Re: [soft_radio] Re: DDS + PLL to clean up spurs?

Thu, 26 Jan 2006 18:12:02 -0800

so you get crab grass instead of saplings

KD5NWA <[EMAIL PROTECTED]> wrote:
It increases the noise floor of the output which causes all the
things you mentioned, but the spurs are gone, no a whole lot of consolation.

I'm not recommending doing it, it's just a strange quirk of DDS
technology, some uses that require no spurs but doesn't care too much
about close in phase noise could use the trick.

When you look at graphs with it and without it, you initial though is
wow all the spurs are gone, later you notice the noise floor went up
10dB to 20 dB, not so good.

At 06:22 PM 1/26/2006, you wrote:

>--- In [email protected], KD5NWA <[EMAIL PROTECTED]> wrote:
> >
> > Here is another item that will tweak your sense of reason.
> >
> > A DDS can have all of it's spurs cleaned up if when you take the sine
> > wave value out of it's lookup table and add a small random number to
> > it, then that value is sent to the DAC and output.
> >
>Wouldn't that also greatly increase the phase noise and kill the close
>in receiver performance?
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>
>--
>No virus found in this incoming message.
>Checked by AVG Free Edition.
>Version: 7.1.375 / Virus Database: 267.14.23/240 - Release Date: 1/25/2006
>
>
>
>
>--
>No virus found in this incoming message.
>Checked by AVG Anti-Virus.
>Version: 7.1.375 / Virus Database: 267.14.23/240 - Release Date: 1/25/2006


Cecil Bayona
KD5NWA
www.qrpradio.com

"I fail to see why doing the same thing over and over and getting the
same results every time is insanity: I've almost proved it isn't;
only a few more tests now and I'm sure results will differ this time ... "


--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.1.375 / Virus Database: 267.14.23/240 - Release Date: 1/25/2006





SPONSORED LINKS
Ham radio Craft hobby Hobby and craft supply
Icom ham radio Yaesu ham radio

YAHOO! GROUPS LINKS



Reply via email to