[aprssig] Re: Fill-in Digis

John Ronan jronan at tssg.org
Fri Mar 24 11:04:36 CST 2006

> The thing that most people overlook about fill-in
> digis, is that the concept gives us a 2 tier tool
> to balance the ability of a distant mobile "geting
> into a digi" compard to his ability to hear a digi.
> There is a huge inbalance here, And I mean BIG.

> The Fill-in digi attempts to better balance that
> situation.  THink of the tier of out-lying fill-in
> digis as just like a big voice repeater with remote
> site receivers.
> Please consider:
> 1) A mobile's ability to get into a big digi the
> farther out from it he is, is *mostly* limiited
> in his lack-of-ability to hit the digi strong
> enough to overcome all the surrounding
> QRM from all other digis and all other stations.

> 2) But he hears the digi just fine at the same
> distant location.


What we have experienced is exactly the opposite, I can get into the  
Digi, but not be able to decode the forwarded on packet (can hear it/ 
see the S meter rise though).

> The FILL-in digi being closer to him will pick up
> his signal quite well and give it a better chance
> of getting into the big digi.    But, being a fill-in
> digi, it will NOT add to the QRM by making
> unneeded copies of 100% of all the other
> traffic on the channel.
Ok, as we say over here "I stand under you now", thats a subtle  
point, worth remembering, but I think what we have experienced, being  
the opposite of what you seem to experience only makes for an  
asymmetric network, which would be/is confusing for users.

>> In fact I think I'm just going to  recommend
>> that to WIDE2-2 should be the default.
> What this does is tie your hands at requiring
> every digi to always digipeate 100% of

As our experiences differ, we will agree to differ for the moment, if  
our network ever gets that busy here, we'll hopefully have a better  
'moustrap' built to deal with it :) With the deployment we have  
coming up next weekend (10-15 trackers on two sides of a mountain  
range, all back to one ICP), I may have to change my tune afterwards.

de John

John Ronan <jronan at tssg.org>, +353-51-302938
Telecommunications Software &  Systems Group,  http://www.tssg.org

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