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[aprssig] Why RELAY,WIDE... is so bad....

Wes Johnston aprs at kd4rdb.com
Fri Apr 1 15:53:30 UTC 2005


I've thought about this extensively this morning, and using a path of
WIDE1-1,WIDE2-2 works!

If a home station were to hear W1-1,W2-2 it'd come out as W1-1*,W2-2. 
The next home station would not respond to W2-2.  The local digi would
hear it and digipeat it out as W1-1*,W2-1.  Even if another copy of the
original packet came in from another home station, the local digi would
not digipeat it again.

I thought about what if we programmed the home stations to respond to
W2-2?  Well, that would be bad news.... a path such as W2-2,W2-2 would
come out as W2-2*,W2-2, and if another home station heard it, they would
digi it also... it'd come out the 2nd home station as W2-2*,W2-2*....
and if more than one home station heard it, we'd have mess on our
hands.... It'd be like running a path of R,R,R.

Obviously, if a digipeater heard W1-1,W2-2, it'd digipeat it as
W1-0*,W2-2, so it works properly in every case!

Now, if my packet with a path of W1-0*,W2-1  found it's way into the
next town, no home stations would digipeat this one b/c W2-1 is not in
their MYA or UIDIGI lists. 

I think that the recommended path for mobiles should become:
WIDE1-1,WIDE2-2
or
WIDE1-1,WIDE3-3

Of course the sets the minimum number of hops to 3.  The rule of thumb
would become never run WIDE1-1 after the first position.

Home stations would simply program their MYAlias to WIDE1-1, and would
only digipeat a packet if they heard it on the first hop (ie direct). 
This seems to be the best we can do with what we have on hand today.  I
can still utilize a home station's digipeating ability if I'm in a hole
and can't  hit the digi... the digi's still respond to the first hop if
I happen to hit them first, and the digi's won't dupe any packets.

The only problem I see is the time it'd take to spread the word to the
users to program their TNCs to WIDE1-1 instead of RELAY... perhaps in
the interim, another digipeatable alias would be used by the home
stations so they could respond to RELAY and W1-1.  Then we could sunset
the RELAY.  Also, not that anyone does this today anyway, but we have to
re-educate everyone to not run W1-1 after the first position.

Wes



Curt, WE7U wrote:

>On Thu, 31 Mar 2005, Stephen H. Smith wrote:
>  
>
>I could see going for that.  It means the home stations are mostly
>silent until they are needed, s most people will wide2-2 in there
>instead.  Just the mobiles/portables needing it will have wide1-1 in
>the first slot.
>
>This means that you can still get duplicate packets because of the
>home digi's, but the hilltop digi's will include it in their
>dupe-checking.
>
>Seems to work for what I need!
>
>--
>Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
>"Lotto:    A tax on people who are bad at math." -- unknown
>"Windows:  Microsoft's tax on computer illiterates." -- WE7U
>"The world DOES revolve around me:  I picked the coordinate system!"
>
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