FlightAware Discussions

Distant signal

This is anomalous for my station but thought it was cool.

Interesting because the flight page for UAL405 puts around Pittsburg not FT Wayne.

So it’s not a distant signal but corrupted data :slight_smile:

Don’t know how many bitflips you need for a wrong position but it’s a couple and they need to match up so the error correction still likes it.

Some 1500 messages from this source so which one is wrong? How about the 1499 other messages. I know that gig frequences rarely will go this distance unless they are in space or ducting. I do however think that a single error even several errors would not cause this. Also what kind of error correction is employed that would fail so completely.

BD

Some reading on CRC:
http://www.ciphersbyritter.com/ARTS/CRCMYST.HTM

Single bit errors are corrected by dump1090. That means you don’t need quite as many bits flipped the correct way to produce wrong data.

It does not happen often but you get a lot of packets.

While you got 1499 messages you apparently only got one position (at least two messages which were combined to one position), otherwise there would be a track visible.

Anyway i would believe instantly that this is ducting but you said yourself on the web the plane had another position. Which makes faulty data much more likely.