Hi Bastian, Thanks for your reply. The peaks you mentioned is like the correlation result?
*Best Regards,Isen I-Chun Chao* On Sat, Nov 29, 2014 at 6:21 AM, Bastian Bloessl <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 >
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