This document discusses different types of noise that can interfere with radio transmitters and receivers. It describes noise as an unwanted signal that corrupts the original message signal. The document outlines several sources of internal noise like thermal noise and shot noise, which are produced by components in the receiver. It also discusses external noise sources such as industrial noise and atmospheric noise. The effects of noise are that it limits operating range and affects receiver sensitivity. The document provides detailed explanations of different internal noise types like thermal noise, shot noise, transit-time noise, and flicker noise.