Is the 0.0003' a typo? Shouldn't it be 0.003'? I survey in Florida, and I'm looking for a standard deviation from the mean specification when taking 5 measurements. I've been rejecting any measurement > 0.003'. At that point I stop the measurements and I remeasure. What specification do you use? Additionally, when I stop measurements and remeasure on my Leica LS10 it throws a wrench in the line leveling program. I think the program records the shot anyway and at the next station when I measure to the backsight, I get a distance warning error stating that I'm exceeding the maximum allowable distance. In other words, my distances aren't balanced. I'm working with Leica support to resolve the issue. Have any of you experienced this?
Probably not. With moderately careful handling individual readings that differ by more than 0.001' out of a geodetic quality digital level are rare. SD of the mean of several readings would be better than that. The question in my mind is how the operator is supposed to know in real time what a statistic like SD of the mean is.
If you are having trouble with measurement errors in the 0.003' range you might try shortening up your sights. Also, it could be that your tripod is a little shaky. Working beside busy roads, much less construction equipment, can impact precision.
The question in my mind is how the operator is supposed to know in real time what a statistic like SD of the mean is.
With the Leica DNA003, that's one of the statistics available after a measurement is taken.
With the Leica DNA003, that's one of the statistics available after a measurement is taken.
Well, that's embarrassing. I've been using DNA03, DNA10, and LS15 for over 20 years and never really paid enough attention to those numbers to comprehend just what they were.
meters and feet, oh my....
I think the program records the shot anyway and at the next station when I measure to the backsight, I get a distance warning error stating that I'm exceeding the maximum allowable distance.
Yes, the program does record the shot because even though the instrument is set to take 5 readings, in my case, if you press the [STOP] button the program assumes you're done with that reading. The reason for the distance warning was that I repeated the same FS reading unaware that the previous reading had already been stored. The program thought the repeated reading was the backsight reading for my next station (instrument setup). I think this is poor programming. This past Friday I had time to figure this out in the parking lot at work where I was relaxed and could think clearly.
I survey in Florida, and I'm looking for a standard deviation from the mean specification when taking 5 measurements.
I found my answer in the Survey Technical Guidelines Field Section of the Land Surveying Mapping and
GIS Section, Southwest Florida Water Management District. Please see the attached file.
Also, it could be that your tripod is a little shaky.
More like a shaky rodman. Probably a little muscle fatigue towards the end of a day. We've been trying to limit our sights to 200'.
We've been trying to limit our sights to 200'.
If you are trying for very high precision that may be a little long.
Here's a screenshot of my LS10 mean measuring mode. Will post something with realistic numbers tomorrow. This was not part of an actual run.
We are currently working on a bluebook leveling project that we repeat every 5 years and submit to NGS. We used to do it every year and then BB every five but now only the BB every 5. Subsidence monitoring
Here is part of the data file from a Trimble Dini12:
pre
For M5|Adr 96|KD1 0005 0005 32518|Rb 2.13913 m |HD 49.576 m |sR 0.00003 m |
For M5|Adr 97|KD1 TP 32518|Rf 1.52238 m |HD 46.006 m |sR 0.00004 m |
For M5|Adr 98|KD1 TP 32518|Rb 1.57102 m |HD 56.264 m |sR 0.00008 m |
For M5|Adr 99|KD1 TP 32518|Rf 1.58258 m |HD 55.573 m |sR 0.00004 m |
For M5|Adr 100|KD1 TP 32518|Rb 1.13987 m |HD 57.691 m |sR 0.00003 m |
For M5|Adr 101|KD1 TP 32518|Rf 1.75504 m |HD 56.971 m |sR 0.00002 m |
For M5|Adr 102|KD1 TP 32518|Rb 1.17264 m |HD 59.447 m |sR 0.00007 m |
For M5|Adr 103|KD1 TP 32518|Rf 1.76680 m |HD 57.771 m |sR 0.00002 m |
For M5|Adr 104|KD1 TP 32518|Rb 1.44462 m |HD 46.971 m |sR 0.00004 m |
/pre
In the above the Rb is backsight rod, Rf is foresight rod, HD is horizontal distance to the rod, and sR is the standard deviation of mean rod reading (3 readings). As per NGS, the max std dev is set at 0.00010.
We ran last week under good conditions: cloudy, little wind, and using a 3 m invar rod with struts. We only had one or two shots that exceeded 0.0001 m stdev.
I really wish Trimble would improve the dini, it was manufactured in a time when memory was not so cheap, and as far as I know has not been improved upon in years. My wish list for the ideal digital level:
autofocus
autolock (finds the center of the rod, which on an invar rod is relatively narrow)
remote trigger (so as not to slightly bump the instrument when shooting) - a trigger button with bluetooth?
more data in each data line. Currently you can have time or SDEV but not both, for example
longer "cover" on telescope to block the sun when low in the sky. It will often not shoot if the low sun is in the direction of the rod
an indicator light facing the rod showing when a shot is being taken (i.e. freeze, don't move) and when the shot is done
edit: (sorry, the pre and /pre did not work, these were supposed to turn on and off constant spacing)