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Things that go wrong with GPS
The BIGGEST thing I see that goes wrong, is ASSUMPTIONS.
My dad using the LOCUS GPS often did the connectivity fail. He still does not get it.
How to do this fail, is set out 3 (or 6) GPS units, simultaneously. Then, collect all data at the same time. Next, move them, one at a time. (all is good)
NEXT DAY do the same, BUT do not re occupy any of the previous day’s points. So, you now have 2 independent sets of data. Interconnectivity fail.
Essentially, repeat the above, until you drive your son to give up….
OK, here is how you do that same thing, with RTK.
Go, set an autonomous base out. Work all day. (don’t set a nail at the base, heck, we are in the space age!)
Go back next day, set base out. Set it near where yesterday’s site was. Maybe within 4-5 feet (Don’t set base nail, heck, we are in the GPS age. NOT NEEDED!)
Go home, and calc it all up.
Go back, and set final corners. Base is now in a 3rd location.
Never understand what happened. Repeat on next job.
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OK, movin on up…..
Set base out. PLACE a nail at that base site!!
Autonomous once again. Work all day. (we in the space age!)
Come home, and SEND THAT BASE TO OPUS! O yeah!
Now, we have a REAL coord at the base.
Return to site, and input the real coord, for this base.
FAIL to modify the coords, generated yesterday. Coords are off by the amount the Autonomous was off.
BUT surveyor is confident. He OPUSed it!
He continues on. keeps on doing this.I am seeing BOTH of the above.
It’s the only explanation I can find.
Nate
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27 Replies
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Nate, I’ve seen the exact (almost) thing, collect data all day, never set a physical monument, don’t know what coordinate system it’s on, no idea how to recreate it, but it was sent to OPUS, so,,,,,,,,,,
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Here is another one.
Go out, set base. Autonomous position. One Point setup. Scale factor, set to ground at the base (combined scale factor). Rotation set to Geodetic at base. NO NAIL. Perform survey. Go home.
Go back, and RESET base on new base point. BUT localize on a monument in the corner of the field.Now… what’s up with this?
It’s actually ok… just bad procedure. We now have a slightly different scale factor, and a slightly different north.
I know a surveyor that does just this.
I think he sort of enjoys leaving those who come behind guessing… yeah, it’s not too bad, IF the base is not alot different….
Gads. Retracing GPS requires finding EVERY hole in the bucket….
Makes me think of a song…
“There’s a hole in the bucket” Harry Belafonte
I’m drawing a plat. Hafta get it done.
I wish I could stay in the woods.
N
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Didn’t the equpment salesman tell him that was how to do it?
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Yeah, maybe. He probably fell into that habit, via, being unable to find his nail, or a cow pulled it out… so he had more work to do in there, and so developed this habit. He does not opus.
N
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It is no wonder that I don’t understand GPS.
All the slang terms that you have used make it impossible for me to understand it.
It is like working with my son, and hearing him say, “Now just spin the angle”.
What? -
For JEFLS.
I’d suggest that you simply go and interview a couple of younger surveyors, who own GPS, and who know what they are doing… (to determine this, ask them to tell you) make sure you interview at least 3 practitioners, who use it every day)
Tell them you are interested in hiring them to do a job. Be up front. Tell them you want to interview them, for a future project.
Then, Put them on hold.
And, wait til you get a pretty good job.
Call your young fella.
And go do it with him.
I cannot figure out a better way to learn. That is what I did. I simply hired somebody that I knew and trusted.
Ran for 2 days. Did not make alot on that survey, but I LEARNED alot.
And, I still am.That’s how I did it.
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Connectivity fail is like traversing to point 20 and 21, packing up, and going home. Then, next day, set up on 24, BS 23, and continue the traverse, WITHOUT every setting up on 21, and backsighting on 20, and shooting to 22. This makes traverse connectivity fail. With GPS it does not COMPLETELY fail, because it can obtain an autonomous point, but that reduces things to the accuracy of an I-phone GPS or a hunters grade GPS.
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What is multipath, Alex?
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Dave Karoly, post: 348576, member: 94 wrote: What is multipath, Alex?
Multipath is error caused by the signals deflecting off objects such as trees or buildings. The GPS calculates position by timing signals sent from satellites and when it reads a deflected signal, the time read is longer than it should have been if it was direct from the satellite, causing the error in calculation of position.
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What is weird is replies by Rich always go to the top just underneath the O.P. out of order, for me at least.
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Dave Karoly, post: 348576, member: 94 wrote: What is multipath, Alex?
Alex, what is “Oh, East is East, and West is West, and never the twain shall meet “?
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But there is neither East nor West, Border, nor Breed, nor Birth,
When Leica & Trimble stand face to face, though they come from the ends of the earth! -
Dave Karoly, post: 348638, member: 94 wrote: What is weird is replies by Rich always go to the top just underneath the O.P. out of order, for me at least.
Me?
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Yeah, you. Why or how do you do that?
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clearcut, post: 348736, member: 297 wrote: Yeah, you. Why or how do you do that?
…….I have no idea…..
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hmm. weird. seems to be somehow related to your use of “tapatalk”.
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Both of your posts are in the top right underneath the O.P.
Some strange glitch in the forum software.
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Dave Karoly, post: 348751, member: 94 wrote: Both of your posts are in the top right underneath the O.P.
Some strange glitch in the forum software.
Is it just this thread or every thread I post in? I noticed it one time today but never before
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Dave Karoly, post: 348751, member: 94 wrote: Both of your posts are in the top right underneath the O.P.
Some strange glitch in the forum software.
I just updated the app. Hopefully this will fix it as it just started happening. Please let me know if it continues and if so I’ll stop using the app.
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Rich., post: 348754, member: 10450 wrote: I just updated the app. Hopefully this will fix it as it just started happening. Please let me know if it continues and if so I’ll stop using the app.
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Yep both of the new ones are at the top.
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