Base Rover Newbie

I am not an expert, so feel free to ignore ....

If all that matters is relative positioning in your project, then you could just use a quick position on the base and forget about any VRS.

If accurate absolute coordinates are needed, then getting a position from VRS on a rover point might supply that. Is that going to be accurate enough?

If you later get a better position on the base (maybe submit base to OPUS) can you correct the rover measurements?

You could do it the way you propose, and if you needed NSRS correct coordinates on your first site visit it would be a good way. But my preferred work flow (for the first visit to a site) is this:

1. Setup the base over a random point.?ÿ

2. Set the base to collect raw data for OPUS as it sits.

3. Establish an autonomous position for the base, and proceed to RTK.

4. At the end of the day download the satellite data and submit to OPUS.

5. Shift the (Autonomous based) coordinates you collected onto the true (OPUS) base position. The shift should be on the order of 5-10 feet.?ÿ You could do that in CAD or in Excel, I like to use StarNet to recalc the coordinates from the vectors with the corrected base position held.

Now you have a correct (or as near correct as OPUS can make it) position for your base station. On subsequent visits to the same site you can just set up over the same point and specify the base position.?ÿ ?ÿBut you can still collect OPUS data again and average the results of the 2 sessions. Or just take solace in the assurance that the first was good.?ÿ?ÿ

?ÿAs for security -?ÿ in every instance of bases getting stolen that I know of the base was set up right beside the road. As in on the shoulder. Get it 20 feet off the road and your chances of having it taken go way down. Get it on the other side of the right of way fence and you are nearly golden. Church yards on weekdays and schoolyards in summer (in non-COVID times) are my preferred locations. Infields of highway interchanges are often suitable. It doesn't have to be right in the middle of your work area, just within radio range.?ÿ

Step.3- I usually take the ƒ??goodƒ? RTK coordinates derived from CORS solution. Move the base to this point, then choose set base over known point. If I have an external battery or not doing a job over 45minutes-1 hour I always collect raw. since you are using SurvCe and if you are using Carlson Survey. Process the raw vectors thru Survnet. A 30 minute phone conversation with a Carlson rep and I could calculate my Relative Position values from the ƒ??goodƒ? base control point to any point I stored. Carlson is good stuff!

Actually for Step 3, I have the unit that will be the base also setup as my network rover. After I have a ƒ??goodƒ? SPC coordinate from hooking to the states VRS. I make the same unit my base, no reason to pick it back up after it is set.?ÿ

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I have been using a Leica set for the past couple years, but this is the way I have my base/rover pair setup.?ÿ

My base/rover work flow is pretty similar to what Norman Oklahoma described. I'll scout the area looking for a good open spot within easy radio range of the work, preferably higher in elevation to get better range and fire up the base using an autonomous point. I'll code this first autonomous position as Point #"_HERE" and carry on with collecting shots or setting out some points for the gun. After a few days I'll convert the base raw data to a Rinex format and submit it to OPUS and key those coordinates into the job as Point#_OPUS and translate everything done off the autonomous position to the OPUS position, generally not more than 5-10'. If I have OPUS based control already within radio range, I may localize on it to get going, but nearly always follow up with an OPUS solution as a check. As far as security goes, it depends on how bad the neighborhood is. I can usually put my base up in a location that would require someone to go to some effort to get to it and not pull right up and toss it in their trunk. I'm partial to fire station parking lots or anywhere there's a CC camera around (in a perfect world). I do nearly everything in SP these days. All the control gets wiped I can OPUS in and match up with old work within a couple centimeters. Virtual control using CORS (via OPUS) is the way to go and you need a couple hours of good base data to pull that off. Avoid using local projections unless there's a good reason. Can always postprocess those into a standard projection later.

Norman OK's workflow is what I follow usually.

One suggestion - initially do some double checking as to how well the OPUS solution matches with the network solution to verify all your settings are matching up in the network/GNSS unit/collector chain.?ÿ The first few jobs, I might go with getting the initial start point with the network unit - start base with this known point - collect data for OPUS - in office compare network and OPUS.?ÿ Once comfortable that there are no significant differences, I would be more comfortable with holding the OPUS.?ÿ It would suck if there was a difference and you ran out to a job for a "quick" pick-up and used the network for ease and it was just enough different to matter.

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Base safety - contact neighbors to let them know you are doing a survey in their area and ask the one with the most open (sky view) and hidden (from shifty eyes) location if you can set up on their property.?ÿ When in doubt of equipment safety, get an extra person to just babysit the gear.

Posted by: @jon-payne

contact neighbors to let them know you are doing a survey in their area and ask the one with the most open (sky view) and hidden (from shifty eyes) location if you can set up on their property.

And he says, "sure, but while you're here could you do me a favor and find the corner pin that I know is over there somewhere?"

One some the tunnel jobs I have ran, I would process and send for an OPUS solution to check my starting and ending control. I would think that that the project specifications would dictate whether this was needed. If I running base/rover for your everyday boundary survey then I donƒ??t see the benefit in an OPUS position???ú??¯ƒ?ƒ??‹?. I am more concerned with the vectors in the raw file. If I am doing preconstruction design surveying or setting initial project control points then yeah I would run thru OPUS.

