@jitterboogie?ÿ Taking it to the extreme often provides the answer. If you are measuring between two points about a half-inch apart I'll take a pocket tape or scale any day. If you are measuring across the Grand Canyon it will be RTK hands down.
I contacted the NGS I&M Branch about the 100 foot monument and was told they were no longer supported due to a lack of interest by surveyors.
?ÿ
This is all great, and we should be concerned enough to make sure that our equipment is well tuned and working properly.?ÿ But I don't think our measurements and/or techniques are what might get us into real trouble
Hi Everyone, don't forget that if you have relevant info to share about an NGS CBL that may help others recover it or be better prepared to use it, or not use it... please let us know.
Contact the CBL Program team via: [email protected]
Or reach out to the Regional Geodetic Advisor via phone or email and he or she can ensure your information gets delivered to the CBL team: https://geodesy.noaa.gov/ADVISORS/
We are rarely able to do preventative site visits, so any information on access, vegetative growth, safety precautions, etc., could help the next person know what they'd be up against.?ÿ There's some nice CBLs out there, but there's also a lot that are nearly unusable or downright unusable.
Oh, and @RobertUSA myself and at least one other advisor have been mumbling internally that we ought to provide a "GNSS CBL" of sorts, that would allow users to validate their entire system: from antenna to post-processing to coordinate conversions.?ÿ ?ÿIt's mostly just a thought experiment at this point, but some personnel have at least agreed it would be a valuable service, and could potentially be a part of some future version of OPUS.
@jalbrz?ÿ
Posted previously on this thread was a link to the Canadian approach.?ÿ
Have you seen this: https://www.ijser.org/researchpaper/A-convenient-procedure-for-the-calibration-and-check-of-GNSS-systems-by-using-the-relative-static-positioning-method.pdf
i am wary of the comprehensive approach while accepting that the best test of a GNSS is its ability to meet a standard. I do not know how those creating GNSS processing software validate its performance. I suspect that they do not include all the modeling performed by GAMIT, GIPSY, Bernese and PAGE-NT. Nor do they likely follow the IERS Conventions.
This idea was discussed by folks at NGS like Dr Mader and Mr Hilla. I do not know whether any of it was documented.
My 0.02?ª
@jalbrz?ÿ ?ÿI was about ready to post some information and GeeOddMike beat me to it. Look at the paper he poster under the?ÿAbstract and you will see ISO 17123-8
Everyone should read this. Also?ÿGIM International?ÿ?ÿhas a 2 page?ÿARTICLE?ÿon "A Modern Calibration Bench: Calibrating Survey Instruments
One last remark; you said "Oh, and @RobertUSA myself and at least one other advisor have been mumbling internally that we ought to provide a "GNSS CBL" of sorts, that would..."?ÿ?ÿWell you are so young you do not remember that in the early days just something like this did exist. See "Report on Test and Demonstration of Macrometer Model V-1000 Interferometric Surveyor" this was the first commercial geodetic GPS unit on the market. This report was from the OLD FGCC (I think it's now FGSC) done in May 1983.
The test network was done in the Washington D.C. area. "The distances were from 186 meters to 1.3 km for short base lines and 8.7 to 42.1 km for medium length base lines"
This might help you in your present day endeavor.
JOHN NOLTON
PS?ÿ ISO 17123-8:2015 Part 8 is GNSS field measurement systems in real-time kinematic (RTK).
In my above post I have 2 letters turned around It's?ÿNOT?ÿ FGSC;?ÿ It's FGCS
Federal
Geodetic
Control
Subcommittee
Most of the FGCS reports (some are archived) are available here:
https://www.ngs.noaa.gov/FGCS/instruments/reports/
The program ran from 1983 to 2001. The V-1000 report is archived.?ÿ
The earliest report is:
Early days of GPS with an incomplete constellation, poor orbit accuracy, no phase models, no fixed tripods, and NAD83 not yet implemented.
These are the instruments tested:
I frequent a CBL about an hour from me a few times a year prior to deformation surveys. Its setup a long the side of a runway at a small airport. I call the airport manager a few days ahead of time to get a day of good weather and low activity.?ÿ
I like overcast days, but I still take a popup tent to shade the instrument. I have a set of high precision Leica prisms that I run through the paces on every station, forward and backwards. I observe my temperature and pressure at the site with a handheld weather station before each prism set. I compile all of this information using calibrat. The instruments are serviced annually but are also run through the Leica calibration routine before a CBL visit if it hasn??t just returned from the service center.?ÿ
@geeoddmike The only problem with building a toolset based on the method described in that paper is... no one will use it!?ÿ
Why? The amount of field time, like a full check using one of EDMI CBLs, is seen to most as unwarranted or not worth the investment.
Even though you feel the need to poke fun at my age, I will respectfully refrain from making any old age jokes.?ÿ Suffice to say that I, nor many young people, are ignorant to everything that occurred before we entered our professions/careers.?ÿ Is this what people mean when they say they are encouraging younger people to enter this profession??ÿ Hit 'em with below-the-belt jabs when they step in to simply put information closer to people's fingertips?
FYI, I've got a copy of FGCC-IS-83-2 sitting on the floor next to my chair right now, photo attached.?ÿ
And what I'd like to see are bunch of mini networks, not one set of 8 stations in/around DC.?ÿ The whole point of this would be a method of system verification for our constituents; an effective, efficient way of verifying hardware, software, methods, even non-NSRS networks.?ÿ But with modernization efforts currently undergoing some re-prioritizing, I don't foresee an OPUS-based "GNSS CBL" anywhere in the near future.
@bushaxe Hey, good to hear you're out there keeping' your gear in tip top shape!?ÿ You ever look at our replacement for CALIBRAT??ÿ It's totally different, but named CALIBRATE.?ÿ It takes more setup, but it's pretty slick.?ÿ Drop me a line if you ever wnat to look into it, I talked to Mack and his folks at LRH about it, but they didn't get to use it last year as I discovered a problem with it that prior week!?ÿ It has been fixed/updated now, here's a link: https://geodesy.noaa.gov/PC_PROD/CALIBRATE/#
@jalbrz?ÿ ?ÿSorry to hurt your feelings. It won't happen again; I assure you of that.
Hurt feelings, no. But it is annoying hearing that sort of comment from my elder mentors, often the same folks hoping to preserve & grow this profession.?ÿ I guarantee that it's run off some interested and capable candidates... but not me.
@bushaxe Hey, good to hear you're out there keeping' your gear in tip top shape!?ÿ You ever look at our replacement for CALIBRAT??ÿ It's totally different, but named CALIBRATE.?ÿ It takes more setup, but it's pretty slick.?ÿ Drop me a line if you ever wnat to look into it, I talked to Mack and his folks at LRH about it, but they didn't get to use it last year as I discovered a problem with it that prior week!?ÿ It has been fixed/updated now, here's a link: https://geodesy.noaa.gov/PC_PROD/CALIBRATE/#
Good to know. Thanks
just downloaded Calibrate.exe. how do i get data to the .tra file it needs. i have baseline data stored for another software. not sure how to get it into calibrate.
@jalbrz got any instructions for use? i have baseline data but cant figure out how it get calibrate to read it.
I don’t know whether Jalbrz monitors this site. His contact information is found on this webpage:
https://geodesy.noaa.gov/ADVISORS/index.shtml#Great%20Lakes
He is the NGS Advisor to the Appalachian region.