[aprssig] Weather Alert Network on APRS

Robert Bruninga bruninga at usna.edu
Tue May 1 13:13:05 EDT 2007


> In Michigan, we ... use it for routing traffic
> -to- the NWS offices... we setup specific digis...
> as (L) digis ... and put WX inside the UIDIGI command.
> Then we have the ... weather stations send to
> WX2-2 or WX3-3 as needed to get them to the appropriate 
> counties, digis and Igates.  

Im confused.  If WX is in the UIDIGI list, then it is not an
"n-N" process, and users would need to use the path of WX,WX,WX
to go three hops.  Maybe you meant to say that WX is in the
UIFLOOD parameter.  Then WXn-N would be supported.

Although this use of WXn-N to get all WX packets in a given area
into the NWS is a great application, it seems to me to missing
one of the more valuable parts of the SSn-N system, and that is
uniqueness of area covered.

By using WXn-N, then there can be no other contiguous WXn-N
systems anyhwere in the surrounding areas.  I would think that
using a specific NWSXn-N for a given NWS to make the path unique
would gain the most advantage of the SSn-N system.  That is,
guaranteed coverage of the entire NWSXn-N area, and no
spill-over into adjacent NWSYn-N and NWSZn-N areas.?

Also, you lose the SSn-N for that state or region.  How many
hops are required? 

If only a small few stations need 3 hops and most of them can
get by with two hops, then WIDE1-1,NWSX would get to the NWSX
site if all of the digis that the NWSX site can hear all have
NWSX in their UIDIGI list.

Using an outgoing path of VIA WIDE2-2,NWSX would work for all WX
staions that are 3 hops from the NWS site.

> It has worked very well, but the problem becomes if you 
> have end-user weather stations and they send to a 
> standard path and not WX VIA WX2-2 then
> the NWS will not pick them up because of the script 
> we use to catch the WX in the TO call.

I am confused by this too.  Why does the script need to be so
exclusive to only capture packets using that special path?  I
woiuld think that the parser would accept ANY APRS weather
station, no matter what the path an dno matter how it got there.

> There has been pluses and minuses to doing it this way, 
> but overall it has allowed us to use VERY high beacon 
> rate on specific weather stations for the
> good of the 3 regional NWS offices.

I'd like to hear more about how this works, because there are a
lot of areas that might want to do similar things.  If you
require that all WX packets get to all 3 NWS offices, then maybe
you would want to use WXMn-N where "M" makes it unique to
Michigan (though if no one else nearby is using WX, then I guess
it is a moot point.

So, I'd be curious of the statistics.  That is, how many WX
stations need 3 hops, how many need 2, and how many need 1.
Does each WX station have to get to all 3 NWS sites or at least
just one? Etc...

Just curious
Bob

> I think that is an excellent use of the UIDIGI parameters.
Now
> that most areas are upgraded to the New-N paradigm, more of
the
> four UIDIGI settings are available for this use.  But to make
it
> work most efficiently,
> I would think that the originating Igate would want to make
sure
> the path does include multiple broadcast hops.  SO therefore
it
> should probably use a discrete path to the digi that is most
> central to the area, and then a single WXMHX beyond that as in
> DIGI1,WXMHX.  Would that work?
> 
> Because using multiple hop WXMHX,WXMHX hops has the same
> RELAY,WIDE dupe problem we are trying to avoid.  But proper
> choices can minimize QRM and maximize the coverage.  The
problem
> is the large number of set-and-forget digipeaters out there...
> 
> Bob, WB4APR
> 
> 
> 
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