help on cabling

[nbcd 0]

hy all ,

 

I am a newbie in cctv. I've just finished my first project in a factory with a Samsung SDN 550 camera , 520 , and 6 i vision dome cameras and a 3S Systems DVR. Although the client accepted the project , i'm not satisfied at all about the results. I observed that the images were not so clear as i expected and the path zones between a light object and a dark one were not clear.

 

Anyway.. i wanted to ask you if the shielding from an utp cable must be connected to a ground or something.. Somewhere in this project i had to run a 180 meter utp cable to link the DVR video out with an LCD that was placed in another building , so i used tho baluns from GE security(passive) . I observed that if the shield isn't connected to the ground there are some lines that are over the image (hum,noise) but if i connect the shield to the DVR's case those lines dissapear but the image is distorted in the upper 1-2 centimeters of the screen. (something like little waves) .

 

Please let me know from your experience what should be done with the shields of the cables,what i have done wrong? What is better to be used UTP or coaxial? and which is the maximum cable length for the coaxial RG59 ?

I will appreciate if you paste a link about ground loops , that i don't know anything about.

With respect.

 

Eugen.

[wattwire 0]

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The "u" in utp stands for unshielded. There is a casing, but it is not a conductor. So the answer is "no", connection to the baluns is all you need.

 

-dw

[survtech 0]

Anyway.. i wanted to ask you if the shielding from an utp cable must be connected to a ground or something.. Somewhere in this project i had to run a 180 meter utp cable to link the DVR video out with an LCD that was placed in another building , so i used tho baluns from GE security(passive) . I observed that if the shield isn't connected to the ground there are some lines that are over the image (hum,noise) but if i connect the shield to the DVR's case those lines dissapear but the image is distorted in the upper 1-2 centimeters of the screen. (something like little waves) .

What shielding? If you are using utp, there should be no shielding; just 4 pairs of twisted cable. Attach a balun to the same pair at each end using the same colors at the baluns' (+) and (-) connections and you should be good to go. You should not use other cable types (ie. shielded pair) or other cable sizes other than CAT-5, CAT-5e or CAT-6.

[Silverwolfe 0]

"180 meter utp cable to link the DVR"

 

I know this thread is no longer new but I had a similar experience with a distance run just recently. I solved the lines on the screen by using Active Receivers at the DVR and Passives at the Cameras.

 

Worked great.

 

-John Wolfe

[Soundy 1]

Hmmm, nobody's paying attention here... the OP wasn't talking about standard CCTV baluns.

 

...180 meter utp cable to link the DVR video out with an LCD that was placed in another building

 

Passive VGA baluns can be tricky things. Most recommend STP rather than UTP, and most support limited resolutions, especially as the runs get longer. Some have phase-adjust screw, others have a button to force an automatic re-sync once they're connected... and a tap of the LCD's own auto-adjust button may be necessary afterward to align the display. All of them should state in the documentation what resolutions and refresh rates they support over varying cable runs. I've found usually you just have to start at lowest res (800x600) and work your way up to find the best.