Osmocom TETRA software

[sinager at tarapippo.net]

 OR you get a €20 (even less) RTL usb sdr dongle and save a lot of time and effort...
 
http://sdr.osmocom.org/trac/wiki/rtl-sdr8-)=
 
From: tetra-bounces at lists.osmocom.org
To: "Felix Rublack" frubi at frubi.net, tetra at lists.osmocom.org
Cc: 
Date: Mon, 17 Dec 2012 15:09:40 +0100
Subject: Re: Osmocom TETRA software


> 
Hi 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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