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State Plane RTK
Posted by VRMTSRVY on February 27, 2017 at 3:17 pmI am new to using a base / rover combo for RTK (using RTN in the past) and I do not yet have any post processing software. My question/hope is that I will be able to go to a jobsite, set up the base using a “here” position while at the same time collecting raw data at the base while using the rover form the here position RTK. I was hoping I could then post process the base data to get a good state plane cord. and use the post processing software to “adjust” my RTK shots horizontally and vertically to correspond to the post processed base.
Is this possible? Is there a better way to get on state plane with more accuracy than RTN or if no cell service is available?
I will also be using the PP software for static observation…any suggestions on software?Thanks!
adam replied 7 years, 5 months ago 14 Members · 23 Replies -
23 Replies
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VRMTSRVY, post: 416019, member: 7295 wrote: Is this possible? Is there a better way to get on state plane with more accuracy than RTN or if no cell service is available?
Sure it is. Send the satellite raw data file into OPUS to get an accurate position for the base. Then you could simply shift the coordinates collected in CAD (or in EXCEL) onto the OPUS derived base position. That’s what a lot of people do.
I prefer to use StarNet to recalc the coordinates using the collected vectors and the OPUS derived base position.
You could also reprocess the raw data in the post processing software of your choice. Lots of options here. It may even be possible to enter the correct base position coordinates to your dc and do the recalc there, although I’ve never tried that..
Always remember that with any GNSS work you are collecting measurements between 2 receivers. You are not collecting coordinates. Coordinates are being computed from the measurements and the input assumptions.
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Great! Thank you for the response. I was hoping that was the procedure.
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2017 is a good time to rtk.
Javad flow is:
Start base, autonamous. Most of the time, it’s within 3 feet.
Work all day.
Return to base, download base data to rover.
Return to office, or wifi area. 20 minutes later, it returns the shift, and shifts all the days data, and the base, to be spc.
Slicker than snot!
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If you are using SurveyPro, you can upload the OPUS email as a txt file into the data collector, and import it into the job, and it will automatically update the base and all associated shots.
I have, of course, simplified it here in this forum, but it is not much harder than what I have typed to adjust it straight in the collector.
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Trimble Business Center works wonders but may not be the answer for your establishment. TBC can process RTK/RTN and all sorts of static data as well as send files to OPUS.
T. Nelson – SAM, LLC -
Just be aware, that if the “HERE” position is quite a bit off, you might have improved results reprocessing the observed RTK data relative to your final base position, not sure if it is super critical (probably depends), BUT my PP package gives a warning if the shift is over a couple meters and recommends reprocessing, it is up to the user to either accept that shift or re-process.
I ALWAYS collect raw satellite observations on both the base and rover, you can fix a multitude of sins if you have raw data, much less if all you have is coordinates in your rover at the end of the day. Memory is cheap, you do have to have the PP software though and in my opinion it borders on criminal for vendors to even consider selling a kit without that in the bundle. RTN’s or roll your own RTK isn’t the end all to GNSS surveying.
SHG
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If you want more redundancy: Start the base at Here, Occupy the points you want to locate, Move the base, Start the base at a 2nd Here, Occupy the points again. Back at the office submit the base files to OPUS / OPUS-RS. Using the OPUS positions and the RTK vectors you could do a least squares network adjustment. With Trimble equipment you have to record the QC1 / QC2 to include the vectors in a network adjustment.
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plazio, post: 416112, member: 193 wrote: If you want more redundancy: Start the base at Here, Occupy the points you want to locate, Move the base, Start the base at a 2nd Here, Occupy the points again. Back at the office submit the base files to OPUS / OPUS-RS. Using the OPUS positions and the RTK vectors you could do a least squares network adjustment. With Trimble equipment you have to record the QC1 / QC2 to include the vectors in a network adjustment.
Welcome back Peter, hope that you are doing well…and good post too!
Loyal
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plazio, post: 416112, member: 193 wrote: Move the base, Start the base at a 2nd Here, Occupy the points again.
