Can anyone provide me with the size of the 6 spacers between the VOXL flight and the green plastic board it is secured to (the deck)? I would like to order some extras, thanks!

I only see discrete options for baro, GPS, range finder, and vision as possible values for the parameter EKF2_HGT_MODE. These are defined in the PX4 docs here

My understanding is that the PX4 EKF requires the definition of a primary altitude sensor (via EKF2_HGT_MODE) and then all additional altitude data is fused to estimate altitude, but that PX4 does not support the definition of multiple primary altitude sensors.

If this is incorrect and you are aware of a parameter to enable this behavior I would be happy to try it out!

What is the expected accuracy of altitude estimation in PX4? With a good satellite connection (19-20 satellites and HDOP of 0.6-0.7) and the addition of a range finder should I expect the altitude estimates from PX4 to be accurate/steady? If yes, is there any suggestions for achieving a good altitude estimate?

With the VOXL m500, I am seeing altitude measurements that are often off by 1-2 meters, and fluctuate up to 1.5 meters in both the up and down directions. The only way I have achieved a reliable altitude estimation is the set EKF2_HGT_MODE to use a rangefinder. However flying in this way is undesirable for my work. If EKF2_HGT_MODE is set to barometer or GPS, the altitude fluctuates significantly, causing vertical deviations in position mode. This occurs with EKF2_RNG_AID enabled and disabled.

Here is a link to my .param file: https://drive.google.com/file/d/14DA0fQ8Q4PowwlFXMUfU_w1wteXpM9rk/view?usp=sharing

I am attempting to fly the VOXL m500 outdoor using GPS without VIO. Sat count usually gets up to around 16-18 with HDOP ~0.7 VDOP~1.0. I get a valid local position and can fly in position mode, however I am experiencing large amounts of position drift (~3-5 meters along all 3 axis). That is after start up, while the vehicle is sitting still, I can see the values in LOCAL_POSITION_NED changing as if the vehicle were moving. I used the parameter set recommended in the parameter helper file for outdoor GPS flight with no luck. I also have tried tuning EKF2 with no luck. I booted up the vehicle in multiple different locations to see if something about one particular area was the issue, but the drift occurred regardless of location.

Do you have any recommendations where to look next? Unless I missed a parameter somewhere I am at a dead end in getting this resolved.