GPShold and GPSHome functions need an accurate magnetometer (compass)

I've been flying one of the latest quads I've built and had a problem that another subscriber asked about - how to get the GPS hold function better.
I found that this model would circle wildly and not come back home when I activated the function. The only way that GPSHold stood a chance was to have the model level and very still before flicking the switch!
The magnetometer (compass) is used, even if it's not selected in the mode, to determine the direction the model needs to take to move back to the home position. If the magnetometer has ANY interference from the power lines in the model you will see this circling effect when you select GPSHold and the GPSHome won't work either.
This video explains why a compass that is a little off will create this circling effect (also called toilet bowling!) and a few common ways to try and remove any electromagnetic interference from the board.
I hope it helps those of you who are having this same issue. Thanks for watching, please comment and subscribe.
Happy flying.