Re: LF: Re: Slow mode comparisons

[MarkusVester@aol.com]

Dear LF Noise-Diggers,

Alan said:
> The swap from QRSS3 to QRSS10 is an advantage of about 3dB also.

Alberto said:
> the FFT bin size is 4 times smaller, and this results in an increase of 6 dB of SNR.

My half-penny's worth is that the transmitted energy per symbol is 3.3 times larger, giving exactly 5.23 dB improvement ;-) That's assuming that the FFT bandwidth is somewhere near the optimum (0.3 Hz and 0.1 Hz respectively). I'd go with Alan in that DFCW is more reliable than QRSS, even more so when comparing readability at a given WPM throughput.

Selecting the right symbol time for an opening of limited duration is certainly intricate, as shown by last night's ZL-VA attempt. The peak SNR in Scott's image would probably have allowed higher speed, but how do we know if its going to be "short and strong" or "long and weak" tomorrow?

Funny thing about the delay on this reflector; I got a pile of mail after 14:08 this afternoon.

I wish you success and good luck.

73 de Markus, DF6NM