Pete,
The Spur Reduction algorithm is a passive algorithm that is very simple.
It simply keeps the DDS away from the worst known spur frequencies. So
instead of doing tuning at 1Hz increments, we do tuning at 3.051kHz on
the DDS and do tuning below that in software.
Given all of that, the fact is that the spur that we are "moving" is
really just being adjusted up to 3.051kHz in software according to the
algorithm. The spur reduction is not "active" in the sense that it
sense spurs in DSP and does anything intelligent as a result. This is
something that I expect to eventually end up in our software at some
point.
Eric Wachsmann
FlexRadio Systems
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> radio.biz] On Behalf Of N3EVL
> Sent: Saturday, April 29, 2006 9:23 AM
> To: FlexRadio@flex-radio.biz
> Subject: [Flexradio] Spur Reduction Observation...
>
> I noticed while listening on 40m on 7.209MHz that there is a spur
> (actually
> what appears to be a spur reduction artifact, since spur reduction is
ON)
> at
> 7.208Mhz. This is, of course, withing the passband for LSB.
>
> With spur reduction turned off, the spur relocates to 7.2606.
>
> I'm wondering if it is normal behavior for the spur reduction
algorithm to
> apparently correctly identify a spur and relocate it withing the
desired
> passband. Notice that if I was listening on USB, the relocated spur
would
> not be a problem since it would be well outside the chosen passband.
>
> Assuming that USB vs LSB is even a factor, is it possible that the
spur
> reduction algorithm is assuming the desired passband is USB, even on
bands
> such as 40m where the convention is LSB?
>
> Pete, N3EVL
>
> Sdr-100, 100w, ATU, Dell P4 2.8MHz 512MB, Win XPpro/SP2
>
>
>
>
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