i'm just guessing here, but could all these spurs and fences and such be caused by power supply noise from the external switching or ripple from linear power supplies?
if the PSSR of the linear stuff is low enough or the noise high enough, it falls within the signal dynamic range and power supply noise becomes signal. a lot of switchers develop a real nice wideband sinX/X noise power distribution above the fundamental. if the noise or ripple is within the passband of the dsp stuff it can be hard to filter out. in my experience of running analog into high speed analog processing hardware is generally met with disaster after the A to D converters unless i have extremely clean supplies from DC to well past the PS switching and signal frequencies on the analog side. switching power supplies tend to send noise straight through the whole circuit. just my 2 cents! phil AB2JL ----- Original Message ----- From: "Cecil Bayona" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Tuesday, August 15, 2006 9:56 AM Subject: Re: [Flexradio] Spurs and Picket Fences > In my case, turning spur reduction seems to make it worse, the spurs > are -50dB > or even higher, it's totally useless on 10 meters. > > On Tuesday 15 August 2006 06:59, Jimmy Jones wrote: >> Did you guys have Spur Reduction checked? >> >> I went across the entire 10 meter band just now and had only 1 spot with >> a >> spur. >> I was in upper sideband running a bandwidth of 4 khz and the spur was in >> my >> passband at 28.583 ,584 and 585. >> The Signal level was -87.3 dBm. Nothing in the entire band other than >> this >> spur was above -120 dBm. >> >> >> >> _______________________________________________ >> 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 > > -- > > Cecil > KD5NWA > www.qrpradio.com www.hpsdr.com > > > "Sacred Cows make the best Hamburger!" Don Seglio Batuna > > _______________________________________________ > 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
