Ultrasonic sensor issues

Hi all, I've installed my ultrasonic sensor today, the recommended MB1240. I've mounted it on the little protruding tab on the 3dr quad kit, which seems like it's designed for the sensor (square cutout for the inductor n all)


Tried it out and the sensor does seem to be functioning, the copter rockets up when I move my hand under it, however it also seems to occasionally just almost shut the motors off entirely for a split second.


Looking back at my logs, it seems like interference to me:



The issue is the sonar sensor mount is really close to the ESC, so the signal cable (which is shielded too) is running right next to the motor wires etc.

So I feel my only option is going to be to somehow put the sonar sensor somewhere else, but thought I'd check I wasn't overlooking something first. 

A pic of the sonar mounting: https://dl.dropboxusercontent.com/u/203420/Quadcopter/DSCF2430.jpg

The lowpass filter is also installed.




You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • Personally i think the sonar just doesnt work. i tried all sorts of options and my sonar was mounted reasonably far away from any electronics think the center space between two hex arms. The cabling was not shielded but the problem was it periodically got large noise spikes. When the Apm used these to compute its apparent height this resulted in a large bounce sometimes 2-3 meters. A few times i had an almost fly away because of said spikes, but i quickly jumped into control so nothing really bad happened.

    Disabling the sonar resulted in a much nicer experience so any comments about vibrations dont really account for the bounces from the spikes. The main factor in the bounces was obviously the sonar. They just are not worth the trouble, the barometer works well enough and given the sonar is only really used when your less than 10 or so meters this limits their utility and value.

    I can see from your graph pic, you too are getting periodic exaggerated sonar heights which my guess result in a jumpy experience.

  • In my experience with the MB1240, you are too close to the ESC, and too close to frame / batteries.

    I find they are very sensitive to secondary reflections that are close to the sensor..... AKA bounce off batteries.

    If you make a little mount, using stand offs, you will be much better off.


    Find my other posts for a pic of more advance set up (you don't need to go that crazy)



  • Admin


    Did you install the recommended power conditioning on the sonar and use a shielded cable to run the signal from the sonar to the APM?


    TCIII ArduRover2 Developer

This reply was deleted.