Re: [time-nuts] AD9913 programmable modulus DDS. was: Re: An (unknown?) nasty feature of the DDS principle for time nuts applications
In message <4d3f06ca.8020...@karlquist.com>, "Richard (Rick) Karlquist" writes: >What you need is the AD9913. It has a programmable modulus. >Now you're not stuck with 2^32. You can pick any convenient >value. Isn't it more like M/N applied to DDS, than a variable MODULUS ? As far as I know the sine lookup-table is always modules-2, isn't it ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] AD9913 programmable modulus DDS. was: Re: An (unknown?) nasty feature of the DDS principle for time nuts applications
Since the 9913 lacks a means of low pass filtering the DAC reference it may well suffer from significant AM noise sidebands. With a well designed sine to square converter as required when using it as part of an offset source like that outlined in Rick's paper (probably desirable to reduce the phase noise floor of the offset source) this characteristic shouldn't be a significant issue. Bruce Richard (Rick) Karlquist wrote: What you need is the AD9913. It has a programmable modulus. Now you're not stuck with 2^32. You can pick any convenient value. Rick Karlquist N6RK On 1/25/2011 5:37 AM, Ulrich Bangert wrote: Gentlemen, the pros and cons of DDS chips and how to improve them have been discussed here from time to time. Most of the improvements have the aim to remove spurs out of the power spectrum or to reduce the noise level. Yesterday I run into a thing that may make it very qestionable whether DDS based circuitry is in general good for precise timing applications. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] AD9913 programmable modulus DDS. was: Re: An (unknown?) nasty feature of the DDS principle for time nuts applications
What you need is the AD9913. It has a programmable modulus. Now you're not stuck with 2^32. You can pick any convenient value. Rick Karlquist N6RK On 1/25/2011 5:37 AM, Ulrich Bangert wrote: Gentlemen, the pros and cons of DDS chips and how to improve them have been discussed here from time to time. Most of the improvements have the aim to remove spurs out of the power spectrum or to reduce the noise level. Yesterday I run into a thing that may make it very qestionable whether DDS based circuitry is in general good for precise timing applications. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
