Principles of Communication Systems, Third Edition

Herbert Taub, Donald L Schilling, Goutam Saha

Course : Digital Communications

Topic : Mathematical Representationof Noise

1

Department of ECE

Raghu Institute of Technology

Sources of Noise

• Thermal Noise

• Shot Noise

• Additive Noise

• Multiplicative Noise (fading)

• Gaussian Noise

Noise: Frequency Domain Representation

Noise : Power Spectrum

Noise Represetation

Filtering Gaussian Noise

Noise : Spectral Component

Noise : Narrowband Filter Response

Noise PSD : Effect of Filter

Mixing Noise with Sinusoid

Mixing Noise with Noise

Linear Filtering of Noise

Noise and Low Pass Filter

RC Low Pass Filter:

Ideal Low Pass Filter:

Noise and Band Pass Filter

Noise and Differentiator

A differentiator follows

Noise and Integrator-1

An integrator follows

Noise and Integrator-2

Quadrature Components of Noise

It is sometimes more advantageous to represent Narrowband noise centred around f0 as

Now,

PSD of Quadrature Components

Probability Density of Quadrature Components and Time Derivatives

Noise : Orthonormal Coordinates

Irrelevant Noise Components and Optimum Receiver

End of Chapter 7