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[aprssig] packet delays through internet

Heikki Hannikainen hessu at hes.iki.fi
Mon Mar 21 05:19:36 UTC 2011


On Sun, 20 Mar 2011, Stephen H. Smith wrote:

> On 3/20/2011 1:07 PM, Russ Chadwick wrote:
>> 
>> Significant packet delays were noted through an I-gate that consisted of a 
>> D710, UI-View and Comcast ISP.  We (Mark, KC0D; Nick, N0LP; and I) did 
>> tests yesterday and found the problem to be that UI-View was using Xon/Xoff 
>> flow control while the D710 was not using flow control.  Delays of a few 
>> minutes to 90 minutes were noted with this set-up.
>
> Arrrgh!!!     Xon/Xoff is asking for trouble, especially on radio data links, 
> since any value from Hex 00 to Hex FF is possible in an incoming byte, 
> especially if it is corrupted in any way.    Xon/Xoff flow control consists 
> of binary characters transmitted over the same TXD/RXD conductors as the 
> incoming and outgoing data.

Jumping back to the KPC-3+ ...

Could someone confirm that this cannot affect the KPC-3+ problems? Could 
it go to Xoff mode (not transmitting to the host) for a while, and when 
the buffer finally fills up, start transmitting again from the other end 
of the buffer?

Or does the KPC-3+ delay grow gradually over time? Alan?

   - Hessu




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