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Chroma PM noize for ADV7180 and ADV7343

Hi,

My customer has a question for ADV7180 and ADV7343. When they use these device and pass through the video data at 656 format, PM specification of Chroma noize was not good.

It can see around 35dB to 45dB. they can see AM spec is good (it can see around 55dB to 65dB). Even if they enabled SFL signal, this value was not changed. Also, even if they improved power stability, the result was not changed.

At competiter chip, they can see good performance (it can see around 55dB to 65dB at both of PM and AM spec).

Do you have any solution for the improvement of a noize spec? or do they need any register setting?

Regards,

  • Hi,

     ADV7180 is a 2D comb decoder and the artifacts are a result of that combing process (luma-chroma seperation). To remove them completely you would have to a 3D comb solution such as the ADV7800.


    Note that the ADV7180 requires a 28.63636 MHz crystal clock with an accuracy of 50ppm.

    The line locked clock (LLC) output from the ADV7180 is 27MHz +/- 5%. The LLC varies to compensate for horizontal lines of analog video that are longer/shorter than standard.

    The artifacts around the writing in the image above are unfortunately standard for the ADV7180. These are luma/chroma separation artifacts.  The ADV7180 is designed to have minimal latency delay so it has a 2D comb luma/chroma separation filter. This unfortunately will result in artifacts.  

    It is possible to get better performance by using a part that has a 3D comb luma/chroma separation filter such as the ADV7850. This will result in significant latency delay and extra cost.

     

    Thanks,

    Poornima