One of the reasons I love HN!!! Nicely written and informative post, cheap and practical stuff, lots of interesting links, comments with extra info... I’m so definitely building a receiver with my spare RPi3.
Flightradar24 – how it works
81–90 of 160 posts
Re: Flightradar24 – how it works
#82Earlier quoted context omitted.
Unfortunately, there is no good solution for this. Either you rely on the time settings of the sender or on the time needed to transmit the data and on the time the data gets transmitted.
A radio receiver with a GPS time base doesnt seem that tricky.
If we assume the sender is not malicious, a properly configured NTP client ("the time settings of the sender") would probably suffice. If the sender is malicious, unless you somehow make the "signal + timestamp" from the receiver non-modifiable from the receiver to the service, you've lost anyway.
Re: Flightradar24 – how it works
#83I’m assuming there is more to it than just the radio data?
In FR you can see planes everywhere, including thousands of miles off shore.
My guess is that FR24 just looks up the flight path from the flight number, and then once an airplane goes “off the radar” it just assumes it goes the shortest/great circle path towards its destination airport - at which point it will again be in a “known” spot? If this is how it’s done then one should see lots of planes approaching e.g the US east coast suddenly “shift” from their estimate position to their transponder positions, as they are picked up by receivers.
Re: Flightradar24 – how it works
#84Someone put ADS-B on a satellite a few years ago, it looks like this has been done more recently as well:
Re: Flightradar24 – how it works
#85I’m assuming there is more to it than just the radio data? In FR you can see planes everywhere, including thousands of miles off shore. My guess is that FR24 just looks up the flight path from the flight number, and then once an airplane goes “off the radar” it just assumes it goes the shortest/great circle path towards its destination airport - at which point it will again be in a “known” spot? If this is how it’s d…
But you can see for yourself aeroplanes far over the ocean clearly not following a great circle route, presumably avoiding weather patterns.
Re: Flightradar24 – how it works
#86I’m assuming there is more to it than just the radio data? In FR you can see planes everywhere, including thousands of miles off shore. My guess is that FR24 just looks up the flight path from the flight number, and then once an airplane goes “off the radar” it just assumes it goes the shortest/great circle path towards its destination airport - at which point it will again be in a “known” spot? If this is how it’s d…
But you can see for yourself aeroplanes far over the ocean clearly not following a great circle route, presumably avoiding weather patterns.
Interesting. So how does that work in FR24? If there was a service to get this data over long distances, then all these short range receivers would be unnecessary. So something is missing in “how does FR24 work” when it comes to that data.
Re: Flightradar24 – how it works
#87Earlier quoted context omitted.
A radio receiver with a GPS time base doesnt seem that tricky.
If we assume the sender is not malicious, a properly configured NTP client ("the time settings of the sender") would probably suffice. If the sender is malicious, unless you somehow make the "signal + timestamp" from the receiver non-modifiable from the receiver to the service, you've lost anyway.
Because MLAT relies on multiple devices, it should be straightforward to identify and blacklist a sender tampering with timing data.
Re: Flightradar24 – how it works
#88Earlier quoted context omitted.
But you can see for yourself aeroplanes far over the ocean clearly not following a great circle route, presumably avoiding weather patterns.
Interesting. So how does that work in FR24? If there was a service to get this data over long distances, then all these short range receivers would be unnecessary. So something is missing in “how does FR24 work” when it comes to that data.
[deleted]
Re: Flightradar24 – how it works
#89If you use macOS you might enjoy my app Max Planes [1]. It displays all the ADS-B data, tracks planes on a MapKit view and allows you to save and replay logs. Also I have an open source Mac app [2] to act a network server for the USB device. It contains a copy of dump1090 with everything statically linked so you don't need to build anything yourself. Just plug in the dongle and launch the app. It is codesigned, sandb…
Very nice ADS-B viewer for macOS! Quickly got it connected to dump1090-mutability once I set the bind host to 0.0.0.0 instead of localhost. I wish planes were differently colored based on certain characteristics, much like OpenADSB on iOS (the best ADS-B app IMHO)
EDIT: Also, do you support MLAT?
Re: Flightradar24 – how it works
#90Earlier quoted context omitted.
But you can see for yourself aeroplanes far over the ocean clearly not following a great circle route, presumably avoiding weather patterns.
Interesting. So how does that work in FR24? If there was a service to get this data over long distances, then all these short range receivers would be unnecessary. So something is missing in “how does FR24 work” when it comes to that data.
Probably satellite ADS-B receivers like from: https://en.wikipedia.org/wiki/Aireon