12D Field - Strange Heights


I am using the Emlid Reach RS2 with 12D Field.

I am based in Australia so I am using MGA94 Zone 55 as projection.

I am receiving the correct position. But the heights seem to be around 0.2m incorrect.
I have compared the Reach RS2 using the Emlid IOS App and the heights are approx 0.05m different to a known point. Acceptable for this job.

But when I connect to 12D the height then goes around 0.2m different. I assume that when connected to a 3rd party controller I still need to input Pole Height + 0.134m?

Has anyone else had an issue like this or have any thought on how else to trouble shoot?


Hi Jordan,

When the RS2 outputs its position to 3rd party software, it will output the position from the antenna phase center (APC). So you will need to configure 12D for the pole height and RS2 antenna. I’m not familiar with 12D and you will need to determine if it has ‘built in’ information about the RS2 antenna. If you are able to select the RS2 as an antenna, 12D will likely already have the L1 phase offset from APC to ARP (antenna reference point) built in (0.134m) and you will only need to add the pole height). If 12D handles the RS2 antenna generically, then you will need to add the pole height + L1 phase offset. My guess is that based on the amount you are off by in 12D, it seems to be do to this offset either being double counted or not counted when it needs to be.

The other possibility is height datum mismatch and I’ll need more information to help with that. MGA94 is only a 2D projection. You could do a quick check to make sure that both emlid and 12D are using the same height datum (ellipsoid or a specific geoid). One may be automatically applying a geoid offset based on your projection selection. If your known point has a published data sheet you could attach it here and it would help troubleshoot datum mismatches.


Hi Jordan which version of 12d field are you running?

I am using version 15.

I spoke to 12d and got it sorted. Their map projections don’t automatically use ausgeoid and just read ellipsoid height.

Rather strange I believe as every surveyor I know wants ausgeoid readings not ellipsoid heights.