Tim, This sounds like interference coming from the 12 V to +/-15 V DC to DC converter (NMA1215S) on the PIO board. I have added some extra filtering, but still sometimes can see and hear it wandering across the panadapter window at a level -155 dBm. Naturally, that low level can be seen only without antenna connected to the SDR-1000. In the normal listening it disappears under the noise coming from the antenna.
73, Ahti OH2RZ On 12/05/06, Tim Ellison <[EMAIL PROTECTED]> wrote: > I observed an interesting phenomenon this evening and I wonder if my > assumption is on track. > > When I started up my SDR1K this evening, I had it connected to a dummy > load to do a little audio testing. On the Panadapter, I noticed a > signal 500 Hz wide that was about -100dBm in intensity that sounded like > a whistle. I could really hear it because the noise floor was about > -138dBm. The signal never changed in intensity, but was rapidly > increasing in frequency. I checked on another radio and the signal was > definitely in the SDR1K. > > I started tracking it at around 14.190 KHz and followed it up the band. > As it "crawled" up the band, the rate of frequency change decreased, but > the intensity never did. > > I tracked it to all the way to 14.290 KHz where it finally stabilized > its frequency change. > > This whole process took about 20 minutes to complete. > > At this point I started transmitting and the peak jumped to 14.335 KHz. > Once I quit transmitting it started to drop again to stabilize around > 14.328 KHz. So it looks like this phenomenon is very likely > temperature dependent. > > Am I correct to assume that this phenomenon is related to DDS thermally > instability?? If it is DDS related, shouldn't the intensity of this > signal decreased in intensity as it stabilized or should this S5 signal > always be here? Should this DDS noise be this strong in intensity? > > I am just trying to figure out if this is normal operation of do I have > some other problem. > > Any comments and opinions are welcome. > > -Tim > --- > Tim Ellison <mailto:[EMAIL PROTECTED]> > Integrated Technical Services <http://www.itsco.com/> > Apex, NC USA > 919.674.0044 Ext. 25 / 919.674.0045 (FAX) > 919.215.6375 - cell > >>> PGP public key available at all public KeyServers <<< > Skype: kg4rzy > > > > > _______________________________________________ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ > FlexRadio Homepage: http://www.flex-radio.com > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
