-----Original Message-----
From: Dave AA6YQ [mailto:aa6yq@ambersoft.com]
Sent: Wednesday, April 06, 2005 1:36 PM
To: bandwidth@arrl.org; k1ki@arrl.org; k1zz@arrl.org
Subject: Pactor, Winlink, and semi-automatic operation on the HF bands: a
straightforward resolution
An unfortunate side-effect of the ARRL's proposed shift to "regulation by
bandwidth" is that semi-automatic operation would no longer be restricted to
specific sub-bands, as it is today; such operation would only be restricted
by signal bandwidth. Without question, semi-automatic operation QRMs ongoing
QSOs; the hidden-transmitter problem is well understood in theory and occurs
with non-trivial frequency in the semi-automatic sub-bands, all of which are
shared with operators wishing to QSO other operators. The QRM occurs because
most semi-automatic stations do not detect ongoing QSOs in modes other than
their own; if they detect an incoming request, they respond whether or not
the frequency is already in use. The hidden-transmitter scenario is
independent of mode or bandwidth, other than the fact that a semi-automatic
station using a wider bandwidth signal is more likely to QRM ongoing QSOs
than one using a more narrow signal.
The hidden-transmitter problem can be mitigated by equipping semi-automatic
stations with "busy detectors" for commonly-used modes like SSB, CW, RTTY,
PSK, MFSK, and SSTV. With appropriately-designed station automation
software, a semi-automatic station using a protocol with busy detectors
would rarely QRM an ongoing QSO. SCAMP, a new protocol being developed by
Rick KN6KB, includes such busy detectors; initial reports on the efficacy of
these busy detectors from SCAMP beta test users have been positive.
Therefore, I respectfully propose that the ARRL incorporate the following
policies into its "regulation by bandwidth" proposal:
1. Station automation application software is deemed "qualified" if it
demonstrably refrains from responding to an incoming request if such a
response would QRM an ongoing QSO in SSB, CW, RTTY, PSK, MFSK, or SSTV modes
-- unless overridden by an operator during a declared emergency.
2. Semi-automatic operation with unqualified station automatic software
remains restricted to today's defined sub-bands; one year from the adoption
of this proposal, the extent of these sub-bands should be significantly
reduced (but not eliminated).
3. Semi-automatic operation with qualified station automation is restricted
only by signal bandwidth, like any other amateur transmission under the new
bandwidth-based proposal.
These policies would gradually eliminate QRM from semi-automatic operation
by incentivizing a transition to qualified station automation software, by
encouraging the development of protocols with busy detectors, and ultimately
by shrinking the spectrum in which semi-automatic operation with unqualified
station automation software is permitted. They would foster the development
of better semi-automatic station automation software. Current users of
semi-automatic operation like Winlink could effectively migrate most of
their traffic to qualified semi-automatic operation while continuing to
support any users wishing to remain with protocols like Pactor.
73,
Dave Bernstein, AA6YQ
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