[CQ-Contest] RM11708 and the Future

[Ward Silver]

Here some facts to consider and then I'll get busy with my comments to 
the NPRM:

Any mode that uses AFSK modulation of an SSB radio will be no wider than 
3 kHz, obviously.  If the radio could be modified with wider filters, 
the signals could get wider, too, but the phase/amplitude 
characteristics of the transmit chain needs to have much cleaner 
characteristics than for voice. (Direct FSK has different limiting 
issues.)  It would take a whole new modulation/transmission scheme to do 
wider-band data and that would demand an SDR with very low IMD in the 
amplifier chain.  The SDR part is straightforward since that's mostly 
math and FPGA programming.  The RF amplifier part is not so easy and 
will require advanced techniques from the wireless data industry such as 
adaptive pre-distortion.  (One benefit to SSB/CW operation from such an 
adaptation would be cleaner transmitters.)

We should take some comfort in the fact that there aren't many wideband 
data signals on shortwave commercial or military channels.  If wideband 
data was easy, they would be doing it now. They are not.  Here is an 
extensive table of characteristics for many known HF data modes, 
including military and commercial signals: 
http://www.sigidwiki.com/wiki/Category:HF

The widest signal in the table that is not a radar or a jammer is DRM 
(Digital Radio Mondiale) at 20 kHz and that's a "phone" signal for hi-fi 
audio.  The data version of DRM is much narrower and has been used on 
the ham bands for SSTV in the image sub-bands.  The widest pure data 
signal in the table has a 6 kHz bandwidth.  We might be concerned about 
the authorization of spread spectrum and wideband OFDM techniques but 
neither of those are authorized emissions below 30 MHz.  So...even if 
the FCC declines to put a bandwidth limit of 6 or even 10 kHz on amateur 
signals, we're not going to see a big influx of roaring, high-speed data 
anywhere on HF.  The physics of propagation just doesn't work and it 
takes a lot of engineering and equipment to make even the narrower modes 
perform.  I think they ought to keep a bandwidth limit because the HF 
bands are a shared resource but that's a behavioral concern.

= = =

What kind of a need is there for regional HF digital in emcomm? Well, 
earthquakes and hurricanes, for starters.  The Pacific NW just had their 
big tsunami/earthquake drill (The Great ShakeOut) and having lived there 
for a long time I can tell you it is not wild speculation that comms 
could be taken out for several million people in three states over 
several hundred miles along the I-5 corridor between Grants Pass, OR and 
Vancouver, BC.  VHF/UHF ain't gonna get 'er done.  The emergency groups 
up there are prepared to use HF (either Winlink systems or NBEMS) to 
coordinate on a state-wide basis.  Drill traffic is often passed over 
HF, sometimes through mailboxes hundreds or thousands of miles from the 
area due to the skip zone.

We have enjoyed a ten-year hiatus in big hurricanes hitting the 
southeast U.S. but HF is a prime resource for recovery from really big 
storms.  Here in Missouri, we have localized disasters (mostly) but 
there is no state-wide VHF+ system to support communications with the 
state Office of Emergency Services.  So the need is real.

= = =

The concern about session-based protocols (including AX.25) being hard 
to monitor is certainly valid.  PACTOR modes do support the ability to 
monitor the packets (with another PACTOR modem) for station ID.  The 
data is usually compressed, so unless you capture everything perfectly, 
you won't be able to tell what is being sent.  (I can't decipher 
cyrillic or katakana morse, either...) Here's a possible solution - 
create an network of PACTOR modems that listen to the various signals in 
monitor mode and post the station IDs and any other associated data 
online like the RBN system.  A "mode deciphering monitor" program that 
runs on one's personal SDR would be a worthy project, too.  Simple 
matter of programming :-)

The "hidden transmitter" problem is always a concern, even on CW/RTTY 
where a station who can't hear me tries to communicate with a station I 
can hear.  Yes, the channel-busy detectors could be better, but the 
operators have to engage.  This is why I lobbied (successfully) for a 
set of new questions in the General Class pool that directly address the 
requirements of a control operator to listen before initiating contact 
with a remote-control station.  Will they do it?  Some will and some 
won't, but at least they've had to learn about the requirement.

I've been clobbered by phone, RTTY, SSTV, and even CW signals from 
stations who could clearly hear my signal and just didn't care.  What 
did a famous phone contester once say, "A clear frequency is where the 
needle comes off the right-hand peg a little bit."  Data stations aren't 
the only offenders in this regard.

= = =

There is some historical precedent as to the benefits of loosening 
restrictions on amateur data experimentation.  The FCC NPRMs in the late 
1970s and early 1990s liberalizing amateur data modes resulted in a huge 
explosion of amateur innovation such as packet radio, various TOR modes, 
and other interesting developments.  This is generally viewed as a good 
thing.  Your cell phone, by the way, probably includes at a deep level 
some data protocols developed for amateur radio that were adapted for 
commercial use. (This is described in "A History of QST, Volume 1 - 
Technology," published in 2014.)  We have mostly forgotten what "data" 
was like (non-existent) in the days before hams could use ASCII.

= = =

Opening up bandwidths is just not going to be the calamity some of us 
are concerned about.  There will be some irritation (including mine) as 
we adjust to new patterns of band use (and the kids will play on our 
lawns) but I am willing to accept the risk, support innovation that 
responds to new needs, use my big knob, and move on.

73, Ward N0AX