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3 Current and Programmed Satellite Communications Capabilities This chapter describes the panel's efforts to investigate current and planned satellite communications capabilities of the DOD, other agencies of the government, and allied countries and commercial organizations; determine if there are shortfalls in current and planned Navy capabilities; develop issues as a result of the shortfall investigations; evaluate potential new capabilities and technologies, particularly those in the commercial sector; and recommend promising technologies and programs to the Navy to support the power projection mission. The results of these investigations were viewed as input to the development of a naval communications architecture. This effort was chartered to look at a broad range of programs, capabilities, and technologies, and, therefore, the results extend beyond the boundaries of a goal architecture, which is necessarily constrained by resources and available technology. The effort, however, did not attempt to identify systems and technologies that were clearly unaffordable or that would not lead to reasonably high payoffs. Therefore, the panel concentrated its efforts on affordable, high-leverage, solution-oriented systems and enabling technologies that offer real and significant benefit to the Navy. The panel emphasized activities that offer improved capacity, capacity on demand, antijam, and/or low probability of exploitation communications when required by mission analyses. While the effort was fundamentally satellite-communications oriented, that panel has not neglected other approaches for LOS, extended-line-of-sight (ELOS), or BLOS communications. 3.1 BATTLE GROUP COMMUNICATIONS SYSTEMS A typical battle group communications scenario is depicted in Figure 3.1. An attempt has been made to illustrate the various communications links that can exist in support of a battle group. These communications must be able to support voice, record, data, and imagery, both intrabattle group and interbank group, as well as long-haul communications to land-based or remote facilities. The communications are carried over low-, medium-, or high-data-rate channels. The range of rates is defined by the requirements imposed by the missions to be supported. For example, a data link supporting radar imagery transmission can require data rates as high as 274 Mbps, whereas command and control links may require much lower data rates (i.e., <9.6 kbps). These rates may have to be sustained under peacetime, crisis, and conflict. It is the panel's opinion that Navy programs such as the ARC-210, Joint Tactical Information Distribution System (JTIDS), and the Common High Bandwidth Datalink (CHBDL) provide comprehensive capabilities for many intrabattle group line-of-sight or extended-line-of- sight communications. (Extended line of sight could require active relay platforms.) If sensor platforms are used, such as unmanned airborne vehicles (UAV), high-altitude long-endurance (HALE) unmanned and manned aircraft, it follows that these assets are also candidates for communications relay platforms that not only support the sensor data but can also be used for 22

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area communications defined by the altitude of the platform. The antiaircraft warfare (AAW) weapon support Data Distribution System being developed for the Aegis Cooperative Engagement Concept mission provides a robust and survivable data link for intrabattle group communications. It should be considered, along with other programs, as a means for providing high-capacity, protected communications for the battle group. DSCS SHF SATCOM FLTSAT/LEASAT ^ tcOp ff /ff X ' 5 OVERHEAD SENSOR ££ FIGURE 3.1 Battle group communications. There are several tactical communications research and development programs ongoing, particularly within the JTIDS program, that could lead to smaller, lighter, lower cost JTIDS implementations with significant capacity improvements. The U.S. Air Force is sponsoring these JTIDS activities. The panel reviewed selected ongoing Navy activities under Project Croesus and endorses the efforts of the Croesus study group1 with respect to tactical data link development. 'CNO, Director, Space and Electronic Warfare, "Tactical Data Link Assessment" briefing, June 15, 1992. 23

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3.2 SATELLITE COMMUNICATIONS SYSTEMS The panel investigated a wide variety of satellite systems to determine their applicability to Navy missions, particularly those missions involving precision strike, deep strike, and amphibious operations. The panel considered current and proposed satellite systems from the commercial, civil, and military sectors, as well as foreign and domestic systems. Satellite systems that employ low earth, geostationary, and highly elliptic orbits as well as high earth circular orbits were considered. The satellite systems considered by the panel are summarized in Table 3.1. TABLE 3.1 Satellite Communications Systems Considered UHF (FLTSAT, UFO) L-Band (INMARSAT, IRIDIUM. Global Star, Odyssey) C-Band (Commercial, INTELSAT, PANAMSAT) X-Band (U.S. and allied satellites) Ku-Band (Commercial, Orion, DBS, INTELSAT, TDRSS, TDRSS II) Ka-Band (ACTS, MILSTAR, EHF Payloads, Low cost EHF SATS, TDRSS II, IRIDIUM, Japan SAT, ITALSAT) Crosslinked satellites (MILSTAR, TDRSS II, FEWS, IRIDIUM, SYRACUSE II) New-generation LEO satellites/shuttle launched communications payloads Store and forward satellites ACTS - Advanced Communications Technology Satellite (NASA) DBS - Direct Broadcast Satellites The frequency range for these candidate systems is predominately UHF through EHF. For reference purposes, the current frequency band allocations used by satellite communications systems are provided in Figure 3.2. The effort did not treat laser communications via satellites, although it recognized that laser communications for satellite crosslinks is a viable option for future communication satellites, and the Advanced Research Projects Agency (ARPA) currently sponsors a low-cost, light-weight, crosslink laser program. 24

