I have an RS2 with an M2 for a base station and Lora wan connecting them, the base is about 100 feet from where I’m working, yesterday I took points using Field Genius from micro survey. Today I went back and the points were about 5 feet off north south and about 3 feet off east west. The base surveyed in and accumulated coordinates for 30 minutes. Tried re starting and re accumulating points on base and restarted the rover. Nothing except that it was about four feet off this time instead of five. I know These units can be Precise and people use them for grading and there are more expensive units that are even better, but I must be doing something wrong. Help!!!
If you were looking for repeatability you need to document the first averaged base position and then return it back to that point each time and manually enter the coordinate that was first generated. You can put the base on a point the was collected with RTK, but I will need to manually enter that coordinate.
What if I didn’t move the base station ? Could I leave it and just turn it off and come back the next day and turn it on? Or should I run a cord out to it and plug it in and leave it running?
You can switch on and off ,but in base mode you have to have it selected to manually enter the coordinates that were averaged that first day. then every time you restart it will have these coordinates
Ok I’ll try that, that explains a lot and that was a hunch I had but I’m used to ag gpswhere we set up the base on the farm when we got there and I remember leaving the tripod in the same spot until we were done that farm. Thanks for the help!
With this method, you will see the same point within milimeters from setup to setup. You will have 2-3 mm error from base setup to base setup, if you count in mechanical tolerances and so on, and otherwise do your due-diligence in the setup phase.
This is one of the reasons several of us have asked for a feature request of storing base data. Unless you are averaging using RTK fix from a CORS network, your base Lat/Lon and in particular Alt will be different day to day. It is averaging with no corrections.
For pass to pass you do not need the right “absolute” coordinates.
But you do need the exact same coordinates for that exact spot each time. Just as everyone has described.
Also make sure your base is immobile, if it sways in the wind the base movement will steer your tractor with it.
I have experienced no drift this summer using the M2’s, I cringe getting in a machine with auto steer running WAAS now.
in most of my applications, farm drainage either surface or subsurface drainage tile, the base is only relevant to that job. We do not survey them in. On a Trimble base we store the base data and name it, then a function called Autobase recognizes I am within feet of a known base point so it loads the LLH and becomes a transmitting base.
Repeatable accuracy is completely relevant to you your base station. If surveyed in, they should be good, if averaging with no corrections Lat/Lon can be of up to 10 feet. Altitude or height is much worse. I have seen a 30 foot difference from one day to the next. For my application, doing grade work to slope the ditch/field/tile this is terribly detrimental.
We use several methods of a semi permanent site. We made a pole, about 6 feet long, with a metal platform to mount the GPS receiver on. We then sink it in the ground 3 feet mount the base and do our survey/install work. When done we pull the mount. Another method we use is a telephone pole mount we made. We mount a bracket on a telephone pole in the field with clear view of the Southwest sky then mount our base. Another method I have seen is a bolt that is a lag bolt on the bottom with a 5/8ths bolt thread on top. We put a double nut on it then use a cordless impact driver to screw it into the top of an existing fence post.
Just some food for thought.
Haha, I just had a vision of a base on top of one of these…
Hahaha if it was mounted on the noodle man, the tractor would be in a wreck in no time! Too Funny