[CQ-Contest] World Wide Digi DX Contest Results.

[Jim Brown]

On 1/13/2020 8:24 AM, Tim Shoppa wrote:
> In FT4/FT8 this meeting of minds is far more slippery and tenuous. This is
> completely inexplicable to those who have drunk the FT8 Kool-Aid because
> they trust the computer for all aspects of a QSO.

I strongly disagree with this analysis, Tim. There are other more likely 
causes, like RX noise, or poorly set up audio levels that causes weaker 
signals to fall below the level of the A/D converter in the Hound's 
computer sound card. This can combine with the reduced TX power for each 
stream sent by the Fox (6 dB reduction for each doubling of the number 
of streams) to make matters worse.

I strongly disagree with setup instructions in the WSJT-X operator's 
guide. The audio level indicated by the green bar is the top of the A/D 
converter; if a strong signal -- say 40 dB over S9 -- takes over the 
AGC, causing any signal weaker than 10 dB over S9 to fall below the 
level of the decoder!

Far better to set the green bar so that, with the strongest signals it 
stays as close as practical to the top of it's dynamic range (75-80 dB) 
but NEVER turning Red. Now, signals 80 dB weaker than that 40 dB over S9 
signal can be decoded. 40 dB is 8 S-units if you like 5 dB/S-unit, 
meaning you can decode an S2 signal, or almost 7 S-units if you like the 
6 dB/S-unit, meaning you can decode a signal between S3 and S4.

Without naming names, there's a little pistol station out here on the 
west coast who is seriously noise limited, and with whom I've 
coordinated as pilot for a 6M expedition to very rare grid CM79. He 
can't copy the expedition very well, even though they hear him well, and 
I've heard him having the same problems copying RR73 to him from HF 
DXpeditions.

Another contributing factor is the rigid "standard" for a QSO on VHF/UHF 
for weak signal operations like meteor scatter, moonbounce, and even 
E-skip, as articulated in the WSJT-X doc. The bottom line is that both 
sides of the QSO has to copy RRR from the other station; if the Hound 
hasn't copied RR73 from the Fox he continues sending his report and 
doesn't log it until he does. Properly operating, the Fox won't log a 
QSO until the Hound has stopped sending a report. The same practice 
should be followed in contest operation.

73, Jim K9YC