KX3 I/Q output and band width

[gt-i]

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

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[gt-i]

Walter,
thanks for the pointer. Will give it a try. Not sure how to combine the
two, lets see.
73 Gernot

Am 04.02.2020 um 23:52 schrieb 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, [hidden email] 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
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]