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Access Question - Reset RTK

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(@bstrand)
Posts: 1665
Mapper of Things Member
Topic starter
 

I saw this (RTK reset) mentioned in the integrated surveying thread the other day and it reminded me of a question I had.

So when I set a control point I typically shoot it once for 1-2 minutes, dump the rod, rotate the rod 180 and shoot it again for 1-2 minutes and average.  I was informed that "dumping the rod" is the old school way of doing it, and the right way to reacquire the satellites is by reset RTK or reset SV tracking.  What I'm wondering is what the difference is between these settings?  I've been using reset RTK between my shots lately but I wonder is reset SV tracking is better for some reason.

A Trimble page I found regarding this isn't particularly helpful, imo.  RTK initialization (trimblegeospatial.com)

 
Posted : December 1, 2022 7:56 am
(@350rocketmike)
Posts: 960
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To add to your question...when I reset rtk by way of menu>measure>rtk initialization>reset rtk (because the reset rtk is removed from the satellites screen if e- bubble is disabled) it seems to regain a full lock with good numbers almost instantly, despite me seeing it go auton for a split second. I'm used to having to wait at least a few seconds before I can start shooting again, so it makes me wonder if resetting it in this menu, with e bubble disabled is actually doing the same full reset, as what I was doing before (or covering the receiver/dumping the rod) would do, or if it could make any difference at all. 

 
Posted : December 1, 2022 8:44 am
Jitterboogie
(@jitterboogie)
Posts: 3918
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this is the new way.

 

dumping the antenna like we used to do is old school old tech.

anyone promoting that old way with the new gear isn't doing it right.

if you don't believe the software and the hardware work together then put down the GPS and grab the transits the chains and the tapes and get back to work.

 

Get off off my lawn...

 
Posted : December 1, 2022 9:11 am

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(@olemanriver)
Posts: 1021
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Ok let me splainit fur ya. In the old day we turned receiver upside down to force it to reinitialize. This only ck’s the last init to the new init. In technical terms interger ambiguity resolution has been solved twice and they seem to ck with each other. Also in the old day we would set the elevation mask so that no satellites could be tracked. This would clear all locked satellite data and once we dropped it back to 15 degrees it would have to re compute everything and intilazation. Now if you reset initial rtk its same as dumping. If you re set sv tracking it has to rebaquire all svs then it can re init. The latter should theoretically take a smidgen longer. But give you better assurance. But these things track and lock so fast these days we can barely see it. 

now shooting a point same point withen less than a half hour of its self is only given you a warm fuzzy you did not have a bad initialization. It can happen but it is less likely these days vs the old days. If you want to average to have a better position more accurate.  Then you should depending if its base and rover or network solutions allow an hour to pass by. 4 hours gives you a totally new constellation period. 2 hours a partial new satellites coming in old going out. 1 hour just allows for the change in geometry a little bit some new yes .  Now that is gps only i am referring to. In wide open and say base and rober 1 hour is sufficient most of the time. NGS RTK guidelines By William Henning addresses this very topic it is for older equipment but is a great way to base the why you are doing what you are doing is and how to achieve X accuracy etc. there are 2 version of that document. I believe the latest was dated 2014.  

in a hostile environment I would be pushing for the 4 hours gap . I would depend on site conditions shoot a point re set rtk init shoot again  come back 4 hrs later do same  in hostile  this gives me the ability to have a new constellation and ck for a bad initialization. If the 4 hour gap shots are not usually withen the same few hundreths of your back to back spreads. But if you want to see something that helps you understand. Do a shot every hour for 24 hours. On same point. Good sky. If you then average all and compare to the same ever two and every 4 you will even though the deltas are further a part be closer to truth. If my old brain kicks in there is a study similar to this out there  . 

 

 
Posted : December 1, 2022 9:42 am
Said Lot
(@said-lot)
Posts: 85
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Oregon DOT put out a recent study that saw no clear increase in horizontal accuracy with repeat observations at a 1, 2, and 3 hr intervals. Vertical was better at 2 hours but vertical did not improve between 2 and 3 hours. 

 
Posted : December 1, 2022 10:06 am
(@350rocketmike)
Posts: 960
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@olemanriver 

Usually I'll be leaving for a different job by 4 hours later. But I could definitely set some control at my house, with averaged points shot once a day, just for experimentation sake. 

