Posted by
Lu Romero - W4LT on
Aug 13, 2010; 12:54am
URL: http://elecraft.85.s1.nabble.com/P3-a-modest-proposal-for-QSY-tp5410950p5418434.html
No worries. I figured this stuff out in a later post. The
K3 is the boss, the P3 is the slave. Sorry about the
bandwidth. I aint thinking correctly at work. Trying to do
too much at once.
-lu-
----- Original Message Follows -----
From: "Joe Subich, W4TV" <
[hidden email]>
To:
[hidden email], Lu Romero <
[hidden email]>
Subject: Re: [Elecraft] P3: a modest proposal for QSY
Date: Thu, 12 Aug 2010 15:23:09 -0400
> > 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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