Monika Sharma

Assist. Prof. in GGI

Periodic Analog Signals

Periodic analog signals can be classified as simple or composite. A simple periodic analog signal, a sine wave, cannot be decomposed into simpler signals. A composite periodic analog signal is composed of multiple sine waves.

  • Sine Wave
  • Wavelength
  • Time and Frequency Domain
  • Composite Signals
  • Bandwidth
Sine Wave is the most fundamental form of a periodic signal.

Frequency and period are the inverse of each other.

f=1/T and T=1/f

Frequency
Frequency is the rate of change with respect to time.
Change in a short span of time means high frequency.
Change over a long span of  time means low frequency.
Phase
Phase describes the position of the waveform  relative to time 0.

Signals and Communication

A single-frequency sine wave is not useful in data communications.
We need to send a composite signal, a signal made of many simple sine waves.
According to Fourier analysis, any composite signal is a combination of simple sine waves with different frequencies, amplitudes, and phases.
Composite Signals and Periodicity
If the composite signal is periodic, the decomposition gives a series of signals with discrete frequencies.
If the composite signal is nonperiodic, the decomposition gives a combination of sine waves with continuous frequencies.
Bandwidth 
The bandwidth of a composite signal is the difference between the highest and the lowest frequencies contained in that signal.