Okay, I got it. One more quick question. I have been pretty confused about what the sync long and sync short are, respectively, responsible for?
Thanks. *Best Regards,Isen I-Chun Chao* On Sat, Nov 29, 2014 at 6:29 AM, Bastian Bloessl <bloe...@ccs-labs.org> wrote: > > > On 2014-11-29 12:28, Isen I-Chun Chao wrote: > >> Hi Bastian, >> Thanks for your reply. >> The peaks you mentioned is like the correlation result? >> > > Yes, exactly > > >> /Best Regards, >> Isen I-Chun Chao/ >> >> On Sat, Nov 29, 2014 at 6:21 AM, Bastian Bloessl <bloe...@ccs-labs.org >> <mailto:bloe...@ccs-labs.org>> wrote: >> >> Hi Isen, >> >> >> On 2014-11-29 07:01, Isen I-Chun Chao wrote: >> >> Hi, >> I am using gr-ieee-802-11 and putting a custom block, which is >> responsible for adding a 90-sample preamble at the head of >> incoming >> sample stream, right after the output of WiFi PHY Hier, as >> attached >> figure, generator.png. So the sample stream is changed as attached >> figure, adding_preamble.png. >> >> However, in the case of use of transceiver.grc, I can still >> successfully >> decode received data, which is keep printing out "Hello World!". >> >> Does anyone know why adding extra samples at the head of >> transmission >> samples does not affect the receiving results? Does it because >> somewhere >> in Rx side detect the OFDM preamble so the payload can be normally >> processed without being affecting by the extra samples placed >> before >> OFDM preamble? >> >> >> >> The sync long block does matched filtering with the long preamble >> and searches for peaks in a configurable window (sync length >> parameter). Looks like even if you add 90 symbols the peak that the >> block is looking for is still in the window. >> >> Best, >> Bastian >> >> >> > -- > Dipl.-Inform. Bastian Bloessl > Distributed Embedded Systems > University of Paderborn, Germany > http://www.ccs-labs.org/~bloessl/ >
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