Base receiver not level

Is it ok if my base receiver not properly leveled.
Is there an effect in my rovers coordinates.
So what is the maximum tilt angle???

If the base is not level, then it is not directly over the point measured. Thus, your rovers accuracies will reflect this discrepancy

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How about Rover to Rover.

There wouldn’t be a rover to rover scenario but no matter what, you always want the unit that is collecting to be level. Imagine this. What may be one cm off center at the end of a 2.13m length could end up being many many cm off center once you factor in the length of the pole away from the point of the pole that is contacting the ground.

Not being level will absolutely affect GNSS receivers in multiple ways:

  1. if on a pole, being 20 arc minutes off (which is usually 1 mm off the center of the bubble, on usual 40-minute vial) (20 arcmin = 0.33 degrees), will, on 2 meter pole, equate to 1.16 cm error.
  2. not being level also means that your antenna see more of the ground, which can lead to more multi-path errors. At the same time, on the opposite side of antenna, you will be blocking potentially useful signals.

So, on all in all, not paying really close attention to your leveling might introduce errors bigger than those of the GNSS system itself!


If I have an extra unit during a GPS survey, I just leave the unit on the ground or on the roof without a tribrach or tripod. I leave it anywhere as long as you do not move it during the whole observation time. I use the rinex file from this extra unit as a backup base of sorts. I just use 0 for HI during processing.

What I mean is my base receiver (not level) but I always level my rovers pole.

Leaving it close to a surface like that will introduce multipathing, and thus you will have a lower SNR. Wouldn’t use that as a base. Get it up in 2 meters height or so.

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So you are on an unknown point, correct ?

Yes. If I need to come back next day I just do a resection and input my base coordinates manually.

With a total station?

Nope. Just the Rover.

Like Base Shift. But in reverse. You have a known rovers point. And I compute my unknown base position and input it manually.

So there no need for me to level my base receiver. I’ll setup my base everywhere I want.

Hmm… that will of course wok, but it like taking a copy of a copy. You will basically double the error of the system+baseline with this approach. Add that to the insecure levelling of the base, and you might look into 3-4 cm of errors quickly.


Hi guys,

In this case, you won’t have consistency between your measurements from different days. I don’t know your projects’ requirements, but one day this may cause unexpected difficulties.

So, I’d suggest leveling both your instruments even if you set up a base over an unknown point.

As Christian said, it might degrade your data and prevent getting a fixed solution. It’s always better to raise the base up as high as possible.


I just don’t see any reason to forego a properly setup base station. It’s not like it requires a monumental effort. Drive a nail in on the first day and then it’s a 3 minutes job to setup on subsequent days.


Completely agree !

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When sites are in difficult terrain, you want to carry a minimum amount of equipment as possible and allot as much water and food as possible. So if you can do away with 1 tripod then your team can carry a bit more water/food. I wish we had a helicopter to transport the survey team in/out of difficult terrain.

Oh, I understand completely. That’s why I designed my compact pole/tripod that I showed in another thread.

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