I bought used, an original 3DR DIY Quad with the genuine Pixhawk early version, and have rebuilt it after a crash (bad motor, bad GPS cable, bad I2C bus/board).
So I go through the entire setup, latest f/w and Mission Planner, calibrate everything, etc.
I see the internal compass has very high offsets (500+), so I turn this off and only use the GPS/compass.
I also have no voltage on Telem1, so Modem Radio is hooked to Telem2.
I'm using a cheapo 915MHz radio modem set, no camera or gimbal.
I take off in Stabilize mode and it flies great, hovers perfect, control response is great.
I land, switch to Loiter mode. As soon as I start to increase throttle the quad starts jumping around on the ground, then does a slow flip to the left. I'm on grass, so nothing broke. I try it again and same results.
I switch back to Stabilize and it flies normal, even auto lands with low battery voltage.
So, I'm guessing a bad GPS (from crash w/prior owner). Even though HDOP was 1.4 with 8 sats ????
Thanks for the support!
I finally figured out how to look at the logs:
Log File C:\LOGS\5.log
Size (kb) 2957.9755859375
No of lines 42414
Firmware Version V3.1.5
Firmware Hash ee63c88b
Free Mem 0
Skipped Lines 0
Test: Autotune = NA -
Test: Brownout = GOOD -
Test: Compass = WARN - Moderate change in mag_field (25.80%)
Max mag field length (585.72) > recommended (550.00)
Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = FAIL - Min satellites: 0, Max HDop: 99.99
Test: IMU Mismatch = GOOD - (Mismatch: 0.17, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = WARN - Motor channel averages = [1368, 1452, 1315, 1460]
Average motor output = 1399
Difference between min and max motor averages = 145
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC = GOOD -