Hi On Oct 8, 2014, at 3:52 AM, Hal Murray <[email protected]> wrote:
> > [email protected] said: >> Kratos (www.kratosepd.com) do fast switching synthesiser subsystems that >> can be locked to a reference.. > > What does "fast switching" mean in the context of a DDS? Not much at all. Your DDS clock will be something like 1 GHz and it will “switch frequency (actually it switches phase)” on a clock edge. You probably can’t load a billion updates a second through the update port. People do indeed load millions of updates a second.The DDS is quite happy to “follow” the updates. It’s one of the ways to get a clean(er) 10 MHz reference signal out of a DDS on a GPSDO. > > What does the spectrum of a DDS look like if I switch back and forth between > 2 frequencies at 1 KHz? Since it is phase coherent FSK with instantaneous phase change, it’s pretty much a textbook spectrum. Lots of energy at the switch points. It’s likely closer to the textbook than anything you can get out of a conventional (non DDS) signal generator. > Or what question should I be asking? Is that waveform (and it’s spurs) OK in the application or not. Only Jim knows for sure … Bob > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
