Duration Track Test

The reliability of a GPS receiver can be tested using the tracking function. To do so, enable your device to create a continous track log based on time, like adding one measurement to the track recording every 4 seconds. Now place the device on a fixed spot and do not move it for one hour. The track recording you get shows the "Geodrift" of your individual device. The track can be visualized with services like www.gpsvisualizer.com.

Here are some examples, the first one was made by placing different GPS devices in the same spot, at the same time, for about 90min at an elevation of 104m, mostly free horizon. The position marked Pos is the spot as reported by a Trimble GeoXT (measured at the same time, with differential correction). All devices were switched on at the same time with track logging enabled.

Track recording of Garmin Venture HC 

Track recording of Garmin GPSMAP 60CSx

Track recording of Garmin Colorado 300 

Conclusion: All devices had the biggest inaccuracy directly after power-on, the first fix was the least reliable. This first fix inaccuracy was biggest and longest with the Colorado (>20m,60ft) and smallest with the Venture HC (<5m,15ft). Overall the Ventue HC showed the best performance actually being near the position all the time with most measurements being within 2 to 3m. Both the GPSMAP 60CSx and the Colorado 300 were minimum 3m(9ft) off all the time with peaks of 7 to 10m(30ft).   

The following test was made in the woods under more difficult receiving conditions. With trees on all sides a reliable referenvce measurement using a Trimbe GeoXT could not be made.

 
Track recording of Garmin Venture HC

Track recording of Garmin GPSMAP 60CSx

Track recording of Garmin Colorado 300

Conclusion: All devices had a greater deviation at the start of the recording, until they got a better fix. The Venture delivered the best results, with single measurmenets never being apart more than 10m and most measurements being within a radius of 5m(15ft). The GPSMAP 60CSx produced bigger variations in the position reported, exceeding a difference of 15m(45ft). Under the given conditions the Colorado was not able to report a stable position. Positions reported by the Colorado were up to 70m(200ft) apart.