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[aprssig] Re: Feeding multiple stations into one for digipeating?

Steve Dimse steve at dimse.com
Mon Jun 12 00:12:16 UTC 2006


On Jun 11, 2006, at 7:46 PM, Patrick Green wrote:

> I wanted to state that what I'm trying to do is capture small
> trackers better.  This is no different than what a multi-receive
> site repeater does.  It has a "voter" that takes the best quieting
> signal and transmits it.  I want to do the same here, If I have 4
> copies of the same packet each from 4 different participating
> receivers and the packet is eligible for retransmission, only 1
> copy gets sent out over RF.  The central digi will still be CSMA
> to the other traffic on channel.  I want to use the internet as the
> medium to bring the traffic to the central digi.

Just so you understand the reason passions may be aroused by your  
proposal, consider that the APRS Internet System is really the  
world's largest diversity receiver system. There are hundreds of  
participating receivers, not just four. The APRS-IS removes all the  
duplicates from multiple receivers, yet clearly trying to force the  
stream back out on RF is not going to work. That is an extreme  
example, but when you talk about the system you are describing, the  
concern some people have is that it will degrade the local RF  
network. In an area with low traffic loading, using outlying  
receivers feeding a central transmitter may improve things, but in an  
area with moderate to high RF traffic, it will make things worse.

I'm sure this thread will soon delve into arguments about ALOHA,  
CSMA, and so on, but keep in mind the first thing a young doctor  
learns: "First do no harm"!

Steve K4HG 




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