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|[H] MARITIME MOBILE ]F5]f L-BAND MIL UHF inn SHARED-MARITIME nn A T1-^ AERONAUTICAL L^1 1 Xrrn AERONAUTICAL rmA f LLEJ MOBILE LL5J T i i i i 200 300 400 1.50 1.55 1.60 1.65 MHz-*" GHz— >- 1.70 COMMEI CBAI ICIAL MIL (DSCS) COMMERCIAL JD X BAND Ku BAND ||500| ^ i 1 l 1 l i 1 i l l | 3 5 10 15 GHz->- MIL Ka BAND MIL Ka BAND | 1000 | i piooolA 1 l l l 1 l l l l 20 25 30 GHz-*- 35 MIL EHF CROSSLINKS VBAND 1 1 1 1 l l l 1 i i l i 42 45 50 GHz- 55 60 I XXXI REFERS TO BANDWIDTH ALLOCATION FIGURE 3.2 Current satellite communications frequency allocations. 3.2.1 Ultra-High-Frequency Systems The panel considered the existing UHF Fleet Satellite Communications System (FLTSATCOM) and its follow-on, the UHF Follow-On (UFO). FLTSATCOM has served the Navy well for many years in a wide range of tactical applications. The system provides connectivity between designated mobile users (ships, submarines, aircraft) and shore sites. The system provides global coverage between + 70 degrees latitude using geosynchronous satellites and supports a range of point-to-point as well as broadcast services. The FLTSAT EHF Package (FEP) is attached to two UHF FLTSATs to provide an early-on EHF communications capability to the operating forces and a test environment for the development of MILSTAR terminals. Each FLTSATCOM satellite provides relay communications on 23 separate UHF channels (ten 25-kHz channels, twelve 5-kHz channels, and one 500-kHz channel). The FEPs are compatible with selected MILSTAR EHF functions and have two antenna beams (5 degree 25

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spot beam and an Earth Coverage beam), providing a total of ten EHF low-data-rate (2.4 kbps each) channels.2 The UFO system will continue the Navy's UHF capability beginning in 1993 and will gradually introduce the added features of low-data-rate EHF channels and protected telemetry, tracking, and command (TT&C). The UFO UHF communications suite will also consist of 5- and 25-kHz channels, and on the fourth and subsequent spacecraft will include ten EHF channels for broadcast and communications purposes that are also MILSTAR compatible. The panel concluded that improvements can be made to Navy UHF communications systems by using more modern modems to increase frequency channel efficiency. The use of adaptive, nonlinear signal processing at ground stations should be evaluated as a means of providing a modest amount of electronic countercounter measures (ECCM) against a range of jammers or other types of interference. The panel highly recommends Improved Demand Assign Multiple Access (DAMA) techniques for the existing and proposed UHF satellites, and the consideration of retrofitting future UFOs to include medium-data-rate EHF channels. The panel also encourages the Navy to investigate the use of smart multiplexer terminals that allow for the more efficient use of available channel capacity on such links as FLTSATCOM and INMARSAT. These terminals are capable of combining data, voice, and low-rate video transmissions. 3.2.2 L-, C-, X-, and Ku-Band Systems The Navy currently has a vigorous program to install L-band terminals on selected ships that operate with the worldwide INMARSAT system. This program is applauded, and the panel encourages the Navy to continue the deployment of these terminals on surface ships as required. Like FLTSATCOM, the L-band INMARSAT channels can be improved in terms of capacity through the use of modern modulation techniques such as constant envelope, 8-phase, trellis- coded modulation. A simple test is in order to demonstrate this enhancement. The Navy has supported development work for such a modem that should be transparent to the WSC-3 UHF terminal. The panel encourages the continuation of this effort. The potential payoff would have significant impact on overall channel efficiency. Commercial geostationary satellites that offer services at C-band and Ku-band frequencies should be available to the Navy if commercial shipboard terminals are employed by the Navy. Commercial shipboard terminals exist with stabilization and can be readily demonstrated. Some work needs to be done to ensure full stabilization under the worst sea-state conditions. The panel anticipates that the size of these terminals can range from 1.2 meters (m) to 3.5 m for shipboard installation with stabilized platforms. Transmit power levels range from 30-W solid- state power amplifiers to 1- to 2-kW traveling wave tubes (TWTs) for C- and Ku-band applications. Typical high-reliability medium-power amplifiers using TWT technology are 2"Navy UHF Satellite Communications System, Description of," Naval Command, Control, and Ocean Surveillance Center, Research, Development Test and Evaluation Division Report FSCS-200-83-1, December 31, 1991. 26

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available at 50 to 250 W. A single TWT amplifier can now operate over the range from 6 GHz to 18 GHz at medium power levels. A typical listing of C-band and Ku-band satellites is shown in Tables 3.2 and 3.3. Because of the extensive geostationary orbit capabilities presented by these commercial satellites, the panel recommends that the Navy consider the acquisition of commercial satellite terminals that could be used in these frequency bands. The terminals could be bought or leased. The C- band commercial assets provide much better worldwide coverage than currently provided at Ku- band. However, Ku-band is steadily increasing in terms of on-orbit assets, and Ku-band satellites can be used for communications several hundred miles from the shoreline in many locations around the world. Of particular interest to the panel was the possibility of large amounts of on-orbit capacity at X-band, represented principally by the Defense Satellite Communications System (DSCS) II/III satellites, as well as selected future allied X-band satellites. DSCS provides the primary transmission path for much of DOD's highest priority communications. DSCS is designed to satisfy Worldwide Military Command and Control System (WMCCS) requirements and provides high availability service between the National Command Authority, the Joint Staff, unified and specified commands, service component commands, and organic combat forces, and among early warning sensor sites and command centers. Services provided include clear- and secure-voice, high-capacity digital data at an overall maximum throughput of 3 Mbps, and jam-protected circuits. The spacecraft uses six transponders with 10- or 40-W power output and employs multielement (61 and 19) receive and transmit arrays, respectively. Figure 3.3 summarizes DSCS capability and illustrates the channel and antenna configurations employed by various user communities. Table 3.4 summarizes strategic and tactical DSCS terminals available for military application. The panel anticipates that there will be a large X-band capacity on orbit in the 1995 to 2005 tune frame that could provide worldwide access to suitably equipped Navy platforms. U.S. industry is now able to demonstrate a shipboard X-band commercial terminal with a stabilized antenna in the 1.2- to 3.5-m aperture range and power levels that are consistent with C-band and Ku-band terminals. A summary of X-band satellites available from the United States and its allies is shown in Table 3.5. DSCS III can be considered the most capable of these X-band assets, with SYRACUSE and ITALSAT, NATO IV, and SKY NET representing lesser capabilities, and BRAZIL SAT, AUSSAT, and HISPA SAT representing satellites with only two X-band transponders for each satellite. The aggregate X-band capacity created by DSCS III and these allied satellites is significant. Also of interest is the Universal Antijam Modem (UAJM) under development by the Army's Communications and Electronics Command (CECOM) for all U.S. services. The UAJM has been released to our NATO allies. This frequency-hopped modem can be used to provide antijam/antiscintillation and interoperable channels over a wide variety of X-band satellites. It is recommended that the Navy consider X-band shipboard terminals equipped with the UAJM, or a low-cost equivalent available from industry, as a method for providing X-band service between U.S. and allied ships and Marine Corps terminals via a variety of X-band satellites. UAJM can also be used with C-band and Ku-band translating satellite transponders with prior access arrangements. 27

