[单选题]The present INMARSAT system------ geostationary satellites positioned above the Atlantic Ocean.
[问答题]Basic description of DSC:DSC is basically a calling system. Each call consists of a “packer” of digitized information of one of four proirities:Distress, Urgency,Safety, Routine. Message can be routed to “all stations”,to an individual station or to agroup of stations ,using their Maritione Monile Selective-call Identify code (MMSI):Distressmessages are automatically broadcast to “All stations ”. In addition to the MMSI of source and destination stations,information can be conveyed in the DSC message:For example, to aid the Rescue Service,the DSC Distress alert message is configured to contain the following :A/ship’s identify(the nine digit MMSI) B/Time C/Nature of distress(in the form of standard code ) D/ship’s position.Where fitted ship’ officers should ensure. They are fully conversant with the procedure for entering the necessary information into DSC equipment:at sea,unless provide automatically from a navifation system, ship’s position should be update at least once during each watch period.
[单选题]On receipt of a relayed distress alert, ship in the area addressed should establish communication with the ____concerned to enable the assistance to be co-ordinated.
[单选题]COSPAS-SARSAT provides distress alters and location information to appropriate rescue authorities,____ for____in distress