Physical Layer


Fourier Analysis

The French mathematician J.B. Fourier proved that any reasonably behaved period function, g(t) with period T can be constructed as the sum of a number of sines and cosines:

\(g(t) = \frac{1}{2}c + \sum_{n=1}^{\infty} a_n \sin(2\pi n f t) + \sum_{n=1}^{\infty} b_n \cos(2\pi n f t)\) Where $f = \frac{1}{T}$ is the fundamental frequency, $a_n$ and $b_n$ are the sine and cosine amplitudes of the $n_{th}$ harmonics, and c is a constant.

Transmission Medium and Physical Layer

Transmission Medium and Physical Layer

Classes of Transmission Media

[!info]+ Transmission media

  • Guide wired
    • Twisted-pair cable
    • Coaxial cable
    • Fiber-optic
  • Unguided wireless
    • Free space

Classes of Transmission Media

Guided Transmission media

  • Guided media, which are those that provide a conduit from one device to another.
  • Include twisted-pair cable, coaxial cable, and fiberoptic cable.


  • A twisted pair consists of two insulated copper wires, typically about 1 mm think.
  • Twisted-pair