7-17 Comparison of MILSATCOM Systems
Introduction a. The chart below gives an overview of the characteristics of the principal UHF, SHF and EHF military satellite communications systems. The chart shows relative capabilities in terms of mobility, anti-jam, capacity and cost.
FLTSATCOM, AFSATCOM, LEASAT and UHF Follow-On b. FLTSATCOM, AFSATCOM, LEASAT and UHF Follow­On support tactical mobile forces. Strategic users will be shifted to Milstar. UHF has the advantage of low cost user terminals that can operate well with small, portable antennas. The capacity is relatively low, however it is adequate to support single channel voice circuits. UHF has a relatively low capability to resist jamming of the satellites.
DSCS c. DSCS supports command and control and high volume data transmissions. The capacity of SHF systems is quite high. The cost of the terminals and the satellites is higher than that for UHF but many of the systems have already been acquired, therefore future costs should be moderate. SHF systems resist jamming better than UHF systems. Mobility is decreased with DSCS because of the size of the user terminals and antennas, and the power needed to operate them. Army terminals are deployable but require more than one truck per terminal.
Milstar d. Milstar will support strategic level command and control and nuclear forces and provide added communications capability to tactical users. Cost of the satellites is high. A new family of user terminals is needed which will increase the overall cost of the system. Mobility will be enhanced because of the relatively small user terminals. The overall survivability of Milstar and its ability to effectively communicate even when jammed are much better than any of the other MILSATCOM systems. The designed capacity of the Block I satellites is relatively low. Changes in the Block II satellites will add more capacity. In addition, technological advances should increase the capabilities of EHF SATCOM systems.
7-18 International Military Satellite Communications Systems
Introduction a. In addition to US MILSATCOM satellites, the US military can use certain other MILSATCOM systems. Of course, permission must be obtained in advance.
SKYNET b. Skynet is a British military communications satellite system that was developed with US assistance. The first Skynet satellite was launched in 1969. Others were launched into geostationary orbit to complete the constellation. Their primary purpose is to provide military and government communication for Great Britain. Skynet IV has four X­Band channels with bandwidths from 60 to 135 MHz which are compatible with Army SHF DSCS terminals, two UHF FLTSATCOM compatible channels and one experimental 44 GHz EHF channel.
AN/FSQ-174 c. An AN/FSQ 174 control terminal will be installed at RAF Oakhanger, Great Britain for control of TACSAT terminals accessing the British SKYNET IV satellite.
NATO d. The NATO communication satellite program began in 1967 with the experimental use of two ground terminals communicating with a US satellite. The first NATO satellite was launched in 1970. NATO III is a spin stabilized satellite with a cylindrical body and a despun antenna platform on one end. NATO III has three communication channels in the SHF X­Band (compatible with DSCS terminals). The NATO IV­A satellite, launched in January 1991, is based on the Skynet IV design.
NATO Channels e. All channels are received through an earth coverage horn antenna which covers from the east coast of North America, across the Atlantic, all of Western Europe and the Mediterranean. Data is transmitted through either a wide coverage horn or a narrow beam antenna oriented only toward Western Europe. NATO also maintains an on orbit spare satellite to insure that communications can be provided continuously. There are about two dozen NATO ground terminals, most with 42­foot antennas.
AN/FSQ-173 f. AN/FSQ­173 control terminals were installed at Kester, Belgium and Folly Lake, Nova Scotia (Canada) for control of TACSAT terminals accessing NATO satellite.
7-19 Other Communications Satellites
Introduction a. In addition to the military communications satellites, there are others which are used by the Department of Defense.
Satellite Business System (SBS) b. The first Satellite Business Systems (SBS) satellite was launched in 1980. The commercial SBS provides integrated voice and data through dedicated digital communications networks. The satellites can also handle television broadcasts. The signals can only be received in the United States. DoD uses this system for high volume data transfer. The ground terminals are fixed stations. The military does not have tactical terminals that operate with this system.
