[CQ-Contest] WW-Digi Contest -- Rule Clarification

Edward Sawyer EdwardS at sbelectronics.com
Wed Aug 7 06:56:21 EDT 2019

Am I the only one that is thinking "wow what a mess this is going to be" after reading this post?  Sounds accurate.  Sounds completely caotic.

I thought the mess on ARRL DX SSB on 40M was a mess.  That’s nothing compared to what this is going to sound like.  Except everyone's speakers will be turned off, so no sure what the digital equivalent looks like on the screen.

Ed  N1UR

-----Original Message-----
From: CQ-Contest [mailto:cq-contest-bounces at contesting.com] On Behalf Of Ed Muns
Sent: Tuesday, August 6, 2019 11:49 PM
To: 'David Gilbert'
Cc: 'CQ-Contest at contesting. com'
Subject: Re: [CQ-Contest] WW-Digi Contest -- Rule Clarification

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.


-----Original Message-----
From: CQ-Contest <cq-contest-bounces at contesting.com> On Behalf Of David Gilbert
Sent: 06 August, 2019 12:10
To: 'CQ-Contest at contesting. com' <cq-contest at 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 ...

Dave   AB7E

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