Then why don't the WW-Digi rules simply state that such operation
(multiple QSOs on the same band using Fox/Hound mode) is not allowed.
Most contesters are NOT going to be aware of, or maybe not even care
about, any splatter caused by their own operations. Most FT8/4
operators have no easy means of monitoring their own transmit quality,
and that should be obvious from watching the spectrum display at almost
any time of day or night.
Expecting participants in the contest to understand that they shouldn't
use Fox/Hound based upon the webinar doesn't make much sense. You'd be
lucky if a third of the participants in the contest even watched the
webinar. They're going to (hopefully) go by the written rules, which
currently do not specifically outlaw multiple simultaneous signals, and
that means that people familiar with Fox/Hound mode are going to be
inclined to use it. You specifically say below that multiple parallel
QSOs WOULD be OK if they didn't use Fox/Hound to achieve it ... so why
don't your rules simply say that?
I disagree that Fox/Hound is the only way to transmit multiple signals
at the same time. I'm pretty certain I could do it with multiple rigs
and running multiple instances of WSJT-X (which WSJT-X allows) on the
same computer. All it would require is different com ports and rig
assignments for each instance of WSJT-X, and the outputs would be
independent and therefore clean barring any nonlinear combining of RF
past the rigs.
I just don't understand why you don't write the rules to clearly
prohibit that which you don't want to happen. It's like you're posting
a DO NOT ENTER sign on the back door of the building.
73,
Dave AB7E
On 8/6/2019 8:48 PM, Ed Muns wrote:
This is an example of the DXpedition "Fox and Hound" mode where the DXpedition
station is the Fox and transmits 2-5 distinct audio frequencies within his TX passband
using a single suppressed carrier at the radio dial frequency.
The WW Digi rules are written to allow multiple parallel QSOs. This is
appropriate for this narrow-band multi-channel signal technology. As of today,
the only technique I'm aware of for achieving this is the Fox and Hound mode
described above. However, in a multiple-Fox scenario like contesting, this
method of parallel QSOs is unacceptable.
The reason is that two or more audio signals are effectively transmitting a
Two-Tone (or Multi-Tone) IMD test on the band. The narrow, vertical-skirt FT
signals are thereby turned into wide, flared-skirt signals that will QRM
neighboring QSOs on both sides. In the DXpedition scenario with just one Fox,
that IMD can be contained in a small area of the pass band, say 400-500 Hz,
while all the DXers (Hounds) calling in can spread out in the rest of the
passband.
In a contest scenario where there will be many Foxes, all trying to increase
their QSO rate, the FT sub-band will be wall-to-wall IMD QRM. This is a
flagrant betrayal of the exceptional signal design in the basic FT GFSK signal.
Not to mention unsportsmanlike operating in general.
Therefore, the pertinent WW Digi rule is:
XII.A.5. Poor signal quality that interferes with other stations’ ability to
operate. This includes, but is not limited to: signals with excessive bandwidth (e.g.,
splatter, clicks, IMD), harmonics on other bands, and excessive audio levels.
One purpose of this rule is to rule out the current Fox and Hound method in WW
Digi, among other signal quality issues like overdriving the TX audio. It is
easy to spot parallel QSOs in a log and any such cases will be reviewed with
SDR recordings. Don't use the current Fox and Hound implementation in this or
any other contest. Some of the software packages don't allow Fox and Hound
mode when the contest mode is selected, to help participants follow the rules.
The WWROF webinar the past Sunday, replayed Monday evening NA time, explained
this with spectrum images of clean and ugly FT signals. The presentation PDF
is linked from the WW Digi home page, and the webinar video recording will be
linked there and on the WWROF webinar archive page later this week.
Ed W0YK
-----Original Message-----
From: CQ-Contest <cq-contest-bounces@contesting.com> On Behalf Of David Gilbert
Sent: 06 August, 2019 12:10
To: 'CQ-Contest@contesting. com' <cq-contest@contesting.com>
Subject: [CQ-Contest] WW-Digi Contest -- Rule Clarification
Although it is certainly implied, the rules listed on the WW-Digi
website do not specifically prohibit using more than one signal at the
same time ON THE SAME BAND for the single op category. They say that
transmission can only be on one band at a time, but they don't say you
can't make multiple transmissions at the same time on the same band.
The reason I bring this up is that I just witnessed 5T5PA making three
separate FT8 transmissions on 20m to three different stations all within
the same fifteen second window. A short time later I saw two separate
transmissions from him to two different stations (and different stations
than the previous three), again all within the same fifteen second
window. Each simultaneous transmission was spaced exactly 60 Hz apart,
and the software cleanly decoded all signals as if they were from
different callsigns. 5T5PA expertly managed all the QSOs cleanly.
Interestingly enough, even though I've worked 5T5PA before, JTAlert only
labeled one of the three as a dupe.
I can think of more than a couple of ways 5T5PA could be doing this, and
for casual operation I see no problem with it. For a DXpedition, it
might even make a lot of sense. I don't remember it being against
FCC/other laws, but I could be wrong about that. In any case, it seems
to me that it could open up the possibility for some controversy in a
contest.
Or maybe I'm just crying wolf here ...
73,
Dave AB7E
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