# Amplitude modulation

## What is AM?

Amplitude Modulation is the done by modulating the Amplitude of an sinoid Carrier signal using the incoming signal.

The Carrier signal is a sinusoid with a fixed Frequency at least twice as high as the highest frequency occuring in the spectrum of the incoming signal. Usually a much higher frequency is choosen.

Amplitude Modulation schemes have been widely used in Analog Radio.

## Mathematical Setting

The output signal is the simple product of incoming signal and Carrier Signal with frequency *f*:

*output(t) = input(t) * sin(f * t)*

*TODO: it would be nice to type formulas in TeX, is this working in this wiki?*

*Sure. But some prerequisites has to be met. Perhaps ist easier to use pictures of the formula (the manual way of what the wiki does).*

## An Example

## Special Kinds of AM

- DSSC, Double Sideband Supressed Carrier
- SSB, Single Side Band
- Residual Sideband Modulation (modulation used for analog TV applications)
- QAM, Quadrature Amplitude Modulation

## Aquired Bandwidth

*it would be nice to have a picture showing how AM signals in the frequency spectrum behave and how much bandwidth they allocate. A short overview of AM-related problems would be nice, too. Has anybody of you this info handy?*

*what about noise sensitivity?*