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TABLE 3.2 Typical On-Orbit Satellite Performance Capabilities ORBIT SLOT DESIGN LIFE ANTENNA COVERAGE EIRP. TRANSPONDERS @ BANDWIDTHS SATELLITE MANUF CUSTOMER dim C-Band PALAPA B2R Hughes Perumtel 113-E 1998 Indonesian and neighboring Asian countries 36 24 @ 36 MHz GALAXY V Hughes HCI 125°W 2004 CONUS, Alaska, Hawaii. Puerto Rico 36-37 24 @ 36 MHz SALCOM Cl GE RCA 137°W 2000 CONUS, Alaska, Hawaii 28-36 24 @ 36 MHz Americom ASIASAT-1 Hughes ASIASAT 105.5°E 2000 North Beam: China. Mongolia, Korea, Japan, Taiwan South Beam: Turkey through India and Phillipines 34-37 24 @ 36 MHz Kit-Band SBS6 Hughes HCI 99°W 2000 CONUS, Alaska, Hawaii 44-50 19 @ 43 MHz ASTRA IB GE SES 19.2°E 2001 Luxembourg and neighboring countries 45-52 16@ 26 MHz ECSJJF3 Aerospatiale Eutelsat 16°E 2000 Wide beam all around Europe 39-44 9® 36MHz Narrow beam around western Europe 47-52 7 @ 72 MHz TELE-X Aerospatiale Swedish Space 5°E 1997 Scandinavian countries 59-65 3 @ 27 MHz ' GSTAR4 GE GTE 125°W 2000 CONUS. Alaska, Hawaii 40 1 @ 40 MHz 1 @ 86 MHz 16 @ 54MHz East CONUS and west CONUS spot beams 42-45 SALCOM Ku-1 GE GE American 85°W 1996 CONUS or east CONUS and west CONUS 39^»8 37-43 16@ 54 MHz AUSSAT A3 Hughes AUSSAT 164°E 1997 National Australia 34-38 15@ 45 MHz Papua. New Guinea spot 41-45 SW Pacific Ocean region 29-34 Four Australia spot beams (W,C,NE,SE) 38-42 MARCOPOLO-1 Hughes BSB 31.3°W 1999 United Kingdom 59 5 @ 27 MHz JCSAT2 Hughes JCSAT 154°E 1999 Mainland Japan 49-51 32 @ 27 MHz Multiple Frequency INTELSAT VI F4 Hughes INTELSAT 27.5°W 2004 C-band: Hemi, zonal and global beams 26.5- 26 @ 72 MHz 12 ® 36 MHz 31 2 @41 MHz Ku-band: Steerable spot beams 51.7- 54.7 6@ 72 MHz 2 @ 77 MHz 2 @ 150 MHz 25 @ 33 MHz ARABSAT 1C Aerospatiale ARABSAT 31°E 1999 C-band: Arab States 31 25 @ 33 MHz S-band 41 1 @ 33 MHz 28