I will sometimes try to take a couple of averaged shots and move on to something else nearby then reshoot once I've finished other work. Usually it's only like half an hour but I feel like it's better than nothing. 

 
Posted : December 1, 2022 10:18 am

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Norman Oklahoma
(@norman-oklahoma)
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In the early days of GPS'ing we would do something called "mission planning", which included "site charting" to insure that we could pick up 5 satellites at a given location and time. It wasn't always a given, not by a long shot. Even when you could get 5 they maybe weren't spread out to give you good PDOP. And the software wasn't nearly as capable as todays. So things like "dumping the solution" were wise precautions to take.

Today, with 12-15 satellites at all times even from obstructed sites, and software that constantly acquires redundant integer solutions every second, dumping the solution is a quant relic of a bygone era. 1995 called, they want their data collection work flow back.

I do approve of rotating the rod 180° and remeasuring. It shows that the rod is true and plumb.  But with the advent of tilt sensors that may go away one day soon also. 

 
Posted : December 1, 2022 10:47 am
(@olemanriver)
Posts: 1021
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@said-lot of as that for rtk or static. And was it gps only or all constellations.  I might need to see how it is now. I mean we get 30 plus sats in a solution now. The gps constellation in full force u will never see all of them at one time. So that changes things. But gps only I would say depends. Theres a reason that PPP positions no base only one reciever tracks the length of time it does for a position.

 
Posted : December 1, 2022 11:51 am
(@lukenz)
Posts: 409
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Posted by: @norman-oklahoma

...but with the advent of tilt sensors that may go away one day soon also. 

The 180° check still good for meaning out the runout in pole or worse someone if someone has bent it and kept quiet!

 

 
Posted : December 1, 2022 12:16 pm

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Said Lot
(@said-lot)
Posts: 85
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@olemanriver That was a study based on traditional GNSS survey control and Network RTK solutions on the Oregon reference network. I would guess at least GPS+GLONASS at most stations, additional constellations at the newest.

https://www.oregon.gov/odot/Programs/ResearchDocuments/SPR304-821_UpdatedSurveyStds.pdf

 
Posted : December 1, 2022 1:19 pm
(@olemanriver)
Posts: 1021
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@said-lot thank you for the links. I will read this for sure. It is always good to read multiple studies for sure.

 
Posted : December 1, 2022 1:23 pm
(@olemanriver)
Posts: 1021
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@norman-oklahoma so true. I still do a little planning and give the crews a heads up to what time a  day will be worse.  But also back then when we were not doing static fast static or PPK. We knew of no such thing as OTF on the fly initialazation. We had to get initialized on a known point. I remember when Trimble sent us the upgrade to get a 4800 to do on the fly initialization. Oh man that was better than p nut butter and jelly. Lol. I use to keep goof tees in my pocket so every so often on a big topo I would set me one and right the number down in my shirt pocket field book. So if i lost initialization i could go back and not have to walk so far. I pictured it back then compared to today as back then we walked as if we had a full cup of hot coffee and did not want to spill it with a rover. Now we have an enclosed bottle no spill so we can run lol 😂

 
Posted : December 1, 2022 1:36 pm

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(@robertusa)
Posts: 280
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Reset satellite tracking clears any lingering satellite data and is quicker to do.

 
Posted : December 1, 2022 1:45 pm
(@350rocketmike)
Posts: 960
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@olemanriver 

Unfortunately I don't think our job scheduling issues make mission planning very feasible. The most I see is one crew say to another "our GPS was nfg today, how about yours?"

Walking with the GPS I have a habit of keeping it almost perfectly upright to prevent losing a lock, but I picked up that habit years ago. Same with walking with the prism and trying to keep a lock. 

My occasional helper still doesn't listen to me about holding the prism upright, he throws it over his shoulder and then loses his lock. I keep telling him "it's not the Leica! Lose your lock and it's a lot of screwing around to get it back LOL. 

 
Posted : December 1, 2022 2:37 pm
(@bstrand)
Posts: 1665
Mapper of Things Member
Topic starter
 

@olemanriver

Right, I'm aware of the 4-hour window.  I'm a bit more concerned about the bad initialization because it seems to pop up at the most unexpected times-- like the middle of a wide open potato field.

Reset satellite tracking clears any lingering satellite data and is quicker to do.

Reset RTK goes pretty quickly anyway, probably 3-4 seconds is all.
 
Posted : December 1, 2022 3:25 pm

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