1545-1555 MHz
Inmarsat Aero
The satellite half of airline datalink: the same messages as ACARS, sent where there is no VHF ground station to hear.
Over an ocean or a desert an aircraft has no VHF station in range, so its datalink goes up to an Inmarsat satellite instead. Because the satellite is geostationary, the downlink is a fixed signal from a fixed direction, which makes it one of the easiest satellite receptions there is once you have a patch antenna and a low noise amplifier.
WaveShark reads the P channel signal units and the messages carried on them, at 600, 1200 and 10500 bit/s. The 10500 bit/s channels are the Aero-H and H+ downlink the long-haul fleet uses, and they are where most of the traffic is. Messages appear in the message view beside the VHF ones rather than in a tool of their own.
The satellite pointing window gives the azimuth and elevation to the satellite from your station and a level to peak on, so the patch can be aimed without a phone app.
What comes out
- Aircraft identity, where the message carries it
- The ACARS message and its label
- The signal unit type, on the P channel
$ waveshark --tune 1545.0 --messagesRead next
Something did not decode?
Record the burst with --record and open an issue with the capture. A capture that decodes becomes a test fixture.
Open an issue