Note: As of Version 9 WSJT ISCAT replaces JT6M. Note from K1JT...
This is a request for some specific feedback from WSJT users.
As I understand things the JT6M mode is still widely used in EU, despite
having been replaced (in WSJT 9.0) by ISCAT -- a mode with significantly
better performance.
1. Is my understanding correct?
If so, I hope some users will offer their explanations of why this might
be so. For example:
2. Are some users skeptical of my statement that ISCAT has
"significantly better performance"?
3. Has it been hard to get people to change, because they like a
familiar way of doing things?
4. Something else?
I ask these questions, in part, because ISCAT should be a superb mode
for making inter-continental QSOs on 6 and 4 meters under marginal
propagation conditions likely to be more common in coming months.
One good example: recently SV8CS worked ZS6WAB on 70 MHz using ISCAT,
via TEP.
Another example of an unexpected and very fruitful use of ISCAT: VK7MO
and VK3KH have been making 500+ km QSOs at 10 GHz, using aircraft scatter.
ISCAT is a powerful mode. In a number of ways its capabilities are
complementary to FSK441, JT65 and JT4. Under all relevant propagation
circumstances I've been able to document, ISCAT performs better than JT6M.
Soooo..., once again, can someone please clarify the ISCAT-vs-JT6M
situation in Europe for me?
Am I misinformed? Is a transition to ISCAT simply taking longer than I
might have expected? Or are there other considerations that I should
know about, but don't?
-- 73, Joe, K1JT
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The following is good reading, just be aware that JT6M is replaced
with ISCAT and JT6M should no longer be used since we all should be
interested in using the better mode!
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Subject: [wsjtgroup] Question about JT6M
I worked John W9SE, in Illinois about 1630 UTC, JT6M, 50,260.
Now we are in Es season (beginning), but I thought JT6M was
HSMS prop mode for weak signals?
How to tell the diff?
Mark Lunday
WD4ELG
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Hi Mark,
Actually JT6M is more suited to Es than to MS. The rate is too low for most MS.
In other words most MS pings are too short to support JT6M but will work just
fine with FSK441 which is faster.
That's not say you can't make an MS contact using it if the rox are large and you
get a long enough burn.
You'll find during Es season that you'll work a lot of stations with JT6M when the
band is open. And don't forget to check 50.230 when the band is open to Europe
as there is a tremendous amount of JT6M activity over there.
Looking forward to working you when we get some Es.
Hope this helps.
Cheers,
Barry VE3CDX/W7
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Re: [wsjtgroup] Question about JT6M
Just to add a little to what Barry wrote earlier --
Trying to figure out what combination of propagation modes you're seeing is, to me,
one of the more fascinating things about doing WSJT on 6 meters. Since the Magic
Band supports, at one time or another, almost every propagation mode known, it
provides us with a real guessing game! One of the cool thing about WSJT, of course,
is that you get a visual rendition of the signal, and this can really help figure out
what is happening.
Because of the prevalence of sporadic-E propagation on 6 meters during the summer
and winter seasons, it is pretty common for any kind of propagation that doesn't look
like a meteor ping to get labeled as sporadic-E. Sometimes it undoubtedly is, but often
it's something else. If it's not sporadic-E season (roughly early May to late August) and
there have been no reports of unseasonal sporadic-E in your area of the country, then
what you're seeing is probably not sporadic-E. Some of the other things it could be:
When ground wave is enhanced by tropospheric propagation, distances can be worked
out to several hundred miles. Tropo usually is characterized by a very slow up-and-down
QSB, with as much as a minute or two between peaks. On top of the slow QSB you will
often see a fast QSB, where the signal appears to pulsate from about 1 to 5 times per
second. The pulsation period also can vary slowly. The strength of tropo-enhanced
signals can be anywhere from a mere whisper to quite strong, but the QSB
characteristics described usually hold.
D-Layer Ionoscatter is a mode that many folks may be unfamiliar with. This is a
weak-signal mode that can best be exploited either with JT6M or with one of the
EME modes; JT65B (normally used for EME on 2 meters) has proven to be especially
effective on 6-meter ionoscatter. When you see a somewhat steady but very weak "floor"
to a signal punctuated by meteor pings, the "floor" signal is usually either tropo or
ionoscatter, depending on distance. Since the D-Layer is much higher than the
troposphere, propagation distances up to 1,000 miles can be obtained using this
mode. A more typical distance range is 300 to 600 miles.
Meteor pings... There are many, many different kinds! Some of the things that affect
what a meteor ping "looks" like probably include the meteor's mass, its composition
(metallic or rocky), its degree of solidity or structural integrity, its entry speed, its entry
angle with respect to the atmosphere, its entry angle with respect to your location,
and so on. The ion (plasma) field generated by a meteor can disappear within
milliseconds, or it can persist for many seconds, occasionally even for minutes.
So don't assume that propagation persisting for 20 or 30 seconds is "sporadic-E";
more than likely, it's just a really good rock! Meteors exhibit a variety of different
waterfall traces, and I'm starting to work on creating a library of different trace
classes -- but that work is just getting underway.
During sporadic-E season (which is just getting started as I write this), contacts
can be made using JT6M. When sporadic-E is strong, it is indistinguishable from
a nearby ground-wave signal. Even a weak sporadic-E signal will look and feel much
stronger on JT6M than it would on SSB! JT6M is an ideal transmission mode for
weak-signal multi-hop sporadic-E.
What about aurora? Since I live in New Mexico, I've never had the opportunity to
visualize an auroral signal on the WSJT waterfall. I'd love to know what it looks like.
The phase distortion inherent in auroral propagation, though, probably makes any
WSJT mode effectively useless for actual communication. (If I'm wrong, tell us of
your experiences!)
Bill W5WVO
PS -- Yeah, I know, I neglected to mention F2. Well, since F2 is probably at least four
years out on 6 meters, I figure we have some time on that one!
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RE: [wsjtgroup] Question about JT6M
Bill, as usual, has done a superb job explaining various propagation modes Mark.
And, you will experience most of them at one time or another on 6 meters. I say
most because unless you are using a ground mounted vertical you will not experience
ground wave propagation. And if you do then chances are pretty good the other
station will also be using a ground mounted vertical or else you are very close to
each other. A few miles at most. Ground wave propagation is vertically polarized
and is a very low to medium wavelength mode. Typically you will find it from 30 kHz
to roughly 30 MHz although at the high end it isn't very efficient because of the
higher inherent loss in the earths surface.
The Navy uses it for example to communicate with submarines in the 100 kHz range
and your local AM broadcaster uses it as well. Of course there is a sky wave
component from a vertical that comes into play but that relies on reflection from
the various different layers. That's a whole different topic.
Like Bill I live too far south to get any Au but knowing what that does to a SSB
signal I have to agree that any of the WSJT modes will probably not work.
Barry VE3CDX/W7