[Elecraft] SDR-IF and I/Q questions

[k.igor at comcast.net]

Richard, 

SDR is essentially a direct conversion radio, so it is much simpler than conventional heterodyne radio. If you want to use SDR_IF you will need something like additional SDR, like S oftRock  to convert K3 IF signal to I/Q signals. I have this setup and it works fine, without any images. The fact that you have images usually indication that one of the signals (I or Q) is not reaching your sound card. Y our sound card shall have stereo input with good separation of the channels for this to work. Most built in laptop sound cards will not work because they have mono input. 

For "on par" performance you need one of the expensive sound cards with conversion rate of 200 kHz or near of . E-MU brand comes to mind but there are others. 

Like SDR, P3 also converts the IF signal to I/Q, but does it digitally, so these signals are not available to outside world.  P3, at least in it's current design, cannot accept externally generated I/Q signals either. Since the KX3 by nature is SDR, the output of it is the IQ signals and so P3 cannot be used with it.        


73, 

Igor, N1YX 


----- Original Message -----


From: "Richard Fjeld" <rpfjeld at embarqmail.com> 
To: "elecraft posting" <elecraft at mailman.qth.net> 
Sent: Monday, November 14, 2011 1:49:59 AM 
Subject: [Elecraft]  SDR-IF and I/Q questions 

I didn't get any responses to my questions asking for info about those who were successfully running  SDR-IF software on a par with a P3, or from those who were not successful. 

I did not find any ground loops in my system, and I still do not know why some SDR-IF programs run with mirrored images and a few do not.  IMHO, those that do not have mirrored images with my computer, are not on par with a P3. 

So, I am moving on to other things. I have decided that, at my age, life is too short for SDR. 

I am greatly disappointed to learn that the KX3 will not accept a P3. 

Richard Fjeld, n0ce 
rpfjeld at embarqmail.com 
I'd rather be learning. 


  
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