[Elecraft] KX3 SDR

[Enzo Adrian-Reyes]

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.

I am trying to design a digital mode, and while I do understand the
concepts, could do it in GNU radio but it abstracts a lot of this away, and
I would like to do this in C/C++
So before getting there I have to know what is going on, especially what
data is coming from the device.

Thinking about it yeah it would have to be a stream of IQ signals coming
from the KX3 with a certain freq set, but I am guessing its in the time
domain. Not at the freq domain?



On Thu, Jul 28, 2016 at 10:26 AM, Don Wilhelm <donwilh at embarqmail.com>
wrote:

> If you are writing your own software, you will have to become proficient
> in Digital Signal Processing.  The I and Q signals are simply baseband
> signals that are 90 degrees out of phase - by themselves, they will do
> nothing but audio signals, but with DSP processing, they can do most
> anything that is possible in the math of digital signals - limited only by
> your processing power and skills at DSP signal processing.
>
> Run them through FFT transforms to convert them to digital signals, and
> then do the math of your DSP algorithms to produce whatever you want -
> panadapter display, demodulation, etc.  You can add filtering and other
> things like AGC, Noise Reduction, Noise Blanking, and a whole variety of
> effects.  It is all in how you choose to implement you DSP mathematical
> functions.
>
> Rather than write your own, there are several DSP applications available
> for free or at nominal cost - try HDSDR or NaP3 or WIN4K3 as examples.
> Once you see what is happening with those applications, you may be moved
> to write your own DSP application to process the I and Q signals.
>
> 73,
> Don W3FPR
>
>
> On 7/27/2016 7:16 PM, Enzo Adrian-Reyes wrote:
>
>> Hi All
>>
>> Yes this topic might be a little bit more complicated than the title
>> suggest.
>>
>> So I have the KX3 plugged into the audio input of my computer, and its
>> sending quadrature data (IQ) to the sound card, the sound card samples at
>> 96Khz.
>>
>> So my question is how I process this? Yes I know use a piece of software,
>> but I am trying to write this, I know the IQ data is coming through down
>> and if I use the right process on the IQ data I get base band data out. I
>> kind of know that however I dont understand the SDR data coming out, so
>> for
>> example and I getting sample of IQ data at freq point Y, or is it  a
>> circular buffer arrangement.
>>
>> I guess what I am saying is, is the IQ data coming from teh KX3 data from
>> teh Centre Freq (+/-) the bandwith scope, or just the centre freq + some
>> additional side bands?
>>
>> How are bandwith and sampling rate related? I mean if I am sampling at at
>> 96Khz, with a band with of 48Khz does that mean I am only getting 2
>> samples
>> per second at perticular freq??? Or am I getting the entire band of 48Khz
>> at 96Khz.
>>
>>
>>
>