On 07/16/2014 03:08 PM, Marcus Müller wrote: > this doesn't look like FSK, because then the amplitude of the > oscillations shouldn't change (only their frequency). > If I had to guess, it would be on-off-keying, and you could simply > detect that by squaring the signal, and using the integrate block on > that, with a integration length amounting to your symbol duration in > samples, which might be a little hard to guess from the signal you > posted, but maybe you know the symbol rate from elsewhere, or can > determine it by comparing signals from different battery states?
The dips might also be between bursts -- it does look a bit like FSK, but hard to say. Stefan: If you mix this down to zero, your signal will be complex anyway (radio signals are also always real, but we don't care :D ). Then you can put it into a quadrature_demod_cf. Question is, how do you synchronise? Maybe you can use those dips to do that... Or maybe the symbol timing is well defined, then it's easier. M > > Greetings, > Marcus > > On 16.07.2014 14:51, Stefan Oltmanns wrote: >> Hello, > >> I would like to write an application that checks the battery status >> of wireless microphones. The battery status is transmitted as a >> very low frequency (below 10 Hz) signal that is mixed in the normal >> audio. I was able to filter the signal out of the demodulated audio >> and display it (see image). AFAIK this modulation is called FSK. >> The signal that is shown there should decode to data-blocks >> containing "11100000000" or something like that, are there any >> blocks in GnuRadio that can do that? Because the signal is derived >> from audio it is not complex but normal float, all GnuRadio >> demodulators seem to work only on complex data. Can somebody please >> help me? > >> Best regards, Stefan > > > >> _______________________________________________ Discuss-gnuradio >> mailing list [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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