TV capture from cable input has horizontal bands of noise

[beamguy]

I have a Leadtek TV2000 XP expert video capture card, and while it performs remarkably well with very clean input signals I am having trouble with noise in the picture when viewing and capturing off the air.

The pictures below show horizontal “translucent” noise bands that flicker quickly up and down on the screen.

These bands appear to be a modulation of the intensity, and show up most with dark backgrounds. They show up most on the higher channels of my tuner, and depend on cabling of the RF signal (Comcast cable). If I run the coax through my VCR first something in the VCR input/output section greatly reduces the amount of noise. This improvement happens even when the VCR is unplugged. From this observation I conclude that this is not EMI interference coming from the computer, but instead is some sort of noise coming in on the cable.

My VCR (a cheap Philips model) is totally immune to this noise. The tuner in the capture card seems very sensitive to this noise, and would be un-watchable without the filtering provided by the VCR.

Does anyone know how I can create a better filter to clean up this noise, or should I RMA the card and pick another?

-thanks





The following two pictures have been enhanced to highlight the noise

[GreatSinatraFan]

I have the same thing in my cable set up as well...it's called "GROUND LOOP HUM" - I've done some research; it appears that when the cable guy set up the cable outlets in the house; he didn't ground it properly.

I suppose that I COULD call the cable guy back..OR get what is called a "GROUND BREAKER" - as advertised; this cheap gizmo ($8.00) is supposed to eliminate the Hum Bars that appear on the TV screen.

I've not ordered it yet..still contemplating if I should call the cable guy back..BUT you can see the advertisement here =
http://www.xantech.com/

(go to PRODUCTS, scroll down the page till you see "GROUND BREAKER".)

Some guys here at DVDRhelp.com have recommended other solutions.. but I'm not tech savvy enough to really understand what they were saying.

Do a search on "GROUND LOOP HUM"; you'll find some information.

Sorry that I couldn't help you more.

[jarvizo]

I had the same problem -but I was also getting massive audio hum as well as video noise in my captures. It all points to a Ground Loop Issue.
The most simple solution & cheapest was a homemade ground loop isolator. First get 2 high quality 300 ohm to 75 ohm (2 bucks apiece at radio shack) connect them together (best way is to solder the two 300 ohm ends together so you end up with a contraption that has the female coax's on either end. Place this anywhere along your cable line prefferably before its splits to all your inputs (ie home theater set up, capture card, additional tv's ect) So simple yet huge difference on captures. Let me know if you you want to try this & need pics or anything else.

[GreatSinatraFan]

Jarviso;

YES.. I would like some pictures of this gizmo; sounds like something that even I could make. ('cept.. I can't solder- dunno how..maybe I could bind the 300 ends together with electrical tape)

[vhelp]

Hi jarvizo,

yes, I would be interested too :P - - - (my ATI-TV Wonder card)

I've ben suffering from this noise issue for the longest of times, but I don't
think it will work in my situation, though I have similar bars as those pics
above, but not to that extent, I don't think. But, your idea was the first I've
ever seen, and even I would give it a try - I do have some electronic experience
.
.
But, I'm not capturing from cable and I don't use satellite anymores.. too
much noise (blocks and they all seem to be jimmy'ing the channels sources
nowadays)

But, if I'm capturing from s-video, I don't see how your gizmo-d'gram will
help me then ??

Thanks,
-vhelp

[johns0]

I posted the same idea about 2 fm adapters about 2 weeks ago when someone else here mentioned it,it works great and no more hum bars or audio noise,make sure you shield the connections you make also.The noise will affect s-video capture also when outputing from tape unless you unscrew the cable in but that`s a nuisance so it best to put in the filter.

[lordsmurf]

I had the same problem -but I was also getting massive audio hum as well as video noise in my captures. It all points to a Ground Loop Issue.
The most simple solution & cheapest was a homemade ground loop isolator. First get 2 high quality 300 ohm to 75 ohm (2 bucks apiece at radio shack) connect them together (best way is to solder the two 300 ohm ends together so you end up with a contraption that has the female coax's on either end. Place this anywhere along your cable line prefferably before its splits to all your inputs (ie home theater set up, capture card, additional tv's ect) So simple yet huge difference on captures. Let me know if you you want to try this & need pics or anything else.

Please post pics.

[BrainStorm69]

Go to this page and scroll a little past half way down. I believe it has a picture of what he is describing...

http://www.siber-sonic.com/broadcast/GLoopFix.html

[johns0]

Here`s something simpler.

[NightWing]

You may be able to put TWO caps in line if you cant find a completly isolated one. Notist that on a old sony transformer. One goes in each line. Not one after another.

I am guessing its about .1 or maybe .2mf ceramic disk should do. My cap meter is dead right now. So its a guess from strange marking on one.

Use to put a cap in line on both out and ground esp on polarity nutral communication gear.

PS: From sone of the links it looks like .02 or .01 mf will do.

[jarvizo]

You all beat me to the punch with all the pictures, they are exactly what I used - sort of. simple solution to the most annoying capture gremlin!!
I took some pics of mine for someone who PM'ed me for them but the ones already posted are clearer.

[smaig]

Hello:

Does anybody know where such ground breakers can be found in Europe?

Thanks.