Hi The loop bandwidth needs to be quite wide while you are switching. Once you are done with the "move" you can shrink the bandwidth quite a bit.
Depending on what you are trying to do, that may or may not help ... Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Luis Cupido Sent: Thursday, October 15, 2009 10:21 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] fast freq. synthesis schemes My fear is "in the loop bandwidth" is a lot of BW as I need a wide loop for it to be fast. Okay, it sounds a nice path to investigate. tks. lc Lux, Jim (337C) wrote: > > > On 10/15/09 5:56 AM, "Luis Cupido" <[email protected]> wrote: > >> Hi Bert, >> >> Thanks for the input. >> >> briefly; >> -Phase noise is not too important >> -It is to make just a few (and cost is not a major issue) >> >> The suggestions using prescalers or any other high speed >> digital chips may bring simplicity while compared with >> the design using multiple loops and harmonic mixers and samplers >> that is something I had in mind when I place the question out. >> I was wondering if recent technology would make possible >> to have a simpler approach. >> >> I like your first suggestion but I fear the spurious... >> I have no clue how bad it will be, but I guess I can only >> be sure if I make a prototype of that. >> The second one I must check how small would be the step... >> 1 MHz would be enough for a start. > > The spurs might not be as bad as you think... The newer crop of DDS include > some forms of error cancellation for close in spur reduction, so the "in the > loop bandwidth" part is cleaner. Also, maybe you can use clever choice of > DDS clock rate to make sure that you only need "nice" phase increments that > evenly divide into the lookup table length. > > > > > _______________________________________________ > 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. _______________________________________________ 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.
