I'm trying to use the S/PDIF input and output on the ADAU1401A-EVAL board, running at a 192kHz Sample Rate.
I've got the system working with slower sample rates (48, and 96 kHz specifically), however when I use 192kHz I get a very strange frequency response, almost like a weird aliasing artifact.
I've attached my project and examples of the distortion. The project is setup to do just a straight passthrough from the inputs to the outputs. I've gone through and set the switches and jumpers as described in Table 7 of the Eval Guide.
20hz-96khz Freq Sweep 192khz Fs.bmp shows the output as level vs. frequency for a 20-96Khz frequency sweep. That should be a straight line (See 20hz-64khz Freq Sweep 128khz Fs.bmp for expected output).
64Khz Input Tone at 192khz Fs.bmp shows an FFT of the response to a 64 kHz input tone.
64Khz Input Tone at 128khz Fs.bmp shows an FFT of the response to an 64 kHz input tone sent by a generator running at 128 kHz Fs.
I'm using an Audio Precision to generate (and analyze) sample tones encoded as 24 bit S/PDIF over coaxial cable.
Any suggestions for ironing this out?
Thanks in advance.