ARLA/CLUSTER: ARRL incentiva o uso dos modos digitais FT4 e FT8 nos seus futuros concursos

[João Costa > CT1FBF]

FT8 used in June VHF Contest

The ARRL Letter reports on the observations of WSJT-X Developer Joe
Taylor K1JT on using the popular digital mode FT8 in the June VHF
contest

The ARRL say:

WSJT-X developer Joe Taylor, K1JT, has tentatively concluded that
there are good reasons to use both FT4 and FT8 in ARRL VHF contests.
The latest beta version of FT4 was not available for the event, but
Taylor noted that FT4 will be available for future contests.

(the current -rc7 beta version will not be usable during ARRL Field
Day either). Taylor, who was active in the VHF event over the past
weekend, made the remark in a post to the Packrats reflector. Taylor
reported making 433 contacts (21 dupes) in 152 grids, all, by and
large, on FT8.

"Most of the time there was enough sporadic E and tropo-scatter to
keep things busy using FT8," Taylor observed. "In this event, meteor
scatter using MSK144 was not, score-wise, time efficient."

Taylor said he operated from home only on 6 meters and only on
digital, "mainly to see how FT8 plays in a June VHF Contest." He
operated for 21 of the contest's 33 hours and left his receiver
running on 50.313 MHz when not in the shack.

"During the contest period, I decoded 45,375 transmissions from others
in the 4 kHz window starting at 50.313 MHz," Taylor recounted. "That's
an average of about 11 decodes per 15-second receive cycle."

Taylor said he seldom, if ever, found that a single 3 or 4 kHz window
was "too crowded" with activity. "There were nearly always some open
spots, even with nearly everyone in the first 2.7 kHz of the window,"
he said.

Taylor also speculated as to how the twice-as-fast FT4 might have
fared, being 4 dB less sensitive than FT8 and having an 80 Hz
bandwidth instead of FT8's 50 Hz bandwidth.

"My guess is that something like 80 - 85% of my QSOs could have been
completed using FT4, most of them in half the time than it took in
FT8," Taylor said.

Source The ARRL Letter
http://www.arrl.org/arrlletter?issue=2019-06-13

The ARRL Letter archive, holding copies dating back to 2000, can be seen at
http://www.arrl.org/arrlletter