>>>AA6YQ comments below
--- In digitalradio@yahoogroups.com, "Jose A. Amador" <[EMAIL PROTECTED]>
wrote:
>snip<
There are physical mechanisms in radio propagation that creates
hidden stations. So do losses, distance, natural obstacles, and
finite propagation paths. I even had thought it was a well known and
accepted fact by knowledgeable people. But seems it isn't, at least,
yet.
>>>If you check this reflector's archives, you'll find messages from
Steve K4CJX, a member of the Winlink team, claiming that there is no
hidden transmitter effect.
>>>Yes, hidden stations are absolutely a fact of life on HF. Why then
would anyone deploy an unattended station that relies on a remote
initiator to ensure a clear frequency when this scheme clearly fails
in a hidden station scenario?
>>>Your argument seems to be "because there can be hidden stations,
its okay for unattended stations to QRM them".
>snip<
Radio has been proved not to be an ethernet backbone on which
everybody hears everybody all around the world.
>>>Agreed. And so deploying unattended stations whose considerate
operation requires that everybody hear everybody is irresponsible.
Automatic stations do have a place in the bandplans, so, if automatic
stations stay in those segments, I don't see reason, exception made of
emergencies, if any, to go there where the automatic stations are,
in any other mode and sit there. At least, in the well connected and
informed developed world. Nobody in his right mind sits between the
railroad tracks. Doing otherwise is sort of cheap irrational old west
bragging. In such a case, if the train overruns you, you have no
right to cry.
>>>Railroad tracks are an indisputably obvious marker, and their
right-of-way is owned by the railroad; if you camp on railroad tracks
and are struck by a train, its your own fault. There are no such
obvious markers on frequencies in which unattended operation is
permitted, the frequencies available for unattended operation vary
from region to region, and these frequencies are not exclusively
allocated to unattended operation. No unattended station can QRM a
pre-existing QSO on the grounds that it "owns the right-of-way".
Even when an activity detector such as what SCAMP has tested, and has
been documented to work fairly well, as far as I know the code is not
in the public domain and noone has either convinced the author to
publish it or stepped forward to write out of scrap and openly
publish a viable substitute for all possible cases.
>>>There is no secret sauce in the SCAMP busy frequency detector;
Rick KN6KB prototyped it quickly, and was surprised by how well it
worked.
>>>Furthermore, Rick is a member of the WinLink Development team; he
could extend the existing WinLink PMBO implementation to include the
SCAMP busy frequency detector, were the WinLink organization
interested in reducing QRM. Worst case, the cost would be an
additional soundcard for each PMBO.
Also, there is reasonably founded suspicion by the Winlink team that
if they used such a thing, there are people willing to create a sort
of zombie network to cause intentional QRM to grind the Winlink
network to halt. Such an attitude against pactor and Winlink DOES
exist. Things could have been some other way if such a threat had not
been created.
>>>"We need to keep QRMing fellow operators because our QRM has made
them angry so if we stop they'll retaliate" is a recipe for
continuous escalation. A "zombie network" such as the one you
describe above would be either blatant and effective, or stealthy and
ineffective. In the first case, track it down and then shut it down;
in the second, ignore it and it will go away.
>snip<
What all of this should be is about getting someone capable enough to
come forward with a working solution available to all. So far, all
the previous preaching has proven unable to achieve so.
>>>There has been not one report of failure by any developer
attempting to build a busy frequency detector for use in unattended
stations. The one well-reported attempt to build a busy frequency
detector succeeded beyond expections, but inexplicably has not been
deployed.
Haven't we had enough of it already?
>>> I will stop debunking fallacious arguments when they cease to be
made -- or when someone demonstrates that they aren't fallacious.
73,
Dave, AA6YQ
