MHello,

I'd like to share my experience and experiments with the use of the sonar on my quad.

The config is the following:

-Quad 3DR base frame rev C

-880Kv motors, 11 x 4,7 props

-4S 4500 ma battery

-Sonar MB1260 XL-MaxSonar-EZL0 (bought in the 3DR kit)

Having followed all advices to habve the sonar work properly, I have shielded the cables, moved it away from propo wash, away from ESCs, i have a filtered power on it, etc.

On the bench and in certain flights the sonar seems to work fine : the sonar alt follows closely the barometer alt value.

But , erratically and without any explanation I can find, the sonar does not work in certain flights or even in certain parts of the flight as shown in the graph above. The sonar alt value (in red)  is completely erratic and not close at all to the true barometer alt (in green).

In another flight log I found this : where the sonar seems to work fine for most of the log and then breaks down for no reason:

In flight I experienced a very bad ALT HOLD with the sonar enabled : the quad did very rapid vertical movements about 1 meters amplitude (wihout any wind). Once the sonar was disabled, I had then a PERFECT ALT HOLD.

my conclusion is this sonar being used only for under 7 meters altitude, it is absolutely useless and does not bring any added value. On the contrary its usage reveals dangerous as I experienced.

I do not see what could cause such an erratic behaviour of this sonar, except a too sensitive piece of equipment not made to be used on a drone.

Funny enough, I see the 3DR store removed this model from the sensors list. Does this mean 3DR admits there is indeed an issue with this Maxbiotic 1260 model ?