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[aprssig] BIG-TALL digis that hear FAR too MUCH!

Steve Dimse k4hg at tapr.org
Tue Dec 14 15:20:01 UTC 2004


On 12/14/04 at 10:06 AM Robert Bruninga <bruninga at usna.edu> sent:

>Any digi that can hear more than 60 or so
>other stations is going to have more than
>a 100% saturated channel and cannot possibly
>serve locals reliably,...
>
There cannot be a simple line drawn where 59 is good and 61 is bad. Even after
eliminating non-VHF LAN stations, you must take into account packet rates of
those stations and the configuration of the local network...if one has 20
mobiles sending a NMEA packet every minute with WIDE7-7, and 10 WIDEn-n digis in
range, the channel will be massively overloaded with only 30 stations in range.

At the other extreme, say there is a digi in a place like Key West (therefore
other activity in only one direction), with only 1 other digi in that direction,
a local network could easily support 200 home stations sending a posit every 30
minutes...the channel is not overloaded despite a 201 station count.

Obviously these are extremes, and in many cases the average number of 60 is
probably as good as any, but the point is that each individual case MUST be
looked at with a human brain, you cannot rely on findU or any other computer to
answer this question in all cases...

Steve K4HG




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