How long to let base average fix?

We use a Reach RS2 for mapping crash and crime scenes, mainly in a roadway. We do not require absolute accuracy at this time. Currently, we use the base and rover system with no corrections to the base. The Base is set to average for five minutes and then broadcasts corrections to our Rover. NTRIP is available for a fee, but too expensive for now.

Is 5 minutes acceptable or too short? We use FieldGenius software which shows our points on a satellite map and they are often several feet off from the satellite image on the screen. Would a longer fix time for the base help?

Once I arrive, I can usually set up the base and let it average for up to 30 minutes during briefing and walk-through of the scene. Would this be beneficial in any real way?

Our mapping process often takes 1 to 2 hours, so I do not know if logging and post-processing is beneficial.

I am trying to convince my Department to purchase another RS2 to mount on our station in a fixed position and then use Emlid Caster. But, we are at that point, yet.

Any advise is appreciated.

Ted

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Longer averaging beyond 5mins. won’t necessarily increase your average single position base accuracy, your still going to be going to be 2-3 meters off your absolute position. I use NTRIP VRS corrections via HxGN SmartNet service and I can sometimes still see a difference of 2-4ft between the FieldGenuis Microsoft Bing background satellite map and know landmarks. At least it is a quick check on if you have enter any typo entries placing you in the next county!

[quote=“tyoder, post:1, topic:31523”]
Our mapping process often takes 1 to 2 hours, so I do not know if logging and post-processing is beneficial.
[/quote] Depending on where you are, you could process your base using OPUS Rapid-Static (15 minutes to 2 hours in observation duration) and get a more accurate Base position and then transform your rover shots.

You might want to consider using a Emlid M2 along with a Calibrated Survey GNSS Multiband antenna such as the one offered at:

for a cheaper solution, if your work area is within a 60km radius of your station.
I have used their Calibrated Survey GNSS Tripleband + L-band antenna (IP67) with good results with my M2 as a extra onsite base.

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Hi Ted,

Welcome to our forum! You have a very interesting use case!

I agree with @mark1st.john, longer averaging in the single mode won’t increase the accuracy. So, your idea with the mount point on the station is more convenient. However, note that to work in RTK you need to be within 36 miles from the station, and in PPK - 60 miles. And, of course, the base should be provided with a clear sky view, so it’s not going to work in urban canyons.

Also, I assume you can mount your base unit on the station and survey only with a rover, but @mark1st.john’s suggestion about Reach M2 is also relevant.

Our mapping process often takes 1 to 2 hours, so I do not know if logging and post-processing is beneficial.

You can obtain an accurate position of the base station with PPP services or with CORS data in Static PPK in Emlid Studio and correct points in Stop&Go. CORS data is free, and you can download it easily here.

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Don’t rely on that to evaluate your surveys. Aerial or satellite images aren’t always georeferenced to an acceptable level.

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@anna.moloko,
I know I can set the base and rover to record raw logs. However, in most cases, I will be using FieldGenius to capture and record points using live RTK corrections from the base via LoRa.

With ReachView3 app closed, I will not be able to use Stop&Go, correct?

The best I can do is use CORS to establish a more precise base coordinate. Then I would have to adjust all my points I captured, if I chose to.

Thank you, Gabriel_C

Yeah, I had a typo, should have read 60km…

Oh, I missed that you use FieldGenius to collect points. You’re right about Stop&Go, it corrects points only from ReachView 3 CSV file.

Why do you prefer to use FieldGenius? Are there some features you lack in ReachView 3?

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Uhhhhh… errrrrrrr… : /

That should read the other way around : /

I use Reach RS2 for crash scenes and crime scene mapping.

  1. I need to capture offset measurements where I cannot get a fix. This includes building corners, areas under a building canopy, bus stop shelters, etc. FieldGenius easily allows me to capture offset points along a line or perpendicular to a line that I could not normally get.

  2. I like to use a set code list that does not require me to type each point name.

  3. FieldGenius allows me to attach photographs to control points and special points of evidence.

Ted

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Thanks!

I will pass these feature requests on to our devs. It’s helpful for us to see what you use in your usual workflow.

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