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

Steve Dimse k4hg at tapr.org
Tue Dec 14 14:51:14 UTC 2004


On 12/13/04 at 11:22 PM Tate KC7ZRU <kc7zru at arrl.net> sent:

>I do believe that's exactly with the number of stations listed is
>included. Simple presence on the list isn't what counts - it's that
>number of stations. Such stations that see 60 and over (300??!! Must be
>the upper limit in the script, eh?) are the ones being addressed here.
>
Yes, I maxed out the count at 300. This script already takes quite a while to
execute, and numbers higher than that are essentially meaningless. This was
meant as a screening tool, not to make a good/bad binary decision.

As has been pointed out, it would have been less confusing had Bob sorted by
counts and removed those under 60, as has been pointed out these are probably
(assuming the PHG calculated range is not too low) not flawed digis.

I think Bob is over-using the data I provided. When I last did this for him (23
months ago), I hope I explained the pitfalls to him, but in any case I didn't
repeat them this time, my fault...

Here is a static page of the results I gave him:

http://www.findu.com/digi.html

Find your favorite digi and follow along...

First, these numbers are only as good as the PHG range, look at the number
calculated for your digi, if it is OK, click on the callsign to see the list of
stations in that range. If there is an error in the range, then edit the URL as
needed. 

Next, the station count will be high for most digis, as there is no removal of
HF, Internet only, WinLink, ARISS, and PCSat stations. Look through the list to
see how many of these are not actually on the VHF RF LAN. 

Then look at the packet rate numbers for each of the stations in range...a badly
behaved mobile sending a posit every minute is much worse than a home stations
sending nothing but a posit every 30 minutes. Remember that because of dup
checking, findU can only count unique packet payloads, most of these packets
generated multiple transmissions on a local RF network.

Finally, look at the number of digis in range, and how much traffic they have,
which dramatically affects channel loading.

Because of the dup checking features of the APRS IS it is impossible for findU
to look at things and automatically determine what is a good or bad digi...findU
can provide tools to help, but each digi must be looked at indivually by a human
brain. Do not blindly follow data, look at it, understand how it was derived and
what its limitations are, and then you can use data intelligently!

Steve K4HG




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