Topband
[Top] [All Lists]

Re: Topband: FT8 on 160m

To: topband@contesting.com
Subject: Re: Topband: FT8 on 160m
From: W0MU Mike Fatchett <w0mu@w0mu.com>
Date: Mon, 27 Nov 2017 16:19:11 -0700
List-post: <mailto:topband@contesting.com>
The normal bandwidth for FT8 is 2.5 to 2.8 kc.  at 1.842.9 you should have been outside the FT8 band.  Hardly anyone operates above 2.5 it seems anyway.  I think you  were essentially being trolled.  I suppose you could have been pretty wide for a local or close in station wiping out a fair portion of the upper end of the band.

I am usually on 160 FT8 every night but I took the weekend off for the contest from FT8.

Too bad the guy did not identify.  I noticed a few freq cops on the cluster announcements where some FT8 users think they deserve clear space which we know does not exist is a shared band that we have.

W0MU


On 11/27/2017 2:17 PM, Tim Shoppa wrote:
As a practical matter there are several 2 kHZ segments of each band that are now 
devoted to 24x7 JT65, FT8, and other digital modes. Weak signal CW work - eg working 
rare mults or even just weak guys from common mults - in those segments just 
isn’t gonna happen.

Substantial parts of 80M and 40M have been pretty bad for several years now 
with SAILNET and other automatic modes.

Tim N3QE

On Nov 27, 2017, at 3:43 PM, Roger Parsons via Topband <topband@contesting.com> 
wrote:

As we all know, CQWW produces huge activity on all HF bands. This year I was 
hearing stations up to well above 1850kHz. I have found that trying to run 
Europe is often more productive in the 1840-1850 segment, presumably because it 
is less crowded than lower in frequency.


Late in the contest I started to CQ on about 1842kHz, and after a while, and several 
QSOs, was told (on CW): "Please QSY. 1840 is reserved for FT8. Good luck in the 
contest." Ignoring the fact that nobody has a reserved frequency on any band, I 
thought OK, don't want to upset anybody, and moved to 1842.9kHz. Shortly, the same 
message arrived.

My (probably incorrect) understanding is that FT8 stations are using USB with a 
carrier frequency of 1840kHz. So a CW station on 1842.9 should be out of their 
passband. I did listen carefully and could not hear any FT8 transmissions above 
1842.2. (I have multiple receive antennas in a very quiet location.)

I believe that FT8 transmissions in principle use a microscopic bandwidth, but 
it appears they actually need a wide clear channel.

Yes? No?

73 Roger
VE3ZI
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband

_________________
Topband Reflector Archives - http://www.contesting.com/_topband
<Prev in Thread] Current Thread [Next in Thread>