Where does the imaginary part of a singnal come from? [duplicate]

1. What does the imaginary part of a signal mean?
2. What does the real and imaginary parts of the FFT signify?
3. What is real and imaginary signal?

What does the imaginary part of a signal mean?

Imaginary denotes a signal component that is in quadrature with (i.e. has a 90° phase shift from) the same reference signal. The reference signal can come from a local oscillator. (In DSP or SDR equipment the local oscillator might be a mathematical representation of one, rather than an analog circuit.)

What does the real and imaginary parts of the FFT signify?

The real portion of an FFT result is how much each frequency component resembles a cosine wave, the imaginary component, how much each component resembles a sine wave.

What is real and imaginary signal?

Real and Imaginary Signals

Example: If x(t)= 3 then x*(t)=3*=3 here x(t) is a real signal. If x(t)= 3j then x*(t)=3j* = -3j = -x(t) hence x(t) is a odd signal. Note: For a real signal, imaginary part should be zero. Similarly for an imaginary signal, real part should be zero.