Getting lost is one of the most frustrating experiences you can have. This is particularly true if you happen to be driving your car down a motorway or through a big city during a busy time of the day. Finding somewhere safe to stop could in itself be a major headache. And even when you've pulled over and hauled out the map, working out exactly where you are might not be child's play. Maps are all very well, but if you don't know what your current position is, they're not going to be much use.
Luckily, a humble PDA can come to the rescue. By adding a device that receives signals from the GPS (global positioning system) satellite location network and some PDA mapping software, you need never belost again.
In this feature, we'll be surveying what you need to turn your PDA into a navigational aid, explaining how to set it all up, and guiding you through an example road journey. We also explain how to use a GPS off-road for hiking and rambling.
In-car navigation
GPS is still a pretty young technology (see The history and future of satellite navigation). It started to get useful for in-car use when handheld receivers became available that could tell you your position in terms of a standard Ordnance Survey grid reference. However, you still needed a human navigator next to you in order to use it when driving. Real progress occurred when products appeared that could send the co-ordinate information directly to a computer.
Unless you're onboard a ship or have a passenger sitting in the car next to you, however, a notebook isn't really practical - you're unlikely to be able to balance it on your car dashboard. But a PDA is a different story. A built-in car satellite navigation option, if your car model even has one available, will usually set you back more than £1,000, and often twice that. But even if you don't own a PDA yet, the handheld approach is likely to cost less than £500. So it's easy to see why GPS add-ons have been driving PDA sales of late. In fact, analyst IDC has pinpointed the GPS bundle as a major factor shoring up the general decline in PDA sales in Europe compared to the US. Analysts have calculated that 65 per cent of GPS sales are as part of a PDA bundle, and 58 per cent of all PDA peripherals sold are GPS add-ons.
A PDA is the perfect GPS partner, especially now handheld processor speeds are anywhere from 200MHz to 400MHz, with megabytes of memory in tow. The variety of GPS options available is already extensive. Up until recently, you'd need to get a device specifically designed for your PDA model. The first successful designs were aimed at the Compaq iPAQ's innovative jacket connector, such as the original iPAQ Navigation System or Navman's GPS 500. While model-specific units are still widely available, a number of manufacturers have also released Bluetooth-based GPS systems over the past year, and these can work with any Bluetooth-enabled PDA, software permitting.
We've summarised a selection of the most popular PDA GPS add-ons to help you make a buying decision. It's far from a complete list, however, as there are literally hundreds of different models available, especially when you consider all the various bundle deals.
If you already own a PDA, you'll be limited to the GPS add-ons that are compatible with it. Both Pocket PCs and Palm OS PDAs are well catered for, but not every model is compatible, so always make sure yours is before getting out the credit card. As maps can require 20-40MB of space just for a small region like the South East of England, your PDA needs to be able to support removable memory.
However, it's worth noting that while the software features vary a little from vendor to vendor, the underlying maps are basically the same throughout. The GPS map business is dominated by two vendors - Tele Atlas and Navtech. Every unit we've seen uses maps from one of these two companies, so the only variation will be how up-to-date the map set you're supplied with is. For example, Navman and TomTom use Tele Atlas while Socket uses Navtech. If the routing software fails to notice a one-way system or tries to send you on an illegal right turn, it's more than likely a problem with the underlying map, not the software accessing it, and any other product using the same maps will exhibit the same fault.
Wired versus wireless
Although the iPAQ jacket was the first really popular PDA GPS add-on, it's still going strong. Navman's latest SE jacket, as supplied with the GPS 3300 Terrain and GPS 3450, has updated internals but is still compatible with most iPAQs that support jacket add-ons and run Pocket PC 2002 or above.
Kirrio's Navigation Pack for Palm OS, on the other hand, comes with cables so it can be attached to a variety of PalmOne and Sony PDAs, although the Tungsten E edition, unsurprisingly, only includes a cable for the Tungsten E. Similarly, TomTom's Navigator for Palm is only compatible with the Tungsten T3. To use the CoPilot Live Pocket PC 4 CF GPS Quickstart, your Pocket PC will need to have both a CompactFlash and an SD slot, although both software and maps come preloaded on a supplied SD card.
Bluetooth has removed most of the necessity for proprietary cabling for GPS add-ons, although of course your PDA needs to have Bluetooth installed. The same device can support a variety of PDA brands, and even both Palm OS and Pocket PC. Navman's 4410 and 4460 use the same hardware, as does TomTom's. Unfortunately, this doesn't mean one package fits all - you'll still need to make sure you buy the right version for your PDA operating system, as only software for Pocket PC or Palm OS will be supplied. But at least the Pocket PC version will be compatible with any Bluetooth Pocket PC - you won't have to worry about getting the right connectors. You may find that setting up the Bluetooth bonding and communications port settings could be a headache, however, depending on the product and the extent of its help files.
Driving issues
As well as the technical issues of getting the software to successfully talk to your GPS via the host PDA, there are the more prosaic considerations of mounting the PDA so you can see it easily while driving, and keeping both it and the GPS add-on powered for the full length of your journey. You'll need to be able to see your PDA screen without taking your hands off the wheel, and you're safest if both it and your GPS device are powered from the car's cigarette lighter, to keep the battery charged.
