinate Conversion website, and downloading the University of Wales: Radionavigation Systems Research Group TD2LL software zip file. Extract the zip file by clicking on it and then run the exe file. Ensure the database dat file that's also part of the zip file is located in the same folder as the program.

    • 2

      Launch the program and choose the Loran-C Chain from the drop-down. Choose the conversion method. Enter any TD values in microseconds and enter a position estimate in the "Geographic Coordinates" box if you choose the iterative method of conversion.

    • 3

      Press the "TD2LL" button, and the Loran TDs will be converted.