Hi, Besides using the Header Payload Demuxer as Julian suggested, a simple trick when the packet size is unknown but limited to a (not very large) maximum size is to cut a PDU with the maximum packet size and then throw away everything you don't need.
I have a CC1101 decoder in gr-satellites that does variable length packets using this trick. See https://destevez.net/2018/12/decoding-reaktor-hello-world/ Best regards, Daniel. El 31/12/18 a las 01:28, Julian Arnold escribió: > Hey Bob, > > there is plenty of documentation on this topic you can check out under > [1,2]. > Especially, the Header Payload Demuxer (HPD) [3] should be worth a look > if you are dealing with packetized variable length data. > > Hope those pointer can get you started. If you have further questions > after going through those pages, let me know. > > Cheers, > Julian > > [1] https://www.gnuradio.org/doc/doxygen/page_packet_data.html > [2] https://www.gnuradio.org/doc/doxygen/page_packet_comms.html > [3] > https://www.gnuradio.org/doc/doxygen/classgr_1_1digital_1_1header__payload__demux.html > > > On 31.12.18 01:00, Alban Meffre wrote: >> Hi >> I would like to decode a simple GFSK packet >> >> here is the packet structure : >> preamble : AAh x 4 >> sync word : D391h >> length byte : 1 byte >> payload : 1 to 64 bytes >> CRC : 2 bytes >> >> TX : arduino + CC1101 module, 2GFSK, 100kbps, excursion 50kHz, carrier >> 433 MHz >> RX : RTLSDR >> >> until now i was able to demodulate the signal and add a "sync" tag >> using the correlate access code. >> >> my goal is to extract the payload and send it to a file or a socket. >> is there a simple way to do that without writing my own block ? >> >> i can't go further, because i do not manage to find the info i need >> i do not know where to start : stream, tagged stream, PDU, messages, >> etc.. >> i do not figure out how to use these tag for variable length. nothing >> clear in the doc >> >> i'd be glad if someone helps me >> best regards >> bob >> >> >> >> _______________________________________________ >> 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
