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Re: [Discuss-gnuradio] QT Vector sink question?


From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] QT Vector sink question?
Date: Fri, 08 Jun 2018 11:12:23 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0

On 06/08/2018 11:04 AM, Glen I Langston wrote:
Hello Gnuradio Aficionados,

In case any has had similar problems with the AIRSPY and spectra aliases,
the problem is solved very simply.   Do not heave the IQ balance setting at 
“Automatic”
as this causes IQ balancing on Linux devices.  This was the cause of our 
problems
with aliases in the spectra.  The code seems to be OK on Macs but definitely 
causes
problems on Linux.

Who should I talk to about this and other OSMOSDR issues with Airspy code for 
Linux?

Thanks

Glen

PS there was an OSMOSDR Gnuradio companion interface change and I’m confused
over what, exactly, the settings for “linearity” and “sensitivity” do for 
AIRSPY.
The I/Q balancing code in gr-osmosdr doesn't work very well with radio astronomy--it will essentially never converge. It's only really useful for spectra that contain a number of narrow-band features, which, hopefully, radio astronomy doesn't have :)

Automated I/Q balancing is a subject where there are NO universal "passive" solutions. Each approach has its place. Radio Astronomy isn't one of
  them :(



On May 21, 2018, at 2:50 PM, Glen I Langston <address@hidden> wrote:

Hello all,

Thanks for all the interesting discussion.  Very educational.

I’ve got a pair of questions concerning the QT vector sink.

My application uses the vector sink for plotting and diagnostics
of averaged spectra.

I’m getting the impression that the QT vector sink is using a good fraction
of my computer resources, despite trying to reduce the update intervals.

My question is 1) can I somehow turn off the Min and Max functions and any
averaging of the data in the QT vector plotter?

The second question concerns a waterfall plot for the vectors I’m
generating.   The QT waterfall plot does not accept a vector.
If I turn the vector back into a stream, then the QT waterfall plot then
Fourier transforms the spectra back. making a mess.

So the Second question: 2) is there a way to provide the QT water fall plotter
with a Vector and not have it FFT the data?

Thanks

Glen

FYI The code for Radio Astronomy is currently available
(both observing interface and examples) at:

git clone http://www.github.com/glangsto/gr-nsf





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