Picture Problem

[hundleton1 0]

i own a few shops which i have installed CCTV in in the past year, i have just decided to add another 2 cameras to on of the existing systems, i am having picture problems with the latest 2 cameras, i am getting a really bad picture on them, lines moving down the screen, poor quality in general, i have checked all the connectors and the cameras are fine, i am using rg59 cable and the distance is less than 30 meters.

 

i normaly use ct100 and have not had problems with that but have ran out. in my other shop i am also getting some faint lines moving down as well on one or two of the cams.

 

any ideas would be great

[rory 0]

Whats ct100?

 

Also, what wire are you using to power them, and is it far enough away from high voltage, both video and power cable ..?

 

Have you tested one of the cameras direct into the cctv monitor?

 

Rory

[bob the b 0]

CT100 is cable, supplies have disappeared since the manufacturer "Raydex" was taken over.

 

Rory, look on it as an upmarket RG6, used mainly in the installation of sattelite tv, which is low loss and suited to external situations better than RG6.

 

hundleton1, if its any help H109 is a similar cable to CT100, although RG59u should have no issues at 30m unless you are using twist on connectors.

Rory

[rory 0]

what about RG7 .. or 11U ..?

 

man i gots my twist ons doing 800'

[hundleton1 0]

no all connectors are crimped, i think it may be ground loop problem, the shop used to be two separate houses, the new cameras are in the second part and i have connected the new psu in there rather than run a cable back,they do have separate electrical supply's.

[bob the b 0]

If they have seperate psu's check they are outputing enough power, if the psu is too small an output, this will create problems.

[Cooperman 0]

hundleton1

 

The symptoms you are describing sound like classic 'earth loop hum' (ELH), and if the building was originally two seperate properties, the chances are very likely that they were earthed at different points. If the cameras are 24v AC or AC mains powered, then that is indeed the likeliest explanation.

 

If you use a short test lead between a 'problem' camera and a locally powered monitor, the problem should disappear if it is ELH.

If you haven't got a test lead, try running a mains extension lead from the camera part of the building, and plug the monitor into that; then test with the video cable from a single problem camera.

 

If it is ELH, you could use isolation transformers on the camera cables, or alternatively, as it's a relatively short cable run, you could install a new earth lead for the cameras, taken from the 'monitoring' building.

[cctv_down_under 0]

I would also make sure that if you are using a PC based recorder and the video source is selectable that you ar using the correct one, as PAL in NTSC looks terrible and can give that result but usually with a B/W Image in the backgorud, sounds a lot like an earth loop but hard to say without seeing the video file.

[tikitornado 0]

If you think this might be a ground loop try getting an in-line product like this,

 

http://www.securityinfowatch.com/article/article.jsp?siteSection=426&id=4840

 

If problem is a ground fault it should go away once it is isolated. If camera power supply and monitor/ recording equipment are powered by separate AC power circuits there is always a potential for ground differential. Example different buildings; sometimes different floor or room in same building.

 

Also some video distribution amplifiers have built-in ground loop isolation, just look around there are many type products to solve this...

[jisaac 0]

try an ac line conditioner