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CCTV interference


(Richard) #1

I just got around to processing the cctv video showing the electrical interference I am experiencing. The cctv power supply and the Arduino processor share the same 12v source from topside through the tether. The ESC’s/T100’s get power from 3S batteries in the WTE. The one thing in common with all is ground. Not sure where to start with getting rid of this problem. Jacob suggested an LC circuit but since the power supplies are independent I’m not sure how that would be wired up. Any help/suggestions would be appreciated.

Here is the cctv video: https://www.youtube.com/watch?v=OWy_j5yuU74&feature=youtu.be

Thanks,

Richard


(John) #2

Are you using baluns for the cctv ?

 


(Richard) #3

No. I originally had them wired in before I was using thrusters (just dropping the camera down on a tether), but removed them when I found no difference in signal quality. Reinstalling them may be the answer to the T100 interference, so I will give that a try. I am puzzled that with all of the ROV builders on this forum, no one has experienced this problem and come up with a definite solution. Maybe no one else uses a cctv system.


(John) #4

Use two dedicated wires for the balun link… a balanced line pair should cancel any noise coupling…

If that doesnt solve the interference, try adding a 10 mh choke inseries with the 12 v feed to the cctv and a 100 ufd 25 vdc capacitor, creating an LC filter as Jacob suggesred.

Many are using streaming video via the raspberry pi module… but a dedicated pair of wires with baluns should work just fine for up to a 1000 feet.

John


(Richard) #5

John,

Can the ground wire in the twisted pair also be used for the ground for the 5 volt joystick and hold switches, or must it be dedicated to just the CCTV? I am currently using all 8 wires for ground, 12V power to camera and Arduino, TV signal, x-pot, y-pot, z-pot. heading hold, and depth hold.

Richard


(John) #6

Baluns really need a dedicted twisted pair of wires…

To test if the baluns solve the interference, you might temporarily combine depth and heading hold functions… or sacrfice one during the balun test.

If baluns do the job, we MAY be able to devise a way to command depth and heading hold over a single wire


(John) #7

If you feed your x,y,& Z pots & toggle switches to an arduino RC ppm encoder at your surface control box, you can send 8 channels of RC style commands over a single twisted pair… you would need an arduino ppm decoder down below to decode the ppm back to pwm … there are several arduino scripts to handle such tasks…

John


(Richard) #8

Well, in fact I don’t currently use depth hold (only using x,y thrusters), so I can certainly dedicate a twisted pair to the TV signal and dedicated ground. I have the baluns, so I will give this a try in the next few days.

Thanks,

Richard