@bill93?ÿ That might happen Bill.?ÿ An easy answer might be adding a look for that as a means of helping resolve the boundary you are working on anyway.

Just a brief think back in time and I don't recall any time I've had that request in my area.?ÿ That happens frequently when I'm working with the total station even if I'm not on their property LOL.

@eastkysurveyor?ÿ One of the benefits to the OPUS solution on the everyday boundary survey is that you are tied to a known control network with every property instead of using the variable +/-10' here position to start.?ÿ While it might not make a difference in the isolated case of one boundary survey.?ÿ It is really handy when you start filling in the pieces in a neighborhood over time to have everything tied to that known system.

@jon-payne No doubt, but that would more than likely be in an area of little to no cell coverage-right?

My Base/Rover technique varies depending on the scope, size and time frame of the project.?ÿ If the job is short term and only requires one base I will use a method similar to Mark's.?ÿ I set up the base at a random location that has good satellite views but bad road views.?ÿ I'm not overly worried about radio suitability for the base since it has a built in UHF radio that I can transmit my repeater if needed.?ÿ I also tend to use a cellular IP connection when possible.?ÿ Fire up the base and broadcast based on an autonomous position while collecting raw data.?ÿ Unlike Mark, I use the autonomous base value for the duration of the project.?ÿ This limits a bit of possible confusion.?ÿ When the project is complete I either post process the base data against adjacent CORS or send it off to OPUS. Then I translate the RTK derived coordinates to the final base value.?ÿ In my case this is done in the manufacture's processing software.

If the project is long term or covers a larger area requiring several bases, I prefer to develop a static network before I begin RTK operations.?ÿ It takes more time but I budget for that in my proposal.

Posted by: @john-putnam

I also tend to use a cellular IP connection when possible.

Interesting. ?ÿCellular connection between your local base and rover?

@eastkysurveyor?ÿ OPUS is absolutely great in the case of limited/no cell coverage.?ÿ I still like it as a double check when in an area with network options.?ÿ Never hurts to have an extra check and the unit is doing all the work while I am doing other things.

Although the network solutions I've looked at are very good, I still hesitate to hold them as "the" position over an OPUS solution that comes back with really good statistics.?ÿ I think that goes back to running a test someone on the board suggested years and years ago of just automatically collecting RTK points at a time interval over the day and comparing them with each other.?ÿ There was a much bigger range than the specs might lead one to expect if you weren't thinking in terms of to what standard deviation manufacturer ?ñ values are being reported in.

Quick look at specs on a modern GPS unit seems to still show static at about half the expected error of RTK.?ÿ?ÿ Though both are fairly low numbers when thinking of other sources of error.

@brad-ott

Yes, some projects require a tighter solution than you get with a real-time network.?ÿ For those situations I prefer to use the IP connection over my UHF when in a cellular rich environment.?ÿ I don't have to worry anyone stepping on my signal.?ÿ The base has a static IP address which it broadcasts corrections over.?ÿ Similar to NTRIP but without the middle man.?ÿ In fact it might actually be an NTRIP server on the base.

@jon-payne

Not to knock OPUS, but unless you are using OPUS Projects or adjusting the extended output data inhouse, your results are just an average of the three (3) vectors for any given submission.?ÿ Great if you are working from a single point, not so great if you start bring than one set of results into the solution.

@eastkysurveyor

bingo - this is what I do. The receiver is sitting on a tripod all nice and level and over the point. I take a 3-minute VRS shot with that receiver set up as a network rover, then set it up as a base using the VRS position. Also, while I am broadcasting corrections I also collect static to be processed later and used as a check on the initial VRS obtained base position. But this is for SPC surveying only.?ÿ

I like to examine and edit my data while my memories are still fresh. So I download and edit immediately after returning from the field.?ÿ To prevent possible overwrites of my edits, I have a new data file for each day, rather than continuing with the previous day's file.?ÿ

In spite of what I might have seemed to write in my first posting, I might go some days with the autonomous base position.?ÿ But by the time I'm ready to go back to the site to set boundary monuments, for example, I'm going to be on a corrected basis. If I don't have that by then there is a danger of it never getting done.?ÿ And I'm always thinking of jobs as the potential starting point for a future job in the neighborhood. I was assuming that the OPs typical job is boundary work, where he might spend a day collecting found monuments, spend some time in the office, then return to set missing monuments.?ÿ

With a mind to reusing data in the future - If I establish points on the NAD83(2011) datum that I want to reuse 5 years from now when NAD2022 is de rigueur ...... If used an RTN to establish my coordinates then shifting?ÿ them onto the new datum will be a translate-rotate-move operation. Probably OK, I guess, but a bit crude, IMO.?ÿ If I use OPUS to?ÿ position the base I case obtain a correct position for the base on any new datum by resending the data to OPUS, which I can enter into my StarNet project and have updated coordinates for everything in the new datum. So that influences my preference for using OPUS rather than an RTN solution.

Also an influence is the data sheet record OPUS produces, which I like to have over just a simple coordinate without metadata.?ÿ

@mark-mayer Excellent outline Mark!!!

That pretty much follows the same SOP as I have used for decades (even before OPUS). I suppose that you could equate that to leaving "fossilized foot steps" that could be recovered nearly forever, as opposed to those that disappear in the first wind.

Loyal?ÿ