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

Mark Cheavens mcheavens at usa.net
Thu Jul 31 10:38:10 EDT 2008

Another item is if packets get reversed gated, make sure that the 
reverse gating station uses NOGATE in any path.

Mark Cheavens
At 09:13 AM 7/31/2008, you wrote:
>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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