Narrowband: Iridium Multi-Channel System (IMCS)
The main South Pole satellite systems, SPTR2 and GOES, provide approximately 9.5 hours of broadband connectivity each day. The Iridium Multi-Channel System (IMCS) was developed to provide an on/off continent data communications link to fill in the time period when the main communication satellites are not visible from the South Pole Station.
The main satellite systems transport any data or voice service that can be transmitted via the Information Technology (IT) network, and when they are unavailable, the IMCS automatically activates via the Iridium satellite network. Due to its narrow bandwidth, the IMCS is provisioned to carry only specific critical data, such as emails less than 100 KB, critical science and weather data, and other minor data services.
The IMCS uses a network router to bond 12 independent satellite voice circuits into a single data channel. This advanced technology delivers a gross throughput equivalent to a home user with a 28.8 Kbps dial-up modem. The IMCS uses more than 13.5 million satellite airtime minutes each year.