The Grid Locator System

 

The Grid Locator System, also known as the Maidenhead Locator System, is a geographic coordinate system used primarily by amateur radio operators to identify locations on the Earth's surface. It provides a concise way to determine a location using a combination of letters and numbers.  The system is named after the town of Maidenhead in England, where it was first developed by John Morris (G4ANB) and Paul Hatcher (G4RRA) in 1980. The Maidenhead locator system divides the surface of the Earth into a grid, making it easy to transmit. Precise location by radio waves without longitude and latitude. The grid is based on a series of letters and numbers, usually represented as a six-digit string (e.g. "FN31pr" or "EM73vx"). Grid positioning is hierarchical and increases precision as you move from left to right in the string.

Here is a breakdown of the  Maidenhead positioning system structure:

The first pair of characters represents a large area called a "field" (eg "FN" or "EM"). There are 18 fields that cover the entire surface of the Earth.

 The second pair of characters specifies the location as a "square", which is an area of approximately 20 x 10 degrees (eg "FN31" or "EM73").  

The third pair of characters narrow the location down to a "SubSquare", which is roughly a  2x1 degree area (e.g. "FN31pr" or "EM73vx"). 

You can increase the accuracy by adding extra marks that divide the SubSquare into smaller areas. 

 Amateur radio operators widely use the Maidenhead Locator system during competitions, field operations, and emergency communications. It is a convenient way to quickly exchange local information via radio communication in a compact form.