Jumbled picture on distant camera

[dahomes555 0]

Recently took over an installation at a self storage facility. Customer had 1 camera that was about 650 feet away connected over standard siamese cable. I'm not sure how it was transmitting that far successfully without amplification or using UTP/baluns, but at some point it was.

 

I swapped out all their cameras and added a full D1 DVR. Easy peasy.

 

About 1.5 weeks later, that far camera has started blitzing out. It will show a jumbled picture. It also causes the TV monitor (connected via BNC) to go all wavy. My first thought is that it's a ground fault loop. There are 4 spots between the camera and DVR where the cable was spliced for trenching under road). I thought I isolated where the ground fault loop was occurring, but just to be safe I replaced every single BNC connector in all the junction boxes. For two days the problem seemed resolved.

 

Customer emailed me today that the problem has returned. How can I fix it? The conduit is too tight to fit another cable (or pull out the existing cable) to re-run Cat5 to use with baluns. I know there are ground fault isolators. Will that help in my case? Obviously there is still the issue that it is 650 feet away, so I don't know if maybe the issue is more an issue of amplification and there is some sort of an amplifier that I could put in-line with the camera to help.

 

I appreciate your assistance.

[Soundy 1]

Can you post some stills or video clips showing the problem?

[dahomes555 0]

[cctvmann 0]

firstly i had a similar fault at a local school to me, and found out the cable was chorting somewhere, have you tried checking with a multi meter on buzzer range that the cable is clear and there are no problems with the cable itself?

 

secondly, if the cable is ok, and the resistance isnt over high maybe through a bad joint somwhere (could you splice/solder the ends and heat shrink them together therefore getting the joint out of the equation.

 

have you put a osciloscope onto the dvr end of the coax and measured its voltage peak to peak.?

[Soundy 1]

Yeah, looks a lot like a bad connection or damaged cable to me - ground loop wouldn't generally cause complete blackout like that.

[the toss 0]

650' is getting onto the limit for RG59. If it is running on 12Vdc then you may also have voltage drop issues.I think the telling factor here is these four splices. I'm interested to hear HOW they are spliced. Even quality joints using BNC-BNC connectors are going to cause a couple of dB insertion loss per joint. Add to that the attenuation from the cable run , the voltage drop on the power & maybe new cameras that draw more current ( & therfore bigger voiltage drop) & I think you are pushing the boundaries. You could try a video amp with pre-emphasis at the camera end.

[dahomes555 0]

Thanks everyone for their feedback. I don't know that there is really an effective solution at this point besides pulling UTP.

 

The four splices are all made with just standard crimp BNC connectors with a male to male adapter in between. It was probably an easier way of pulling all that cable back when it was installed years ago, but hey, there's a reason that entire row of 4 cameras was not functioning before I arrived.

[the toss 0]

Everytime I see the word "splice" I cant help but picture two bits of coax stripped & soldered up then wrapped in electrical tape

[cctvmann 0]

Thanks everyone for their feedback. I don't know that there is really an effective solution at this point besides pulling UTP.

 

The four splices are all made with just standard crimp BNC connectors with a male to male adapter in between. It was probably an easier way of pulling all that cable back when it was installed years ago, but hey, there's a reason that entire row of 4 cameras was not functioning before I arrived.

 

i once had a cctv job on at a school which involved pulling 2 x lengths of rg59 from the controls for 2 cameras in another building, i pulled those cables in in one run and the length was approx 280metres, including a catenary and conduit system, not one joint in the cables at all. hard work though.

[Integratek 0]

It seems like the signal is too weak and receiving device cannot sync on it. Checking signal with oscilloscope vs. reference camera could give better picture.

Power loss also could be an issue.

Also, some cameras seem to have a slight bit lower output voltage, so it could drop below acceptable lever over longer distance, so a video amplifier could help.

 

I've had similar problem with an RG-59 cable which was pulled through flooded underground conduit, it's outer layer - black - kind of partially disintegrated which leaded to corrosion of it's conducting shield which caused signal drop.

 

Try to solder all connections instead of using BNC's. Each such connections is actually 4 metal-to-metal contacts which have resistance and tend to corrode and stuff.

[the toss 0]

It seems like the signal is too weak and receiving device cannot sync on it. Checking signal with oscilloscope vs. reference camera could give better picture.

Power loss also could be an issue.

Also, some cameras seem to have a slight bit lower output voltage, so it could drop below acceptable lever over longer distance, so a video amplifier could help.

 

I've had similar problem with an RG-59 cable which was pulled through flooded underground conduit, it's outer layer - black - kind of partially disintegrated which leaded to corrosion of it's conducting shield which caused signal drop.

 

Try to solder all connections instead of using BNC's. Each such connections is actually 4 metal-to-metal contacts which have resistance and tend to corrode and stuff.

 

There seems to be an echo - a sure sign of impedance mismatch