Specific alternatives to this procedure will be described

Specific alternatives to this procedure will be described in Chapter 4.
The transmitted signal s(t) presented to the medium is subject to a number of
impairments, discussed in Chapter 2, before it reaches the receiver. Thus, the
received signal r(t) may differ to some degree from s(t). The receiver will attempt
to estimate the original s(t), based on r(t) and its knowledge of the medium, producing
a sequence of bits gl(t). These bits are sent to the output personal computer,
where they are briefly buffered in memory as a block of bits (g). In many cases, the
destination system will attempt to determine if an error has occurred and, if so, will
cooperate with the source system to eventually obtain a complete, error-free block
of data. These data are then presented to the user via an output device, such as a
printer or a screen. The message (m'), as viewed by the user, will usually be an exact
copy of the original message (m).