Posted by
wayne burdick on
Jan 28, 2011; 4:57pm
URL: http://elecraft.85.s1.nabble.com/APF-tp5963894p5970517.html
Lyle (KK7P), our DSP engineer--a very meticulous guy--just did a very
careful re-test of the two versions of code referred to in this
thread. He found no difference between 4.17 and 4.25.
I see that Arie (PA3A) also confirmed no difference when he repeated
his own test. (Thanks for doing this, Arie.)
73,
Wayne
N6KR
On Jan 28, 2011, at 2:51 AM, Arie Kleingeld PA3A wrote:
> All,
>
> Measured the two FW's 4.17 and 4.25 with APF on S+N/N ratio at MDS
> again, and again.
> Question was: if the filter plots are exactly the same, where does the
> measured (marginal) difference of 2 dB come from?
>
> Found no difference this time. Seems that the XG2 drifted a bit in
> yesterdays measurements which, I think, caused the 2dB difference
> (despite tuning the K3 on the right freq before measurement started).
>
> Positive thing is that I could measure the improvement of S+N/N ratio
> with the APF switched on. Even with the 200Hz roofer and 50Hz DSP BW
> it
> adds a few dB. So for me it is a good tool for digging holes in the
> noise looking for weak signals.
>
> 73,
> Arie PA3A
>
>
>
>
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