[VHFcontesting] FT4 Mode

[Mark Spencer]

I am glad someone else agrees with me about the potential effects of AGC  in this context (:

73

Mark S
VE7AFZ


mark at alignedsolutions.com
604 762 4099

> On May 2, 2019, at 3:55 PM, Chuck Dietz <w5prchuck at gmail.com> wrote:
> 
> I don’t use AGC on FT8 for the reasons you expressed plus that without it, you can decode weaker signals. After all, it is a weak signal mode. 
> 
> Chuck W5PR 
> 
>> On Thu, May 2, 2019 at 5:28 PM Mark Spencer <mark at alignedsolutions.com> wrote:
>> From a VHF contesting perspective I'm not completely convinced that all signals will always be decoded on a crowded FT8 "channel" with a mixture of very weak and very strong signals.   
>> 
>> I'm thinking receiver AGC (if it is used) and or the dynamic range of typical "sound cards" may lead to very weak signals not being decoded if there are very strong signals present at the same time as very weak signals ?
>> 
>> As I can't  control how other operators configure their equipment or what near by signals they may have to deal with, I am not hugely enthused about running FT8 from out of the way locations during contests as I am concerned my weak signals may not be decoded in practice during typical contest band conditions.
>> 
>> I am aware that some operators In out of the way places have tried running FT8 on "different frequencies" which in my view would go a long way to addressing my concerns but my understanding is most other stations were reluctant to QSY.
>> 
>> The opinions and experiences of others may differ from mine.   To be transparent I haven't put a huge amount of thought into this matter and if anyone fundamentally disagree with I have written I'd be happy to discuss further (preferably off list) in case I am missing something.
>> 
>> I suspect my use case may be rather unique.
>> 
>> 73
>> 
>> Mark S
>> VE7AFZ
>> 
>> mark at alignedsolutions.com
>> 604 762 4099
>> 
>> Mark Spencer
>> 
>> Aligned Solutions Co.
>> mark at alignedsolutions.com
>> 604 762 4099
>> > On May 2, 2019, at 11:19 AM, Michael Clarson <wv2zow at gmail.com> wrote:
>> > 
>> > Jay: The argument that SSB is so much faster than FT8/4 and stations should
>> > switch to SSB when the band is open is not universally true. It is if you
>> > are the station running guys on a specific frequency, but NOT if you are
>> > one of the poorer equipped calling the running station.  When running low
>> > power, it will often take 10 or more minutes to work a station on SSB when
>> > the band is open -- I am competing with many stations with better signals
>> > than me. But, on FT8/4, everyone gets decoded, and my rate actually goes
>> > up. --Mike, WV2ZOW
>> > 
>> >> On Thu, May 2, 2019 at 1:48 PM Jay RM <w9rm at calmesapartners.com> wrote:
>> >> 
>> >> The 'need for FT speed' reflects the huge QSO/hour disadvantage FT8 has vs
>> >> SSB when the band is open.  Many 6M op's have foolishly abandoned SSB
>> >> during contests, so the introduction of FT4 is an attempt to speed things
>> >> up a bit.  We'll see whether the mode can ultimately live up to it's
>> >> promise.  With all the mouse movements and click-click required, I doubt
>> >> FT4 will perform anywhere near as well as an experienced human op using
>> >> SSB.  We will see.
>> >> 
>> >> Remember,  FT4 is advertised as a 'contesting' mode.  The idea of a contest
>> >> is to maximize your score.  The best way to maximize a score is to run
>> >> contacts as fast as possible over the duration of the contest.  So, one
>> >> should use the fastest mode for the given conditions.  When the band is
>> >> closed or marginal, you want to use the most sensitive mode.  This could be
>> >> JT65 if the potential contact base is limited or FT8 if there are many weak
>> >> stations to work (or CW, of course).  As the band opens, there will be a
>> >> point where the intelligent operator needs to make a switch from
>> >> 'sensitivity' to 'speed'.  Should this switch be FT8 to FT4 ?  No, because
>> >> SSB is faster and certainly sensitive enough during a Es opening.
>> >> 
>> >> If this is the case, why does FT4 really exist as a contest mode ?  It's
>> >> not as good for weak signals as FT8 and it's most likely not as fast as
>> >> SSB.  "Because we can" is not a sufficient answer for something that has
>> >> shown the capability to totally upset the status quo of an entire band in a
>> >> negative way (condensing an entire band full of  operators on to what is
>> >> realistically one frequency).
>> >> 
>> >> -W9RM
>> >> 
>> >> Keith Morehouse
>> > 
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