WAFS data, provided by WAFC London via terrestrial 64 kilo bit per second (Kbps) lines, are uplinked from the hub at Whitehill to the INTELSAT 604 satellite located over the Indian Ocean at 60° E. Data are downlinked via a global beam to users in the AFI, EUR, MID and the western part of the ASIA region. The footprint stretches from eastern Atlantic, Cape Verde (20° W) to the central Australia (140° E).

This complimentary service, provided by WAFC Washington, uses satellites that cover the remainder of the globe to complete the ICAO AFS satellite broadcast global coverage. There are two ISCS satellite broadcasts, one covering the Atlantic, and one covering the Pacific. These overlap with SADIS to ensure worldwide availability of WAFS information and OPMET messages.

More about ISCS

Hub - VSAT (Very Small Aperture Terminal) is the hardware component of the system, supplied by Astrium. This consists of: a 2.4-metre parabolic antenna ('dish') and mount; and a low-noise amplifier/down converter, usually called a 'low-noise block' (LNB).

Receiver (one-way) - a receiver/demultiplexor that must be sited indoors with connecting cables.

• SADIS outputs use standard CCITT interfaces and protocols, and data are structured in accordance with WMO codes and formats
• Separate permanent virtual circuits are allocated for the different types of data
• Data will be output from a data port that complies with CCITT recommendations X.21 and V11
• Data throughput speed of 64 Kbps, protocol is X.25 (1988)

PC/workstation - this hardware decodes, archives and displays data received from the SADIS VSAT (a list of known workstation manufacturers is held at WAFC London and can be supplied on request).

• Designed to deliver the data to the end user in the 'open' industry standard X25 format
• Allows freedom to process these data in whatever manner is convenient to meet the user's requirement and/or communication system
• May be linked into the output port of the VSAT