I was talking to a local emcomm coordinator who is very active and who I
consider an expert in the category - the question was about the use of file
transfer in a emergency communication situation.
He cited a couple of logical uses (spreadsheet file to hold personal roster,
or lists of available supplies, etc) which I could understand. He told me
normally this is done using VHF/UHF stuff now.
So I asked what sort of emergency would call for needing to use file
transfer on HF. He said if the disaster area covered multiple states and
was the sort where you could not get close enough to use UHF/VHF. What sort
of emergency scenario is that? A nuclear attack was the only answer he
could come up with. How would that work, I asked? He said the military has
a similar system and the area would almost certainly be under military
control and how the ham emcomm support would mix in would determine on the
nature of the event.
Now I don't know much about emcomm strategy myself, but I am pretty sure
that in the event of a nuclear attack, I could not envision how transferring
spreadsheets over HF would actually be a priority given the disruption in
every aspect of society.
So in the argument of what the file transfer need is, it's a lot easier to
comprehend a guy wanting to avoid the subscription costs of using a
commercial service and handle his email over HF needs. Than it is to say we
need this expanded bandwidth to handle a disaster scenario that is going to
be rare, and is going to have military priority, and would be so severe that
the utility of this feature would be on the back end of the emergency.
Maybe I'm missing the big picture. But it's not for lack of trying to
understand the emcomm-wide data need/benefit case, where the Winlink et. al.
users need is really easy to understand.
73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie
-----Original Message-----
From: Richard Thorne
Sent: Wednesday, August 24, 2016 9:27 AM
To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] RM11708 and the Future
If there aren't going to be that many pactor-4 signals on the air due to
the cost of modems, the signals should have a bandwidth limitation. In
addition there should be a band plan for pactor-4 signals by keeping
them above 100khz from the bottom of the band. I suspect that if
pactor-4 is allowed in the lower portion of the bands that the cost of
modems would come down.
Emergency communications, which are important and luckily don't happen
very often, could be handle above 100khz.
The experimentation idea doesn't hold water either. We know that
sending more data at faster speeds requires more bandwidth. How much
data needs to be sent during an emergency? Amateur frequencies are
intended for amateur use, not commercial use.
Twisting the big knob when a pactor-4 station comes on frequency,
without checking first, is not an option in my book.
That being said, if you don't agree with pactor-4 being allowed in the
cw/rtty sub-bands you better start writing the ARRL and making an
appropriate comment against RM-11708.
Rich - N5ZC
On 8/23/2016 3:43 PM, Ward Silver wrote:
First, I do agree with N9NB that there needs to be a bandwidth limit in
the amateur bands - this has been confirmed by the FCC in numerous
communications and opinions about overly-wide phone signals and also by
97.307(f)(1) which limits the modulation index of angle-modulated phone
emissions to less than 1 at the highest modulating frequency. Clearly,
the idea of a maximum bandwidth is considered good practice in the phone
sub-bands and a similar limit in the RTTY/data sub-bands does not need to
strangle technical innovation. Nevertheless, it is not sufficient to rely
on the "necessary" and "good practice" wording in 97.303(1) because
neither is strong enough to be meaningful without creating endless
arguments and perceived loopholes. So just place a reasonable "roofing
bandwidth" on amateur radio emissions below 30 MHz - 3 kHz? 6 kHz? 10
kHz? - and let us sort it out as we do every day!
[If the maximum bandwidths of phone and data signals are to be linked in
one rule, a simple administrative fix could be made by the very simple
change of applying 97.307(f)(2) to all of the HF bands - renumber it from
97.307(f)(2) to 97.307(g) or add (2) to all of the HF bands in 97.305.
