Configuration for KX3 I/Q via USB soundcard

[Matthew Bohnsack]

Hello,

I have an Elecraft KX3, and I would like to connect its I/Q output via a USB soundcard to gqrx, for use as a panadapter.  However, I'm stuck trying to figure out what to specify in gqrx's I/Q input dialog.  

I'm using Fedora 22 and a SD-AUD20101 USB sound card that has a 96 kHz sample rate.  The sound card is said to have stereo input despite the description saying mono input only.  Here are some links to the device:

http://www.amazon.com/gp/product/B006SF68P2?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00

http://www.sybausa.com/productInfo.php?iid=1191

When I start gqrx, I'm prompted to enter a device string for I/Q input, and I'm struggling with what to specify to signify my USB sound card.  Can someone provide some pointers?  How can I specify my USB sound card as input to gqrx?  How can I ensure the widest possible panadapter bandwidth with this setup?

Thanks!

-Matthew

[Darren Long]

Hi Matthew,

I'm pretty sure this can't be done. Here are some things that do work
with the KX3 though ...

1) gr-kx3

https://github.com/g0hww/gr-kx3

This uses gnuradio and works OK with the version from the gqrx repos

2) qtrfiq

https://github.com/g0hww/qtrfiq

This uses gnuradio and works OK with the version from the gqrx repos,
but needs gr-fosphor.

Please ignore the stuff in the readme about editing the generated
python, it works ok now, but I haven't updated the readme yet.

3) QtRadio with dspserver (from ghpsdr3-alex) and ghpsdr3-kx3-server

https://github.com/g0hww/ghpsdr3-kx3-server
https://github.com/alexlee188/ghpsdr3-alex

This uses the HPSDR codebase rather than gnuradio and will take some
building and configuring. With this you get a full SDR receiver
capability though, so it is pretty nice to have. See a pic here:
http://www.g0hww.net/2014/12/ghpsdr3-kx3-server-available-on-github.html

Hope this lot is of some use/interest.

Cheers,

Darren, G0HWW

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[Alexandru Csete]

Hi Matthew,

Darren is correct that gqrx does not yet support generic audio
devices. Furthermore, I would like to point out that the device you
linked to only has mono input, so it will not work as an I/Q source.
You need a device that has stereo input and probably line level and
not microphone.

Alex

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[Matthew Bohnsack]

Thank you Darren.  I'll try out those references.

-Matthew, K5ATN

[Matthew Bohnsack]

Alexandru,

Thanks for confirming that gqrx doesn't yet support generic audio devices. 

I understand that a stereo input is required for both I and Q signals.  Despite my device's spec sheet saying mono input only, there are a number of reports saying it does stereo and that it works for this sort of application.  For example, it's listed (and recommended) here: http://www.telepostinc.com/soundcards.html

I will rig up something to personally confirm that it can receive in stereo, before proceeding.

-Matthew, K5ATN