Lisäystaajuus

Lisäystaajuus, often translated as "additional frequency" or "side frequency" in English, refers to the frequencies that are generated when a signal is modulated. Modulation is a process used in telecommunications to encode information onto a carrier wave, typically by altering its amplitude, frequency, or phase.

When a carrier wave with a specific frequency is modulated by a signal containing one or more frequencies, new frequencies are created. These are the lisäystaajuudet. For example, in amplitude modulation (AM), if a carrier wave with frequency $f_c$ is modulated by a sinusoidal signal with frequency $f_m$, two side frequencies are generated: one at $f_c + f_m$ and another at $f_c - f_m$. These are known as the upper and lower sidebands, respectively.

In frequency modulation (FM) and phase modulation (PM), the situation is more complex, and the modulation process can generate an infinite number of side frequencies, although their amplitudes decrease rapidly as their distance from the carrier frequency increases. The bandwidth occupied by a modulated signal is determined by the carrier frequency and the frequencies present in the modulating signal, as well as the type of modulation used. Understanding lisäystaajuudet is crucial for designing efficient communication systems, allocating radio spectrum, and preventing interference between different signals.