Investigation: onboard navigation

By Allan Whiting

Many dream trips have turned into nightmares over one apparently simple requirement: navigation. Adept map-readers have little patience with those who find them impossible to understand.

Navigational dramas increase in direct proportion to the size of the caravan, because it’s often difficult to find a turning area to redress an incorrect navigation situation.

I’m sure CW readers know at least one couple that has ended a journey prematurely as a result of yelling matches or stony silences that have followed direction-finding errors.

An onboard navigation system looks to be an instant cure for such situations, but some are better than others and you don’t need to buy a top-priced vehicle in order to get hold of one.

After CW evaluated the onboard units that are now standard equipment on upper-specification towing vehicles, we have come to the conclusion that in most cases you’re better off buying a lower-specified vehicle and fitting an aftermarket navigation system.

The problem with standard units is the limited range of map software included: these seem to be intended for city drivers and main highway commuters, as most have virtually no secondary roads in their mapping.

It’s quite common with these systems to drive off a main road and find the little cursor in the middle of a blank screen – with no road references! This situation is worse than having no navigation system at all.

The one major advantage of standard in-car units is the voice guidance that is part of the package, so there’s no need to look at a map to work out your next move: the calm voice of your guide tells you where to go and advises a corrected course if you make a mistake.

However, some of the after-market units have voice guidance on some maps.
If your main requirement is reliable, voice-guided navigation in major towns and cities, there are many devices that will do the job, but if you want navigational guidance for secondary and tertiary roads and major tracks in the bush, a more specialised aftermarket unit is the best
way to go.

What is satellite navigation?
Satellite navigation combines GPS location with a moving map on a screen.

The position of your vehicle on the map shows as a cursor, so you can see at any time where you are in relation to the road you’re driving on and crossroads. Some SatNav systems have voiceover instructions such as: “Take the next left turn”, or “Take the second exit from the roundabout”.

Most SatNav systems that are standard equipment in cars have very basic maps that concentrate on cities and major towns. When you drive onto a secondary road outside a town it’s common to see the vehicle cursor on a blank screen, because the system lacks enough map data.

After-market SatNav systems have more detailed mapping and can be updated easily.

To do this a GPS unit needs a partial view of the sky and some antennae do a better job than others.

The satellites were sent into orbit in the 1960s by the US Department of Defence (What have the Romans ever done for us?) and their locating abilities were enhanced when President Clinton ordered the system’s deliberate ‘fuzzing’ function turned off.

GPS accuracy depends on conditions, but is typically around 10 metres, which is ample for most vehicle navigation work. Units that have WAAS (Wide Area Augmentation Support) can improve accuracy to around three metres.

The Europeans are planning their own GPS satellite network, due to be operational within a couple of years.

What’s in the marketplace?
The navigation system scene changes almost daily, so it’s important that you check out the latest equipment and software before you buy. For example, at the time of writing you couldn’t buy finely detailed topographic maps on SD (secure digital) cards – they’re on CD only – but 1:25,000 scale topos on SD cards were made available in April 2005.

The basic navigation aid is a hand-held GPS unit. For a few hundred dollars you can buy a device that will tell you exactly where you are; log waypoints; show average speed; current speed; trip distance; altitude and sunrise and sunset times.

These units have little or no map storage capacity, but provide latitude and longitude data that allow the user to pinpoint a position on a map that has lat’ and long’ co-ordinates in the margins.

Some of these units can be connected to a laptop PC, which can be loaded with map data. The problem with this arrangement is that the PC needs to run continually and be stowed where it is visible and, at the same time, remain insulated from vibrations.

There are vibration-resistant laptops, but even with these there’s still a problem of where to fit the unit.

The next step up the navigation system ladder is a larger, hand-held unit with in-built map storage capacity. The better versions come complete with map software such as DiscoverAus and Hema’s Great Desert Tracks. These maps are adequate for most caravanners.

The top-shelf hand-helds can be ordered with marine charts as well. Pricing for these units is typically in the $700-$1400 bracket.

Less rugged than hand-helds, but with a larger screen, are the latest PDA (personal digital assistant) devices.

Some PDAs come with in-built GPS antennae and for others an external GPS antenna is an option. Bluetooth PDAs can communicate with a GPS antenna, without cable connection.
Because PDAs are generally designed for indoor use, they need to be mounted in a position where dust, heat and water won’t affect the units.

Some PDAs can be protected by specially designed cases. Pricing for PDAs is typically $800-$1500.

The next level is a dashboard display screen navigation system that looks and sounds similar to the standard units available in luxury cars. These units have larger screens than hand-helds and are purpose-built for dashboard mounting. Pricing for in-car units is around the $2000 mark.

The process of selecting a navigation system is an honest assessment of your real needs. Do you need it to be portable for hiking?

What maps do you want? Will the same unit be needed for boating as well as driving? Do you need a ‘talking’ unit or can you see the screen safely?

Can you rely on relayed navigation instructions from your co-driver?

The availability of regional maps has greatly improved and it’s possible to buy detailed maps of specific areas, such as the Victorian High Country or Cape York.

These maps make it unnecessary to buy expensive and bulky topographic maps of offroad regions, unless you plan to go hiking or remote area 4WD driving.

For all your GPS needs, check out these brands:
Next Destination Pty Ltd: freecall 1800 644 033.
DiscoverAus: (02) 9999 2313, fax (02) 9999 6716; www.gpsoz.com.au
Hema Maps (Hema’s Great Desert Tracks): (07) 3340 0000, fax (07) 3340 0099; www.hemamaps.com
Uniden: (02) 9599 3355; www.uniden.com.au