Emlid

Antenna specification


(Luis Galina) #1

which are the phase center parameters of L1 to use in the antenna configuration in RTKpost


(Timmyd) #2

This may help


#3

I actually had it wrong. Its Antenna refrence point (ARP) and not Antenna phase center (APC).
Antenna phase center is unknown for each antenna and needs to be calibrated to get the exact value. The build in antenna is an OEM model from Tallysman and phase offset could be uniq for each model, antenna phase offset highly depends on it surroundings. But its to be assumed phase center is close to ARP. A test could reveal that.
On my unites it varies between few mm to almost 4cm (reach with tin foil) and varies over time. Phase offset also changes over time.
image

Edit: Now that i look at the bottom text of Reach it states phase center. So i am not sure any more. Emlid might elaborate?
Edit: or its just a really good and stable antenna and phase is close to center…


A collection of sources of z-errors when working with low cost rtk receivers
#4

Thanks for the information, what would this test look like? Put the antenna to a known position with a base station nearby and look at the difference between the known and the measured position (might be ok for a few cm, but a few mm)?


#5

Well, less then a cm. Based on values described under the RS. But not all units produce the exact same numbers and this is not done the scientific way. I would love to see a test done in a more scientific way and not just compared to other pre surveyed points.


(Luis Galina) #6


#7

The more one knows about a subject the more one realizes that one knows nothing.

When I read all these things I get the impression that the claim that you can reach a accuracy below 5 cm with these receivers is simple wrong. Their might be some where that is possible at some days but you never know.

Would be great if someone could write down a short guide to sources of error when using these receivers.
I created a topic for that purpose: link


#8

I think 5cm Z accuracy is within the spec. If you use the stated 1cm Z error and add the 2x times horizontal because of the satellite geometry.
The problem with Z controll is that you can not turn your antenna up side down and do a camparison. Like with X and Y, were you can rotate it 90/180 degrees and see if XY diviates.