flickering and waves in rear camera picture

[d4rkman]

Hey all,
I installed a rear view camera in my car (a simple camera that was purchased on AliExpress) and the camera seems to work, but there is one problem: the picture in the multimedia screen is a bit flickering and there are kind of waves (I attached a picture to show you how it looks like).

Anyone have an idea what could be the problem here?
Thanks!

[Mocro]

You might not have +30, my advice is connect your + at your quadlock connection on the radio.

[d4rkman]

You might not have +30, my advice is connect your + at your quadlock connection on the radio.

What do you mean by "You might not have +30"?

[CarbonChaos]

Power supply positive 12v
Or it could just be a cheap camera sending a cheap image