Can Float give accurate results with Post Processing?

I have a pair of RS2 units that I typically set up with one as a Base and one as a Rover. I use single solution to find the Base location. I then use this system to either do stake out for projects or to map underground utilities. Accuracy of +/- 3" is adequate. I usually have control points that I’m able to reference and then correct my data in CAD when mapping, or I make a second trip if I’m going to stake out after I’ve determined the correct coordinates for a fixed base position using the known points.

Often the terrain and overhead power lines make obtaining Fix positions difficult or even impossible. My first question is, with this setup can I gather points with a float solution and then use Post Processing to correct the data to a more accurate position? If this is not a viable solution, the next step that I see is going to a subscription service and use NTRIP. Since I only have to do this once or twice a month at most I am hoping not to have to use a service.

Thanks in advance for any help and suggestions.

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Why not ? Just make sure you log adequate time for each station in order for the baseline to converge. I’m assuming you will be PP with your base receiver.

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Not sure I understand about plenty of time for baseline to converge. Base would typically be set up for an hour or two during the process. I then use the survey function to collect points, allowing about 30 to 40 seconds per point. How exactly would one correlate the survey points to the PP output? I’m inexperienced at this and I see literally thousands of points from the PP process. Do you just have to draw a circle around the heavy groupings and use that as a means of averaging?

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No, usually when I’m doing a static session I collect data for every point separately. To clarify, I don’t have one continuous file for all points. I have a separate file for each of the GCP’s. Also you need to use a local base for the rover. Depending on the baseline length, I would recommend a minimum of 4-5 minutes per station. If you’re PP against a CORS that is several kilometers away, you would need at least 15 minutes per point. Others here would recommend less, however I always dislike revisiting a site because there’s not enough observation time for the GCP’s. Better safe with long observation times than revisiting the site because of being impatient. Usually I’m using a state RTN service with VRS capabilities. I also have a base running in case of cellular loss. That way I can PP my survey points or GCP’s with the local base onsite having short baselines. Short baselines are your friend. Usually, my baselines are less than 2-3 km and occupation times are at least 5 minutes per station. Most of the time 10 minutes or more if in high multi-path areas.

What he :point_up_2: said
Also just want to tip you about Emlid studio.
Its still in Beta https://docs.emlid.com/reachrs2/tutorials/post-processing-workflow/working-with-emlid-studio/introduction-to-emlid-studio

As stated before, use enough time at each point.

I also noticed using two devices of the same kind might outperform when it gets to challenging areas. Two Reach units of the same kind and firmware will fill each others “shoes” completely ", a VRS or network might not. This is usually not a problem.
Where i have seen base-rover shine over a paid service, is where the cellular coverage is poor or working down in man holes or in between buildings.

You must work in very flat areas. My longest baseline is no more than 1/4 to 1/2 mile. Too many trees, hills and twists in the roads. My work is always roadside.

When you say GCP do you mean ground control point?

Thanks.

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Thank you, I will look into the Studio product.

Hi Frank,

Sometimes, it’s indeed possible to get a Fix in PPK while you have a Float only in RTK. For example, you can play with settings while processing data in PPK and get a better result. However, we can’t be 100% sure since it depends on data quality.

Also, using NTRIP can hardly help in this case. Most likely, the NTRIP reference station is placed under an open sky view. However, it doesn’t matter if the rover can’t track enough satellites.

To get coordinates for separate points in PPK, you can use our new Stop&Go feature in Emlid Studio software. You can also learn more about the work with Stop&Go feature from this article.

Just want to add that Emlid Studio is now in beta, which means it is still in development. Don’t hesitate to share your feedback.

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I’m mostly surveying property boundaries and sometimes ground control points for photogrammetrists. I mostly use our RTN service for location but I usually have another receiver on site just logging data. It’s good to have a backup method if RTN or cellular service goes down. I’m using either my M2’s or RS2 for logging. Neither of these like multi-path and 90% of the time I’m in the woods using my JAVAD Victor LS as the RTN rover.

