Ahh-- my mistake, I was assuming the "dips" were something like one symbol, the other being the continous wave with the 400u amplitude, and completely missed the differences in period on the non-dippy signal... The lower halfwaves of the lower-frequency oscillations look a little strange; maybe this signal was generated by RC-lowpassing a PWM signal?
On 16.07.2014 15:18, Martin Braun wrote: > 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 Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
