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RSS feedsPrinted maps have been with us for hundreds of years. In that time, they've hardly changed - they're still cumbersome and easily ripped, slowly developing canyon-like creases through important landmarks, and you often need a vast library of them to complete a journey of any significant length.
Not to mention their entirely passive nature: even the best maps still can't tell you where you are. Surely there's a better way.
Well, there is, and it's all thanks to the US military. With the advent of Global Positioning Systems (GPS), it's now possible to pinpoint your precise location anywhere on the planet.
The more advanced GPS hardware can even be connected to a notebook computer or PDA to form a truly active navigation system.
In this feature, we'll be looking at some of the systems available to help us work out not just where we are, but where we're going.
And while some may ask the system to plot a route to a far-flung destination like John O'Groats merely as an amusing test, we'll be taking things one step further. We'll actually drive there and back, a total distance of 1,400 miles, relying only on our electronic friends to guide us.
The technology
The basic method by which all Global Navigation Satellite Systems operate is broadly similar. A network of satellites in orbit around the Earth transmits information regarding their location and the precise time as provided by an onboard atomic clock.
Back on Earth, these signals are intercepted and decoded. The receiver calculates the time taken for the signal to reach it by comparing the signal's timestamp with the time it arrived at the receiver. This time differential allows the receiver to estimate its distance from the satellite.
Signals from other satellites arrive at the receiver at slightly different times due to their particular distances. So by triangulating the information received from three satellites, the receiver can calculate its location on a 2D plane.
With information from four or more satellites, the receiver can calculate its position in three dimensions, so it can tell you how high up it may be.
The dominant system available today, GPS, is just one of several in existence. The US Department of Defense began developing the system in 1973, and launched 24 satellites between 1989 and 1994 to provide global coverage for military applications.
To prevent adversaries from benefiting from the system, a process known as Selective Availability (SA) deliberately degraded the GPS signals, limiting their accuracy to around 100m.
Luckily for us, a Presidential Directive was issued in 2000 removing Selective Availability, thereby giving all GPS-based equipment a free overnight upgrade and a potential accuracy of 15m.
Perhaps not surprisingly, given the military significance, Russia has its own system, dubbed Global Navigation Satellite System (Glonass), or Global'naya Navigatsionnaya Sputnikovaya Sistema if you'd prefer the Russian original.
Originally using 24 satellites launched between 1982 and 1998, Only eight are currently operational, although the introduction of a more accurate Glonass-M system is due for completion some time next year.
Although 15m accuracy isn't bad when you consider that the satellites are 20,200km above the surface of the Earth, additional systems are being implemented to improve this level of accuracy still further.
Known as Satellite Based Augmentation Systems (SBAS), these rely on a network of ground stations at specific locations to provide correction information for the existing signals.
These systems compensate for atmospheric delays and changes in the satellite's position, and allow GPS equipment to be used in a much wider range of industries and applications where precise positioning data is required.
The US-based Wide Area Augmentation System (WAAS) improves GPS accuracy to within 3m and will eventually be used to provide precision guidance information for aviation applications. Of course, WAAS only works on WAAS-enabled receivers used in the US.
Asia will launch its Multifunctional Transport Satellite-based Augmentation System (MSAS) in 2005, while the European Geostationary Navigation Overlay Service (EGNOS) is due to go live during 2004.
Both provide accuracy down to 5m or less. EGNOS uses three geostationary satellites and a network of 34 ground stations to increase the performance of the GPS and Glonass systems, and is the first step towards Europe's own GNSS system - Galileo.
Galileo is designed to be a highly accurate and reliable global positioning service, and will be retained under civilian control.
The system can interoperate with the existing GPS and Glonass satellites, allowing almost guaranteed system availability and accuracy down to 1m.
However, the full network of 30 satellites and matching ground stations won't be operational until 2008, so there's some work to be done yet.
So, enough of the acronyms. Let's play with the kit.
The choice of devices
Handheld GPS receivers have been around for a while, but have mostly been the preserve of outdoor enthusiasts.
Generally, these devices incorporate a screen, at least some basic map data, and the facility to record and download tracks and waypoints created during a journey.
Using NMEA 0183, an established standard that defines how various electronic devices communicate, it's also possible for Microsoft Autoroute 2004 to interface with these devices, to provide access to greater levels of processing power and map data.
There are plenty of devices to choose from, but for our mammoth road-trip we'll be using Magellan's flagship, the Meridian Color, and Garmin's handy little Etrex Vista.
Both connect to a notebook PC using a serial interface cable, although the Garmin's connection is far less fiddly than the Magellan's system of a connector block with a captive screw that requires at least three hands to attach.
Both units can provide power from their batteries for 12 hours or so, but combined power and data cables ensure a constant supply of juice while plugged into your notebook.
Vehicle mounts are also available - we found Garmin's mounts to be a little on the weak side, but third-party manufacturers have this cornered, particularly with the extensive range of somewhat oversized suction mounts produced by Ram Mounts.
