Maritime distress radio call systems employing space-borne technology

Technical and operational requirements for a space-borne maritime alert system are considered and a brief survey of the presently proposed approaches and their basic parameters are reviewed. The main objective of the paper is to compare various system elements such as position determination, capacity for simultaneous alerts, multipath resistivity, alerting time, return link, coverage, link design, etc. in relation to the requirements. Emphasis is given to the examination of system elements with respect to geostationary and low orbiting systems. The experimental activities in the past and in the future are summarized.