RS+ Manual Base Setup - Assume Ellipsoid Height?

[JonathanS (Jonathan)]

Using the Reach RS+ can I assume ellipsoid height in the manual base setup and correct in post processing? Or is there a better alternative?

I would like to setup on a know monument (benchmark) and work in RTK with a fixed position but the only known information is the latitude, longitude, and orthometric height. I can calculate the ellipsoid based on geoid models but without knowing the specific geoid model used in establishing the monument I will be off by 0.04-0.21 feet. https://geodesy.noaa.gov/GEOID/models.shtml

Can I perform a work flow like this…?

1. Assumed ellipsoid height of say 500m for manual base setup.
2. Collect survey points from the rover and points from the base over the monument.
3. Export project to csv and calculate the elevation difference between the known monument elevation and the surveyed monument elevation.
4. Apply the difference to all of the surveyed points.

Thank you!!!

[wizprod (Christian Grüner)]

@JonathanS

Using the Reach RS+ can I assume ellipsoid height in the manual base setup and correct in post processing?

Yep, input is elipsoid height

@JonathanS

without knowing the specific geoid model

If you don’t know the model, you’ll get inaccurate results regardless of doing RTK style in the field, or after the fact.

[kseniia.suzdaltseva]

Hi Jonathan,

As Christian said, you need to know the geoid model to obtain absolute accuracy with these known coordinates. When official services provide benchmark coordinates, they usually comment on the coordinate system and vertical datum used. I suppose it should be possible to find this info.

Alternatively, you can find out the accurate base’s coordinates with the help of a local NTRIP service. For that, provide your Reach RS+ with corrections from a remote NTRIP base and average its position in Fix.