b. The requirements for reliability are much more stringent for a military system than for a comparable
commercial system. Even a brief failure of the military system might have disastrous international
consequences; and the military system is often forced to provide this reliability while operating in a much more
difficult environment than would ever be selected for commercial operation.
a. A second characteristic that distinguishes the military system from a commercial system is that it must
be as invulnerable to overt enemy action as possible. This overt action may take various forms, including
physical destruction or capture of parts of the system, or the jamming of the system operations by the
transmission of high-powered signals to blanket the system's frequencies.
b. To meet these requirements, the military system must be installed so it can be protected from enemy
attack and it must be designed to be as resistant to physical destruction as possible. The latter is often
accomplished through hardening of installation sites.
c. Protection against jamming attacks must also be included in the system. Antijamming equipment
generally requires larger bandwidths than those normally used in commercial practice, and is therefore
generally incompatible with commercial systems.
a. A third requirement placed on the military system is message security. Getting the message reliably
from point to point, in spite of overt enemy action, includes the ability to deny enemy access to the information.
b. To ensure the enemy is unable to decipher the information, elaborate encryption techniques are
necessary. The implementation of these techniques imposes additional requirements on the communications
system which would not normally be within the ability of the commercial communications systems to satisfy.
For example, one requirement imposed by the elaborate encryption techniques is an extremely accurate
a. Commercial communications systems grow in a fairly predictable pattern with the growth of the large
population centers. Military communications systems have no such directly predictable pattern. It is possible,
with the present world political situation, that requirements for reliable, invulnerable, secure communications
for military purposes may arise tomorrow in areas where no commercial system would, nor could, be
reasonably expected to supply such flexibility.