I observed a survey crew working on a right of way today in some rather heavy cover it appeared they were using Topcon receivers. Our equipment is a few years old I??m wondering if it??s time for an upgrade does the new stuff really work that well? Anyone experience working in heavy tree cover?
The best unit for working under tree canopy is still a TS.
That said, more satellites means better performance under marginal conditions. If you aren't receiving all the available constellations you will benefit from an upgrade.
The algorithms involve calculating statistical probabilities rather than absolute solutions.?ÿ Some brands will get "fixes" by accepting noisier data than others will. That is kind of a crap shoot. You can get fixes more often under poor conditions by accepting the possibility that some of those fixes aren't really fixed at all.?ÿ ?ÿ ?ÿ?ÿ
My local competition uses Topcon with the latest upgrades and I constantly find their half foot errors between monuments under canopy.
Everytime they could have shot in two points and shot a hundred feet under the deep canopy of a large oak or pine an cedar trees and got it right.
A longer static session would have got it right too.
I got a Trimble R10 setup two years ago. They are unbelievable in trees. They get positions in spots where my old 5700 system wouldn't even give me a 16 foot float. They don't really fix, they tell you the statistical precision they are currently receiving. You decide if it's good enough or not. If your current system isn't Glonass you will be amazed.
Unfortunately you won't be able to give your stuff away if it isnt Glonass.
I use a Trimble R10.?ÿ The only time I find myself needing a total station these days is when a large percentage of the boundary or topo area is covered in tall pines.?ÿ ?ÿ
I would have purchased a Javad unit were it not for the incredible Trimble customer support at Duncan-Parnell here in NC.
With all the satellites available, I don't think the brand really matters anymore, as long as you are using sound practices and understand the built-in limitations of all GNSS units in canopy. All new receivers will (ultimately) give the same results if you know how to use them and understand how they process and receive data - time and repetition being the most reliable factors. I've heard a lot of childish Chevy vs Ford style debates over what brands, usually among people who've only tried one brand ever. They're all working off the same satellites after all. In the end, all that matters is that you can produce the same coordinates over and over again within whatever your acceptable tolerance is.
I somewhat disagree. Yes, using all the additional constellations definitely helps. In a post processed static scenario I think the brand does not matter as much.
But, this is not post processing. RTK depends on the RTK engine on the receiver, and each brand has their own engine. Trimble recently came out with a "ProPoint" upgrade for the R10 (model 2 only) and R12. I have done tests using R10's with and without the upgrade (I have two R10 model 1 that are not upgradeable). The real time solution of all those satellites requires a faster processor in the rover.Noticeably faster init times with ProPoint. But the standard R10 still got the fix, just took a little longer. That was using GPS/Glonass/Galileo. At the time I was having issues getting Beidou in the solution, that has now been resolved, but I haven't done testing in the woods yet using the additional Beidou satellites.?ÿ?ÿ
I should add that my woods point (heavily wooded, with foliage) was also surveyed conventionally to an accuracy of ?ñ3 mm with respect to the base. The RTK obs were within ?ñ2 cm.?ÿ
Javad is hands down the best I have seen, it amazes us daily!!!?ÿ ?ÿ
@john-hamilton I agree with what you're saying. Trimble makes amazing stuff and I'd have it any day. Every salesman says their stuff is the best and no one can match it, but they can't all be the "best". It's probably closer to the truth to say there are several "top shelf" manufacturers that all make excellent products and you'd be pleased with any of them.?ÿ I just want the consumer to have a choice, and I think there's several good options, especially among the major brands.
I would urge caution relying on the stats on the display. I have found Trimble, Topcon and Leica to be overly optimistic by a factor of about 2.5. It's not just in canopy either.
The precisions shown on all major brands are at the 1-sigma confidence level. And likely overly optimistic.
During my stint as a a trainer and tech support for a Trimble dealer we would regularly get the question, "Why doesn't the field software display precisions at the 95% confidence level, since that is the industry standard?" I asked it too, because I would at least like the option to change it from 1- to 2-sigma if I wanted to.