Most, but not all, GPS kits come with car mounting accessories. The Bluetooth units don't necessarily need fancy mounting - they can easily be attached to the dashboard with Velcro. However, you'll want to mount the PDA securely and within both plain view and easy reach. Most kits come with a DC adaptor designed to power a PDA, but not all do. We've listed this in our table of popular choices. As most Pocket PCs will only last a couple of hours unplugged, and have a tendency to turn off after a few minutes too, powering the PDA is the priority. Navman's Bluetooth GPS devices notably only have one power output from the car adaptor, although the GPS will work for up to 30 hours continuously on one set of standard AAA cells, so you can leave it on battery power.
So long as there's a clear view of the sky through the windscreen, the GPS should work. But with the weak transmissions from GPS satellites (see How GPS works), you may find that athermic glass, fitted in some newer cars, will block the signal. This isn't a terminal problem, however, as many of the latest devices have sockets for an external antenna, which can be placed outside the car.
A final consideration is memory requirements. Some bundles include a memory card with the maps pre-installed, but if not, then purchasing at least a 128MB module for your PDA is an absolute necessity. For Navman products, this will just about fit the entire UK map set, although some European countries are larger and some GPS products take up more space for their mapping data, making 256MB more realistic.
On your bike: GPS outside the car
An in-car navigation system based on a PDA will help prevent you having to sit outside a Little Chef scratching your head over a Great Britain road atlas, but for tougher environments where getting lost could be a serious hazard, a PDA is fatally flawed. In these circumstances a dedicated handheld unit is a far better option.
The main design considerations for all-in-one dedicated units are that they have long battery life, can keep track of where you are at all times, don't randomly hang up and need resetting and don't stop working as soon as the first drop of rain falls. Current PDAs are consequently not an option. And despite their better battery lives, often extending beyond 12 hours, separate Bluetooth GPS units usually switch themselves off if the Bluetooth connection is lost - in other words, if you switch the PDA off to save juice. Consequently, the unit can't keep track of where you've been, making retracing your steps via the device impossible.
Because of this, the market for standalone, dedicated GPS units is as healthy as ever, although they do still tend to be a little chunky compared to the CompactFlash-sized receivers that slot into PDAs. That said, the smallest units around at the moment, Garmin's ForeTrex and ForeRunner series, weigh less than 75g.
Although GPS only offers the ability to determine your position, a little bit of device intelligence can translate that into your distance travelled, your current and average speed, and direction of travel. This makes the system useful for more things than simply working out where you are at a given moment. Almost all handheld devices have the ability to remember your track over time and sport a data output that will allow you to upload or download tracks and routes to PC. You can use this in conjunction with third-party software, such as Memory-Map (www.memory-map.co.uk) or Anquet Map (www.anquet.co.uk), to overlay the results of your wanderings on an Ordnance Survey map of the area, or pre-calculate a route and upload it to the GPS as a series of waypoints; the GPS will then guide you along your route - all you need to do is follow the arrow. As long as your batteries don't die and the satellites are available (and there's no guarantee of this - see The history and future of satellite navigation), it's essentially impossible to get lost.
If you're a walker though, remember that for GPS to determine your direction of travel you actually need to be moving. A receiver calculates your direction by taking two or more successive position plots; if you've stopped this can't happen, and when moving very slowly the limits of accuracy of the plots can lead to false direction data. To combat this, anyone needing to know the right direction when they're stationary - when stuck on a mountain plateau in a blizzard, for instance - can buy a unit with a separate integrated electronic compass. These operate in the same way as a traditional compass, by sensing the earth's magnetic field lines. Models like Garmin's eTrex Summit (www.garmin.com) and Magellan's Meridian Platinum (www.magellangps.com) sport this feature. The eTrex Summit also has a barometric altimeter, which is accurate down to about three metres: better than the altitude fixes given by GPS alone. Accurate altitude helps you to use the contour lines on Ordnance Survey maps to find your position with more precision.
GPS can be a great training aid for athletes too. For running or jogging, Garmin's Forerunner or Timex's Ironman GPS watch will keep track of your performance and provide you with pace cues based on your current speed. The Timex has a separate GPS receiver unit that straps to your upper arm and communicates with the watch via a wireless link, whereas the Garmin Forerunner series (there are currently two models, the 101 and 201) includes all-in-one units that simply strap to your wrist.
Cyclists can get all these benefits too; the eTrex and Geko series GPS units having an optional handlebar mount. For long tours, the battery life of 8-12 hours is a disadvantage compared to standard cycle computers that last several years on a single lithium button cell. But a standard bike computer can only tell you how far you've been and how fast. A GPS device can do this - and do it more accurately - as well as navigate for you, plus there's no messing around attaching wheel sensors and magnets to the bike: just pop it on the handlebars and off you go.
Conclusion
PDAs remain the simplest way for many people to start using GPS, and this market has very much come of age. It's inexpensive to buy and relatively easy to set up, and from our experience reliable enough for everyday operation. The majority of devices, however, are still essentially non-connected - they work with static map data. Even more exciting possibilities are around the corner, such as when the maps become dynamically connected to roadwork and traffic information.
We're already seeing the first steps in this direction with the Wayfinder service, and the LiveWire demo included with HP's latest iPAQ Navigation System 3, which downloads traffic data via GPRS. CoPilot Live, on the other hand, integrates messaging into the GPS navigation application, so you can receive text messages on the PDA from a desktop PC, for example, with a change of address. But even without these futuristic add-ons, GPS navigation with your PDA will mean you need never be lost again.
Author: James Morris and David Fearon
GPS: Use it (or get lost)