Products & Reviews
GlobalSat BT-338 Bluetooth GPS Receiver
Wed Apr 5, 2006 - 11:44 AM EDT - By
Table of Contents
> Overview Accuracy Conclusion
Overview GPS receivers have morphed from a hyper-expensive military tool to a common consumer item. In just the last few years GPS technology has moved from the governments clenched hands, to drivers, campers, hikers, bikers, and golfers all due to its power to show us where we are and help guide us to where we want to go. It is one of the most useful tools anyone on the go could ever invest in!
Several years ago I decided that with all the driving I did, a GPS unit would be a practical and useful device to have with me on my trips. But back in the mid 90s you needed a GPS unit as big as a brick adhered to your car dash with a antenna the size of your index finger. Back then, if those E.T. finger antennas didnt have a clear view of the sky you were pretty much out of luck trying to get a clear lock on the GPS satellites signals.
Even if you could get the necessary view of the sky, getting a signal lock took several minutes and individual city maps came on cartridges, which at the time cost upwards of $100 a pop. I remember having to buy many cartridges for Arizona, Los Angeles, and the NY Tri-State area to carry with me on trips and having to furiously juggle and sort them out and switch between them while driving. As Im sure you could imagine, this was enough to make one livid after the huge multi-hundred dollar investment in the unit itself.
If that wasnt hassle enough, you were rewarded for your expensive investment with GPS maps in black and white, accuracy down to about 100 feet and very cumbersome interfaces to plot routes.
Selective availability (government speak for the military gets more accurate data than you do, citizen) was in place at the time, which limited the data quality that civilians could grab from GPS satellites.
This situation gradually improved, until President Bill Clinton gave the axe to selective availability in 2000, unlocking more accurate positional data for public use, and improvements in GPS receiver technology soon followed. GPS displays started to appear as options in higher end cars and vans, with multi thousand dollar price tags, full color displays and talking route planning. More vehicles have in-dash GPS options than ever before, but fewer than 2% of new car buyers opt for it, not only because factory built-ins are so expensive, but 90% of the routes people drive are the same routes every day. You dont need a GPS unit to tell you how to get to work or the supermarket or your kids school, so most car buyers still look at it as an expensive frill.
These days, GPS units have advanced so much to be small enough to carry in your shirt pocket, but most still need a clear view of the sky to work. That isnt too useful unless you are in your car or out in the open, as even minor obstructions cause most receivers to fumble trying to lock onto the satellite signals.
Enter the GlobalSat BT-338 Bluetooth GPS Receiver. This tiny marvel is about the size of todays smallest folding cell phones. Its a pretty sexy little piece, measuring about one inch by two and less than an inch thick, in a slick silver casing that resembles a small wireless mouse, with three LEDs- amber, green and blue to show battery power, satellite link connectivity and Bluetooth activity respectively, next to a chrome power button.
Oddly, when connecting to satellites, the green LED is on solid and will only blink when it has established a link the opposite of what one might expect. The Bluetooth indicator behaves in a similar fashion, though the battery LED acts as one would expect, blinking only when the battery's charge is almost spent.
The GlobalSat can sit fairly securely on your car dash, kept in place by two rubber bars on the bottom and powered by a removable battery or the included 12v lighter charging cord. But this little gem is so advanced, it doesn't have to be mounted on your dash at all. It will get a clean lock on GPS satellite signals so fast, its shocking.
The GlobalSat touts and delivers cold start operation in 48 seconds, with warm and hot starts at 38 seconds and an amazing one second respectively. This is such a leap forward that it makes many other receivers look like mere toys, and it is half their size.
The latest advance in GPS receiver silicon, the SiRF Star III chipset is what makes this magic happen.
If youre shopping for a GPS receiver, avoid those with the older chipsets. Theyre a lot slower to acquire a signal lock minutes instead of seconds.
The GlobalSat also implements the advanced WAAS (Wide Area Augmentation System) explained here and pictured below:
With selective availability a thing of the past, mapping software (not included in the package) can pinpoint your location down to about three meters - less than the length of a car.
Any GPS receiver must still get a good signal from at least 6 of the 21 active GPS birds in orbit. The government was smart enough to plan ahead and send up three spare satellites in case one breaks or gets blasted out by Martians.
It does this by utilizing 20 channels (where its predecessors used only 12) again, thanks to the latest chipset, in conjunction the GPS locator built into your Treo to collect the satellite data. The BT-338 also uses more GPS signals; even the weaker signals that bounce back and forth between walls and buildings that other GPS receivers cant lock onto.
The beauty of this technology is that beyond the initial expense of the receiver and mapping software (or other GPS software that you may elect to obtain) there is absolutely no cost for utilizing the service. Thats right: GPS satellite data is totally free since those birds were put up there with taxpayer dollars. Its the receiver and some kind of software to DO something with that data that costs money.
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Name GlobalSat BT-338 Bluetooth GPS Receiver
Tested with SprintPCS Treo 650
Software used Mapopolis Navigator (not included) >
Fact Sheet & User Opinions
GlobalSat BT-338 Bluetooth GPS Receiver from