[aprssig] APRS-IS Duplicate Packets
Tapio Sokura
oh2kku at iki.fi
Mon May 3 15:49:56 EDT 2010
On 3.5.2010 13:48, Pete Loveall AE5PL Lists wrote:
> content (there is some attempt by javAPRSSrvr to reduce these
> duplicates, but if the trimmed packet shows up first, as in this
> case, there is not much that can be done). If your packets do not
Why can't the filtering work both ways? Currently when deciding what is
a duplicate I consider the sender callsign-ssid, target callsign and the
body of the packet. The body is considered up to the first cr or lf
encountered, not including the cr or lf itself. Also all white space
immediately preceding the cr or lf is dropped from the duplicate
checksum calculation. This seems to catch most duplicates, except those
packets that have passed through igates or digis that drop or replace
certain byte values (0-31 or above 127 usually) from the body.
Tapio
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