Topband: FT8 qrm & Bandplanning History on 160m

Joe Subich, W4TV lists at
Thu Nov 30 09:16:50 EST 2017

On 11/29/2017 8:31 PM, Tim Shoppa wrote:
> Even narrower than typical CW. Yet we have CW signals interfering 
> with FT8 users self-perceived window, when they are 2kc away from
> each other.

As long as the CW operator does not decide to transmit "zero beat"
with an FT8 signal, there should be no interference from CW to FT8.
The issue comes in with FT8 operators who use equipment with limited
dynamic range and 2, 3, 4 or even 5 KHz bandwidth.  The problem is
no different that trying to work a DX/weak contest station adjacent
to a "local" QRO station.

FT8 operators can "see" the CW station on their display (although
they can't decode the CW in most cases) even if the audio is off.
CW stations can certainly hear the FT8 signal.  The two should be
smart enough to stay 300 - 500 Hz away.  If the FT8 operator can't
handle that, he needs to get a better transceiver (and get rid of
his new "broad as a barn" SDR POS) - the same goes for the CW Op.


    ... Joe, W4TV

On 11/29/2017 8:31 PM, Tim Shoppa wrote:
> Thing is, FT8 is by transmitted signal measurement, a narrow band mode just like CW.
> Even narrower than typical  CW. Yet we have CW signals interfering with FT8 users self-perceived window, when they are 2kc away from each other.
> So a regulation by transmitted signal bandwidth does not seem to be the magic arrow some of us thought a few years ago. I include myself in the “some of us”.
> Tim N3QE
>> On Nov 29, 2017, at 8:15 PM, Joe Subich, W4TV <lists at> wrote:
>>> 1) A few of us (myself, W4ZV and K1KI (I think) favored a true CW sub-band on 160M as we have always had in place on the upper bands
>>> like 80/40/20/15/10.
>> W8JI and I (then AD8I) also filed petitions with the FCC to create
>> a CW (narrow band as on all of the HF bands) sub band between 1800
>> and 1850 KHz.  ARRL refused to even give tacit support and the FCC
>> dismissed those petitions in spite of overwhelming comments in favor
>> of a narrow band only sub-band.
>> 73,
>>    ... Joe, W4TV
>>> On 11/29/2017 3:38 PM, k1zm--- via Topband wrote:
>>> Hi All
>>> This FT8 discussion is fascinating really.  It harkens me to remember the origins of the current ARRL 160M bandplan that we try to follow today on Topband.
>>> A number of us (myself included) were on the 160M ARRL BANDPLANNING COMMITTEE some years ago and there were several schools of thought that took place at the time:
>>> 1) A few of us (myself, W4ZV and K1KI (I think) favored a true CW sub-band on 160M as we have always had in place on the upper bands like 80/40/20/15/10.
>>> 2) However, the CHARTER of the ARRL committee was determined NOT to be inclusive of a formal petition to the FCC to establish true, formal sub-bands on 160M.
>>> 3) INSTEAD - the current bandplan was what was adopted which placed digital where it presently resides - as I recall it was on 1838 and not on 1840 by the way.
>>> 4) When those of us favoring FCC action on the matter inquired about CONTESTS - (especially those on SINGLE SIDEBAND) - we were told that 160M spectrum would "FLEX" to accommodate what would be SSB activity down to 1803 here in the USA and above 1813 over in EU since the lower band edge is 1810 over in Region 1
>>> In other words, if this is not cyrstal clear - it was EXPECTED that SSB would penetrate below 1842 during an SSB contest - and that CW would "FLEX" over the band segments that were usually considered for DIGITAL and SSB modes.during a competitive operating event.
>>> In actual practice this has worked reasonably well - until the rise of the interest in FT8 - where some folks seem to think now that 1838-1840 is somehow INVIOLATE.  This is an INCORRECT assumption in my opinion.
>>> No one 'owns" a band segment on 160M under what is a VOLUNTARY BANDPLAN - and the band segments do "flex" in contests when there is so much activity to warrant the overlap that naturally occurs.
