[Lowfer] QRSS sensitivity versus signaling speed

[Garry and Linda Hess]

In regard to the January 12, 2009 question raised by Paul Daulton, the 
following URLs are relevant: : (1) 
http://www.wireless.org.uk/signoise.htm and (2) 
http://www.scgroup.com/ham/wolf.html.

The pertinent results in reference (1) are: QRSS60 advantage over QRSS10 
= 8dB; QRSS10 advantage over QRSS3 = 7.6dB; QRSS3 advantage over 12wpm 
CW = 12dB. The net advantage indicated for QRSS-60 over CW is thus 27.6 
dB. Of course that will be a strong function of the character of the 
noise floor; i.e., is it smooth and Gaussian or rough and impulsive due 
to lightning, etc.

Reference (2) indicates 0.4 words-per-minute (WPM) QRSS  has a 12 dB 
advantage over CW. But this is QRSS-3 since the standard for code is bit 
duration = 1.2/WPM and interestingly 12 dB is exactly what reference (2) 
found. WOLF-10 is found to often work to 45 dB below the noise power, 
which is 27 dB better than CW and therefore comparable to QRSS-60. But 
in fairness to WOLF-10, it conveys a larger message and does so with 
confidence, not biased by knowing in advance what one wants to see.

73,
Garry
K3SIW, EN52, Elgin, IL