RFSpace SDR-IQ Question on Gain settings GNU Radio osmocom Source

Greg gs-raven at comcast.net
Fri Dec 21 23:19:30 UTC 2018


Hello, I hope this is the correct list to ask this question.

I have an SDR-IQ connected via USB to Ubuntu 18.04 and version 3.7.13.4
GNU Radio.  I am getting data from the source at correct center
frequency and sampling rate, however ...

I am having trouble find 3 of 4 gain controls.
I believe these to be the settings affecting the device gain:

1. RF Gain:  -20, -10, 0, 10 dB.  These I can successfully change via
the RF Gain setting in the Osmocom source.  It's good!

2. IF Gain: 24, 18, 12, 6, and 0 dB.  This is a "digital gain" and
changes a coefficient of the "6620 Digital Downconverter", which
apparently is hardware in the SDR-IQ which does filtering and
decimation.

3. Preamp Gain, via a "GN Code" of range 0-127, which goes from Off,
and then a range of -8.08 to 34 dB.

4. A step attenuator with 0 and 10 dB settings.

I got the above by examining the "SpectraVue" Windows application for
the SDR-IQ provided by RFSpace.

#1 is no problem, it works.  What about 2, 3, and 4?
So is there any hope of controlling these settings with the osmocom
source?

Regards,
Greg R





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