[OZAPRS] Igate to RF

Ray Wells vk2tv at exemail.com.au
Mon Aug 30 07:54:54 EST 2010


Howard,

aprs usage and traffic density varies greatly across this vast country 
and, a one size fits all just doesn't fit.

I'm in Kempsey and run both the hf/vhf igate and the local digi. Apart 
from the digi beacons and my occasional igate beacon there is just one 
other fixed station (vk2cvr) and my "seldom on" mobile signal. There is 
the occasional traveller passing through but there is no constant local 
mobile activity to maintain user interest in aprs.

The nearest "next" digi to here is 115km away.

To provide a bit more interest involving a wider geographic area I 
permit a select few out-of-area stations to be broadcast on RF. This is 
being constantly reviewed with regard to channel traffic, which is very 
light, even at the busiest of times.

It's safe to say that most traffic via the local digi is weather related 
- warnings and current wx at 9 regional wx stations.

If you live in a densely populated area the concept of wanting to know 
about things hundreds of km away is probably foreign to you. For someone 
in a lightly populated region those other towns are as local as someone 
in the next suburb in Sydney or Brisbane.

Armidale, for example, is 125km away from Kempsey, as the radio travels. 
Kempsey has considerable interest in the wx (rainfall) at Armidale 
because the Gara River, north of Armidale, flows into the Macleay River. 
It was melting snow in the Gara River that was largely responsible for 
the devastating 1949 Kempsey flood. We definitely consider Armidale to 
be "local".

It's all very well having guidelines but they don't provide for every 
situation, nor can they ever. Having "guidelines" permits things to be 
done a little differently, provided "different" doesn't impact the wider 
network; the impact of different must be purely local.

And having guidelines doesn't stop individuals completely misconfiguring 
in an ad hoc way to cause havoc in densely populated areas.

It should be more about common sense than strict adherence to rules. If 
we bend the rules to suit the local environment we should also be 
prepared to bend them back when circumstances change. One day I will 
have another digi in range of vk2rmc-1. When that happens I will review 
my settings. Until that time there is no need and, I suspect Warren 
feels the same way.

Ray vk2tv


On 30/08/10 05:48, Howard Small wrote:
>    This puzzles me as it suggest that APRS only has value if the VHF
> frequency is swamped with packets that are of no use or interest locally.
>
> This flies in the face of the guidelines as stated on www.aprs.net.au:
>
> " The I-Gates feed packets heard off-the-air in their vicinity into the
> IS, and under some conditions allow Internet data to go back to RF."
>
> "APRS was developed to convey LOCAL real-time information. As such, we
> are aiming to minimise the amount of NON-LOCAL data that is transmitted
> on the VHF network. Although it may be nice to see the location of every
> repeater in the country, getting the data to your display via RF
> prevents several mobile stations in the local area from accessing the
> network due to the high collision rate.
>
> For these reasons, the 2m network is generally configured to maximise
> the availability for mobile/portable stations. The amount of data
> transmitted from the internet to the VHF network is minimal, so as to
> allow the maximum amount of airtime for mobile trackers to send thier
> data into the network.
>
> In some areas a 70cm APRS network has been established that carries
> additional traffic, making it available via RF, yet keeping the
> congestion away from the primary 2m frequency to allow the mobile and
> portable stations to use APRS as it was intended."
>
> Howard
> VK4BS
>
>
> On 21/08/2010 18:15, ozaprs-request at aprs.net.au wrote:
>    
>> Message: 4
>> Date: Sat, 21 Aug 2010 17:50:19 +1000
>> From: "Warren VK3BYD"<vk3byd at wia.org.au>
>> Subject: Re: [OZAPRS] iGates and RF
>> To: "'Australian APRS Users'"<ozaprs at aprs.net.au>
>> Message-ID:<000001cb4105$838e15c0$8aaa4140$@org.au>
>> Content-Type: text/plain;	charset="us-ascii"
>>
>> If we change our Igates to only feed messages back out on RF, I might as
>> well give up on APRS.
>> I would only see the local Digi's and two mobiles on the map,
>>
>> Warren.
>>
>>      
>
>
>
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> OZAPRS at aprs.net.au
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>
>    



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