Understanding GPS Features

Not all GPS receivers are created equal and, to be able to discriminately differentiate between different models, we need to understand the technical speak used.


The screen is usually what you notice first when we use a GPS receiver — and you’ll be looking at it lots of time in real use. So you want one with a good resolution.

The dimension in inches refer to the diagonal length. The standard is currently 2.5 inches, with some newer models sporting a wider screen. Generally, a wider screen is easier to read and see, and may be a good choice if you have difficulty reading the smaller screens.

The screen resolution is stated in pixels, e.g. 320×240 pixels. This is the number of dots that will make up the image on screen. The more pixels, the more detailed the image can be, and so the easier the screen is on the eyes.

These two screen specifications determine the quality of the screen. It is not enough to have a wide screen if the increase in width is not matched by a corresponding increase in resolution (otherwise the pixels are just distributed across a wider area, which may make the image appear less detailed).

Most GPS receivers have color screens and the standard is 64,000 colors, which is more than enough. I would not sweat on this specs. You want a clean and simple map to be displayed for easy viewing — not a pointillist painting.

However, if you want to use your GPS receiver also as a photo album (some higher end models allow you to do that), you may want to be able to display lots of colors.


Maps usually come preinstalled in the firmware. Base maps may cover only the USA or all of North America, i.e. USA and Canada. Some models also include maps of European countries.

As mentioned, maps may come preloaded or available on a Secure Disk (SD) memory card that you insert into the receiver. I personally prefer maps preloaded into internal memory, leaving the SD card for other uses such as playing MP3, viewing photos, or loading maps from other countries (if your GPS receiver has those options).

The quality of the map(s) is part of what makes your GPS receiver useful. If a map is outdated, you may not be able to navigate to a new area in town. Manufacturers usually provide map updates on their web site for download. You would then upload the new map(s) into your GPS receiver.

When purchasing a GPS receiver, it is therefore a good idea to find out which year’s map is included in your device. If the map is one year old, it will most probably still be useful unless you intend to be driving in areas that have been newly developed.

Sometimes, new models are introduced with last year’s map, perhaps because the newer map has not been finalized yet. You can opt to wait for the new map to be made available in new devices (though you cannot assume that just because a new map is now at last available that the newest GPS models will automatically have them — you need to verify) or buy now and upgrade the map later.

Manufacturers used to provide free map upgrade if you bought their latest models with last year’s map. But it seems that they are not doing that anymore and so you need to check unless you don’t mind paying for the map upgrade.

GPS Chipset

Having a good up-to-date map in your GPS receiver is only part of the equation in having a useful GPS.

What if the map is accurate but the GPS cannot place a fix on your current location and/or send you 100m from your intended destination? Don’t laugh! Some units have been known to do that, especially when Geotracking. To be fair, GPS receivers are generally really accurate when dealing with maps of major cities.

The chipset in your GPS receiver will also determine how fast you can acquire a fix on your current position. Everytime, you turn on your unit, it has to connect to the satellites and locate you correctly. You want a chipset that does this f-a-s-t! Look for a receiver equipped with the SiRF Star III Chipset.


All GPS receivers are capable of giving voice directions such as, “Turn right in 100m.” These are prerecorded speech fragments and help tremendously in making sure you don’t miss your turn.

But what happens if, at an approaching intersection, there are more than one possible roads, e.g. a number of small side roads close together or two roads that fork away? Which one should you take?

A feature that is quickly becoming popular in some higher-end models is “Text-To-Speech” which goes one step beyond voice directions. The receiver will read the street name you are supposed to turn into so that instead of simply saying “Turn right in 100m” followed by “Turn right” when you come to the intersection, it might say, “Turn right in 100m” followed by “Turn right at Swansea street.”

3D Display & Turn Arrow

I would strongly encourage you to consider a receiver with 3D Display. This is not real 3D but the map is rotated slightly to give a 3D look to it so that you feel like you are going in the right direction. Couple this with an arrow that shows you where you are supposed to make the next turn and you get a confident feeling that you know what to expect next.

Do take the time to verify that your GPS receiver does have the turn arrow feature because not all do. All receivers will draw a straight arrow to tell you the direction you’re going — which is straight ahead anyway since the map is oriented so that you are always going straight ahead — but not all will actually draw the turn arrow.

POI Database

A Point-Of-Interest (POI) Database will highlight interesting places along your route. The POI Database typically contains millions of POIs covering the whole of North America. This is standard for all GPS receivers and again it all depends on how up-to-date the database is kept. Great if you are visiting a new city or driving along a scenic route.


A Waypoint is a location you want to drive to or through. So your current starting location and your final destination are two Waypoints. For example if the GPS suggests a route that takes you from point A to point B and takes street C, you may set a Waypoint on another street that redraws the route to avoid street C, say a particular busy street during traffic rush hour.

If you need to stop at multiple locations along your route, you want to make sure you can enter more than one “via” point (another term for Waypoint). Some models will accept only one while others allow multiple or even unlimited.


Suppose you are driving, following the route the GPS receiver has suggested and you see an interesting shop you decide you may want to visit later.

A Trackpoint allows you to mark your current location on the map so you can easily drive back to it later. Some models do not have this handy feature while others allow multiple or even unlimited trackpoints.

Bluetooth Hands Free

As you approach your destination, say a city, Points of Interest show on on your screen: a restaurant, a hotel, a gas station.

If you need a place for the night, just touch the screen (most are touch sensitive) at the hotel and your cell phone starts dialing using the number associated with the hotel. This hands free dialing allows you to book a room before you even set foot in your hotel. Ditto for phoning a reservation at a restaurant ahed of time.

Traffic Info & Rerouting

With some higher-end models, you can optionally subscrobe to a local traffic advisory that will beam up-to-date traffic info to your receiver so it can reroute you if heavy traffic is encountered on one of your route.


If you just intend to use your GPS receiver in the car, you just want to ensure it has a reliable mount that allows you to set it low enough on the windshield so it does not block your view.

However, if you also intend to use it with you, then consider a portable model that is slim enough to be pocketable.

A portable GPS receiver can have features that calculate time to arrival (again not all models have this feature, forcing you to make the maths in your head) depending on whether you are driving, on a bike or walking.

This is great for visting a city you are not familiar with and you do not intend to drive once you arrive there, say for a conference. Your portable GPS receiver will guide you to the conference location, a restaurant for lunch, a movie theatre for the night, and take you back to your hotel.


I mentioned earlier that some models include the ability to play MP3 and video, display photos or connect to your Ipod. These are options that you may or may not care about.

I suggest that you leave these options as “nice to have.” If your GPS receiver does not do its main function well (take you from point A to point B), then these options are irrelevant.


So, as you can see, selecting the GPS receiver that is right for you involve having to make a number of choices. This is because you probably will not find all your desired features in one model and so you will have to prioritize which features are “must-haves” for you.

I suggest the following as a starting point for your list of “Must-haves”:

  • a fast GPS Chipset
  • clear, bright screen that does not wash out in bright sun
  • 3D display with turn arrow
  • up-to-date maps of North America (and/or Europe)
  • Text-to-Speech

You can add other features to this list depending on what is important to you.

Learn more about GPS receivers and compare models: