The additional burden the digitized transmission method will place on communications facilities is apparent
when the limitations of this technique are recognized. Each digitized voice channel will require a bandwidth of
at least 12 of the present standard 4-kHz telephone channels if voice recognition is required.
3. Additional factors affecting growth.
a. The growth in communications is not confined to the United States (US) military and commercial
systems. Other countries' systems are experiencing the same exponential growth of traffic. Both here and
abroad, new techniques are being developed to make more efficient use of the radio frequency (RF) spectrum,
particularly in the high frequency (F) range.
b. These worldwide demands are rapidly exhausting the number of available RFs in the usable RF
spectrum. This is the primary limiting factor in expansion of radio communication facilities. The limitations of
present systems and the need for an increase in potential capability in military communications systems make
the development and implementation of new systems a greater necessity.
LEARNING EVENT 2: REQUIREMENTS FOR A MILITARY COMMUNICATIONS SYSTEM
While many of the requirements to be met by future long-haul communications systems are the same for both
commercial and military use, there are, in general, more stringent criteria which must be met by systems for
military use.
The military is faced with the need to provide communications that will permit early warning of high-speed
attacks and absolute control of forces and weapons in conventional, limited, or operations other than war. To
meet these requirements, military long-haul communications systems must be oriented toward reliability,
invulnerability, security, flexibility, capacity, and quality. Commercial systems do not ordinarily require
invulnerability and security. These required attributes are discussed separately in the following paragraphs.
1. Reliability.
a. In order for a military communications system to fulfil its purpose, it must be highly reliable. The
reliability of a system depends on several interlocking factors-the reliability of the equipment and components
employed, the reliability of the particular communications media employed, and the skills and knowledge of the
personnel operating and maintaining the system. Each of these is important, for reliable equipment is useless
without skilled operating personnel, and skilled operating personnel cannot coax dependable performance from
poorly designed equipment.
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