Hi Jeon, in such a case, linking to the original file [1] including line number might be more helpful, as it gives more context.
So, looking at this, it's taking the delayed input samples and copies them (offset-corrected) to the output, considering parts of the samples, x = ignore, o = copy, starting at the frame start: oooooooo|xx¦oooooo|xx¦oooooo|... 128 |16¦128-16|16¦128-16|... I'm not too familiar with 802.11p frames, but that looks like Basti's leaving out some pilots in between the data, probably only copying the preamble and data payload. But I could be wrong. Greetings, Marcus [1] https://github.com/bastibl/gr-ieee802-11/blob/master/lib/ofdm_sync_long.cc#L128 On 05/09/2015 12:06 PM, Jeon wrote: > I am looking gr-ieee802-11 module. > > a part of the source code is pasted here > (https://gist.github.com/gsongsong/3df4553fe96e2d62b83e) > > I have a question on the following statement: > > `if(rel >= 0 && (rel < 128 || ((rel - 128) % 80) > 15))` in `case COPY` > `if(((d_count + o) % 64) == 0)` in `case RESET` > > I am wonder what do these numbers(128, 80, 15, 64) and modulo > operation have logical meaning in IEEE 802.11p PHY frame? > > I've read 802.11 OFDM specification, thus I have knowledge about it, > but I have no idea what are roles of these things in implementation. > > Regards, > Jeon. > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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