[aprssig] Igate,APRS-IS, Messaging

[kb2scs at optonline.net]

Hi All

> Bob WB4APR wrote...

>  Thanks for the test, but your test did not test that function.
>  Yes, everything gets to FINDU.  But only messages go
>  back to RF if an IGate recognizes a local station AND
>  the SERVER that it is connected to recognizes the
>  station as within the range filter of that IGate.

Steve I know that you answered this already but I am still confused 
by the above statements.

Here is how I think that the message function of the APRS-IS works.
No matter what filter a connected station to the APRS-IS is using be 
it an Igate or just a client station all messages are passed to all 
connected stations. The sending station does not need a valid 
position. Acks are sent also to all connected stations even if the 
sending station does not have a valid position.

If the above statements are true then the aprs-scs Igate function 
will send out to rf messages to "local" stations. Local stations are 
determined by aprs-scs by there "hop" distance from the aprs-scs 
Igate. This hop distance is user configurable. 

Zero hops: only stations heard direct will get messages and acks sent 
to rf

One hop:   Direct stations and those one hop away will get messages 
and acks sent to rf.

Two hops: Direct stations, One hop stations and two hop stations will 
get messages and acks sent to rf.

Three hops: Direct stations, One hop stations, Two hop stations and 
those three hops away will get messages and acks sent to rf.

It was a lot of fun coding the WIDEn-N to figure out the number of 
hops used before reaching the aprs-scs Igate. 
  
Let us hope we never witness the "Silence Of The Hams"
73 DE John  KB2SCS
       E-Mail:            kb2scs at arrl.net
       APRS-SCS     http://www.tapr.org/~kb2scs
       Web Page:     http://www.qsl.net/kb2scs