Statistics: Count of Distance from Feeder Not Incrementing


#1

When I received data from four distant aircraft I expected the count of positions reported to increase correspondingly but it didn’t.

Today, four aircraft moved along a distant airway in the space of an hour. From the Recent Aircraft Seen table, their distances from me when they left my sight were, 124, 134, 134 and 151 nm. Before they went over, my count in the 120-160 nm range was 3 … and it did not increase. I expected that there would have been 10 - 40 positions reported. (A nearby site did not get any credit for these either.)

My thought is that all four aircraft had been counted as seen earlier in the day. They did not appear to add to the aircraft seen count in that hour. Perhaps the algorithm used to populate the distance polar chart does not recognise positions if any unique aircraft had been previously counted.

Any suggestions or pointers to particulars for the feeder stats?


#2

If you want the most accurate representation of your coverage area you will need to do local processing. There is a tremendous about of processing FlightAware does to generate the ADSB stats page for 9000+ sites. If you need more accurate representation of the data than on your ADSB stats page you will need parse this yourself.

The local data feed can be grabbed by dump1090 that can then be parsed and counted by a program.
There is a forum post about how to do parsing and some parsing programs people have built below:
ads-b-flight-tracking-f21/ads-b-receiver-project-setup-scripts-t36532.html

I have looked at some of the parses people have put up and they are very similar to what is on the ADSB stats page. The main difference is that some planes are counted in the previous hour or the next hour. Or that some distance bins are counting the plane in a closer or father bin. The total counts in a day matches up closely between what FlightAware is showing and what people are parsing.

Also, the ADSB team is putting out a monthly newsletter. We will be including information about ADSB and what people are doing with ADSB. Parsing the local feed is definitely something people are interested in and we will probably do an article on it.