Maidenhead Locator System
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The Maidenhead Locator System or Maidenhead Grid squares is a scheme used by amateur radio operators for identifying positions on the Earth. It was proposed by the British radio amateur Dr. John Morris (G4ANB), and later adopted by a group of VHF managers, meeting in Maidenhead, England in 1980, to supplant the older QRA locator system with one that would be usable outside of Europe.
A Maidenhead locator represents a position on the Earth based on latitude and longitude. The earth's surface is first divided into 324 fields. Each such field covers 10 degrees of latitude by 20 degrees of longitude. The leading two letters of a Maidenhead locator specify the field.
Each field is then subdivided further into 100 squares. This is where the alternative name "grid squares" comes from. Each of these 100 squares represents 1 degree of latitude by 2 degrees of longitude. The square is denoted by the two digits following the field letters in the Maidenhead locator. To give an example, the American Radio Relay League's Maxim Memorial Station is found in square FN31.
For additional precision, each square can be sub-divided further, into subsquares measuring 5 minutes of longitude by 2.5 minutes of latitude. The subsquare is encoded into two (optional) trailing letters. The corresponding Maidenhead subsquare locator is hence composed of two letters, two digits, two letters. Two points within the same Maidenhead subsquare are always less than 24 km apart. So a Maidenhead locator gives a lot of precision from a mere six characters, which are easily communicated.
The Maidenhead locator system has been based on the WGS84 model of the earth's surface since 1999.
Today, Maidenhead locators are used and recognized by radio amateur individuals and organizations around the world. Many utilities exist to convert latitude and longitude to locators, as this is a favorite hack for programmers who are also radio amateurs. Commercially available (civil) Global Positioning System receivers are frequently able to display Maidenhead locators.
External links
- ARRLWeb: Grid Locators and Grid Squares (http://www.arrl.org/locate/gridinfo.html)
- ARRLWeb: Calculate Grid Square (http://www.arrl.org/locate/grid.html)
- From the field hunter's web page: An explanation of the system and how it came into being. (http://www.algonet.se/~jonit/fieldlist/maidenhead.htm)
- Maidenhead Grid Squares (http://www.amsat.org/amsat/articles/houston-net/grids.html)