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In various parts of the country I have also narrowed it down twice to two
different RF issues.<br>
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.<br>
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).<br><br>
In both cases above these happen to be on KPC-3's. I have never bench
proven if this could occur with other TNC's/Firmware versions.<br><br>
I have seen delays from I-Gates as well cause the problem, but have never
PROVEN whether it was a slow computer/local connectivity problem, or a
problem with the APRS server it was attached to.<br><br>
Mark Cheavens<br>
KC5EVE<br>
At 10:03 PM 8/25/2006, you wrote:<br>
<blockquote type=cite class=cite cite="">Recently kc4pl and I saw
enormous delays on RF. We've seen igate delays from ww6jc in a
nearby town running ui-view. At anyrate, kc4pl is running TNC-x and
an ax.25 stack connected to javaaprs. What we saw was /were delays
on the order of 60 to 90 seconds. I was sending packets that were
uniquely numbered so we'd know which got thru and which didn't.
<br>
<br>
We suspected that perhaps TNCx was hearing too many packets on frequency
to TX, so he QSY'ed the radio. I send a few more packets.
Then it dawned on us that he wasn't seeing the packets I send for 60 to
90 seconds. As soon as he saw them appear in the ax.25 stack, they
were digipeater. In the process of reaching under the desk, he may
have reset or momentarly interrupted the power to the TNCx.... so we're
not sure if the tnc-x is the problem or the ax.25 stack in linux.
Or maybe some part of the system needed a break. At this time, we're
waiting for the delays to happen again so we can figure out if it's TNC-x
or ax25 stack. <br>
<br>
Possible theories include that TNCx may have a memory leak...<br>
tncx may spend so much time servicing interrupts in a busy channel that
it can't deliver data to the serial port.<br>
ubuntu ax25 may have a problem.<br><br>
Really don't know anything difinitive at this point.<br>
Wes<br>
<br>
On 8/25/06, <b>Tim Cunningham</b>
<<a href="mailto:tim_cunningham@mindspring.com">
tim_cunningham@mindspring.com</a>> wrote: <br>
<dl>
<dd><font size=2>There was a delayed packet discussion specifically
concerning IGates recently. We did a through study into the problem in my
area and isolated the problem to a UI-View station operating as an IGate.
Since that discussion there were a few other folks across the country who
wrote off-line that they experienced the same issue with UI-View in their
areas. This issue was specifically limited to a UI-View IGate that was
injecting packets greater than 1 minute later than another IGate using
APRS+SA. Many of the packets were time stamped to verify the delay. It
was not a digipeater delay because we could see two IGates hearing the
same packet from the same digipeater being injected into the APRS-IS
greater than one minute apart. <br>
</font>
<dd> <br>
<dd><font size=2>IGates that are experiencing delays should consider
using filtered port 14580 and limit their data to under 100 to 200km
using the m/100 to m/200 qualifier. When an IGate tries to process the
full feed they are going to run slower depending on their computer
configuration and whether they are using a dial-up feed or a high speed
link. <br>
</font>
<dd> <br>
<dd><font size=2>There are many sources of delays that also include
digipeaters. The first step is to identify if the delay is the USB to
serial converter which should be fairly easy by visual observation on how
long it takes a decoded packet to appear on the screen. Then, it becomes
only a measure of time from that point to when it appears on the APRS-IS.
<br>
</font>
<dd> <br>
<dd> <br>
<dd> <br>
<dd><font size=2>73's,<br>
<dd>Tim - N8DEU<br>
<dd>Huntsville, Alabama<br>
</font>
<dd> <br>
<dd> <br>
<dd> <br>
<dl><br>
</dl>
<dd>----- Original Message ----- <br>
<dd>From:</b> <a href="mailto:w0jrt@yahoo.com">J T</a> <br>
<dd>To:</b> <a href="mailto:aprssig@lists.tapr.org">TAPR APRS Mailing
List</a> <br>
<dd>Sent:</b> Friday, August 25, 2006 1:26 PM<br>
<dd>Subject:</b> [aprssig] Delayed packets (yet again)<br><br>
<dd> <br>
<dd>In one of the many "delayed packet" discussions there was
talk about some serial-to-USB converters causing issues. I can't
seem to find this discussion in the archives. Does anyone recall
the make(s)/model(s) of the serial-to-USB converters that are known or
suspected of being problematic? And perhaps suggest a model that is
known to work well? <br><br>
<dd>I've been communicating with an I-gate owner whose station is
injecting delayed packets into APRS-IS. He's too busy to study and
fix the problem (unfortunately for the rest of us) so I'm trying to help
gather some information that may make it easier to debug the
problem. He swapped TNCs but that didn't fix it. He mentioned
that he uses a serial-to-USB converter so hopefully I can talk him into
experimenting with a different one or coming up with another solution.
<br><br>
<dd>-Jerome, W0JRT<br><br>
<br>
<dd>
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