[MNham] APRS expansion plans

[Doug Reed]

At 12:19 AM 2/2/2004 -0600, Matt Werner wrote:
>I had a conversation with Jerry, N0MR the other day.  Jerry told me that
>there is a group of people in the Twin Cities area that may be interested in
>getting some APRS digipeters up in the arrowhead region of the state.
>I'm interested in more details that anyone would care to share.  I think it
>would be wise if we worked together on placing digis up here as we (local
>hams) are also working on a few projects such as the Silver Bay area and
>possibly Hibbing.  Coordination of our efforts would be wise.

Hi Matt.

Jerry was speaking of the TwinsLAN Digital ARC and me primarily. He
mentioned your name in an email last week and I forgot to follow up. 

I've been interested in APRS and packet for a long while. The push that
finally did some good came from Wayne KK6BT about 2.5 years ago. He
provided a TNC, power supply and antenna to put a WIDE on the air. TwinsLAN
arranged access to the Moundsview water tower (near Radio City) through
contacts with the Anoka Radio Club. And Metro Skywarn provided radios and
was the "lead" agency in the group to accept 501.C3 donations for the
project. I put the pieces together and we put N0NAS-10 on the air about
November 2001. A few months later another good site (285') was made
available so I assembled KK6BT-10. And last summer, NY9D and K0LAV made
space available on their site (125') in Little Falls so N0NAS-11 went on
the air. 

Plans for this spring and summer include installing a WIDE on top of Knapp
Hill in western Wisconsin, probably in Spring Valley (40'), possibly later
at a better site (160') in Emerald WI. Another site (130') in Rush City has
become available and that will help fill the hole between the metro and
Duluth. (I'd really prefer a high site in the Pine City-Hinckley-Mora area
instead.) And the third likely site (150') is Pequot Lakes up north of
Brainerd. Looking at a map, Aitkin looks like the best choice but I've had
no contacts from there about a possible site. And I'm trying to convince a
ham down south in Fairmont that a WIDE digi is a good thing to have in his
area...... 

If you plotted all the active WIDEs on a state map, you will see heavy
concentrations in the SE corner and up around Duluth. I'm working on the
basis of 60-80 miles between WIDEs with very good sites. At least down here
in the "flat" lands. On that basis, Aitkin is centered in the hole between
the WIDE at Little Falls, N0WW-10 in Deer River and the four WIDEs in and
around Duluth. But I'll take Pequot Lakes instead of Aitkin since I have a
site to use. If someone in Aitkin wants to volunteer an excellent water
tower or radio tower site, I'll take it.......

My map shows WIDE holes that need to be filled in the Hibbing-Virginia
area, another around Ely, and another around Taconite Harbor. But this was
simply based on spacing on the map. I haven't done any terrain based checks
to see what the real world does to my proposed spacing. I've got a copy of
Radio Mobile and the terrain data base for the 5 state area but haven't had
time to learn how to best use the program. But Radio Mobile (FREE!) is the
tool I want to use for the project. 

My choice of 60-80 miles between WIDEs is to minimize the number of sites I
have to build. But even at 60-80 miles, a good WIDE on a high site should
have no trouble hearing the other WIDEs in its area so beacons will be
passed. And a home station should be able to hear all the WIDEs in its area
with even a modest antenna. All you need to do is try listening to
repeaters outside your local area. If you can reliably hear a repeater 80
miles away, you'd be able to hear a WIDE at the same distance. 

And this certainly gives the users and clubs in between the WIDEs something
to do. They need to build RELAY stations to digi the local mobile beacons
up to the WIDE. The whole premise of APRS is that every home station should
be a RELAY to fill in holes in WIDE coverage. Unless you're at the bottom
of a gully with an antenna in the basement, a home RELAY should provide
enhanced coverage for mobiles in the vicinity out to 10 miles, maybe more.  

