Somebody knows a good DGPS Reciever for computers (should have accuracy of at least 10 meters). would help a lot for mapping...
OpenStreetMap
Somebody knows a good DGPS Reciever for computers (should have accuracy of at least 10 meters). would help a lot for mapping...
Discussion
Comment from tbrooks on 26 January 2010 at 05:50
Unless you're using a mapping grade receiver (if your GPS cost more than $500, it might be mapping grade - it should have clearly stated such), the best you're reliably going to get is 10-m with an out-of-the-box device. One can dial down to a few meters, but that it most typically IF your device is WAAS (wide area augmentation signal -http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System) capable and you're relatively near one of the US Coast Guard beacons broadcasting that signal. We've found that if we purchase something like Microsoft Streets and Trips (about $129), it comes with a USB GPS. We've had success throwing away the software and just using the GPS with ESRI's ArcGIS. The GPS toolbar in the latter allows you to monitor HDOP and PDOP so you could potentially post-process your data using an application like OPUS (free - see National Geodetic Survey - (http://www.ngs.noaa.gov/OPUS/) but this can be tricky stuff. Another trick is to try to calibrate your GPS before you start mapping and every hour or so until you finish by "occupying" a known point - something like a NGS marker for which there are known, published coordinates - this will help you dial things in a bit (keep in mind that things like urban canyons and number of satellites will need to be monitored as they will alter accuracy and precision as you measure). I hope this helps!