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Ari Kaspari ari.kaspari at googlemail.comHi thank you for your comment.
What do you think about the following thought:
I take two old radioscanners each has 12.5 kHz channel pattern
("Kanalraster") , Tetra uses 25 kHz.
Then I make for each scanner a FM modulation in Software or on FPGA and
after a signal addition. Now i should have the modulated Pi/4-DQPSK signal
back. Or haven’t I?
2012/12/17 Felix Rublack <frubi at frubi.net>
> Hi Ari,
>
> On 17.12.2012 10:37, Ari Kaspari wrote:
> > In your Picture
> >
> http://tetra.osmocom.org/trac/graphviz/caf863214dab2ac9e1beead8b122318020ecb403.dot.png
> > it seems to me, that I only need PCM Samples from my radioscanner.
> > Thus I think i can stream the discriminator output via soundcard
> > (PCM-Samples) into a linux pipe and use this pipe for your omso-tetra
> tool.
> >
> > Is this possible?
> > Or is my radioscanner not possible to "stream" the correct channel
> pattern?
>
> No, i don't think so. Your radio scanner does FM demodulation. But the
> TETRA signal is modulated with Pi/4-DQPSK (or QAM - not supported by
> osmocom-tetra). So the real information is already lost, when it comes
> out of the discriminator output.
>
> The FUNcube Dongle (linked schematics) does no demodulation. It just
> digitise the I/Q-Data and puts it in the left/right channel of the PCM
> stream.
>
> Greetings
> Felix
>
>
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