Satellite technology has made unprecedented success in military communication system. Military communication satellites are designed for surveillance and reconnaissance, and military satellites links communication center to front line operators. Reconnaissance satellites provide intelligence information on military activities of foreign countries.
There are basically three types of reconnaissance satellite including wide-band satellite, tactical satellite and protected satellite system. Wide-band satellite system provide point to point moderate to high data rate communication services. These satellites are used for making tactical satellite communication with small land mobile borne transmitting high power with small terminals. Protected satellites provide communication services to mobile users on land, aircraft vehicles.
Many satellites are not designated exclusively for military use but serve military functions. Satellites designed for remote sensing can have military uses also. Some commercial satellites even provide logistics support and command support for military units.
The commercial communications assets consist of constellations of geostationary earth orbit and low earth orbit satellites. These orbits are capable of operating with personal communication devices such as phones and low speed data transceivers, suitcase-sized terminals for larger bandwidth applications.
Commercial telecommunications companies maintain an inventory of commercial transportable Earth stations that can be deployed to enable the military to enable duplex communications links where terrestrial communication is not possible. The commercial earth stations range from 1.8 to 5.6 meters and possibly match the end user capacity requirements.
Mobile and Tactical Systems
The terminals associated with mobile and tactical military satellite communication systems are characterized with small antennas on ships, submarines, land vehicles, and aircraft. They also examine large transportable terminals, lightweight backpack and handheld terminals located on cruise missiles.
The first operational satellite of department of defense is the navy’s fleet satellite communications (FLTSATCOM) system, dedicated to tactical users. Air force acquired and launched the primarily UHF system being assisted by aerospace. Another tactical system, Leasat, was directed by Congress in 1976 to be a leased commercial service. By 1991, the Navy was operating six FLTSATCOMs and four Leasats, to save sustainment costs.
The UHF system continued UHF communications and aerospace supported the Navy throughout UFO’s development and deployment, providing mission assurance, analyzing communications, and designing a telemetry analysis workstation.
The next successor to UFO will be the Navy’s mobile user objective system that will provide enhanced access, quality, and communication for mobile users. The data rate of MUOS range from 75 bits/ sec to 64 kilobits/ sec in broadcast, point-to-point, and full duplex network topologies. Apart from this, the United Kingdom’s Skynet series and the NATO satellites are compatible with each other and with U.S. system waveforms.
Skynet is a British military communications satellite system launched in 1969. Others were launched into geostationary orbit to complete the constellation. It provides military and government communication for Great Britain. Skynet IV has four XBand channels with bandwidths from 60 to 135 MHz, two UHF FLTSATCOM compatible channels and one experimental 44 GHz EHF channel.
The NATO communication satellite launched in 1967 with two ground terminals communicating with a US satellite. NATO III is a spin stabilized satellite and has three communication channels in the SHF XBand. NATO maintains an on orbit spare satellite so that the communications can be provided continuously.
All NATO channels cover from the east coast of North America, across the Atlantic and Mediterranean. Data is transmitted by wide coverage horn or a narrow beam antenna. Most of the NATO ground terminals are 42 foot antenna and there are about two dozen NATO ground terminals.
In some part there was need to operate in contested environments, where users accept low to moderate data rates to provide protection against detection, interception, jamming and scintillation, and nuclear detonations.
Milstar supports strategic level command and control and provides added communications capability to tactical users. It was initially contracted in March 1982 and can operate independent of ground control and distribution networks because of its satellites to satellite links. Even in the presence of adverse conditions milstar’s system design showed strength in communication and has the flexibility to provide worldwide unscheduled connectivity.
The biggest advantage is that the mobility will be enhanced because of the relatively small user terminals. An AFSATCOM payload hosted on Milstar provides continuing AFSATCOM connectivity. Aerospace provided considerable performance analysis in development, fielding, and operational testing.
There are three segments in Milstar: Mission control, terminal, and space. The mission control segment controls Milstar satellites on orbit by performing satellite health maintenance, assesses system resource allocation, and communication management plans. The terminal segment includes fixed and ground mobile terminals, many types of terminals developed separately by the air force, navy, and army. The space segment consists of the cross-linked constellation of four satellites, ground terminals and users, and stations to control the satellites.
Military satellite communications has worldwide coverage and communication system is evolving and giving way to the next more-capable generation. MILSATCOM community has made good progress in developing new concepts.