Re: [Discuss-gnuradio] BER over air

[Mostafa Alizadeh]

I finally got to this point that if one need to measure SNR, it means that he/she has to eliminate all the other channel effects as well as receiver uncertainties, (like fading, shadowing, Doppler shift, carrier frequency and phase offsets etc.) to have a correct estimate of SNR. Otherwise, he/she coudln't obtain signal-to-noise power ratio. 

Remember the received signal formulation I mentioned before: 

y(t) = h(t) * x(t) + n(t).

Thank you all. Any interesting ideas would be appreciated. 

Best, 

Mostafa

On Sun, Dec 28, 2014 at 10:53 PM, Iain Young, G7III <address@hidden> wrote:

On 28/12/14 19:08, Mostafa Alizadeh wrote:

Again I think we need to remove fading channel before SNR estimation. Is it
true?

To answer this specific point (and Marcus is far more better versed than I in this science):

More fading equals less signal, more noise at particular times, thus worse Signal to Noise Ratio.

If you need to be able to pass data during any fading, then you need
to take it into account (often this is done with FEC or PM schemes etc)

SNR is only "true" for a moment in time. The next moment, both signal
and noise may change.


Best Regards

Iain

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