Order Tray | Contact Us | Home | SIG Lists

[aprssig] Using digi_ned as a WIDE1-1 fill-in digi

Robert Bruninga bruninga at usna.edu
Mon Feb 9 17:31:56 UTC 2009


> I'm... bringing digi_ned online as a WIDE1-1
> 
> !3616.98N108222.54W#W1-1 K1LNX WIDE1-1 Digi

Please include a PHG string so that others can see the Power,
Height and antenna gain and the approximate coverage area.  

But you are correct, that there is not much value added by the
rest of the text.  K1LNX is already in the packet as the AX.25
callsign.  We already know it's a digi.  The W1 shows it is a
WIDE1-1.  So you really have plenty of room for other stuff.
Sometimes an email contact point is useful.  Also, hopefully you
might include an additional beacon for the recommended voice
repeater in the area, its net times and meeting dates, etc.
Please see www.aprs.org/localinfo.html

So use something like this:

!3616.98N108222.54W#PHGphgdW1........,,,,,,,,,,

Where:

phgd are the correct PHG data
W1........ Are 10 bytes on first line of D7 displays
,,,,,,,,,, are 10 bytes on 2nd line of D7 displays
;;;;;;;;   are 8 more bytes that show on D700's

Something like that.  The www.aprs.org/fix14439.html has
settings for most types of digipeaters, it has a link to the
DIGI_NED web page and a settings file for the New-N paradigm,
but I just looked through it and if I am understanding it
correctly, I hav esome concerns.

1) It says it "drops" any path greater than N.  Actually, that
is not a good idea, because how can we fix the network unless we
can see what actions a given digi is taking.  The proper way to
limit paths is not to DROP it, but to digipeat it once, but mark
it as USED UP so that it goes no further.  This lets the sysop
and everyone in the area see how the digi is taking action on a
packet considered excessive in this area.

2) It operates preemptively on WIDEn-N and SKIPS over any prior
WIDE1-1.  Again this is an improper acton, since the sender
assumed that he would get a total length of 2 hops.  So the 2
hop path receommended in most areas is WIDE1-1,WIDE2-1 so that
the packet goes two hops.  It appears that DIGI_NED
pre-emptively will ignore the first WIDE1-1 and do and immediate
hop on the WIDE2-1, which effectively limits the user to only
one hop.  

This is an incorrect interpretation of the preemptive
digipeating.  Pre-emptive digipeating only applies to discrete
calls.  That is, it allows a SPECIFIC digi to notice its
callsign somewhere in the string and to then act on that
immediately.  Thus, by definition, pre-emptive digipeating
should never apply to generic ALIASES such as WIDEn-N, because
those are not directed to any digi in particular, so there is no
reason for a specific digi to pre-emptively act on it.

In my opinion anyway...

Bob, WB4APR




More information about the aprssig mailing list