Re: Arrived! SoftRock Ver. 6 40/80 M
- --- In firstname.lastname@example.org, Milt Cram <w8nue@...> wrote:
> Tom wrote:
> > Now I need to find a place on the web that can explain the theory of
> > quadrature detection WITHOUT using mathematics :-)
> > Thanks again to Tony for this great little rig. 73,
> > Tom Curtola
> > VA3TY
> > Toronto, Ontario - Canada
> The signal at the center of your display is due to the soundcard. It
> corresponds to the xtal frequency used in your Softrock and is the
> beat" frequency of the IQ detector. If the sound card has little noisethe
> around DC and has zero DC offset, the garbage in the center of the
> spectrum will be minimal. My on-board sound card has a fairly large DC
> offset and consequently shows a fairly large signal at the center of
> spectrum. An external USB SB Live has a much lower signal at thecenter
> of the display.Tom (and Milt...),
> The neat thing about the Softrock and IQ detection is that it can
> separate signals that are below the oscillator frequency, from those
> that are above it. A standard direct conversion receiver can't do this
> because it does not have both I and Q signals-- the IQ detection can
> distinguish between positive and negative frequencies.
> Enjoy the Softrock and the many great software packages.
> 73, Milt
If it's any use, I've just uploaded an article I've just written for
our club newsletter which includes my non-technical interpretation of
the underlying magic in this mighty midget of a kit.
It's in the files section and is called Softrock.doc.
Just about to play with the second kit using a DDS60 as alternative
clock source; this Softrock kit must be the best value for 'grins per
73, Stewart Rolfe, GW0ETF