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Product Name: DIRECTV
Product Description
High-powered satellites built by Hughes Space and Communications Company (HSC),
known today as Boeing Satellite Systems, Inc., began bringing true direct
broadcast satellite (DBS) service to homes throughout North America in 1994.
Stowed (left); In Orbit (right)
The spacecraft are 601 body-stabilized models ordered by DIRECTV,
Inc., a unit of Hughes Electronics Corporation. DIRECTV-2 and DIRECTV-3 are
collocated with DIRECTV-1 at 101 degrees West longitude and are used exclusively
by DIRECTV. Collectively the three satellites have the capacity to deliver more
than 200 channels of entertainment programming to subscribers that are equipped
with DSSTM digital home receiving units, which feature an 18-inch
dish.
To provide the high satellite power necessary for such small antennas, the
DIRECTV-1 spacecraft has 16 transponders powered by 120-watt traveling-wave tube
amplifiers (TWTAs). The TWTAs were reconfigured to provide eight channels with
240 watts of power on DIRECTV-2 and DIRECTV-3. The amplifiers are suitable for
analog or digital signals, and are capable of transmitting high-definition
television (HDTV) signals and compact disc-quality audio as well.
The satellites operate in the BSS portion of the Ku-band spectrum (12.2-12.7
GHz) and employ circular polarization. Depending on configuration of the
transponders, they can deliver 48 to 53 dBW radiated power over the contiguous
United States.
First DIRECTV satellite, in stowed configuration for testing
An Ariane 4 rocket carried DIRECTV-1 into space on Dec. 17, 1993. An Atlas IIA
rocket boosted DIRECTV-2 on Aug. 3, 1994. DIRECTV-3 was launched on June 9,
1995, on an Ariane rocket. The boosters take the spacecraft to geosynchronous
transfer orbit. The spacecraft's integral liquid apogee motor then raises it to
geostationary orbit 22,300 miles (36,000 km) above the equator. The
flight-proven bipropellant propulsion system includes not only the 110-lbf
Marquardt apogee motor, but also a dozen 5-lbf thrusters for stationkeeping
during each satellite's 12 years in orbit.
Each DIRECTV spacecraft measures 23.3 feet (7.1 meters) across with the two
transmit antennas deployed, and 86 feet (26 meters) long from the tip of one
four-panel solar array wing to the other. These arrays generate a combined 4300
watts of electrical power, backed up by a 32-cell nickel-hydrogen battery for
uninterrupted power during eclipse. The spacecraft weigh around 3800 pounds
(1727 kg) at beginning of life on orbit.
An innovative graphite antenna system makes its debut on the DIRECTV-1
spacecraft. The transmit and receive reflectors feature a specially contoured
surface that requires only one, rather than multiple, feedhorns to provide an
optimal signal. The composite material is so light that each 8-foot-diameter
transmit antenna weighs less than 20 pounds. The antennas are aligned in a
unified structure to provide a significant improvement in antenna pointing
performance.
The Hughes 601-now Boeing 601- satellite line was introduced by HSC in 1987 to
meet anticipated requirements for high-power, multiple-payload spacecraft for
such applications as direct broadcast, private business networks, and mobile
communications.
The Boeing 601 body is composed of two main modules. The bus module is the
primary structure that carries launch vehicle loads and contains the propulsion,
attitude control, and electrical power subsystems. The payload module is a
honeycomb structure that contains the payload electronics, telemetry, command
and ranging equipment, and the isothermal heat pipes. Reflectors, antenna feeds,
and solar arrays mount directly to the primary module, and antenna
configurations can be placed on three faces of the bus. Such a modular approach
allows work to proceed in parallel, thereby shortening the manufacturing
schedule and test time.
The operations control center for the DIRECTV satellites is in Long Beach,
Calif.; telemetry and command terminals are in Castle Rock, Colo., and Spring
Creek, N.Y. Uplink is from both the DIRECTV Castle Rock and Los Angeles
broadcast centers.
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