@robertusa While under thick canopy, it is always good to check and recheck the repeatability. Not only is there a second shot, there is a stakeout of the point recorded. Not only do I shoot the same point again, I'll walk away, do other work and return to see if I had good data. So far, I have had good results.
Now considering what I'm after, is it data for a super collider or to show landscaping features? The right tool and processes for the job at hand is the way to go.
Hello to all I have tested this afternoon CHCNAV i90 with Trimble r12i?ÿ in the canopy results with the same. In some parts between tall buildings, i90 was not able to fix.
What are your thoughts?
I know that Trimble is a well-named brand but I have never worked with Chinese receivers.
Are they reliable?
One cost 20.000 $ with data collector and the other 5500$ with data collector also.
I can say that I have been improved.
Any thoughts??
Can anyone answer me if Chinese and low-cost receivers have a confidence level low in order to have '' fixed'' solutions?
For what it is worth, I like the device built into the Javad, that Quality Checks the shots, in the field. However, (Give Trimble his due) I wish Javad had the tilt feature that apparently Trimble has. It seems that Trimble knows direction, without magnetic interference. Javad's tilt direction is MAGNETIC. Magnetic fails, when shooting a monument, that's under a METAL fence corner brace, that interferes with magnetism. Try tilt feature, when shooting a METAL BUILDING, With magnetic direction control.
So, tell me how accurate Trimble tilt works, since it is not magnetic? It honestly BUGS me that their tilt appears better than Javads.
Tilt is not everything. But its usefulness is curbed, by being magnetic.
I hope you are having a good day. Raining here. Just saying "It's magic" is not enough. Saying "it's an IMU" Only leaves me in the dark. Do you know how an IMU determines Direction?
CURIOUS Nate
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I don't have an R12 (only a couple of R10-2's without tilt), but my understanding is that you first need to be in motion, then it uses the change in position to orient the IMU (i.e. it computes the direction you are moving, compares it to the IMU, and applies the difference). Any IMU will drift over time, so it is constantly using the GNSS positions to update/correct the IMU.?ÿ
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@nate-the-surveyor I have read how IMU works and i Can not trust them 100%.
My other thought is how a low-cost receiver like CHC can be compared with trimble r12i as in my test gives accuracies of 2-3 cm difference in tilt mode and works pretty good under canopy.
Also, I think that Chinese has a low confidence level inside of their motherboard chipset in order to give '' fixed'' results.
Does the IMU work well in extreme canopy? Or, does it degrade the tilt direction in canopy?
If it has a gyro inside, then I can see it working. If not, it may degrade.?ÿ
Curious Nate
I have read how IMU works and i Can not trust them 100%.
I would hope that you're not trusting your GNSS results 100% either...
We currently have about ~20 R12i receivers in the field. We have found that RTK+IMU solutions are generally repeatable to ~3-4cm under typical conditions. The IMU adds about ~5mm of positional error (RMS) plus less than 1cm if tilt is below 30 degrees. That's about 15mm on top of the ~2cm that is common for RTK, so it generally lines up with the specs.?ÿ
I wouldn't go with a particular manufacturer based on a single feature, or the fact that a single item does slightly better than a competitor in one area. Other things are at least as (I would say far more) important for productivity, such as how intuitive the field software is, mechanisms to push data to/from the office, and ease of post-processing. It's better to evaluate the whole package.
Does the IMU work well in extreme canopy? Or, does it degrade the tilt direction in canopy?
You need a good GNSS position solution to combine with the IMU heading. Under heavy canopy it's more likely the the operator will be leaving the receiver stationary to allow the GNSS solution to converge. When that is the case, as @john-hamilton mentioned, there will probably not be enough motion to compute an IMU heading and combined solution.
It's possible to thread that needle, but in practice it is increasingly difficult as the canopy gets thicker.
@rover83 Would you ever trust a Chinese receiver?
I would think that the confidence level is at 90% at Chinese receivers that's because they give fast solutions.
But is there any chance to give false ''fixed'' solutions?
It is hard to speak to the specifics of i90 comparative performance without knowing what options and OEM board is installed in it.
The i90 is available with a Trimble BD990 engine or a UniCoreCom OEM board (and perhaps others.) While not as varied in component possibility as the i70, I believe that there are a variety of modems, uhf, bluetooth available.
If the unit has a Trimble BD990 OEM board, there are a series of tracking options (you want them all), and you want the MaxPro option with OEM firmware 6.06. (There are slightly newer versions, but I would personally hold back for a while -- it is currently Nov 2021 when I write this.)?ÿ
If the unit has the UniCoreCom OEM engine, then there are other considerations.?ÿ
I used to be able to guess what the options were by price and full part number, but I can't do that anymore. I have to connect to a head with a serial cable, put in passthrough mode and then use PPP to connect to the internal engine and poke around. WinFlash reports 5.46 for devices with 6.06, and the web interface matches winflash.
There is also a possibility of changing performance by changing tracking options. Probably best to check everything and let the engine work it out on it's own.
Finally the correction source is important. For the i90 to work best, it needs a fully enabled RTCM3.2 stream or sCMRx. sCMRx is scrambled CMRx and it is not compatible with CMRx by design. If you were going to do a head to head comparison, best to use either a R12 or i90 base broadcasting RTCM3.2 with everything enabled and tracking to 5 deg.
@mark-silver Why the huge price difference in prices between Trimble r12i that cost 20.000 $ approximately and the other i90 that costs 5000$ ? Can you explain this?
Maybe is a marketing game?
I have a feeling that the Chinese maybe give false float solutions sometimes (maybe they say fixed in DC and it will be not) in the other hand Trimble says that the accuracy of that data collector says is real.
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I don't think the $5200 price in the USA for a Trimble based board is possible because of tariffs. A BD990 based i90 without IMU Tilt is $7650 with IMU Tilt $10,300 (from a reputable US dealer with support and service.)
I think that $5200 might be possible without inbound shipping and without tariffs on a non-Trimble engine device without IMU. That is a lot of withouts, I know.
Trimble receivers command a higher price because of an extensive support network with local dealers. The R12's are part of an extensive suite of integrated solutions: Scanners, Mobile, UAV, Robots, monitoring, infrastructure, scanning, remote sensing, levels, guidance, water management, resource utilization. Trimble has extensive software products also.
These differences in price exist in all products. Wrist watches, vehicles, homes, backhoes, welders, trailers, RV's, drones... Sometimes they make sense, sometimes they don't. A lot of the difference can be in marketing costs alone.
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