IMHO, there are only two ways of preventing HF data mode QRM other than the "hidden tranmitter"...
One is to have a universal mode decoder that would identify the mode or require that each mode send a common protocol at the beginning of each transmission to identify the mode and to have established sub-bands automatic/semi-automatic operation.
The second is to break up a large sub-band into channels and have each mode assigned a number of channels (all who want this raise their hand).
I suppose the their way would be would be to only allow "accepted" modes in one sub-band and agree to negotiate and QRM and all other modes in another sub-band where you must accept any and all QRM.
There maybe other ways, but its the way I see things now.
Walt/K5YFW
-----Original Message-----
From: digitalradio@yahoogroups.com
[mailto:digitalradio@yahoogroups.com]On Behalf Of Tim Gorman
Sent: Tuesday, February 21, 2006 4:51 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] Re: NTS and traffic handling and digital
Rick,
I think the problem is more complex than this. I believe you will find that
sub-bands will ALWAYS be the answer of choice.
First, I use a pk-232mbx on pactor in the automatic sub-bands as part of the
NTS-D system. This box only listens for other pactor stations. If I were to
be told that this was going to be banned from the ham bands, I would drop out
of the NTS-D. So would others who use exactly the same equipment. None of us
would have $1000 or more to get equipped with SCS modems. It would be much
better to keep these operations in the sub-bands and keep them operating than
to just kill the system by default.
Second, I would be interested in how SCAMP operated when QRM came on the
frequency? Did it end the session so it wouldn't QRM the other guy? Or was
the busy detector disabled after the session had been established?
If the later, the busy detection scheme is only a placebo for many, many
situations and not a true fix. Since the systems today offer no true trunk
system control signals (i.e. calls to a busy channel are not abandoned by the
originating end but just continue to be attempted) as soon as the automatic
station detects a clear channel (the station it could hear turns the
transmission over to a station that can't be heard) the session will be
started and will cause QRM. Bottom line? No difference. The QRM is just
delayed by one transmission period.
The only situations which would be truly helped would be those where the
automatic station can hear ALL stations in the QSO on the frequency of use.
If SCAMP stops operation upon busy detection, even after a session is
established, it is likely that the system would come to a screeching halt
during busy times of the day. Since it is likely this is when long distance
propagation may be at its best, system throughput could be drastically
impacted.
It would appear that the *only* way to minimize impacts of the automatic
stations is to maintain automatic subbands. Other operations who want to
venture into these areas should understand that protections against QRM are
not what they are in other areas.
For those who think that restricting automatic operations to small subbands is
not fair to operations like Winlink, I would be happy to lay out changes in
operation that would let Winlink pass all of its traffic on five 500hz
channels. That's not five channels per band but five total, and Pactor II at
that.
To those discussing email content. It is my opinion, for whatever that is
worth, that it is *not* the content of a specific communication that is the
problem, per se, but the *regularity* of third party communications. Regular
communications with third parties are specifically mentioned in the Part 97
rules. It would seem to be axiomatic that for one time use or even
non-regular use, almost any content could be allowed, even it is not what
most would consider acceptable. When the use is for third-party
communications on a regular basis, especially the *same* third party all the
time, the use enters a different realm.
For instance, I keep getting the issue of weather reports thrown out when the
subject comes up. These are *important* to ships at sea.
Well, what would happen if I started broadcasting the local NWS system on
3920khz or 146.52Mhz during times of bad weather? Wouldn't those weather
reports be important to people on the road during periods of snow and
freezing weather? If I were to do this on a regular basis, e.g. 24/7, does
anyone on here think it would take more than a few days for me to get a
letter from Riley?
Would the Winlink people support having this type of operation on the ham
bands?
Just as there are other radio services providing this service (i.e. the NWS),
there are other radio services providing for regular, third party email from
ships, yachts, and boats, be they on land or sea.
tim ab0wr
On Monday 20 February 2006 22:14, KV9U wrote:
> John,
>
> At one time it was not technically possible for a robot station on semi
> (or for that matter on fully) automatic, to be able to detect diverse
> signals in the pass band.
>
> There were some who said it could not be done. Well, it HAS been done.
> Do you understand this?
>
> Your acceptance of this kind of QRM is no longer acceptable to
> reasonable amateur radio operators who now know that there is this new
> technology developed by Rick, KN6KB, the current Winlink 2000
> programmer. I have personally tested it when he incorporated it into the
> SCAMP mode and it is superb.
>
> Most of us now expect (perhaps demand) that further development with
> automated digital modes and equipment will include the ability to hold
> off transmitting until the channel is clear. If this doesn't happen then
> the best that can be said is that these operations would have to be kept
> in small subbands, similar to the current fully automatic subbands (that
> also include the wide band semi-automatic operations).
>
> My preference, and I think you will find the preference of an increasing
> number of hams, is that any automatic operation that has no auto detect
> for a busy channel should be banned from the amateur radio bands.
>
> That is a very reasonable position to take considering the available
> software technology.
>
> 73,
>
> Rick, KV9U
>
> John Becker wrote:
> > 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.
>
> Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
>
> Other areas of interest:
>
> The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/
> DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy
> discussion)
>
>
> Yahoo! Groups Links
>
>
>
Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org
Other areas of interest:
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DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion)
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