[Alexandria Radio Club Reflector] Why Use FT-4?

[Don (KI4D)]

After seeing the quote below in the current ARRL Contest Update, I got
interested in the source article in the October 2020 issue of Cheese Bits, a
newsletter published by the Mt. Airy VHF Radio in Abington, PA.  The quote
is from Joe Taylor, K1JT, the originator of WSJT-X, WSJT, and WSPR and other
ham programs. The newsletter, itself, is a great read and I thought worth
sharing.

 

73

Don, KI4D   

 

"From K1JT:  Thanks to Russ for an interesting summary of contest activity.
In my 80th year I can no longer call on my past stamina for contesting. But
as Russ wrote, it's always fun. I got on this time for about 6 hours, 6
meters only: 122 QSOs in 32 grids. All but about a dozen QSOs were with FT8;
the remainder were FT4. I'd like to make two points about mode choices in
VHF contests. 1. I fail to understand why anyone who uses FT8 in a contest
would fail to use FT4 for much of the time. FT4 is about 3 dB less sensitive
than FT8, but it's twice as fast. A large fraction of stations you work with
FT8 are much more than 3 dB above the FT4 decoding threshold. With FT4 you
can still work anyone that can be worked with CW, and near the CW threshold
you'll do it faster using FT4. And with FT4 you can work stations that are
far weaker (by ~20 dB!) than what's necessary for SSB. When I did work other
stations with FT4, I did it by transmitting the FT8 message "K1JT FT4 318".
I then QSYed to 50.318 FT4, and generally found several people followed me
there. Many more would have made it much more fruitful! 2. When I'm
operating with FT8 I often check the PSK Reporter map to see where I'm being
copied. During a contest, on 6 meters, my KW and 7 elements are typically
copied in most locations within 1000 miles or so. This is with the band
*NOT* open. It's the background ionospheric scatter signal that's being
copied. Stations in these locations can definitely be worked, though it
takes some dedication to do it. Often it's QSO times of 15 minutes or so,
copying on the scatter QSB peaks. FT8 is not optimized for the sort of QSB
that ionoscatter creates. We may come up with a digi-mode better suited to
such propagation, and it could be very useful for working new grids during
otherwise slow times in a VHF contest. Summary: for speed, flexibility, and
ease of running the bands, yes, you should use SSB and CW when there are
stations to work. When you run out of those, use FT8 and (especially) FT4.
And when the going is slow with standard uses of those modes, consider
working ionoscatter for new multipliers."

 

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