Windows Phone Thoughts: Out of the Blue - BT-338 Bluetooth GPS Receiver from GlobalSat

Nicely Equipped
GlobalSat includes a complete set of accessories for the BT-338 right in the box. That includes an international travel charger with a voltage converter. It has a europlug built in and adaptors for British Standard and US spec plugs. A car charger is also provided, and it features a y-cable that allows charging of the GPS receiver and the Pocket PC simultaneously.


Figure 3: GPS Information Utility

A GPS information utility is also included. It provides information about the satellites that have been acquired.

So, Does It Live Up to the Hype?
I don’t have a GPS receiver with the SiRF Star II chipset. However, my reliable RoyalTek BlueGPS has roughly comparable performance using a RoyalTek chipset, so I used that unit as the point of comparison.

First, I tested the time that each unit took to acquire enough satellites to get a fix. I would classify this as a “warm start” test. This means that the GPS has nearly complete information from its last fix and all it needs to do is to verify that the information hasn’t changed. I used my Loox 720 running OnCourse Navigator 4.

I tested the BlueGPS first. It took 20 seconds for OCN to report a usable fix with 6 satellites. Next was the BT-338’s turn. It took only 9 seconds for a 10 satellite fix.

Then I tested sensitivity. Prior experience with older GPS technology makes the importance of this characteristic clear to me. Years ago, I did some hiking in wooded areas using a Garmin eMap (a dedicated handheld GPS device). The unit would frequently lose its satellite lock when I walked under thicker foliage.

Now I didn’t try the same hike with either of the Bluetooth GPS receivers, but indoor reception seemed to be a reasonable alternative for a sensitivity test. I took the receivers to a central indoor location, as far from any windows or exterior walls as possible. The BlueGPS struggled under these conditions, going from 6 satellites down to 2. This means that it lost its fix, since a fix requires 4 satellites. On the other hand, the BT-338 breezed through this test, keeping its lock on 9 of the 10 satellites that it acquired under more optimal conditions. These are admittedly non-scientific tests, but I feel that they reflect the experience that the average end user can expect with these GPS receivers reasonably well.

On the road, the BT-338 performed admirably, acquiring satellites very quickly and maintaining the fix through several hours of driving. I didn’t stress test the battery life, but given that my BlueGPS is good for about 8 – 10 hours on a single charge, I feel that the claims of 15 hours or more are definitely in the ballpark.

Conclusions
The BT-338 lives up to its promise… greater speed and sensitivity along with lower power consumption than previous generation Bluetooth GPS receivers. And its price is competitive with several of those previous generation units that are still available. If you’re in the market for a GPS Bluetooth receiver right now, my take is that the BT-338 should be right at the top of your list.

Doug Raeburn is a data architect specializing in data warehouse design. He lives in Pewaukee, Wisconsin, USA.