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 _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
