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Software Defined Radio is a computer peripheral that allows reception (and ideally also transmission) of arbitrary radio waves. Various peripherals have different frequency range, bandwidth and other capabilities. Best known are USRP (Universal Software Radio Peripherial) and RTL-SDR (extremely cheap DVB-T USB stick chipset).
On the software side, GNURadio is the most popular control software. Its modular design allows defining arbitrary signal decoding pathways visually.
We have SDR station on the table near our library (RadioLab), and some antennas on the roof. A radio-adsb.brm computer has been using RTL-SDR to generate a live map of airplane traffic (ADSB-based) over Prague. Other activities (TETRA etc.) are planned or work in progress.
Past and future:
<del>* setup [[http://www.websdr.org|WebSDR]]</del>
We are saving up for one. If you'd like to Donate with comment “RadioLab”.
TODO: Where/how to get a good antenna?
TODO: What are interesting frequencies to listen to without a super-strong antenna?
Pentium D, 1 GB, 40 GB, Ubuntu 12.04
“public” computer, you can tune in GQRX (run ~/gqrx/gqrx), experiment with gnuradio…
Remote listening - tune radio in brmlab, listen at home!
xtightvncviewer -quality 7 -encodings tight 192.168.77.35:0
Maybe you will need to start a VNC server:
root@radio-observer:~# x11vnc -display :0 -usepw -forever -auth /var/run/lightdm/root/\:0
radio@radio-observer:~$ x11vnc -display :0 -usepw -forever
ssh email@example.com "parecord --channels=1 | oggenc -q "-1" -r -C 1 -" | ogg123 -
Uncompressed (e.g. for further processing)
ssh firstname.lastname@example.org "parecord --channels=1" | aplay -r 44100 -c 1 -f S16_LE
Average delay of this chain is 1-2 seconds.
Tunnel raw data - connect remote radio to your local receiver
ssh -A -L1234:192.168.77.35:1234 email@example.com 'ssh firstname.lastname@example.org "killall rtl_tcp; rtl_tcp -a 0.0.0.0"'
Then start gqrx locally with
Works for me with 300000Hz bandwith.
P4, 1 GB, 60 GB, 10.04
currently there is a web-server with Virtual Radar map of planes running there
celeron, 512 MB, 80 GB, 10.04
celeron, 512 MB, 40 GB, 10.10
ADSB demodulator, Celeron@2.4GHz is enough (load ~0.9)
./gsm_receive_rtl.py -I dump.cfile -d 1 B0