Real and Complex Signals:
A signal x(t) is a real signal if its value is a real number, and a signal x(t) is a complex
signal if its value is a complex number. A general complex signal x( t) is a function of the form
x ( t ) = x , ( t ) + i x 2 ( t )
where x,( t ) and x2( t ) are real signals and j = m.
Note that in Eq. t represents either a continuous or a discrete variable.