Navicore Slim SiRF III Bluetooth GPS Receiver

Navicore Slim SiRF III Bluetooth GPS Receiver

a.k.a. Holux GPSlim240 Bluetooth GPS Receiver

So .. what is it? It's a GPS receiver that's the size of a pack of chewing gum with a built in Bluetooth connection that runs for 8 hours between charges. Why do you have one? I use it in conjunction with my mobile phone as a portable GPS system. Using a Perl script available from the Mobile GMaps website, I've cached street and satellite map tiles for the whole (well, most) of London at two different zoom levels that provide a good overview of major roads and individual street names. When you live in a city with a random road layout, an arrow on your mobile phone pointing you in the right direction is really handy. Try this link to see where I am, or at least where I was ;-)

Tell me more

This unit comes with a USB lead, but it does not work over USB - the lead is purely for charging the internal battery. If you plug the lead in and switch the unit on, Linux complains about a broken cable and Windows just complains. The only available connection is over the built in Bluetooth, so make sure that you have a working Bluetooth setup before buying one.

The device is simplicity itself to use, you just slide the switch to "ON" and wait for the satellite lock indicator to start flashing. Once that's done, you can connect to the device from your favourite piece of software. I use Amaze for directions, and Mobile GMaps for general GPS stuff. Mobile GMaps supports the use of offline maps stored on the phone so that you don't end up with an excessive data bill from your mobile service provider. It's a really neat piece of software and well worth checking out.

Does it work?

Yes - it works really well all things considered. I get a satellite lock within 15 seconds from a cold start at home, and the fix itself is very accurate - usually around 2 metres, depending on the number of satellites that are visible at the time. It works reasonably well in heavily built up areas (central London), but does occasionally go a little nuts if it has trouble getting a proper lock (e.g., if you go indoors), but that's pretty much par for the course with any GPS receiver.

The good:

• Generates NMEA sentences
• Works indoors (sometimes)
• Very small
• Good battery life
• Charges over USB cable
• Just works

The bad:

• LED indicators for Bluetooth and GPS lock are behind the translucent case and are almost impossible to see in daylight
• Doesn't work over USB
• Battery isn't replaceable unless you pull the case apart and find a replacement cell that will fit