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1452 ASRC noise

zhou
on Dec 17, 2014

Hi,
   I use 1452 on my target broad.The testing project of ASRC is attached.When I need the input from ADC ,I set the gain of ASRC to be  -100dB and the gain of ADC to be 0dB. When I need the input from ASRC ,I set the gain of ADC to be -100dB and the gain of ASRC to be 0dB. It is OK if I change the settings(change the gain of ADC and SPDIF) after I connect the optical output of DVD to the SPDIF pin. But if I change the settings(change the gain of ADC and SPDIF) before I connect the optical output of DVD to the SPDIF pin, when I change the settings(change the gain of ADC and SPDIF) it generates a noise which sounds like "POP". Do I miss any setting of ASRC or SPDIF? Or it is the bug of 1452?

Best Regards,
Alex

attachment.zip
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  • 0 on Nov 19, 2015 5:48 PM over 5 years ago

    Hi Dave,

    this is not a solution for the first lock after powering up the ADAU.

    There is no problem with the mute function (mute ASRC when lock is lost) if at least one lock is done!

    After this you can plug-in/out the toslink without any pop noise. You can also reset the ADAU (ADM811), and hotplugging spdif after this without any noise.

     

    Cause it is a one time event there is a solution without a uC.

    The signal level of ASRC without at least one lock is undefined, a level detector shows something like this (static):


    So, after some thoughts on this problem..

    The first lock always ends up in FS signal peak, and I have never seen a (random?) default signal >-3dB.

    So I just detect the lock peak signal one time.

    Maybe AD is able to implement a defined status of the ARSC, but for now - this is even the same solution for the problem with I2S pop noise on first lock event if you have to use an ASRC.

    Lasse

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  • 0 on Nov 19, 2015 5:48 PM over 5 years ago

    Hi Dave,

    this is not a solution for the first lock after powering up the ADAU.

    There is no problem with the mute function (mute ASRC when lock is lost) if at least one lock is done!

    After this you can plug-in/out the toslink without any pop noise. You can also reset the ADAU (ADM811), and hotplugging spdif after this without any noise.

     

    Cause it is a one time event there is a solution without a uC.

    The signal level of ASRC without at least one lock is undefined, a level detector shows something like this (static):


    So, after some thoughts on this problem..

    The first lock always ends up in FS signal peak, and I have never seen a (random?) default signal >-3dB.

    So I just detect the lock peak signal one time.

    Maybe AD is able to implement a defined status of the ARSC, but for now - this is even the same solution for the problem with I2S pop noise on first lock event if you have to use an ASRC.

    Lasse

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