Prior to the start of the demonstration, at the monitoring station,
we observed an existing SSB conversation going on just slightly off
the frequency and a CW station calling CQ on the frequency. After the
demonstration was complete the SSB station was still there but the CW
station was gone.
This is a prime example of the asymmetric nature of interference from
wide band modes to narrow band modes. It is *exactly* the reason the
FCC has, for approximately 80 years, protected narrow band modes in
between 30 and 50% of each HF amateur band from interference by wide
band modes.
The Commission restated and reaffirmed that policy when ARRL requested
that *wide band* image transmissions be included as data. In WT Order
04-104 (FCC 06-149) in 2006, the Commission clearly rebuked ARRL:
we note that eliminating or relaxing the bandwidth limitation would
de facto eliminate the separation of narrow bandwidth and wide
bandwidth emissions. We believe that separation of emission types by
bandwidth is accepted in the amateur service as a reasonable means to
minimize interference on shared frequencies and bands and, therefore,
we will not replace the 500 Hz bandwidth limitation with a 3 kHz
bandwidth limitation.
In footnote 89 of the same order the Commission expanded on the reasons
for the separation of wide bandwidth modes from narrow bandwidth modes:
Separation of emission types by bandwidth minimizes or reduces
interference because it protects narrow signals from interference
from wide signals. Amateur licensees have accepted this division of
spectrum as a method for minimizing interference for as long as the
amateur service has been regulated, and no commenter in this
proceeding requests eliminating emission segmentation based on
bandwidth.
The entire Report and Order in WT 04-104 (FCC 06-149) is here:
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-06-149A1.pdf
Based on the Commission's policy since the 1930's, ARRL *should have*
simply requested that RTTY and data be added to the list of wide band
emissions permitted with Phone and image, subject to the bandwidth
limits in 97.307(f)(2):
(2) No non-phone emission shall exceed the bandwidth of a
communications quality phone emission of the same modulation type.
The total bandwidth of an independent sideband emission (having B as
the first symbol), or a multiplexed image and phone emission, shall
not exceed that of a communications quality A3E emission.
Then the "loophole" that K1ZZ and KE4PT are so concerned about (multi-
carrier digital systems with symbol rates less than 300 baud) could be
precluded in the "narrow band" segments simply by amending 97.307(f)(3)
to specifically include a 500 Hz bandwidth limit without precluding
any experimentation, development, or deployment of new codes and
PACTOR 3/4 would be free to compete with other wideband modes.
Note that "regulation by bandwidth" which K1ZZ disingenuously claims
would be a new regulatory paradigm has, in the mind of the FCC, been
a fact of life for 80 years.
73,
... Joe, W4TV
On 3/21/2014 11:27 AM, Terry wrote:
Yesterday a few of us witnessed a demonstration of Winlink using the PACTOR
3 waveform. A simple one line email was sent from a EOC center in North
Texas to one of the Winlink stations in Central Texas around 6:00 PM CST.
The demonstration was monitored at a station in-between. The demonstration
was done on 40 meters just above 7.100 MHz. Prior to the start of the
demonstration, at the monitoring station, we observed an existing SSB
conversation going on just slightly off the frequency and a CW station
calling CQ on the frequency. After the demonstration was complete the
SSB station was still there but the CW station was gone. The transfer was
not timed but it was quick (probably two minutes) .
So I want to retract my earlier comments about Winlink being slow. The
demonstrated QRMing is a concern.
Thanks,
Terry
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