>>> It is also an illusory assumption to believe that since the 160m band goes all the way to 2000khz that all space on Topband is of equivalent VALUE during a contest event. Europe, for example, cannot operate below 1810 and most European countries cannot run FULL POWER above 1850Khz.  Also some countries in EU today still are limited to narrow band slots from 1810 to 1830 or from 1810 to only 1850..  So it is quite LIKELY that during a contest event there is going to be a lot of operation around 1838-1842 and it is not likely to be FT8 either.if the contest is a CW event or an SSB event.
>>> What needs to happen (and usually does)is that after these contests are completed, the band FLEXES again back to our more normal, accepted conventions - meaning that CW is usually occurring from 1810 - 1835 or so (not by a rule - but just by gentleman's bandplanning convention) and that SSB usually occurs above 1843 or so.
>>> On a final note - W4ZV and I authored a FORMAL FCC petition after our 160M Bandplan service was completed and over 1000 amateurs worldwide filed supportive comments.  What we asked the FCC to do was create a TRUE CW sub-band on 160M from 1800 to 1835 or so here in the USA as I recall - but in the end Bill Cross at the FCC ridiculed the petition and the FCC denied it out of hand - which meant that what we have in place today is the VOLUNTARY 160M ARRL BANDPLAN that we now follow - and we all need to understand that NO BAND SEGMENT on 160M is reserved for anyone or any mode.  Here in the US, CW is authorized from 1800-2000 inclusive as is SSB - what we all usually do is try to respect what we have as a bandplan MOST OF THE TIME and not complain when a contest comes along.
>>> BY THE WAY - here's one for you.  I recently witnessed an HL5IVL digital qso where the HL5 was on FT8 around 1820 (because his 160M band was limited to 1825 and below) and the counterparty on this same qso was on 1840 or so on FT8.    I do nope we do not see too much of this kind of event - this one was understandable given the band restrictions in Korea.- but it would concern me to find FT8 all over the band all the time - because that would (most likely) create a lot of food fights going forward.
>>> At the end of the day - we must respect that 160M is a most UNUSUAL band and there are no really HARD ans FAST inviolate sub-bands in the traditional sense that we find on the higher bands.
>>> Personally - I am not an FT8 user - but I respect the rights of others to use this new mode.  We cannot hold back technology here - that never works very well - but we do need to understand the need to be FLEXIBLE - especially during competitive operating events (eg: contests).
>>> 73 JEFF   K1ZM/VY2ZM
>>> -----Original Message-----
>>> From: Ed Sawyer <sawyered at>
>>> To: topband <topband at>
>>> Sent: Wed, Nov 29, 2017 7:44 pm
>>> Subject: Re: Topband: FT8 qrm
>>> I'm sorry but I don't buy the argument that the way to be a "gentleman" is
>>> to accept everyone else's interests above your own.  A "gentleman" is
>>> respectful of others and treats others as he/she wants to be treated.
>>>   No one owns a frequency channel at least in the US - read your license.
>>>   If I come on a frequency, hear nothing, ask QRL using a legal and accepted
>>> mode for the frequency and hear nothing, I am using the frequency.  By the
>>> way - even the ARRL admits there is no longer a "DX Window" on 160M.
>>>   If FT8 is such a fragile mode to QRM that it needs a 2khz undisturbed
>>> window, then it is a flawed mode that will not stand the test of time in my
>>> opinion.  I am already starting to hear DX side people saying it's a
>>> complete waste of time and abandoning it.  I hear 3Y is going to try it -
>>> that should be hilarious.
>>>   I think that most of the FT8 crowd is horribly misinformed with dribble they
>>> read on the internet and think that some "net authority" has granted
>>> exclusive access to said frequency band and that they have had such right
>>> since June.
>>>   Look for me on 1840 in the ARRL 160 this weekend after listening, asking
>>> QRL, and seeing if I am disturbing anyone in my 400hz receiving window.
>>>   73
>>>   Ed  N1UR
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