Magellan GPS315

Satellite navigation experts Magellan have created the GPS 315, an advanced version of its GPS 300. At its most basic, the GPS 315 will tell you where you are at any particular point - very handy if you 'misplace yourself' in featureless terrain in the mist. However, the neat little unit carries a host of other features which make it an ideal tool for walkers, mountain bikers and other outdoor sports enthusiasts.

There are nine navigation screens which you can flit between at the touch of a button and we found it to be very easy to use after we'd spent a wee bit of time brushing up on the instructions.

The first screen, the status screen, tells you how many satellites you are using and also lets you know how much battery life you've got left. The unit runs on two AA batteries and you're best to use extra-life batteries as the unit uses quite a lot of power in the course of a day out, particularly when you're new to it and flicking through the screens is still a novelty. Up to 15 hours of continuous operation should be possible and we certainly got a full day on the hills out of a pair of batteries.

The position screen gives you the coordinates or grid reference of the point you are at and also tells you your elevation and has a compass and trip computer to let you know how far you've come. There's even a speed reading which tells you how fast you're walking!

The satellite constellation that provides the GPS information used by the receiver is maintained by the US Department of Defense (DoD). GPS for general used provides 25m accuracy or better. However, since the signals generated by these satellites are accessible by the public, using a unit like this, the DoD has introduced errors in the satellite signals for security reasons (not very sporting of them!).

At present your GPS position will be accurate within 100 metres horizontally and 150m vertically. Magellan say it is possible to get readings outside of these values at times. In tests I found the grid reference given at any particular point to be very close when I compared it to grid references on my OS Landranger at known locations. This was very comforting and would make the unit a very useful tool in the event of the user finding him or herself lost in mist where it could prove to be a a life saver. The elevation did vary quite a bit - anything from 50 metres to 100 metres - but remained within the variations Magellan mention.

The unit needs a relatively unobstructed view of the sky to pick up satellites quickly and has the power to track 12 of them using its quadrifilar antenna. When you first use the unit you have to initialise it but this takes just a few seconds and can be done from the comfort of your arm chair. You then have to select between marine or land depending on your primary use of the unit. Walkers will obviously set for land. Once out, the satellite pick up was very quick - between just a few seconds and a minute to acquire the information it needed to plot a position.

The compass screen displays sun and moon icons which allow you to align it and use it as a compass. It will also show you your programmed destination allowing you to follow a bearing to this, which is a very useful feature.

The plot screen provides a mini map which charts where you have been and where you want to go if you have programmed in points along your route. You can programme in waypoints and also create a multi-leg route, linking up various waypoints on a planned route. The unit will store up to 20 routes, each with up to 30 legs and you can set alarms which tell you when you are nearing, have reached a waypoint, or have overshot. You can store up to 500 waypoints in the unit's memory and a 'Goto' key allows you to create a direct route to any stored point.

The unit allows you to use a variety of co-ordinate systems, including OS grid references, and the precreens with the instruction book which is clear and easy to follow. It takes a wee while to work your way through the various features but if you've grasped Windows 95, then it should be no problem as you go through all the steps using 'windows' whic-programming is easy once you get the hang of the unit. When you first open the box, it is best to take the unit outdoors and work your way through the sh are quick and easy to flip between and if you make a mistake it is easy enough to go back and rectify it.

If you're planning to travel abroad you can also select grids for Ireland, Switzerland, Finland, Sweden, Germany and France. The unit uses magnetic north as a default reference but you can easily switch between this and true north.

The GPS 315 features a built-in database of more than 15,000 cities and towns of various sizes around the world which is handy for relating a position to the nearest sizeable centre of population. You can also download locations, landmarks and routes from a PC and a CD-Rom is available containing thousands of points of interest around the world.

The GPS 315 weights in at seven ounces including batteries and includes a back up lithium battery which means you don't lose all your programmed information between normal battery changes. The unit, which is waterproof and seems to be tough enough to withstand knocks, fits neatly into the palm of a hand (it measures 15.75cm x 5.08cm x 3.30cm) and includes a wrist strap. It also has a backlit display with two levels of brightness but use this selectively as it puts a strain on the batteries.

The Magellan GPS315 costs £170 including VAT. For further information about the Magellan range, contact Next Destination Ltd, 25 The Clarendon Centre, Salisbury Business Park, Salisbury, Wiltshire, SP1 2TJ. Tel 01722 410800.