TDRSS c. The Tracking and Data Relay Satellite System (TDRSS) is a key system in providing near continuous communications with the Shuttle without the reliance on the few ground stations. It is also used to relay data from low earth orbiting satellites such as LANDSAT. It is specifically designed to handle extremely high data rates of about 300 Megabits per second from a single source. TDRSS was the first system capable of operating simultaneously in three frequency bands: Two S­band transponders, twelve C­band transponders and two Ku­band transponders. It is capable of communicating with up to 26 different satellites simultaneously. There are currently four TDRSS satellites in orbit.

7-20 Commercial International Satellite - Communications Systems
Introduction a. Satellite systems are ideally suited for international communications. This is particularly true for third world nations which do not have a well developed communications infrastructure. Satellite communications provide a cost effective way to connect into the world communications system.
Intelsat b. Intelsat is the acronym for the International Telecommunication Satellites and is also the name for the international consortium formed in 1964 which is made up of communications agencies from each of the participating countries. There are more than 120 member nations providing service to more than 150 countries. In most foreign countries, the national government operates the telephone and telegraph services. The U.S. government formed COMSAT Corporation to operate the ground terminals in the U.S. and to represent U.S. interests.
Intelsat Early Bird c. The first Intelsat satellite, called Early Bird, was launched in 1965. Since then many Intelsat satellites have been launched into geostationary orbit to provide continuous, worldwide communications service. By 1992 there were about 1,000 ground stations transmitting and receiving through 19 Intelsat satellites. More than 65% of all international telephone trunk traffic and most of the international television traffic is carried over Intelsat. The system is designed to provide communications between fixed stations and does not support mobile users.

Intelsate VI d. Intelsat VI satellites are the latest type to be launched. Each Intelsat VI satellite has a capacity of 24,000 voice circuits and three television channels.
Intelsat service e. Intelsat provides the following categories of service:
  • International Telephony Service (which includes international telephone, data, telex and facsimile services).
  • International Television Services. Intelsat carries almost all intercontinental television service.
  • Intelsat Business Service (IBS).
  • Intelnet, a digital service designed for data collection and distribution using small, inexpensive micro-terminals and large central hub Earth stations.
  • VISTA Service, for domestic and international telecommunications services to rural and remote communities.
  • Domestic telecommunications services, which offers the purchase or long­term lease of Intelsat transponders to satisfy domestic communications requirements.
Intelsat Bands f. Intelsat satellites use the 6/4 GHz band (C­band) and 14/12 GHz band (Ku­band). (A 6/4 GHz band means a 6 GHz uplink frequency and a 4 GHz frequency downlink.)
Intelsat Ground Stations g. Intelsat ground stations are owned and operated by telecommunications organizations designated by their respective government.
DISA Use of Intelsat h. The Defense Information Systems Agency (IDISA) uses Intelsat to supplement its capabilities. Some Remote Tracking Stations of the Air Force Satellite Control Network (AFSCN) relay their data to the control centers over leased Intelsat circuits. During operation DESERT STORM, Intelsat provided approximately 25% of the communications capability external to the theater of operations. In addition, Intelsat provided direct telephone service between Saudi Arabia and the United States which allowed troops in the theater to call home.
7-20 Commercial International Satellite - Communications Systems, cont'd
INMARSAT i. In 1970 the Intergovernmental Maritime Consultative Organization (IMCO), an international organization, issued a statement of requirements for a satellite communications system. In 1975, IMCO formed the International Maritime Satellite Organization (INMARSAT), a not­for­profit consortium with representatives from 63 countries. Separate companies were formed in each of the participating countries. In 1982, INMARSAT took over the use of three MARISAT satellites and began service. Later, three MAREC satellites were added. Some newer INTELSAT satellites have INMARSAT transponder subsystems on them. A program called GAPFILLER involved the leasing of some channels on selected INMARSAT satellites in support of the U.S. Navy. There are nine L­band transponders on various satellites in geosynchronous orbit. These transponders provide two voice channels, one telegraph channel and one multichannel voice or 56 kbps data channel. INMARSAT terminals are common on most large commercial ships. The number of ground terminals is also expanding. The U.S. military used INMARSAT during Operations JUST CAUSE, DESERT STORM and RESTORE HOPE. Connectivity is provided through commercial phone systems to fixed sites or through portable INMARSAT terminals.
