Scrolling Interference On Cctv?

[ChrisPBacon]

Hi,

My CCTV system runs through my pc (GeoVision GV800 card) and I've got two very slowly scrolling bands of distortion.

Anyone know how to get rid or what might be causing it?

Many thanks.

[Johnny]

Hi,

My CCTV system runs through my pc (GeoVision GV800 card) and I've got two very slowly scrolling bands of distortion.

Anyone know how to get rid or what might be causing it?

Many thanks.

First thing I would check is the power to the cameras

[avcctv]

First thing I would check is the power to the cameras

Ditto, sounds like a duff psu.

[arfur mo]

Hi,

My CCTV system runs through my pc (GeoVision GV800 card) and I've got two very slowly scrolling bands of distortion.

Anyone know how to get rid or what might be causing it?

Many thanks.

Hi Chris,

this really indicates an earth loop problem to me, possibly where you have made through joints and the plugs outers are touching between camera's. if you cheated and used terminal block you need to keep any exposed inner conductor to as minimum as possible, always best to fit proper plugs.

disconnect all camera inputs except 1, if that picture is ok add in the others one by one to see if two are causing the problem, you might have place your coax cables to close to mains operated devices like florescent lights which have a decent degree of induction.

otherwise it's obvious to check the easy bit's next. with camera's connected and powered, if DC supply voltage is used then set your meter to a low AC Volts range, measure across the 12 volt supply for any readings, should not get more than 0.3 of a volt. id more PSU is not being smother and rectified properly

there is a filter called a humbug' which removes many forms of interference but they are not cheap.

regs

alan

[magpye]

there is a filter called a humbug' which removes many forms of interference but they are not cheap.

regs

alan

http://www.tectonrd.demon.co.uk/humbug.html

[Guest]

Hi Chris,

this really indicates an earth loop problem to me, possibly where you have made through joints and the plugs outers are touching between camera's. if you cheated and used terminal block you need to keep any exposed inner conductor to as minimum as possible, always best to fit proper plugs.

disconnect all camera inputs except 1, if that picture is ok add in the others one by one to see if two are causing the problem, you might have place your coax cables to close to mains operated devices like florescent lights which have a decent degree of induction.

otherwise it's obvious to check the easy bit's next. with camera's connected and powered, if DC supply voltage is used then set your meter to a low AC Volts range, measure across the 12 volt supply for any readings, should not get more than 0.3 of a volt. id more PSU is not being smother and rectified properly

there is a filter called a humbug' which removes many forms of interference but they are not cheap.

regs

alan

I concur this is almost definitely an Earth loop if your cameras are mains. You won't get an earth loop on low voltage cameras as there is only one path to earth ie: your PC. An Earth Loop exists where there is two paths to earth ie: your PC and your mains camera. You can prove this by disconnecting the earth wire on the camera temporarily, obviously for safety reasons you must reconnect it and then pay some cash for a earth loop filter ie: a humbug or similar.

What Arfur mentions with wiring running next to mains is Induced AC Voltage. This seldom manifests in scrolling lines, normally a bad picture. To test for this you need a multimeter on low AC and measure from DC + to electrical earth, like Arfur says you shouldn't get a high reading.

Is the system in a house or business? If it is in a business it is a possibility that you have your PC on one electrical phase and the camera connected to another (again if it is a mains camera), this problem normally manifests itself as a teared picture though.

Dave

[TSS]

Also may be caused by more than one camera on a PSU?

TSS