Once connected and set to output NMEA data into Autoroute, both perform similarly, although in our test the Meridian achieved a fix on its current position slightly quicker than the Etrex.
Autoroute's GPS support means it's constantly aware of your current location and, combined with the Find Nearby Places function, it's easy to find cash machines, petrol stations, car parks and hospitals no matter where you are.
The big advantage of using handheld GPS receivers such as the Magellan and the Garmin lies in their ability to work away from the notebook.
If you fancy a day hiking in the wilds, disconnect the GPS and take it with you. On your return, connect the GPS to your notebook, and use the proprietary software (Mapsource for the Garmin, Mapsend for the Magellan) to download a breadcrumb trail of your trip.
Once saved, you can keep it to use again another day, or email it to your hiking buddies to use with their own GPS gear. Here, the Garmin wins, with its clearer screen and smaller, more comfortable dimensions.
Notebook with dedicated GPS receiver
If you're not going to use the GPS receiver away from your notebook, what's the point in paying for that extra functionality? It's a good question, and one well answered by dedicated GPS receivers such as the Royaltek Sapphire.
The Sapphire is a small dome that perches atop the vehicle's dashboard and connects to the notebook via serial or USB port. It takes its power either from a cigarette lighter adaptor or the USB port directly, cutting down on the number of wires trailing across your car's interior.
As far as Autoroute is concerned, it operates in much the same way as the handheld devices, returning a stream of NMEA data to maintain your current position on Autoroute's map.
Planning our road-trip, Autoroute recommended the M40 towards Birmingham, before picking up the M6 to Carlisle and from there, the M74 to the outskirts of Glasgow.
We modified the route a little here, overriding Autoroute's desire to see Edinburgh and the Forth Bridge, and added Stirling as a 'via' point so as to pick up the A9 earlier and avoid getting stuck in traffic.
From there, the route follows the A9 past the Grampians, through Inverness and up the east coast to John O'Groats and journey's end.
The Sapphire did an excellent job of maintaining satellite lock, and was also very quick to re-establish a fix after being disconnected from the notebook for any period of time, thanks to a built-in lithium battery that helps it to remember your last known position for up to four days.
Royaltek can also furnish you with a range of cables to allow the Sapphire to be used with a PDA, should you prefer to leave your notebook behind.
Autoroute 2004 includes Microsoft Pocket Streets for the Pocket PC, which allows a subset of Autoroute's map data to be exported to your PDA.
Pocket Streets replicates Autoroute's GPS tracking functions, so you can use your PDA to precisely locate your position, and to find nearby places of interest.
A GPS-equipped notebook running Autoroute is a great way to find out where you are and what's around you. It's a bulky solution, though, and still doesn't provide route guidance. For that, we need something a little more specialised.
PDA with GPS receiver and software
Tomtom is a complete navigation system based around a Pocket PC. Comprising Tomtom Navigator software, a Tomtom GPS, and even a Tomtom car kit, everything is included to add a fully featured satellite navigation system to your car.
Tomtom's new Wireless GPS, a cute little box with a built-in rechargeable battery (with a five-hour capacity), uses Bluetooth to send data to your Pocket PC.
The wireless system obviously means fewer wires hanging around, but it also has another advantage: some new car windscreens have a heat-reflective coating, or fine heating elements bonded inside the glass, that can interfere with the reception of GPS signals.
With a Bluetooth GPS, the receiver can be placed anywhere in the car - on the rear parcel shelf, for example - where it can pick up a better signal.
Feed in your destination, and the Tomtom software will calculate the most appropriate route. Then choose from either a rolling map or a 3D display that illustrates the road ahead and the path you should take, while at the same time receiving clear voice instructions through the Pocket PC's speaker.
Tomtom also includes extensive points-of-interest information, just like Autoroute, displayed on the map as icons and available as a list of nearby places that can be used as route destinations. Running low on petrol? No problem: just ask Tomtom to direct you to the nearest petrol station.
Our verdict
All the GPS units tested performed flawlessly over our 1,400-mile test journey from a signal point of view.
Handheld devices, such as the Magellan and the Garmin, are great if you lead an active lifestyle and can make the most of their dedicated features.
As an occasional companion to a notebook and Autoroute, it's difficult to recommend them over the Royaltek Sapphire, which represents the best value for money of all the kit here.
The Tomtom did throw up a couple of issues with its route calculation: once at John O'Groats the Tomtom refused to calculate a direct route home, instead preferring to give up after five minutes of calculating and start all over again.
We cured that particular foible by first plotting a route to somewhere a little nearer, and from there the Tomtom was happy to take us home.
It also failed to recalculate the route when we were forced to take a diversion due to closures on the M6, continually insisting that we 'perform a U-turn if possible'. It wasn't.
However, the routes it came up with were generally good, voice instructions were clear and delivered in good time, and as a complete system it's hard to beat. At last, we have a real alternative to printed maps.
See also:
All Peripheral Devices
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