Having a high density of WIDE stations and local RELAYs brings up the
problem of "packet storms" when each beacon is repeated multiple times by
the RELAY and WIDE stations in the vicinity. I don't understand how you can
avoid them in Duluth since you seem to have four WIDEs within spitting
distance of each other. Why so many? Why not pick the best one and make the
rest RELAYs?

My best solution for the RELAY/WIDE problem is to have call sign
substitution turned OFF on every RELAY station. That means they need to do
10 minute ID beacons but every packet they digi will have the digi call
sign of RELAY. Even if the WIDE hears five RELAYed packets, it will only
send it once because the call sign RELAY is the same. But if the RELAY
station does call sign substitution, then the WIDE will hear five different
packets and transmit it five times. That is not good. 

On the WIDE/WIDE packet storm problem, the best option is to have the
UIDIGI option NOID set. Since this also leaves a "trail" showing where the
packet came from, this is a good thing for APRS. If the WIDE puts its own
call sign in the "digi'ed by" list, it will not repeat that packet when
heard again. That is about the best we can do with the APRS protocol as it
is. 

One last problem we have with wide spaced WIDEs is the need to run UIDIGI
RELAY,WIDE on each of them. Until there are enough local RELAY stations to
fill the holes, you need to have RELAY turned on in the UIDIGI options so
that when a mobile goes past beaconing RELAY,WIDE, the WIDE will repeat the
beacon as the first RELAY station. Until there are enough local RELAY
stations to support the WIDE, this is just a problem we have to live with.
As soon as there are a decent number of RELAY stations, you turn RELAY off
in the WIDE digi.... (Was this paragraph confusing enough with all the
RELAY and WIDES in it?)  

Since the MNAPRS web site is down, I've created a MNAPRS mailing list on
the TwinsLAN server. So far there isn't much activity but I'm hoping that
people with an interest in APRS will join the list. General information
about the mailing list and subscribing is at:
	http://lists.twinslan.org/twinslan/listinfo/mnaprs

I'd like to move the content from the MNAPRS web site to the TwinsLAN
server too, but I haven't been able to contact Wayne about it...... And I
believe I'm going to delete the old WX-APRS email list and move all the
subscribers to MNAPRS since WX-APRS is getting hit badly by the spammers
and I'd like to stop getting the reminders..... 

Regarding equipment for building a WIDE, I've been using 40 watt Mitrek
radios. They are easy to tune, stable, easy to mod, and most have been
quite reliable. I have had trouble at KK6BT-10 but there is now a spare
radio in place. I have a few more Mitrek radios and crystals, after that it
will be GE Phoenix, Delta, and Rangr radios. I'm learning to program and
retune them and they seem like nice radios. 

The KPC-3 TNCs with version 8.2 ROM or later are a good choice for TNC.
I'll be using TNC-2 clones in the future with new EPROM software called
UIDIGI by IW3FQG. The UIDIGI software allows me to dedicate the TNC to APRS
with the latest APRS features without having to buy new software from the
manufacturer. 

Coming up with power supplies, antennas, and coax is more of a problem than
the radio, TNC, and cabinet. And of course finding an excellent site is
also a problem...... I'm inclined to provide help with equipment if you
need it to get packet or APRS on the air in your area. It is my "build it
and they will come" theory. That is also why I'm running the Packet & Radio
Workshops during the winter months, the next of which is Saturday Feb 7 at
the Ramsey County EOC in Shoreview.... 

Metro Skywarn is still behind this project since the APRS WIDE digi network
can also digi weather beacons from private weather stations around the
state in to the National Weather Service data collection system. That means
donations to Metro Skywarn for APRS can be tax deductible. The next step is
to convince your local Emergency Manager or club to buy a Peet Brothers
weather station and put it on a local APRS station. The NWS wants
information from more than just its own sensors..... More info on the
Citizen Weather Observation Program is at:
	http://www.wxqa.com/

This has been another long email but I hope it will spark some discussion
on the MNham and MNAPRS email lists. What is happening in your area of the
state????

73, Doug Reed, N0NAS. 
Metro Skywarn, Inc.
TwinsLAN Digital ARC
Ramsey County Emergency Services