I did the maths a while ago, and I'm confident the numbers are OK, but it's always possible mistakes were made. Feel free to investigate. The test cases would be a good place to go for confirmation.
Cheers, Martin On 09.11.2015 18:11, w xd wrote: > Hi, > > Thank you so much. > > I have test the block.And I find the block have delay fft_len-1. > > But in the example, rx_ofdm.grc you have delayed fft_len+cp_len.Is > it right? > > Best regards, > xd > > 2015-11-10 4:16 GMT+08:00 Martin Braun <martin.br...@ettus.com > <mailto:martin.br...@ettus.com>>: > > Hi, > > Is your fft length really 10? The gist of it is, the detection of the > sync burst will be delayed, and hence you also need to delay the signal. > The delay is caused by the averaging filters in the sync block. > > As for an example, rx_ofdm.grc should show you how it is connected. > You'll notice that the detection signal goes to one input of the > Header/Payload Demux and that triggers a capture. > > Cheers, > Martin > > On 08.11.2015 00:16, w xd wrote: > > Hi all, > > > > Thank you in advance.I‘'m so confused about the block > Schmidl & > > Cox synch, > > > > 1.I'm check the qa_ofdm_sync_sc_cfb.py to try to > understand the > > block. > > > > The original sequence: 5 zeros+4 cp_len+10 fft_len+14 data > > Just like this:[0, 0, 0, 0, 0, 1, -1, -1, -1, 1, 1, -1, -1, > > -1, 1, 1, -1, -1, -1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, 1, 1, 1, 1] > > The result of detect: > > (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, > 0, 0, > > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) 1 is in the position of 17 > > > > And in the example > > gnruadio/gr-digital/examples/ofdm/rx_ofdm.grc.You have add a delay > > block,and it delay cp_len+fft_len. > > > > According to this,after the delay,our original sequence > will be: > > 14 zeros+[0, 0, 0, 0, 0, 1, -1, -1, -1, 1, 1, -1, -1, -1, > 1, 1, > > -1, -1, -1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, 1, 1, 1, 1] > > > > Now we use the detect result to find the start point of the > > original sequence.we will find the start point: > > 14 zeros+ 0 +0 +0(the position of 17).......And I think the > > result may be wrong. > > > > Can someone explain it? Clear it. > > > > 2.How the above block cooperate with the block(head/payload > > Demux) to find the start point of the sequence？ > > > > Can someone use the above example to explain it? > > > > > > Thank you so much.I'm so confused about the design of the receiver. > > > > > > Best regards, > > xd > > > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org <mailto: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
