Horizontal Lines in Video

[keefe007 0]

Hello All!

 

I just setup a new Geovision system and I seem to have a weird problem with horizontal lines scrolling down the video. These aren't the normal horizontal lines that you see with motion if you have de-interlace turned off. The lines look like something you'd see from a really old CRT monitor on its last leg.

 

I thought at first it might be cause by dirty power to the camera power supply, but I have since plugged it into an APC UPS and I still see the lines.

 

Any ideas?

[G22 0]

What is the monitor refresh rate at? What type of monitor?

 

Right click on Desktop -> Properties -> Settings -> Advanced -> Monitor... try increasing the rate from the drop-down list if there are higher options than your current one.

[scottj 0]

Are you using a cheap CMOS camera?

 

scottj

[keefe007 0]

G22: The whole screen doesn't do it, just the separate video feeds. I'm using and LCD anyways.

 

scottj: I'm using 1/4" CCD dome cameras and one smaller pinhole camera.

[G22 0]

Perhaps the BNC cable itself or interference? Not sure.

[G22 0]

Or a cheap video card?

[keefe007 0]

Well i'm using RG6 Siamese cable, which has worked well for me in the past. What could be causing the interference? It pretty much does it on all of the cameras in this installation so I don't think its the cable termination. The wires aren't routed by any flouresent lights either.

[keefe007 0]

Why would the video card cause problems just for the incoming video feeds and not the rest of the screen?

 

I believe the video card in the system is a Nvida 128 MB Fx5600.

[rory 0]

Is the interference on play back also?

[keefe007 0]

You can see a sample of the lines here -> http://www.techwarelabs.com/community/viewtopic.php?p=61393#61393

 

Any ideas?

[G22 0]

[mime type video/avi was deactivated by an board admin, therefore this attachment is not displayed]

[rory 0]

No attachment, can you email me it, email is below the sig, i can post it here for others to see if you want..

 

Also, plug a camera direct into a TV and see if the lines still exist, use the TVs AV input, you will need a BNC-RCA connector.

 

If the lines still exist then its not the DVR or PC. The next thing to check is another camera. If they all have lines then its something in the room maybe, or if they are all being powered from the same multiple supply or same outlet you may want to change that and see what happens. If only some of them still have lines, they maybe too close to high voltage, lighting, etc, or the connectors are not properly grounded. So the next question,

 

If you are using BNC did you strip the wire back properly, and leave some ground (stranded part) for the BNC connector, and also make sure that the ground is not touching the center core ..

 

Rory

Edited May 22, 2005 by Guest

[cctvfan 0]

Sounds like a ground loop problem (tho not 100% sure about your case) ---- that happens when two grounded devices are connected together, and yet drawing power from separate 110VAC outlets which do not share a single grounding point.

 

The minute potential differneces (i.e. resistances) between the two devices' "ground" would cause interference which, in the case of audio hookup, manifests itself as an annoying "audio hum" (50Hz & its harmonics).

 

For video setup, the problem takes the form of "video hum", i.e. white horizontal bands that travel down the screen (slowly), then starts from top of screen again.

 

Using a video isolator transformer may solve the problem (BTW, if you use a passive balun pair & UTP, you would achieve the same effect too, as the transmission becomes "balanced" and there is no more a common ground between the video generation and receiver ends.

[rory 0]

Yep, except with a Balun you loose quality and the video gets brighter over distance and washed out .. Hes got Siamese Cable, so I think he would have RG59 and hopefully some good quality cable, which will be a better image than passive UTP. Im thinking he would be powering them all from the same location and the monitor and DVR also, but then we dont know how he has it set up .. need some more info ..

 

definately needs to check each camera individually, and on a CCTV monitor or TV .. at the camera, and at the DVR end (but not connected to the DVR)

[cctvfan 0]

That's true Rory. I hate passive baluns too, and active ones with fancy compensation are expensive. So I would try using a proper video isolation transformer to see if it helps, and forget about baluns.....

[rory 0]

yeah i wish NVT would drop the price yah know

Ive been meaning to get my hands on the OEM Active stuff (like EclipseCCTV) but just other things too spend on right now .. and then they may not be that great and another waste of money ..

[keefe007 0]

Alright, here's a link that should work -> http://www.techwarepc.com/devel/File20050521082854.Avi

 

By the way, I'm using RG6 Siamese with the 2 18 gauge power cables included.

[keefe007 0]

No attachment, can you email me it, email is below the sig, i can post it here for others to see if you want..

 

Also, plug a camera direct into a TV and see if the lines still exist, use the TVs AV input, you will need a BNC-RCA connector.

 

If the lines still exist then its not the DVR or PC. The next thing to check is another camera. If they all have lines then its something in the room maybe, or if they are all being powered from the same multiple supply or same outlet you may want to change that and see what happens. If only some of them still have lines, they maybe too close to high voltage, lighting, etc, or the connectors are not properly grounded. So the next question,

 

If you are using BNC did you strip the wire back properly, and leave some ground (stranded part) for the BNC connector, and also make sure that the ground is not touching the center core ..

 

Rory

 

I have the cables terminated with F-connectors and I am using a F -> BNC adapter to connect to the cameras.

 

All of the cameras are powered via one power distribution box, which is connected to the same outlet that is powering the PC and monitor.

 

I can mention that when I tested the system at my office with a single cam and cam power supply I did not see these lines, so I don't think its anything in the card or the system.

[rory 0]

Ok to start with you need to get rid of the Fconnectors - BNC, as you can run into issues with them, get some twist on BNC connectors and follow the instructions, or I can post a link to how to put them on.

 

Also chck the other things i said, direct into a TV or CCTV Monitor, at both ends, start with the camera end.

[keefe007 0]

Ok to start with you need to get rid of the Fconnectors - BNC, as you can run into issues with them, get some twist on BNC connectors and follow the instructions, or I can post a link to how to put them on.

 

Also chck the other things i said, direct into a TV or CCTV Monitor, at both ends, start with the camera end.

 

What kind of problems do you see with F connectors? I've always used them before without troubles.

 

For reference, post the link that shows how to install the twist on and also a good place to get them for cheap.

 

Thanks

[rory 0]

ground problems .. the correct way would just to use the BNC ...i used the fconnectors-BNC adaptors for a while in the beginning but was just too many issues of no video, grounding problems, etc.

[keefe007 0]

What can I do to fix this problem without going back and redoing all of the ends?

[rory 0]

ok forget ends for right now, are all the cameras like this?

Also, take them each off the DVR and try it into a TV/CCTV monitor..

[keefe007 0]

Yes, all of the cameras have the same scrolling lines.

[rory 0]

isolate it. Sometimes 1 bad camera can causer all to go haywire on a PC DVR especially.

 

If all cameras look fine on a TV/CCTV Monitor, then also try taking each camera off one at a time, from the DVR.