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Appeared on: Monday, April 03, 2006
F-Tech Solar 7

1. Introduction

Apart from the usual array of battery powered GPS devices, F-Tech recently presented a Solar powered SiRF III based BT GPS device that not only promises good performance, but also doesn't require you to charge it, assuming of course the weather is sunny! We compared the device with the best known SiRF III GPS from Globalsat. The results should be interesting. First, let's get some background information on F-Tech.

- F-tech background

f-tech Corporation is a professional SAW (Surface Acoustic Wave) device-designing and manufacturing company. f-tech was founded in November 2000 and located in Tainan Science-based Industrial Park. f-tech's aim is to become a leading company in the design and manufacture of SAW devices and RF modules in Taiwan. f-tech products include IF/RF SAW filters, SAW resonators and SAW sensors. They are widely used in Wireless LAN, Mobile Phone, Cordless Phone, Tuner, GPS, Security System, Remote Controller, Tyre Pressure Monitoring Sensor (TPMS) and Biological & Chemical Sensor.

As F-Tech comments: "...We offer an excellent designing ability, high-quality processing technologies and premium service to cooperate with our customers to develop new products. By providing complete "custom-designed" service, our products can meet the requirements of technical specifications, shortening designing cycle and time-to-market. Our mission is to be the best partner with our customers..."

- F-Tech Solar 7

The Solar 7 Bluetooth GPS Receiver is a complete GPS receiver solution. High capacity rechargeable lithium-ion battery with solar charging circuit built-in, GPS antenna and Blue tooth transmit/receive system are all included. It is designed on the most advantage GPS kernel (FirstGPSTM), full-function, industry-level locating capacity and low price.

You can use the Solar Bluetooth GPS Receiver as a vehicle navigator, for security systems, geographic measurement, investigations or for agriculture purpose. The Solar Bluetooth GPS Receiver can communicate with other electronic devices via its Blue tooth interface. The built-In Flash Memory can save satellite information and do an almanac refresh periodically. This will shorten Time To First Fix (TTFF) dramatically.

Patent protected Solar Cell design can extend the device usage time by up to 15 hrs. This is much longer than what the competition offers. The Lithium-ion battery can be re-charged under natural or artificial light, regardless of whether the Solar 7 receiver is turned on or off. Very rarely, do you have to concern yourself with charging!

- Used chipset

The SiRF III chipset has the following specifications:

Chipset: SiRF Star III WAAS enabled
Frequency: 1, 1575.42 MHz
C/A code: 1.023 MHz chip rate
Channels: 20 channel all-in-view tracking
Position Accuracy: 10 meters, 2D RMS 
~ 5 meters, 3D RMS WAAS
Velocity: 0.1 m/s
Time: us synchronized to GPS time
Default: WGS-84 Acquisition Time (Open sky, stationary)
Reacquisition: 0.1 sec., average
Hot start: 1 sec., average
Warm start: 38 sec., average
Cold start: 42 sec., average
Altitude: 18,000 meters (60,000 feet) max.
Velocity: 515 meters/second (1000 knots) max.
Acceleration: Less than 4g
Jerk: 20 m/sec
Protocol messages: NMEA-0183 output protocol
Output format: GGA(1sec), GSA(5sec), GSV(5sec), RMC(1sec),VTG(1sec)
Operating temperature: -20° to 60° C
Humidity: 5% to 95% Non-condensing

Looking at the SiRF III specs, we notice that the chipset is capable of receiving up to 20 satellites (actually 12 maximum), it has very low Hot/Warm/Cold start times and its accuracy reaches ~5m when WAAS mode is enabled.

2. A Closer Look

- Features

  1. Total solution in power management. Unique Solar Cell re-charging design (patent protected) can extend your GPS operation by up to 15 hrs.
  2. Green environmental protection in a wireless GPS receiver application
  3. WARM/HOT start with built-in battery
  4. Well though out LED/switch button design
  5. Automatically updates almanac/ephemeris in flash memory
  6. 20 Channels "All-In-View" Tracking
  7. Position accuracy of 10 meters 2D RMS
  8. Cold/Warm/Hot Start Time: 42/38/1 Seconds (Signal Strength > 30 dB-HZ)
  9. Reacquisition Time: 0.1 seconds
  10. Support Standard NMEA-0183 at 38400 bps baud rate (Defined by customer 4800 up to 57600)
  11. Support Power Saving Mode
  12. Compatible with Bluetooth devices with Serial Port Profile (SPP)

For our testing purposes, F-Tech sent us the retail package that includes:

The current price for the product is around US$100, around the net.

The F-Tech Solar 7 GPS receiver is the largest device of its type that we have reviewed. We would say its almost twice the size of the BT-338.

Comparing it with a Sony Ericsson K750i, it still looks big.

while a credit card looks much smaller :-)

Looking at the bottom, we can find some information about the product, like its S/N and the exact model identification (FGPSBT02)

The battery is rated 1000mAh 3.7V

There are two LEDs, indicating the following conditions:

On the top, we find the charger interface (mini USB), the power on/off switch and the two leds. On the left side, we have the external cable jack (MMCX compatible). Both inputs are protected by a rubber cover.

The package, as we saw earlier includes two chargers, one for AC/DC and one for car. Since the device is USB compatible, it can also be powered by a PC USB port!