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TABLE 3.2 Continued SATELLITE MANUF CUSTOMER ORBIT SLOT DESIGN LIFE ANTENNA COVERAGE EIRP. dBW TRANSPONDERS @ BANDWIDTHS INMARSAT H F3 British Aerospace INMARSAT 178°E 2001 C/L-band: Atlantic Ocean Region L/C-band: Atlantic Ocean Region 24 39 1 @ 16 MHz 2 ® 4.5 MHz 1 @ 7.3MHz 1 @ 3.2MHz SUPERBIRD Bl Loral sec 162°E 2002 Ku-band : Mainland Japan 49-53 19 @ 36 MHz Ka-band: Mainland Japan 50-54 7 @ 100 MHz Ka-band: Tokyo spot beam 58-60 3 @ 100 MHz INS AT ID Loral India Space Research Org. 83°E 2000 C-band: India and neighboring countries 32 12 @ 36 MHz S-band: India and neighboring countries 42 2 @ 36 MHz SPACENET 4 GE ASC/GTE 101°W 2001 C-band: CONUS, Alaska. Hawaii Ku-band: CONUS 25-34 41 12 @ 36 MHz 6@ 72 MHz 6 @ 72 MHz PANAMSAT 1 GE PANAMSAT 45°W 1998 C-band: Latin and South America 34-42 44-48 12 @ 36 MHz 6@ 72MHz 6 @ 72 MHz Ku-band: Western and eastern Europe, CONUS except for Pacific time zone TELECOM D Fl Matra France Telecomm 8°W 2001 C-band: Semi-global beams and Antilles, Guyana, St. Pierre, Reunion spot beam 34-42 6 @ 50 MHz 4@ 92MHz Ku-band: Mainland France 50- 52.5 11 @ 36 MHz X-band: Global, center Europe, steerable spot 28-43 3 @ 40 MHz 1 @ 60 MHz 1 @ 80MHz CS-3B Loral NASDA 136"E 1995 C-band: Mainland Japan, outlying islands 31 2 @ 180 MHz Ka-band: Mainland Japan 38 10 @ 100 MHz ITALSAT Selenia JTALSAT 13.2-E 1993 Ka-band: Six spot beams over Italy 57 6 @ 147 MBPS demod/remod channels Ka-band: One spot beam over Italy 46 3@ 36MHz 3 Beacons: Western Europe spot beam-18.7, 39.6, 49.5 GHz 23-27 DPS KOPERNIKUS MBB Deutsche Bundespot 28.5°E 2000 Ku-band: Germany coverage 49 7 @ 44 MHz 3 @ 90MHz Ka-band 48 1 @ 90 MHz ANKE2 GE TELESAT 107.3°E 2003 C-band: Canada, northern half of CONUS, Alaska 35-37 24 @ 36 MHz Canada Ku-band: East and west Canada spot, Canada National, cross border beams 43-52 16 ® 54 MHz 29

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TABLE 3.3 Commercial Satellites to be Launched by 1994 SATELLITE MANUF CUSTOMER ORBIT SLOT LAUNCH DATE FREQ ANTENNA COVERAGE EIRP. dBW TRANSPONDERS ©BANDWIDTHS TURKSAT1B Aerospatiale Turkey's PSA 31°E 1993 Ku-band Turkey, Centra! Europe 48-51 10 @ 36 MHz 6@ 72MHz INTELSAT vn F2 Loral INTELSAT 177°E 1993 C-band One steerable, one global, two hemi, and four switchable zone beams 26-33 16 @ 72 MHz 8 @ 36MHz 2 @41 MHz Ku-band Three steerable spot beams 43-48 6 @ 72MHz 4 @ 112MHz INTELSAT-K GE INTELSAT 21.5«W 1992 Ku-band Western Europe, Latin and North America 50 16 @ 54 MHz TELSTAR 4A GE ATT 97°W 1993 C-band CONUS, Alaska, Hawaii, Puerto Rico, Virgin Islands 33-38 24 @ 36 MHz Aerospace Ku-band CONUS, Alaska. Hawaii. Puerto Rico. Virgin Islands 40-47 16 @ 54 MHz cross-straps avail. THAICOM 1 Hughes Shinawaira 101 °E 1993 C-band Taiwan, Pacific rim region 34 12 @ 36 MHz Ku-band Taiwan 50 3 @ 54 MHz USDBS 1 Hughes HCI 101°W 1993 Ku-band CONUS 48-54 16 @ 24 MHz or 8 @ 24 MHz GALAXY VH Hughes HO 91°W 1992 C-band CONUS, Alaska, Hawaii. Puerto Rico. Virgin Islands 38 24 @ 36 MHz Ku-band CONUS, switchable offshore coverage 45 16 @ 27 MHz or 8 @ 54 MHz SOUDARJDAD I Hughes Mexico Telecomm 109.2°W 1993 C-band Mexico, South America. Caribbean 40 12 @ 36 MHz 6 @ 72 MHz Ku-band Mexico, U.S. spot beams 47 16@ 54 MHz cross-strap with L-band L-band Mexico, surrounding waters 45 4@2MHz subbands, cross- strap w/Ku-band AUSSAT Bl Hughes AUSSAT 160°E 1992 Ku-band National Australia, five spot beams 44-51 15 @ 54 MHz cross-strap avail. 85°W 1996 L-band National Australia 46-48 1 @ 14 MHz cross-strap avail. Ka-band National Australia One beacon ASTRA 1C Hughes SES 19.2°E 1993 Ku-band Luxembourg and neighboring countries 52 18 © 26 MHz INSAT 2B ISRO India Space Depi 93.5°E 1993 C-band India 32 Unknown S-band 42 Unknown fflSPASAL 1 Matra Spain 31°W 1992 Ku-band Spain, Canary Islands. Americas 41-52 10 @ 36 MHz 4@ 54 MHz 4 @ 72 MHz X-band Unk 1 @ 40 MHz 30

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DSCS III CHANNEL AND ANTENNA CONFIGURATION RECEIVE ECCM NEACP NAVYC2 US-UK GMF WHCA CONTINGENCY JTP WIDEBAND AFSCF CSOC DDS DCS WIDEBAND AFSCF CSOC DDS DCS DTS UK DCS WIDEBAND WHCA WIDEBAND DCS SURTASS GMFAJ JCCS EAM TW/AA TACIES SURTASS TRANSMIT NORMAL CONNECTIVITY CAPABILITY All-service capability - WMMCCS/GMF Wideband — Service to isolated areas Operational flexibility — Operates with large/small terminals — Groups users by operational needs — Allocates transmitter power for maximum efficiency Six independent transponders (two 40-W channels, four 10-W channels) 61 element receive MBA Two 19 element transmit MB As FIGURE 3.3 Defense Satellite Communications Systems summary. 31