INMARSAT Terminals j. There are different INMARSAT terminals available from commercial manufacturers around the world. The type terminal used is dependent on the type of service desired and how it will be used.
INMARSAT-A INMARSAT­A Ship Earth Stations (SES) have been in use since 1982. Many commercial and military ships have these INMARSAT terminals. Through these it is possible to contact a ship anywhere in the world. There are now some transportable INMARSAT­A terminals that can be moved in two suitcase sized containers. Typically the antenna is 1 meter across or larger. The Army has approximately 120 INMARSAT­A terminals.
INMARSAT-B The INMARSAT­B terminal is an improved, digital version, of the IMARSAT­A terminal. The size and weight are similar to an INMARSAT­A terminal. Both ­A and ­B type terminals require that the antenna be pointing at the satellite. For mobile service a tracking antenna must be used. The INMARSAT­B terminal can provide 9600 bps facsimile and good quality voice service at 16 kbps.
INMARSAT-C An INMARSAT­C terminal can fit into one suitcase. The antenna is a hemispherical design which does not require accurate pointing and tracking. These small terminals provide text based services such as E­mail, telex and low rate data messages. As of February 1993, the Army had about 20 of these terminals.
INMARSAT-M The INMARSAT­M terminal is the newest type. It is meant to provide a capability that is more than an INMARSAT­C terminal but less than an INMARSAT­B terminal. The ­ M terminal provides a 4.8 kbps voice service and a facsimile rate of 2400 bps.
DESERT STORM Use of INMARSAT k. During Operation DESERT STORM there were more than 150 small INMARSAT terminals in use by the US and coalition military forces, the CNN news team in Baghdad, Kuwaiti resistance fighters, and others. INMARSAT terminals provide connectivity and compatibility between each of the U.S. military services, its allies and other agencies equipped with an INMARSAT terminal. INMARSAT terminals were also used successfully in Somalia.
7-21 Regional Satellite Communications Systems
Introduction a. In addition to the many satellite communications systems providing worldwide communications links, there are also satellite systems providing regional coverage to various parts of the world.
US Domestic Communications Satellites b. There are currently more than 25 satellites providing telecommunications service over North America. More than 50% of their capacity is used for video. About 18% of the capacity is used for telephone trunking, 15% for private data lines, 6% for government use and 4% is dedicated to private network users. The most common way to access these systems is over standard telephone lines to the operators' ground terminal. The Department of Defense uses some of these systems to support telephone and data communications within CONUS. Very Small Aperture Terminal (VSAT) technology is rapidly expanding the use of domestic COMSATS. These 3­foot wide antennas are providing more capability of communication through the satellite directly to the intended addressee without reliance on other ground stations.
Foreign Communications Satellites c. In addition to being members of Intelsat and/or INMARSAT, Russia, Japan, Germany, France, Great Britain, Australia, Italy, Spain, Mexico, Canada, China, Brazil, India, Indonesia and Thailand launched, purchased or leased satellites to meet their communication requirements. This gives these countries more control over the satellite and the traffic it carries.
7-22 Comparison of Military and Commercial SATCOM
Coverage and Orbits a. MILSATCOM has worldwide coverage because the satellites used are in a variety of orbits including geostationary, low Earth, polar and Molniya. Commercial SATCOM systems prefer using geostationary satellites because the satellites provide continuous coverage, the antennas do not need to track the satellite. Spot beam antennas on the satellites provide high gain but this narrows the coverage to specific geographical areas. In addition, virtually all governments have some form of control over the use of commercial telecommunications systems within their country. These factors have encouraged the development of regional coverage systems.
