Hi Tom,
> Well then, yes, it is modified.
Since the data are changed, can I say if measure the SNR from the data
after FFT, then they are inaccurate and bias?
Thanks,
Bin
On Thu, Feb 11, 2010 at 2:04 PM, Tom Rondeau <[email protected]> wrote:
> On Thu, Feb 11, 2010 at 6:52 AM, bin zan <[email protected]> wrote:
> > Hi Tom,
> >>I'm not sure what you mean by "modified." They have been adjusted by
> >>the sync block to fit in the middle of the FFT bins and the CP has
> >>been removed. Other than that, it's just the data stream.
> > Here "modified", I mean the data which enter into the FFT process are
> > different from the data if directly collected from usrp_rx_cfile.py. The
> > value of the remaining data (after sync and CP removed) have been
> changed?
> > If that's true, How can I match the original data ( same data obtained
> from
> > usrp_rx_cfile.py but without CP and unsync'd data) to the FFT bins?
> >
> > Thank you,
> > Bin
>
> Well then, yes, it is modified. The ofdm_sync blocks adjusts the
> frequency to make sure the subcarriers are in the center of the
> frequency bins for the FFT. If you don't do this, you introduce major
> ISI into the received symbol.
>
> Tom
>
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