Since the DDS is only used as a clock source the spurious stuff I see may be due to some other mixing events within the "system". I have powered the DDS and the SoftRock V5 from separate gel cells so the power source is not an issue. I have not seen any improvement with clamp-on ferrites on the power, antenna, and the 12 inches of RG-174 feeding the DDS to the V5. Most of the spurious stuff is 10db, or less, above my noise level. Thus stronger signals come through quite well and I can enjoy the good fidelity of the DC receiver when listening to some of the shortwave broadcasts. For Ham use the presence of low level spurs makes tuning across a band looking for a weak signal very difficult.
>From all of the comments I have seen on DDS's as VFO's the 10bit DAC is probably producing the best I can expect. With the need for a tracking/adaptive wide-band phase/amplitude suppression system the xtal based IF application, or a 96khz band slice, may be best. Now, I did have an SDR-1000 and I admit that I never did any real tests Ham band edge to edge on image rejection. So, how does the SDR-1000 fare in maintaining Ham band image rejection balance with only 1 phase/amplitude setting???? Dick N3HKN --- In [email protected], "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > > Dick N3HKN: > > There is that question about the square wave verses the sine wave. The idea of using the DDS sort of board for the lower i.f. in a receiver makes sense in light of the spurious reponce you mentioned. In a narrower i.f. portion of the chain where the extended band is cut off some. > > Someone was telling me that the Soft Rock 40 circuit however may prove to be ideal in the long run, I am wondering how a sine wave will operate in broadbanded terms to 96 Khz? I seem to think the later would be more ideal in getting rid of spurs. I guess there is no ideal circuit from all of the discussion going on so far. > > Time will tell more as more ideas are built and tested. > > Dan > > > _____________________________________________________________________ > Call Anyone, Anytime, Anywhere in the World - FREE! > Free Internet calling from NetZero Voice > Visit http://www.netzerovoice.com today! > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
