Spacecraft Ties Distant Battlefields Into One Network
Orbital system offers flexible, secure data transmissions for ground, sea and air units.
The French military is enhancing its global communications capabilities with a new generation of dedicated satellites designed to simultaneously link several theaters of operation. The spacecraft features multiple antennas operating on different radio frequencies that can be aimed to provide highly focused, secure links to mobile and fixed groundstations.
As European Union (EU) military forces become increasingly involved in coalition combat and peacekeeping activities around the world, the need grows for jam-resistant, flexible connections between front line commanders and headquarters. By providing a system with a base technology that can be used for EU and NATO nations, France not only enhances its own national capabilities, but the continent’s as well.
Designed from the start as a dedicated military platform, the Syracuse III family of spacecraft will provide France with greater bandwidth and versatility than the existing Telecom 2 satellites, which serve dual military and civilian functions, explains Blaise Jaeger of Alcatel Space, Toulouse. A former vice president for military communications programs and now vice president of Alcatel Space’s marketing and sales division, Jaeger notes that Syracuse III began after BAE Systems dropped out of the Skynet program aimed at developing a multinational communications system for NATO. As a result, France chose to develop its own military spacecraft and awarded the contract to Alcatel in 2000.
Joining the existing fleet of Telecom 2 civil/military spacecraft, Syracuse III platforms will offer telephony, telegraphy and data transmission services conducted in either automatic or manual modes to link French military headquarters with land, sea and air units. The first satellite, Syracuse III A, is slated for launch in 2004. A second satellite will be launched in 2006, followed by an option for a third vehicle.
The French satellites most closely resemble U.S. wideband gap filler spacecraft in capability and mission requirements, Jaeger observes. For example, both types of craft transmit and receive in the X band. “It’s quite similar in terms of size and performance. Even if you look at some of the pictures of the satellites, they are quite comparable,” he says. But the Syracuse platforms are hardened against nuclear/electromagnetic radiation and possess an antijamming capability. The first three wideband gap filler satellites do not have these capabilities, although the next three will counter jamming, Jaeger explains.
Syracuse III satellites use multiple antennas to broadcast and receive data on the super high frequency (SHF) and extremely high frequency (EHF) bands. SHF systems include four spot beams, one global beam, one metropolitan France beam and nine 40-megahertz channels. EHF capabilities consist of two spot beams, one global beam and six 40-megahertz channels. The Syracuse III A satellite will be France’s first deployed EHF system.
The global and spot beams can be independently aimed to provide a variety of footprints for maximum coverage during operations. An extensive onboard routing capability built around digital processing systems allows the communications package to be reconfigured to meet optimal mission requirements. According to Jaeger, the satellite’s payload offers an enhanced data throughput up to several hundred megabits per second that can support multimedia services—a considerable advance over Syracuse II systems, he says.
Jaeger notes that processed EHF signals are very important for future mobile communications systems because they can create secure links with small groundstations. The French military’s long-term goal is to have more secure links with higher data rates—which EHF can provide, he maintains. A previous French Ministry of Defense EHF-capable satellite was lost in a launch accident.
Syracuse III A features an EHF-based secure link to groundstations in France. It also can switch between EHF and SHF to provide connectivity to mobile groundstations using SHF. With its multiple antennas, EHF transmissions can be received and beamed down in SHF or vice versa. Besides this cross-switching capability, the satellite also has extensive single-frequency functions. In the initial stages of operation, it will use its EHF links primarily to connect with France and the SHF transponders for links between itself and operational theaters. “The use of SHF allows us to use all the SHF bandwidth and all of the [satellite’s] nine SHF transponders for links with deployable stations,” he says.
This flexible communications arrangement also helps defend the platform against jamming. Syracuse III is the first satellite available with a protected SHF function, Jaeger claims. The spacecraft’s wideband and narrowband broadcasting capability can be modulated to meet the demands of its operational environment.
Another jam-resistant feature is an active receiving antenna coupled with a large onboard power reserve that allows signals to burn through jamming. The system was designed to resist countermeasures and operate in harsh electromagnetic conditions. Its onboard antijamming capacity works in conjunction with protected modems at fixed and mobile groundstations connected to the network. Both space and ground systems feature a secure communications link, permitting commands, data and telemetry to be transmitted and received under harsh jamming conditions.
The ground segment of the Syracuse III system consists of global management and security management centers operated by military personnel. The system offers im-proved service through upgraded Syracuse II ground and management segments that include Syracuse II deployable ground terminals, SHF anchor stations and EHF stations in France. Additional improvements include satellite control and system management centers. The basic system also is designed for expansion to meet French and allied nations’ requirements.
User terminal development will take place in the program’s second phase, Jaeger says. Developed jointly with Thales, the existing Syracuse II tactical terminals will be upgraded before new equipment and groundstations are developed, he says.
Alcatel also has entered Syracuse III in a NATO competition for military satellites to provide SHF, ultra high frequency and EHF communications. Jaeger notes that the firm submitted its bid this summer, and NATO will announce its choice early in the fall. The winner will provide NATO with a solution by 2005. Alcatel also is proposing an EHF capability for the alliance by 2008, he says. If Alcatel wins the bid, France and NATO will share Syracuse III A and B spacecraft as part of their strategic communications capabilities.