Globalsat BT-328 Bluetooth GPS Receiver Review

location based services


The Globalsat BT-328 is aimed at being an entry level Bluetooth GPS receiver for those that either don’t want to pay for its big brother the Globalsat BT338, or are looking for something a tad smaller. Physically, the BT328 is about 20% smaller than the BT338, has a hole to attach a lanyard/strap, and appears to only come in the standard white with grey colour scheme. The new BT328 sporting white and grey, next to its slightly larger but higher spec big brother the BT338. The size difference is really only in their height.You are so like your brother!Operationally they are identical… and that is a good thing as you can read in my BT338 review, they both have 3 LEDs (orange for charging/charged indicator, green for GPS fix or not, blue for Bluetooth connected or not) and a single on/off button. Connecting the unit to my laptop and to my Pocket PCs was a breeze… using your devices Bluetooth manager, you find the GPS, and pair with it with the “0000” password. Shame the discovered identities of the devices are not a tad more descriptive… the newer BT-328 is the one with the id BT-GPS-32E84F (go figure!).From there, you simply tell your mapping / navigation software to listen on the appropriate serial COM port, and that’s it. I was using Memory-Map so I set it up to monitor the appropriate COM port (the same process for use on a notebook or a PDA)Here I chose the standard NMEA, selected the COM6 port the GPS was connected to. I would have expected the SiRF option to work, but it did not using the defaults.But inside you are differentSo, setup and operation amongst these two units is easy and consistent. But the main difference is the GPS chipsets they use. The BT328 uses a SiRF GSC2 chipset which is not only smaller, but requires less power. As such, this unit is stated as being able to deliver 16 hours of continuous operation from its 1300 mAh battery. The BT338 with the fantastic SiRFStarIII chipset claims 17 hours of operation but uses a 17000 mAh battery.I did some looking around to see exactly what this new GSC2 chipset from SiRF was all about, and how it compares to the other SiRF chips such as the SiRFStarIII (also used in the very nice BC337 Compact Flash GPS receiver) and the SiRFXtrac (used in the SD501 SD GPS receiver), but there was nothing substantial to be found beyond “New SiRF GSC2 high performance and low power consumption chipset”, pulled directly from GlobalSat’s own web site. There was not even a reference to this chipset on SiRF’s own website! Now this could be related to the fact that the BT328 is new (and appears to be the only GPS sporting this new chipset), but it still seems strange. Since the GSC2 starts with “GS”, I can only imagine that it has been produced specifically for GlobalSat, and may be a re-labelling of one of SiRF’s existing SiRFII offerings. The specifications on the GlobalSat website show up a few subtle differences between this and the BT338 which could only really be put down to the different chipsets:
BT328 hot start time is 8 seconds (BT338 1 second). Warm and cold starts are the same.
Unlike the BT338, there are no claims of regarding sensitivity for urban canyon and foliage environments.
This unit does not claim to support WAAS or EGNOS
This unit can track 12 satellites as opposed to the BT338’s 20 channelsBut so what? Putting all that aside, the main question is “how does it perform in the field?”So, sitting next to each other on the window sill at my place, I thought I’d see how the BT328 and the higher spec BT338 reported our position. The BT-328 was reporting our position as 41°17.309′S, 174°46.343′E.The BT338 reported it as 41°17.290′S, 174°46.355′E.The BT-338 appeared to report our location a dozen meters or so closer to our true position using the available satellites.Who wants to go for a drive? - a side by side comparisonI next took both units for a short tiki-tour of my favourite city (Wellington), surrounds, and hills, each serving their position via Bluetooth to a Pocket PC running Memory-Map.In these screen shots, the new BT328 is shown as the red line, with the older BT338 as the green track beneath it.As a whole, I was impressed. The BT328 performed close on a par with the BT338 in most situations, including amongst steep hills and against cliff sides.The BT328 (red) tracking tightly like the BT338 (green) through steep hillside streets.The BT328 (red) kept a close fix heading around some high cliff areas.At times, the BT328 even seemed to out-perform its bigger brother by initially tracking fairly tightly heading into some urban canyon situations…The BT328 (red) tracking tightly, a tad better than the BT338However as I had thought may be the case, it would appear that the BT328 doesn’t generally handle the urban canyon challenges of tall buildings and narrow streets so well, as can be seen here.The BT328 (red) doesn’t handle the urban canyons though like the BT338 (green)I did notice however that when going through the Mt. Victoria Tunnel a couple of times, the BT328 seemed to retain it’s fix a fraction longer, and re-acquired it’s fix a second or so before the BT338. I assume this is because the BT338 does a bit more signal processing in its attempt to report a more accurate position. Chipset behaviour – for navigation or tracking?In my efforts to try to understand the properties of this new SiRF GSC2 chipset, I monitored as I was driving where the unit was reporting its position as I passed streets, and how it handled changes in direction. I did this to see if it performed like the SD501 with the SiRFII/XTrac chipset which is designed more for in-car navigations systems. If the GSC2 was the same or a related chipset, it would attempt to guess our position a distance ahead of our actual position based on our speed and direction (this to predict turns and directions in sufficient time when travelling at higher speeds). Some deem this behaviour a positive feature for navigation, but can often result in a false position tracking if that is your intention / requirement.From what I could see, this unit consistently reported our current actual position and made no attempt to second guess ahead, so this unit would really appear to be GlobalSat’s attempt to offer something similar to the BT338 but with a slightly cheaper price tag.The BT328 operating close on a par with the BT338, report accurate current location information.Not bad!Overall, this new entrant to Globalsat’s family is a very nice unit, and performs almost as well as the BT338, but at a lower price. It doesn’t seem to handle poor reception areas quite as well, but in most of my road testing, it held up well. If budget is not such an issue, the higher spec BT338 is probably a better option, however if you are looking for a good medium priced all-rounder / domestic GPS to go with your laptop or PDA, then the BT328 should serve you well for quite some time to come.Pros
Good tracking in most situations
Good battery life
Easy Bluetooth operation. Can connect to most Bluetooth devices
Lower cost than, but almost as good as the BT338
Small sizeCons
Like all Bluetooth receivers, needs to be charged separately
Not so good in urban canyon / tall building situations