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Comment by sorenjan | Hacker News Reader

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, and ADS-b Exchange uses netcat to send it to their server. You can use the ADS-B Receiver Project [2] to install everything needed.

[0] https://en.wikipedia.org/wiki/Multilateration

[1] https://github.com/flightaware/dump1090

[2] https://github.com/jprochazka/adsb-receiver

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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.

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.

I don't think the programs are made to handle that use case. At present you register your receiver's location with the server once and send packets as they arrive, that server doesn't know that your packets are from multiple receivers at multiple locations.

https://discussions.flightaware.com/t/aggregation-of-dump109...

https://github.com/mutability/mlat-client

Thanks for the explanation. I was referring to the second use case and I didn’t know it’s so easy. So I guess it’s not that big of a problem.

If you aren't trying to send MLAT data to more than one server, it isn't an issue. You can do MLAT to, say, adsbexchange, and non-MLAT to flightradar24.

You'd still need to send the mlat messages from each receiver though, you can't aggregate them from one computer since there's no position included in the sent messages. And I don't know why it would be a problem to feed from each receiver, they need connectivity any way.

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