Military grid reference system

The Military Grid Reference System ( MGRS, in the German language also UTM reference system UTMREF ) is a square plan - oriented geographic reporting system and is based on the UTM coordinate system.

The meridian of the UTM coordinate system are divided into grid squares at 100 km side length. These grid squares are numbered with a two letter code, where - as with the UTM system - the letter "I" and "O" remain unused in order to avoid confusion with 1 and 0. This pair of letters to the east and high value of the grid square is the zone number / band Code of UTM system added.

Within this grid squares geographical indications will now be formulated as offsets to the southwestern corner of each grid square, where the resolution - between 10 km and 1 m - is not explicitly specified, but is taken from the number of posts of the attached pair of numbers. Both figures are, by definition, always the same length. Two -digit numbers refers to a 10-km grid square, two five-digit numbers designate a particular square meter surface. In this manner, extremely compact geographical indications can be formulated.

A geographical indication within the UTM reference system is therefore composed of together

  • The UTM zone, numbered from 1 to 60
  • The UTM tape, a letter between C and X
  • The name of each grid square, consisting of the letter pair for the Easting and Northing value.
  • A pair of numbers the same number of digits 1 to 5

Coordinates example

Given the coordinates specified 32UMD7403. It can be written for readability and 32U MD 74 03. This notation is to be read as:

  • UTM zone 32, a 6 degrees of longitude wide strip on either side of the 9 ° longitude East ( central meridian )
  • UTM - band U, an 8 high latitude portion of this zone between 48 and 56 degrees north latitude. Since 8 degrees of latitude a distance of 887.6 km correspond to the UTM bands are only approximately congruent with the nine grid squares in north-south direction.
  • 100 -km grid square MD, north up the central meridian 9 ° From the letter M results in the ' horizontal ' position ( easting ),
  • From the letter D, the ' vertical ' position, the distance to the equator results ( northing ).

Each UTM zone are horizontal 4 per grid squares assigned to either side of the central meridian, thus covering a 800 km wide strip. In the UTM zone 32, these are the letters JKLM and NPQR. First and eighth grid square ( J and R) but verschneiden already at the equator with the external grid squares neighboring zones. There the UTM zones with 668 km its maximum width. To the north of this overlap increases, and as the width of a UTM zone (6 longitudes) 6000 km north of the Equator drops to below 400 km, only 4-6 of these grid squares used in our latitudes generally.

Coding of the grid squares

The two-letter code of a grid square are calculated taking into account the zone number as follows:

The first letter encodes the Easting value, ie, the horizontal position of the grid square. Since each UTM zone in west-east direction is divided into 8 grid squares, and the grid square letters are horizontally formed from an alphabet of 24 characters, the count repeated every three UTM zones.

To determine the position of a grid square relative to the central meridian ( Easting ), divide the zone number divisible by three. With the rest of the division - one, two or zero - you go to the above table and can read the easting value of the letter there.

Calculation example:

  • Grid square 32UMD
  • 32 modulo 3 = 2
  • The letter M marks the grid squares at E400, the sought borders so directly west of the central meridian.

Second letter, vertical coding of the Northing value

The letter code to describe the vertical position of the grid square is formed from an alphabet of 20 characters (AV excluding I and O). He thus repeats every 2000 km (20 grid squares of 100 km altitude).

In odd-numbered zones, the count starts at the equator with 'A', in even-numbered zones with 'F'.

The figure shows the resulting displacement of the grid square numbers can be read between adjacent zones. In zone 33 at N6000 the 20 characters are counted for the third time, so that north on the UV grid square, the grid square UA connects. In even-numbered UTM zones this change by 5 grid squares is offset to the south. Accordingly, the exchange MV - MA already in N5500.

Application Examples

The UTM reference system is used in Germany for orientation by aid agencies and civil protection and by the armed forces and allied forces. The Federal Network Agency writes in the currently valid " TR TKÜV " ( Technical Guidelines for implementation of legal measures for monitoring telecommunications and information requests for traffic data ) provides that for at the location specified in the monitoring of mobile radio terminals " UTM Ref coordinates " as " default value the coordinates "are used.

In Austria, the coordinate system is used only by the army, while the other organizations still use the older BMN system either the UTM system or.

Aid agency Emergency management Bundeswehr
567092
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