What the heck is a "here" setup?
An autonomous position determined by your receiver in the field. Generally used just as a starting coordinate so your vectors have something to be referenced to. Autonomous positions are at best +- feet from ??processed? positions.?ÿ
I only use the ??here? setup if I can??t get enough service to use VRS. Usually log static in the background while the base is setup(at least 2hrs) while I??m working in case we want to process it later. Whether you are doing a ??here? setup logging static then process it or you VRS a point and setup the base and rover, the results should be similar. Although I think the processed static observation would be more precise.?ÿ
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Currently, we do one, fifteen-minute session.
I never saw much difference after a 3 minute observation. If I need more precision I think I would be better off running a static session and processing it. I dunno, I guess everyone has there own way. Haha
The four-hour separation window was NGS guidance, tailored for single-constellation observations. When running full constellation, that four-hour window just doesn't apply any more, as orbital periods vary from ~11hr for GLO to ~14hr for GAL.
As for that 15-minute observation....it's a waste of time unless you're also logging raw data and post-processing the static vector to include in the adjustment. NRTK results hit a point of diminishing returns?ÿ (graph of outliers completely flattens out) within 2 minutes for horizontal and 3 minutes for height. That study was back in ~2010 and only used GPS + GLO if I remember correctly.
With quality modern equipment, the chance of a "bad fix" is extremely low, so I'm not really too concerned about doing more than two occupations unless it's for high-precision work, or there is a serious discrepancy between the two observations. That needs to be checked in the field. (We also do a lot of total station work tying those points together, otherwise I might be more inclined to do three as a default.) A huge part of the problems we see stem from laziness i.e., "just shoot it twice" without clarifying that the standard deviations of the average position should be within tolerance.
If we're going to go setting control in tricky areas, then yeah, we need to change tactics. Mindlessly doing things the exact same way every time is just asking for trouble.
My preference is to have crews tie everything in the morning, go take care of the topo, total station work, etc., then come back and tie it all again at the end of the day before going home. More efficient than trying to keep track of when you last tied something, and splits the day into defined tasks.
If I have a base, I'm not even going to bother with getting a VRS position for the base location, unless I have some very tricky monuments/control already in a defined system that I need to search for. Just post-process the statics data against NGS CORS or the RTN stations themselves.
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I'm with @oldpacer in considering the biggest problem as just tossing VRS coordinates into a CAD drawing directly from a CSV export and treating them as gospel.
Post-process the data. Get redundant observations and adjust them along with the total station and level data. It's pretty obvious right there in the field if your data are not looking good, but post-processing tells the true story of the data.
VRS is a tool like anything else. Understand it, build checks into your workflow, and don't abuse it.
I can't add anything to the discussion on best practices, but I'd like to ask if you guys have some sources (books, websites, courses?) for learning about the VRS and how it works??ÿ Are there any sources that can help me understand more about it and learn those best practices??ÿ The company I work for doesn't use it (yet) but if/when we do I'd really like to have a better understanding.?ÿ?ÿ
@olemanriver I've not followed behind someone doing that.?ÿ But a friend sent me data, where he was following behind someone else, to look at once.?ÿ The other person either did what you just described or simply picked up and put the base in a new place, stored a new here location and continued on.?ÿ Sections worked with each other, but there were about 3 distinct shifts of just a few feet.
@jon-payne yep it is a nightmare to figure out. Especially when the man who did it said just least squares it and fix it lol.
