Testing TruPulse 200 X

General discussions of measurement techniques and the results of testing of techniques and equipment.

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dbhguru
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Re: Testing TruPulse 200 X

Post by dbhguru » Wed Dec 25, 2013 12:14 pm

NTS,

I'm now up to 30 trials and the difference between the Bosch GLM80 and GLRM825 and the TruPulse 200X with respect to direct distance is at an average of 1.9 inches. Trial distances vary from 12 to 109 feet. I'll gradually extend the range, but at this point, I'm satisfied that the accuracy of the laser is within +/- 2.0 inches or 5.08 centimeters of a wide range of distance. There may be ways to reduce the error to perhaps +/- 1.5 inches, but I doubt that I can devise field experiments to confirm the results to a greater tolerance level. For the present, I'm willing to go with the +/- 2.0 inches.

Testing the tilt sensor is more time consuming and technically challenging, but that test is on the horizon. I'm expecting accuracy to +/- 0.1 degrees, but when in doubt, test.

When the tests for the direct distance shots of the laser and angles for the tilt sensor have been completed, it will be time to look for special applications.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Karlheinz
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Re: Testing TruPulse 200 X

Post by Karlheinz » Wed Dec 25, 2013 8:30 pm

Bob,
please tell me, what is the firmware version of your TruPulse?

I mounted the TP200X and the Leica together on a common platform. The rear edge of the Leica, which is its default reference setting, aligns with the tripod screw of the TP, which is its point of reference. Setting the Leica on tripod screw as the reference, I avoid, because after each on/off it will reset. The exit lenses of both lasers are on the same level and I calibrated the two Lasers to the same horizontal level. So I can compare the readings of both devices directly and easily. Calibrate accurately is difficult because the TP200X is covered with rubber and has no smooth abutment surface.
2013-12-20-21.07.02_k.jpg
2013-12-20-21.08.14_k.jpg
I tested the TP200X with this device combination at close range inside my house (<10m) a bit. A centimeter exactly value is displayed each time. In almost every repetition of a measurement, when the position on tripod is unchanged, I get back exactly the same reading. This value, however, may be wrong to up to a few cm, as the comparison with Leica shows. The small display steps of 1 cm and the almost complete reproducibility in each measurement give the appearance of high measuring accuracy, but this is not the case. My readings were within a tolerance range of -3 / +7 cm (typical -2 / +3 cm). But I have the measurements not documented. This accuracy corresponds in about the manufacturer's specified accuracy.
These measurement results from close range confirm that Leica in this case of application is the TP vastly superior, that's no surprise. However, for the close range, I do not need the TP. Crucial for me will be as well measurements to treetop succeed.

Karl

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KoutaR
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Re: Testing TruPulse 200 X

Post by KoutaR » Thu Dec 26, 2013 5:11 am

Bob & Karlheinz,

Is there a relationship between distance and error or is it random?

Kouta

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dbhguru
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Re: Testing TruPulse 200 X

Post by dbhguru » Thu Dec 26, 2013 12:27 pm

Kouta and Karl,

Here are the results of 36 trials. So far, I haven't confirmed an accuracy pattern that I'm confident will hold, although I do suspect that there are strong and weak distance intervals that relate to the interval computational algorithm that LTI uses. So, my guess is that we'll see a random pattern superimposed on a predictable pattern. It is going to require a lot more testing in a range of conditions, but I expect that we'll eventually be able to assign probabilities to TruPulse accuracy in an overall sense, plus identify strong and weak intervals.

Here is a summary of the 36 trials conducted to date.
BoschVSTruPulse.png
BoschVSTruPulse.png (18.06 KiB) Viewed 1284 times
Lots more to come.

Karl,

I'll ask LTI about the firmware #. BTW, that is a sophisticated setup you have. I hope Michael Taylor reads your posts.

NTS,

I've named my new TruPulse Sparky. Matt, if that gives you any ideas on tree humor at my expense, please have at it.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Karlheinz
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Re: Testing TruPulse 200 X

Post by Karlheinz » Fri Dec 27, 2013 4:31 am

Kouta,
I detected no regularity in the error variance.

Bob,
our two devices show the same behavior and I agree with your assumptions.
With firmware version I mean the firmware revision ID number which you can request by pressing the mode button. To me firmware version 1466 is displayed. I guess they are still working on improving their firmware. Sad fact is that a new firmware can not be obtained and loaded on the Internet, but you must send the device to LTI.

Do you also have the problem, I described in My Rangefinders TruPulse200X, Leica and Nikon, that all measured values ​​are deleted after 90 seconds and you can not prevent it?

