Reach RS+

Hi,

Can any one let me know how to use Reach RS+ for taking the static GCP’s in the field …I am not interested in RTK mode …

Your valuable suggestion shall be much appreciated.

Regards

Rahul Jain

Did you read the Emlid documentation on the subject ?

https://docs.emlid.com/reach/common/tutorials/gps-post-processing/

What kind of data collector equipment will you be using? And what grades will you be using (ellipsoid/Geoid/surface)? There are a couple of lengthy discussions on these.

Yeah, just 1 or 2. ; ) I for one will be using a Radio Shack TRaSh-80 with a power inverter, die hard car battery in a grocery cart.

I am using ellipsoid only at the moment,

My question is simple how do I save the static log for each Point on Emlid reach rover as the base is already setup…and taking the logs ?

You’d probably want a stop-and-go flow for that, where you collect base and rover log for entire duration of your survey.
I would then use the Survey tab to make start and stop times (just like when using RTK), and then use these time stamps in RTKplot, after using RTKpost to compute the whole rover log in the kinematic mode.

Yes you are right, But when i tried with the same way and during calculation in RTKLIB the values from the rover is zero only…though the values from Survey are are ok…but it seems that it was in RTK mode …

What did you use for base input?
Did you use any clocks and orbits?

Maybe you could try turning the logging on and off for each point? I have done this before when I had a hard time maintaining fix. I just noted the approximate time of each point and it made it easy to know which part of the logs was that shot.

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Hi Rahul,

Did you manage to resolve it? May I ask you to share your raw logs?

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The Reach or Reach RTK units are not really good for gathering multiple static gcp points in the field. They are fine if you have the time to sit for 10 mins on each point, but that is not viable if for instance you need to collect 10-20 gcps for a UAV mapping project. What is needed is a function for doing a traditional Stop-and-Go survey, which would allow for short collects on each point (e.g. 30 secs). My research with the Reach units shows that generally 10 minutes must be spent on each point to get a fixed solution in post processing. There are some work-arounds, timing marks and some external software apps, that some folks have come up with for doing shorter collects, but IMO these solutions are only viable for experimenting, not for doing actual work.

THE BIG GLARING HOLE IN THE EMLID WORLD IS THE UNWILLINGNESS TO ADD STOP-AND-GO TO REACHVIEW. IT IS A MASSIVE HOLE.

For my UAV work I use an Reach unit on my drone, but for collecting gcps I use old survey grade gps units (Promark 3s) that have a beautiful and simple Stop-and-Go survey mode. I just used these units to collect 24 gcps (30 secs on each point) for mapping an airport and surrounding area at super high accuracy.

We use the Reach units in RTK mode for mapping gravel pits, but other than that, in the world where I live, everything else is Stop-and-Go.

I just finished a report for a govenment agency, here in Canada, and I could not recommend the Reach units, as much as I wanted to, because of the absence of Stop-and-Go. RTK is not a viable option for the majority of field work we do in the north.

In the DGPS world there is a gigantic hole for an affordable GPS that will do Stop-and-Go surveys. Until a few years ago there were affordable units (Thales Promark 3s ~$2000) that had that functionality, but they seem to have gone out of business. Now there is nothing out there that is affordable.

So EMLID - are you listening!!?? - there is a GAPING hole in the GPS world that needs to be filled that would be to you immense advantage. Fill it!! Add a tab to you ReachView app for non-RTK surveys (post processing) and have three options on it: static, stop-and-go and dynamic. On the stop-and-go option you would select your collection interval and how you would initialize to obtain lock.

Maybe the issue for adding Stop-and-Go is in the post processing software? I am not familiar enough with RTKLib to know if it has built in functionality for reading a stop-and-go file.

So my advice is that if you need to collect lots of gcps in static mode (non-RTK) then it is probably best to hunt on ebay for an old single frequency dgps unit that has Stop-and-Go functionality. You will pay for it quickly if you do commercial work. And for doing static surveys old units that use only the US GPS satellites are fine. Glonass et al. are nice, but are not necessary and in my experience to not improve accuracy.

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My application doesn’t require UAV or GCPs, but was just wondering, does STOP-AND-GO pertain to UAV work and post processing or soemthing? What does this specifically mean even though it sounds self-explanatory?

Obviously I am stopping and going when collecting and staking points using Emlid Reach RS Rover (with a stationary or static Base also via LoRa) via RTK with no problem, so just wondering what I am missing here.

Thanks!

timd1971: The following discussion refers only to applications for post processing rover data against a base station. One would go the post processing route if the environment to be surveyed has too many obstructions for RTK to work consistently. Obstructions would be buildings, trees, gullies, etc.

The primary use of a Stop-and-Go survey (post processing) is when you have a project that requires the collection of a lot points. From my experience to collect a point, with a reach unit, that will have a fixed solution requires a 10 min static collect. Well, if you have 30 points to collect, that is 5 hours total needed for data collection, not taking into account the time moving between points. Each collected point is essentially it’s own survey project. If instead you are able to do 30 secs on each point in a Stop-and-Go survey, that is only a total of 15 mins of time. A big difference. And accuracy is essentially the same. However, Stop-and-Go surveys are more complicated to implement at the software end of things. A Stop-and-Go survey is essentially one long dynamic survey (PPK) in which time marks for the start and stop of each point are embedded in the file. The key for this type of survey is that “lock” is maintained for the entire survey. Stop-and-Go surveys will throw up a warning if lock has been lost at any point during a survey. In that case the unit would be reinitialized before continuing the survey. Loss of lock might occur, for example, if you were surveying in an open field, but then had to walk thru a forest to get to the next field. Chances are you would lose lock in the forest. In this case you would reinitialize once you were in the open again and then continue your survey. If you were using RTK you probably would not get a fixed solution because now you have a row of trees between you and your base. With Stop-and-Go you only need a good view of the sky. Stop-and-Go surveys can get frustrating if one looses lock often.

As others have pointed out you can just do a dynamic survey using the Reach units and do a poor mans Stop-and-Go survey by recording the start time of each point. The real issue with this approach is that it is a hassle to put together back in the office and more importantly you will never know if you suddenly lost lock during the survey. You will find out back in the office when you only get a float solution for some or all of you points.

Google Stop-and-go surveys and watch some youtube videos to get a better idea about these type of surveys.

The other reason to do a Stop-and-Go survey is that it does not require any radios, so two more affordable Reach M+ units could be used to conduct a very accurate survey.

I absolutely love the RTK capability for the Reach RTK units. When in environments where they work, they are awesome. But having the ability to do a PPK Stop-and-Go survey when the environment is not conducive to RTK would be really nice. Then you’d never be trapped for results.

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Thanks for the great education on that!

thanks

Really a wonderful illustration of the actual problem…Kudos to you…

Thanks

No…

The information is really awesome…

Thanks

Basically all that meant is that it takes the Reach RS receivers too long to obtain a fix. I use professional grade survey gear and you should still collect for at least 10 seconds if you want real repeatable accuracy. Base network control points are shot in for 60 seconds. The Reach results are good enough for GCP’s, but only as long as you can maintain a fix and it will take about twice as long. If your environment doesn’t allow for a constant fix then forget it, which is what I have experienced. It’s all about the ability to quickly get a fix and maintain it. L1 vs L1/L2.

…and if you have a fix 10 minutes is not needed.

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And with I assume you are only talking about RTK and not PPK?