hi Bob,
I was considering the same thing with the Racal RA6830 since the demodulation comes through a MC1496. In AM the carrier is recovered with a mc1357 and in SSB and CW the BFO. I wanted a method where I could compare the performance of the stock system and DSP.It was interesting to see the DSP had a slight advantage under poor conditions. Also I found the dsp able to demodulate without an external phase lock to an am carrier so all the locking challanges have been eliminated. You will be stuck in SSB or CW using your method. fc
jr_dakota <[EMAIL PROTECTED]> wrote:
jr_dakota <[EMAIL PROTECTED]> wrote:
Definitely the easiest solution ... it's easy to generate a quadrature
with simple L-C networks at IF because the BFO frequency is more or
less fixed or limited in range ... it's wideband LOs that need a
digital divider quad generator
JR
--- In [email protected], Bob Stewart <[EMAIL PROTECTED]> wrote:
>
> Hi Francis,
>
> In the case of my KWM-2A, I'm just going to to use the
> BFO oscillator output and a quadrature hybrid to form
> the 90 degree signals. The circuitry will be
> amazingly simple. Take a look at KK7B's Binaural I-Q
> Receiver circuit in the handbook. The detector is in
> a schematic by itself, and I think that's all you'll
> need if you have a BFO signal in your radio. You can
> get information on making quadrature hybrids here:
> http://www.seboldt.net/k0jd/phase_notes.html I will
> also note that the DDS daughterboard (don't have link)
> is almost a perfect match, but they don't bring out
> the Q signal from the DDS chip.
>
> Bob - AE6RV
>
> --- FRANCIS CARCIA <[EMAIL PROTECTED]> wrote:
>
> > Bob,
> > I'm planning one myself for an interface to my
> > Racal RA6830 455 KHz IF. I also did the same tests
> > as you so can't wait to have the real interface. I
> > noticed the color burst crystal divided by 8 gives
> > you an IF of 8.44 KHz into the sound card. Then I
> > noticed my 3725 KHz novice 80 meter crystal would
> > also work. The Soft Rock 40 has a spare flip flop so
> > that will be the oscillator chain. I'm debating the
> > value of the double balanced Tayloe mixer. WA1GFZ
> >
>
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