MIL-DTL-24784/19B (SH)
c.
General approach to functional description. The general approach taken in preparing the
functional description shall be described in terms of objectives and method. The objectives
shall be to describe the weapons system in a manner suitable for progressive training and
support of the system troubleshooting procedures, and the text shall so state. The method of
presentation shall be to introduce all major system functions and physical interfaces in the
introduction section. Subsequent sections shall contain a description and analysis of major
system functions. The introduction shall inform the reader that each major function is
separately analyzed on at least two levels of progressively increased detail, as follows:
1.
The first level shall be a simplified description of the function supported by simplified
functional diagrams.
2.
The second level shall be a detailed description of the function supported by the SFDs.
Understanding of the simplified description shall be considered a prerequisite to
comprehension of the detailed description.
3.6.4.2 Major functional descriptions and analysis. Each major function shall be thoroughly
analyzed from generation to output on the basis of concurrent or sequential subfunctions such as
data and control functions. The analytic levels in order of increasing complexity are from
simplified to detailed. The detailed level shall be an expansion of, and correlate to, concepts
introduced at the simplified level. Each level shall be complete within itself. The selected levels
of presentation shall be adequate to indoctrinate the reader in weapon system technology to
ensure the training required for support of the PMS.
3.6.4.3 Simplified level of functional analysis. The objective of the simplified level shall be to
describe the major functions in terms understandable by a person possessing fundamental technical
knowledge, and thus provide this person with a basis for better understanding of the detailed
analysis. The simplified functional analysis shall explain the generation, transformation,
interrelation, and use of the data and control functions that constitute the major function. The
analysis shall cover essentials such as origin of the function at an equipment control or sensor;
transmission of the function via intermediate equipment such as switchboards, relay transmitters,
coordinate converters, and distribution boxes; and manifestation of the function at the terminal
equipment. Data and control functions essential to the development of a major function shall be
introduced and briefly described in terms of contributory purpose. Primary emphasis shall be
placed on the development of functional concepts in the geometrical reference frame provided by
NAVSEA OP 1700 or other official manuals. Only secondary consideration need be given to the
mechanization of functions. Functions involving computations may be explained in mathematical
terms, but at a level no higher than high school mathematics; that is, algebra, plane geometry, and
trigonometry (through sine, cosine and tangent). Explanations requiring advanced mathematics
higher than that expressed on a high school level shall not be presented. The simplified analysis
shall be supported by one or more simplified geometric diagrams, as appropriate, for the nature
and complexity of the function (see figures 19-7 and 19-8).
3.6.4.4 Detailed level of functional analysis. The objective of the detailed level shall be to
describe the major functions in terms directly related to the system troubleshooting procedures
and diagrams in the Fault-Isolation portion of the manual. Accordingly, a detailed functional
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