Got the dc file uploaded from the field and processed the data...he mixed prisms (which I didn't want him to do but didn't specifically tell him not to). Most of the shots were to a Wild GPH1P (-34), a few were to a Trimble Monitoring prism (-40).
When I ran it with both prisms, I got a scale error of -1.29 ppm, and a constant error of +0.0015 m.?ÿ
When I ran it with only the Wild prisms, I got a scale error of -0.65 ppm, and a constant error of +0.0003 m, which is within the specs of the instrument (1 ppm ?ñ 1 ppm). When he gets back to the office I am going to compare the two prisms on the baseline between my pedestals (~135 meters) to see if the offset of the Trimble prism is correct (assuming the -34 is correct based on the above).?ÿ
One thing that is critical when going to a CBL is getting the temperature right (the instrument has an onboard pressure sensor, which I have verified is accurate). An error of 1?øC corresponds to 1 ppm.
the -34 is correct
-34 or -34.4 ?
@john-nolton uhmm yes me and him talked about our time in the USMC. He told me he was in the USMC. ?ÿBrought me his rifle i sighted it in at Corbin. I served in USMC. If he was not then he told a whopper. But i had no reason not to believe him. ?ÿSo that came directly from him. ?ÿI see you were in as well. ?ÿ
@bill93 The -34.4 is probably correct, but my software only goes to the mm. I may be able to modify it and see if it makes any difference.?ÿ
But I think there are other limitations in the process that makes sub-mm somewhat unattainable.?ÿ
@olemanriver?ÿ ?ÿA?ÿ WHOPPER?ÿfrom Glover; YES.
I wonder if there was a misunderstanding.?ÿ This profile has him drafted into the U.S. Army.?ÿ?ÿ
https://amerisurv.com/2017/03/24/in-memoriam-the-most-excellent-life-of-charles-charlie-glover/
@john-nolton well I reckon you were correct. He was drafted in the Aint Ready Marine Yet. ARMY. I bet he is smiling for pulling that one over on me it very well makes since why he had me site in his rifles lol. ?ÿBut if you would have not said anything i would have never ever doubted it. But American surveyor magazine had an article about him and stated his time with ngs then army then ngs or usc&gs. When I get to the pearly gates I will have to get him back for that one. ?ÿ
@john-nolton what was your MOS. Your service dates coincide with my step dads time he was at headquarters Marine Corps during the end of Vietnam.?ÿ
@frozennorth?ÿ Charlie was a great story teller!
@olemanriver?ÿ Don't feel to bad; That was just Charlie.
@olemanriver?ÿ ?ÿ0848 but sometime just before I got out in Feb. 1970, they changed it to 0844.?ÿ My second MOS was 5711
@john-nolton oh i don??t. Yes he could shuck the corn clean down to the cob (southern for story teller). He sure could. When they would all come out to Corbin for camp fires and drinks. He was always in the middle of a great story.?ÿ
@john-nolton Artillery. ?ÿI was an 0261. I can??t remember but they combined the geodetic surveying and Cartography/gis prior to me coming in i think the geodetic surveying was a 14xx number. Then we also had the artillery surveyors. But all those good ole days are behind me now. ?ÿNow I look forward to following old surveys deeds plats etc. just have not found the right company yet so i can do more of them. Lots of companies staking curb n gutter etc. ?ÿtopos. Well Semper Fi. If you ever out this way give a shout. I will buy the first round.?ÿ
It??s interesting that there??s calibration baselines for checking total station distances, while many surveyors rely heavily on RTK (VRS/RTN even which has more error than local base RTK), where with RTK you can measure two points , then measure those points an hour later and observe a different distance between them compared to the first observation. Basically RTK (VRS is network RTK and has more error than local base RTK) is a variable distance measuring device. ????
Oh my. "...more error..." This has been discussed often here, probably more like beat to death.?ÿ
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Is a calibrated steel tape more precise over short distances than an EDM? Could be.
Is an EDM more precise over certain distances than a steel tape? Could be.
Are GNSS observations more precise than EDM or steel tapes at some distances (between points). Could be.
Are any of those tools more accurate than any other tool you might use? Depends.?ÿ
No, RTK/VRS/RTN/Static, etc does not have "more error" than whatever. No, VRS or Network RTK does not necessarily have "more error" than a standalone base.?ÿ?ÿ
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Is a calibrated steel tape more precise over short distances than an EDM? Could be.
Is an EDM more precise over certain distances than a steel tape? Could be.
Are GNSS observations more precise than EDM or steel tapes at some distances (between points). Could be.
Are any of those tools more accurate than any other tool you might use? Depends.?ÿ
No, RTK/VRS/RTN/Static, etc does not have "more error" than whatever. No, VRS or Network RTK does not necessarily have "more error" than a standalone base.?ÿ?ÿ
Hear, hear. I've worked with some folks that really should have the entirety of this post tattooed on their forehead.
I took my javad to the baseline.?ÿ
Now they know brg and distances between them.
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Just kidding!!
Nate
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Is a calibrated steel tape more precise over short distances than an EDM? Could be.
The precisions of those measurements do not change with distance. The relative accuracy does.
?ÿ
Is a calibrated steel tape more precise over short distances than an EDM? Could be.
A test I took indicated that it indeed is.
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Is a calibrated steel tape more precise over short distances than an EDM? Could be.
The precisions of those measurements do not change with distance. The relative accuracy does.
I said "could be" but still let's explore this, not because @bill93 doesn't know, but because it might be useful for @robertusa
(Honestly, I know I could learn a lot about many things, including measurements, from Bill, as he is a polymath and I am barely a one trick pony.)
For a chain, the theoretical precision may not change, but in practice it does. Perhaps we would then say it is accuracy, but for a 1,000 meter measurement I will argue that an EDM is more precise than using a chain. It MAY also be more accurate, if said EDM is correctly calibrated.
In practice, breaking chain will provide a less precise measurement than an EDM right off the bat (especially for any crew member born after 1980).?ÿ
And of course the way we define an EDM's precision means that it changes over distance. The specs call out: 2mm+1.5 PPM. You start out with 2mm+/- (meaning that if you made many measurements you could expect them all to fall within 2mm of the mean with an overall spread of 4mm from highest to lowest. And, that 2mm is 100% there for any measurement that EDM makes. 2mm from the mean is more relevant to precision at 1 meter than at 1000 meters.
Also, in practice, having to traverse and introducing all those additional setup and sighting errors will reduce the precision of the measurement, much as breaking chain reduces precision.
But perhaps I was imprecise in my choice of words. I will add some clarification: (I wish I had said as to avoid confusion.)
Within the working limits of a single measurement (without breaking chain), the tape will typically exceed the precision of the EDM. Within the working limits of a single set up, an EDM will typically exceed the precision of RTK. That is not "more error". In fact, as we increase the distances between the points we measure, we often find that the tape or an EDM are tools that do not allow measurements as precise or as accurate as those that are possible with RTK/VRS.
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And again, Bill, I do not suppose to teach you this, but perhaps further the discussion and more correctly state what I meant.
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Is a calibrated steel tape more precise over short distances than an EDM? Could be.
A test I took indicated that it indeed is.
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I answered that question as well...but they never tell you which ones you answered incorrectly.