[aprssig] APRS on RF?

Wes Johnston aprs at kd4rdb.com
Wed Apr 13 12:31:52 EDT 2005

Jason, part of the problem is that hams by nature want to see DX. 
Worked All States means you contacted all 50 states at one time or
another, not that you can talk to any of the 50 _today_.  APRS for many
is just that... wow... I can see a station in OHIO.... wow.. I can see a
station in IDAHO.  When I first got into APRS, I must admit it was
something I enjoyed.  But then I came to realize that all those DX
stations coming in are in direct competition with my mobile's access to
a local digi.  Now we are faced with a choice... do you wanna see
occasional stations from far, far away, or do you want reliable
communications with the people right around you?   I want to see locals
reliably.  But people in other areas, want to either see stations from
the kingdom of Far Far Away, or want to be seen in Far Far Away (yes, I
have kids and we have watched Shrek one too many times).  Problem is,
any attempt at DX will be unreliable, and they don't realize that or
they are just plain happy with having unreliable access so they can say
"look what's on my screen".  To them, I say, "yes, that's cool... you
have idaho on your screen... but you missed the packet that showed that
right turn your SAR vehicle took".

This leads us to Pete's "non source routing".  His idea takes these
egotistical paths and UTS (user too stoopid) paths out of the picture.  
The non-source routing scheme places a hard limit on how far away a
station can be away and still get into your local network.  In a
nutshell it works like this:  You are heard direct or up to one hop away
by a digipeater.  That digipeater places it's callsign in your path with
a * beside it.  Neighboring digi's that are in your LAN see the packet
with the first digi's callsign with *, and digipeat it.  Your packet
will not be repeated if A)it is not heard directly by a digi, B)If it
didn't enter the LAN thru a known local digipeater.  Yes, there are some
exceptions in there, but they are beyong the scope of this email....
let's just say his system checks to see if you are local before it'll
digipeat you.  It's a system with hard limits.

In his system, a LAN is a group of digipeaters that "know" each other. 
Now, at first this system sounds like if you travel from one town to
another, you will either be digipeated in one town or the other.  That's
not neccessarily true...  Consider that you have a linear string of
digipeaters number 1 to 10 (for the sake of this email... but the
concept still works in a 2d network map). 


"local" is usually 2 hops... so digipeater #3 will digipeat packets that
enter the network from #1,#2,#4,#5.  On the other hand, digipeater #4
will digipeat stations that enter the network by way of digipeater
#2,#3,#5,#6.  If you look carefully, you'll see that we can create a lan
with overlap into neighboring lan's.  Now the owner of digipeater #10
can decide that he'll accept packets from digi's #3-#9 as local because
there isn't much traffic in his area.  So there is flexibility in this
system.  The digipeater owner in your town will decide what neighboring
digipeaters will be repeated.... he will define your Aloha area.  And if
a new digipeater goes up, he'll decide to digipeat it's packets or not.

Maybe I'm getting too far along in this email, but I'd like to go on and
say there are two things that bothered me about this NSR idea.... one
was what about people who don't want to cover an entire area?  Well,
from a practical perspective, home stations are the easiest to alter
outbound paths and no one ever does.  Mobiles are set and forgot today
for the most part.... Truckers want to run W4-4 and don't reduce their
paths in more conjested areas.... so I backed up on my objection b/c we
_could_ limit range today but noone does anyway.  At least with NSR, the
_network_ can decide what's local.  My other objection was that it
pretty much stops the "come as you are" part of aprs as far as
digipeaters go.  If you add a new digi to the system, you have to
coordinate it wth all the other local digis.  In regular day to day
operation, that is fine... it serves to prevent the ego maniacs from
putting up digis that aren't needed.  But in the case that a digi is
damaged in a storm and needs to be replaced... well you just give the
replacement digi the same callsign as the on that has failed.  Or
program all the digis to know the callsign of a spare digipeater, and
leave that digipeater inactive until it's needed.  So there are
solutions to both things I can think of.

I would love to see our network one day where we could say, fine run a
path of W7-7... and the network would tweak it down to what was
reasonable for that area... there are two ways to do it... a hop limit
on UIFLOOD or Pete's NSR method.  Digined can do either!


ke4nyv at hamhud.net wrote:

>I have to admit its very frustrating to have UI-View running for a few days to
>only find a handful of local (within about 75 miles) to show up.  Then I go
>check findu.com or aprsworld.net and find the online stations are more than
>double.  I simply just ask myself "What the hell??"  This is a hobby of RADIO.
>Don't get me wrong, I love APRS-IS and all that its purpose serves.  But when
>I'm riding around watching my HamHUD or you D700 guys are doing the same, I
>want to see some local activity.  Our network is flooded with traffic, but the
>traffic comes in from other areas 80% of the time.
>This is has been a gripe of mine for several years now.  I understand that for
>the longest time it DID cost some to get a station on the air...mainly the TNC
>(about $180 new or $50 used).  But now there are so many options.  Number one
>being John Hansen's TNC-X KISS TNC: $45 for the basic kit or $70 with the USB
>module.  If APRS is your main goal, KISS is really all you need, how can you go
>wrong?  There is also the soundcard method.  Personally, I have not had great
>luck with it, but its a cheap option and real easy to setup with a couple of
>cables and a simple keying circuit.
>Anways, just my $0.02
>Jason KE4NYV
>RPC Electronics
>Quoting Robert Bruninga <bruninga at usna.edu>:
>>Saw this on the UIview reflector:
>>>... I am new to APRS and trying to learn.  I have the only
>>>APRS WX station on RADIO in my area, everyone else
>>>is on internet...
>>Actualy since APRS is 13 years old now,  I thought
>>that we would be able to do more with APRS in local
>>events.  But although the number of people that do APRS has
>>increased slightly from a few %, the number that can
>>actually use it in the field on RF may have dwindled.
>>These small numbers especially among the dedicated few
>>volunteers that do the bulk of special event operating,
>>make it difficult to use APRS for anything but a side-show
>>in many practical events...
>>Ham Radio.... don't forget the radio...
>>and take it outside... (its wireless)...
>>de Wb4APR
>>aprssig mailing list
>>aprssig at lists.tapr.org
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>aprssig at lists.tapr.org

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