By CNET.com, with contributions from Michael Tan
27/07/2007
URL: http://asia.cnet.com/cartech/0,3800004381,62029537-5,00.htm

Before we dive into the types of navigation systems and buying advice, it's always good to get a little background on the technology and have a basic understanding of how it works. Originally developed in 1973 by the US Department of Defense for military purposes, the Navstar GPS network consists of 30 satellites orbiting the earth every 12 hours, and five ground stations that monitor the satellites' position in space and operational status.

I spy
In order to accurately determine your location and other data such as current and average speed, directional heading, and elevation, GPS devices use a receiver to acquire signals from at least four of these satellites. This is known as a 3D fix, and it's why GPS antennas require an unobstructed view of the sky to work correctly.

Armed with your precise latitude, longitude, and other location data, the GPS receiver can overlay this information onto map files stored on the unit, revealing your current position on the map as well as where you've been. Since the receiver is constantly recalculating your position relative to the satellite's position, the GPS unit can track your location in real time.

Time to lock
A typical GPS device contains a 12-channel receiver and an antenna to capture satellite signals, as well as a CPU to process the data. The quality of the receiver and your geographic location will determine how long it takes the device to acquire a 3D fix. For example, it's harder for the receiver to lock onto and hold a signal if you're traveling through a dense forest or an urban area with tall buildings.

The first time you fire up your GPS, it collects certain satellite information to determine your whereabouts. In this state known as a cold start, the receiver is essentially blank and needs to know what time it is, where the satellites are in their orbital patterns, and where it is in relation to the satellites. Most systems take around 1 to 2 minutes to acquire a 3D fix during a cold start, while some can take a few minutes. Thereafter, it can take as little as 3 to 4 seconds to lock in since the unit already has your coordinates and a general location of the satellites.

A good receiver will instantly recover from a complete signal loss when you drive through a tunnel, for instance, while weaker units will require more time to reacquire a 3D fix. In some cases, you'll have to stop the car to give the receiver a chance to lock on to the requisite signals. Recent developments in technology has made it possible to shorten the lock on time or even render temporary signal loss irrelevant to a certain degree.

Location of antenna key
How well a GPS unit works in your car depends on the location of the antenna. If your vehicle has a factory installed in-dash unit, chances are the antenna is integrated into the dashboard in a place where it has an unobstructed view of the sky, which is ideal. Many portable models are designed to be positioned directly on the windshield via a suction cup-mounting device, giving the antenna a wide sky view. There are also addon antennas available for GPS units that allow you to keep the receiver close to the front seat for easy viewing without sacrificing signal quality.

Mike Tan is a car fanatic who, truth be told, spends way too much time for his family's own good on motoring forums and inside cars. He has been tinkering with GPS devices "for a long time" and never leaves home without one.

Driving with GPS

In-car navigation isn't for everyone; the price alone will cause many people to forgo this technology in favor of the good old street directory. Moreover GPS is usually dismissed as not being necessary in the entire 644sq km that is Singapore. However, if you have a bad sense of direction, or just can't get your map oriented in the correct direction, GPS can make the driving more enjoyable and stress-free, with fewer fights with your spouse who's usually the unwilling navigator. For those who drive to Malaysia a lot, a GPS could lead you to marvelous food places or major attractions effortlessly, greatly expanding the number of destinations while optimizing your traveling time and distance in unfamiliar territory.

The Asian disconnect
Note, though, that neighboring Asia such as Thailand, the Philippines and Vietnam, suffer from a lack of maps to use. Hence, we will not be covering those countries in the region.

As a business tool, GPS can be a tremendous aid for field service or delivery personnel or if you frequent different cities on business trips. Some new systems even let companies track their vehicles in the field. As the technology advances and we start seeing more real-time traffic-report capabilities, it will be easier to avoid the bumper-to-bumper grind with the GPS automatically suggesting and recalculating alternate routes with less traffic.

GPS navigation not foolproof
Like any technology, GPS isn't foolproof. You still have to rely on a strong satellite signals to pinpoint your position on the planet. So if you're driving in a heavily wooded area or an urban jungle, you must have a good idea of where you've been and where you're going as you may no longer be tracking your actual location. It's important to remember that GPS is a navigation aid that will enhance your driving experience, not an automatic pilot. Still, if you're prone to wrong turns and constantly getting lost, this technology is for you.

Nearly all vehicle GPS systems come with a warning stating that drivers should not enter information into the unit while operating the vehicle. As a safety precaution, some models lock the onscreen keyboard and the touchscreen capabilities while the vehicle is moving. Unless the device has the ability to accept voice commands, searching and creating routes while in motion should be left to a passenger, even if it comes with a remote control. With voice-guided driving directions, the driver doesn't have to glance at the screen; instead, it's a matter of waiting for the voice prompts to get you moving in the right direction.

