ABSTRACT
Modulation is the process of impressing the source information onto a bandpass signal with a carrier
frequency f
. This bandpass signal is called the modulated signal s(t), and the baseband source signal is called
the modulating signal m(t). The modulated signal could be represented by
or, equivalently,
and
where o
¼ 2pf
. The complex envelope is
and g(t) is a function of the modulating signal m(t). That is,
Thus g[·] performs a mapping operation on m(t). The particular relationship that is chosen for g(t) in terms of
m(t) defines the type of modulation used.
