A report in ANS-288 discussed an experiment
operating with the WSJT-X FT8 via satellite. Satellite operators have
gained more experience with this mode over this past week
As a result of on-the-air observation other
satellite users planning to try FT8 or MSK144 modes via satellite are
encouraged use caution using these modes and possibly avoid their use
completely in light of problems.
Dave, KG5CCI wrote, "He noticed a
very hard time getting into the transponder. The pass was nearly
overhead, and the 3w-4w that is normally sufficient was barely cutting
it. I also noticed it was 'up and down' alot, whereas some moments it
was easy to get in, then it would be nearly impossible. There were also
pockets of 'noise' all over the transponder, that sounded somewhat
digital, but I just couldn't place them." Further investigation revealed
that an MSK144 signal in the transponder passband was causing the
problems.
Matthew, NJ4Y noted,
"Experimentation isn’t the problem, too much power is. It’s bad enough
on SSB, worse with CW, and killer on constant duty cycle modes like
FT8."
To gain a full understanding of the situation
readers are encouraged to follow the amsat-bb message thread which can
be accessed at:
http://www.amsat.org/pipermail/amsat-bb/2017-October/064896.html
Source: AMSAT News Service
http://www.amsat.org/mailman/listinfo/ans
