PPK - Minimum time for 10km point

Hi all,

Based on your experiences, in PPK, how much minimum time would you spend measuring a point where the base is 10km away?

Base and Rover are RS2, constellations used will be GPS-GLO-GAL.

Thanks.

If you are looking for absolute global accuracy then you will need to either have a known monument or connect to an NTRIP service to collect the point and would not need to do PPK. If you want returnable relative accuracy on your subsequent surveys then it doesn’t matter. Just let the base derive a coordinate with Averaging and then use RTK. You can log at the same time and PPK that survey to verify the RTK results or fix them if something went wrong. Either way you will need to manually enter whichever coordinate you use moving forward. You can do PPK with a base and rover, but all it is going to do is guarantee good corrections and that the rover observations are accurate relative to the base.

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The survey is for GCP. The base will be logging for aboyt 5-6hs and there is a CORS at 40km distance so it will have absolute accuracy.

The rover will go to one GCP, measure it, then move to another GCP and so on. The farthest GCP will be 10km from RS2 base. It will not be possible to mantain FIX all the way moving between the GCPs.

My question was oriented to know what was the minimum recommended occupy time for each rover point for post-process, for example 5 min, 10min, 20min, etc.

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For dual frequency systems 5 min probably will give you a fixed solution in ppk.
But why don’t you use rtk? 10km is ok for baseline. If you can’t use Lora you could use the emlid caster and send the corrections to the rover via internet.

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@vgo195 there is no good internet availability in that area, that’s why PPK will be used.

Thanks, I think 10 minutes will be good then, to be on the safe side.

That’s good. Is the project that you are placing the GCP’s for actually on the CORS coordinates and orthometric heights? This is something the drone mappers really need to watch out for. You can put the GCP’s and in turn the map on true grid coordinates and, but you may not be able to directly integrate that data with the design files. This is where a process called localization comes in and is much more accurate than trying to transform data afterwards. Especially if you are doing PPK.

I agree that a 5-minute occupation with an RS2 is plenty. I typically do 2-minute observations and verify cm-level accuracy from the drone point cloud with checkpoints.

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@chascoadmin There is a local geoid model that will be used and every image of the drone survey is adjusted, as well as the GCP.

Thanks for your answer, 5 minutes will be OK then.

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Kudos for knowing that information. That is the most common snafu in Drone Mapping. Luckily for those people their maps never make it as far as a VDC workflow.

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