[time-nuts] spur prediction DDS software

Brian Davis brimdavis at aol.com
Fri Jan 28 00:16:56 UTC 2011


Luis Cupido wrote:
>
>Is there a DDS spur prediction software around ?
>
>I mean for an arbitrary DDS design, like I would
>implement with logic or fpga etc.
>
 That <dds_oddities.pdf> file I linked to yesterday has a
couple references on page 4:

- Martin Pechanec’s MATLAB scripts ( mentioned earlier by Jim L. ),

- Zs. Pápay’s website and Mathcad files:
  http://www.hit.bme.hu/people/papay/sci/DDS/simul.htm

  I'd second Jim's suggestion of trying the Matlab scripts in Octave,
I'd guess that  the numerical sections would port easily but the
GUI stuff might need some rework.

  There's also a Mathcad-like free program called SMath Studio
( which I haven't actually used yet ) that might prove useful to try
setting up a model similar to those done in Mathcad.

  Note that the close-in phase truncation stuff discussed earlier
has a very long repetition period, so for big phase accumulators
you need either a huge FFT time record to see the phase truncation
rollovers, or else use a shorter FFT record and preset the phase
accumulator to a value shortly before the rollover.

Brian



More information about the time-nuts mailing list