There is growing trend on 160 that I find disturbing and that is for
major DXpedition to use FT8 for all or mostly all 160 operations. They
do that because they "know" that FT8 is ideally suited for weak signal
operation. They have read that and are continually told that by
everyone. Rare countries on 160 is synonymous with weak signals and
poor signal to noise ratios.
I know of no one that has done the same tests that I posted to Topband.
I have had people agree with me but that was because they liked my
answers, not because it agreed with their measurements. I have had many
people tell me I am wrong and they sited the official documentation as
proof that my measurement were wrong.
So if you would like to join the ranks of myth busters, start doing some
measuring. WARNING, Myth busting of all types in ham radio is a never
ending effort. As soon as you bust one, two posts later someone will
repeat it again. Sorry, I don't have any caps, pins, or t-shirts to sell.
If enough people start characterizing this mode maybe the more
experienced people in radio will sit up and take notice. One or two
posts by a single person isn't going to do it.
You are not going to kill FT8 no matter what you do or how feel about
it. It will always be a home for those they can't copy CW, and for
those that don't like CW, and for a few others for a variety of
reasons. I can't see a problem with that. The problem I see is with
FT8 and major DXpeditions. I also see some FT8 only DXpeditions but
those are usually vacation part time to non-rare countries. Can't worry
about those.
For people that can't copy CW, FT8 is very attractive. It will allow
them to work some DX on 160. In the winter I see Europe appearing on
FT8, so that can be worked from the eastern US. Invariably when I
measure the strength of those stations, they are close to S6. That
would be arm chair copy on CW with a receiver that sits on S1 on noise.
So contribute to the ham radio knowledge data base by making some
measurements. I described my measurements in a previous post. Figuring
out what the reported S/N number means is interesting but the more
important question is what is the minimum signal to noise ratio this
mode will decode. Sitting up a test for minimum signal is a little
tricky because there are so many FT8 stations on at any one time, there
is almost never a nearly dead band. I simulated that on 160 by waiting
until the first stations from the NE showed up on the band (just after
their sunset) and turning my antenna away from them so as to decrease
their strength and bring up the noise from other directions. When I
wait until sunset occurs in more locations, my S meter hangs at about S9
+20 to 30 dB no matter which direction I point my antenna. I tried
doing this on 6 meters but often there was nothing there. I suggest
doing measurement first in normal decoding mode, then test what it does
in deep search mode. Be careful how you switch modes. FT8 likes to
memorize the band and make guesses in deep search mode.
You can try doing the minimum S/N test in a crowded band instead of a
nearly dead band but I don't think you will ever find it decoding a weak
signal. You have to measure the noise levels and signal levels. You
can't use the reported S/N number.
If you make some measurements, post them. I would really like to hear
what others find, especially if they happen to disagree with what I
measured.
I don't have a pony in the dog and pony DXCC race so I don't have an
opinion there. I love working DX on 160 but collecting cards was no
fun. So years ago I decided to only do the fun part. I compete with
myself, no one else, and I don't get bragging rights, but I don't do
this for bragging rights.
Jerry, K4SAV
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|