Has anyone tried a Trimble R12 under canopy?
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I did some testing this summer with an R10 with an RTK base nearby, tracking all available constellations. As long as there were no large tree trunks blocking the signal, I got excellent results, proven by a high accuracy conventional tie between the base and rover monuments. But, when I tried it with large tree trunks (which would totally block the signal, not so good. Makes sense. The R10 with 4 constellations worked well even in a high multipath environment, and the R12 supposedly works even better. The reason I did the test is that we do a lot of woods check points for Lidar, and up til now we used a total station to survey in from a pair of points in the open, this test proved that with so many SV's available you can get decent results (<0.03 m) with a base nearby.?ÿ
Here are some pics of the test area...
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Here is a video of the site, gives a better idea of what the canopy looked like. As I said, I had little trouble at all initializing and getting good results.
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I was chatting with a vendor at our convention last week. They don't have an R12 yet, so I'm guessing there hasn't been much testing of the unit. Your pictures look similar to some lines we ran recently. The R10 worked in canopy but better in the afternoon than in the morning. The R12 is supposed to be even better, I'm interested to hear from some real world testing.?ÿ
I've done a topo in sparse to dense oak tree woodland, smaller trees, 20 to 30 feet high with R4 model 3 receivers and it worked surprisingly well.?ÿ Found some 20 year old control points set by my predecessors and checked very well, well within our accuracy needs.
Conifers, especially tall conifers, especially in the bottom of a canyon are a lot more challenging.
We just bought a second generation R10 a few months ago.?ÿ I'd say I'm happy with the way it performs in a poor environment but it still doesn't work miracles. ?ÿI'm also curious how the R12's work, its my understanding its a software upgrade to change a R10 to an R12.?ÿ
I looked into this a bit and found it may be water. Needles have high water content and water blocks/interferes with signals. Would be similar to performance in deciduous when leaves are wet from rain. I haven't tested the theory.
@John H. Were these single shots or repeatable with another constellation 4-6 hrs later.
@DavidL. "a software upgrade" => Speaking for GNSS units it's not so clear what exactly is a software upgrade. From what I heard from Trimble folks a software update is also an update of the chipsets used, these chips are faster have more processing power and updated algoritms for real time calculations. To my understanding this is different hardware and much more than a simple software update on an R10.
does this make sense??ÿ?ÿ
The R10 Model 2 has the upgraded chipset.?ÿ It has the same internals as the R12.
I did shots at different times of the day, and different days. Always a Reset followed by an init, and then an observed control shot. Init times were a bit longer than in the open, but still always under 1 minute. While there were 25+ satellites up, I was getting 10 to 15 in the solution.
A few weeks later I was in far northern US on the border with Canada (almost 49° latitude), and I tried to get some positions in a woods with big 50 cm diameter tree trunks around, would not initialize, had to move away from the big trees. Worked OK there once I was just under foliage, not near big blocking tree trunks.
Dry and lower humid days under canopy GPS can work. Working with different rod heights and finding a location for the receiver to obtain best signals is a factor.
I agree with Karoly about the type of canopy.
Pine trees, cedars and especially any canopy when it is wet, even the day after rain when the humidity is still high and everything is wet can reduce the effectiveness of the receivers.
Still, I look forward to the late fall to before spring when all the leaves are gone.
Hey John, I've been curious about the R12 and then saw this thread, now curious what you meant in: "Always a Reset followed by an init"
I know 'init' is an initialization, but what you mean by reset? A new point record in TA/TSC? Or meaning physically moving the antenna/receiver/bipod?
Now after absorbing this thread and Gavin's xyHt article, I'd LOVE to see you repeat the same experiment with an R12.
Jeff: In Access under Measure...RTK Initialization... there are several option to initialize, depending on what receiver, what style, etc. Right now, connected to VRS with an R10, there is Reset RTK, Reset SV Tracking, and Known Point. Of course the receiver usually initializes on-the-fly (OTF).
Reset RTK just re-initializes the solution.
Reset SV Tracking drops all satellites, reacquires them, and then re-initializes the RTK solution. We usually do an observed control observation, then Reset SV tracking, and then do another OC. This does not get rid of multipath if done right after the first init, but it will "refresh" everything, and can detect a bad initialization (very rare, but can happen in shaky sites with lots of obstructions)
This is from an older manual...
