There are straightforward ways to successfully deal with this
scenario a large percentage of the time. After noting the transition
of a previously-busy frequency to not busy, an automatic station
would wait some period of time - say 3 minutes. If the frequency
remained clear during that interval, the automatic station would
send QRL? in CW. If the frequency remained clear for 15 seconds, the
automatic station would send QRL? in CW again. If the frequency
remained clear for another 15 seconds, the automatic station could
initiate transmission, or accept activation from remote stations.
In effect, an automatic station would be constantly monitoring its
frequency in order to know whether or not transmission is
acceptable. This protocol would not be foolproof -- doubling, or
assymetric propagation will certainly cause trouble. But if the
automatic protocol performs at least as well as a considerate human
operator in the same circumstances, then we should be satisfied.
Think of it as a Turing test for automatic stations...
73,
Dave, AA6YQ
--- In [email protected], "jgorman01" <[EMAIL PROTECTED]> wrote:
>
> Actually, busy detection, regardless of its efficacy has a
problem. I
> pointed this out in my comments to the FCC on RM-11306.
>
> If the originating station 'hears' a station it won't transmit.
But
> what happens when the station turns it over to the other party that
> the originating station can't hear. Does it immediately begin
> transmitting, wait one minute, two minutes, etc. It may very well
> time out and begin transmitting thus interfering with an ongoing
> conversation.
>
> To be sure of not interfering, both the originating (manual or
> automatic) and the automatic station must communicate in some
fashion
> to insure that IF either station hears a signal, neither sends.
>
> Jim
> WA0LYK
>
> --- In [email protected], "Dave Bernstein" <aa6yq@>
wrote:
> >
> > Yes, SCAMP's busy detectors exceeded everyone's expectations.
> >
> > Some SCS modems also include a busy frequency detector, but to
my
> > knowledge no automatic station operation software exploits them.
> >
> > The issue, as illustrated in John's scenario, is that the remote
> > station activating the automatic station has no idea what can be
> > heard on the frequency at the automatic station's QTH when the
two
> > are separated by any significant distance. Thus the remote
operator
> > cannot know that the frequency is truly clear without help from
a
> > person or circuit at the automatic station's QTH.
> >
> > 73,
> >
> > Dave, AA6YQ
> >
> >
> >
> > --- In [email protected], doc <kd4e@> wrote:
> > >
> > > Hasn't SCAMP already successfully demonstrated the technology
> > > for checking multiple modes prior to transmission?
> > >
> > > Also, just because one cannot detect 1/2 of a QSO does
> > > not mean that one may not detect the other 1/2.
> > >
> > > If one truly cannot detect either side (with reasonable
> > > receive sensitivity and antenna gain employed) then one's
> > > legal transmission (only the minimum power necessary to
> > > establish and maintain communications) will not be capable
> > > of QRMing the existing QSO.
> > >
> > > If you cannot hear them they should not be able to hear
> > > you -- unless you are running an "alligator" station
> > > (transmit side not balanced with the receive side).
> > >
> > > IMHO, YMMV ... 73, doc kd4e
> > >
> > > > Lets try the guy 150 miles from you well within your
> > > > ring of silence (you can't copy each other if you had to)
> > > > listens to the frenquncy (unable to ask if the frequency
> > > > is in use on every mode known to man) hears nothing.
> > > > brings up the auto station and in doing so QRM's a QSO
> > > > on the same frequency that he did not hear.
> > > >
> > > > Now as I see it that is not the fault of the auto station.
> > > > But I know you are going to say that the auto station
> > > > *should* be able to tell if it was in use. And that is
getting
> > > > real old with me.
> > >
> >
>
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