Maidenhead Locator System
[1] John Morris G4ANB originally devised the system and it was adopted at a meeting of the IARU VHF Working Group in Maidenhead, England in 1980.
[3] By the time of their April 1980 meeting, in Maidenhead, England, the VHF Working Group had received twenty different proposals to replace the QRA locator grid.
[3] At the 1999 IARU Conference in Lillehammer it was decided that the latitude and longitude to be used as a reference for the determining of locators should be based on the World Geodetic System 1984 (WGS-84).
[2] A Maidenhead locator compresses latitude and longitude into a short string of characters, which is similar in concept to the World Geographic Reference System or GEOREF.
To avoid negative numbers in the input data, the system specifies that latitude is measured from the South Pole to the North Pole, and longitude measured eastward from the antimeridian of Greenwich, giving the prime meridian a false easting of 180° and the equator a false northing of 90°.
Again, to make manual calculations from degrees and minutes easier, 24 was chosen as the base number, giving these subsquares dimensions of 2.5' of latitude by 5' of longitude.
To give an example, W1AW, the American Radio Relay League's Hiram Percy Maxim Memorial Station in Newington, Connecticut, is found in grid locator FN31pr.
Under IARU Region 1 rules, VHF distance calculations are carried out between Maidenhead subsquare centres, assuming a spherical Earth.
[7] In 1985, the Radio Society of Great Britain published a small set of BASIC language routines to convert from locator references to geographical coordinates (latitude and longitude) for further processing.
[9] Many other utilities exist to convert latitude and longitude to locators, as this is a favourite hack for programmers who are also radio amateurs.
Perl supports conversion between geographical coordinates and Maidenhead locators in module Ham::Locator by Andy Smith, available on CPAN.
