SparkFun RTK Express Plus Kit - Altitude variance + Built-in Radio

Kits
1

Hi guys,

Not sure if that’s a bug on the firmware, or maybe just an imprecision, and I’m not 100% if that’s a report or a post about the altitude variance I’m getting.

So, I’m using a SparkFun RTK Express Plus Kit with an average of 30-32 satellites being found, with NTRIP corrections and my precision gets to about 200mm vertically (on the display it shows about 0.09m. But when I’m collecting the data on SW Maps, my altitude changes a lot, like, standing in the same point it changes 1-2 meters.

I just got some data this morning and it was a flat area, but I got a difference of over 3m on the reads. Would it be caused by the RTK or that could be a problem on SW Maps?

I did notice some changes on the horizontal position too, but way smaller than the vertical, not a concern.

And on e-pair mode, I imagine I could sync two RTKs. What would it be the range of the built in radio? Just an estimate on open field would be enough, but if you have a number in a populated area, that would be awesome too.

Thank you.

2

Is the antenna ARP offset being accounted for? You can also try the guide here https://docs.sparkfun.com/SparkFun_RTK_ … ification/

3

Hi Russel,

I’m not sure if it’s a matter of calibration. These are two screenshots I took standing in the same spot.

https://ibb.co/MVm1RNb

https://ibb.co/Pc0v5WX

I’ve noticed it tends to behave properly about change of altitudes between points, but it does vary a bit more than the accuracy indicates. This is just an example, but the difference is almost 1 meter. I didn’t take a screenshot about the satellites and precision on the RTK, but I was getting 31 satellites and about 0.078-0.088m of precision on the display.

Would it be the case of using another RTK as a reference base? I’m not concerned if I’m standing at 10m or 100m above sea level, but the groundline profile matters to me.

Thank you.