Wireless Computing

Introduction to Wireless

Wireless Technologies


Network Security



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Interference Basics

Basics - Spread Spectrum - Error Correction - Inter-LAN

Interference is one of the most significant problems for wireless technology. Competing signals on the same frequency at the same time interact with each other in unpredictable ways, often garbling the original messages beyond repair. In digital terms, interference alters signals enough to cause misinterpretation of bits: 0's become 1's, or the other way around. Interference is a problem for wired mediums as well - two signals sent down a cable at the same time will interfere - but a wired LAN is a small, tightly controlled environment. There is no telling what else will be broadcasting on any given radio spectrum. Radio also has the problem of so-called background noise, both thermal and impulse. Thermal noise, primarily from the sun and other constant sources of radiation, is a relatively consistent background hum on most channels. Impulse noise (caused by lightning, sunspots, or other electrical devices) occurs in short, powerful spikes.

Radio emissions from Jupiter
Radio emissions from Jupiter - an example of thermal noise

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