[Elecraft] APF measurements: FW 4.17 better results by 2 dB

[Arie Kleingeld PA3A]

All,
where I mentioned Dual PB, I mean ofcourse the APF, because that the 
discussion here.

Sorry If that is not clear.
73
Arie PA3A

Op 27-1-2011 12:44, Arie Kleingeld PA3A schreef:
> Hello all,
>
> Did some measurements on the different frimware versions. This time not
> a BW-plot but  I measured S+N/N ratio's.
>
>
> I have no lab equipment but I have a K3 with dBV measurements, XG2 and
> the stepped attenuator from elecraft.
> I measured the difference of the K3 dBV-reading in signal off (=N) and
> signal on (=S+N)
> AGC off, mode CW, 400Hz BW and 400Hz Roofing.
> RX gain of the K3 has been calibrated with XG2 and the K3 utility.
>
>
> This is what I found.
>
> _FW 4.25 and 4.21 (both give the same measurement values):_
> At MDS level (stepped att on 20dB to reach this level)
> normal 400 Hz BW: S+N/N  = 3dB  (as expected, hi)
> 400 Hz BW + dual PB: S+N/N = 10 dB
>
> Now signal level 6dB under MDS (26dB att instead of 20dB):
> normal 400 Hz BW: S+N/N  =   0.5 dB
> 400 Hz BW + dual PB: S+N/N = 4 dB
>
>
> _FW 4.17_
> At MDS level (stepped att on 20dB)
> normal 400 Hz BW: S+N/N  = 3dB  (as expected)
> 400 Hz BW + dual PB: S+N/N = 12 dB (THIS is 2 dB BETTER)
>
> Now signal level 6dB under MDS:
> normal 400 Hz BW: S+N/N  =   0.5 dB
> 400 Hz BW + dual PB: S+N/N = 6 dB (THIS is 2dB BETTER)
>
>
> There are probably people that can measure this far more better than I
> did with better equipment.
> But this is what I can come up with here.
>
> 73,
> Arie PA3A
>
>
>
> Op 27-1-2011 0:52, Barry N1EU schreef:
>> Forget it - full stop!
>>
>> I just ran a spectral analysis of the current firmware versus the very first
>> APF implementation (mcu 4.17 dsp 2.65) from 11/3/10 AND THE PLOTS ARE
>> ABSOLUTELY CONGRUOUS!  The APF implementation hasn't changed a bit (or a
>> byte).
>>
>> Have a look:  http://n1eu.com/k3apf.gif
>>
>> magenta and green plots are taken with width = 200hz
>> aqua and yellow plots are taken with width = 100hz
>>
>> Barry N1EU
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