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** Mazumder Alam**

Noise is an unwanted electrical or electromagnetic energy that degrades the quality of signals and data.Â Noise occurs in digital and analog systems, and can Â affectÂ communications system of all types. Noise is generated by random vibrations of conducting electrons and holes in the material. Noise is often referred to as thermal noise. Thermal noise is white and has a Gaussian amplitude distribution. In general, noise originating from outside the system is inversely proportional to the frequency, and directly proportional to the wavelength. All materials produce noise at a power level proportional to the physical temperature of the material.

An object emits White Gaussian Noise at a level proportional to its temperature, KTB.

Noise powerÂ **P=KTB**

K= Boltzmanâ€™s constant (1.3807*10^{-23} in J/K),

T=Temperature (in â°K), and

B=Bandwidth (in Hz)

Noise power is now in Watt. All Noisecom products are Additive White Gaussian type.Â Noise power can also be referenced to the Earthâ€™s noise floor, or â€“ 174 dBm/Hz. This value is referred to as ENR, or excess noise ratio. It is calculated by using the following formula:

Power Spectral Density,Â **PSD (dBm/Hz) = – 174 dBm/Hz + ENR**

**Additional Information:**

The following links provide the additional information on noise and Noisecom products: