Strange Moving Band in My Monitor

[Willie 0]

I just installed a camera at the end of my driveway. The total distance from the camera to my 20 inch LCD monitor is about 600 feet. I used an unshielded twisted pair for the 600 foot run, with NVT baluns at each end.

 

In general, I am pleased with the picture displayed on the monitor. However, there is one artifact that bothers me. About every 15 seconds, a dark horizontal band (about 2 inches wide) starts at the bottom of the screen. It then progresses from the bottom to the top of the screen in about 15-20 seconds.

 

I have two questions: What is causing this, and how can I get rid of it?

 

Thanks, Willie

[VST_Man 1]

- check to see if the cable is crossing any power lines, if yes, seperate.

- Ground Loop...........caused by difference in camera potiential (ground) and DVR/monitor potiential. To test, have someone watch the monitor and then remove the camera from the object it is mounted to, do not disconnect the video or power, just seperate the camera from the mounting platform (building, pole, ect.) Make sure that the person holding the camera is wearing rubber gym shoes and not grounded.stay out of water, off metal ladder, ect. If there is a Ground Loop problem the bar will disappear.

- do not ground the camera and if possible use a nometallic surface as the mounting. Thick rubber works if used right

- 600ft. outdoor? If yes, what type of cable? CAT5 indoor? You need direct bury on all your outdoor CAT5 runs............gel filled is the best.

 

if you had a CM-2 (camera master) test meter you could test for Ground Loop without the funky method above..but it does work. My guess is you have another wire/circuit crossing the video cable.

[brandontrjn 0]

The problem is not with the cable. If the problem was with the cable, you would most likely have constant interferrence. You will want to look at your television! I forget the technical name for it but there is a screen roll feature. Older televisions had this problem if you think back to your younger days. It used to be a knob on the television to adjust it to the signal. You will want to look into solving this problem rather than a cable problem.

 

BTW over 600 ft of un-shielded cable and you still get a decent picture...your lucky for that

[VST_Man 1]

hey, bet your pay check on it? I'm just trying to help. And if you can with 100% accuracy (from the safety of your PC) know that it is not a cable issue...........I am wrong.

 

I'm taking my ball home now..............

[Thomas 0]

The problem is with the cable and the shielding speficly. TV signals are timed at 60 hz which happens to be the same frequncy that AC power runs at. (This is where the 60 ips comes from.) That rolling bar comes from the camera and the TV being out of sync. If it was constant then you would blame the TV. But the intermittent problem shows that it's a power line being turned on and off.

[cctv_down_under 0]

Just for crap and giggles....assuming that you are running 24v power to the camera or that you have a polarity protected 12V camera...go tot he PSU for the camera and reverse the polarity if it is not a plug pack of course, you may get lucky