Re: OT: baseband video splitters

Bill Wright wrote:
In the CCTV industry (or it least in its lower regions) it is standard practice to use BNC T pieces to derive two feeds from one camera. This has always seems a bit dodgy to me. What about mismatch? What about reflections if the ends of the cables aren't accurately terminated?

It's always bothered me but it has arisen more forcibly in my mind because of the following. I have been asked to add camera signals to two of my UHF distribution systems as extra channels. This is commonly done, and the usual method is to take a feed from the 'video out' BNCs on the HDD recording device. There is normally such a socket corresponding to each camera input. In these two cases however the recorders also record audio, and the manufacturer has used the BNCs that were previously 'video out' for 'audio in'. When I asked the CCTV company what they intended to do to give me my baseband video feeds they said "Oh we'll fit T pieces on the camera feeds." I would have thought they should be using a small one in/two out amplifier.

I wonder if anyone could make a few general comments about this. Has anyone other experience of this? I wonder what the attitude to splitting video signals without any sort of matching device is in other industries.

NEVER, NEVER, NEVER !

You should always use a DA, there is no satisfactory passive alternative with baseband video. Using a T-piece is a dreadful bodge, you'll get ringing and all sorts of nasties. At best you'll end up double terminating the signal, reducing its amplitude by 6dB on both legs.

CPC sell video DAs, a basic one 25-35 quid should be fine for CCTV use. See the CPC 2006 Catalogue, pages 57 to 59


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Mark
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Relevant Pages

  • OT: baseband video splitters
    ... practice to use BNC T pieces to derive two feeds from one camera. ... I have been asked to add camera signals to two of my UHF ... manufacturer has used the BNCs that were previously 'video out' for 'audio ...
    (uk.tech.digital-tv)
  • Re: OT: baseband video splitters
    ... I have been asked to add camera signals to two of my UHF distribution systems as extra channels. ... In these two cases however the recorders also record audio, and the manufacturer has used the BNCs that were previously 'video out' for 'audio in'. ... When I asked the CCTV company what they intended to do to give me my baseband video feeds they said "Oh we'll fit T pieces on the camera feeds." ...
    (uk.tech.digital-tv)
  • Re: OT: baseband video splitters
    ... I have been asked to add camera signals ... 'video out' BNCs on the HDD recording device. ... to give me my baseband video feeds they said "Oh we'll fit T ...
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