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Old 03-30-2015, 08:17 AM
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Reducing crosstalk on camera signals?

Maybe the infinite minds around here have an idea for this scenario-

Ever see those CCTV cables that have Audio/Video/Power all in one jacket? Well, I had this cheapskate idea to use a y-adapter on the power connector and try to run two cameras on from it. One using the "video" cable for video, and the other using the "Audio" cable for video. Well, it almost worked, but the signals cross-talk too bad (you can see rainbow images of the other camera scrolling across the opposite cameras monitor). This cable shares a ground, and it's very thin and poorly shielded. It runs a single camera great, but is there any way I can make this work for 2?

This is a 100ft cable.

I don't know if it's a doomed idea because of the shared ground, or if there's any kind of isolation transformer tricks I can use, etc. I just wanted to throw this out here and see if any of you VK geniuses have any ideas.
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Old 03-30-2015, 11:23 AM
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I wouldn't think the shared ground is the problem, but the poor shielding probably is (?)
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Old 03-30-2015, 12:26 PM
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If all three wires are wrapped in the same cylindrical ground shield rather than each wire in it's own ground cylinder, then essentially you have the center of each signal cable bridged to the other through a decent sized capacitor.....

If they are in their own shields, then grounding the shields together should not be a problem (and is common practice).
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Old 03-30-2015, 01:07 PM
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I think it is one common shield.

I don't have the cable in front of me at the moment. I am just brainstorming about a pair of cameras I mounted a while back. I did run a second cable up there just to fix the issue. But there still is that unused "audio" cable up there, and it'd be nice to run another camera through it someday, if I could figure out a cost-effective way to do it.

If I had it to do over again, I suppose I should have just run Cat5 and used baluns.
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Old 03-30-2015, 02:01 PM
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You can run composite video over Cat5 net cable?

One possible solution, if you feel like a design project, would be to get some video OP amps, and subtract one channel from the other to clean the one being subtracted from....
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Old 03-30-2015, 03:21 PM
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Yeah, I have a 4-channel cat 5 balun that I plan on implementing once I get a trench dug to my garage. It uses one pair per camera. So a single cat-5 run can have 4 cameras on it (with the power run separately).

They make other baluns that use one pair for video and a pair or two for power, but those look kinda clunky. I like my installs to be stealthy. I'm so anal about it, I've been known to chop off the plugs and solder/heat-shrink the connection so it's smooth, lol. Yeah, you can't replace the camera very easily anymore, but it sure looks nice! I just hate a big wad of red/yellow/white plugs and chrome BNC connectors dangling behind a camera. Sometimes I'll take a single-gang outlet box and stuff all that mess in there with a plate over it.
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Old 03-30-2015, 11:19 PM
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Good stuff that cat5... Rewired my homes phone system with it when we had the walls open for insulation...

Speaking of cameras, you have any manuals regarding a PELCO CC3751H-2 ? Found one at the auction and need info on...

SR
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Old 03-31-2015, 08:09 AM
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I googled that pelco to see what it was, and a manual was one of the first things to pop up:

http://www.selectsecurity.net/admin/...3751H-inst.pdf
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Old 03-31-2015, 04:35 PM
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WOW!!! thats further than i got looking for info, i ended up on their website and couldnt get in without login in as a company... Thanks CoogarXR YOU ROCK!!

SR
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Old 04-01-2015, 08:02 AM
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No problem, glad I could finally help somebody around here
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