Communications has long been an essential element of warfare. One set of troops needs to know their battle plans and, ideally, what their opponents are planning by intercepting their communications signals. This essentially summarizes the requirements of defense-related radio designs: to provide secure communications that cannot be deciphered by an opponent. As technology grows in complexity, defense-related communications methods must provide an increased number of operating modes while also delivering improved reliability. As several articles in this issue detail, many major radio equipment suppliers are trying to achieve improvements in their products, with the goals of providing long-term reliable performance. In spite of popular opinion, they also seek to minimize equipment costs through the use of commercial-off-the-shelf (COTS) components whenever possible.

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Military planners have explored the use of many different communications technologies, including commercial cellular and wireless communications networks under certain conditions. Communications security is typically a function of the modulation and encryption technique, the frequency of operation (which may or may not be hindered by jammers), and the use of special transmission methods, such as frequency-hopping techniques. Designers of portable HF/VHF/UHF portable radios have done impressive work in reducing the size and weight of these systems while increasing their performance and durability. But they are still limited in range by such things as hilly terrain and they operate in frequency ranges where jammers are common.

One communications technology that provides many of the features needed by military users is satellite communications (satcom). This terrain-independent communications approach is used for national defense and homeland security applications, with a growing number of military users. Because the growth and expanse of commercial satcom systems far exceed the availability of satcom equipment for defense-related applications, military users often rely on commercial satcom systems. But military users are also well aware of the need for communications security, and are increasingly looking to equipment developers for portable, manpack systems and secure, compact ground terminals.

The U.S. Army has long been a user of commercial satcom services, but is looking to strengthen its own satcom capabilities through efforts on its 2020 satcom network. Equipment design involves flexibility and portability, including smaller satcom antenna dishes that can be easily mounted on military vehicles and lighter, more compact satcom radio packs that can be managed as part of a soldier’s backpack. Of course, frequency/wavelength has a bit to do with the size of the antenna, with larger satcom systems at UHF, and smaller antennas at higher X-, C-, Ku-, and Ka-band frequencies.

The U.S. Army has worked with other branches of the military through such efforts as the Warfighter Information Network Tactical (WIN-T) program and the Military Satellite Communications Systems Directorate (MILSATCOM) program to refine the design and performance of satcom equipment for secure military use. MILSATCOM includes military, government, and industrial partners devoted to strengthening satcom technology for mobile and fixed communications systems. For example, the U.S. National Security Agency (NSA), with its expertise in communications security, helps evaluate different satcom systems and equipment for their communications reliability and security.

Of course, the key limiting factor in the spread of satcom services has been the availability of orbiting satellites, and launching a new satellite is not something that can be done every day. But with the help of such organizations as NASA, satellite launches can be integrated into planned space exploration efforts, and the path can be cleared for increased satcom capabilities.

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