@rover83 i tend to agree on the 4 hour window if the network vrs and your rover are full constellation. ?ÿIt goes back the 4 hours to static days before rtk. ?ÿIt has to do with gps only in constellation change. But with all these birds it is probably not necessary. The single base guidlines for rtk depending on class you want and if you move your base gps only I believe cut it down to 2 hours. ?ÿI am trying to remember the exact name i have 2 different ones dat wise. Is it rtk guidelines for classical by William Henning ngs. Something like that. ?ÿ
for vrs thats a Trimble thing only. There is several configuration on how you can set it up so the best place to learn what that specific network is doing should be from the provider. Different mount points and how it is running are not equal. Geo++ is another one many ways to customize solutions to specific recievers and or areas. Not all are equal. I know those pretty well operated both platforms at same time. Topnet and leica version alhave there pros and cons. I used a leica smartnet some but it was in the early stages of development so was truly single base no ionosphere models at that time it just pushed you to closest base however far. We had multiple set ups in each platform vrs Trimble and geo++ even had a Chinese made version for a bit as we tested cannot remember the name. But based on our customers equipment and what they wanted to achieve and area we gave them the down lo on each and pros and cons of each different mounting points. What to watch for and what procedures checks that worked the best on each configuration. ?ÿI had spent hours and hours doing test all around and so had my partner. ?ÿWe had customers doing the same. That was a ways back so i am sure some things have changed a bit. In both platforms. Geo++ is what is used by the group to move wgs84 closer to itrf etc etc and it is used also for the orbits and getting data all around. Gs ngs does there own orbits. Nga does the orbits for gps. And wgs84 reference frame and global geoid model like ngs does for conus. But globally. ?ÿ
If I have a base, I'm not even going to bother with getting a VRS position for the base location, unless I have some very tricky monuments/control already in a defined system that I need to search for. Just post-process the statics data against NGS CORS or the RTN stations themselves.
I think the idea of a VRS point to set up a base on is to eliminate the need to process static for jobs that need not be as precise or are relative only to themselves such as boundary work.?ÿ
With quality modern equipment, the chance of a "bad fix" is extremely low, so I'm not really too concerned about doing more than two occupations unless it's for high-precision work, or there is a serious discrepancy between the two observations. That needs to be checked in the field. (We also do a lot of total station work tying those points together, otherwise I might be more inclined to do three as a default.) A huge part of the problems we see stem from laziness i.e., "just shoot it twice" without clarifying that the standard deviations of the average position should be within tolerance.
If we're going to go setting control in tricky areas, then yeah, we need to change tactics. Mindlessly doing things the exact same way every time is just asking for trouble.
My preference is to have crews tie everything in the morning, go take care of the topo, total station work, etc., then come back and tie it all again at the end of the day before going home. More efficient than trying to keep track of when you last tied something, and splits the day into defined tasks.
If I??m concerned with the occasional bad fix then I would probably reset the satellites and start a new observation and check the deltas report. It would depend on how close it is whether I overwrite, average or leave it as is.
Regardless of what time of day I set my first control point, if I set the base on that point, every other point set thereafter is relative to that point. Or so I thought. Then again usually the first thing I do on a new site is to set all my control anyhow (which I usually in the morning).?ÿ
Inside GNSS does a pretty good job.
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@gschrock manages our state network WSRN you might find what you're looking for there.
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good luck!
Is it rtk guidelines for classical by William Henning ngs.
@curiouser in our area it is keynet. If that is what you are using Trimble equipment. ?ÿIf using leica then its a different network and not vrs but the smartnet. I can send you the link just email my personal email if you still have it or remind me tomorrow. ?ÿMost Trimble users are on keynet. Its better up in northern va vs south and south west and central va. Fyi. Not as dense so I don??t use it as much not very repeatable in some areas. You can call me as well i can explain the vrs much easier than i can type it. If you want some good rtk books in general i will get you some. Before learning vrs learn the basics of gps and basic rtk base and rover first. Then the vrs is much easier to learn. I will ask the wife but I believe ngs has some online videos of bill Henning presentation still i did one base and rover and also a network rtk but it focused more on network operators and tying it to nsrs more than anything else. It is one of the ways i met my wife lol that and geodetic leveling and such. If they ever get back open you should go out to the training center. Take some field folks see the edm baseline the absolute antenna calibration and relative antenna calibration station. Some neat stuff and very laid back. Good people working there. I operated the largest privately owned real time network with the current owner as a partner up until the big recession. If its Trimble vrs i am not that far gone on how it works and things to look out for. Alan dragoo I believe did most of the adjustments on keynet if I heard correctly. Very very smart man. He is about as good as it gets as well in least squares. Truly did an awesome class once. He was at the convention but was not teaching. Great man contributes greatly over the years to the profession.
