[CQ-Contest] Contesting and the FT8 Revolution

Jeff Clarke ku8e at ku8e.com
Sat Jul 3 15:55:55 EDT 2021


You're exactly right about FT4. Joe probably wrote that code after he 
hooked up with some contesters (YCCC guys) who wanted to have a faster 
way to make FT8 contacts during digital contests. That being said there 
are very few stations that use FT4 during contests as most contacts are 
still being made on FT8. The reason for that is a good majority of FT8 
contacts you make during a contest aren't with contesters. You can still 
work stations for contest credit even though they aren't in the contest. 
You aren't going to find that to be true on the FT4 frequencies during a 
digital contest.

You are 100% right about FT8 being a great propagation tool.  I did 
watch CT1BOH's presentation on YouTube. In a VHF contest on 6 meters I 
always know it's time to go to SSB or CW when the dB of the stations I'm 
hearing are above zero.


On 7/3/2021 02:34 PM, Don Field wrote:
> With respect Jeff, that's simply not true. From the WSJT site:
> *The FT4 Protocol for Digital Contesting*
> * FT4 is an experimental digital mode designed specifically for
> radiocontesting. Like FT8, it uses fixed-length transmissions, structured
> messages withformats optimized for minimal QSOs, and strong forward error
> correction. T/Rsequences are 6 seconds long, so FT4 is 2.5 × faster than
> FT8 and about the samespeed as RTTY for radio contesting. FT4 can work with
> signals 10 dB weaker thanneeded for RTTY, while using much less bandwidth*
> FT8 is a different matter, developed for weak signal work, primarily on the
> 6m band,
> But Jose explained clearly in his original post why he thought there was
> benefit to be gained from studying propagation, etc. by way of FT8.
> Unfortunately the discussion has gone some way off the subject!
> Regards
> Don G3XTT
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> On Sat, 3 Jul 2021 at 18:12, Jeff Clarke <ku8e at ku8e.com> wrote:
>> Again for the umpteenth time... Why are people talking about this
>> subject on a CONTESTING reflector? Neither FT8 or FT4 are contesting
>> modes. I guess this is more proof that FT8 has totally taken over ham
>> radio? I guess people are really bored and can't help themselves? Hello
>> Mr Moderator can you please tell people to stop!
>> Jeff
>> On 7/2/2021 09:01 PM, David Gilbert wrote:
>>> I've gone through this stuff in detail with someone who knows far more
>>> about digital signal processing than either of us, and everything I
>>> said is possible with the exception that I will acknowledge that
>>> synchronous operation has advantages.  My postulation does NOT involve
>>> adhering to the FT8 or FT4 protocol as you seem to suggest below.  I
>>> proposed a mode similar to FT4 except wider bandwidth (which dose NOT
>>> necessarily degrade S/N as you claim) and a different set of other
>>> parameters ... plus conversion to CW instead of fixed text blocks
>>> simply to make it more adaptable to common contesting practice.
>>> I don't care what you say ... it can be done, but it's going to take
>>> somebody to work it up from scratch instead of trying to port FT8 or
>>> FT4 to a different user interface.  Just about everything you said
>>> below is wrong simply because you're stuck in that mental trap.
>>> I will say again since nobody seems to get it ... FT8 and FT4 as
>>> implemented by WSJT-X are not some new invention that locks all other
>>> similar efforts into the same set of boundary conditions that K1JT
>>> chose.  K1JT made very clever use of modern signal processing to
>>> create FT8, FT4, and other similar modes but he chose a VERY
>>> restrictive set of boundary conditions in order to implement his own
>>> particular vision.  Those same modern signal processing techniques
>>> could be implemented with different boundary conditions to give ham
>>> radio (and in particular contesting) a much cleaner and more usable
>>> interface.  Go read K1JT's descriptions of what he did and what
>>> techniques he used, and if you then do a bit of searching you will
>>> find lots of technical discussions of those same methods applied in
>>> different ways to other tasks.  WSJT-X is unique, but the the science
>>> behind it is not.
>>> I know that I am flogging a dead horse here, but it frustrates the
>>> hell out of me to see the opportunity that is being squandered simply
>>> because the guy that came up with the first popular manifestation of
>>> modern signal processing had such a limited vision of what it should be.
>>> Dave   AB7E
>>> On 7/2/2021 10:39 AM, Bill Coleman wrote:
>>>>> On Jun 21, 2021, at 2:59 PM, David Gilbert <ab7echo at gmail.com> wrote:
>>>>> Everything you just said there is the fault of WSJT-X as a user
>>>>> interface ... not FT8 or FT4 as a mode.  They are NOT the same
>>>>> thing.  WSJT-X is simply the narrow and restrictive vehicle by which
>>>>> we have been exposed to the exceptional weak signal capability of
>>>>> modern digital processing (forward error correcting, Costas array
>>>>> processing, etc).  We'd all be having a LOT more fun with a more
>>>>> open ended interface ... possibly with these parameters:
>>>>> 1.  wider individual signal bandwidth, such as maybe 200 Hz instead
>>>>> of 83 Hz.
>>>> A wider bandwidth would potentially decrease the sensitivity of the mod
>>>>> 2.  fully tunable over the typical digital sub band (like RTTY does)
>>>> There’s absolutely nothing stopping you from running FT8 or FT4
>>>> anywhere in the digital sub-bands. You may not have many QSOs there,
>>>> but it is possible.
>>>>> 3.  Asynchronous in time ... i.e., not locked to a discrete and
>>>>> specific clock window
>>>> This requirement is fundamentally incompatible to the way that FT8 or
>>>> FT4 work. The fixed transmission / reception windows are clearly a
>>>> part of the mode.
>>>>> 4.  shorter blocks of data with continuous feed of the blocks
>>>> Shorter blocks? The blocks today only convey 77 bits (BITS!) of
>>>> information. That’s right, it takes nominally 15 (or 7.5) seconds to
>>>> transmit 77 bits (BITS!) of information.
>>>> And continuous blocks don’t work either.
>>>>> 5.  sent via text blocks on the transmit end ... exactly as DVRs and
>>>>> contest loggers do now
>>>> Remember the 77 bits (BITS!) mentioned earlier? Each transmitted
>>>> block has a certain structure, and typically contains the two
>>>> callsigns (caller and callee) and a little bit of additional text.
>>>> There’s no much room for sending any random text, because there’s
>>>> only a few bits available to on each sent block.
>>>>> 6.  displayed as text or converted to audible CW (or even digital
>>>>> voice) on the receive end
>>>> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
>>>> Web: http://boringhamradiopart.blogspot.com
>>>> Quote: "Not within a thousand years will man ever fly!"
>>>>               -- Wilbur Wright, 1901
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