A Generalized Model of Man Made Electrical Noise

Abstract

Many articles have been written and much work has been performed on the subject of man-made electri­ cal noise. Noise has been defined as "any inter­ ference or unwanted currents or voltage in an electri­ cal system or device".'This definition tends to be used by those who treat all received electrical energy as noise except for the desired signal. Most texts define noise as either thermal noise or impul­ sive noise. These texts 2,3,4 discuss the average power of thermal noise on a per unit bandwidth basis thereby assuming that the mean squared noise ampli­ tude is directly proportional to bandwidth. A few texts discuss the strength of impulsive noise assuming that the amplitude of impulsive noise is dir­ ectly proportional to bandwidth, (Reference 3). Military Standard 461, 462 and other government and industry standards utilize impulsive noise treatment of "noise amplitude directly proportional to band­ width" when measuring and reporting data in units of decibels relative to one microvolt per megahertz bandwidth. This noise amplitude relationship with bandwidth is simply expressed as, V 0 = kBx where v0 is the instantaneous voltage amplitude at the output of a circuit with 3 dB bandwidth B. When thermal noise is treated the exponent, x is equal to when impulsive noise is treated, x equals one, and k is the constant of proportionality.