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TABLE 3.4 Defense Satellite Communications Systems Terminal Population G/T EIRP CAPACITY ANTENNA SEE NOMENCLATURE CAPABILITIES TYPE OCR for page 22
TABLE 3.5 SHF Satellite Communications Summary (X-Band Capabilities) There will be a large SHF satellite capability on orbit in 1995 to 2005 — DSCS II - DSCS III - DSCS III Upgrade - SKYNET - SYRACUSE — ITALSAT BRAZIL SAT - AUSSAT JAPAN SAT — HISPA SAT NATO IV Terminals of all kinds available Wide variety of modems available — Universal AJ modems available for nuclear-protected channels Allies will have abundance of SHF satellite capacity on orbit in 1995 to 2005 3.2.3 Ka-Band Systems The panel also reviewed satellite developments under way or projected in the Ka-band (EHF) frequency regime. MILSTAR is the preeminent military satellite communications development effort under way by the United States in this band, with low-data-rate channels available on the first three deployed MILSTAR satellites, followed by future MILSTARs with low and medium data rate capabilities. MILSTAR will provide a hard-core warfighting satellite communications capability with onboard processing to allow maximum flexibility by the user community, crosslinks for worldwide relay and control, and a variety of antenna configurations (spot, agile, and earth- coverage beams) to obtain maximum security and user flexibility and highly jam-resistant waveforms. The system is designed to provide full interoperability among service organizations. Figure 3.4 illustrates the planned MILSTAR configuration. Recent DOD reviews have modified the eventual constellation to include only low-inclined orbits. Figure 3.5 lists the EHF terminal procurements planned by each of the services. A significant number of terminals will be available to the services in the mid- to late nineties. 33

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.o -i—" 2 Ofl 1C O s S "8 CO ^ 2 D O 34

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TERMWAU, NOTE: MAJOR ACQUISITION IN 1998, $ NOT IN POM AIR FORCE TERMINALS SYSTEM DEPLOYMENT SHART-T SCAMP FYS nru FYM ms mt FTO rat ntt rnt nroi FYE nro nt« nros FYK SCAMP PBOR nrc rru nrw FYSS nr« nm nrw PI» PTOO nroi FYB nro FYM FYB FYK YEARS NAVY TERMINALS SYSTEM DEPLOYMENT CORE REQUIREMENTS 1541 TOTAL TERMINALS LDR: AIR FORCE • 104 COMMANDS • 305 LOW COST TERMINALS ARMY • 456 SCAMP NAVY • 343 NESP OTHER - 20 E-TSET LDR/MDR: ARMY •313SMART-T DEFERRED REQUIREMENTS 2650 TOTAL TERMINALS LDR: Ship PHOR PfS FYJJ FYM FYB FY« FY« PfM FY» FYOO FYfl Pf«2 FYW FYM FYOS PfOS YEARS • 2549 SCAMP BLOCK II • 55 NESP LDR/MDR: • 46 SMART-T FIGURE 3.5 MILSTAR terminals summary. The panel notes that ARPA is also sponsoring low-cost EHF experiments for low-, medium-, and high-data-rate capabilities. It recommends that the Navy foster and influence the ARPA activities, because the Navy has a large investment in EHF terminals, and there is great uncertainty about the future of the MILSTAR program. The Navy needs to have a fallback position at EHF if the MILSTAR capability is delayed. In addition to MILSTAR, the panel reviewed NASA's Advanced Communication Technology Satellite (ACTS), NASA's Tracking and Data Relay Satellite (TDRSS) I and II, JAPAN SAT or Superbird, and ITALSAT. The panel concludes'that, for the near future, the Navy should concentrate its efforts on EHF satellites at 44 and 20 GHz. The panel sees no reason for the Navy to be interested in ACTS at this time, since it is a CONUS-oriented 30/20- GHz single research and development satellite with an uncertain future. TDRSS, on the other hand, provides excellent Atlantic and Pacific Ocean coverage and could be used to support a number of Navy missions at Ku-band. The future of TDRSS II is uncertain at this time, but the TDRSS I program will likely continue. An assessment of selected geostationary satellites for Navy use is provided in Table 3.6. 35

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TABLE 3.6 Qualitative Assessment of Geostationary Satellites COVERAGE RATES ANTIJAM NUMBER OF SATELLITES FLTSAT* Worldwide LDR/MDR Low 4 ' UFO* Worldwide LDR/MDR Low 4 INMARSAT Worldwide LDR/MDR None 4 C-BAND Worldwide LDR/MDR Possible 4 X-BAND Worldwide LDR/MDR Good 6+ allies KU-BAND Regional LDR/MDR Possible Large number TDRSS Pacific and Atlantic Oceans LDR -» VHDR Possible*** 5 EHF** Worldwide (future) LDR, MDR (future) High Several * Poor polar coverage ** MILSTAR, FEP, UFO/EHF *** It is possible to use UAJM or lower cost commercial versions to provide AJ/LPI over C- and Ku-band links. Direct broadcast satellite (DBS) technology is developing rapidly, and this technology was reviewed for possible applications to the Navy. Hughes is developing a Ku-band DBS, and a number of direct broadcast technologies exist within the European satellite community. The Hughes effort consists of a satellite with a number of Ku-band transponders operating at 120 W per transponder with an 85-in.-aperture antenna used to transmit digital TV signals to the ground. The ground receiving facilities consist of small 18-in.-aperture antennas. With this arrangement, a number of digital multiplexed TV channels can be received. DBS technology could be applied to the battle group if the case could be made for using DBS techniques over the ocean. At the moment, DBSs are confined to populated areas and therefore restricted to landmasses. 3.2.4 Satellite Crosslinks Crosslinked satellites were also investigated by the panel. Satellites such as MILSTAR, TDRSS II, the Follow-on Early Warning System (FEWS), the French SYRACUSE III, and the commercial IRIDIUM low-earth-orbit constellation are typical of crosslinked satellites of the future. The characteristics of the crosslinks on MILSTAR are well known and are not discussed in this report. Regarding the TDRSS II, the crosslinks were expected to provide 300-Mbps service using 20-GHz technology. FEWS expects to provide crosslinks using either RF (Ka-band) or laser technology to support several Mbps. SYRACUSE III expects to achieve tens of Mbps on its crosslinks using radio frequency technologies. IRIDIUM will have crosslinks of 12.5 Mbps between adjacent satellites at 20-GHz frequencies. The IRIDIUM satellites will be an interconnected 66-satellite constellation for worldwide communications between handheld mobile subscribers at L-band. 36

