Re: Osmocom TETRA software

 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(a)lists.osmocom.org To: "Felix Rublack" frubi(a)frubi.net, tetra(a)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(a)frubi.net>Hi Ari, On 17.12.2012 10:37, Ari Kaspari wrote:> In your Picture> http://tetra.osmocom.org/trac/graphviz/caf863214dab2ac9e1beead8b122318020ec…> 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 theTETRA signal is modulated with Pi/4-DQPSK (or QAM - not supported byosmocom-tetra). So the real information is already lost, when it comesout of the discriminator output. The FUNcube Dongle (linked schematics) does no demodulation. It justdigitise the I/Q-Data and puts it in the left/right channel of the PCMstream. Greetings