Didier Stevens

Monday 22 August 2011

Quickpost: CCTV Over UTP

Filed under: Hardware,Quickpost — Didier Stevens @ 0:04

I knew it was possible to transmit a composite video signal over UTP, but I always assumed that this was a kludge: that the preferred way was to use RG59 cable.

But recently I discovered that UTP cabling is often used in professional CCTV installations, because it offers the same benefits of structured cabling (like standardization and cost reduction).

To send the video signal over UTP, you need video baluns (one at each end of the pair). It is not transmitted via Ethernet, but the video signal is transformed to be send over a pair. Since CAT5 cable has 4 pairs, you can send 4 video signals over 1 cable. That’s what I’ve done at home, to limit the number of cables I had to install.

You can also use some pairs in the CAT cable to provide power to the CCTV camera (typically 12V) or to transmit audio (when you add a microphone to your CCTV camera). Video baluns are passive components, they don’t need power to operate. I’ve used baluns to cover distances of about 30m, and I don’t notice a difference in the quality of the video signal (compared to a video signal transmitted over RG59 cable).
Most baluns advertise distances of several hundred meters.

I was also able to transmit a video signal without noticeable quality degradation over an untwisted pair of 10m.


Quickpost info


3 Comments »

  1. Most of the cameras I’ve installed have been from Ganz and Level One, and I think almost all of them have the UTP balun built-in. You’ll often find screw-down terminals as well as some kind of video connector. I’m rather fond of PoE IP cameras because you can run the switch and DVR off of a centralized UPS, but a lot of times, it comes down to budget, cabling logistics and what kind of DVR you want (or already have)

    Comment by ax0n (@ax0n) — Monday 22 August 2011 @ 14:11

  2. @axon Those are professional IP cameras?

    Comment by Didier Stevens — Tuesday 23 August 2011 @ 10:06

  3. The Ganz cameras have all been dumpster finds requiring various repairs (like broken-off chip capacitors) – They’re not IP cameras, but they’re professional grade indoor cams, given that the dumpster I keep fetching them out of belongs to a prolific security and services vendor that recently ran into trouble in the polling machine debacle. I’m always finding little dome cams, though, similar to this one: http://www.h-i-r.net/2009/03/ganz-dome-security-camera-refurb.html

    The POE IP cameras I’ve dealt with have been geared towards SMB. One I have at my desk has screw-down terminals, but taking a close look, it’s a NC, Common and NO connector for triggering something if it detects motion, not A/V. Analog A/V out is a 1/8″ TRS (like a headphone jack) with a pair of RCA male ends on the adapter cable it shipped with. So, I’ll be darned, I’d need a balun for this one.

    Comment by ax0n (@ax0n) — Wednesday 24 August 2011 @ 19:10


RSS feed for comments on this post. TrackBack URI

Leave a Reply (comments are moderated)

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

The Rubric Theme. Blog at WordPress.com.

Follow

Get every new post delivered to your Inbox.

Join 236 other followers

%d bloggers like this: