Customize Osmosdr

[Gavin Jacobs]

I have GQRX 2.9 running on a Pi 3. Details are here:
https://mail.google.com/mail/u/0/?hl=en&tab=wm#sent/15fa1de8c12eb5f0?compose=1607a63e3816efa7

Then I got an upconverter and I wanted to enable the bias voltage from the rtl-sdr. I rebuilt rtl-sdr and gr-osmosdr and now using gnuradio, I can enable the bias voltage via gr_osmosdr sink block. The procedure I used is shown in the attached file.

But, in gqrx the version of gr-osmosdr used is different than the version used by gnuradio companion. In gqrx (started from a terminal) I see this:
gr-osmosdr 58b1794f (0.1.5git)

and in gnuradio companion I see this:
gr-osmosdr v0.1.4-98-gc653754d (0.1.5git)

Is it possible for gqrx to use the gr-osmosdr which I just built?

Thanks,

Jake

[Alexandru Csete]

Hi Jake,

It is possible to "overrule" libraries by using LD_PRELOAD but it I
don't see the point...

The libraries I have included in the v2.9 binary package were already
the latest version at that time + my patch for Airspy HF+ support, so
I don't see what you get from the git repositories that are not also
in my build. Have you tried to see whether it just works?

Alex

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[Gavin Jacobs]

Alex,
The librtlsdr included in gqrx v2.9 is the latest Release, but it does not include the function to turn on the bias-t. My understanding is that code was added to rtl-sdr, but has not been bundled in a release of the package.

Yes - I did try it. On GRC, if I put "rtl=0,bias=1", then using the released gr-osmosdr, it prints an error; but using my recompiled version it works. Meanwhile on gqrx, if I try to add "rtl=0,bias=1", it just doesn't work and changes the device type to Other.

It's not a big issue, because I can always power the upconverter externally. And it turns out that the bias voltage is a bit noisy, which probably comes from the Pi supply, which comes from a cheap Chinese switcher.

Thanks,
Jake