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Distortion with ASRC input on ADAU1445

Question asked by RyanJ on Jul 11, 2012
Latest reply on Jul 20, 2012 by RyanJ

I am experiencing noticeable distortion when using an synchronous input on the 1445. I used a logic analyzer to capture the samples going to the 1445 and verified that they are pure (I'm using a canned 1kHz digital tone in the processor feeding the asynchronous samples). The 1445 is running at 48kHz and the samples are arriving at 44.1kHz


Below is a capture of the signal from the 1445 (through a DAC) when using the asynchronous tone. Note the strong spurs ~36dB below the fundamental:

ASRC 1kHz Tone.png


This is a capture when generating the tone within the DSP itself. Noise is ~72dB below the tone.

DSP 1kHz Tone.png


Any thoughts as to the cause of this? Thanks,

-- Ryan