Merging video

[sjmaye 0]

I was wondering if there was a device to merge multiple RG59 video feeds to one RG59 cable and then split it out later when connecting to the dvr.

 

I am guessing it would be like a multiplexer. It seems this would aid installations where there are multiple cameras at a remote location.

 

Is there such a device or is there too great a chance for video noise doing this?

[rory 0]

http://www.foresight-cctv.com/VDS2500.pdf

its not cheap and only recommeded as a last resort.

 

A regular mux wont do what you want ... though if you use a high end mux, 2 of them, you can join them with cat5 and then it will do sought of what you want. GE has multiplexers that do this, and you can join them up to 10K feet.

 

Also, like what Herm sais further down the page, use NVT Transceivers.

 

Basically using Multi Pair UTP cable, you can run that to a concentration of cameras, use a UTP Block, then split off to your cameras. Each camera will use a UTP TX which can be either mounted at the camera, or at the UTP Block in a rack mount, or other way. At the head end you would have the NVT Receiver.

 

Or another way would use 2 Transceivers, run a multi pair between them. This is good if moving the head end to another location, and then you just tie in your existing coax to the Transceiver. The 2nd Transceiver goes at the new head end location.

 

Rory

Edited June 19, 2005 by Guest

[bryan1656 0]

I was wondering if there was a device to merge multiple RG59 video feeds to one RG59 cable and then split it out later when connecting to the dvr.

 

I am guessing it would be like a multiplexer. It seems this would aid installations where there are multiple cameras at a remote location.

 

Is there such a device or is there too great a chance for video noise doing this?

 

I'm thinking fiber optic.

 

Something like this?

(example only, not a recommendation or endorsement on specific equipment)

10 Ch. Video Mux w/optional 2 way data, over one fiber core.

http://www.commspecial.com/specsheets/ss-3x3x.pdf

[qman 0]

Uhm, why not CAT 5, over to a RX/TX Transciever?

[vitHoward 0]

FM Systems makes a device that does what you ask. It takes two composite video and allows them both to pass over a single coax. Obviously, it takes a pair of units to make the magic work

[qman 0]

uhm.

[jsimon 0]

easy, use modulators , very good solution and low price. Because the Coax cable has a lot of Bandwith you can have a lot of channel or frequencies in, what you have to do is convert composite to RF, this what modulator does, be sure to use modulators that you can choose the channel number, and then leave 4 channel number difference between them. At the other end use a decoder. That's it.

[vitHoward 0]

JSimon's idea will work fine if you've got the correct type of coax in place. For modulated signals a good RG6 with 65% FOIL BRAID is perfect. You'll need to calculate your signal loss. RG6 typically looses 6db per 100 ft and each splitter or combiner you use will have a loss (normally marked on the device). A good video signal is just above 0db, around 3 to 7 db is ok.

 

Cameras (composite video) work best on pure copper coaxial, ie; 95% copper shield with a solid copper (not copper covering steel) of at least 20awg.

 

Hope this helps.

[rory 0]

Quality on Modulators is not good though.

[vitHoward 0]

Rory,

I've done blind tests with a modulated signal on a tv and a composite on a monitor and no one could tell the difference.

 

As with everything we do, it takes good equipment with the right cables and correct connectors installed properly to get a professional looking image.

[rory 0]

Ive used the Channel Vision Mods, and a Cable System, with amplifiers, and still not as clear as direct input into the Plasma HDTV. Ive never seen on anyone elses TVs with decent video either using other mods. Ofcourse the quality on the TVs arent close to the higher quality on the CCTV Monitor anyway so that doesnt help .. personally i still use them, but only if there is no way to get wire to each TV.

[vitHoward 0]

Rory,

Have you checked the signal level at the television? I found that a hot signal (12db or more) can cause a poor image that resembles one that is too low (less than 0db). If you don't have a meter, do the math. Use the output from the modulator, subtract 6db (at channel 4, slightly more for higher channels) for each 100ft of coax (you are using the correct type, aren't you?), and subtract the loss from each splitter, couplet, etc. If you aren't in the 3 to 7 db range, then you probably won't get a good picture.

Hope this help,

Howard

[rory 0]

Nah, I think Plasmas, and big screen Tubes, just dont like Modulated CCTV video I mean they dont even do greate with direct video input either ... 13" TVs have the best quality

 

Its Cable TV coax ... Its also amplified so thats not an issue.

Its a UHF / RF Mod, its channel 73. On the 13" Kitchen TV it is fine, except since its in 9 way view, its very very small .. the brand spanking new 50" HD Plasma, you can see whats going on, but its far from a great image. Satelite and Cable TV though are perfect, as is DVD. And its going out to several Plasmas of different brands and sizes, all the same, except the newer HD one is slightly better. When you look at the 21" CCTV Monitor though, it puts them all to shame.

[vitHoward 0]

You just unearthed another problem. Whether it's a 9" or a 60", standard composite video only has 525 scan lines. The smaller picture will normally look a lot better because the lines are smaller and closer together. On some DVD's and Satelite receivers there is circuitry that compensates for the gap between the scan lines. Your modulator won't be able to fill the voids.

 

I really hope I don't come across as a small ass. After 17 years of desiging and installing systems, I've screwed up more than most people. I can tell you a lot of things that won't work. But I've taken the time to find out why.

[rory 0]

small, or "smart"

 

no ofcourse not .. its all good ..

I agree, I realise the larger the screen the more it will pixelise .. even with CCTV Tube Monitors .. just the client wants to know why it looks so crappy on their $8,000 TV, and no explanation is good enough for someone that spends that much on a TV

 

So basically, i only use the mods if I really must, otherwise i give it the extra little bit of quality it can get, from direct input .. and/or use smaller TV

[vitHoward 0]

that was a typo, although I'm a pretty short guy.

[rory 0]