On Feb 16, 2011, at 2/16 8:05 AM, N2WQ wrote:
> So, recognizing that I have a few other improvements to make, what
> should I expect from extra 3db SNR on RTTY?
It will depend on band conditions.
Again, take a look at Alex VE3NEA's measurements here:
http://www.dxatlas.com/RttyCompare/
The first plot for AWGN represents perfect band conditions in the
presence of only noise. Look at the horizontal axis. Notice that a 3
dB change can take you from good copy (3% character error rate) to
gibberish (30% character error rate).
So, 3 dB better SNR will take you from a useless signal to one that
prints much better than you would need in a contest that allows you to
repeat an exchange.
Now scroll down to the Selective Fading plot.
Notice that it now takes about 13 dB to cross this decoding
threshold. So, a 3 dB bump in the SNR is not very useful. 3 dB
improvement can get you from gibberish to ...umm... less gibberish :-).
73
Chen, W7AY
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