Distance Discrepancies

The ADS-B Receiver Project Graph shows that the most distant plane seen in the past 24 hours was at 229.6 km.

The FA Coverage Graph shows 8 between 240-320 km, and 2 at 400+ km.

Which one is correct?

FlightAware does statistic counting by UTC time and not the last 24 hours. You might need to compare the preceding or following day.

The polar graph uses the receiver’s lat and lon location set on your ADSB stats page. If your receiver’s location is off by a lot then the coverage graph will be also be off by the same amount.

Which one is correct?

If the decoder software is the same then it probably one of the above reasons. If the decoder is different then I think that it might be the decoder software.

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What do you mean by FA Coverage Map? The graph on the stats page shows numbers of messages, so maybe it is possible to receive messages that are not counted as a plane because of missing information? Maybe some messages are rejected

Or maybe a conversion error between km and nm somewhere? 229nm are roughly 420km?