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Weird half a foot bump in GNSS

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dave-karoly
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About mid-morning on 12/18/2017.

We were doing good (or so we thought), got to a control point to do an observed control point (RTK) and it won't initialize.?ÿ Struggle for an hour doing everything trick I can think of, mostly changing radio frequencies.?ÿ Then my partner that day (Jed) says hey why don't we go to that one over there where it was working this morning.?ÿ Get there, still having trouble but showing promise so I changed back to the original frequency and voila danged thing fixes and no more trouble the rest of the day.?ÿ I assume getting behind a ridge blocked whatever was upsetting it.

Two RTK observed control points I did that morning with good statistics don't match anything else in elevation (horizontal is pretty much unaffected).?ÿ I have two static sessions (one hour plus) from the base to a control point, one in the problem period doesn't match the other by about half a foot in vertical, weird.?ÿ It even shows up in OPUS results.

I've never had GNSS just randomly bump vertically like that.?ÿ All heights entered correctly.

Fortunately we have enough redundancy to diagnose what is good and what is bad plus dropping other data (different software) on top of it matches my decisions in TBC.


 
Posted : January 3, 2018 10:23 am
paul-in-pa
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Dave,

I would like to get a look at your two static RINEX files, as there may be something interesting to learn there.

Paul in PA


 
Posted : January 3, 2018 11:23 am
dave-karoly
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Paul, normally I would be glad to transmit the files to you but this project and all of the data is confidential so I can't.?ÿ But I appreciate your offer of assistance.?ÿ I am only talking about it in the most general of terms.


 
Posted : January 3, 2018 11:53 am
holy-cow
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You are in California. ?ÿNuff said.


 
Posted : January 3, 2018 12:28 pm
dave-karoly
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Posted by: holy cow

You are in California. ?ÿNuff said.

Stuff is moving fast for sure, but not that fast.?ÿ And it doesn't jump up a half foot then back down again.?ÿ Usually it jumps up and stays there 😉


 
Posted : January 3, 2018 12:36 pm

paul-in-pa
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There was a magnitude 3 earthquake in CA at noon PST on 12/18/2017. Are your observations before and after that time?

Edit: I see conflicting/supporting information, magnitude 2.6 NE of San Diego just after midnight, magnitude 2.8 east of Redding around 2 PST. I cannot get details on the one in between.

Earthquake causes a slip, bulge results, then bulge relaxes.

I would check the vertical for 12/18/2017 for nearby CORS.

Paul in PA


 
Posted : January 3, 2018 12:47 pm
john-putnam
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Bad HI??ÿ Are you using fixed height tripods?


 
Posted : January 3, 2018 1:51 pm
james-fleming
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Posted : January 3, 2018 1:57 pm
peter-ehlert
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could it be some local scrambling? ... are you near a military base, or something that might be considered part of civil defense?


 
Posted : January 3, 2018 5:41 pm
rj-schneider
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The bad part of those hard to obtain fixes, is the checks on them eat up the same amount of time, if it even fixes again.


 
Posted : January 3, 2018 7:41 pm