Hello all, I work for an environmental firm and we are looking for a product to record and find GPS locations of water sampling wells and soil sample locations, ect… These products and Sparkfun seem to be what we are looking for and I think i’m on the right track. We have been using google maps and .kmz overlaps on an iphone but its just not accurate enough. Most of the apps on the iphone are not accurate either. I also tried a Garmin GPSMAP 66s and I can’t get it any closer than about 10-20 feet. Could you help me with a couple affordable options? The RTK surveying kits look like they might do the job but most of the information is a bit over my head as I know very little about surveying. Also there may be a cheaper simpler version that will do the job? Thank you, Russell
How accurate do they need to be? Start here https://www.sparkfun.com/GPS_Guide and find unit that matches what you’re after, then on that product’s page click ‘documents’ for useful links…the most useful one is usually the hookup guide. They have links to other relevant guides and such, and walk you through each step (you can familiarize yourself before it comes, then be ready to go!)
I also tried a Garmin GPSMAP 66s and I can’t get it any closer than about 10-20 feet.
If you are outdoors, with a clear view of the sky, you should be able to do much better than that, with any modern GPS module.
A common mistake made by beginners is to forget to set the GPS unit to the “map datum” or “coordinate reference system” assumed by the person who made the map, or recorded the locations. There are DOZENS of them, and failure to translate GPS coordinates from one map or database coordinate system to the other can lead to a variety of errors, some quite large.
Here is one introduction. https://www.esri.com/arcgis-blog/produc … ifference/
There are various on line calculators and software packages that do the interconversions for you. One example: https://www.ngs.noaa.gov/NCAT/
Finally, go into the System setting of your Garmin GPSmap 66s and tell us which map datum you have selected. WGS84 is popular and used by Google Maps, but for example, government agencies in the U.S. often use NAD27, and you may have a hard time discovering that. Discrepancies of 50 to 100 feet may result if you make the wrong choice.
I have a much older GPSMap 60 and I’m getting less than 1 meter accuracy. Try turning on WAAS and see if that helps.
Thank you all for your responses and info. I will look into the links you gave me. If I understand correctly this sparkfun is a way to “build” to my needs? As far as distance it would be great to be within inches but truly within 2 feet or so would work. I will also tinker around with the settings on the Garmin (that was good info) to see how that works. I really thought it was going to be easy to just get a device to match my needs but the more I look into this I realize how complex it can be. I am really just looking for simple way to mark a GPS location and be able to find it at a later date even with terrain changes (overgrown, grass, covered in sand, ect.) and thought an app on my iphone would do it. Thanks again! I will get back on how things go.
I am really just looking for simple way to mark a GPS location and be able to find it at a later date even with terrain changes (overgrown, grass, covered in sand, ect.)
Your Garmin GPSmap unit is a fine choice, and really all you need. Set the unit to WGS84 to be compatible with Google Maps, if that matters to you.
It can be difficult to find out what smart phones do with GPS.