Posted by
Joe Subich, W4TV-4 on
Aug 12, 2010; 7:23pm
URL: http://elecraft.85.s1.nabble.com/P3-a-modest-proposal-for-QSY-tp5410950p5417531.html
> What Joe W4TV is saying is that a P3 is "never more than 50
> cycles" from the K3 frequency readout when correctly
> calibrated. With a 100 cycle bandwidth, this is somewhat
> acceptable.
You take what I said out of context. That statement was in
reference to the FREQUENCY DISPLAY. The FREQUENCY DISPLAY is
never move than 50 cycles from the K3 FREQUENCY DISPLAY. That
divergence is ONLY because the K3 FREQUENCY display ROUNDS to
the nearest 100 Hz (0.1 KHz).
> However, on a Flex, I can click on a signal and be DEAD ON
> the signal I have selected.
If you have sufficient span (visual resolution) selecting a
signal on the P3 will put you dead on in the K3. However,
it is just like clicking on the spectrum or waterfall in
any digital program, the mouse has a one pixel resolution -
if you are trying to use a spectrum/waterfall span of 100 KHz
in a window that is 360 pixels wide (1/4 of an SXGA screen),
the BEST you can do is +/- 138 Hz (100 KHz/360).
If you are using PowerSDR (the real FlexRadio) in full screen
mode on a 1600 pixel wide screen, each pixel will represent
about 70 Hz (100KHz/~1400 - the spectrum/waterfall is not full
width) and you can get within +/-35 Hz.
The same factors apply to the P3 ... your maximum accuracy is
SPAN/DISPLAY RESOLUTION. In the case of a 100 KHz span,
100KHz/480 +/- 100Hz ... that's one pixel and represents the
resolution limit of the display. However, I don't see it as
a real issue since a 100 KHz wide view only makes sense on a
relatively quiet band and you're not going to be using a 50 Hz
wide filter under those circumstances.
73,
... Joe, W4TV
On 8/12/2010 2:11 PM, Lu Romero wrote:
> So now I am getting a much better understanding...
>
> What Joe W4TV is saying is that a P3 is "never more than 50
> cycles" from the K3 frequency readout when correctly
> calibrated. With a 100 cycle bandwidth, this is somewhat
> acceptable.
>
> However, on a Flex, I can click on a signal and be DEAD ON
> the signal I have selected.
>
> I have never operated a LP-Pan, but can I assume that it
> will function just like the Flex (it is the same software
> front end after all)?
>
> And Skimmer's waterfall display is also just as accurate.
>
> This means that if I am a "shoot fish in a barrel" mult
> operator and are combing the band for signals, I would be
> much more efficient time wise using a Flex/LP-Pan or a
> Skimmer than using a P3 on my K3, even with the Macro Magic
> CWT solution, right? The upside is that no computer is
> needed (which is a non trivial thing, IMO).
>
> Will/can the P3/K3 combination approach the accuracy of the
> above systems?
>
> -lu-w4lt-
>
>
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