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Door Entry Phone

Discussion in 'General Electronics Discussion' started by R791945, Aug 21, 2018.

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  1. R791945

    R791945

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    Jun 19, 2015
    In our block of flats there are 7 analogue, audio only door entry phones. There are enough free wires in the telephone cable to add video without rewiring.

    It was put to me that it would be a waste of money to rip out the DEPs and replace them with digital and was happy to hear this. I suggested that in order to add video that the we have each flat supplied with small flat led screens, independent of the existing audio system, and take the feed from the security camera at the front door, via the DVR's outputs. I do not want to use wifi as the connection but want a wired connection. The engineer told me for that to work, each phone would need an amplifier which if true would lead to an expensive installation as each amplifier would cost £120. Is the engineer's advice correct?
     
  2. kellys_eye

    kellys_eye

    4,275
    1,146
    Jun 25, 2010
    Assuming the cabling can carry a video signal are you talking baseband video or RF video?

    If baseband video then you may need a video splitter/amplifier to drive each line but not an amplifier per flat.

    What, precisely, is the cable being used? Multi-pair (twisted)? Coaxial?

    A wi-fi solution may be the only solution if the cabling isn't up to the bandwidth/crosstalk requirements for BB video.
     
  3. R791945

    R791945

    78
    0
    Jun 19, 2015
    Thank you for your reply.

    I hope this is a helpful response about the video signal

    Video Signal
    The video monitor ie the DVR has the following outputs:
    1-ch PAL/NTSC, BNC (1.0VP- P, 75Ω) composite video signal output.
    1-ch VGA output.
    1-ch HDMI output.
    Support TV/VGA/HDMI video output at the same time.

    Interface
    2 USB 2.0 ports.
    RS485
    PTZ control port
    Support various PTZ control protocols

    No RS232

    The cable seems to be multi core telephone cable
     
  4. kellys_eye

    kellys_eye

    4,275
    1,146
    Jun 25, 2010
    Sending the PAL/NTSC composite video over twisted pairs may work but this will require a pair that runs to each destination.

    A lot depends on how the original system worked - are there separate cores in the cable for each flat? How many cores per flat?

    What form of control do you need to maintain? Having a 'call' signal, an 'open' signal, audio?, video (which is what you're wanting) will require either individual control lines from each flat or some form of multiplexing.

    If you don't have the relevant cores available per flat then multiplexing is the only way to go and that's a whole different prospect for installation.

    Do you have any technical spec, schematics etc for the system currently in use?
     
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