High Velocity Variance momentarily

Hello everyone!
I flew my quadcopter autonomously. I observed that the normalized innovation for position in very low also the compass variance is below 0.25. There is velocity variance that is arising once in a while and the overall velocity variance is higher than any other variance. The GPS HDOP is below 0.57 and number of satellites is more than 24 all the time. Vibration values are below 30 m/s/s.

My GPS board is open and FC is also open like in simple FPV drone.

Can someone please assist me in understanding the cause of high velocity variance.
Following is the log.

I did a similar flight in the evening, earlier was in afternoon. In the evening flight I did not observe velocity variances.

The main difference I observed was GPA.SAcc, GPA.HAcc and GPA.VAcc was higher in the first log than the second one, GPA.SAcc significantly higher than other parameters.

I would like to know is this the main reason and why this occurs?

Thank you!

Hello Brian,

It seems that in Log1 the overall GNSS signal quality was worse than Log2.
Now that can be attributed to multiple causes. It could be any of different onboard components and electronics, causing difference electromagnetic noise, it could be different ambient electromagnetic noise, it could be different operational locations occluding your GNSS receiver or even a higher KP Index resulting in worse signal.

In any case, I think that in both cases the performance you got is acceptable for general operations (perhaps not for special operations requiring high position accuracy).

Thank you George for your comments.

My li-ion battery is placed around 4cm behind the gps board. My compass and gps are on the same board. As you can see the compass is working fine. If this is electronic interference it should affect compass too right?
How do I check if my GPS is undergoing interference issues, is there anything in mission planner or logs that i can see?
I want to have atleast 10-15 cm accuracy, will use of RTK suffice?

No, not necessarily.

Well… these metrics are the symptom of interference. It’s hard to get more insightful information.
Your best bet is trial and error.

That depends on your receiver. Which one are you using?
Cheap receivers can’t achieve this kind of accuracy on a good day. An expensive one like the F9P can do that on a good day. An RTK system is much more expensive but will offer you 1-2cm of accuracy.

Can you suggest some experiments that need to be done. I can perform those flights and log them.
I am using F9P gps and that is RTK enabled. I can arrange a RTK system.

Basically what I said above in post #2. Move electronics and cables around, video transmitters, that kind of stuff, and see if it helps.