This is a bit different but its driving me nuts. I had my Mavic 2 pro replaced for a new unit 3 weeks ago. I have noticed this high pitched beep coming from it whenever its in flight. Its not an alarm or coming from the controller, and it only happens when the drone is in flight, even hovering low near the ground or moving through the air. If the props are spinning but the drone is not flying, its not there. Thinking it might be sonar noise, I have disabled the sensors and landing detection, turned off the bottom lights and everything else I can think of. The amplitude is uniform all around the drone. Its driving me nuts trying to figure it out. Does anyone else hear this on their M2 pros or other drones. To hear the tone, mentally filter out the regular prop noise and listen for something that resembles a truck reversing. Its ver low volume but at a pitch that I can hear from 10-20 metres away, although this recording was made from about 1 metre away, hovering about 2 metres off the ground. Its still there if the drone is 20 metres of the ground.

Other than this beeping, the drone is working fine. The motors spin smoothly, there is no catching or scratchyness when hand turning the props, the props are stock DJI and the drone has only flown a few hours with no creahes or knocks. It is housed in a hard case and well looked after.

Here is a link to a recording I made of the sound.

https://youtu.be/r7Lql4hquRg

Hello, there. We are sorry for the inconvenience. About your issue, we will confirm with our engineers first. If they reply to us, we will update here. Thank you for your understanding and support.

Thanks.
At one time, I thought it might be an esc alarm or find my drone beep, but the volume is very low and there are no vibrations etc.

I have done another recording. This time I rotated the drone in front of me from about a metre away (wearing suitable protection) and recorded the sound. The reference to recording positions is made to front right and left propellors, rear right and left propellors (front obviously being where the gimbal is). Recordings were made with the relevant propellor pointing at the microphone. I then also recorded the sound directly from each side of the drone.

The sound is at its strongest when the right hand side of the drone is facing the microphone, and at its least when the right hand side is away from the microphone. Please see drawing for more info. I have also included a new recording. It seems the noise is strongest on the right hand side, possibly mainly the rear right prop/motor.

A sketch of the recording positions on the drone.

Final piece of information. When I attach the plain pgytech prop guards to the right hand side of the drone only, the sound goes away. See attached recording. When I take the guards off, it comes back. So, no guard attached, tone is there, guard attached, tone goes away!

psteel Posted at 6-3 17:34
A sketch of the recording positions on the drone.[view_image]

Hello, there. We received the response from our engineers.
There is no apparent abnormality based on the video you uploaded.  
The motor noise mostly comes from:
(1) Electromagnetic noise: Noise produced due to motor structure vibration from the motor’s alternating magnetic field;

(2) Mechanical noise: Noise produced due to bearing operation and motor vibration when the motor is running;

(3) Aerodynamic noise: Aerodynamic noise is produced due to the impact and friction of air inside the motor when it is running.

In most cases, “abnormal noise from the motor” is a kind of perceptual noise when the sound produced by friction from bearing rotation is amplified by aircraft arms when the motor is running.
Due to a difference between motor part dimensions and their respective assemblies, each motor runs a bit differently, which means that they generate different sounds. As such, some sounds may be mistaken as “abnormal noises”.

Each aircraft has gone through strict tests before it is shipped out from the factory and meets the ex-factory standards. Please feel free to use your product worry-free.