[Elecraft] KX3 I/Q output and band width

[Walter Underwood]

You actually have 22 kHz of in-phase signal and 22 kHz of quadrature signal
on the stereo output. You can combine those to get 44 kHz of bandwidth.

More info here:

https://en.wikipedia.org/wiki/In-phase_and_quadrature_components

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Feb 4, 2020, at 2:45 PM, gt-i at gmx.net wrote:
> 
> Hello,
> for a long time I just haven't looked into the details, but now I did
> and I'am confused.
> When I plug it into a soundcard it appears to show the current station
> in the center of the display, to my understanding the center of the
> display is the half of the sampling frequency of the sound card.
> This ist at least confirmed in the manual pg. 26 (Rev C5).
> 
> When I sample the I/Q signal by myself, the same signal appears at the
> lower end of my spectrum.
> Now it looks like I'm not getting the full bandwidth sampled? With fs of
> 44.1kHz I can only see 22kHz of bandwidth after FFT.
> 
> So, according to many articles I read about FFT, the resulting bandwidth
> is always fs/2. So how can we see 44kHz of spectrum on a 44kHz sound
> card? I'm confused...
> 
> 73 Gernot DF5RF
> 
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