12 Mile Single Baseline RTK - Four Points... Nothing but net

[Shawn Billings]

Yesterday we were working on a small job about 12 miles from the office (as the crow flies). I had a Triumph2 broadcasting corrections over TCP from our office internet WiFi. At the site I observed four points by RTK for five minutes each with a Triumph-LS. I then setup a total station on one of those points and turned in the other three. All were within about 300 feet of each other. I then did a Helmert transformation of the total station coordinates to the RTK coordinates, allowing the software to determine the best rotation and translation to transform the total station system to the RTK system. I forced the scale to remain at 1. Points L001, L002, L003 and L004 were RTK derived. I was setup on T003 (L003) and turned T012, T002 and T004. The differences between the two sets of coordinates are as follows:

Point# Northing Easting Elevation
Delta-Y Delta-X Delta-Z
----------------------------------------------------------------------------
L001 872.791 405.084 419.534
T012 872.767 405.061 419.575
-0.024 -0.023 0.040
L002 904.213 702.294 410.933
T002 904.227 702.298 410.933
0.014 0.004 0.000
L003 899.143 482.485 415.170
T003 899.147 482.487 415.266
0.004 0.002 0.095
L004 170.840 530.628 424.130
T004 170.846 530.644 424.023
0.006 0.017 -0.106

I was very pleased and surprised to see this sort of accuracy from a single baseline solution at 12 miles. Five minutes is a fairly long observation time, but in the grand scheme of things four points at five minutes each is 20 minutes of observation time.

 

[Javad]

Shawn this is a good story to tell. Please write it for publication. Your name or anonymous, as you like.

 

[Nistorescu Sorin]

There will always be pros and cons opinions in terms of RTK surveying techniques and methods. Some "guided measurement modes" could be one step further providing the ultimate in user support, but they can be difficult to implement.

Also could be interesting a triple frequency RTK test (GPS,GLONASS,BEIDOU), with two Triumph LS or Triumph-1M/Triumph LS (base-rover) receivers. Probably someone from Asia-Pacific zone can do it. The test should be done on several monuments that are in very good condition.

Regards.

 

[William Holt]

Very good information Shawn!!

I didn't even think of this when I purchased the LS ... but the GPS we have been using is controlled by a data collector ... we can unplug it from the GPS receiver and plug it into our total station and gather data in the same file. When we plug it back into the receiver all of the new points are there and we only have to download and reduce that one file into cadd.

Has anyone come up with a work around for this with the LS? Can the LS be configured to act a Data Collector or do we have to find a way to transfer the file to the DC in the field? This was a major consideration when we purchased the previous GPS ... it just slipped my mind when considering the LS ...

WEH

 

[Matt Johnson]

Very good information Shawn!!

I didn't even think of this when I purchased the LS ... but the GPS we have been using is controlled by a data collector ... we can unplug it from the GPS receiver and plug it into our total station and gather data in the same file. When we plug it back into the receiver all of the new points are there and we only have to download and reduce that one file into cadd.

Has anyone come up with a work around for this with the LS? Can the LS be configured to act a Data Collector or do we have to find a way to transfer the file to the DC in the field? This was a major consideration when we purchased the previous GPS ... it just slipped my mind when considering the LS ...

WEH

J-Field can't be used as a data collector for total stations but coordinate files can easily be exchanged with a USB thumbdrive between the LS and data collectors. There is also support for bluetooth file transfers.

 

[William Holt]

Thanks Matt ... I'll see if we can make that work ...

WEH

 

[Shawn Billings]

Matt's right on. If you have a USB port on your data collector, keep a thumb drive handy. I advocated for all kinds of creative ways to beam files from one device to another, but I believe the thumb drive is the simplest method, if your collector can support it.

 

[Shawn Billings]

Javad is going to be releasing a new version within days. We're working hard to test this new version to make sure it is as robust as possible. Part of this new release is a new V6+ RTK engine. I've been testing it quite a bit at a range of 2.55 miles and 9.5 miles as well as on a point I would classify as being under moderate to extreme canopy. I will be posting results soon of these tests. I am absolutely blown away. I can't explain the results I'm seeing, but the results are very good. I'm seeing almost no difference in precision between points collected at 2.55 miles and points collected at 9.5 miles. Regarding points under canopy: along with the new V6+ RTK engine is an additional fix verification tool called "Validate". Validate is a final reset of the engines at the end of an occupation. This is a quick check of the fix quality at the end of the occupation, meaning that this will allow for the greatest amount of time to transpire between Phase 1 verification and the last epoch of Phase 2. This will provide a robust means of verifying those seemingly good solutions in very bad places.