I am curious if anyone has done some study or trial to compare results between the use of VRS and Base / rover for topo locations. Understanding there are a lot of variables involved, I would be curious to hear what people's 'rules of thumb' for the use of either methodology, backed with some science or at least trial and error.
Thank you in advance!!
BC-Surveyor recently posted a video about this, take a look:
GNSS Corrections Compared - RTK vs RTN vs RTX & How to Build a Geodnet Base
Well there are lots of variables. Not all VRs networks are equal. NGS has done a study as well not for Topo but control. Now on Topo I prefer to set my starting control from our local network. Then establish control on site and off site via base rover robot etc least squares. Then Topo the relative accuracy is usually better from a base and rover setup. If the base has good open sky. This base and rover allows me to enter hostile environments more easily but I ramp up my epoch count and do other independent checks in areas. Network RTK is not used for hard surface location as I see in our area latency and poor cell coverage and I have no control over the network RTK providers servers and communication lines. Radio can be limited to range and terrain. But most of our sites we have little issue with this.
Speaking from experience “a.k.a. trial & error”; I have the most confidence in the Base-Rover scenario. I have previously used Utah’s TURN system and I am a current subscriber to Trimbles 'Center Point’ VRS System.
TURN is reliant on a cellular link, so it is limited in several areas I operate in. When I do have good reception, it works quite well and generally carries vertical in the +/- 0.03’ range. I have not experienced any noteworthy horizontal issues with it.
Trimble Center Point works everywhere as it is linked via satellite. I have not yet found an area where it does not function and yield good horizontal results, however not so much so for the vertical. I have experienced varying vertical accuracies on multiple days at revisited sites and I generally do not put any reliance in it’s vertical results. I can shoot the same point minutes or hours apart and I have seen vertical differences in the +/- 0.3’ range and on some occasions I’ve seen a couple of ‘wow’s. Also, I really have not personally found Center-Point to be any better than anything else I’ve used under canopy.
I am of course excluding electrical sub-station work from any of the above mentioned accuracies, and I once had a strange experience with TURN when operating near the Nevada Test Range. I'm pretty sure that issue was due to Aliens and not TURN. 😉
I frequently use a base for occasions where I need reliable vertical. I also frequently use a Robotic T.S., and a level as well, for foundations, and flat sloped curb & sewer.
Current equipment: Trimble R-10 Base - R12i Rover. Maybe my results might be better if my base was also an R12?
Just my 2 centavo’s.