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Quantities and units. Electricity is a difficult substance to appreciate with the human senses. About the only way you get a feeling for it is to moisten the tongue and apply it between the terminals of a 9 volt battery. Of course, you get more idea if you are...

Semiconductors: Diodes & Transistors In the early days of electricity there were only two groups of material: insulators and conductors. Insulators are matters, which do not allow the flow of electric current through them. Glass, porcelain, dry air and dry wood...

FM stands for Frequency Modulation. It means that the RF-frequency will change according to the input audio signal. Example: A FM radio signal at 105.1MHz will not be exactly stable at 105.1MHz, The audio signal in the RF will modulate (change) the frequency for about...

Single Sideband Suppressed Carrier (SSB-SC): Single Sideband Suppressed Carrier (SSB-SC) modulation was the basis for all long distance telephone communications up until the last decade. It was called "L carrier." It consisted of groups of telephone conversations...

What is Single Side-band? Before you can understand what SSB is, you must understand how audio is transmitted via radio waves. The method by which audio is impressed on a radio signal is called modulation. The two types of modulation that most people are familiar with...

Quadrature Amplitude Modulation (QAM)- Brief Discussion I & Q modulation, A.K.A., QAM, is a method for sending two separate (and uniquely different) channels of information. As you know, the carrier is shifted to create two carriers: sin and cos versions. The two...

Modulation/Demodulation is a Nonlinear Process where Two Sinusoids are Multiplied (F1 x F2). The Product of this Multiplication--in the Time Domain--is a wave whose Amplitude is: a(X) = a(F1) X a(F2). However, in the Frequency Domain there is an Addition and...