Complex FIR and Stereo support for rtl_fm

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Miroslav Slugeň thunder.m at email.cz
Fri Sep 13 13:22:40 UTC 2013


Hi again,

I am working on my own SDR project for Stereo FM radio support, but i 
would like to also improve quality for rtl_fm application, i made 
unoficial patch to add:

Complex FIR - to filter strong signals close to wanted signal
Real FIR - to filter pilot from FM
Stereo FIR
Stereo Deemphasis
AGC support - it can give better resolution of IQ data

Some other improvments in FM radio code.

All FIR filters has 3 possible variants, simple, LUT, SSE2 instricts, of 
course SSE is the fastest one and it should works on Intel Atoms, but 
not on ARM.

Feel free to use any part of code in any of you programs, I know that 
this code is little to much to add it into rtl_fm, but maybe it could 
somebody help to recieve HW stereo FM radio.

Speed of SSE code is much better than anything you can get around here, 
on Core i7 it consume only 5% of one CPU, so i could demodulate at least 
80 channels at the same time in stereo quality of course.

I tried this code only on AMD64 and GCC Linux, so i am not sure if it 
can be compiled under windows.

-- 
Miroslav Slugeň
+420 724 825 885

Teramos Multimedia s.r.o.

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