Other than helping you get from place to place, automotive GPS systems offer little else in the way of entertainment, although we're seeing more models integrate such features as MP3 players, image viewers, and audiobooks. Also, off-road drivers will find GPS useful for exploring unpaved terrain and creating their own rendezvous points and trails based on their latitude and longitude coordinates.

Special considerations in Singapore

Singapore is a small, highly urbanized country. Because of this, there are some special considerations of note before considering using GPS in Singapore.

High density of tall buildings
Singapore has tall buildings both in residential and commercial areas. Tall buildings block GPS signals from reaching your device, and these result in a high incidence of signal loss or signal degradation, resulting in either inaccurate positioning or total positioning failure.

Singapore has a relatively organized road system
Singapore's road system is relatively systematic, with good signage. And being relatively small, a GPS may not be worth the cost or time investment to learn for many drivers. However, Singapore's immediate neighbor, Malaysia, has a wealth of roads and attractions which may not be so easily accessible. So frequent visitors to Malaysia may find GPS incredibly useful.

Free Maps compatible with certain units
Singapore and Malaysia are lucky to have very well-established community maps available for free, which you can find here. Unfortunately, these maps work properly only on certain GPS devices, including most dedicated Garmin units and most Windows Mobile and Palm devices (e.g. PDAs) running the Garmin emulator software. Recently, owners of the original Mapking software could also use Malsingmaps without requiring the Garmin emulator software. These free maps are updated very often by the online community, with very accurate points of interest (where to eat the best beef noodles in Malacca, for example), making them at least competitive with the best commercial maps in some areas, often better in most other areas.

Singapore is a small market
Hence, commercial map support for Singapore is relatively expensive and may not be as updated as the Free Malsingmaps version. BMW, for example, charges a cool S$835 for a Singapore map update, and no subscription plans are available.

Some GPS devices boast the ability to use the Wide Area Augmentation System (WAAS)
This is a system of satellites and ground stations that provide GPS signal corrections, giving you even better position accuracy, in fact, an average of up to five times better. WAAS is unfortunately available only in North America, so it may not be worth shelling out the extra cash for something which cannot be used in Singapore. If one drives in the US a lot, WAAS compatibility may be worth considering, though.

Fast pace of development in Singapore and Malaysia
Rapid changes in the road transportation for both Malaysia and Singapore make it quite important to be able to maintain updated maps every six months or so to remain useful. After all, it is the new or unfamiliar roads which most people need guidance, not the old, well-established routes.

Some useful pointers
Because of these special considerations, the following tips may come in useful:

1. If buying a GPS device that is not factory-fitted into the car already, it may be worth seriously considering getting a Garmin-branded unit which can use the free community maps from Malsingmaps.

2. An advanced feature called "Dead Reckoning" may be desirable in Singapore. Dead Reckoning is a method of estimating one's current position based upon a previously determined position, or fix, and advancing that position based upon known speed, elapsed time and course. With Dead Reckoning, once the GPS signal is lost, the device can calculate your position to a fair degree of accuracy based on your last known location before signal loss while waiting to regain the GPS signal lock. A GPS device with Dead Reckoning capability will be able to offer more seamless operation in Singapore, but you will have to pay more for it. Given the frequency of signal loss in urban areas or within residential areas in the Republic, this is worth serious consideration.

3. Given the existence of extremely detailed and usable maps for free from Malsingmaps, factory-fitted GPS navigation not compatible with Malsingmaps may not be a sterling value proposition, unless one can tolerate an increasing number of discrepancies as the Singapore and Malaysia roads change more and more compared with the GPS maps frozen at the time of the car purchase.

4. Because of the frequency of signal loss, quick re-acquisition of signals will be very useful. Signal re-acquisition speed depends on several factors, including the quality and size of the receiving antenna and the sensitivity and power of the Satellite Signal Processor chip, the heart of the GPS device. Recent products like the SiRFstarIII GSD3t use a combination of advanced GPS signal acquisition strategy and high sensitivity to achieve an extremely fast GPS signal lock.

5. For a short list of GPS maps available for Malaysia and Singapore, this page is helpful with some short comments.

Addon or in-dash GPS?

Factory option
Professionally installed
Portable units
Handhelds and addons

What features should I look for?