The answer was always, "Because the competition only shows 1-sigma values, and the competition's dealers would absolutely take advantage of customer ignorance (laziness) and point out the 'less precise' values on our gear." Their data showed that sales would take a sizable hit from that.
I understand the reasoning, even though it annoys me. Based upon my experience in that role, a large percentage of GNSS positioning system users (I would say 60%+) do not understand confidence intervals or any aspect of error propagation.
Best Units...
?ÿ
Can't go wrong with US Survey Feet; traditional, time tested, and made in the good old U.S. of A.?ÿ ?ÿ?ÿ
1896 called. They want their foot definition back. Once you go to international feet you'll never want to go back.
That's funny because I was just complaining on Twitter to an acquaintance who edits a semi-academic journal that the latest issue was taking too long to deliver because they were using 1896 delivery methods for philosophical reasons.
Local Culture: A Journal of the Front Porch Republic is published semi-annually. It is dedicated to the conditions that best conduce to human flourishing: the virtues, political and economic decentralization, localism, liberty, respect for natural limits, tradition—especially the humane tradition in arts and letters—and living arrangements built to human scale.
I'm a Javad fan.
To collect a woods canopy shot:
1.) Mine is set up to gain a fix, and dump automatically, 7 times.
2.) Then, to store all the fixed solutions inside a 0.16 dia circle. For 120 seconds.
3.) Then to do a couple more fix/dump routines.
Meanwhile, it's comparing various geometric solutions, from various satellite configurations.
And, gathering the data via radio, to post process the point, and process it simultaneously.
So, a normal deep woods shot, can take 2-5 minutes.
Then, it gives you a look at the shot scatter, so you can decide if 0.10 is good enough. If not, shoot again. It then does a weighted average of all your shots.
I do this in the worst places. Rarely is there more than 0.07' difference.
This allows you to work all day, but when configuration is poor, take an extra shot or 2 or 3.
Most places in mild woods are 2 to 3 minutes. Depending on needed accuracy. If it is important, get it 3x, and average.
I wish others had this unit, because it is consistent, and solid.
The cogo is a bit clunky. But it will tell the truth, if you let it do it's thing.
Some of the slowest places is between 2 buildings, and the like.
O well. Jonquils are coming up.
And frogs were roaring last week.
N
I do this in the worst places. Rarely is there more than 0.07' difference.
If you come back to the same spot 2-4 hours later are you still within 0.07'?
I'm a Javad fan.
Well you've been playing that awfully close to the vest.
I do this in the worst places. Rarely is there more than 0.07' difference.
If you come back to the same spot 2-4 hours later are you still within 0.07'?
I'm not in the jungle like Nate, but yes, 2-4 hours, 2-4 months, the new engines do work. I've had the R-10's long enough to test them in deep canopy with months and years between locations to the same monument and .07' is easily achievable, even in Ponderosa canopy. My biggest issue is time of day, sometimes it's best early, sometimes it's best later in the day.
Just yesterday I completed a traverse in a local suburban neighborhood. The process was to hit all the points with GPS, then traverse through them all, and simultaneously adjust the vectors and traverse data using StarNet.
The "entered provisionals" are the coordinates as determined by GNSS alone, using a Leica GS18 base/rover pair (2 x 90 second RTK observations on each point) . I've set the GPS vector standard error scaling higher than need be, to more heavily weight the traverse data. The neighborhood is not deep woods, but there is plenty of obscured sky.
Just yesterday I completed a traverse in a local suburban neighborhood. The process was to hit all the points with GPS, then traverse through them all, and simultaneously adjust the vectors and traverse data using StarNet.
The "entered provisionals" are the coordinates as determined by GNSS alone, using a Leica GS18 base/rover pair (2 x 90 second RTK observations on each point) . I've set the GPS vector standard error scaling higher than need be, to more heavily weight the traverse data. The neighborhood is not deep woods, but there is plenty of obscured sky.
That looks deep to me.