[aprssig] This Year's Cross-Country Road Trip With HF APRS

Max Harper kg4pid at yahoo.com
Mon Aug 31 07:48:09 CDT 2015


Stephen, have you ever used Mike Berg's FreeTrak-16 to do the encoding?
http://www.ringolake.com/pic_proj/MFSK16/mfsk_main.html
I was curious if you had, and how well it worked. I have the PCB and most of the parts, but haven't put it all together yet.
I would also be interested in any links to the current loop antenna you are using.
Max KG4PID
       From: Stephen H. Smith via aprssig <aprssig at tapr.org>
 To: TAPR APRS Mailing List <aprssig at tapr.org> 
 Sent: Sunday, August 30, 2015 11:26 PM
 Subject: [aprssig] This Year's Cross-Country Road Trip With HF APRS
   
This year, as usual, I made the annual cross-country road trip from central 
Michigan to Los Angeles, Cal, with the obligatory stop in Colorado for the 
Evergreen Jazz Festival at the end of July.    Just before the trip, I 
upgraded my homebrew 30M magloop to a new third-generation design. I increased 
the loop circumference from 10' (3 meters) to 20' (6 meters; i.e. from a 
diameter of 3.2 feet (.93 meters) to 6.4 feet (1.9 meters) and changed the 
scheme for resonating the loop.

According to the KI6GD magloop calculator, I boosted the efficiency from about 
35% of a full-size dipole to 68%; i.e. barely 1 dB down from a dipole.  I set 
my home station Kenwood TS-50 to do the APRS Messenger dual-mode alternate 
beaconing on MFSK16 and AX.25 packet APRS before I left.  [The latest revision 
of APRS Messenger now makes it trivially simple to beacon alternately on the 
two modes using the UZ7HO Soundmodem for the packet side.]

This has been an absolutely lousy ratty solar max compared to the solar max 
around 2001-2004, where I routinely carried out perfect SSTV two-ways from the 
car to Japan, Australia, New Zealand & South America.  During the solar minimum 
4-6 years ago, I routinely carried out APRS Messenger PSK63 QSOs from the car 
to almost anywhere in the US 18 hours a day or more. I could make contacts from 
the mobile in downtown Los Angeles or Las Vegas to stations in Kentucky and 
Thunder Bay, Ontario pretty much any time I wanted.

This summer, the absolutely non-stop sequence  of solar explosions, coronal 
mass ejections, geo-magnetic disturbances, high solar "A" and "K" indices, and 
exceptionally flaky sun spot behavior combined to render this positively the 
worst summer I have ever experienced for HF mobile operation in over 25 years 
of making this trip.

Usually, I run mobile live SSTV (from the WA8LMF "Mobile SSTV LiveCAM" 
dash-mounted camera) on 20 and 15 meters on this summer trip, especially as I 
cross the scenic parts of Colorado and Utah.  In between SSTV sessions, I 
beacon constantly on 30M APRS with both the APRS Messenger MFSK16 mode, and on 
classic AX.25 packet APRS.  During the the 6300-mile (10,000 KM) trip, I copied 
exactly ONE SSTV image on 20 meters.

The 30M band sounded totally dead most of the time. I barely copied ANY AX.25 
APRS at all, -BUT- the MFSK16 mode in APRS Messenger was absolutely amazing. 
For the first 1000-1200 miles (1600-1900 KM) up to western Colorado, I was 
copying my 50-watt home station transmissions from the magloop 18-20 hours a 
day, even when the band otherwise sounded completely dead with no AX.25 signals 
whatsoever.

Even on the west coast in Los Angeles and the San Francisco Bay area, and in 
the interior of Nevada, I was copying my home station 8-12 hours a day most of 
the time, again on an otherwise completely dead band. This is a distance of 
around 2000 miles (3200 KM) under absolutely rotten propagation conditions. 
Repeated checks at WiFi hotspots from my mobile laptop confirmed that about 
half the packets from my mobile, that reached the Internet, were being igated 
by my own home station in Michigan.

Once again, this has demonstrated the incredible superiority of MFSK16 over 
conventional AX.25 packet on HF if you want to be seen from the remotest places.

___________________________________________________________________

--

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

Live Off-The-Air APRS Activity Maps
    <http://wa8lmf.net/map>

Long-Range APRS on 30 Meters HF
    <http://wa8lmf.net/aprs/HF_APRS_Notes.htm>

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