Modulation And Types Of Modulation Pdf
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- The Many Types of Radio Frequency Modulation
- Communication Systems/What is Modulation?
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The Many Types of Radio Frequency Modulation
A signal can be anything like a sound wave which comes out when you shout. This shout can be heard only up to a certain distance. A message carrying signal has to get transmitted over a distance and for it to establish a reliable communication, it needs to take the help of a high frequency signal which should not affect the original characteristics of the message signal.
The characteristics of the message signal, if changed, the message contained in it also alters. Hence it is a must to take care of the message signal. A high frequency signal can travel up to a longer distance, without getting affected by external disturbances.
We take the help of such high frequency signal which is called as a carrier signal to transmit our message signal.
Such a process is simply called as Modulation. Modulation is the process of changing the parameters of the carrier signal, in accordance with the instantaneous values of the modulating signal. The baseband signals are incompatible for direct transmission. The antenna used for transmission, had to be very large, if modulation was not introduced. The range of communication gets limited as the wave cannot travel to a distance without getting distorted.
The signal which contains a message to be transmitted, is called as a message signal. It is a baseband signal, which has to undergo the process of modulation, to get transmitted. Hence, it is also called as the modulating signal. The high frequency signal which has a certain phase, frequency, and amplitude but contains no information, is called a carrier signal. It is an empty signal. It is just used to carry the signal to the receiver after modulation.
The resultant signal after the process of modulation, is called as the modulated signal. This signal is a combination of the modulating signal and the carrier signal.
There are many types of modulations. Depending upon the modulation techniques used, they are classified as shown in the following figure. The types of modulations are broadly classified into continuous-wave modulation and pulse modulation. In the continuous-wave modulation, a high frequency sine wave is used as a carrier wave. This is further divided into amplitude and angle modulation.
If the amplitude of the high frequency carrier wave is varied in accordance with the instantaneous amplitude of the modulating signal, then such a technique is called as Amplitude Modulation. If the angle of the carrier wave is varied, in accordance with the instantaneous value of the modulating signal, then such a technique is called as Angle Modulation.
If the frequency of the carrier wave is varied, in accordance with the instantaneous value of the modulating signal, then such a technique is called as Frequency Modulation. If the phase of the high frequency carrier wave is varied in accordance with the instantaneous value of the modulating signal, then such a technique is called as Phase Modulation.
In Pulse modulation, a periodic sequence of rectangular pulses, is used as a carrier wave. This is further divided into analog and digital modulation. In digital modulation , the modulation technique used is Pulse Code Modulation PCM where the analog signal is converted into digital form of 1s and 0s. As the resultant is a coded pulse train, this is called as PCM. This is further developed as Delta Modulation DM , which will be discussed in subsequent chapters.
Hence, PCM is a technique where the analog signals are converted into a digital form. Principles of Communication - Modulation Advertisements. Previous Page. Next Page. Previous Page Print Page. Dashboard Logout.
Communication Systems/What is Modulation?
As we are living in an era of communication wherein we can easily transfer any form of information video, audio, and other data in the form of electrical signals to any other device or destined area. Although it is common in our perceptual experience that sending or receiving signals or data is simple, but it involves quite complex procedures, possibilities, and involved scenarios within the communication systems. So, in the scope of communication systems, modulation plays hold crucial responsibility in the communication system to encode information digitally in the analog world. It is very important to modulate the signals before sending them to the receiver section for larger distance transfer, accurate data transfer, and low-noise data reception. To be clear, let us dive into the detailed concept of knowing what is modulation, different types in it, and what are the types of modulation techniques used in communication systems.
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The term carrier is applied to the voltage whose characteristic is varied and the term modulating voltage signal is used for the voltage in accordance with which the variation is made. The modulation is the process of up shifting the message frequency to a range more useful for transmission. The carrier signal is a sine wave at the carrier frequency.
Modulation is the process by which information is encoded from a message source in order to optimize it for transmission. Frequency Modulation FM is the encoding of information in a carrier wave by changing the instantaneous frequency of the wave. FM technology is widely used in the fields of computing, telecommunications, and signal processing. Frequency Modulation is a modulation in which the frequency of the carrier wave is altered in accordance with the instantaneous amplitude of the modulating signal, keeping phase and amplitude constant. Modification of carrier wave frequency is performed for the purpose of sending data or information over small distances.
Modulation is the process of converting data into electrical signals optimized for transmission. Modulation techniques are roughly divided into four types: Analog modulation, Digital modulation, Pulse modulation , and Spread spectrum method. This method is divided into single carrier modulation, by which the carrier occupies the entire bandwidth i. In addition, there is a pulse modulation technique used to change the pulse width and spread spectrum method that spreads the signal energy over a wide band. In wireless communication, information is transmitted by encoding voice and data on radio waves of certain frequencies.
Modulation is the act of changing a signal to transmit useful data. There are three aspects of a signal that can be modulated; amplitude, frequency, and phase.
Advantages of Modulation
In electronics and telecommunications , modulation is the process of varying one or more properties of a periodic waveform , called the carrier signal , with a separate signal called the modulation signal that typically contains information to be transmitted. For example, the modulation signal might be an audio signal representing sound from a microphone , a video signal representing moving images from a video camera , or a digital signal representing a sequence of binary digits, a bitstream from a computer. The carrier is higher in frequency than the modulation signal. The purpose of modulation is to impress the information on the carrier wave, which is used to carry the information to another location. In radio communication the modulated carrier is transmitted through space as a radio wave to a radio receiver. Another purpose is to transmit multiple channels of information through a single communication medium, using frequency division multiplexing FDM.
For a signal to be transmitted to a distance, without the effect of any external interferences or noise addition and without getting faded away, it has to undergo a process called as Modulation. It improves the strength of the signal without disturbing the parameters of the original signal. A message carrying a signal has to get transmitted over a distance and for it to establish a reliable communication, it needs to take the help of a high frequency signal which should not affect the original characteristics of the message signal. The characteristics of the message signal, if changed, the message contained in it also alters. Hence, it is a must to take care of the message signal. A high frequency signal can travel up to a longer distance, without getting affected by external disturbances.
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И они еще решили оставить меня здесь на ночь.
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