Terminals and Service b. In general, MILSATCOM users operate in a more demanding environment than civilian users, therefore MILSATCOM terminals must be more rugged. In addition, military users have a requirement to continue to operate under jamming conditions. The military requires a large number of compact, mobile terminals to support its mobile users who must independently communicate with the satellite. Civilian users with high data rate requirements generally gain access to the satellites through a central gateway facility which can have larger, fixed antennas. New technologies promise to increase the military's use of civilian SATCOM systems. Very small aperture antennas (VSAT) are enhancing civilian capabilities. VSATs are making civilian SATCOM systems more accessible and attractive to military users. Cellular telephone service is also an expanding field. Today, these systems are reliant on terrestrial central antennas. Service has been limited to metropolitan areas where there are enough subscribers to make the system profitable. There are proposals for a system of multiple satellites that would provide worldwide service similar to cellular telephones. The size of the civilian market for such mobile service is large and therefore it is expected that civilian requirements will drive the market. The military may be able to acquire non­developmental items (NDI) built to "best commercial practice" standards that would greatly enhance military communications.
Security c. Encryption of data, reduced probability of intercept and other security measures are mandatory for MILSATCOM systems. The military must use point of origin encryption when using commercial systems to handle sensitive data. For example, the STU III telephones used by the government provide good security when communicating over commercial phone systems that use satellites. MILSATCOM use of very narrow transmission beams, especially at EHF can provide a very low probability of intercept thus making the detection of ground transmitters more difficult.
Jamming d. The ability to continue to counter or compensate for jamming is highly desirable for military systems. At present this is not cost effective for commercial system operators. As technology advances it can be anticipated that commercial systems will implement some anti­jam capability to lessen susceptibility to inadvertent jamming caused by other systems. DSCS III provides some anti­jam capability and Milstar will provide considerably more.
Survive and Attack e. The ability to survive an attack on the satellites is desirable for MILSATCOM systems. Satellites can be degraded or disabled through a physical attack or by electromagnetic means such as nuclear burst, lasers, particle beams or other means. DoD has built some systems with hardened components and chosen certain orbital parameters to reduce the susceptibility of satellites to physical damage. Commercial systems do not have such protection. Of course, space is a hostile environment, therefore all satellites have some hardening of components to survive and be able to provide reliable communications.
7-23 MILSATCOM Request Procedures
JSC MOP a. All US military space assets are considered DoD/JCS assets, regardless of who developed the system or who operates it. As with any other critical resource with finite capabilities, procedures are necessary to insure that resources are allocated to those with the highest priorities and that the systems are not overloaded. In this way, space systems are available to the warfighting CINCs and subordinate commands from the military services. JCS Memorandum of Policy (MOP) Number 178, "Military Satellite Communications Systems" is the guiding document for MILSATCOM procedures. To manage requirements and resources, JCS established the MILSATCOM User Requirements Data Base (URDB) which evolved into the Integrated SATCOM Data Base (ISDB). It identifies requirements for MILSATCOM support based on JCS approved missions, provides operationally responsive MILSATCOM management and control for capacity allocation and adjudication, and ensures the effective and efficient use of MILSATCOM resources, based on operational priorities of mission requirements. The Defense Information Systems Agency maintains the ISDB for the JCS.
7-24 MILSATCOM System Managers
System Managers a. The MILSATCOM system managers include: Defense Information Systems Agency DSCS U.S. Navy FLTSAT/LEASAT/UHF Follow­On U.S. Air Force AFSATCOM Milstar
ISDB b. The MILSATCOM System Managers use the ISDB for the day­to­day management of their systems. They review requests for access to the MILSATCOM systems against the ISDB to ensure the requirements have been validated in accordance with JCS MOP 178 procedures. Requirements not validated are referred to the J6, JCS before access to the satellite can be granted. JCS is updating MOP 178 and will publish it as Chairman's Memorandum Policy 37.
