Re: [Discuss-gnuradio] Multi-rtl - making multi-channel receiver out of multiple RTL-SDR dongles

Hi Juha,

It wouldn't be as simple as it was for me as a developer and as it
(hopefully) is for the end user without your hardware mod.

Can you say something more about the residual center frequency
difference? Where might it come from? I prepared little test of
coherency between the receivers (multi-rtl/examples/test_multirtl.m).
Among all the figures that it shows there is a plot of relative phase
offset of signals coming from the receivers. In fact I have seen linear
phase change on that plot - that corresponds to some central frequency
offset. If I know what is the source of this offset maybe I will be able
to find some way to fix it in software.

--
Piotr

W dniu 25.05.2016 o 08:24, Juha Vierinen pisze:
> This is awesome! I'll definitely try this out soon. I use one off
> python scripts to find the sample offset and the small residual center
> frequency difference. This simplifies the process significantly.
>
> This should make it much easier to implement a passive radar block, or
> an interferometry block.
>
> juha
>
> On Tue, May 24, 2016 at 4:03 PM, Piotr Krysik <perper@o2.pl
> <mailto:perper@o2.pl>> wrote:
>
> Hi all,
>
> I want to announce new GNU Radio related project prepared by me -
> Multi-rtl:
> https://github.com/ptrkrysik/multi-rtl
>
> It is a Gnu Radio block that combines multiple RTL-SDR receivers into
> one multi-channel receiver.
>
> Only hardware modification to RTL-SDR dongles required is connecting
> them to a common clock source (i.e. one of the dongles' oscillator as
> Juha Verinen showed once). Each channel can work on a different
> central
> frequency.
>
> Everyone who wants to know how it was achieved is invited to read my
> github page:
>
> https://ptrkrysik.github.io
>
> Best Regards,
> Piotr Krysik
>
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