[time-nuts] Sub Pico Second Phase logger
Tom
scopefreak at onsnet.nu
Fri Dec 19 10:08:30 UTC 2008
On Friday 19 December 2008 02:46, Joe Gwinn wrote:
> > >> 10Hz resolution whilst avoiding phase truncation spurs is
> > >> impractical
> >>> with a DDS chip by itself.
> >>> Depending on the DDS and its clock frequency, the frequency
> >>> spacing of phase truncation spur free outputs may be as large
> >>> as several kHz.
> >>
> >> Is this true of concatenated DDS chips? I recall a patent to
> >> the
> > > contrary.
> >
> >Which patent?
>
> Hmm. It's at work. I'll look it up in January. As I recall, the
> second DDS made a small integer conversion, and so had low spurs,
> while the first DDS was set to whatever was needed.
>
I think you are referring to patent 5598440 about a DDS driven DDS.
Tom
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