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Appeared on: Wednesday, June 28, 2006
Polstar igeo-plus pbt-248

1. Introduction

Polstar iGeo-Plus PBT-248 - Page 1

- Introduction

Polstar Technologies is one of the few manufacturers that don't use the SiRF GPS chipsets in their devices. Instead, they incorporate Sony's 4th generation GPS chipset, the CXD2951GA-4, which promises high performance and good reception levels that match what SiRF has to offer. While doing this review, we will also be carrying out what should prove a rather interesting comparison between one of the best SiRF III enabled devices, the Globalsat BT-338, and the device under review, Polstar's i-GeoPlus PBT-248.

- Polstar iGeo-Plus PBT-248

The Polstar i-Geo PLUS is a high performance Bluetooth GPS receiver that is both compact and portable. The sleek and distinct i-Geo PLUS fits in your hand or pocket easily, allowing you to take it wherever you go. With the Polstar i-Geo PLUS, you can now add full GPS navigation capabilities to your PDA, smart phone or laptop at minimal cost while enjoying performance that rivals dedicated GPS navigators. Experienced and new users alike will be able to operate the i-Geo PLUS with minimal effort. By employing the Sony CXD2951GA-4 chipset, users will enjoy the fastest Time-To-First Fix and can begin navigation immediately.

Powered by Li-ion rechargeable batteries with an impressive battery life, the i-Geo PLUS is as easy to carry around as your mobile phone. Date transmission and connections via Bluetooth eliminate any need for wires, and the Bluetooth transmitter allows GPS data to be transmitted to your PDA, smart phone or any other Bluetooth enabled device within 10 meters. The high-sensitivity GPS receiver will pick up the weakest of signals, allowing you to place your i-Geo PLUS anywhere without compromise, and enabling you to begin navigation immediately with the very fast Time-To-First-Fix.

- Used chipset

The Sony chipset has the following specifications:

Sony CXD2951GA-4 WAAS enabled
1, 1575.42 MHz
C/A code:
1.023 MHz chip rate
12 channel all-in-view tracking

Acquisition: -139dBm
Tracking: -152dBm

Position Accuracy:
10 meters, 2D RMS 
~ 5 meters, 3D RMS WAAS
0.1 m/s
us synchronized to GPS time
WGS-84 Acquisition Time (Open sky, stationary)
0.1 sec., average
Hot start:
2 sec., average
Warm start:
35 sec., average
Cold start:
45 sec., average
18,000 meters (60,000 feet) max.
515 meters/second (1000 knots) max.
Less than 4g
Protocol messages:
NMEA-0183 output protocol, Bluetooth Interface Baud Rate 4800bps
Output format:
Operating temperature:
-20° to 60° C
5% to 95% Non-condensing

While the same in most details of the specifications, there are some minor differences between the Sony CXD2951GA-4 and the SiRF III:

  1. 12 satellites vs 20 satellites (SiRF III)
  2. Acquisition Sensitivity: -139 dBm vs -148 dBm
  3. Tracking Sensitivity: -152 dBm vs -159 dBm
  4. Hot/Warm/Cold start times of 2/35/45 vs 1/38/42 secs.
  5. The CXD2951GA-4 does not support the VTG output format

Something to look forward to in the results, is whether the sensitivity levels will play a major role in how good a receiver the Polestar device is compared to the Globalsat BT-338.

2. Package

Polstar iGeo-Plus PBT-248 - Page 2

- Package

For our testing purposes, Polstar Technologies sent us their retail package which includes:

The current price for the product is around US$70.00, as found around the net.

The i-GeoPlus GPS is about the same size as the Globalsat BT-338.

On the front, there are two LEDs as well as the i-Geo Plus logo. On the right hand side, there is the on/off switch and another LEF indicating the GPS device status.

On the left hand side, we have the DC input jack for charging the device.

Looking underneath, we find a label with certification approvals and some general information about the product:

The Li-Ion battery is rated at 1050mAh 3.7V:

The external dimensions are 74x43x21mm. The three LEDs, provide the following information:

3. Installation - Using the Device

Polstar iGeo-Plus PBT-248 - Page 2

- Installation

The installation of the device is very simple. After charging for about 3hours, you can then install it on either your PDA or BT enabled laptop. Remember, that pair key is four zeros (0000). All tests were carried out using an ASUS A6JA laptop. We recorded all data for a pre-selected route with VisualGPSX and later analyzed it with GPSLog.

In order to measure the TTFF ("Time to First Fix" which is the time it takes for a GPS to determine its current position), we used the GPSInfo "Cold Start" function. All tests ran simultaneously, under the same environmental conditions and all installed in an Audi model A4, 2004.

The retail package doesn't come with any kind of testing software. However, if you visit the Polstar Technologies website, you can download two pieces of software, one for PDAs and one for PC platforms.

- Tests Day One

On the first day, we tested the device under a clear daylight sky, with 28°C. There are no TTFF times, since there isn't a utility available to perform this measurement for Sony chipsets.

Globalsat BT-338
Polstar i-GeoPlus PBT-248


Average (in view)
Average (in use)
Average Signal Level (in dB)
Maximum per Satellite
Average per Satellite

The Polstar PBT-248 showed good performance. It had on average about one satellite more in view but the same in use than the BT-338. The average signal levels were also much higher than the BT-338, reaching up to 47 dB.

- Tests Day Two

On the second day, we tested the device with a partly-cloudy daylight sky, 30°C. Again, there are no TTFF times.

Globalsat BT-338
Polstar i-GeoPlus


Average (in view)
Average (in use)
Average Signal Level (in dB)
Maximum per Satellite
Average per Satellite

Again good performance, although the Polstar device's average in use satellites count is much lower than the BT-338, despite having a higher in view satellites count. High average signal levels once more form the i-GeoPlus.

- Tests Day Three ( Indoor Sensitivity)

We placed both receivers inside a house, close to a large window and monitored their performance. The Polstar PBT-248 had a problem getting 3D fix, whereas the Globalsat Globalsat BT-338 had a 3D fix with 7 in view and 5 in use satellites.

- Overall impressions

The Polstar i-Geo Plus PBT-248, powered by Sony's 4th generation chipset, showed very good performance compared to the SiRF III chipset. The device didn't have any problems, obtaining a quick 3D fix quickly with good reception levels, reaching up to 47dB (max). It also seems to be being able to view more satellites but doesn't use more than the BT-338. The only weak area was in our indoor tests, but then you wouldn't be using a device like this indoors.

4. Summary

Polstar iGeo-Plus PBT-248- Page 3

- Conclusion

Polstar Technologies is been one of the few companies to use Sony's GPS chipsets in designing their quality products. Polstar promises great reception levels, and it seems that Sony's 4th generation chipset is able to deliver it. In most of our tests, the performance was equal to or better than Globalsat's BT-338 which was good to see. After all, the more good products, the better it is for all users. The device doesn't have any obvious weakness, although the ability to connect an external antenna may be handy.

The low retail price of US$70.00 makes it quite interesting option, as opposed to SiRF III devices, like the Globalsat BT-338. Hopefully, the GPS community will provide more utilities for Sony enabled GPS devices, offering more advanced features.

The Positive

The Negative

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