What is the key from the amplitude?

modulation is a process by which the properties of a specific radio signal, including phase, frequency or amplitude, change for data transfer. Some of the modulation types include key shifts, frequency keying, and phase shift keying. These types of modulations are part of the category called quantized radiodulation modes, which means that the regimes are generally used and defined as quantized points. The keying of the amplitude is the design of the old telegraph key and is used in digital modulation, where two amplitude of a certain support signal represent two values ​​that are binary. The amplitude of the signal changes, while the phases and frequencies remain constant and create signaling elements from variations of amplitude amplitude of the supporting signal.

Modulated signals in the keying of the amplitude shift are represented as turned on or off. Voice signals differ in voltage, and this applies to the carrier signals by means of amplitude modulation or amplitude shift. In communication digital signals,Two or more different levels of amplitude are represented in the process of modulation amplitude. Modulated progress are usually binary, consisting of two levels for switching on or off, which are represented as 1 or 0. Modulated progress of the supporting signal are sinusoid explosions, while quiet voice signals are modulated as flat lines.

At the transition points of the modulated signal, there are jagged discontinuities that lead to the bandwidth is unnecessarily wide. In digital communication, it is desirable that the modulated signals do not have any distortion, including overlapping and time propagation of individual phases. These distortion, known as intestinal interference, worsen the performance of the communication system error. This makes it difficult to reliably distinguish between changes in the status of the received signals. Achieving conditions where no intersymbol interference OCCURS is called the Nyquist ISI criterion.

NYQUIST ISI Criterium conditions can meet two different methods. One of these methods involves balancing or filtering the received signal. This will cancel the intestymbol interference, which is introduced in the reaction of the pulse channel.

Another method to achieve NYQUIST ISI criteria is to design impulses with limited band transfer to minimize and reduce the effects of ISI. When limiting the band, the jagged discontinuities are rounded; This can be used to a modulated signal or a transmitted digital message before transfer. Linearity is a factor that is important and the key from the amplitude can make it difficult for signal processing. The keying of the amplitude shifting does not have a constant envelope, while the key in terms of frequency shift and phase shift keying has one.