Measurement and Control

Twenty-five years of experience has proven the high reliability of satellite communications. The creation of the International Maritime Satellite Organisation in 1979 opened the way for development of small satellite terminals for use by individual users. The recent order for a new generation of satellites to serve the needs of this 45-nation co-operative and development of the Standard-C system will enable it to provide a message/data service to small and low cost terminals by 1988. Standard-C will create new opportunities to remotely monitor and control processes regardless of distances from a central operations centre. It will permit those on duty to receive routine reports automatically at fixed intervals and/or when measurements fall outside pre-set limits. In the event of an abnormal situation developing it would be possible for the controller to interrogate the sensors at the site by ‘polling’ at any desired interval. This would enable a process to be continuously monitored and devices or systems remotely controlled as required. Because the satellites provide global coverage vast areas can be monitored and controlled independent of local telephone or microwave links. This may be particularly important in areas where individual sensor sites and their links may be vulnerable to disruption due to the possibility of flooding, landslides, earthquakes, etc. In addition, such a system could be used to control day to day operations of sluice gates, etc. in remote areas and thereby lead to improved water management techniques.