On 30.04.2014 11:51, David Halls wrote:
Hi Martin, All,
Has anyone noticed that the final symbol of any burst (no matter how
many packets in a transmission) appears slightly 'noisy' in the OFDM
example code? Is it something to do with my set-up?
I attach a picture of the eq'd FD constellation when I send two packet:
a) the first packet, b) the second packet (excluding the final (16th)
symbol), and c) second packet (with all symbols)
Is it to do with sample alignment/timing error? I have tried sliding the
samples passed to the FFT at the receiver, moving the window backwards
and forwards and can't get a better result...
This was my first thought when I read the subject line... where are you
getting symbols? Before the equalizer? And is this OTA, or simulated?
Really, all OFDM symbols should be equally noisy. A timing offset will
normally only make the acquisition start somewhere between start and end
of the cyclic prefix. So, I'm unsure what this is without any further
analysis.
Martin
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