Inmarsat Aero-P ACARS Multi-Channel Decoder

Inmarsat Aero-P includes an ACARS service for airlines to use while transiting the various ocean regions. This is much more reliable than HF ACARS. Inmarsat hosts 3-4 Aero-P control channels on L-Band for each ocean region. Each control channel is running OQPSK at 10.5K bits/s rate. This new decoder is actually 4 decoders in parallel and is capable of monitoring an entire ocean region. Currently both RFSpace SDR-IP and NetSDR is supported as well as the QSDR. The required bandwidth is 200 KHz. I can make this work with 190 KHz which would then add the SDR-IQ (with Ethernet server app) to the list of supported SDRs. As usual, this decoder interfaces over Ethernet. Below are a few screenshots of the working prototype.

Here is plot of the 4 channels from the IOR region. These are always on and continuous transmitting so they are easy to find.

IOR Aero-P Control Channels.

IOR Aero-P Control Channels.

The next screenshot is POR region. You can see the 3 Aero-P channels in the IQ Viewer in lower left. Above that are logging windows for each channel, in POR case, there are 3 channels. The other console window is the main decoder log, shows current SDR status, Signal Unit count, ACARS traffic count, CPDLC counts as well as log-on events. All traffic is sorted per aircraft and written to disk – so everything is archived.

POR Aero-P ACARS sample.

POR Aero-P ACARS Sample.

Here is a sample from UHF-Satcom for the AOR region (thanks Paul).

AOR region Aero-P ACARS sample.

AOR region Aero-P ACARS sample.

Here is a sample from another user monitoring IOR region.

IOR region Aero-P ACARS sample.

IOR region Aero-P ACARS sample.

There is support for streaming all TEXT ACARS messages over to Plane Plotter.

Aero-P ACARS on Plane Plotter.

Aero-P ACARS on Plan Plotter.

Below is screenshot of directory where messages are stored. You can see in this case there is some trouble with WIFI.

Sample logging.

Sample logging.

Support for ACARS Display was added, which is a step up from Plane Plotter IMO. You can see that ACARS Display will automatically look up the ICAO based on registration number.

ACARS Display Support.

ACARS Display Support.


If you click on one of the registration numbers (such as B-HKU) you will be brought to a website that will give you up to date information about that aircraft (as shown below).

Flight Lookup.

Flight Lookup.

Category(s): Inmarsat, Projects, SATCOM
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3 Responses to Inmarsat Aero-P ACARS Multi-Channel Decoder

  1. Great job ! I hope testing that one day !

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