(U) Defense Satellite Communications System (DSCS) III

(The effects of any budget/program decisions made since the information was collected during 1997-98 are NOT reflected in the National Security Space Road Map (NSSRM).)

Overview: (U)
(U) SHF systems support worldwide secure-voice and high data-rate communications between the U.S. and its vast network of military installations and other government agencies operating on the ground and at sea. These systems are used for high priority communications such as warfighter support in the exchange of wartime information between defense officials and battlefield commanders and to transmit space operations and early warning data to various users. The backbone of SHF satellite communication systems is the Defense Satellite Communications System (DSCS).  Nine DSCS III satellites are on orbit including five primary and four reserve satellites.  The DSCS Service Life Enhancement Program (DSCS SLEP) provides performance enhancements for the last four DSCS III satellites.  These enhancements are designed to increase the DSCS tactical system capacity by over 200 percent. 

Description: (U)
(U) The DSCS III satellite was designed as an improved capability satellite to replace the aging DSCS II satellite constellation.  

(U) The first DSCS III satellite was launched in October 1982 along with a DSCS II satellite.  There are two communications sub-systems on the DSCS III satellite.  The primary system has eight antennas that can be connected in various ways to six independent transponders.  Each transponder has its own limiter, mixer, and transmitter so that it can be configured to serve a specific type of user requirement.  There are two earth coverage horns and one multibeam receiving antenna.  The multibeam receiving antenna (MBA) can be conformed to a variety of shapes, sizes, and locations by means of a beam-forming network that controls the amplitudes and phases of each of the 61 individual beams.  This antenna can also form "nulls" to counter jammers on the ground.  Two transmitters on the satellite are always connected to earth coverage antennas.  One antenna is a Gimballed Dish Antenna (GDA) which provides a 3-degree spot beam.  The other earth coverage antennas are two 19-beam transmit MBAs.  These antennas have the same capabilities as the receive MBA (except nulling).  

(U) The secondary communications sub-system consists of an AFSATCOM single channel transponder (SCT).  The SCT has its own UHF transmitting and receiving antennas that can be connected to the X-band Earth coverage or MBA receiving antennas.  The SCT demodulates the received uplink and remodulates it for transmission and can also store messages for repeated transmission.  The X-band uplink has anti-jamming protection. 

(U) The DSCS  terminal segment consists of approximately 635 fixed, transportable, and mobile terminals, and a control segment of five fixed DSCS Operations Control Centers. 

(U) DSCS satellite B13 was launched on an Atlas II booster from Vandenburg AFB, CA on 24 Oct 1997.

User Impact: (U)
(U) The Defense Satellite Communications System (DSCS) provides Super High Frequency (SHF) wideband and anti-jam satellite communications supporting critical national and strategic requirements for the National Command Authorities (NCA), ground mobile forces of all services, White House Communications Agency (WHCA), Navy, NATO, UK, and Diplomatic Telecommunications Service.

Programmatics: (U)
(U) Operational.
	(U) Termination: 01/2005 (2QFY2005).

Related Initiatives: (U)
(U) Adv Wideband Satellite (AWS), AFSATCOM, AN/WSC-6(V)X, Atlas, DDS, DISA STEP, DSCS II, DSCS Service Life Enhance Prog, Eastern Range, Lightwt Multi-band Sat Terminal, MIDAS, Single Channel Transponder Sys, STAR-T, Wideband Gapfiller

Related Requirements: (U)
(U) None.

Related Categories: (U)
(U) MILSATCOM, Satellite Operations, SHF Satellite Systems

Road Map Placements: (U)
(U) Major DoD Space Programs, MILSATCOM, National Security Space Road Map.

Lead Office: (U)
(U) Air Force.

Date of Information: (U)
01 February 1997

(The effects of any budget/program decisions made since the information was collected during 1997-98 are NOT reflected in the National Security Space Road Map (NSSRM).)