If contemplating use of a global positioning system (GPS) receiver in\u00a0Britain\u00a0it is\u00a0essential that the OS format is catered for if you wish to relate it to any paper based map.<\/p>\n
In the case of the Garmin 38, 45, 12, 12XL, eTrex, Oregon\/Dakota families (and probably all other walking devices) you should set ‘British Grid’ for format on the navigation setup page.\u00a0 Datum should be set to ‘Ord Srvy GB’ to avoid errors of up to hundreds of metres.\u00a0\u00a0 I choose to set my GPS for metric measurements rather than statute for walking since the maps have a 1Km grid, but tend to use statute for motoring to match the odometer in the car and the road signs, both of which use miles here in the UK!\u00a0\u00a0 ‘Auto magnetic’ for north gives good results and complements my trusty Silva compass, and that was how I set my GPS when I first used it.\u00a0\u00a0 More recently though I have found it much more convenient to set the GPS to ‘Grid’ and I then have consistency between GPS, map and the protractor scale on the compass using the method above.<\/p>\n
The OS reference is given by a Garmin with a resolution of one metre (but not to that accuracy!) – eg.<\/p>\n
SJ\u00a0 12345<\/tt>
\nBNG 67890<\/tt><\/p><\/blockquote>\nThis example shows we are in the 100Km square SJ some 12345 metres east of the square origin and 67890 metres north.\u00a0 The BNG refers (presumably) to British National Grid.\u00a0\u00a0 When inputting the grid reference of a waypoint, note that the receiver requires the two letters and five digits of eastings on one line, and five digits of northings on a separate line.<\/p>\n
Magellan Blazer 12<\/span><\/h3>\n