Why Satellite?
An Introduction to the Technology and Services
There are more than 800 satellites of all types in varying orbits around the earth including satellites used for:
- Communications & broadcasting
- Military & reconnaissance
- Weather
- Navigation & GPS
- Imaging & remote sensing
- Research
Communications & broadcasting satellites typically orbit above the equator at about 35,800 kilometers (22,300 miles) in what is called the “geostationary arc.” From this arc, the satellite appears to remain in a fixed location above the earth – a highly desirable feature that enables antennas on the ground to readily point to (or access) the satellite, and then receive or transmit communications signals.
The location of each satellite within the geostationary arc is referred to as its “orbital slot.” Because geostationary (GEO) satellites operate at a very high altitude above the equator, a single satellite can cover, or see, more than one-third of the earth. This makes GEO communications satellites extremely powerful for broadcasting content such as TV programs. One GEO satellite can cover continents (e.g., North & South America), and three can fully cover the earth (except for extreme northern and southern latitudes).
GEO satellites are often described by their orbital location, or slot, such as Telesat’s Anik F1 at 107.3 degrees West longitude. The orbital slot designations of “East” and “West” are in relation to the Prime Meridian that passes through Greenwich, London, United Kingdom.
There are more than 200 GEO communications and broadcasting satellites in orbit today around the world. Main frequencies are:
- C-band – Started satcom industry
- Uses 3.7 to 4.2 GHz to the receive terminal and requires larger dishes
- Supports video broadcasting (cable and over-the-air), and telecom trunking
- Mature in most markets with minimal use in Europe
- Ku-band – Wide use began in 1970s
- Across global regions, uses 10.95 – 11.2; 11.45 – 11.7; 11.7 - 12.2; and 12.25 – 12.75 GHz to the receive terminal and allows for smaller dishes
- Supports satellite Direct-to-Home (DTH) and VSAT networking
- Growing rapidly in most world regions; mature in North America and Europe