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Product Name: Satellites to Deliver TV Direct to Home Viewers
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.
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.
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Height stowed |
12.6 ft (3.8 m) |
| Width stowed |
9.2 ft x 10.8 ft (2.8 m x 3.3 m) |
| Solar arrays deployed |
86 ft (26 m) |
| Antennas deployed |
23.3 ft (7.1 m) |
Weight
Beginning of life
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3800 lb (1727 kg) |
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.
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.
Company Details
Boeing is the world's leading aerospace company and the largest manufacturer
of commercial jetliners and military aircraft combined. Additionally, Boeing
designs and manufactures rotorcraft, electronic and defense systems, missiles,
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