[aprssig] KPC3+ induced errors

Michael Carey michaelcarey at internode.on.net
Wed Mar 16 15:48:40 EDT 2011

On 16/03/2011 0747, Max Harper wrote:
> This is the response that I just received back for Kantronics. I must 
> have been the only one to email them about this problem recently. Come 
> on guys, if you really what this problem fixed then you must let them 
> know just how bad this problems is. Send any information you have to
> service at kantronics.com <mailto:service at kantronics.com> even if it is 
> just to say that you are experencing the delay problem but don't have 
> any other info. I am just one voice here. I could not answer their 
> question about transmitting and receiving or just receiving.
> Max
> --------------------------------------------------------------------------------------------------------------------------------
> Max:
> I have forwarded a copy of your message to our code programmer, when I
> received your message last week. I have not heard back from him as yet.
> No one has reported having any problems in KISS mode in the KPC-3 Plus,
> anytime recently (in the last few years).
> Are the KPCs used in KISS mode only receiving, or both transmitting and
> receiving?
> Ken
> Kantronics Technical Service
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig

Hi Everybody,

Sorry for the long post...

I have seen a similar KISS & APRS delay issue... but not with a KPC3+.

I run an APRS IGate using UI-View and a Paccomm Tiny2TNC. For a while I 
was running the setup with AGWPE "in the middle". The TNC talked KISS to 
AGWPE and UIView was in AGWPE host mode. I did this so I could remotely 
monitor the local RF APRS traffic with the AGWMonitor software. Using 
this setup I was also able to have multiple UIView computers on my 
network access the same TNC.

Randomly and always after some operational time I was seeing duplicate 
packet error messages in the raw data listing on aprs.fi.

After further investigation, I found that some APRS frames received by 
the TNC/AGWPE/UIView were being delayed or held up, generally until the 
some other activity happened like a beacon frame being transmitted by 
UIView, or sometimes as another RF frame was being received.

I have two local UI-digi APRS digipeaters and both can be accessed from 
my QTH. Sometimes my APRS IGate receives three "versions" of the same RF 
ARPS frame... direct and by each digipeater. One of the digipeated 
frames would get delayed by whatever was the culprit and would then 
"appear" after the expire timer had "expired" and hence would appear to 
be a duplicated frame, even though it was the same frame... just delayed.

I was able to see what was happening by using another TNC and radio to 
monitor the local activity and also using the AGWMonitor software to 
look at what my IGate setup was receiving. Watching both at the same 
time gave me the clue as to what was happening.

I tried a KISS only EPROM and several versions of both Paccomm and MFJ 
firmware but in all cases, the delayed APRS frame issue came back.

In the end, I removed AGWPE from the equation and the problem hasn't 
come back. I assumed it was AGWPE that was causing the problem.
There has since been a new version of AGWPE released, but I haven't 
gotten around to trying it out.


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