The spurs you see are real. They are DDS spurs for the most part. The traveling hump is due to the switching power supplies providing the rails on the INA's.
The DDS spurs can and should be avoided. We can mathematically derive where they will be and then we can avoid them. It is yet another example of how sweet this software defined thing is. The tremendous dynamic range of the AGC allows you to hear the weak ones but even these can be avoided. Furthermore, except for the direct clock submultiple leakages, such as around 50 MHz, none of them are large enough to cause reciprocal mixing so just by avoiding them, we can leave their impact behind. What the volunteers need is a few more volunteer coding hours to fix it. Bob N4HY Maarten N1DZ wrote: > I disagree. With my SDR1000 the spurs are real, audible and numerous > within the receivers passband. > Maarten N1DZ > > On Mon, 14 Aug 2006 23:53:16 -0400, Dudley Hurry <[EMAIL PROTECTED]> > wrote: > > >> I guess the key word here is "see". Only in the SDR can you see the >> spurs, even if you can't hear them.. Most of the spurs I see, are gone >> by the time they arrive in my passband. Any radio will have some >> spurs, but they only worry about the ones that can be heard. I'm sure >> that >> the SW can be taylored to eliminate all the spurs, but I am not sure that >> you could afford to run the computer that would be fast or big enough to >> run it.. >> >> 73, >> Dudley >> WA5QPZ >> >> >> >> >> >>> On Mon, 14 Aug 2006 12:20:59 -0400, Richard Smith <[EMAIL PROTECTED]> >>> wrote: >>> >>> >>>> I'm new to the SDR-1000 and have a question about spurs. I've read >>>> >>> the >>> >>>> reflector, and understand that right now, spur reduction has more to >>>> >>> do >>> >>>> with moving the spurs out of the filter passband as opposed to >>>> eliminating them. However, on the quiet upper bands with very low >>>> >>> noise >>> >>>> floor, I see serious spurs on the panadapter as I tune across the >>>> >>> band. >>> >>>> I can often hit frequencies where the entire spectrum lights up like a >>>> picket fence and includes spurs within the filter passband as well as >>>> across the rest of the 48 kHz of spectrum. On the lower frequency, >>>> noisier bands, I notice similar behavior with no antenna, but don't >>>> notice the spurs in normal operation once the antenna is connected and >>>> the noise floor comes up. Is this normal, or do I have a problem with >>>> my SDR-1000? Short of the brute-force algorithm that has been >>>> >>> discussed >>> >>>> for taming the DDS, is there anyway to fix this abnormal looking >>>> behavior? >>>> >>>> Thanks. >>>> >>>> Rich W1EZ >>>> -------------- next part -------------- >>>> An HTML attachment was scrubbed... >>>> URL: >>>> >>>> >>> /pipermail/flexradio_flex-radio.biz/attachments/20060814/a548ca48/attachment.html >>> >>>> _______________________________________________ >>>> FlexRadio mailing list >>>> [email protected] >>>> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >>>> Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >>>> FlexRadio Homepage: http://www.flex-radio.com >>>> >>>> >>> >>> -- >>> Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ >>> >>> >>> _______________________________________________ >>> FlexRadio mailing list >>> [email protected] >>> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >>> Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >>> FlexRadio Homepage: http://www.flex-radio.com >>> >> _______________________________________________ >> FlexRadio mailing list >> [email protected] >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >> FlexRadio Homepage: http://www.flex-radio.com >> >> > > > > -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman "You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat." - Einstein _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
