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

[Bruce Griffiths]

Another description of such artifacts occurs in the tutorial:
http://www.analog.com/static/imported-files/tutorials/450968421DDS_Tutorial_rev12-2-99.pdf

Bruce

Gerhard Hoffmann wrote:
> 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)
>
>
They've changed their name to
http://www.wirelessinnovation.org

However finding that paper may take a while.
> 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.
>