Satellite television

Satellite television is television delivered by way of orbiting
communications satellites located 37,000 km (22,300 miles) above the earth's
surface. The first satellite television signal was relayed from Europe to
the Telstar satellite over North America in 1962. The first domestic North
American satellite to carry television was Canada's Anik 1, which was
launched in 1973.

Satellite television, like other communications relayed by satellite, starts
with a transmitting antenna located at an uplink facility. Uplink satellite
dishes are directed toward the satellite that its signals will be
transmitted to, and are very large, as much as 9 to 12 meters (30 to 40
feet) in diameter. The increased diameter results in more accurate
positioning and improved signal reception at the satellite. The signal is
transmitted to devices located on-board the satellite called transponders,
which retransmit the satellite signal back towards the Earth at a different frequency.

The satellite signal, quite weak after travelling through space, is
collected by a parabolic receiving dish, which reflects the weak signal to
the dish's focal point and is received, down-converted to a lower frequency
band and amplified by a device called a low-noise block downconverter, or
LNB (Direct broadcast satellite dishes use an LNBF, which integrates the
feedhorn with the LNB).

The signal, now amplified, travels to a satellite receiver box through
coaxial cable (RG-6 or RG-10; cannot be standard RG-59) and is converted by
a local oscillator to the L-Band range of frequencies (approximately).
Special on-board electronics in the receiver box help tune the signal and
then convert it to a frequency that a standard television can use.

There are two primary types of satellite television distribution: direct
broadcast satellite (DBS) and television receive-only (TVRO).

Direct broadcast satellite, or DBS, is a relatively recent development in
the world of television distribution. "Direct broadcast satellite" can
either refer to the communications satellites themselves that deliver DBS
service or the actual television service. DBS systems are commonly referred
to as "minidish" systems. DBS uses the upper portion of Ku-Band.

The first commercial DBS service, Sky Television, was launched in 1989 and
served customers in the United Kingdom. Hughes's DirecTV, the first
high-powered DBS system, went online in 1994 and was the first North
American DBS service. In 1996, Echostar's DISH Network went online in the
United States and has gone on to similar success as DirecTV's primary
competitor. Commercial DBS services are the primary competition to cable
television service.

In Canada, the two DBS services available are Bell Canada's ExpressVu and
StarChoice.

Television receive-only, or TVRO, refers to satellite television reception
equipment that is based primarily on open standards equipment. This
contrasts sharply with direct broadcast satellite, which is a completely
closed system that uses proprietary reception equipment. TVRO is often
referred to as "big dish" satellite television.

TVRO systems are designed to receive analog satellite signals from both
C-Band and Ku-Band satellite television or audio signals. TVRO systems tend
to use larger rather than smaller satellite dish antennas, since it is more
likely that the owner of a TVRO system would have a C-Band only setup rather
than a Ku-Band only setup. Additional receiver boxes allow for different
types of digital satellite signal reception, such as DVB/MPEG-2 and 4DTV.

Direct broadcasting satellites which can be received by what are known in
Chinese as little ears have had a major role in breaking the government
monopoly of information on Mainland China. Although met with frequent and
generally unsuccessful efforts to regulate them, satellite dishes are fairly
common in urban Chinese cities. Satellite television has also played an
important role in broadcasting to expatriate communities such as Arabs, and
overseas Chinese.