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

[Tim Ressel]

Okay, that was silly. I would need mondo processor power to do that. 
Looks like its FPGA time! Yay!  I like Xilinx so the questiob becomes 
how much FPGA do I need? Spartan-6?

--timmers


On 8/4/2018 9:14 AM, Tim Ressel wrote:
>
> Thanks everyone! It looks like the FPGA route is doable, although 
> those CIC filters make me think I can do this on a processor after 
> all. Maybe 2 procs: one for handling MIDI and ADC tasks, and one as a 
> oscillator core. Use SPI to write values to the osc core. NCOs are 
> cheap so doing 9 instances is no problemo. I need VCAs on each NCO but 
> that is just a multiply. That might just work.
>
> --timbo
>
>
> On 8/4/2018 6:06 AM, Scott Gravenhorst wrote:
>> 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
>>
>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>
> -- 
> --Tim Ressel
> Circuit Abbey
> timr at circuitabbey.com
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20180804/b14de6f6/attachment.htm>