[aprssig] KPC3+ induced errors

[Stephen H. Smith]

On 3/27/2011 1:59 PM, Andrew Rich wrote:
> Is it a genuine delay?

YES

>
> Are packets lost ?

Apparently not.  It acts as though some sort of buffer fills up, and then the 
oldest packet gets pushed out when a new one arrives.  Depending on the volume 
of traffic on the channel, this FIFO buffer effect can cause packets to delayed 
anywhere from  10s of seconds to 10s of minutes.

>
> Is it a flow control issue ?

It shouldn't be since KISS doesn't use flow control.

A similar issue arose with a Kenwood D700's internal TNC being used for an 
igate for a balloon launch in Colorado. In this case, operating in NON-KISS 
mode with UIview with X-On/X-Off flow control enabled, long delays were 
experienced.   Setting the flow control in UIview to "None" eliminated the 
problem.  [ I suspect that random bytes in binary telemetry steams (or 
corrupted incoming packets) were being interpreted as X-On(11 hex or Ctrl-Q) ) 
and X-Off (13 hex or Ctrl-S) control characters. This would cause the data flow 
from the TNC to the PC to randomly stop and then later resume. ]
>
> Does the test setup use no flow control ?

Correct

-------------------------------------------------------------------------------

--

Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

=====  Vista & Win7 Install Issues for UI-View and Precision Mapping =====
     http://wa8lmf.net/aprs/UIview_Notes.htm#VistaWin7

*** HF APRS over PSK63 ***
    http://wa8lmf.net/APRS_PSK63/index.htm

"APRS 101"  Explanation of APRS Path Selection & Digipeating
   http://wa8lmf.net/DigiPaths



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.tapr.org/pipermail/aprssig_lists.tapr.org/attachments/20110327/677b0f0e/attachment.html>