[sdiy] FPGA Madness? (Was: NCO Jitter)

Scott Gravenhorst music.maker at gte.net
Sat Aug 4 15:06:58 CEST 2018


Michael Zacherl <sdiy-mz01 at blauwurf.info> wrote:
>
>> On 4 Aug 2018, at 06:38, Scott Gravenhorst <music.maker at gte.net> wrote:
>> 
>> but I did it the "wrong" way by making an FIR filter with a
>> huge kernel.  The filter did the job to remove most of the alias artifacts, but it
>> did some weird frequency dependent amplitude things especially at the high end of the
>> audio spectrum.  I later learned that it is better to use cascaded smaller kernel
>> filters,
>
>Hi,
>
>“kernel” == order of the filter? 
>
>m.

Sorry, I neglected to state that the filter is a FIR type.

FIR filters have a kernel of coefficients which define the impulse response.  The larger the
kernel, the more definition one can have in the output spectral profile.  Larger kernels also take
more time to compute which is a drawback of the FIR filter.  FIR filters can make good brick wall
filters, that is, very flat response with steep roll off into the stop band.

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- http://scott.joviansynth.com/
-- When the going gets tough, the tough use the command line.
-- Matt 21:22



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