[OZAPRS] APRS 'idea' ? - needs some clarification

[Ben VK2BEN]

HI Paul,

I think there is a profound question in your message below, but some 
clarification is required to give you a satisfactory answer.

After rephrasing your entire question in a couple of different ways here 
in my head, I think I may have deduced what you might be asking:

Are you suggesting that, instead of multiple stations (by which you 
might mean "digipeaters"?) re-transmitting all APRS packets that it 
hears over the air, or gathers from an Internet Gateway ("iGate") in a 
given area; that only "one" station should do this and cover a really 
large geographical area?

Well, actually that how digipeaters work in any case, so I am still not 
sure that I fully understand your proposal from the start. Digi's will 
re-transmit what they hear - within the limits set by their Wide-n 
parameters - and IS (Internet) to RF (Radio) gateways (iGate) are 
generally not encouraged [perhaps even strongly discouraged? I am open 
to correction here]  due to the massive amount of data with which they 
could potentially flood the RF channel.

Digi's are strategically placed to cover large areas [and to stretch the 
VHF network out to sparsely populated areas and even link such scattered 
areas back to the network if there are no Internet links at the regional 
areas]  and to repeat APRS posits to mobile and fixed users of that 
network who may not have received the originating signal (which is 
usually a lower-powered mobile transmitter with limited LoS range). 
Fill-in Digi's are set up in blind spots, or as links between service 
areas, that might not be covered by the regional Digipeater. These can 
be given limited range (path, as well as RF power) so as not to fill the 
channel with redundant data. Thus, I think that the short answer is no; 
we cannot realistically remove large numbers of Digipeaters in order to 
reduce traffic on the APRS channel. It would not solve many problems. 
Especially here in Australia, where the frequency can hardly be 
described as 'overloaded' ;-)

  As for reducing the amount of traffic on the frequency in a given 
geographical region; this would become a moot point because the same 
amount of APRS data would still need to be transmitted to service that 
area all at once with a single transmission. But instead of several 
short bursts of repeated data coming from a group of well-managed 
digipeater sites, it sounds like we might end up with really long (and 
perhaps more susceptible to interference and errors?) transmissions 
carrying all sorts of position data that might not be wholly relevant to 
the users in that specific area. Currently, Digi's are dispersed so as 
not to cover the same areas as each other, nor with too much overlap. At 
the same time, protocols are in place (within the TNCs) to disallow 
indiscriminate repeating of data and thus unending loops of repeated data.

I think there is a fine balance between covering all areas well with as 
few digipeaters as possible, whilst at the same time filling in valleys 
and great open spaces with the required positioning data. The way the 
system works right now is pretty darned good. And after reading thru 
parts of the aprs.org website, I am surprised that anybody can 
understand it at all :-P

Paul, I apologize if I have extrapolated far more from your brief 
proposal than you might have intended, but it seemed necessary to 
clarify a few things before approaching what you appeared to be asking. 
Hopefully I didn't veer off the track too far?

73,
Ben vk2ben


>> Hi there all,
>> Its been a while from my last post, I have an idea. I have no idea if this
>> has been implemented anywhere in the world but this idea could be done.
>>
>> I have been thinking about the way that the APRS network works, now I might
>> be wrong with fully understanding the network but this is my idea.
>>
>> All the sites are Receive getting data from the mobiles and passing it on to
>> a main internet link as per normal and the remote sites passing the
>> information as per normal.
>> The main difference is with a single area transmitter what gathers data and
>> what is coming from the internet is transmitted from a single site.
>> Of course as you move away from possible single site receiving maybe another
>> site could pick up the slack with another internet to RF gateway, there
>> might be another way of doing it, this I feel could reduce the traffic by
>> 25% - 33%.
>>
>> Cheers and 73s'
>> Paul
>>
>> VK5VCO
>>
>>
>> *****************************