[aprssig] HF APRS igates on fldigi

[Stephen H. Smith]

On 5/9/2020 11:14 AM, Robert Bruninga wrote:
> On HF, and using the decaying algorithm, I'd start at 1m, 2m, 4m, 8m and then 
> stay at 16 minutes.  

Maybe this would work on other HF bands, BUT NOT ON 60M !!!

We CANNOT legally have any kind of automated "untouched-by-human-hands" 
spontaneous transmission on 60 meters.

The 60-meters "channels" (we are assigned only 5 single spot frequencies; not a 
band with lower and upper frequency limits) are shared with federal users like 
DOD and FEMA, with hams as secondary users.
     We are obligated to monitor before transmitting and immediately yield to 
federal users, should they activate a channel. Ham BBSes and mail-box-type 
automated systems are already explicitly prohibited on 60m.

Any APRS activity on 60M MUST be by single beacon-on-demand.

----------------

I've been thinking about APRS on 60 meters for some time now. 60M has some 
interesting attributes.
    There is no arbitrary segregation between voice and non-voice modes as on 
other HF bands. This means one can mix APRS and voice activities on the same 
channel.  Among other things, this makes practical Mic-E-style position bursts 
tailgating voice transmissions.
     NVIS (Near Virtical Incidence Skywave) propagation is excellent while 
mobile antennas are are substantially LESS horribly inefficient than on 75 
meters.  Because everyone is bound to specific spot channels, random call-ups, 
beaconing-in-the-blind, and net operations are more like 2M FM channels than 
the endless slightly-off-frequency "chasing" one often gets on HF/SSB on other 
bands.

Because of it's NVIS propagation, I think 60M has real potential for APRS 
operation in mountainous terrain.  2-meters often has no coverage at all, while 
the higher HF bands (like 30M) have sizable skip zones that make it impossible 
to hear anyone LESS than 250-300 miles away. 60 meters with it's 
high-angle-of-incidence skywave can "leap tall mountain ranges in a single 
bound".

Think, for example, Denver, CO to Granby. CO (southern entrance of Rocky 
Mountain National Park). They are only 55 miles apart but on opposite sides of
the Front Range of the Rockies towering 8-10 thousand feet higher than either 
end-point. 2 meters can't do this -  no line of sight.  30M HF can't do this - 
path is in it's skip zone. 75 might do this, but only at certain hours (and 
mobile antennas are big and horribly inefficient).  60M should be able to do 
this almost anytime on 60.

For the last several years I have been experimenting with 60 meters APRS during 
my annual trek each July to the Evergreen Colorado Jazz Festival, from my home 
in central Michigan.  I use a Yaesu FT-857 with an autotune "screwdriver" 
antenna.
     This trip is about a 1000-miles-long straight shot west down I-80 and 
I-76.  I leave two home stations running on receive-only igating to the APRS-IS 
on both 60 and 30 meters. I periodically beacon on both bands from the car 
en-route. I can check after each beacon with a smartphone to see if my home 
stations "heard it".
     The first day out from East Lansing, MI to Des Moines, IA has demonstrated 
continuous receive over the 0-450 mile or so range on 60. On 30M, my house 
doesn't start hearing me until I am somewhere west of Chicago (about 250 miles 
from home).
     Evergreen, CO is only about 30 miles from Denver as the crow flies, but 
down in a deep hole in the Front Range, at about 7,000 feet elevation, with 
mountains towering to 8000-8500 feet all around. In the early evening hours, I 
have actually been able to get a few random posits out of this hole to my home 
in Michigan on 60M. 30M does nothing. The higher HF bands like 30M don't work 
for this, because the very high launch angles required to get out of the hole 
don't reflect back to earth on the higher bands most of the time.

______________________________________________________________________

Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net

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