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