Very, very useful, thanks for sharing Martin. Cheers Richard
On 17 March 2010 14:40, Martin DvH <gnuradiom...@olifantasia.com> wrote: > Hi all, > > I wrote two gnuradio AFC (Automatic Frequency Control) demos > > This AFC technique can come in handy when your tuning is critical and > there is a frequency offset or doppler shift to be expected. > (Like when trying to receive NOAA weather satelites which can have a > substancial doppler shift. I am also working on an updated gr-noaa > receive script which uses this AFC. ) > > There is a broadcast FM demo and a NOAA weathersatellite narrowband FM > simulation demo. > > You can discuss and give feedback on the gnuradio AFC demo's here: > http://www.gnuradio.eu/cms/nl/node/203 > (But feedback on the gnuradio mailinglist is also OK of course) > > You can read about and download the gnuradio AFC demo's here: > http://www.olifantasia.com/projects/gnuradio/mdvh/AFC > > Here follows the README: > > Gnuradio AFC demo's > > This directory contains gnuradio GRC and python example scripts for > using AFC in an FM receiver. > > There is not (yet) a AFC gnuradio block. > So these examples implement the AFC by lowpass filtering the FM > demodulator output and putting the result in a variable sink. > The variable sink then sets the center frequency of the frequency > translating channel filter. > This compensates any frequency offset or doppler drift. > > To limit the performance penalty of calling python code from the > samplestream, the code is only called once a second. > > The critical settings of this feedback loop are: > AFC_gain (float) > AFC_IIR_alpha (float) > AFC_update_rate (float value: seconds between updates) > > If you want to use this for a different FM signal type also make sure > you set the right channel_bandwidth and max_dev (=Maximum FM frequency > deviation in Hertz) > > Have fun > > 17 Mar 2010 > Martin Dudok van Heel > > Olifantasia > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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