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Title: DSD to PCM Conversion - roll off filter
Post by: dtc on November 07, 2014, 10:46:26 PM

I am converting from 5.6 MHz DSD to 192K PCM. In some software there are options to apply optional roll off filters to remove high frequency noise. Does VS apply such a filter? If so, what are its characteristics? Does it vary by PCM output sampling rate?

Thanks.

Tom

Title: Re: DSD to PCM Conversion - roll off filter
Post by: Paul Sanders (AlpineSoft) on November 07, 2014, 10:50:45 PM

Hi,

It rolls off at 48 kHz for DSD standard rate and 96 kHz for DSD double rate. Any higher and you get a lot of noise in the converted signal.

Title: Re: DSD to PCM Conversion - roll off filter
Post by: dtc on November 07, 2014, 10:59:41 PM

So basically at the Nyquist frequency for the sample rate, If I am going form2xDSD to 192K sample rate, it starts rolling off at 96 KHz. What is the roll off rate, just for curiosity.

Title: Re: DSD to PCM Conversion - roll off filter
Post by: Paul Sanders (AlpineSoft) on November 07, 2014, 11:03:47 PM

It's pretty steep. I'm not sure exactly what it equates to but we use a 96 pole FIR filter which was designed to have a reasonably sharp cutoff with good rejection above the cutoff frequency.

Title: Re: DSD to PCM Conversion - roll off filter
Post by: dtc on November 07, 2014, 11:14:06 PM

Thanks. Clearly I am not going to hear anything above that :)

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Forum List => Technical Support => Topic started by: dtc on November 07, 2014, 10:46:26 PM