Still dealing with long cable run problems

[Bob La Londe 0]

Ok, I tried a Post Equalizing amplifier. I could almost straighten out the image, but it still seemd to have horizontal distortion. It is possible there may be a ground loop problem, but I don't see how to isolate it. The cameras are all in metal enclosures attached to metal buildings. I am also not convinced that is the problem. On two of the worst locations I can replace the camera with a new camera and it will work passably for a couple days to a week.

 

Pulling new cable does not seem to be an option. I had considered running cat 5 and baluns, but I would have to do it out of pocket. Since I told the customer before hand that they might have exactly these type of problems with the longer cable runs I do not feel that is approrpiate. Since a couple of the runs are over 1100 feet I would have to special order cable in order to run continuous unbroken runs.

 

I did run across an amplifier by Pro-Video that might help. I'm not sure how well it would hold up, but here it is.

 

http://www.specotech.com/cart/products/productDetails.asp?prodID=356

 

Has anybody used one of these to solve long cable run problems?

Edited June 29, 2004 by Guest

[Randy 0]

Can't be much help with your long cable runs. But had a case similar with yours mounting cameras to a metal building. Couldn't get rid of the ground loops until I "insulated" the camera mount from the metal building.

 

Randy

[Bob La Londe 0]

How did you isolate them?

[rory 0]

If you are going to run cat5, at that distance, you would need an amplified UTP tX and Reciever, as over 700 feet, passive apparently does not work well with DVRs.

 

 

From NVT tech Support:

 

"Passive to passive video transmission over UTP will have image loss similar to RG59 at same distance. This is because the signal is attenuated by the resistance of the cable. If you intend to use a DVR or DVMR at the monitoring end, you should limit passive to passive transmission distances to 750' or less. (Digital recorders will reject or muddle video signals after 6-8dB of loss)

 

From our experience, passive to passive transmission within distance spec (750' or less to most dvrs, 1000' or less to analog equipment) is quality video. However, if you were to do a side by side comparison of passive to passive video at maximum spec distance versus video from an amplified hub at the same distance, you would notice crisper video from the amplified receiver because the amplified receiver gives you the ability to boost the signal back to the same level it was at when it left the camera."

[AVCONSULTING 0]

Get your distributor to sell you this on a trial basis. If he doesn't carry Vicon you can get something similar from Pelco.

Vicon is the V235GLTA.

 

 

http://www.vicon-cctv.com/pages/prodindex-frame.html

 

Pelco is a GIT-100

[Bob La Londe 0]

Ok... I ordered a ground isolation unit. Went with the Pelco since it was the one they had on hand. Its a GIT100 not GIT-100 I'll see if that helps. I'm not very hopeful at this point. I still think I need to put an amplifier near the source on these longer runs. We shall see.

[Randy 0]

I hate to admit this but I used some pressure treated wood between the metal building and the camera mount. I tried to find some heavy thick plastic but couldn't.

[rory 0]

I cant remember if you said you did or not, but did you connect the cameras direct into a monitor or TV at the end of line, and leave it to see if the image is ok like that? I had a DVR with a bent BNC board, bad from the factory, had lines coming and going, had to just replace the DVR.

[Bob La Londe 0]

I did ry them connected directly to a monitor at the end. They were distorted still.

[mcs 0]

I had a similar problem over a few months ago at a storage shed facility-

 

seemed like an endless problem,

 

seriously other than pulling new cable - which would be the most expensive part of the excersise, then using low cost baluns- $ 10ea end or 4 way balun for 50 bucks ea end,

 

I actually insulated the cams from the metal frmaes with a large piece of teflon, similar to bread board material-

Fixed the problem, its a prb when connecting to a dvr-

 

If you have multiple cable runs or camer runs in the same line area its cheaper and more reliable to run FIBRE- multimode or single.. various transmissions on one cable with splitters etc,

 

hope you solve it-

[Bob La Londe 0]

I tried a gound loop isolator on the longest run. That seemd to fix it. Now if the custoemr will only pay to fix all the runs.

[rory 0]

I tried a gound loop isolator on the longest run. That seemd to fix it. Now if the custoemr will only pay to fix all the runs.

 

are not ground loops caused from different phased electric? If so then would it be cheaper for them to put the electric on the same type of phase?

 

Im no electrician so i may be wrong here, just thinking..

[Cooperman 0]

On long cable runs, isolation transformers are usually the cheapest way to go. Having all mains supplies on exactly the same phase on large sites, is a total pain.

If you use AC powered cameras, it's (earth loop hum) a known potential problem (different earth potentials, sets up a current flow etc. etc. etc.).

If you use 12v DC cameras, and they're mounted on an insulating material, hey presto - no hum.

If a metal weatherproof camera housing is fitted onto a metal clad building, you can induce the hum, either through the earth cable or the building itself. Insulating the bracket, and / or doing away with an earth connection would cure the problem, but in many countries it would breach the wiring regulations.

If you were using a camera cabled back to a plastic cased monitor, their wouldn't be a hum, simply because a double insulated plastic cased monitor doesn't have an earth wire.

[foresight 0]

Include the UTP (UNSHIELD TWIST WIRE CAT5) or regular solution for COAX CABLE.All of our price are most favourable. You can find the CCTV amplifier under 30.00usd and UTP Video Baluan under 15.00usd.

 

 

 

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Welcome foresight:

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