How get accelerometers log

[gaucho]

Out of curiosity, what kind of antenna caused this and why flying close to it?

I was curious.
I don't know type of antenna. It seems dipoles array antenna. Around 6 meters square size

 

[Brother Dave]

Out of curiosity, what kind of antenna caused this and why flying close to it?

God question!

 

[Brother Dave]

I meant to say, “Good question”, but maybe we’ll never know for sure. That would make it a God question. I’ll ask Him when I get there. [emoji56]

 

[Brother Dave]

Or not

 

[sar104]

The moment when the copter entered inside the rf beam was not logged by the controller, this is the reason why you don't see abnormal data on the log. As you can see the copter reaches around 10 meters, then nothing else was logged.

Are you saying that you believe that the flight continued (not including the uncontrolled descent) beyond the end of the log and, if so, how do you know that? At the end of the log the aircraft was climbing vertically through 10 m at 0.33 m/s.

I don't know, at 40meters distance from that antenna, the influence of magnetic field is strong. We can assume the radiation level was around 70dBm per square meter, may be less. I don't know

Another important detail we're not taking in to account is the fact that the transmission is pulsed and the 70dBm (?) per square meter was present for (only) around 60milliseconds (then the antenna interference pointed another direction). So this short period of interference generated the problem....

I was curious.
I don't know type of antenna. It seems dipoles array antenna. Around 6 meters square size

How do you know all these specific details about the emissions characteristics but yet you don't know what kind of antenna it is? Are these statements based on measurements or just assumptions?

 

[gaucho]

Are you saying that you believe that the flight continued (not including the uncontrolled descent) beyond the end of the log and, if so, how do you know that?

No. I mean that, if it was not a problem of the processor chip, during the uncontrolled descending phase we should see sensors data logged. The fact that the descending phase was not logged, could be related to a failed write to flash memory. Do you think it's easier to jam a processor or a lvds serial line?

Are these statements based on measurements or just assumptions?

Assumptions based on my experience and internet readings

 

[sar104]

No. I mean that, if it was not a problem of the processor chip, during the uncontrolled descending phase we should see sensors data logged. The fact that the descending phase was not logged, could be related to a failed write to flash memory. Do you think it's easier to jam a processor or a lvds serial line?

I've never seen a case of controlled flight where the FC was running but the data were not logged, so my guess would certainly be that the FC shut down and the aircraft went into uncontrolled descent at the point when the log ended. If you flew into a strong enough EM field I'm sure it could have that effect. If the problem had been disruption of sensor data then logging should have continued. Your hypothesis, if I understand it correctly, is sudden disruption of sensor data and a sudden end to logging, but with the FC still functioning, which seems improbable since it invokes at least two independent failures. FC shutdown only requires one failure.

I also don't even understand what evidence that makes you think that the flight continued after the log ended. If the FC shut down and the descent was uncontrolled then there would be no record of it. If the FC had not shut down then it likely would not have crashed. The most common shut down cause is power failure, but that leads to a tell-tale signature at the end of the fast motor voltage data showing the resulting voltage sag. This log does not show that, indicating abrupt FC failure instead. Flying into a high-power directional beam from a transmission site seems like the obvious candidate for that event.

I still don't understand your assumptions about the RF transmission characteristics but that's not really important.

 

[gaucho]

Your hypothesis, if I understand it correctly, is sudden disruption of sensor data and a sudden end to logging, but with the FC still functioning, which seems improbable since it invokes at least two independent failures. FC shutdown only requires one failure.

May be you're right.

I also don't even understand what evidence that makes you think that the flight continued after the log ended. If the FC shut down and the descent was uncontrolled then there would be no record of it.

the copter didn't powered off motors when the FC was jammed. Infact the copter started flipping like if the 2 rear motors were stopped and the 2 front motors were pushed at maximum speed.
May be that after one second the copter's motors were powered off but the fast flipping didn't stopped until the copter touched the ground.
Watching the tablet display i could see the grass on the ground (I don't remember if the image was freezed) meaning that images were sent to the tablet when the copter hit the ground.

Again all these reasoning doesn't demonstrate that things are like I (or you) supposed.

It is even possible that your theory is correct.