Display
Maps
Form factor
Navigation features
Accessories

Loading maps

Virtually all vehicle GPS systems come with maps, although not all of them are detailed street-level maps. Most in-dash models use optical media, such as CD-ROM or DVD-ROM discs that come directly from the manufacturer with maps preloaded. In some cases, these discs are part of the package, but some vendors require that you purchase them separately or subscribe to a plan that provides updated discs on an annual basis. DVD media containing detailed maps of Singapore are typically priced in the S$1,000 range.



Top-of-the-line portable models provide comprehensive street-level maps on a hard drive, so you never have to worry about losing detailed coverage when you travel outside of a map region. This seamless coverage is what makes this type of GPS system so popular. Units that use removable media, such as flash memory cards, can hold as much detail as the memory card allows. For example, the Garmin Nuvi 600 series, a PDA/GPS device designed for use in a car and on foot, can be purchased without preloaded maps. Instead, it has some internal memory and can accept SD cards to hold detailed map regions.

Do invest in some memory cards
A typical Malaysia and Singapore map can be held in a 256MB SD card. If you want to cover more ground, like Australia, you'll have to purchase extra SD memory and preload the necessary regions before hitting the highway. With the price of SD media being so low nowadays, SD card devices are ideal whether for the normal user or the global traveler.



The least expensive dedicated GPS units will come with base maps of the world, which include major interstate roadways and highways. For some travelers, this is sufficient, especially if they simply want to track their progress on long-range trips. If the unit has enough memory or a slot that accepts flash media, you can add detailed maps as you go. It's rare to find an automotive GPS system that relies on internal memory to store maps, since flash memory offers more flexibility.

Be prepared to spend time loading
Loading maps onto your GPS unit can be a time-consuming process. First, you'll have to load the mapping software on a PC and connect the GPS device to your computer. Depending on the software, you can select predetermined regions to upload, or you may have to pan the map and create your own regions, which requires constant adjustments to create a region that will fit on your memory card. In some cases, you have to visit the vendor's Web site or the community map site to download maps to your PC, then upload them to the GPS unit. Both methods may require an unlock code to access the maps, which usually carries an additional fee and can cost hundreds of dollars, depending on the vendor.

Route guidance

The biggest advantage that in-car GPS devices have over paper maps is the ability to create electronic routes, complete with turn-by-turn directions and, in most cases, voice-guided directions. Depending on your GPS unit's feature set, it may be necessary to plot a route on your PC before heading out on the highway, although most current models contain enough memory and map storage for on-the-fly routing. Creating a route involves entering a destination and letting the system determine a route from your current location.



Almost all the of the high-end vehicle navigations systems utilize touchscreen technology to make entering destinations and addresses as easy as possible, and a few select models let you access the onscreen keyboard via a wireless remote control. Some of the newer (and more expensive) in-dash models now feature voice-activated input as an option, such as the 2006 Honda Civic Hybrid, where you train the system to accept spoken commands.

Calculating the routes
Routes can be calculated any number of ways, depending on your preference. You can ask for the fastest or the shortest route, where the fastest route calculation is biased toward highway use and the shortest route includes small roads which may be congested. Needless to say, these functions are meaningful only if the roads are relatively uncongested or if traffic data is made available to the GPS. To date, Singapore has no such traffic data available yet. You can also tell the system to avoid certain routes, such as toll roads and interstate highways. This is particularly helpful if you know that a stretch of road is extremely congested all the time, under construction or is closed for some reason.

Once the system has your starting point and destination, it calculates the best route according to your specifications, then displays it on a map, highlighting each segment of road along the way. The map view is typically a 2D view, although most of the latest systems are capable of displaying 3D and aerial map views. You can also view the directions in text with details such as distance between turns and estimated time of arrival based on your current traveling speed.



Ideally, the system is capable of giving voice-guided directions, which lets the driver concentrate on driving without having to glance at the screen. With voice directions, it's almost impossible to get lost or miss a turn because you are alerted of your next maneuver well before you actually have to make it. The voice prompt typically warns you of your next turn immediately after you've completed a maneuver, again as you're heading toward the turn (to give you enough time to safely change lanes), then one more time as you approach the actual turn or exit ramp.

Newer systems such as the Garmin StreetPilot c580 feature text-to-speech functionality, which actually tells you the name of upcoming streets. If you still manage to miss the turn or deviate from the original route, the system will calculate a new route based on your present location.

Not all GPS systems are created equal
Of course, an in-car navigator is only as good as its receiver, and since all GPS systems are not created equal, some are more accurate than others. The same goes for mapping data and directions; a good system will have up-to-date maps that can differentiate between one-way streets, dead ends, and so on. As a rule of thumb, GPS systems that use commercially available NavTeq or the free community-driven Malsingmaps digital maps are among the most accurate for mapping detail.