[MNAPRS] APRS UHF 446.175

[Matt Holden]

My desire to try APRS on UHF is to do something different.  I went to Tokyo
ham fair, last summer, and noticed Kenwood had their APRS radios set to UHF
9600 baud.  We've been on 144.39 for 20+ years. Let's get a bit innovative.
I think many people don't use the "other" band on their dual band radio and
might find this a way to get off two meters.
On two meters, I'm frustrated by all the fixed infrastructure that asks for
WIDE digipeats.  I set our KDØCL digi to none because I'm advertising our
local repeater and don't think people 30+ miles need to be bothered by our
packets because our repeater doesn't hear well beyond 15 miles anyway.  I
think the idea of setting nodes down to WIDE2-1 or NONE is a great idea.  A
lot of the APRS infrastructure has been set and forgotten about.  It will
take years before all node owners wake up to the new paradigm and take the
time to flash their old TNCs to replace WIDE2-2 (or higher number of hops)
with WIDE2-1 or NONE.
I think special events may be better served by having a separate APRS
frequency and why not have it on UHF?
I think one or two well placed UHF digis are all the twin cities needs.
W0YC proved that on VHF with the fine placement of W0YC-5.
On a side note, I'm excited to see Kenwood's new tri-band HT with
APRS/D-STAR built in.  It was announced at Dayton but no delivery date
sent.  Can you imagine APRS on 220MHz?
73 Matt KØBBC


On Fri, Jun 3, 2016 at 11:00 PM, Doug Reed <n0nas at amsat.org> wrote:

> Using a path of NONE or LOCAL would just make it explicit that you
> don't want the packet repeated by anyone. If it is heard by an I-gate
> it would probably still be gated, but that is about it. I prefer LOCAL
> over NONE, but I don't think there is an "approved" label for no path,
> so you can use anything that makes sense to you. And if you have a
> specific target station in mind, you can still use that station's
> callsign in the path to make sure only they repeat the packet.
>
> WIDE1-1 was the path originally intended for use by home stations or
> "fill digis". It used to be RELAY but got revised in the New Paradigm.
> It was intended to be programmed into home TNCs as an alias so the TNC
> would repeat the packet when it heard anything addressed to RELAY, or
> these days, addressed to WIDE1-1. This worked because even an ancient
> TNC that never heard of APRS would properly respond to its programmed
> MYALIAS. As a side benefit, a WIDEn-n digi should respond to WIDE1-1
> and give the packet one repeat.
>
> But it is preferred that you use WIDE2-1 if you only want WIDEs to
> repeat the packet since WIDE1-1 would hit those home or fill digis
> too. When I program a beacon for a WIDE digi, I use WIDE2-1 for the
> path if I want it repeated by the next ring or use LOCAL or NONE for
> infrastructure beacons that I don't want repeated outside the digis RF
> footprint.
>
> Then we get into WIDEn-n digis. They are the wide area digipeaters
> intended to provide coverage over a large area. It collects anything
> it hears addressed to WIDE and repeats it depending on the count after
> the dash. Originally it could go up to WIDE7-7 but that becomes
> completely untenable and with I-gates it is pretty unnecessary. These
> days WIDE3-n is reserved for areas that are WAY out in the boonies
> where it takes three hops to get to anyone. It is generally recognized
> and suggested that nobody use greater than two hops except in a
> special case. But it is still considered good for mobile and portable
> stations to use WIDE1-1, WIDE2-1 as a path for that slight added
> chance that you may be close enough to a home station and need its
> help to hit the local WIDE.
>
> The normal config for a WIDE includes an attempt to "kill" any packet
> that requests greater than n= 2 or 3 for a path. If the digi hears
> WIDE5-5, it will repeat the packet ONCE and terminate the path so it
> doesn't get repeated again. Some versions of software, such as the
> OpenTrack TNCs will terminate any packet with n greater than some
> value, so it will kill even the WIDE7-6 packets that other software
> will handle normally.
>
> The other path that was added with New Paradigm was the state-wide
> system based on MNn-n or whatever state abbreviation you want. The
> packet is handled like a WIDEn-n packet except it will not be repeated
> by a digi in the next state. This was intended to be for emergency or
> other special use but I've never seen it actually used. But it is in
> every digi I maintain.
>
> My rule-of-thumb is that a good WIDE will hear 30-50 miles if it has a
> good location. If it can't hear 30 miles, I don't think of it as a
> WIDE. I tend to look for locations 60-80 miles apart for the next
> WIDE. But that rule does break down when you get into hilly terrain
> such as Winona to La Crosse, or up toward Bemidji. It is very helpful
> to use aprs.fi to display "stations heard" on a map. I sometimes wish
> for such a map with overlapping coverage from other digis. It makes it
> easy to look at the map and figure out where the next hole is that
> needs filling. I particularly like to look at the maps and see the
> actual coverage from a site, including any offset for antenna pattern.
>
> The bit of the New Paradigm that might get overlooked is that we no
> longer want our APRS stations to be "polite". We don't want them to
> wait for clear air, we want every station that heard a new packet to
> retransmit that packet as soon as possible after it ends. No waiting,
> just transmit immediately with the intention being that everyone who
> heard the packet will transmit at the same time and walk on each
> other. The only people who will TX the packet a second time are the
> ones who didn't hear it the first time. If you ever hear a station
> retransmit the identical packet a second time, it is because there was
> an error in the software or it isn't programmed right..... The UITRACE
> function is supposed to prevent that....
>
> I recall two more special paths, RFONLY and IGATE. They do what they
> say. RFONLY would not be gated and IGATE would go to the Internet but
> not be digi'ed on RF. I suppose you could use IGATE as the path
> instead of LOCAL if that is what you intended.
>
> It has been a few years since I read the New Paradigm docs. I should
> probably go back and read the www.aprs.org web site again to see what
> else I've missed.... The APRStt and Voice Alert stuff was fairly new
> to me....
>
> Looking at the APRS world map, I note that Europe and Africa use
> 144.800 for APRS, just like we use 144.390. So the people out on the
> east coast trying to hold a 2M QSO from the US to Europe should
> probably monitor each others APRS frequency, just like we watch
> Mountain Lake for APRS propagation alerts.... I wonder if they do???
>
> 73, Doug Reed, N0NAS.
>



-- 
73,
Matt Holden KØBBC
ARRL Vice Director Dakota Division
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