[hpsdr] Fwd: Horton LO - further thoughts

[Robert McGwier]

There are two events here.  Change the DDS or Covington_Harman VCO and 
the second is the software NCO.  The eventS (large S emphasizing plural) 
will be run asynchronously.  There will be no way to guarantee that 
these events will be isochronous, much less simultaneous.  This will 
introduce large phase distortions as the tuning pop propagates through 
the filters.  I think this is hard.

Bob
N4HY




Jim Miller wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> While we're waiting for adaptive cancellation of big sigs mentioned by Bob 
> in the HPSDR presentation it might make sense to make a "tweet reducer" 
> knob.
>
> This would be a knob that when turned would move the DDS output frequency 
> while moving the software decoder to offset the movement thus keeping the 
> same tuned frequency.
>
> The operator upon hearing a interfering signal or signals could turn the 
> "tweet reducer" until a quiet spot was realized as a result of moving a spur 
> off a mixing signal.
>
> There's no guarantee one could be found on a jammed band but I suspect at 
> least in this part of the sunspot cycle it would be worth implementation 
> most of the time.
>
> And that would give us two more Analog Devices product cycles to reach new 
> lows in the SFDR of their products! ;-)
>
> This could be in combination with the already existing approach of selecting 
> "tuned frequencies" which have minimum spurious output.
>
> That's one thing I really like about the way this project is going. You can 
> plug in the "next great thing" when it's ready yet enjoy what you've got 
> now.
>
> 73
>
> jim ab3cv 
>
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AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
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