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With respect to crosslinked satellites, the panel concludes that the Navy should concentrate its efforts on the use of MILSTAR at low and medium data rates. If TDRSS II materializes, then the Navy may wish to employ the TDRSS II crosslink via Ku-band shipboard terminals, but the uncertainty surrounding the TDRSS II makes such planning difficult. The panel advises the Navy not to consider TDRSS II as part of its medium-term options. FEWS, on the other hand, is scheduled to use the EHF MDR standards for its uplinks and downlinks at 44/20 GHz. Therefore, the Navy should consider FEWS as an option, given that the Navy will have deployed many EHF terminals by the time FEWS is operational. The Brilliant Eyes Program, part of the Space Defense Initiative, also involves a crosslinked satellite with 44/20-GHz uplinks and downlinks, respectively. However, support for Brilliant Eyes is not strong at this time, and the panel advises the Navy not to consider it as a communications satellite option. 3.2.5 Future Commercial Low-Earth-Orbit Systems Of particular interest to the Navy should be the future generations of low-earth-orbit satellites summarized in Table 3.7. These satellites tend to operate in the VHP-band for low- data-rate messaging or in the L-band and S-band for voice/data transmissions. Some set of low- earth-orbit satellite constellations will probably exist by the year 2000, and it is likely that this satellite capability will consist of one or perhaps two VHP data-only constellations, such as ORB COMM, and as many as two low-earth-orbit constellations for voice and data, represented by IRIDIUM, Odyssey, Global Star, or the results of INMARSAT Project 21, which is still under concept development. These potential low-earth-orbit satellite services should be viewed by the Navy as an alternate or complementary communications capability, when and where needed. These systems are being designed to provide secure voice telecommunications with existing encryption equipment (STU-III). Certain proposed constellations such as Odyssey and Global Star will use spread spectrum pseudo-noise (PN) modulation techniques for user uplinks and downlinks and C-band feeder links to interface with the public networks. With respect to store and forward satellites, solid-state technology will provide for several gigabytes of storage on a low-earth-orbit satellite, which can also forward the stored data to users at sea. These satellites can be equipped with uplink UHF capabilities for the protected insertion of data over friendly territories and UHF downlinks compatible with existing Navy receiving equipment on submarine and surface ships to bring about a store and forward capability for the Navy. The store and forward satellite could be used to transfer database information, imagery, weapons data updates, etc., at speeds of up to 10 Mbps. 37

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TABLE 3.7 Proposed LEO Mobile Satellite Communications Systems #OF ALT FREQUENCIES (MHz) TYPE OF SIGNAL SYSTEM COMPANY SATS ORBITS (km) SERVICES ARJES Constellation Communications Inc Herndon, VA 48 4 polar 1018 1610-1625.5 uplink 2483.5-2500 downlink; 5150-5216 down 6525-6541 up Position determination and reporting, two-way telephony, dispatch voice, facsimile, and data collection, distribution, and control services SS/CDMA ELLIPSO ELLIPSAT Washington. DC 24 3 highly elliptical 2903 by 426 1610-1626.5 up 2483. 5-2500 down Will connect to a cellular phone to convert 800-MHz cellular to the 2.5-/1.6-GHz RDSS bands SS/FDMA GLOBALSTAR Loral Cellular Systems Corp New York, NY 48 8 1389 1610-1626.5, 2483.5-2500, 5199-5216, 6525-6541. all bidirectional RDSS, voice, data communications SS/CDMA KIDIUM Motorola Inc Chandler. AZ 66 11 765 1610-1626.5 bidirectional; 27.5-30 up 18.8-20.2 down 22.5-23.5 crosslink between satellites Worldwide cellular telephony and portable phone service N.A. LEOSAT LEOSAT Inc Ouray, CO 18 3 1000 148-149 up 137-138 down Two-way communication and radio location for intelligent vehicle highway system N.A. ODYSSEY TRW Inc Redondo Beach, CA 12 3 inclined circular 10,370 1610-1626.5 up 2483.5-2500 down 19.700-20,000 down 29 ,500-30,000 up Voice, radio location, messaging, data services SS/CDMA ORBCOMM Orbital Communications Corp Fairfax, VA 20 3 inclined 2 polar 970 148-148.9 up 137-139,400.1 down Two-way communication and radio location; slow, low-cost data transmission N.A. STARNET STARSYS Inc Washington, DC 24 24 random 1300 148-149 up Global two-way communication, data, radio location Rule making for very high frequencies 137-138 down VTTASAT Volunteers in Technical Assistance (VTTA) Arlington, VA 2 single, circular 800 137.7 down 400.2 up; or 400.2 down 149.8 up Data services and file transfer primarily for developing nations N.A. CDMA = Code-Division Multiple Access FDMA = Frequency-Division Multiple Access RDSS = Radio Determination Satellite Service SS = Spread Spectrum N.A. = Not available 3.3 TECHNOLOGY OPPORTUNITIES Rapid advancements taking place in a number of technologies associated with telecommunications could greatly improve the Navy's ability to perform tactical missions. These technologies include microelectronics, antennas and transmitters, commercial worldwide 38

