Milstar is the satellite system that will provide survivable worldwide tactical and strategic communications for U.S. forces. Milstar is an entire system. The space assets provide a "communications switch in the sky." The ground assets provide user interface to the system command and control for the space assets. Milstar Flight-1 (FLT-1) is the first in a series of satellites that will populate the space network. This is a fully functional low-data-rate (LDR), ultrahigh-frequency (UHF), crosslink satellite. Hughes Space and Communications Company in El Segundo, Calif., is a member of the Milstar national team. Hughes provides the crosslink payload as a subcontractor to Lockheed Missiles and Space Company of Sunnyvale, Calif., and elements of the LDR payload as a subcontractor to TRW of Redondo Beach, Calif. The project is managed by the U.S. Air Force Space and Missile Systems Center. Major subcontractors for the Hughes effort are Frequency Electronics, Inc., of New York; Space Systems/Loral of California; and EMS of Georgia.

The Milstar system will provide uplink communications at extremely high frequency (EHF), 44 GHz, and ultra-high frequency (UHF), 300 MHz. Downlink communications will be at superhigh frequency (SHF), 20 GHz, and UHF, 250 MHz. It will provide trunk links between satellites using crosslinks operating at approximately 60 GHz.

Hughes provides five major elements for the LDR payload. They are the following:

Time and frequency reference subsystem -- Includes time-of-day clock for system timing and synchronization for spectrally pure frequency generation; and for dehopping of EHF uplink frequencies and hopping of SHF downlink frequencies.

SHF subsystem transmit equipment group -- Provides downlink modulation and power amplification at 20 GHz.

Synthesizer select switch -- Provides connectivity between wideband frequency synthesizers and EHF downconverters.

EHF downconverters -- Receives 44 GHz uplink, dehops it and downconverts to an intermediate frequency.

Antenna positioner equipment -- Includes beam steering mechanisms and control electronics for three shared-aperture EHF/SHF spot beam antennas. The pointing is accurate to 0.001 degrees.

Together these elements weigh 600 pounds and use 350 watts.

Hughes also provides the crosslink payload. The major elements are as follows:

Millimeter wave assembly -- Includes the antenna group with autotracking modulator, 60 GHz transmit and receive downconverter, and the telemetry/command unit. There are two assemblies, one on each satellite wing.

I Panel assembly -- Includes the receivers, acquisitions unit, autotrack unit and controls electronics unit.

Controls subsystem -- Includes the controls electronics on the I Panel and the two-axis mechanisms that interface the millimeter wave assemblies to the satellite wings.

Together this equipment weighs approximately 885 pounds and uses 280 watts.

Hughes provides integration, test and operation support through the life of the satellite after payload delivery to Lockheed. This includes test equipment and personnel located at Lockheed and test equipment and on-call support to TRW.