Hi, after many and many tests, I finally found the jstest binary (onto rasbpian) and saw the parasites: random commands.
It was probably the USB converter (Dragonfire) that is faulty. I will receive and test a new one as soon as possible and will tell you if the parasites would disapear.
For the moment, I used an USB converter found in a little joypad (Gamepad USB) and all is works fine.
See you.