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[aprssig] What is happening ? (long delayed packets)

J T w0jrt at yahoo.com
Thu Jul 31 14:13:15 UTC 2008


There are many things that can cause long delayed packets on RF.  This has been brought up before so a search through the message archives may provide some more clues.

Some USB to serial converters can cause this.  If ZL1VFO is using one of those it would be another thing to check.  Some Belkin and similar cheap units have been known to be unreliable in this regard.  Keyspan brand is good.

A while back someone reported seeing delayed packets from a station using TNC-x and the AX.25 stack in Linux.

Mark Cheavens reported a few more things that he's seen cause this:
"In various parts of the country I have also narrowed it down twice to two
different RF issues.

1. I found a TNC/Radio combination that was not using DCD, but was
instead using squelched audio for the TNC to decode. When the squelch was
left OPEN, the TNC would not transmit until it's internal buffer got full
and then DUMPED the entire contents of  it's buffer in one
continuous stream.

2. Similar issue as above, but the root cause was a digi that routinely
heard a continuous stream of packets from so many other digi's that it
would also que all the messages until it's buffer got full and then would
do a DUMP of it's contents. (It could hold about 2 minutes of continuous
packets when it did transmit)."






      
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