Simulation of Sampling Clock Offset

On Aug 20, 5:55 pm, "mnentwig" <mnent...@elisanet.fi> wrote:
Hi Markus,

> there are two things that might get mixed up:
> - sampling clock offset (in terms of absolute time delay)
> - sampling frequency offset

Did not understand the difference. Can you please explain.

> The first is trivial in OFDM, it simply appears as frequency dependent
> phase shift inside the FFT. But the number of samples before / after the
> offset model remain the same.
hmmm...need not be. If the packet is long, the presence of sampling
clock offset
can result in drifts more than the sampling period.

> The latter may do real damage to OFDM reception, but is harder to model
Am unable to understand the difference between the first and second.

Thanks,
Krishna
http://dsplog.blogspot.com

Well...

imagine we compare time on our wristwatches today.
Mine is five minutes late.

We do the same again tomorrow:
case a) Still five minutes - the difference hasn't changed
case b) The watches have drifted further apart - maybe six minutes
difference.

OFDM is quite sensitive to case b) because the subcarriers lose their
orthogonality... the "O" in OFDM :) 

Cheers

Markus