Topband: FT8 qrm

Dave AA6YQ aa6yq at ambersoft.com
Wed Nov 29 12:59:30 EST 2017


1. I operate both CW and FT8 on 160m, and am far from unique in that regard.

2. WSJT-X, the application many FT8 ops utilize, includes a waterfall display that shows CW signals

3. WSJT-X gives its users control over where they transmit, so a "pre-existing" CW signal can be avoided

4. WSJT-X could be extended to be able immediately stop decoding FT8 (or JT65) signals and send QRL in CW at a frequency designated by clicking in its waterfall; many FT8 users employ relatively low power with modest antennas, however, so this may not always be effective.

5. It's not unreasonable to expect competent ops to be aware of what modes are typically used in what segments of a band, and to listen for an appropriate length of time before first transmitting to ensure they don't QRM an ongoing QSO.

      73,

          Dave, AA6YQ

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Tim Shoppa
Sent: Wednesday, November 29, 2017 7:53 AM
To: Wes Stewart
Cc: topband at contesting.com
Subject: Re: Topband: FT8 qrm

You don�t understand how the FT8 guys work. They have a 2kHz slice they all work in whether they were there first or not by usual CW practice. They only transmit every 30 seconds and no CW operator is gonna wait a whole 30 seconds for a response to QRL?.  Not that a FT8 guy can respond to a QRL anyway. The vast majority of FT8 guys do not operate CW anyways.

So that 2kc slice it�s not a matter of who was there �first� by CW standards. The FT8 guys have been there since June of this year and to them, June is when they were there first.

And if a CW guy fires up 1-2kc away from a weak warbly FT8 carrier,  he thinks nothing of it. And if the CW guy is anywhere in the wide 2kc FT8 slice then all FT8 operators will regard it as QRM that renders the entire slice worthless.

It is odd that we have two fundamentally narrow bandwidth modes yet they do not coexist well. It�s ridiculous to think they could coexist in a contest weekend anyway. Those FT8 guys that were rudely surprised by CW this past weekend, that�s nothing compared to what�s gonna happen this coming weekend.

Tim N3QE

> On Nov 29, 2017, at 7:29 AM, Wes Stewart <wes_n7ws at triconet.org> wrote:
> 
> My scenario had the CW man on the frequency FIRST.
> 
>> On 11/29/2017 4:54 AM, Tim Shoppa wrote:
>> A typical CW guy will hear FT8 or JT65 as a kinda whiny wobbly intermittent carrier. And will probably think it�s just some neighborhood switching power supply noise. He won�t CQ right on top of it (because he wants to hear a DX respondent) but he will have no problem firing up 500 Hz away.
>> 
>> But the digital guys e.g. FT8 have 2khz wide filters. So there is a fundamental assymetry here.
>> 
>> Tim N3QE
>> 
>> 
>> Sent from my VAX-11/780
>> 
>>> On Nov 28, 2017, at 10:50 PM, Wes Stewart <wes_n7ws at triconet.org> wrote:
>>> 
>>> So what's the protocol when a CW man checks a frequency, hears nothing, sends a couple of QRL? and hears nothing and begins to run stations.  Then sometime later a guy running an imaginary mode...oops...sorry, FT8 shows up and wants to park on the CW man's frequency?  Who is to blame?  I'll answer my own question: the FT8 guy who is QRMing an occupied frequency.
>>> 
>>> Besides the FT8 guys can always resort to JTAlert to QSO via text messaging as one west African station apparently tried to do with me.
>>> 
>>> Wes  N7WS
>>> 
>>> 
>>>> On 11/28/2017 10:45 AM, Bryon Paul Veal N�AH wrote:
>>>> There were ops all over the FT8 segments, refused to even try and work them and some were some pretty rare mults for CQWWCW...gentleman agreements are of the past.....sucks
>>>> 
>>>> PAUL. N0aH
> 
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