Hi Dave,
I don't think using 14.101 USB is the main reason for QRM on the 20m NCDXF
frequency. But some guys were definitely using ROS on 14.098 which was very
silly.
I agree - I think the ROS waveform starts around 400Hz so I would expect the
lowest ROS tone to be about 1400Hz higher than the NCDXF CW frequency.
With a 500Hz narrow filter certainly it would be far enough away but I suspect
that many of the monitoring stations might be using a wider bandwidth,
especially the automatic monitors. I know for a fact the FAROS program requires
a wider bandwidth than 500Hz and I remember reading somewhere it needs about
2KHz for optimal detection of the NCDXF signals. I don't know the reason why
but if so then it is conceivable that ROS on 14.101 is indeed causing a problem.
My horse in this race is that ROS on 14.101 USB does interfere with our packet
network on 14105 LSB. It's just the few top tones of ROS but they unfortunately
coincide directly with our packet tones.
I believe the modes you allude to (TOR and Packet) are most likely WinMOR (the
TOR mode) and perhaps APRS beacon packets. I too have unfortunately heard
WinMOR stations also way too close to the NCDXF frequency. They are not regular
however so maybe someone just picked the wrong frequency for testing?
I am not 100% sure about the APRS but I recently read something about a UK
based 20m APRS experiment and remember thinking they may be a little close to
the NCDXF frequency but I can't seem to find any information on it when I just
Googled it so can't tell for sure. Unfortunately I can't hear them from this
QTH on the West Coast of the USA.
But thinking about the very wide bandwidth of ROS (wider than ALE even)
wouldn't it make sense to come up with a "channelized" system of ROS on higher
frequencies perhaps >14.115MHz but <14.150MHz ? There's no need for ROS to be
in the automatic segment at all. If I was interested in ROS I would be tempted
to propose different "Channels" for the US (if deemed legal), Pacific/Asia,
Australasia and the EU. That would also help with the many ROS signals all
competing on the same frequency. It would just take a little coordination
between interested ROS users (and understanding of the international
allocations) but you guys could have some pretty effective DX communications on
those higher frequencies where QRM is much less anyway.
Just my 2 cents.
Sholto
K7TMG
--- In digitalradio@yahoogroups.com, Dave Ackrill wrote:
>
> Tony wrote:
> > Sholto,
> >
> > The silence is deafening...
> >
> > I'm sure there are some who may be unaware of the the NCDXF beacon network
> > ( www.ncdxf.org ) but there's no excuse for the deliberate QRM I've
> > witnessed. I'm very surprised...
>
> I, personally, don't use 14.101MHz and have been trying to persuade
> people to move up the band a bit anyway. So, the deafening silence has
> been the art of persuasion rather than big boots stomping up and down on
> a new experimental mode.
>
> I do hope that you will be figuring out who and what that packet or TOR
> mode is that is below 14.101, and nearer the beacon frequency and
> stomping on that as well?
>
> In fact, if ROS is on a dial frequency of 14.101MHz, and like most
> digital modes it transmits HF of that frequency by some offset, probably
> about 1.2kHz or so, wont it be far out of the passband of even a
> wide/normal CW filter? If so, please explain how you are so sure it is
> ROS that is causing a problem. Even if the '1st tone' was some 400Hz
> above the dial frequency, that is still 1.4kHz, and only transmitting
> that 400Hz tone infrequently, so, again, I would have thought way above
> a 'standard' CW filter width...
>
> Dave (G0DJA)
>
