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


  • Hi, thanks for your reply.

    I don't think this is noise generated from the Laserdisc player. I have a Crystalio II processor which uses the Texas Instruments TVP5160 3D comb filter and don't get any of these diagonal lines across the picture when using this unit.

    I need to keep the 3D comb filter turned on as it is an excellent filter and the sole reason I purchased this board.

    In the other thread the person said they:

    "I copyed SW driver registers for my system.  then, noise has gone."

    How would I do this too to check this isn't the problem?

    I will try and attach a picture of the lines but I can't seem to attach one from my phone.

  • 0
    •  Analog Employees 
    •  Super User 
    on Jan 26, 2017 11:49 PM

    There are 2 versions of the ADV7842-7511 eval boards.  If you look closely at the ADV7842 chip it will either be KBCZ-5 or KBCZ-5P.  The 'P' board is the keyless version.  The software between the two boards types operate slightly differently.

    The keyed version will, on power up, starts running the embedded codes, so for keyed version

    1) power up and configure everything to get video out.  Does the output have the interference?

    2) From terminal enter 'stoprep'.  This is stop the embedded code accessing the parts,  Does the output still have interference?  'startrep' will start the code running again.

    For the 'P' keyless part, the board expects scripts on power up however if you enter a 'startrep' from the terminal it will start running again.

    The script files are slightly different then the what the embedded code sets up the part as.  

    When AVES connects it sends a 'stoprep' command.  We don't want the script writes colliding with the embedded code writes.

    I'm am not exactly sure what 'downloading' the registers did.  Were they written back as a script???

    On a side note AvesBlue is replacing Aves.  You might want to check it out here

    AdvantivTm Video Evaluation Software (AVESBlue) 

    It works with the same folders

    Also I'd recommend using a USB to serial adapter, the USB connection is getting phased out.  But if what you have works than all is good.

    Let me know which version of the board you have and if starting or stopping the embedded code does.  

  • Hi,

    I'm using version EVAL-ADV7842-7511P with KBCZ-5P chip version. I currently don't have a USB to serial adapter but will have one tomorrow.

    Currently I am only connecting via USB. Is there a way to connect via Terminal with just the USB to issue commands? At the moment I am using only the AVES Blue software to run scripts.

    I have confirmed it is definitely the eval board causing these lines/noise as i get the same results when inputting from the composite out of a DVD player as well as the laserdsic player.

    Here is a photo of the issue. I am sorry it is quite difficult to make out because i had to capture the image from my iphone but the lines are very faint and go diagonally from bottom right to top left of the image and are moving/scrolling.



    When I receive the USB - Serial cable tomorrow I will try running 'stoprep' In terminal as you suggest to see if that changes anything.

    Thanks for all your help with this.


  • 0
    •  Analog Employees 
    •  Super User 
    on Jan 27, 2017 6:23 PM

    You can connect to the ports via a terminal emulator.  We use TeraTerm set for 115kbaud, 8bit no parity.  All commands are just plain ascii text strings.  Enter 'help' to get the list.

    The -5P board does not start the repeater software at power up.  It was meant to be script driven.  You can enter 'startrep' to get it going.

    I'm not sure what's really going on here.  We don't see those type of lines.  The UK is a 50Hz country, I am wondering if there is some kind of beat frequency going on since you see the same problem with a DVD player.  Can you do a quick check with all the lights off in the room.  LED and fluorescent lamps can sometimes flicker at the power frequency.  The eye doesn't see it but a beat frequency between the TV and lamps might introduce weird line.  This is just a quick and easy check to rule that out.

    Also you say the the lines aren't there when the 3D comb filter is turned off.

  • Hi,

    So having purchased the USB-Serial cable and issuing commands via TeraTerm, the lines interference has completely disappeared! Thank you so much for walking me through this! The decoding quality on this board is the best I've seen. Extremely impressed.

    Is there a way to save a state for the Eval board so that it starts up with CVBS input selected as default without the need to connect it to a PC?

    Many thanks again