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telecommunication networks, communications security devices, multimedia technologies, and the ubiquitous use of GPS for network synchronization, network access, and network timing. Table 3.8 summarizes enabling technological opportunities that the panel has identified. TABLE 3.8 Enabling Technological Opportunities Microelectronics — Greater computing power — Smaller size — Lower power drain Antennas/Transmitters — Large satellite multibeam antennas — Conformal arrays for missiles and aircraft — Adaptive shipboard arrays — High-power transmitters for missiles and aircraft Civil and Commercial Telecommunications — Wideband worldwide networks — Worldwide personal voice/data connectivity — TV and audio broadcasts worldwide — Small, smart, cheap terminals — Large ratio data compression/imagery compression — Smart multiplexers Networks — Intelligent, adaptive nets — Embedded COMSEC and automated key management (over-the-air rckey) — Mass multi-user accommodation Use of Other DOD Systems — Ubiquitous GPS — Combined GPS/communications in handheld terminals 3.3.1 Microelectronics In the area of basic microelectronics, Table 3.9 summarizes the expected capabilities of dynamic and static random access memories (RAMs), processing speed, analog-to-digital conversion speed, and packaging associated with integrated circuits in the 1995 timeframe. These advances in microelectronics should provide the Navy with greater computing power, smaller size equipment, and in some cases, lower power equipment at lower cost. In addition to steady advances in microelectronics, antennas, which play a critical role in communications, appear to be moving toward multifrequency, multibeam configurations based on conformal, phased-array technologies that can be used on a variety of platforms, including ships, aircraft, and possibly missiles. Of particular interest is the ability of U.S. industry to develop and produce multifrequency antennas using stabilized parabolic reflector technology—an antenna that can be placed on board a ship. These antennas can operate at C-, X-, or Ku-band. Such an antenna aboard ship would provide for the serial use of available geostationary satellites at these three commonly used frequencies from a single parabolic antenna. Wideband feeds and 39

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wideband power amplifiers combine to make the multi-band stabilized parabolic antenna very attractive for shipboard use in the near term. TABLE 3.9 Advances in Integrated Circuits Dynamic RAMS 2 x 107 bits/IC by 1995 Static RAMS 3 x 10* bits/IC by 1995 Throughput/IC 108 ops/sec by 1995 Spaceborne processor 40 x 10' ops/sec by 1995 Analog-to-digital converters — 14-bit resolution at 10 mega samples/sec — 10-bit resolution at 100 mega samples/sec — 8-bit resolution at 500 mega samples/sec 40 giga ops in 125 in.3, 80 W by 1995 (ARPA) Advances in 1C technologies allow processing trades to be conducted On-board (space) processing, bandwidth compression, storage can be traded against communications link capacities (relay satellite vs. direct downlinks) and ground-based processing 3.3.2 Wideband Networks Worldwide telecommunications networks are under development by the U.S. intelligence community as well as the Defense Information Systems Agency (DISA). The so-called Joint Worldwide Intelligence Communication System (JWICS) is a Defense Intelligence Agency (DIA) network based on T-l link capacity (1.544 Mbps) that will eventually connect 100 locations around the world. JWICS could be used by the Navy to convey information to and from remote locations. The National Security Agency is developing an Integrated Services Digital Network (ISDN)-based network called the Global Telecommunications System to perform similar functions. ISDN-based systems should be of interest to future Navy telecommunications development efforts because these systems are designed to handle a variety of data traffic types, including interactive information services, electronic mail, digital voice, facsimile, file transfers, and wideband digital video services. Further, DISA is developing the Defense Integrated Systems Network based on commercial offerings of broadband ISDN. Advanced Research Projects Agency (ARPA) and Defense Development Research and Engineering (DDR&E) are pursuing a Global Grid telecommunications system based on fiber optics and ISDN standards. The Navy is therefore encouraged to take full advantage of these activities within the DOD and intelligence communities as well as commercial offerings leading to global wideband networks. These networks should provide the Navy with high-capacity connectivity to naval command centers and communications stations (or gateways to mobile forces) around the world. 40

