[aprssig] FEMA - APRS Blackout data wanted...
info at wirelessmapping.com
Sat Sep 10 07:37:17 CDT 2016
I like this idea.
Would you want to somehow figure out which stations have more than one I-gate available (and preferably with different internet providers)? The blackout you may be trying to illustrate could be showing an i-gate outage or an internet outage if you are not trying to look at the data strictly off air.
I would think though that most APRS stations have some sort of battery power that would delay or mask any blackout areas.
One idea for your display if this does seem to illustrate what you want; in the GIS/mapping software world we can create a polygon using the encompassing points. For your purposes this would more quickly illustrate the possible area of issue. You might also set a parameter of a certain number of points to be required before drawing the polygon. This would help minimize anomaly data.
From: aprssig [mailto:aprssig-bounces at tapr.org] On Behalf Of Robert Bruninga
Sent: Thursday, September 08, 2016 8:17 PM
To: TAPR APRS Mailing List
Subject: [aprssig] FEMA - APRS Blackout data wanted...
The Technology Office at FEMA asked me about using APRS data... THey want DATA on anything they can get. For example, to visualize power blackouts.
I answered "It's in there!"
All we have to do is plot it.
Here is an approach I would try for any WEB based APRS map displays.
1) Keep at least 5 bits on every WX and HOME station and DIGIPEATER
2) Every 11 minutes decrement every such stations counter by 1
3) Every time a new packet is heard, increment the counter by 10
Now then any station with a count greater than 9 is considered a >90% reliable 24/7/365 station (has been heard in the last 30 minutes too) We can call these 24/7 stations.
Now when someone asks for a BLACKOUT PLOT, display two things:
All stations that have been heard in the last 10 minutes... (live stations)
AND *greyed-out* symbols for all of the 24/7 stations (blackout stations) that have not been heard in 30 minutes.
BINGO, done. We have the data, just need to come up with the right algorithm and the best way to display it.
The original APRSdos sort of did this by fading-to gray all stations not heard in the last X minutes, This worked great locally because we each generally knew all the symbols there were normally there 24/7 and conuld instantly visualize something was wrong when they all faded to gray in an area. (but were still on the map)
But for huge APRS-IS systems, there needs to be the algorithm to know which stations area always on, so they can then indicate when the disappear..
Sure, lots of reasons why this is not going to be pergfect, but it does give a QUICK indication that something has changed and eeds further investigation...
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