The GPS (Global Positioning System) question type enables you to automatically log geographical locations within your survey. You will need an appropriate GPS device attached to your Handheld or PC to use this question type.
Latitude, longitude, altitude, and UK National Grid (Eastings and Northings) co-ordinates can be logged as separate fields or can be combined into the same field. If more than one co-ordinate is included in a field then each co-ordinate will be separated by a semi-colon and space, e.g.
55° 58.1593' N; 3° 12.4014' W
Latitude and longitude are expressed in degrees + decimal minutes. Each minute of latitude is approximately 1.8 km therefore the fact that minutes are given to 4 decimal places might suggest an accuracy of 18cm -- this is not so. Actual accuracy will be around 4 to 8 m absolute (although relative accuracy will be better at about 1m). There are many reasons for this, not least the fact that accuracy is deliberately degraded for non-military use. At times of war the US Department of Defense degrades this even further, so don't throw your maps away just yet.
Eastings and Northings
Currently these are only available for locations in the UK and correspond to the grid system commonly used on maps produced by the Ordnance Survey ®.
Eastings and Northings are stated to 10m accuracy in the format <Square code> <Easting> <Northing>, e.g. SK 0915 8540.
Square codes are shown in the diagram below.
GPS on the handheld
Most GPS devices communicate with the handheld through one of the communications ports. Because of the wide variety of GPS devices available and the fact that each handheld may have other accessories that use communication ports, PocketSurvey cannot automatically detect which port your particular GPS device will use. You will need to set the COM port for each individual handheld.
Refer to your particular GPS device manual to determine which communications port is being used, then select Tools | Settings... from the handheld's main menu to produce the dialog shown below.
From here you can change the COM port to that required by the GPS device. (Don't forget the colon after the port number.)
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