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3.4 GENERAL ASSESSMENT OF NAVAL SATELLITE COMMUNICATIONS The Navy continues to be a major contributor to and user of tactical satellite communications. The outstanding performance of FLTSATCOM and LEASAT at UHF is well documented. These satellites support not only naval but also numerous joint command and control and intelligence missions. The performance of these UHF assets during Desert Storm, given existing throughput design limitations, was exemplary. The Navy will be using UHF satellites for years to come and is planning for a UHF Follow-On (UFO) satellite to FLTSATCOM. There are several thousand UHF terminals deployed at present to serve a variety of users, such as submarines, surface ships, aircraft, and fixed sites. The principal UHF satellite communications radio equipment for fixed sites and shipboard use is the WSC-3 transceiver and for aircraft, the ARC-210 transceiver. WSC-3 equipped platforms are considered the most capable and, in theory, should be able to support much higher data rates than currently employed in day-to-day operations over FLTSATCOM. Modern modulation and error-control coding techniques can support 48 kbps through the 25-kHz FLTSATCOM channels, thus realizing a sizable increase in capacity relative to current throughput rates. Likewise, modern access control techniques should provide a means to reconfigure and reallocate FLTSATCOM channels dynamically and rapidly, thus realizing a sizable increase in capacity relative to current throughput rates with increased user access. These techniques are referred to as multifrequency time division multiple access (MF TDMA) protocols. The combination of dynamic channel allocation and application of more modern modulation and coding could be used to realize a significant increase in FLTSATCOM channel efficiency and satellite throughput. At present, with the exception of the FLTSATCOM broadcast channel, the UHF satellites are vulnerable to enemy jamming or inadvertent interference. Thus, while UHF satellites were effective during Desert Storm, a more resourceful enemy could easily disrupt a large percentage of our UHF satellite communications. The Navy is taking steps to correct this problem with its investments in EHF satellite payloads (FEPs) and by placing EHF low-data-rate channels on the UFO satellite #4 and beyond. It would be highly desirable to have MDR channels on UFO in the future, and the panel advises the Navy to determine the feasibility of such a block change to UFO. EHF pay load technology has progressed significantly since the development of the current FEPs on FLTSATCOM, and a combination of LDR and MDR channels on UFO is recommended. The panel recommends that user terminal rates, which are often artificially restricted to 2.4 kbps, be increased to match the capacities technically achievable over UHF channels. INMARSAT, a worldwide system that continues to improve and evolve, is highly recommended to the Navy by the panel as a general-purpose peacetime satellite communications capability. The Navy is planning to install several hundred INMARSAT terminals, and it is recommended that the Navy examine the feasibility of achieving 56-kbps two-way communications over INMARSAT. The capability represented by INMARSAT is significant relative to its cost, and INMARSAT channel costs can be expected to drop to meet the competition from low-earth-orbit satellite systems of the future. 41

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The Navy is implementing the SMQ-11 antenna system at S-band to receive meteorological data from the improving DMSP satellite system. DMSP is planning for a store and forward capability from which the Navy could benefit, for example in forwarding databases from shore to the battle group. The SMQ-10 antennas that reside on carriers, two on each platform, are currently configured as S-band receive-only antennas. These 8-ft parabolic antennas are being replaced by the SMG-ll's phased arrays. The SMQ-10 space on the carriers could be used for improved communications. For example, the SMQ-lOs could be modified to provide dual S-band and X-band receive-only capabilities for the carriers. The X-band receive- only terminal (ROT) modification would allow for one-way medium-data-rate transmissions to the battle group over X-band satellites. The S-band ROT capability could be used to receive transmissions over classified assets. As an alternative strategy, the SMG-lOs could be replaced by 8-ft parabolics with two-way communications capabilities at X-band and perhaps C-band and Ku-band using a multiband stabilized parabolic antenna. Technology now provides for single- feed C-, X-, and Ku-band parabolics with single wideband power amplifiers covering the C-, X-, and Ku-band frequencies. Thus, the SMQ-10 locations on carriers could be used to provide new commercially available antennas for two-way communication. The panel advises the Navy to examine these options for near-term improved connectivity to the carriers. Antijam communications over these links could also be realized by using the UAJM. The Space and Naval Warfare Systems Command (SPAWAR) is considering a new program that would provide an integrated sub-intermediate frequency (IF) modular set of equipment for two-way communications over either UHF or SHF satellites. The equipment could be used to access X-band or UHF satellites using standard protocols, demand accessing, and data rates supported by these satellites. If SPAWAR continues with the integrated UHF/SHF program, it should reflect the latest results on multifrequency time division multiple accessing and modern modulation and coding schemes that provide for more efficient use of channel capacity. The Navy has not been a major satellite user at X-band, opting instead to invest heavily in EHF satellite payloads and EHF terminals. Recently, however, the Navy reexamined its place in the X-band satellite user community and has been actively testing and planning for increased participation. The Navy has an aggressive program in X-band demand assignment multiple access testing and is researching ways to achieve lower-cost X-band terminals for surface ships. Fortunately, low-cost commercial X-band terminals are available for surface ship deployment, and, as stated previously, these terminals can also be configured to operate at C- and Ku-bands with single feeds and single wideband power amplifiers. The Navy is the leader in EHF satellite communications. It has a vigorous "on schedule" and "on cost" terminal program and has invested heavily in EHF payloads for FLTSATCOM and UFO. The MILSTAR program has been approved for the first three satellites with low- data-rate channels and a fourth satellite with LDR and MDR capabilities. MILSTAR, on the other hand, is a very expensive satellite and will likely come under continued DOD and congressional pressure for curtailment and/or downsizing. The Navy, because of its leadership role and heavy investments in EHF, is advised by the panel to promote an EHF satellite fallback position within the communications satellite community. Technology in industry and the laboratories can provide for much lower-cost geostationary EHF satellite solutions. The ARPA Advanced Satellite Technology program is a possible avenue for this fallback position. The 42

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panel also advises the Navy to determine whether its EHF shipboard terminals can be easily upgraded to handle MDR transmissions if an MDR space capability becomes available. Also related to EHF, the Navy is contemplating a new towed buoy for SSN missions. The buoy will allow the submarine to remain at speed and depth while providing access to communications channels above the surface of the water. HF and UHF are likely candidates, but other frequencies could be examined, such as L-band over the IRIDIUM, Global Star, and Odyssey or VHP over ORB COMM, for use with the towed buoy. Some analysis suggests that a small EHF antenna could be placed on the buoy to communicate with EHF satellite assets. The towed buoy represents a resource for two-way communications for submarines. The communications options provided by this buoy should be identified for low-, medium- and high- earth-orbit satellites. 43