I wish I had surveying background, it would help with understanding the lingo, limitations and proper procedures. I bought the RS2 units thinking that I could get the same type of capabilities that a road construction forman had using his Trimble unit with a cellular connection and all their support software. While I’m not disappointed with what I’ve been able to do with the RS2, my lack of formal training and the more simple nature of the EMLID ecosystem has proven frustrating at times. As with anything, there’s no replacement for knowledge, experience and the best equipment you can buy. Good thing my results arent critical.

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Thanks Julia, I’ll look into the article and Stop & Go.

I notice that the Survey function in ReachView 3 is quite different from version 2. Is there a tutorial on the new version somewhere? I looked yesterday and was not able to find one.

Try and get to know some of those that use UAV’s or those in the surveying profession and ask for advice. Buy them lunch or six pack of beer. The surveying profession and processes are not that hard, although I’ve been surveying since I was 13-14 years old and have been licensed for almost 40 years. I have had people approach me on the side of a road asking questions and wanting to learn the surveying profession, tools and methodology. In fact, we’ve trained 3 individuals that have become licensed down through the years. Talk to some local surveyors over lunch… You’d be surprised how interested they are in helping people get into the profession, especially young people. It takes a special person to go into surveying. Someone who likes to learn and enjoys the outdoors. I’m 63 years young and learning new software or hardware keeps me going in this profession. Although I’m not able to get in the field like I use to due to a back injury, I really enjoy talking and explaining our processes to people who are interested in this profession. As with anything else, it can get old pretty fast unless there is a basic yearning to learn new things and to help others who also want to learn.

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Can you hire me? :stuck_out_tongue: sounds like you have some good and solid company values there!

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I called the surveyor that I’ve used twice on my property when I first was playing with my units to get a digital plat from him. As I discussed what I was doing he just bemaoned that road work has been taken from the surveyors and the Contractors are doing it with GPS units and couldn’t help me with the electronic copy. I then stopped and tried to talk to a surveyor working across the street and he was grumpy as hell. Saw his truck and it turned out to be the same company. I’d never met him in person until that day. Kind of soured me to the whole thing, but I’ll try again. I to am 63 and in a second career that allow me to learn new things and it is a great thing. If you were close by I’d be happy to buy lunch and a couple of beers.

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My recommendation would be to observe at least 20 minutes per point, preferably 40 minutes. You need to have enough to ensure a solution where 4-5 minutes in my opinion isn’t enough.

Float can be up to half a meter off, especially in height.

If possible, do the survey when there are no leaves on the trees, leaves will kill your signal even further!

I can also recommend multiple bases when processing, and then processing them together in Least Square adjustment network, using i.e. EzSurv. But time and money wise you are approaching a Total station task.
Check this project I did in quite challenging conditions: Using 4 x RS2's for precise results in challenging environment

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I am not sure which state you are in Bryan. If I get there I would be happy to buy you dinner and some drinks. Same applies to Chascoadmin, PotatoFarmer and several others.

I do not use any post processing but have enjoyed learning the process. I am 53 and in a solid stable career so not looking to change but love learning and teaching others.

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That’s why I’ve always tried to impress everyone on short baselines from day one ! 2-3 km baselines with closed loops and 4-5 minutes rover observation times are more than enough. This is performing static only. Two base receivers and a rover (closed loops) doing static observations in clear sky environments is more than enough with a good post processing engine, whether it’s EZSurv, RTKLIB, TBC or Javad Justin 3.

As I’ve said before, how can you really know what the RTK accuracy is without a closed loop ? At the cost of Emlid’s products, two M2’s onsite and RS2 rover doing static observations ( all three doing static) on short baselines is a very cost effective solution.

Frank, we’re all here to help each other on this forum. Even an old fart like me has learned a lot from super geniuses like wizprod, TB_RTK, jo-drain-sol, chascoadmin and others !

Emlid has a super support team and a good product.
Just reach out to any of us if you need help.

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Yeah, but here we are talking about an environment that under RTK-conditions gives float. Hence my advice to extent the observation period to something much longer.

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Bryan,

Yes, you and many others on the forum have been invaluable. I’m just far behind the curve and I hate to keep bugging you guys with questions that any basic surveyor would know.

I don’t mind bothering the Russian girls at all though. :grinning:

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