Assuming the base has a clear sky view, I’m not seeing any advantage in moving it. Revisiting the points and tying them again from the same base provides the redundancy necessary for an adjustment. That’s pretty much my SOP when using RTK for control. (Most of the time I use a public RTN base — UCD1, a CRTN station about a click-and-a-half from my office — so sky view isn’t an issue. And I couldn’t move the base even if I wanted to!)
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plazio, post: 416112, member: 193 wrote: If you want more redundancy: Start the base at Here, Occupy the points you want to locate, Move the base, Start the base at a 2nd Here, Occupy the points again. Back at the office submit the base files to OPUS / OPUS-RS. Using the OPUS positions and the RTK vectors you could do a least squares network adjustment. With Trimble equipment you have to record the QC1 / QC2 to include the vectors in a network adjustment.
I must say I love this post, only thing I would add is to tie bench marks if elevations are of any interest and include them in an adjustment
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The nice thing about having post processing software is that you can get good quality solutions on short baselines with relatively short occupation times. We have a dense enough RTN that there’s always one or more CORS in relatively close proximity.
TBC has a very handy Internet Download tool. It looks at your project location, gives you a list of the nearest CORS sorted by distance, and automatically retrieves the CORS data that corresponds with your static sessions. I process the location of temporary base points fairly frequently, and generally use OPUS only as a check.
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Here’s an example of a Point Derivation report on a base point I computed last week. This one had over six hours on it, so everything is nice and tight. The Office Entered position is the autonomous position from the receiver.
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Jim Frame, post: 416132, member: 10 wrote: Assuming the base has a clear sky view, I’m not seeing any advantage in moving it.
That is often an assumption that cannot be made. Moving the base puts it in a different multipath environment. I kind of like plazio’s methodology and may try it sometime.
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With modern gps, and multipath mitigation, the main advantage of moving the base, is to double check the antenna heights. However, with some gps units, whose multipath mitigation is not keeping pace, I see a potential problem. However, as Mike says above, with totally clear sky… It should not be an issue.
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I confess… When using a second base, and it gives me virtually the same numbers, it does give me “the warm fuzzies”.
More discussion? -
Nate The Surveyor, post: 416353, member: 291 wrote: I confess… When using a second base, and it gives me virtually the same numbers, it does give me “the warm fuzzies”.
More discussion?Using a second base means there are multiple checks, not just the HIs.During the process of converting from an autonomous pt to a CORS derived pt at the base things have been known to happen, just one thing that can go wrong
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Nate The Surveyor, post: 416035, member: 291 wrote: 2017 is a good time to rtk.
Javad flow is:
Start base, autonamous. Most of the time, it’s within 3 feet.
Work all day.
Return to base, download base data to rover.
Return to office, or wifi area. 20 minutes later, it returns the shift, and shifts all the days data, and the base, to be spc.
Slicker than snot!
NWhat is the total dollar investment fer this slicker than snot contraption?…base, rover, software, learning curve?
Thank you
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If you want a 35 watt radio, as I did, and did not opt for any of the cell phone options, 21,500 will get you going. I think I paid around 21,300, with shipping. But, I already had tripod, tribrach, base battery set up etc.
Now, when you add in the learning curve… IF you are a reasonably intelligent person, and know how to work with SPC, you can be financially productive in a day of training.
There are things I am still learning. I’ve had it over a year. They have added, MANY things, since I got it. Occasionally, as they add functions, some things don’t work for a day…. It’s the price I accept, to be cutting edge.After I got it, I have NOT used my old gear. Once you see what it can do…. Bam! We on!
My favorite is to be in an impossible place, watching it click away… and then to say to my self, NO WAY, and repeat it, and repeat it, and all the coords are within 0.04′ or 0.06′ of each other, horiz. and within 0.12′ vert. And, it then allows you to make a weighted average of those 4 shots.
N
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Nate The Surveyor, post: 421012, member: 291 wrote: My favorite is to be in an impossible place, watching it click away… and then to say to my self, NO WAY, and repeat it, and repeat it, and all the coords are within 0.04′ or 0.06′ of each other, horiz. and within 0.12′ vert. And, it then allows you to make a weighted average of those 4 shots.
My new Trimble R8s will do that, too. It did cost somewhat more at $27K for the pair (no dc, already had one). And the radio is 0.2 watts.
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