Listen to this sound coming from my p4

Dramface460 · Feb 10, 2017

Never heard this before. I have been on the phone with DJI several times trying to fix this annoying sound. Anyone else have the same issue. It's only heard when the drone is facing me. It's not a beep it's more of a intermediate sound. What is it. I had some issues with the VPS but after calibrating it and deleting the DJI go 4 app and reinstalling it, the VPS seems to be okay now but the beeping sound remains...

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pomonabill220 · Feb 10, 2017

Might be nice to slowly rotate the quad while it is facing you to get an idea of how the sound changes.
My first thought is the fwd. sonar, but that is supposed to be ultra sonic and not within human hearing.
Is it the beep that is happening at about 2X per second?

Dramface460 · Feb 10, 2017

Yea it's about that rate, 2 low tone beeps a second. The sound dissipates some when I turn it around. I'll have to make another video of that.

Thinking of sending it in

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pomonabill220 · Feb 10, 2017

Does it seem like the collision avoidance is working? I do not have a P4, but can you turn off the front sonars?
Also, can you try it on a table and take the props off to be able to hear the beeping better? and possibly locate it?

wa5tef · Feb 11, 2017

I recorded a video of my crashed Phantom 4 to save it if needed and on the iPhone's sound try is a loud clicking sound. It varies in intensity the closer I got to it and move around the crash site. I note this as the drone was still powered on and ready for its next flight command. The sound was only heard on the video and not "live".
Thanks
Jim
WA5TEF

Samuraiz · Feb 11, 2017

To me, it sounds like a beat frequency. Two of the props are almost but not quite Turing at the same speed. The same sound that is heard when trying to sync propellers on a multi engine RC model Aircraft.

Mimoid · Feb 11, 2017

Exactly what Samuraiz wrote. Since the four motors are close in pitch and timbre but not quite (which would be nearly impossible) a number of new harmonics are created, which are perceived by the human ear/brain as pulsating tones with a completely different frequency. Two high pitched, but slightly detuned sine waves could for instance create a deep throbbing bass sound. Tools of the trade with multi-oscillator synthesizers... ;-)

Darren Roach · Feb 11, 2017

I have not heard that before but mine makes some funny sounds but all appears to be working just fine

pomonabill220 · Feb 11, 2017

That is why I suggested removing the props and spinning just the motors to see if the sound is still there.
The motors are driven with PWM from the ESCs, and that switching frequency is audible although rather high.. somewhere around 5-10 kHz, and if they are beating each other, you could also hear a lower frequency as well as being from the props.

Dramface460 · Feb 11, 2017

Yes the sound is still there even when you remove the propellers.

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Dramface460 · Feb 11, 2017

If it's bc of the motors and one is not turning with the same speed as the rest, then that could be a disaster waiting to happen.

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pomonabill220 · Feb 11, 2017

So we have eliminated the props creating the beat frequency then.
If, while the props are off, you give it some stick input and change the RPM of the motors, does the sound change any?

Dramface460 · Feb 11, 2017

It's a less pronounced sound with the propellers off. It sounds like it's coming from the center of the drone.

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pomonabill220 · Feb 11, 2017

hhmmmm.. since I do not have a P4, and my P3 has an led on the gimbal that flashes when FW updating and the quad beeps (not the normal startup sound that is generated by the motors and is loud), IF you look at the led, is it flashing?
Just wondering if it is indicating a problem.
You could use a short piece of plastic tubing and use it like a stethoscope and go around the quad and try and find the source.

pomonabill220 · Feb 11, 2017

Seems like it is loud enough to hear over the props...

Dramface460 · Feb 11, 2017

Good idea. However when the props are off its almost noticeable. It's very noticeable with props on and flying in air. Weird that the sound it's making is a beeping sound. I should try a different set of props

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pomonabill220 · Feb 11, 2017

You could even use your phone's mic and go around and "listen" to different places on your quad.

pomonabill220 · Feb 11, 2017

With the props on, there is more load on the motors and the ESCs driving the motors, so it might be the PWM switching frequency beating that is creating the sound.
IF you have a mic and an scope or get a scope app and look at the sound on the scope.

Dramface460 · Feb 11, 2017

Yea I'll try that too. Thing is dji has seen the video I've posted here and they want me to send it in. Sounds like it one of the engines could be out of sync or something internally with a component. Don't you think it's safe to send it in. I told them since it's a Brand new drone they either got to replace this one with a new one or repair it. I don't want a refurb one. That wouldn't be right

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