@field-dog yep there are two different prints i think the 2014 one you sent the link was the latest. I will ck my spreadsheet tomorrow to confirm. I set up a spreadsheet to hyperlink to different publications from ngs and various sources. There should be an online class that you can watch as well on training site if not email my wife and ask why she doesn??t have it posted lol. But don??t say I told you. I stay in enough trouble myself with her. It??s probably under past training classes around 2011 or 2014 time frame roughly. Mr Henning gave a power point on that document information.
@dougie ?ÿmr schrock is very smart man very smart. He knows his network stuff. He along with my previous partner were some of the first to implement such things. To bad some abuse the tool but he is one I would hang my hat on as knowing.
online videos of bill Henning
@field-dog I will have to watch those. Those are not the ones i was remembering but i am sure they are great. On ngs website when he was employed by NGS he did some. Those might be it who knows i will have to check out. I am just on my phone so everything is small looking. The wife and kids just got back home so it will have to be another day. So many resources out there now days. Videos documents on internet. ?ÿOne thing I learned is no matter who it is no matter how much you like them. Go find another authors and get there opinion. I have been in a room literally physically with 20 plus people who all have phds. And hardly none would agree sometimes. I have seen them debate a parentheses in a formula for a while. ?ÿSo study for your self use good judgment look for more information on same subject. Look for peer review documents. None of us are perfect any body can mis speak or mis spell or mis quote. ?ÿWhat comes out of our mouth or fingers might not be heard as intended. Not to say they are wrong or bad just we are all humans and can make mistakes.
Sending a crew out with them not aware control has already been set
They assume VRS means they are on SPCS same as the last guy and they??re good to go I guess.?ÿPerhaps they??re overestimating its abilities?
Why are they making that assumption?
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@tommy-young ?ÿI believe a lot of people assume that just using gps means they are on state plane. Heck for every GIS tech that states i want gps coordinates i here almost as many surveyors say that same thing. Me not being a master of words I cringe at how some make statements like just get me some gps coordinates and we are good. If we in our different areas are required to place say at-least 2 corners on state plane which is what is required in a couple counties around here. I believe the guidelines or standards need to be clearer in this regard. ?ÿI have asked several LS what accuracy does the state plane coordinates need to be . Some say it doesn??t matter scale them from a map. Google earth etc. ?ÿI know of 10 boundaries right now that are signed sealed recorded that are a half foot delta in north and east or way more. ?ÿFrom being in the correct location on the datum and projection. I will not even go to the fact the reason of this of using a grid ground scale not documented. ?ÿNow the boundaries are all good relative no boundary issues that i could see. Just grid statement and two required northing and easting on thos random corners. ?ÿThe best surveyor I followed in regards to having a datum statement and coordinates was very well documented. He was on grid bearings based on the datum epoch and zone. He had all meta data. A note stating the two corners were on spc datum all but acreage and distance were all ground. So if you inverse the two monuments coordinates they were grid but the plated distance was ground it was easy to follow I could repeat what he had done without head scratching. Trying to figure some out is not easy. ?ÿHis coordinator were well within any standards so when I jumped out and fired up the rover i hit very close not feet not half a foot but less than a tenth. Became tighter than that after i set up did some static and tied everything down with rtk robot and static did adjustment etc. ?ÿit made a quick find of a couple corners to get started from . ?ÿI don??t know how the best way to do all of this is. I have often thought at point of commencement or pob and one other to add a little more info for surveyors in future to retrace. It is just another aid is all. Not necessary to have but if you are going to then I think it shows be done with quality and care.
Why are they making that assumption?
Probably because their PM/PLS told them that it was all the same, because they had no clue either...
I have had licensees ask me what geoid the RTN uses, or whether it was "broadcasting NAVD88 or NGVD29", or which state plane zone it was in, or whether it was "in grid or ground".
If leadership broadcasts to employees that it's OK to be ignorant, they're not going to ask too many questions either.