Justin Albury justin at jacomms.com
Thu Sep 25 21:53:32 EST 2014

So to remove a few of these issues we have done a new config and alignment of a replacement VK2RHR-1 digi as a "hot swap" .... this will be more of a fill digi rather than it current config.

As soon as I get a chance I will visit Highrange and do the swap.

Will keep you posted


Justin Albury
J Albury Communications
justin at jacomms.com

-----Original Message-----
From: OZAPRS [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of Owen Duffy
Sent: Thursday, 25 September 2014 6:01 PM
To: Australian APRS Users
Subject: Re: [OZAPRS] MICE usage

Hello All,

Some thoughts on the issue:

I think the real issue here is the failure of source routing, whether you give it some grand name like "New N Pardigm" or not.

There are numerous examples that demonstrate that you cannot depend on hams, whether they operate end stations or 'infrastructure' (digis,
iGates) to "do the right thing'.

Hams doing what they want as individuals were responsible for the demise of the old 'packet network' before its time, and the same problem occurs with APRS.

So, if you drive outside Sydney or Melbourne for your annual holidays, and you set your path for WIDE1-1,WIDE2-2, what is wrong with that?

Well the issue is that the optimal path is not a property of the mobile, but its location. In some places, a single hop is sufficient to have a high probability of iGate submission, in others, three hops might only moderate probability of iGate submission.

Then there are the  effects of band openings (most mornings and evenings in summer) where three hops may well get you from Sydney to Melbourne.

A possible solution is intelligent network infrastructure that controls packet routing, and limits the lifetime of packets. It could also be used to block misguided stations operating outside of reasonable parameters on the shared radio channel.

That means finding a flexible routing platform for digis, especially strategic digis that could be used to segment the network into local areas as congestion dictates. Such a platform needs to be highly interoperable, there is no room for a digi that does not decode some popular trackers (eg the incompatibility between OT3 and Foxtrack/TT1).

Sydney is a most interesting case study, it has essentially no 'local'
digi and depends on three digis 40-60km out, and most packets that originate or enter the area are repeated by all three digis so increasing channel utilisation which in turn reduces the effectiveness of the network for position reporting of mobile stations.

A filtering dig in each of the three locations to block traffic flow from north to south, and south to north could be very effective in reducing channel utilisation whilst still support high rate of iGate submission.

The role of High Range and Mt Murray, both W2 digis located with 40km of each other deserve review as under the "New N Pardigm", almost all packets originating in Sydney and the Illawarra carried by one will be carried also by the other.

At the same time, coverage of half of the M7 is patchier than a lot of major highways outside of Sydney.

I think it is the infrastructure that deserves attention rather that trying to educate end users.



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