The signals at the IQ jack on the KX3 are analog, not digital. They are
centered approximately 8 kHz away from the dial frequency as the KX3
uses an internal offset of 8 kHz. Depending on the firmware release and
user settable options, that offset may be on either side of the center
of the IQ audio.
The rate at which you sample it in general will determine, and in any
case will certainly limit, the maximum bandwidth you can digitize for
further processing.
Internally, the KX3 samples the analog IQ signals at 48 kHz.
Externally you can sample at any rate you desire that your A/D
(soundcard) will support, as long as you take into account anti-aliasing
filtering and the bandwidth/response of the analog circuitry in the KX3
itself, and any similar limitations of the soundcard including its
analog circuitry and the characteristics of its ADC. For example,many
ADCs do noise shaping of their sampling systems to prefer 0 to 20 kHz at
the expense of internal noise humps above 20 kHz.
General information about the frequency rolloff of the KX3 analog IQ
signals have been discussed here in the past, and I think (but have not
checked) that they are in the Owner's Manual. You can also observe
them, perhaps using your proposed soundcard and the tools that gnu radio
provides for you to explore these topics.
73,
Lyle KK7P
On 7/27/16 5:43 PM, Enzo Adrian-Reyes wrote:
Hi
Yes, well I have used those in the past, hence my confusion, when I see
bandwith of a SDR at lets say 24Khz
and I am sampling at 48Khz. Does that mean I am sampling the whole bandwith
of 24Khz centered on freq X, or
am I a sampling some point Y at +/- from the center frequency...
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