Page 22 - Satellite Communications, Fourth Edition

2 Chapter One

weather conditions. Some of these remote sensing satellites also form
a vital link in search and rescue operations for downed aircraft and
the like.
A good overview of the role of satellites is given by Pritchard (1984)
and Brown (1981). To provide a general overview of satellite systems
here, three different types of applications are briefly described in this
chapter: (1) the largest international system, Intelsat, (2) the domestic
satellite system in the United States, Domsat, and (3) U.S. National
Oceanographic and Atmospheric Administration (NOAA) series of polar
orbiting satellites used for environmental monitoring and search and
rescue.

1.2 Frequency Allocations
for Satellite Services
Allocating frequencies to satellite services is a complicated process
which requires international coordination and planning. This is car-
ried out under the auspices of the International Telecommunication
Union (ITU).
To facilitate frequency planning, the world is divided into three
regions:

Region 1: Europe, Africa, what was formerly the Soviet Union, and
Mongolia
Region 2: North and South America and Greenland
Region 3: Asia (excluding region 1 areas), Australia, and the south-
west Pacific

Within these regions, frequency bands are allocated to various satel-
lite services, although a given service may be allocated different fre-
quency bands in different regions. Some of the services provided by
satellites are:
Fixed satellite service (FSS)
Broadcasting satellite service (BSS)
Mobile satellite services
Navigational satellite services
Meteorological satellite services

There are many subdivisions within these broad classifications;
for example, the FSS provides links for existing telephone networks
as well as for transmitting television signals to cable companies for
distribution over cable systems. Broadcasting satellite services are
intended mainly for direct broadcast to the home, sometimes referred