T-Adapter

[Angus 0]

Hello, i am looking at a dvr which has no loop out connections, can i use t-connectors to create a loop or will this result in a loss of quality?

 

 

Thanks!

[Soundy 1]

You can, and it will.... how bad will depend on a number of factors. Right off, you're cutting the signal level in half, so the picture will get a little darker. If whatever you're connecting to the other side of the Tee doesn't put a proper load on the line, it could get VERY dark and lose a lot of contrast.

 

Best way to do it is with active line splitters, but it won't hurt to simply test it first with some Tees.

[rory 0]

I normally dont, but i just split a cable with a T-connector right at the input to the DVR channel on a Geovision PC DVR, and no noticeable issues. Spot monitor was only approx 50' away though.

[tweak'e 0]

what i found the hard way was that if theres a fault on either leg of the T it will knock out both. in my case a problem with the screen knocked out the camera so i had no recording of that channel. using an active splitter fixes that problem.

[bpzle 0]

I know it's a no-no... but it's just too cheap to resist. To do it properly you should have a distributor amp. They aren't that expensive...

[Angus 0]

Thanks for all the replies,

 

 

I guess that brings me to anonther question, where can i get an amp for cctv then? I would need at least well i guess 2 outputs or 7db amp, ideally 12 or so? Can the inputs be overdriven?

 

What frequency does it run on? Is it under 54 mhz? If not i have lots of catv amps that should work for that purpose.

 

Thanks!

[rory 0]

Sounds like your best bet might be a 16 channel multiplexer.

or you could look for a distribution amplifier.

[ak357 0]

Thanks for all the replies,

 

 

I guess that brings me to anonther question, where can i get an amp for cctv then? I would need at least well i guess 2 outputs or 7db amp, ideally 12 or so? Can the inputs be overdriven?

 

What frequency does it run on? Is it under 54 mhz? If not i have lots of catv amps that should work for that purpose.

 

Thanks!

 

Where did you get idea about "7db" or 54 mhz ?

All you need 1 IN 2 OUT Video Distributor or any other combination

http://lmgtfy.com/?q=1+IN+2+OUT+Video+Distributor

http://lmgtfy.com/?q=Video+Distributor

Edited July 11, 2010 by Guest

[rory 0]

Where did you get idea about "7db" or 54 mhz ?

All you need 1 IN 2 OUT Video Distributor or any other combination

http://lmgtfy.com/?q=1+IN+2+OUT+Video+Distributor

 

i think he wants 12 channels looped out though.

[ak357 0]

 

i think he wants 12 channels looped out though.

 

I am trying to help him to understand basic

[rory 0]

I am trying to help him to understand basic

OK

[Angus 0]

Well 1/2 signal is ~ 3 db, hence i would need a minimum 6 db amp to keep signal same as before i split it right? So if i want to split it 3 times, i would need a 10 db amp or so? Or am i missing something thats what i'm not quite understanding here. I have a multiplexor but its only 1 in/out so it doesn't really help much in my equation, as i would need at minumum 1 in and 2 outs.

 

The reason i was asking what frequency the camera output is on, is that normal catv amps in the 7/14/whatever db variety will typically amp 55-1000 mhz forward, and then the reverse ie back to the plant is the 5-54 mhz, if it falls within that frequency, then one of those amps should work to boos the signal.

 

Thanks!

 

 

Thanks for all the replies,

 

 

I guess that brings me to anonther question, where can i get an amp for cctv then? I would need at least well i guess 2 outputs or 7db amp, ideally 12 or so? Can the inputs be overdriven?

 

What frequency does it run on? Is it under 54 mhz? If not i have lots of catv amps that should work for that purpose.

 

Thanks!

 

Where did you get idea about "7db" or 54 mhz ?

All you need 1 IN 2 OUT Video Distributor or any other combination

http://lmgtfy.com/?q=1+IN+2+OUT+Video+Distributor

http://lmgtfy.com/?q=Video+Distributor

[survtech 0]

Well 1/2 signal is ~ 3 db, hence i would need a minimum 6 db amp to keep signal same as before i split it right? So if i want to split it 3 times, i would need a 10 db amp or so? Or am i missing something thats what i'm not quite understanding here. I have a multiplexor but its only 1 in/out so it doesn't really help much in my equation, as i would need at minumum 1 in and 2 outs.

