GPS Accuracy |
GPS Accuracy - On It or Close Enough? Some people do have concerns over the accuracy of a hand-held GPS units. With WAAS enable GPS units, accuracy can be down to 7 feet, so it says. GPS units which also support averaging (or pinning) seem to make better measurements. GPS units that support an external antenna make the best measurements when the external antenna is used. It all depends on what you are using the GPS to locate, a large structure like a house, a tree, or an underground items like a shut-off valve.
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GPS Accuracy - Test Using a Microsoft USB and Garmin eTrex Handheld Measurements were made for one hour with the two units side by side. The orange dots are from the Microsoft USB GPS receiver and the green lines are from the Garmin eTrex. Both were connected to similar computer via USB ports running the same program acquiring data via standard NMEA messages. The Microsoft USB GPS had a spread of about 90 feet while the Garmin eTrex some 7 feet. The X_PD point was located using Google Earth and varied based on the image being used. The Garmin eTrex drifted between 7 to 12 feet from the point defined using Google Earth. |