Using a GoPro for remote viewing-video inteference

[m_g 0]

Hi all,

 

I am new here, but have been lurking for a while!

As the title suggests, I am trying to setup a GoPro for remote viewing/long term power for a research project, but I am having some trouble with video interference.

 

The system:

• 
  GoPro 3+
  Live feed via USB (composite signal) using GoPro Combo cable (which is terminated with an RCA connector)
  The live feed is transmitted 50 m via coaxial cable (stranded copper, 95% braided shield), and terminates with an RCA connector to a TV.
  The camera is powered by a battery eliminator.
  The power is supplied over 20 AWG stranded copper, run within the same outer as the coaxial, but obviously is outside the coax shield and individually insulated (but not shielded).
  

 

 

The problem I'm having is that the video signal is clean and looks good when the camera is run on batteries, but as soon as the power cable is energised, I get some (fairly minor) interference on the monitor, that I would like to eliminate. The interference is there whether I power the long 50 m cable via a 12 v battery (the battery eliminator converts to 4.3 v) or off 240 v AC stepped down to 12 v DC.

 

I have tried all different combinations related to the length of the video cable, length of power cable, batteries, connectors etc. and the common problem in every scenario is that the interference is only present when the 50 m long cable is energised.

 

I thought perhaps there was some common earths between the video and the power (and there may well be), causing a ground loop, but the interference is not present when a short power cable is used-and I assumed a ground loop would be visible regardless of the length of cable (incorrect assumption perhaps??)

 

I have also tried turning off all appliances/lights/mobile phones, and run the camera cable to a 12 v battery powered monitor to remove any potential AC noise, with the same result.

 

Does anyone have a suggestion for a possible solution?

 

Many thanks,

 

mg

Edited November 2, 2014 by Guest

[Kawboy12R 0]

Hi all,

 

I am new here, but have been lurking for a while!

As the title suggests, I am trying to setup a GoPro for remote viewing/long term power for a research project, but I am having some trouble with video interference.

 

The system:

• 
  GoPro 3+
  Live feed via USB (composite signal) using GoPro Combo cable (which is terminated with an RCA connector)
  The live feed is transmitted 50 m via coaxial cable (stranded copper, 95% braided shield), and terminates with an RCA connector to a TV.
  The camera is powered by a battery eliminator.
  The power is supplied over 20 AWG stranded copper, run within the same outer as the coaxial, but obviously is outside the coax shield and individually insulated (but not shielded).
  

 

 

The problem I'm having is that the video signal is clean and looks good when the camera is run on batteries, but as soon as the power cable is energised, I get some (fairly minor) interference on the monitor, that I would like to eliminate. The interference is there whether I power the camera via a 12 v battery (the battery eliminator converts to 4.3 v) or off 240 v AC stepped down to 12 v DC.

 

I have tried all different combinations related to the length of the video cable, length of power cable, batteries, connectors etc. and the common problem in every scenario is that the interference is only present when the 50 m long cable is energised.

 

I thought perhaps there was some common earths between the video and the power (and there may well be), causing a ground loop, but the interference is not present when a short power cable is used-and I assumed a ground loop would be visible regardless of the length of cable (incorrect assumption perhaps??)

 

I have also tried turning off all appliances/lights/mobile phones, and run the camera cable to a 12 v battery powered monitor to remove any potential AC noise, with the same result.

 

Does anyone have a suggestion for a possible solution?

 

Many thanks,

 

mg

 

There's a bit of confusion here (some of your points that I bolded seem to contradict themselves), but if I'm interpreting everything right it looks like you've only experienced interference when running power over the 50m shotgun cable (power and video paired like a double-barreled shotgun), right? The lack of interference when using a short power cable and an otherwise identical setup indicates to me that you have a good chance to fix things by either changing to a better grade/brand of shotgun cable or running a separate 50m power cable using the existing coax for video. There's also no mention of what kind of paired coaxial/power cable you're using. RG59, RG6? I'm assuming 59 but you never know. RG6 isn't good for CCTV. You might try a proper power/video balun for the run as well.

[Dirk_D 0]

try a set of Baluns for the video?

 

First thing: Take a cheap power strip & cut/break the ground lug off of it, and plug that in between the outlet & the TV.

[m_g 0]

Kawboy, yes, sorry that was a bit confusing. I have revised my first post to indicate the problem occurs whether the cable is energised by 12 v gel cell battery, or 240 v AC to 12 v DC.

 

The cable is not really able to be changed, it is a custom underwater cable. Im not sure the category (rg 6 etc) but will find out.

 

I am aware of baluns for cat5 cable, but are there some for coaxial as well?

 

Regards,

Marcus

[Kawboy12R 0]

Seems to me that you've tried multiple power sources on the camera and a battery powered video monitor to eliminate everything except the underwater and apparently unreplaceable shotgun power/video cable. Baluns are for UTP (cat 5, etc) cable and are meant to replace your underwater cable. Any baluns I've used aren't waterproof, so this may not be an option even if you're able to replace the offending cable with, say, direct burial cat 5e to your camera.

 

Apart from trying another 50m cable in a similar but more easily testable location (submerged in a bathtub or pond or something) to see if it is definitely your hard/impossible to replace cable that is causing the problem, you might want to try and either put a ground loop isolator on the dry end or maybe a Hail Mary attempt by using a ferrite core on the power cable. Googling "ferrite core" and "cctv ground loop isolator" will bring up lots of options.

[Dirk_D 0]

earlier this summer we had some nasty interference on a PA system from a motorized generator at the job site. I made sure everything was OK, powered my equipment with a UPS, everything worked fine. Disconnected & waited for permanent power & it was good.

 

Ground loops can be a b*tch.

[m_g 0]

Hi all,

Thanks for your input. I have actually found the root of the problem, and it is to do with available light. For some reason, in low light conditions, the GoPro produces/is more receptive to (??) EMI, or just is unable to resolve a clear picture. They have always been grainy in low light, but this horizontal interference is new to me.

 

When I put my halogen lights on, the interference disappears. So I am pretty confident that this is more a GoPro issue, rather than a cabling/EMI issue (the cable may be playing some part, but it seems that GoPros are susceptible to grainy pictures in low light anyway-this horizontal interference may be some interplay with the cable, but I fear it will be tough to sort out!!!).

 

I will make sure we have plenty of lights and we should be fine.

 

Thanks again,

mg

[FREDIY 0]

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