Figure 2-1 illustrates the equipment included in a
typical system to meet these communication
A SET consists of a unit or units and the
assemblies, subassemblies, and parts connected to
perform a specific function. Two examples are radio
receiving sets and radio transmitting sets.
A GROUP is a collection of units, assemblies,
subassemblies, and parts that (1) is a subdivision of a
set or system and (2) cannot perform a complete
operational function. A good example is an antenna
A UNIT is a combination of parts, subassemblies,
and assemblies mounted together that can normally
operate independently of other equipment. An
example of a unit is the power supply.
An ASSEMBLY is a combination of two or more
subassemblies joined to perform a specific function. A
SUBASSEMBLY consists of two or more parts that
form a portion of an assembly. It can be replaced as a
whole, but some of its parts can be replaced
The distinction between an assembly and a
subassembly is not always clear. An assembly maybe
considered a subassembly when it is part of a larger or
more complex assembly. A computer keyboard is a
good example. By itself, it is an assembly. However,
it is also a subassembly in a total computer system.
Another example you are very familiar with is a circuit
Figure 2-1.Communications system pictorial view.