[time-nuts] An (unknown?) nasty feature of the DDS principle for time nuts applications

[Gerhard Hoffmann]

Am 25.01.2011 15:35, schrieb Ulrich Bangert:
> see page 8.6ff of the service manual to see that the HP3325 is not DDS based
> but uses a "Fractional N Synthesizer scheme" which is something completely
> different and is not prone to the described effects.
Yes, it's f-N, I must have stored that in the wrong winding of my brain...
Fortunately, I had no need to repair my 3325B upto now.

BTW, your effect has been described in detail in the article that
Bruce cited on jan7 in the NoStateOfTheArtCounter thread.

<http://sdrforum.org/pages/sdr06/sdr06_papers/1.3/1.3-01.pdf >
(seems not to work anymore, may be a typo of mine)


In the meantime, I have published my sin/cos table on

http://opencores.org/project,sincos

It should be easy to generate a version with BCD-coded phase input
to make a decimal-friendly DDS.