GPS navigation overview: Maps go digital

What else can my mobile phone do for me? It almost makes you wonder if there still are people out there using their phones for calling and texting only. We've seen oblique, farfetched and elite options gradually become make-or-break for mobile phone buyers. Handsets with GPS support are enjoying a growing interest lately. More and more people are considering switching to a device with built-in GPS or buying an external receiver to use with their current phone. We are getting tons of requests for a detailed look at the issue, so we decided it's about time we did something about it. In this article we try to shed light on the capabilities a Bluetooth GPS receiver gives you.

The chosen two

Now, this is not the focus of our review but it's important to make a few points about different GPS receivers. We tested two devices produced by one of the world's most popular manufacturers HOLUX. Holux M1000 and Holux GPSlim 240 are the lucky participants in our test. We decided to go for them mainly because a comparison like this makes a clear point about the differences between the most popular GPS chipsets: the SiRF Star III and the quickly catching up MTK MT3318. The latter is pitched for its one of kind power saving properties providing unbeaten battery lifetime. As it turned out, it lives up to its reputation but we'll come back to that a little later in our article.

Holux GPSlim 240 uses SiRF Star III chipset, while Holux M1000 comes with MTK MT3318

First impressions

One thing you can't help noticing when comparing the two Bluetooth GPS receivers. The M1000 is more than twice the size of GPSlim 240 and of course it weighs a good 50% more than its competitor. Don't get us wrong, it is still compact enough at 65 x 43 x 17.6 mm and 53 grams of weight. Still, the GPSlim is well worth its name. After all, 64 x 22 x 15 mm is about the size of a car key and 35 grams is an insignificant weight.

The GPSlim240 is way more compact than the M1000

The two devices are very similar designwise - they have oblong shape with three LED indicators at the top and a miniUSB port on the side. The LEDs are easy to use status indicators. There is a dedicated LED for the battery status, Bluetooth connection and, of course, GPS data. The latter blinks when the receiver has locked to enough satellites to provide a (more or less) exact location. If the signal is not strong enough though, the LED will produce continuous orange light.

A nice feature of the larger M1000 is that its battery can be replaced, which means that you can have as many batteries as you like to go endless hours without needing to charge. As our experience with the M1000 showed however, you are very unlikely to ever need that. The advertised 23 hours of battery life is not too far from what you get in real-life usage. The by far smaller GPSlim 240 receiver, on the other hand, is supposed to only last 8 hours and so it does. OK, "only" does sound highly ironic. 8 hours is in fact a lot of time, more than enough for almost any situation. We have to mention here that both receivers come with a car charger adapter, in addition to the USB charger cables they have.

The replaceable battery of M100

Performance

Enough small talk about design, we now focus on what really matters - the performance of the two GPS receivers. The differences we came across are conditioned by the completely different chipsets used. The initial start time (the time elapsing from powering the receiver and achieving satellite lock) of the M1000 is quoted to be shorter than that of GPSlim 240, but we'll have to disagree. In fact, the GPSlim 240 found enough satellites for a GPS downlink in much shorter time on almost every occasion leaving the M1000 biting the dust. On the other hand, M1000 managed to lock on more satellites than the GPSlim 240, and was able to provide coordinates (although not as exact as usual) in more complicated conditions than its rival. It had no problem when positioned under solid roof at about 4 meters from the nearest window, whereas GPSlim 240 lost contact at about half that distance. This however is not that important, as it is not very likely to use your GPS receiver indoors.

In terms of data refreshing, the tinier GPSlim 240 communicates with the connected phone far more often refreshing the coordinates on the screen. The power-saving architecture on M1000 only does that once in a second. In real life usage you are highly unlikely to feel any significant difference. Besides, the accuracy of both devices is very good and that's what really matters. An interesting bug we noticed in the GPSlim 240: it loses signal upon a rapid change of speed - mostly when breaking suddenly at high speed. This of course happens for less than a second, so you are unlikely to even notice that when using it for in-car navigation.

Anyway, if we have to choose we will probably go for the Holux M1000 Bluetooth GPS receiver, despite the fact that it is quite larger, mostly for its stunning battery life and slightly lower price, though we have to admit the GPSlim 240 is just as good for the job.