3. Installation

From our tests, to fully charge the device requires around 3 hours. It then takes a few simple steps on your PDA device to connect, in our case a Dell Axim x50V with Windows Mobile 2003 SE. Start by accessing the bluetooth manager and tap New->Connect

The F-Tech Solar 7 will show up with the ID "BT GPS":

Press Next->Select GPS OUTPUT-> Next


After accessing the BT Manager, right click on the BT GPS, select connect and that should be it.

Finally, our device was connected to the Dell Axim x50V PDA and ready to use! There are several details available about the activity of the BT port.

The device can be found at COM7 with 9600 communications speed. Press "Scan GPS" and if all goes well, you will see streams of numbers scrolling by.

Unfortunately, we couldn't check the device's firmware, since none of our software could switch to SiRF mode and perform/set all advanced functions.

4. The Tests

- Tests Day One

We tested the device with a Dell Axim X50v. We recorded all data for a pre-selected route with VisualGPSce (free edition) and later analyzed it with GPSLog. In order to measure the TTFF tests ("Time to First Fix" which is the time it takes for a GPS to determine its current position), we used GPSInfo "Cold Start" function. All tests ran continuously, under the same environmental conditions (night, clear sky, 2.5° C ) and all installed in an Audi, model A4 2004.

Globalsat BT-338 F-Tech Solar 7
Time to First Fix (TTFF) Secs 38 sec 45.25 sec
Fix Invalid 0 0
2D 0 0


100 100
Satellites Average (in view) 8 9
Average (in use) 5.19 4.94
Average Signal Level (in dB) Maximum per Satellite 47.33 46.20
Average per Satellite 38.43 36.87

The F-Tech Solar 7 showed typical behaviour for a SiRF III powered GPS receivers. Quick TTFF times and good reception strength. Unfortunately, the device cannot reach the BT-338, not only in size but also in performance.

- Tests Day Two (Pedestrian use)

We tested the device with a Dell Axim X50v. We recorded all data for a pre-selected route with VisualGPSce (free edition) and later analyzed it with GPSLog. All tests ran continuously, under the same environmental conditions (day time, clear sky, 20° C ) carried along with us. For this test we enabled the "Static Navigation" on the GlobalSat BT-338.

  Globalsat BT-338 F-Tech Solar 7
Fix Invalid 0 0
2D 0 0


100 100
Satellites Average (in view) 8 8
Average (in use) 5 4.94
Average Signal Level (in dB) Maximum per Satellite 45.00 43.00
Average per Satellite 35.73 34.45
Speed (km/h) Minimum 1.06 1.58
Maximum 6.23 7.01

Despite the fact that the F-Tech Solar 7 is a SiRF III based unit, all used software couldn't switch to SiRF mode and hence we couldn't set static navigation on. Which can be considered as a disadvantage, compared with other SiRF III devices.

- Tests Day Three (External Antenna)

We tested the device with a Dell Axim X50v. We recorded all data for a pre-selected route with VisualGPSce (free edition) and later analyzed it with GPSLog. All tests ran continuously, under the same environmental conditions (night, clear sky, 2.5° C ) and all installed in an Audi, model A4 2004. This time, we had installed an external antenna to the device to see if it would make any difference, compared with the standard, without external antenna version.

  F-Tech Solar 7 F-Tech Solar 7 + antenna
Fix Invalid 0 0
2D 0 0


100 100
Satellites Average (in view) 9 9
Average (in use) 4.94 4.83
Average Signal Level (in dB) Maximum per Satellite 46.20 49.40
Average per Satellite 36.87 39.19

The external antenna improved the receive signal (max/average) levels, but didn't seem to improve the average in use satellites.

- Tests Day Four (Indoor Sensitivity)

We placed both receivers inside a house, close to a big window and monitored their performance. The F-Tech Solar 7 had a 3D fix, having in view 8 and in use 4 satellites, where as the Globalsat BT-338 also had 3D fix with 7 in view and 5 in use satellites.

- Overall impressions

The F-Test Solar 7 device showed typical SiRF III performance, without reaching Globalsat's BT-338 performance. The external antenna will improve the overall reception levels. What troubled us is the fact that the device cannot switch to SiRF mode, which offers many advanced options and features to the user. While this probably won't worry average users, it should be something to note.

5. Conclusion

F-Tech's Solar 7 GPS device is unique, since it combines the strengths of the SiRF III chipset with a solar charger circuit built-in. According to F-Tech's website, there are two versions, one with SiRF III (tested) and one with Xemics (not tested). The Xemics version with power from a Solar panel, allows for up to 30 hours working, while the SiRF III manages up to 15 hours (+3hours). While we expected more power juice from a solar panel, we are not complaining about the extra working time. While it's not exactly clear, the device is battery based with power assistance from the solar panel.

Despite the fact that the Solar 7 is reputed for its solar panel, F-Tech suggests that:

"....Since the Solar Bluetooth GPS Receiver got high performance rechargeable lithium-ion battery, we are strongly recommend you not to place it under the sunshine for a long time..."

That means, if you put your Solar 7 on the dashboard under a hot, searing sun for a long time, it may fail. The fact that it is black doesn't help although it also comes in silver which may be more suitable, especially for locations with intense sun. Of course, the device can also be powered with artificial light, which sounds safer.

On the bright side, the embedded SiRF III shows its strength providing very good reception strength, as was expected, while the use of an external antenna will further improve reception.What may annoy power users, is the fact that the device cannot switch to SiRF mode and therefore doesn't offer numerous advanced features. The price for the Solar 7 is around US$100 which is cheaper than Globalsat's BT-338.

The Positive

The Negative

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