 

The reason i was asking what frequency the camera output is on, is that normal catv amps in the 7/14/whatever db variety will typically amp 55-1000 mhz forward, and then the reverse ie back to the plant is the 5-54 mhz, if it falls within that frequency, then one of those amps should work to boos the signal.

 

Thanks!

 

 

It doesn't work that way with video. You can't just boost the signal, then split it passively like you can with RF. With video, you have to actively split the signal to two or more outputs; each having the same 1 volt p-p signal and with a 75 ohm load impedance. That's where a distribution amplifier comes into play.

 

Unfortunately, it's going to cost you. An example device would be a Pelco CM9760-MDA. They have 16 inputs; each feeding 4 outputs. But they sell for well over $1000 and have other functions you might not need; like time/date/title insertion and cable length compensation. There are a few similar units on the market; I think GE Security used to make one. Or you could use 12 individual 1x2 DAs.

[ak357 0]

Well 1/2 signal is ~ 3 db, hence i would need a minimum 6 db amp to keep signal same as before i split it right? So if i want to split it 3 times, i would need a 10 db amp or so? Or am i missing something thats what i'm not quite understanding here. I have a multiplexor but its only 1 in/out so it doesn't really help much in my equation, as i would need at minumum 1 in and 2 outs.

 

The reason i was asking what frequency the camera output is on, is that normal catv amps in the 7/14/whatever db variety will typically amp 55-1000 mhz forward, and then the reverse ie back to the plant is the 5-54 mhz, if it falls within that frequency, then one of those amps should work to boos the signal.

Thanks!

 

Angus I have felling we are talking about 2 different issues

Any signal from any analog camera is baseband video (composite video)

means ~0-5 MHz

You are referring I think about RF CATV Amp 54 MHz and up

so the ? is what do u want to do ?

By the way multiplexer give composite out video

[Angus 0]

OK,

 

Thanks for all the info, i guess i will have to do some more reading and see exactly what i will need to get, to bad all companies don't put loop outputs on equipment, would make it alot easier.

[Soundy 1]

It might be more useful if we knew exactly what you're trying to do with the signal. Are you simply feeding each camera to two inputs, the DVR and something else? Or does each camera need to go to multiple destinations? Do you need to do this with ALL the cameras, just one, or just a few?

[Angus 0]

What i'm trying to get done, is to have the camera feed into a dvr, and then into a axis 241q ip encoder, they will be probably 2 feet apart, so its not a big distance that needs to be travelled.

 

 

Thanks!

[ak357 0]

What i'm trying to get done, is to have the camera feed into a dvr, and then into a axis 241q ip encoder, they will be probably 2 feet apart, so its not a big distance that needs to be travelled.

 

Thanks!

 

Then 1 IN 2 OUT Video Distributor that all u need

[Soundy 1]

You could try the T-adapter first, it may do just fine (you're not connecting to any consumer-grade gear, so the loading may be suitable). If the 50-cent fix doesn't work, then you can go for the $50 fix

[ak357 0]

You could try the T-adapter first, it may do just fine (you're not connecting to any consumer-grade gear, so the loading may be suitable). If the 50-cent fix doesn't work, then you can go for the $50 fix

 

Soundy

if you take your meter and measure video input resistance of any consumer or commercial piece of equipment

you will see 75 Ohm

[Angus 0]

Thanks for all the help, so i guess i would need at minimum 2 outputs and whatever inputs. Or can i use something like this in conjunction with the t-adapter?

 

 

http://cgi.ebay.com/4-4-4x4-Composite-BNC-Video-Booster-Extender-Amplifier-/360241333796?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item53e00e8624

 

 

or will that still give me bad results?

[bpzle 0]

We've used something like this one with good results. 1 input, 2 outputs. Dual voltage (24vAC or 12vDC)

 

 

 

 

 

Or you could go with a big monster like this one, 16 inputs to 32 outputs.

 

 

 

Of course, there's every size available in between too...