Decoding Immarsat geostationary satellite text messages

A nice hack has been published on how to decode satellite-based text messages (STD-C EGC) of an Immarsat geosat. Those messages include information about search and rescue, coast guard, weather and much more. The hack consists of a tutorial on how to build a cheap antenna out of a modified GPS or helix antenna and how to pipe the outputs into SDR# and then to display messages with a program called tdma-demo.exe, which despreads the messages from the time division coding. Also have a look here.