If we consider the example at 0:42 to be North , then -4 = north / +4 would be south be east and west would produce no change so then you need more magnetized bars to to compare all the AC responses and therefore your heading.
@@georgekurian7408 Flux gate sensors are the most widely misunderstood principal I know of. Apparently even NASA doesn't get it. I have built such things and designed around them. Great magnetic trickery!