Digital voice would remain confined to the phone bands because even though
it is transmitted as bits, the overall package is still classified as a
phone emission, just as digitized images are still considered image
emissions (facsimile). (See 97.3(c) and 2.201)]
Let's get a grip, though...in my opinion:
PACTOR 4 is already permitted everywhere else in the world and has not
ruined ham radio yet. PACTOR 3 and PACTOR 4 modems are expensive - the
rush to use >$1000 modems to exchange non-commercial traffic at <10 kbps
(at best less than 1/5th of dial-up rates) over HF is not a very strong
business case. While it is popular to gnash our collective teeth about
those impure "boaters," (Oh, the fiends, checking their stocks via amateur
radio!) the primary use of the Winlink system is rapidly shifting toward
emcomm/public service, which is prominent in our Basis and Purpose of
97.1(a). Using faster modems actually reduces band occupancy in terms of
Hz-sec for any particular message - although better performance *might*
increase the number of messages. But at <10 kbps and with the horrible
things that HF does to a channel...I just don't see a stampede
materializing.
More importantly, ham radio needs to get with the program - our
over-reliance on decades-old analog modes is laughable. You want new
technical blood to fulfill 97.1(d)? Try explaining to anyone under 40
that our primary HF digital modes run at 31 baud or use the 80-year-old
5-bit Baudot code developed for electromechanical printers and which can't
even handle the full alphanumeric character set. Inform them of our
300-baud symbol rate limit below 30 MHz and, after their initial
disbelief, you will get a look of pity followed by complete disinterest.
In most student papers at engineering conferences everything under 1 GHz
is considered BASEBAND AUDIO!
Nor is it a good idea to further splinter the ham bands - it just creates
unreasonable expectations of ownership or occupation. Many operators
discovered during the W1AW/portable year how channelized 40/75 meters had
effectively become, simply due to squatter's rights. We are always
pooh-poohing band plans during contest weekends - rightfully - and any
kind of reserved-for-narrowband allocation will simultaneously create the
expectation that narrowband signals stay within it. There is lots of room
on the bands for all kinds of signals if we could only get over the notion
of reserved sub-bands, calling frequencies, net lists, and
been-here-for-years. We have these Big Knob thingies we can use. We're
not rockbound any more. Frankly, I think the whole notion of band plans
needs to be greatly de-emphasized. We are the most flexible
telecommunication service of all - why are we so intent on throwing that
away?
Consider the use of "smart spectrum" SDR-based displays showing where all
the signals of various types are and aren't. (The RBN almost does that
now...) With so many different modes and more on the way, it seems to me
that approach is a better way of going forward in line with the "cognitive
radio" approach to spectrum management and our mandate in 97.1(b) and (c).
Alternatively, if the bands are going to be segregated, then do it
according to behavior (see my Contest Update editorials of Sep/Oct 2005)
which is the root cause of most inter-mode conflicts, anyway.
A real problem that has been identified by many, and which is something we
really *do* need to address for *all* modes, is transmitter linearity and
noise. We have fantastic receivers that can hear a skeeter fart but the
bands are full of our own trash from non-linear and noisy transmitters -
even the expensive ones. (That we are still dealing with key clicks in the
year 2016 is ridiculous.) There are plenty of techniques that we could
adapt from the wireless data industry, such as pre-distortion and
higher-voltage final transistors, all well-characterized mature
technologies. The linearity issues with complex I/Q data signals are the
same as for speech modulation. Let us solve noise and transmitter IMD and
it will be a lot easier for everybody to get along. Digital modes can be a
lot more noise-tolerant, too, and that might help a lot with the new
reality of all spectrum, just as FM was invented by Armstrong in response
to AM static.
Also...this CW...I turn on my radio most weekdays and wonder where is this
precious commodity we are trying to preserve? Sure - contest weekends
sure load up the bands - but the other 90%+ of the time the CW areas are
pretty empty. I love CW but I am not of the opinion that we have to
hobble the service and keep it increasingly technically irrelevant in
order to preserve a century-old mode that isn't the backbone of the
service it once was.
The sky is not going to fall. Yes, I will swear like a sailor when a data
signal wipes out my CW run frequency, but then I'll use my Big Knob and
start again somewhere else. (Or just stay there and duke it out.) Ham
radio needs to accommodate useful data modes if it is going to survive to
celebrate its second century.
73, Ward N0AX
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