Garmin GPS10 with Bluetooth
for use with
HGIS® GPS Mapping Applications

Field Test Report

Date: April 1, 2007

 Copyright 2007 StarPal Inc

All Rights Reserved

Garmin GPS10




StarPal has tested the GARMIN GPS10 with Bluetooth using Windows Mobile (Versions 4.2 and 5.1).  This is a useable GPS for many applications. There are some quirky things about this GPS. We will tell you these in this report.

GARMIN SPECIFICATIONS:
Battery: Up to 12 hours (typical use); rechargeable lithium-ion battery - Good battery life per charge (battery is not user replaceable) Expect the internal battery to last about 3 years (then you must run on external power, or return unit to factory)
Waterproof — so it can be mounted outside the car for a clear view of the sky - Nice, but not claimed to be waterproof when running on external power.
Integrated, wireless GPS receiver and transceiver with Bluetooth technology —  up to 30 feet - We recommend keeping the units in view of each other and within 12 feet  (otherwise GPS may freeze up or power down)
WAAS enabled, 12 parallel channel GPS receiver continuously tracks and uses up to 12 satellites to compute and update your position - Tracks 12 satellites, but only uses 9 satellites in position calculation (our proof is shown in our graph below)
Unit dimensions: 1.77 "W x 3.46 "H x .75 "D Weight: 2.8 ounces -  Small size, Light weight
Magnetic and hook-and-loop fastener mounts  - This is nice, you can mount it on your hat for a full view of the sky (It needs a full view of the sky)
Waterproof: IEC 60529 IPX7 standards (submersible in one meter of water for up to 30 mins.) - Not claimed to be waterproof when running on external power.
DGPS (WAAS) accuracy: Position: < 3 meters, 95% typical - Yes, but with conditions: Good Weather, Full View of the sky, tracking at least 9 satellites.

Bluetooth Problems
Bluetooth has more problems when using Windows Mobile 4.2 (also called CE.net, and Windows CE version 4.2) while connecting, compared to Windows Mobile 5.1.  After the Bluetooth link connection is made, and the two units stay in range (12-15 feet), the GPS10 only froze once during approximately 350 hours of testing. We experienced problems with plug-in Bluetooth cards freezing the Windows Mobile 4.2 computer while making the link connection..  To minimize problems, we recommend using handheld computers with Windows Mobile 5.1 or greater with Bluetooth hardware built-in.

GPS10 Documentation clarification about using external power
The GPS10 manual states that "Anytime that the link between your mobile device and the GPS10 has been broken for fifteen minutes, the GPS10 will turn OFF to conserve power.  If you are using switched external power to operate the GPS10, the GPS10 automatically powers ON whenever the switch is activated."   The GPS10 will actually shut down after 15 minutes on external power if the Bluetooth link connection has never been made and never broken; an unexpected behaviour for the GPS10 if you takes its documentation literally. Therefore, when running on external power, you must turn ON the external power only within 15 minutes of the moment you plan to use the GPS10.  You cannot use unswitched external power with the GPS10 mounted in a remote location where its internal power switch is inaccessible.  This is a disadvantage of this unit. Lets say you start your vehicle which powers up the GPS10, drive to the field you are going to map; now the GPS10 has already shut down and you have to turn off your vehicle and restart it to get the GPS10 started again.  After that, the GPS10 can take another 45 seconds to generate a valid fix.  Rather than use the vehicle ignition switch to cycle power to the GPS10, add another power switch in-line with the GPS10 power cable to reactivate the GPS10 when needed. This switch is also used when interference breaks the link connection, or the units go out of range of each other. Other GPS receivers we have tested do not have this shut-down problem.

GPS TESTING
We tested the GPS10 under different weather conditions from clear sky to cold fronts and snowy conditions. As expected, this GPS is less accurate when the weather gets worse. Surprisingly, more satellites being tracked does not make the GPS10 more accurate (most GPS receivers will improve accuracy as number of satellites increase). The GPS10 only uses the "best 9" satellites even when it reports up to 12 are being tracked. The other 3 satellites are ready spares in case one of the "best 9" satellites drops out.  Operating in this way may extend battery life although it provides less accuracy (we were testing it on external power so battery life is not an issue). The GPS tracked 9 to 11 satellites for over 90% of our test; fewer data samples were collected at each end of our graph. Therefore, some variability is seen at both ends of the following graph (at 8 and 12 satellites). The most interesting part of the graph are the flat lines from 9-11 satellites under each of the weather conditions.  This indicates that the GPS is only using 9 satellites in its calculation.

RESULTS
With a Clear Blue Sky and the GPS10 has a Full View of the Sky and the GPS10 is tracking 9 or more satellites, you should expect to be within 2.4 meters 95% of the time. We define a full view of the sky as being able to see within 15 degrees of the horizon essentially all the way around.  Garmin specifies "3.0 meters 95% of the time typical" (we would add to this statement: a clear blue sky, full view of the sky, and tracking 9 or more satellites). A good view of the sky and good weather is important for this GPS. Sometimes, there are 8 or less satellites available (this occurred about 5% of our 340 hour test).  During these periods, the GPS10 may not be within 3 meters.

 Weather

CONCLUSION
Walk-About - The GPS10 works best mounted on a hat for "walk-about" mapping in open areas. If you are walking around an open area and want accuracy to be within about 10 feet, the GPS10 is an excellent choice. The GPS10 will work best in locations where it can track at least 9 satellites or more.  The GPS10 will not be as accurate under tree canopy as GPS receivers that use 10-12 satellites to calculate position. Running on external power has the aforementioned problems of automatically shutting down, and concerns about watertight integrity.

On-Vehicle - The GPS10 may or may not be the best choice.  The GPS10 only updates once per second, which makes it harder to navigate a vehicle. The GPS10 only uses 9 satellites in the fix calculation which makes it a little less accurate.  The GPS10 auto-shutdown "feature" can be annoying. If you are running an iPaq with Windows Mobile 5.1 or later, the GPS10 Bluetooth may have fewer problems than the iPaq Serial Cables (which have had significant reliability problems).  If you have a computer with a real DB9 Serial Port (like the TDS Recon or Juniper Systems Archer), then a GPS like the Garmin GPS18-5Hz would be preferable to the GPS10.

We hope this report helps you in your GPS Decisions.
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