I am using a US-D1 radar Altimeter for my copter.
I’ve been using it perfectly in loiter and auto mode from ac3.6x to 4.1.x, and from 4.2.x to the latest version, I’ve never had a problem in loiter mode except in auto mode, so I didn’t care about the noise.
Thanks for the advice and I will test it out.
I found an article about what is probably the same issue. I’ll have to do a little more research.