Many of the sources such as TV, internet, mobile, radio, and many others are communication channels. The communication might be either in one-way or two-way and to establish communication there has to be some process. Like the transmitter transmits the signals through the communication medium and the receiver receives the signals.
Here, the communication medium is more crucial to make the signals stronger and transmit in the way that we desire. So, the strengthening of the signals can be done through modulation techniques.
So, the article describes the process of transmission of signals in PM. Derivation: PM is a type of angle modulation and it is defined as the change in phase of the carrier signal in correspondence with the amplitude of the message signal.
Here, both the frequency and amplitude of the carrier signal stays as constant whereas phase varies in accordance. The below figures clearly depict the definition of PM.
The resultant modulated wave has various points where the phase shift takes place. When there is a positive amplitude, the phase varies in one direction, while there is a negative amplitude, the phase varies in other directions. The basic waveform of a phase-modulated wave is as below. A radio signal including an oscillating carrier represents the basic sine wave.
The continuous amplitude of the sine wave which moves in negative and positive phases and returns to the original point after finishing one full cycle and it is the complete sine wave. Therefore as the input amplitude increases, the magnitude of the phase lead also goes on increasing from instant to instant. Increase in phase lead is equivalent to an increase in frequency. Similarly, as the input amplitude decreases, the magnitude of the phase lag also goes on increasing from instant to instant.
Increase in phase lag is equivalent to decrease frequency. Therefore phase modulation waveform will be similar to FM waveform in all aspects. Even though PM is used in analog transmissions , it is widely used as a digital type of modulation wherever it controls among dissimilar phases, which is known as PSK phase shift keying , and there are several forms are available in this. Some of the forms of FM that are used are listed below.
The above showed list is some of the forms of PM which are frequently used in the applications of radio. Thus, this is all about what is phase modulation , PM equation, a phase modulation graph. From the above information finally, we can conclude that PM is a type of modulation which denotes data as differences in the immediate phase of a carrier wave.
As a result the term angle modulation is often use to describe both. Phase modulation, PM is sometimes used for analogue transmission, but it has become the basis for modulation schemes used for carrying data.
Phase shoft keying, PSK is widely used for data communication. Phase modulation is also the basis of a form of modulation known as quadrature amplitude modulation, where both phase and amplitude are varied to provide additional capabilities. Before looking at phase modulation it is first necessary to look at phase itself. A radio frequency signal consists of an oscillating carrier in the form of a sine wave is the basis of the signal. The instantaneous amplitude follows this curve moving positive and then negative, returning to the start point after one complete cycle - it follows the curve of the sine wave.
The sine wave can also be represented by the movement of a point around a circle, the phase at any given point being the angle between the start point and the point on the waveform as shown.
Also the phase advances as time progresses so points on the waveform can be said to have a phase difference between them. Phase modulation works by modulating the phase of the signal, i.
This changes the phase of the signal from what it would have been if no modulation was applied. In other words the speed of rotation around the circle is modulated about the mean value.
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