Roger G0HZK's Javascript Programs for Amateur Radio (here with permission)

Original page is here - last edited : 06 Feb 2018 13:01:30:. New version available!
Calculators Version 4.11 edited: 31 Jan 2007 09:33:23

These programs have been tested with Internet Explorer 6.0, Firefox 1.07 and Opera. They are written in Javascript, and should work on most modern browsers released since 2000. If you have any problem, please let me know exactly which browser and OS you are using. The Javascript code is all bog standard so should not have any undesired effects on your computer.

If you can see the interface and enter data, but nothing happens, then it's possible that you have disabled Javascript on your computer. My programs might even tell you this! You can save the programs to your PC easily - just right-click in the window and select "Save Source" in most cases. Save as html code.

If there are any problems or suggestions, please contact: Roger GHZK

Distance Calculator

This is just a simple page to calculate distance and bearing between two IARU locators. Simply type them into the two locator fields, and click on the calculate button.

IARU locators were designed by radio amateurs as a simple, brief way of pinpointing their stations. A six-character locator refers to a unique area of 2.5 degrees of latitude and 5 degrees of longitude. The locator consists of two letters, two numbers, and another two letters, for example JN23RG. Eight and ten character locators may also be used, e.g. JN23RG39 and JN23RG39AW. These seldom used locators represent more precisely defined locations.

The Great Circle results are normally of interest to radio amateurs, the Rhumb Line is of interest to navigators.

Locator Calculator

Fill in any of the fields for NGR, Locator or Latitude-Longitude, and click on the appropriate button. If you enter NGR easting and northing, set the grid also. All the other fields, where appropriate, will be calculated.

NGRs can be for GB, Ireland, or the Channel Islands. They are transformed from the local datum to WGS84 before conversion to geographic and locator display. Similarly if a locator or WGS84 geographics are entered, the entry is transformed to the appropriate local datum before calculation of NGR data.


UTM Calculator

This is a simple tool to calculate between UTM, geographics, and IARU locator.

Fill in the appropriate fields, and click on the adjacent calculate button. Make sure you specify the name of the reference ellipsoid used when entering latitude and longitude or UTM.

All calculations based on a locator will result in answers based on the WGS84 ellipsoid, regardless of any selected ellipsoid. This is because the locator system is based on WGS84.


Calculators Version 4.11 December 3, 2006.