Karl

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Re: Testing TruPulse 200 X

Post by dbhguru » Fri Dec 27, 2013 8:46 am

Karl,

Yes, the firmware # is 1466, and the display does clear after 90 seconds. On the firmware issue, I was told this past summer by LTI that future firmware updates would come via the Internet. Maybe that intention has changed. I'll check it out and let you know. Maybe it is a more distant future plan.

I've given the Gate function a good workout on my 200X and am quite pleased with its performance. Our house is surrounded by fairly tall trees. The top and base of a tulip poplar can be clearly seen from our upstairs bedroom window. The base is slightly over 43 vertical feet below my position at the window and the top is slightly more than 82. The tree's top cannot be seen from our deck at a lower level, so I have always had to try to measure it with less accurate instruments that ignore vert close targets. But now I can take measurements from inside utilizing the accuracy of the 200X. Sweet!

I have come to realize that I need to plan ahead when using the Gate function for the more distant trees with clutter partially obscuring both top and base, since the gate value needed for the top and base will usually differ. I try to find a spot on the trunk that I can hit without setting the gate. I remember that value and then shoot the angle to the top and do a quick secant calculation using the distance to the trunk and the angle to the top to get an approximate hypotenuse distance. I then set the gate to the trunk distance and measure height to the base. I reset the gate to slightly less than the hypotenuse distance and shoot the top to get a first crack at the height to the top. I then shoot at other tops, maybe having to change the gate if shooting to a more distant top that needs a higher gate value. It can be time consuming, but for really important trees, worth the effort.

Eric Newman, LTI's regional sales manager from Albany New York is going to participate in a re-measure of the Jake Swamp white pine in MTSF with me using the 200X. I will then systematically re-measure all of Mohawk's 160-footers, and work my way down. Using my TruPulse 360 for some and Nikon Prostaff 440 for others, I currently have the count of trees reaching 150 feet or more in Mohawk to 130. I don't know if I'll re-measure all 130 trees, but will certainly measure many of them. What kind of plans do you have for your 200X?

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Karlheinz
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Re: Testing TruPulse 200 X

Post by Karlheinz » Fri Dec 27, 2013 6:59 pm

Bob,

Derrick Reish, LTI's Sr. Product Manager, at InterGeo 2013 in October told me, that firmware update by Internet would not be possible. In the manual I find nothing about firmware update.
What kind of plans do you have for your 200X?
I don't have such great program as yours, Bob. I will do some tests to a target plate and compare distance and inclination with the Leica. I will check by shooting at a horizontal and a vertical bar if the reticle is aligned exactly to the laser impact point.

Of course I want to make comparative measurements at the few tall trees whose height we know exactly. I am hopeful that we will achieve a comparable accuracy with tape drop method. And of course, I want to remeasure trees, which we have measured so far with Nikon. I want to know how to assess our previous Nikon measurements. Hopefully that does not result in too large deviations - I'm afraid I might become very unpopular with the Nikon fans.

Karl

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dbhguru
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Re: Testing TruPulse 200 X

Post by dbhguru » Fri Dec 27, 2013 7:22 pm

Karl

We both may become unpopular with Nikon users. Heck, I may become unpopular with myself since I have lots of Nikon measurements in my database. But accuracy must rule.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Karlheinz
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Re: Testing TruPulse 200 X

Post by Karlheinz » Sat Dec 28, 2013 7:25 am

Bob,
I think the measurement to the tree top in cluttered environments succeed even less complicated. In a first phase of investigation I scan the tip, as I am used to do. Depending on the situation setting to Continuous or Farthest can be helpful. So I get out already, how far about it is to the tip. Then I can add a gate value and examine the tip in more detail. Finally, I'm doing the exact measurement on tripod.

Karl

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KoutaR
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Re: Testing TruPulse 200 X

Post by KoutaR » Sat Dec 28, 2013 9:17 am

Karlheinz wrote:I detected no regularity in the error variance.
Bob, Karlheinz et al.,

It would be important to know if that also applies to the angle measurements as it has a big influence on the height measurement accuracy. Ed once proposed the clinometer error is always the same, i.e. the same at all the angles; if so the clinometer error does not have any influence on the height accuracy. But I am not fully convinced. These rangefinders are highly sophisticated instruments; do we know all the error sources? One thing that arouse my suspicions is that according to the user manual of Leica Disto, the clinometer error is temperature dependent: +/- 0.1° at room temperature and max. +/- 0.2° outside the room temperature. Thus, the error is NOT always the same. But is it the same at all the angles at one given temperature? It is much more difficult to test than the distance measurement but I think SHOULD be tested. If the clinometer error, too, had a random pattern, it could result on errors of tens of cm when measuring a tall tree.

Kouta

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