EVAL-ADV7842-7511 Noise Interference lines

Hi, I have a EVAL-ADV7842-7511 Board which I'm using to decode CVBS signal from a Laserdisc player.

I have an issue where I'm seeing faint diagonal lines across the image. These are present on all of the input formats 10Bit, 24Bit and 36Bit and is also present on the s-video input. 

It it looks almost like interference. I've tried multiple cables and players and all produce the same results.

Any idea what is causing this?

many thanks

ken

  • I'm using the AVES3 software connected via USB and running the input selection scripts from the folder here: AVES3_Folder_EVAL-ADV7842-7511.zip

    i haven't changed any other registers that I'm aware of.

    all software im using I downloaded from this link:

    AdvantivTm EVAL-ADV7842-7511 Video Evaluation Board 

  • I will confirm this but I believe they are static. Thin transultant diagonals. They are also not consistent and change in severity as I switch between input standards (10Bit, 24Bit, 36Bit) but it appears it's the switching of the input standard which Can affect it and not the specific input standard itself. 

  • Also this could be completely coincidental that changing the input has an effect. All I know is that sometimes the lines are more noticeable than other times. Can't lock down what makes them more or less severe.

  • So having done more tests and to answer questions above the lines are moving. They also disappear completely if I run the input script:

    Scripts 7 Simultaneous mode

    7-1a Port A, CVBS out through HDMI With HDMI Audio (PCM)

    However with this profile appears to disable the 3D comb filter. Could the lines I'm seeing be an issue with the 3D comb filter? I found this thread

    https://ez.analog.com/message/68430?commentID=68430#comment-68430 

    which sounds like a similar issue but I don't understand what the "SW driver REPEATER" is or where to find it. Can anyone point me in the right

    direction? Apologies at my lack of knowledge here. Any help would be much appreciated.

    Kind regards

    Ken

  • 0
    •  Analog Employees 
    •  Super User 
    on Jan 26, 2017 6:15 PM

    The ADV7842 was originally designed to handle VCR outputs.  Your laser disk player pre-dates VCRs.  The laser disk player might be generating some kind of noise which will not show on composite TVs of their day.  The 3D comb filter might extenuate this noise to the point where it can be seen on today's high quality TVs.

    The TBC option was designed to handle frame timing jitter issues VCRs had.

    It's OK to turn off TBC and 3D comb.  

    The SW repeater is embedded code that configures the operation of the board.  In HDMI definition 'repeater' is a function that handle EDID reads from the sink and forwards them to the source.  It also handles all the HDCP requirements of moving keys up stream.  The eval board you have allows you to override the repeater code with scripts.

    Your laser disk player is composite only so you don't have to worry about HDCP keys.