Sample rate independent-module (SigmaStudio)

Farhad,

Any parameters that are related to time or sampling rate will be be affected if you change the sampling rate (fs) from 48 kHz to 96 kHz. The filter coefficients have to be changed when fs is changed because their calculation includes fs. Other parameters, such as a compressor's hold, decay, and rms time constant, will be affected by fs. For example, doubling fs will mean that these coefficients have to be effectively cut in half to provide the same response over a fixed time.

Parameters that are not time dependent, such as a mixer's gain or a volume control, will not change with fs.

When you change the fs in your SigmaDSP, you should be resetting the IC and rebooting its program and parameters because it's implied that your master clock is also changing. We can't guarantee the smooth operation of the PLL when the master clock frequency is changing. If you need your IC to run continuously with changing fs, then I'd recommend you look at using an asynchronous sample rate converter (ASRC) to keep the SigmaDSP always running at a constant fs. Some SigmaDSPs, such as the ADAU144x family, include integrated ASRCs. ADI also has stand-alone sample rate converters like the AD1895 that can be used to convert sample rates over a wide range with greater than 120 dB dynamic range performance.

Jerad

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Thank you,
EZ Admin