rtl-sdr, SDRSharp under Ubuntu/mono, high CPU load - compared with GQRX

Alexandru Csete oz9aec at gmail.com
Sun Mar 10 19:59:12 UTC 2013

On Sun, Mar 10, 2013 at 8:01 PM, Lorenz Wiedemann <lorenz at schlagseite.de> wrote:
> Hello,
> I am running an RTL2832 USB stick (R820T tuner in it) and SDRSharp via
> Mono under Ubuntu 12.04 with a Pentium-M 1.5GHz and 1,5 GB RAM.
> SDRSharp
> With sample rates of 0.25M and 1.024M, I'm "suffering" from 100% CPU
> load and temperatures around 70°C - this can't be healthy for the
> laptop... Switching the waterfall off and speed etc. to minimum doesn't
> help very much. RDS is displayed fine, all functions seem to be OK. RAM
> space is not filled up (30%).
> Any advice for a "smoother" running on such an "old" machine...?
> http://superkuh.com/rtlsdr.html#sdrsharpappnote said "it can even run on
> my old 1.8Ghz P4 laptop".
> GQRX did run using the QtPro way as described in the wiki, but after
> recent update of GQRX the DC spike at centre frequency appeared (it
> wasn't there before), and massive stuttering of audio and the "OOOOOO"s
> in terminal window at a lot of different sample rates made the usage of
> GQRX worse. (right, this should be posted in a GQRX forum...)
> Anyway, did someone notice that GQRX update (ca. first days of march
> 2013) lead to problems ?

I have added a new DC removal algorithm in February and it is disabled
by default. You can enable it in the receiver under input controls.

There have been changes to the way how devices are labeled and
identified, so it may be a good idea to clear your configuration:
rm ~/.config/gqrx/default.conf

If there are still problems I hope you can help me find out which
commit introduced problems.


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