MOP 178 Request Procedures c. The diagram below depicts MOP 178 request procedures to obtain MILSATCOM service. Normally, the command that establishes the Net Control Station or hub submits the request for service but any command may submit a request. For example, an Army corps typically establishes a MILSATCOM net using AN/TSC­85A and AN/TSC­93A terminals. The corps signal brigade prepares the request for service and submits it to the theater CINC. If the theater CINC concurs, the request is coordinated with the supporting Regional Space Support Center (RSSC). If other CINCs or federal agencies are listed in the connectivity diagram, then the request must be coordinated before the request is forwarded. For example, if a CINC wanted to establish a link to an embassy, then the request must be coordinated with the Department of State. Requests for MILSATCOM service that do not support CINC assigned operational missions are submitted through that service's channels with an information copy to the CINC of that area. Urgent requests may be submitted directly to the JCS (J6Z) with information copies to the Defense Information Systems Agency MILSATCOM Systems Office (DISA MSO) and the appropriate MILSATCOM System Manager. Routine requests are forwarded to the DISA MSO. The DISA MSO forwards a copy to the appropriate MILSATCOM System Manager who will complete a technical and operational assessment within six weeks. (MILSATCOM users with short term, one time, non­recurring requirements may be authorized access if the system manager determines that the requirement satisfies JCS MOP 178 criteria and if the request can be supported without adversely affecting other validated users.) For long term requests, the DISA MSO will develop a package for presentation of the request to the monthly meeting of the Joint MILSATCOM ISDB Panel. The panel is made up of representatives of each service and the JCS. They vote on whether the request is valid or not. The JCS makes the final decision to approve or disapprove the request. The JCS can approve urgent requests without validation if they support crisis, contingency, or wartime operational missions. If the request represents a validated requirement it is assigned a control number and added to the MILSATCOM ISDB.
7-25 Technology Applications in the 1990's
Introduction a. The capabilities and types of communications satellites continue to grow. New military domestic and international systems with enhanced or new capabilities will be introduced.
Direct Broadcast b. One of the largest new applications will be direct broadcast satellites with emphasis on television. Of course, cable companies and individual users have been able to receive television broadcasts for quite some time. The cost of the ground receivers and antennas is, however, quite high. New high power direct broadcast systems will only need small antennas and the converters are less expensive. Germany and Great Britain already have direct broadcast television satellites. Newer systems are expected to use a small, flat surface antenna, about 2 ft x 2 ft, that could be placed in a window or on a roof.
Mobile Communications c. The use of satellites to provide mobile communications to ships around the world is already well established. Mobile cellular telephones have expanded rapidly in recent years. The cellular technology is limited to in or near metropolitan areas where there are enough subscribers to make the investment profitable. A satellite based system could provide mobile telephone service to all areas, in fact worldwide. With such a service you could call from any place or receive phone calls anywhere without the originator even knowing where you are.
Signal Processors d. Improved signal processors on satellites will increase capacity in all frequency bands. Improved bandwidth compression techniques and multiple access methods will also result in increased capacity. Improved chip technologies will lead to smaller transceivers that require less power.
Antennas e. Improved antennas will provide more precise spot beams which lowers the power required and limits interference from other areas.
Inter-satellite Links f. Intersatellite links will provide direct connectivity between two or more satellites, thus eliminating the need for intermediate ground stations when sending traffic over long distances.
LIGHTSAT g. Lightweight, relatively inexpensive satellites are being developed to fill unique requirements or to fill gaps in existing systems. The Army has a significant number of UHF SATCOM transceivers but the satellites are heavily used by high priority traffic. The Army is very interested in the capabilities of lightsats which could be launched on demand to support specific operations.