DVR not being able to record from b/w surveillance cameras

Discussion in 'General Electronics Chat' started by lighthouse, Jun 13, 2013.

  1. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    I own a DVR (emtec movie cube v850h) which can record from a composite video input. If I plug in a color surveillance camera, I can preview the video and record it with no problem, but If I plug in a b/w camera (CCIR) despite of being able to preview the image, when I try to record it it says "no signal".

    It happens with all b/w cameras, so I think my DVR doesn't like the b/w video levels or something and it doesn't detect the signal as a valid video source (but it previews it fine).

    Is there anything I can do? I use the DVR for surveilance and being able to record b/w signals is a must. Could it be a matter of adjusting the peak levels or something? I have basic knowledge of electronics.

    Any help would be appreciated.
    Thanks.
     
  2. Brownout

    Well-Known Member

    Jan 10, 2012
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    I would call the manufacture's customer service and explain the problem to them. If they can't help, return the unit.
     
  3. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    Thanks Brownout, I already did that. They replied to me that the unit works correctly with any standard composite video device. I've had the DVR for several years now and I can't return it... It's not a faulty unit, I suppose they didn't design it for b/w signals.

    I was just wondering if I could do something to de video signal so that my DVR likes it.
     
  4. Brownout

    Well-Known Member

    Jan 10, 2012
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    If they didn't design it for b/w signals, then they can't claim it works with any standard composite video device.
     
  5. PackratKing

    Well-Known Member

    Jul 13, 2008
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    Inexperience bids me ask... Are your BW cameras analog, trying to feed a DVR ?
     
  6. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    Yes, the camera has a composite analog output and it is connected to the composite video input. I have been using a color camera for some years now, but I need the b/w now because it has a higher sensitivity. There is no problem with the connection or the camera because my DVR previews the signal on TV with no problems.
     
    PackratKing likes this.
  7. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Also, color cameras in low light even with IR lighting comes out B/W. Does your recorder have a problem recording in low light?
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    You say you have a colour camera that works ok, what happens when that colour camera is in a low lighting condition does it go into B/W?
     
  9. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    With the color camera everything works fine, even in zero light conditions. It has nothing to do with the amount of light, but with the b/w signal itself. I tried two color cameras, and both of them worked, then with two b/w cameras and with both of them I got the "no signal" message when I tried to press the record button (despite of being able to see the image).
     
  10. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    A B/W camera uses the entire video bandwidth for Luma information so it can provide more detail but it's looks like the (cheap) designers of your media device decided skip the needed HW/SW for it.

    The why:
    The likely cause is that your DVR is looking for the Colorburst sub-carrier signal at 3.58mhz (NTSC). It uses that to phaselock the Chrominace subcarrier used to decode the Luma RGB information.

    Detailed information:
    http://www.eetimes.com/design/indus...nding-differential-gain-and-phase-Part-1-of-2
     
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  11. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    Thanks a lot nsaspook
     
  12. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Do you think he could get by with a RF modulator?
    http://www.radioshack.com/product/index.jsp?productId=2103095



    edit: probably not the answer, since he can watch the video without one, just cannot record..
     
  13. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    I tought about that, but my recorder doesn't have an analog TV input, just DVB-T

    Maybe a video sync regenerator would work...
     
  14. Ramussons

    Active Member

    May 3, 2013
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    Not necesary. Failure of Chrominance Sub Carrier (3.58 / 4.43) will not cause a failure of luminance. It will lead to Chrominance info (if any) being rejected and only a B&W picture being presented.

    Ramesh
     
  15. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    It will fail to record if the encoding chip or system has mandatory sub-carrier presence logic. I agree it should work as a general rule but maybe due to Macrovision requirements, incomplete register setup, this being a consumer level media and not a surveillance recording device they seem to have decided not to enable pure B/W signal composite inputs.

    B/W camera failure example (ColorSubcarrierLockStatus) -> http://e2e.ti.com/support/data_converters/videoconverters/f/376/p/40685/150215.aspx
     
    Last edited: Jun 15, 2013
  16. Ramussons

    Active Member

    May 3, 2013
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    Point noted :)

    Ramesh
     
  17. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    I finally found a workaround for my problem. I plugged the camera into the AV-in plug of an old VCR, and connected the AV-out of the VCR to the digital recorder. As it seems to work, I have unplugged the VCR heads motor to save energy and I use it only as a pass-through for the composite video signal.

    Thanks to all for the suggestions.
     
  18. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    :D
    Any loss of resolution?
     
  19. lighthouse

    Thread Starter New Member

    Jun 13, 2013
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    Not really, I even think the VCR amplifies the signal :)
     
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