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Aug 6, 2016
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Hello everyone,

It's been a long time since I created a new thread, but I had nothing unusual worth sharing happen during my flights.. Until yesterday.

So I hadn't flown my Typhoon H in a while; 2 whole months actually, since my last flight was on january 31. Yesterday I decided to dust off the aircraft, charge the batteries and take it out for a spin.

Using my no-longer-good-to-fly battery I performed the mandatory Accelerometer calib, Compass Calib (facing north) and Gimbal calibration after such a long time of being on the ground; The whole process took exactly 5 minutes (but I most definitely forgot the alleged 12.5 min wait for GPS almanac update)

I flew 5 batteries one after another and everything was almost completely uneventful, except that during the 4th flight I got a vibration on my ground station and the displayed message "Warning: Obstacle Avoidance has failed".

I have to mention I never use the obstacle avoidance feature; in fact I must have flipped the switch around 5 or 6 times on the almost 2 years I've owned the typhoon H just to test it, so other than the rareness of the message itself it meant nothing of concern at the moment. I brought the H close, flipped the OBS Avoid switch on and off a couple of times, and it apparently worked without any issue, the message didn't show again. So I resumed flying normally until I used all the batteries and called it a day.

Upon checking the flight log data, I came across a very unusual telemetry log at the moment I got the weird "OBS Avoid. failed" message. On a single row, for a fraction of a 10th of a second the following relevant data was logged:

  • Battery voltage went from 15.2v to 5.0v
  • Current showed a value other than 0.0 (87.0)
  • air speed (tas) from 2.75 m/s (9.9 km/h) to 426.34 m/s (1534.9 km/h) (lol :D)
  • GPS sat count from 20 to 6
  • press_compass_status from 85 to 3: "Mag fail GPS fail RealSense error Sonar error"
  • Flight mode from 3 (Angle+GPS) to 5 (Angle no GPS)
  • Error flag: 8 "Complete Motor ESC Failure"
  • GPS accuracy from .4m to 8.0m
(By the way this is a non-RealSense equipped aircraft)

All these value changes might look super scary, but again it was on a single data row, for a fraction of a second. The aircraft did not twitch, it did not become unresponsive in any way and it did not fly away. It was completely unnoticeable during flight except for the triggered "Obstacle Avoidance has Failed" message.

My thoughts:
  • I doubt this will be a recurring event; I believe this was a very unusual glitch of some sort.
  • I've been monitoring my batteries closely and I seriously doubt the voltage drop was real, had it been real the aircraft would've definitely blacked out mid-air. (Also battery shows no signs of degradation on any cells, internal resistance of every cell is <=7mΩ, and no puffing)
  • I'm leaning towards the "mid-flight updated GPS almanac" hypothesis based on: the satellite count flicker, unrealistic (GPS based) groundspeed spike, GPS flight mode "super fast reset" and lastly: GPS accuracy variation.
What I do know is that I'm not concerned about this, had the log file recorded this for more than just one single row it would've definitely raised a red flag, but for the time being I will store this unusual telemetry log along with the well-known split-second Compass calibration warnings that get usually recorded.

So what do you think? Could this be related to my failure to wait for 12,5 min for GPS almanac update after 2 months powered off? I'm very interested in your opinion on this particular event.

I hope you are all doing great!


Telemetry data log screenshot:

Internal Resistance of battery being used:

Flight paths (Take off spot was on the roof of the building):
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Certainly, it is not related to GPS. It appears to be simply a communications glitch. Were it to occur again I might be a concern, but at this point I find it to be more of a nuisance anomaly.

Good to see you back on the forum Jules. :)
Certainly, it is not related to GPS. It appears to be simply a communications glitch. Were it to occur again I might be a concern, but at this point I find it to be more of a nuisance anomaly.

Good to see you back on the forum Jules. :)

If only it hadn't triggered a warning message on the st16 I would've disregarded it completely had I noticed it in the first place on the logs.

Hehe, Thanks I will try to be more active around the forum

Generally, a warning message is only generated after several consecutive lines in the telemetry. A single data point excursion is ignored. I have, however, gotten warnings for Compass, 5 rotor mode and OA with for no apparent reason. It's likely to remain a mystery.
Hello Jules
This has happened to me a few times so I tapped the screen in the message went away. I I have always enjoyed your videos and the surgery you have done on the typhoon h replacing the main circuit board. Just saying hello keep the H flying buddy.
Keith Kuhn
This "special" line in telemetry data has implasible values in nearly all columns. That saying, those values are not true and do not represent real behaviour.
Possible reasons for that:
- hot reset of the flight controller SW (watchdog or something like that)
- telemetry processing was interupted by a higher priority process
- something happened due to switchover between 5GHz WLAN connection and 2.4GHz RC connection (to be serious: I do not trust those freqently switch-overs without reason)
- RF connection issues, disturbances.

I'm quite sure that this has nothing to do with almanach download. Those dat are not needed to get GPS fix. Almanach contains only correction values and data about positions of the other sats. This will be used by GPS-chip to get GPS fix faster and improve accuracy. But if you have GPS fix, then you have it already and that's it.

The warning message may be a misinterpretation of those complete nonsens telemetry data from Typhoon H. One question comes in my mind: Are there strange values or gaps in time line between the datasets in Remote and/ remoteGPS files?

Check your telemtry in the future. If this happens again, I would not trust the mainboard (processor and its memory, more probable the memory) any more.

br HE
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I think it has a lot to do with the H saying, please give me a break, I need to rest for a few minutes before you take me flying again.:rolleyes:

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