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Paper maps have traditionally been the primary navigation tool for centuries. maps are most
reliable when used in conjunction with a compass to determine direction and orientation. With GPS technology you might think
maps have become obsolete, it's just the opposite, they have become more important. GPS units and maps should be used together.
Even though you are using a GPS you should never go without the relevant map of the area
you will be in and a compass.
WHAT IS GPS Global Positioning System. A network of satellites that continuosly transmit coded information, which
makes it possible to precisely identify locations on Earth by measuring distance from the satellites.
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The satellites are in what's called a high orbit about 12,000 miles above the earths surface.
A total of 24 satellites (21 are active plus three spares)
Operating from such a high altitude allows the signal to cover larger areas. The satellites
are arranged in their orbits so a GPS receiver on earth can always receive from at least four at any one time
GPS PLUS POINTS
- GPS provides a quick and accurate position fix.
- GPS provides additional useful information such as walking speed, the track you are heading
on,altitude, and sunset and sunrise timings.
- Enables you to walk off, your bearing, but will guide you to your destination.
- Are very useful when used in conjunction with a map.
BE AWARE
- GPS units should never be used as your sole means of navigation
- GPS systems are mini computers and can stop functioning for a variety of reasons.
- Remember GPS's have problems picking up signals in thick woodland, around cliffs or in deep
valleys.
- You should always have enough spare batteries with you.
Knowing how to use a hand - held GPS is very much like trying to use any other piece of electronic
equipment. It has lots of functions and you may only require a few, but later you might find the others useful.
PURCHASING A
GPS There are lots of different hand - held GPS's, all with a wide range of features, ideally it depends
on the individual but things should be considered are:
- Size of screen display
- Some models have colour display, others black or grey tones.
- Battery life (this can vary between models)
- Battery type.
- Integeral maps
- Controls, side or front layout.
- WASS
- Computer interface.
USING A GPS
When you first turn on a GPS, it may take some time to locate the satellites. The best thing to do is to be outside
in a large open area with no obstructions giving you a clear view of the sky.
If you are indoors or bad reception area the GPS will ask some questions, which you will
have to answer, once you have done this it should automatically revert back to the locating mode.
In the advanced view, the GPS will display the location of the satellites and the signal
strength.
POINTER PAGE
The basic pointer page will show the directions to the next waypoint along with the straight line distance
COORDINATE
SYSTEM GPS's can display your location in several formats. A GPS will use WGS84 as the global standard
reference. When using Ordnance Survey maps it should be set to OSGB36, British Grid.
It is important that the units being shown as the position format, the correct map datum
is set. If British Grid is displayed the datum must be set to OSGB and a degrees/minutes display should have WGS84. A mistake
in doing this would put your location out by up to a kilometre.
WAYPOINTS
A waypoint can be marked to recored your location at the time, or entered as a destination. Waypoints will remain
in the memory until deleted, even removing or battery failure will not erase them. You can bring up waypoints from the menu
and edit, change the name or location.
BEARING
When using a compass we would use the direction of travel arrow to walk on a bearing using a GPS has similarities.
Select the desired waypoint, select GOTO and the display will change to the pointer page. On moving, the pointer will show
straight ahead on the display, therfore heading on a direct bearing to the waypoint.
You can also use the map page, where the display will show where you are in relation to the
waypoint. You can also change the display to either map ahead or North.
ROUTES
When using the GOTO option it will only take you to the waypoint you have chosen. If you have entered more than one
waypoint, when you reach it the GPS will automatically change to the next one and will keep doing this until you reach your
final destination.
TRACK LOG
A GPS should have a track log feature, when activated will show your route that you have taken making it possible
to do the journey again. It will also have a track back feature which enables you to retrace your steps back to your starting
point, handy in an emergency
INPUTTING A
ROUTE This can be done by downloading from a PC or by manually inputting the grid references from the OS
map.
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