WSJT-X Developer Posts Observations On Using FT8 In June VHF Contest

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 <packrats@mailman.qth.net>reflector. Taylor reported making 433 contacts (21 dupes) in 152 grids, all, by and large, on FT8.</packrats@mailman.qth.net>

“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