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Flightradar24 – how it works

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Re: Flightradar24 – how it works

#51

Post by loeg »

sorenjan wrote: post #37
dewey wrote: post #25

Earlier quoted context omitted.

I thought it would be cool to have some kind of gateway service that collects the data and then sends if off to adsbexchange, flightradar and others but apparently it's not so easy. Someone else already asked this question before: https://www.reddit.com/r/ADSB/comments/ar3qrw/feed_to_a_sing...

Do you mean collect data from multiple receivers and send it off to various services from one computer? That messes with MLAT [0] calculations and shouldn't be done. If you want to send data to multiple services from one receiver all you need is to install the feeder for each service. Most uses dump1090 [1], but Flightradar24 uses their own. Dump1090 sends data in different formats to various local ports by default,…

Do you have more detail on how collection messes with MLAT calculations? It seems like for triangulation purposes, each device should produce some precise timestamp that is not affected by store-and-forward transmission.

Re: Flightradar24 – how it works

#52

Post by loeg »

jacobreg wrote: post #15
fergbrain wrote: post #3

“Every civilian airliner is equipped with a special device — the so-caller ADS-B (Automatic Dependent Surveillance-Broadcast) transponder” Not true actually: in the US, ADS-B isn’t required until January 1, 2020 [1]. Also, FR24 uses radar data in the US (probably because not all aircraft has ADS-B) [2]. There are also sites, such as ADS-B Exchange [3] that provide unfiltered flight data...very helpful for tracking mi…

Even after 2020 ADS-B out won't be required in much of the airspace in the US. Only within 30 nautical miles of a class B airport, within the lateral limits of a class C airport, within class D airspace, and above 10k feet (but not below 2500 AGL I think). Even then, its only required for aircraft originally equipped with an alternator and electrical system (except in class B). Basically, it's optional in most uncont…

In practice, anything that can be described as an "airliner" is a large commercial aircraft and flies above 10k regularly. Probably required to have ADS-B.

Re: Flightradar24 – how it works

#53

Post by theyinwhy »

loeg wrote: post #51
sorenjan wrote: post #37

Earlier quoted context omitted.

Do you mean collect data from multiple receivers and send it off to various services from one computer? That messes with MLAT [0] calculations and shouldn't be done. If you want to send data to multiple services from one receiver all you need is to install the feeder for each service. Most uses dump1090 [1], but Flightradar24 uses their own. Dump1090 sends data in different formats to various local ports by default,…

Do you have more detail on how collection messes with MLAT calculations? It seems like for triangulation purposes, each device should produce some precise timestamp that is not affected by store-and-forward transmission.

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.

Re: Flightradar24 – how it works

#54

Post by loeg »

tyingq wrote: post #47

It updates position and transmits once per second. I wonder if that makes it useful as a homing signal for a missile. Or perhaps the position resolution isn't close enough for that?

GPS isn't really precise enough for that and targeting civilian aircraft is easy anyway; this isn't much of an additional attack vector, IMO.

Re: Flightradar24 – how it works

#56

Post by usr1106 »

In Germany receiving ADS-B used to be illegal (I don't think it has changed, but I did not verify.)

In Finland receiving as such is not illegal, but forwarding the information is.

In both cases the reasoning is that this information is not directed to the public. Whether anybody has ever been prosecuted I have no idea.

Re: Flightradar24 – how it works

#57

Post by Moru »

tyingq wrote: post #47

It updates position and transmits once per second. I wonder if that makes it useful as a homing signal for a missile. Or perhaps the position resolution isn't close enough for that?

Not so useful for a plane traveling at 800 km/h. And it's transmitted with radio so anyone can pick it up without internet. But if you want to fire something at a plane there are much easier and cheaper things to use from the ground.

Re: Flightradar24 – how it works

#58

Post by tyingq »

loeg wrote: post #54
tyingq wrote: post #47

It updates position and transmits once per second. I wonder if that makes it useful as a homing signal for a missile. Or perhaps the position resolution isn't close enough for that?

GPS isn't really precise enough for that and targeting civilian aircraft is easy anyway; this isn't much of an additional attack vector, IMO.

I suppose the benefit of knowing where everything is a security plus. Watching 9/11 documentaries, it was surprising how many aircraft the controllers couldn't account for.

(Though this does seem spoofable.)

Re: Flightradar24 – how it works

#59

Post by jacobreg »

loeg wrote: post #52
jacobreg wrote: post #15

Earlier quoted context omitted.

Even after 2020 ADS-B out won't be required in much of the airspace in the US. Only within 30 nautical miles of a class B airport, within the lateral limits of a class C airport, within class D airspace, and above 10k feet (but not below 2500 AGL I think). Even then, its only required for aircraft originally equipped with an alternator and electrical system (except in class B). Basically, it's optional in most uncont…

In practice, anything that can be described as an "airliner" is a large commercial aircraft and flies above 10k regularly. Probably required to have ADS-B.

Oh whoops, I misread as "airplane"

Re: Flightradar24 – how it works

#60

Post by tyingq »

Moru wrote: post #57
tyingq wrote: post #47

It updates position and transmits once per second. I wonder if that makes it useful as a homing signal for a missile. Or perhaps the position resolution isn't close enough for that?

Not so useful for a plane traveling at 800 km/h. And it's transmitted with radio so anyone can pick it up without internet. But if you want to fire something at a plane there are much easier and cheaper things to use from the ground.

I didn't mean the internet part...ADS-B in general.
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