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[aprssig] APRS low-power-local ALT input channel

J. Gary Bender, WS5N WS5N at mindspring.com
Mon Sep 27 17:14:35 UTC 2004


I think you are ignoring the fact that DIGIpeaters are not real-time 
REpeaters.  They are store and forward devices.  It is SOP for packets, 
received from any source, to be stored on-board the digipeater until it 
is able to transmit on a clear channel.  I doubt that the thought of 
digipeating on to .39 blindly was ever considered -- it just is not the 
way the machines work.

The alt/input 144.99 proposal is a collision avoidance device in it's 
own right.  It is a good and workable engineering compromise.  It puts 
the most susceptible devices, and most likely to collide, on a channel 
with a much lighter load and no high power stations.

One of the reasons I abandoned packet 10 years ago was because of the 
"hidden station" problem.  APRS, because it took the limitations of a 
simplex network into account, works fine in that environment.  I was 
taken aback when I saw deaf trackers so popular on APRS -- however, if 
the network could not handle them, they would not be so popular.  This 
proposal gives the little trackers a much better chance.
--
J. Gary Bender, WS5N
Tijeras, New Mexico  USA

On Sat, 25 Sep 2004 23:11:35 -0500, Robbie - WA9INF wrote:
> Gents,
> 
> 
> I hope this never takes place on a wide scale. Special events, yes,
> maybe it may work temporarily without too much detriment to the other
> users.
> 
> To advocate listening on one frequency and transmitting on another
> without some kind of CD, is asking for some serious kind network
> failures!
> 
> I am not aware of any trackers or base stations or digipeaters that do
> this now. If a tracker can not hear another station or CD, then it has
> the right to transmit. If a digipeater, or base station, does not hear
> another station, or NO CD, then it has the right to transmit..
> 
> But to just blatantly come up and digipeat a low power signal from
> another frequency with out CD on 144.390, is "intentional interference".
> It is not Aloha. Isn't Aloha "Transmit if you don't hear another
> station" and the digipeaters or home RELAYs will sort it out?
> 
> Even in a busy area like Chicago, I can track several 5 watt trackers
> when they are on.
> 
> I hope this can be sorted out before hundreds of stations jump on this
> without fully understanding what may happen..
> 
> Robbie







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