I have lurked on the forum for a while now - a great bunch of people and knowledge on here.
I have an S800 DJI frame converted to using a Pixhawk 2.1 FC and Here GNSS mounted on a post about 15cm above the top deck - so far I have been absolutely delighted with the performance. I normally operate it with a 32bit Alexmos gimbal onboard and take oblique images for photogrammetry.
I now have a need for much better positional accuracy both relative and absolute and nadir only images. I have just added a custom nadir Sony camera mount with triggering by a Seagull Map2 from the Pixhawk and hot-shoe feedback to an onboard Emlid M+ with antenna mounted directly above the camera optical axis, minimising lever-arm displacement (although I am working on calcs from the Pixhawk IMU data to calculate these). All systems are working well on the ground (weather has been shocking lately, so not had a chance to test fly). I have for the Emlid, RTK working well from a base station feed to the copter via RTK injection through Mission Planner.
I currently have GPS blending set and is working well on the ground. My question is, if the Emlid looses RTK fix or if one antenna fails, will there be a significant jump in positioning to cause confusion of the EKF and cause maintenance of attitude or positioning issues in auto/loiter/pos. hold/RTL modes? I know recent releases have addressed the jumping issue to a degree (I’m running 3.6.7 Chibios), but I have searched the forum and can’t find a situation where someone has tested a RTK fix solution GNSS blended with a non-RTK.
BTW when developing and building the craft, I found it hard to find relevant information on motor numbering, expected / realistic PID values for the frame and other areas - so happy to share any such information with others if they need it - just PM me.