QTH aka Maidenhead geo locator

QTH over Europe,
by Mysid at Wikimedia Commons

At an unexpected place - the monthly astronomy magazine Sterne und Weltraum - I discovered another system for the alphanumerical encoding of a geographic location. The QTH or Maidenhead locator of the first level consists of two letters and two digits, encoding a rectangle of 1 degree latitude and two degrees of longitude. For higher accuracy a second group of two letters is added, which then encodes a rectangle of 2.5' of latitude by 5' of longitude. At this level, with just six characters a rectangle not wider than 12 kilometer is uniquely encoded.

Bz splitting these into 100 subsquares encoded by their number makes the squares 30" in longitude and 15" in latitude, or less than 500 meter. Rarely used is another group of two characters, which then reaches the accuracy of GPS receivers, and while the algorithm could allow more levels these obviously are nonsensical.

This locator is mostly used by amateur radio stations, not my field of interest, but for whatever reason this locator is also used in the satellite tracking software GPredict which was tested in the magazine. I already found a free implementation of this algorithm and included it into my code, same as I did previously with the Geohash, but it does not yet work fully and I did not yet have the time to debug and fix the probably minor glitch in my modification.

Not really a necessary addition, as the only system of encoding geographical locations used by the Thai authorities is the MGRS variant of UTM, it is still a nice gimmick in my geo class when I make it fully work.