c. Laying wideband cables over long distances is a long-term project and, once in place, the cable systems
are relatively inflexible. Cables laid "over land" are generally buried. Even when property acquisition is not
considered, this is a long involved operation. The laying of an intercontinental undersea cable may require 5
years or more, including the design and manufacture of the cable itself.
d. From a military standpoint, the greatest weakness of long-distance cables is their vulnerability. A cable
system offers an infinite number of points at which it may be attacked or sabotaged. An overland cable may be
made fairly survivable if buried deeply enough. An undersea cable can easily be cut by either surface ship or
submarine.
LEARNING EVENT 4: ADVANTAGES OF SATELLITE COMMUNICATIONS
It is apparent that new techniques and equipment are needed to overcome the present limitations of our military
communications systems. The military department has long recognized the potential advantages of using
satellites and have conducted research and development programs for a number of years. These programs are
designed to produce a practical military satellite communications system which will incorporate all of the
features required by the military. Additionally, communications systems employing satellite links offer a
unique combination of advantages for long-distance trunking.
1. Capacity. Eventually satellite systems will be capable of handling hundreds of voice frequency (VF)
channels, although the first-generation satellite systems were at first limited to approximately four VF channels.
2. Reliability. The reliability of active satellite communications systems will be limited mostly by the
reliability of the equipment employed and the skill of the operating and maintenance personnel.
3. Invulnerability.
a. While it is possible to destroy an orbiting satellite by rocket fire, the present developments in rocketry
suggest that this would be quite difficult. It would be particularly difficult to destroy an entire system
employing random orbit satellites, primarily because of the number involved.
b. The present state-of-the-art indicates that satellite communications ground stations in certain instances
will be vulnerable to jamming attacks. However, by judicious planning and systems design, the enemy could be
forced to expend so much time, effort, and equipment to effectively jam our communications facilities that the
attempt would be unwarranted from his point of view.
c. A rocket or satellite-based jammer with limited power must be positioned within the main beam of the
ground station to be effective. This implies that the rocket or satellite jammer must be in approximately the
same position and orbit as the communications satellite. Considerable effort on the part of the enemy would be
required to achieve the precision of position necessary to establish such an orbit.
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