[Discuss-gnuradio] RDS decoding

[jmfriedt]

As briefly mentioned at FOSDEM, I have been investigating RDS since last 
christmas, trying to
tackle each issue step by step from LO synchronization for BPSK demodulation, 
bit decoding,
sentence synchronization, station name and free text extraction, error 
correcting code implementation
and finally transferred time analysis. My objective was of course not to 
compete with gr_rds, used
as a reference, but to acquire a detailed understanding of each step. Since I 
protoype with GNU/Octave,
I wanted to convert most digital signal processing from LFSR to linear algebra 
(matrix). I think I 
pretty much understand now the whole process, despite designing the error 
correcting code being still 
beyond my capability. An internal lab presentation on the topic is now 
available at 
http://jmfriedt.free.fr/slides_rds.pdf
and for the French speaking audience, accompanying article (in French at the 
moment, will be translated 
ASAP to English, as soon as I have completed RDS v.s GPS time comparisons) at 
http://jmfriedt.free.fr/lm_rds.pdf

I am well aware of Tom Rondeau's sponsoring Polyphase clock recovery, but at 
the moment I could
only figure out how to use MM-Clock recovery and MPSK, which worked quite well 
for my purpose.

Any feedback welcome,
JM

-- 
JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 26 rue de l'Epitaphe, 25000 
Besancon, France