To the average consumer, a soothing voice offering most-of-the-time-correct driving instructions to a good restaurant in an unfamiliar town is all that is required for total GPS satisfaction.“In one-hundred feet, turn right.”Thanks, talking car! However, the fact that you are reading this on Juniper Systems’ blog for data collection experts says that you are likely a professional trying to squeeze every last drop of precision out of your GPS receiver for accurately marking, tracking, and navigating back to assets or samplings.
What follows is a list of some basic best practices to improve GPS accuracy, applicable whether you are using a rugged handheld computer with navigation-grade internal GPS, or a more sophisticated precision receiver. As always, if you don’t find what you are looking for here, or are experiencing any difficulty while collecting data,contact a RJM Precision Instruments expertfor some helpful free advice.
Common GPS Problems and Solutions:
Problem #1: Obstructions
Because the GPS signal coming from the satellites is very faint, there are several objects that can prevent the direct line of GPS signals from reaching the GPS receiver, whether they are overhead or adjacent obstructions. These objects include mountains or other terrain, tree canopy, buildings, and your own body.
Solutions
Problem #2: Multipath or Signal Reflection
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Multipath errors or signal reflection occur when the GPS signal reflects off of buildings or other objects, resultingin multiple delayed signals. Since the GPS system worksoff of time, anything that causes delays can result inerrors in position. The GPS receiver picks up the directGPS signal and detects the reflected signals, thereforedisrupting the accurate data already collected by thehandheld. If you are near a building and your GPS isshowing 12 of 12 satellites are visible, yet your GPSposition is bouncing around on the screen, it is verypossible that some multipath errors are occurring inwhich some satellites are being counted twice by theGPS receiver.
Solutions
Problem #3: Map Error
When using GPS with a handheld computer, you have several options of background imagery or aerial photography to use as your base map. Often times, the base map will not be referenced to the same datum or projection as the GPS receiver, resulting in discrepancies between the object’s actual GPS coordinates and where it is mapped on the base map displayed on the handheld. For example, the GPS receiver data may be reported in WGS84 datum, while the aerial photography is reported in a different projection, such as NAD83. This results in a mismatch of data that can reach up to 4–6 feet or more.
Another reason for map error is simply because the map was created in the past and is now outdated. Items such as roads and buildings may not have existed when the map was created. Changes in elevation, photography angles, and the curvature of the earth may also affect the accuracy of the imagery.
Solutions
General Suggestions for Better GPS Accuracy
If you are already following the tips above, but still require a greater level of GPS accuracy, we can help you find the equipment and knowledge to do it. Please give us a call at 253-922-8808 or send us an email Info@RJMPrecision.com
What ways have you found to improve GPS accuracy? Share with us in the comments below.