ADV7183B Question

We have a customer using one of our older systems and it is having a problem with their video signal. Picture 20140430_153250… shows what the video should look like at the output of the system.  Output.jpg is what is coming out of the system.  The remaining pictures are from the scope showing the actual video signal from the customers system. The pdf file is the page from our schematic.
 
To give you a system level perspective, the video is input to a box of their design which overlays the text on the video and then outputs it to our box. If the overlay is skipped, it works fine. So it is obvious that the overlay is the problem. The scope shots are for the video during the overlay period. There is some obvious distortion to the horizontal sync pulse.
 
What we are interested in is if there is any way we can correct for this in the ADV7183B using software settings. Beyond that, is there something we can do in our hardware to correct for this? The customer has not changed their hardware in 10 years and they claim it works with other equipment. In fact the very first image was captured using a StarTech USB Video Capture Cable (SVID2USB2). So we know there is something out there that can decode this video.
 
A quick response to this is greatly appreciated.

attachments.zip
  • This questions was posted on my behalf by my local Arrow FAE. It is missing one last picture. That pictures shows the resulting output from the ADV7183B system. I have attached that picture to my post.

  • 0
    •  Analog Employees 
    on May 2, 2014 9:14 PM over 6 years ago

    So the system looks like:

    camera -> overlay box -> AD7183B -> monitor/capture   has problems

    camera -> ADV7183B -> monitor/capture works OK

    Horizontal pixel placement is based on the falling edge of the sync pulse.  RS170_1 has sharp edges while RS170_2 has sloped leading edges.  I'd first figure out why we have sloped edges.

  • Hi,

    Your system assumption is correct. Our box actually does video compression and we have isolated the "problem" to it. I would like to know what they are doing to the video as well. Unfortunately I don't have access to our customer's equipment. Even if I did I doubt they would allow me to poke around inside their box. Even if I knew what they were doing, I don't think they are going to fix it. This has "worked" for the past ten years. I have all of the information I'm going to get from them. The interesting thing is both RS170_1 and RS170_2 are the same signal, just different lines of the video. _1 is the image and _2 is the their overlay. Is there some way to get the 7183 to sync to the rising edge of the sync pulse?

  • 0
    •  Analog Employees 
    on May 2, 2014 11:09 PM over 6 years ago

    Can't really get it triggered on the rising edge, beside if you did then the entire image would shift to the left. Their overlay box has poor sync edges.  Something changed from now and 10 years ago.

    NTSC has specific rise and fall times on the sync pulse and they're not meeting it.  By spec sync edge should be < ~140ns.

    Image _1 comes from the good section of the screen while image _2 comes from the overlay section.  Makes sense.

  • 0
    •  Analog Employees 
    on Aug 2, 2018 2:39 PM over 2 years ago
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin