I think I found the problem...
With just the WKM on quad sitting in the same spot as MK was, powered by an RX battery and nothing else connected, RX and ESC leads completely disconnected, it took slightly over 9 minutes to no flashes so it didn't appear that peripheral RFI was causing the problem either. Being the type that likes to get to the root of the problem I kept trying...
It appears the source of the RFI is the IMU itself. Even though the GPS had 7 to 8 cm of distance to the IMU it was sitting directly overhead. I bolted the pedestal to the back of the centerplate using the longest shaft and put the GPS on top giving it 5cm of separation horizontally and an additional 4 to 5 cm vertically. Again powering the WKM with just an RX battery it went full lock in under a minute, so unless it caches the satellites it finds ala MK, it did indeed go cold start to lock in an acceptable amount of time and it appears the GPS needs to be as far away from the IMU as you can reasonably get it. That also explains why folks that used a large copper sheet under the GPS had success, it wasn't so much acting as an antenna as it was shielding the GPS from the RFI given off by the too close IMU.
Now to put all the connections back and see if it can repeat that performance with everything powered up...
Ken
With just the WKM on quad sitting in the same spot as MK was, powered by an RX battery and nothing else connected, RX and ESC leads completely disconnected, it took slightly over 9 minutes to no flashes so it didn't appear that peripheral RFI was causing the problem either. Being the type that likes to get to the root of the problem I kept trying...
It appears the source of the RFI is the IMU itself. Even though the GPS had 7 to 8 cm of distance to the IMU it was sitting directly overhead. I bolted the pedestal to the back of the centerplate using the longest shaft and put the GPS on top giving it 5cm of separation horizontally and an additional 4 to 5 cm vertically. Again powering the WKM with just an RX battery it went full lock in under a minute, so unless it caches the satellites it finds ala MK, it did indeed go cold start to lock in an acceptable amount of time and it appears the GPS needs to be as far away from the IMU as you can reasonably get it. That also explains why folks that used a large copper sheet under the GPS had success, it wasn't so much acting as an antenna as it was shielding the GPS from the RFI given off by the too close IMU.
Now to put all the connections back and see if it can repeat that performance with everything powered up...
Ken
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