These three defining properties are used to create three types of modulation: Amplitude: A high energy wave is characterized by a high amplitude; a low energy wave is characterized by a low amplitude. Amplitude modulation Amplitude modulation or AM is the method of varying the instantaneous amplitude of carrier signal accordingly with instantaneous amplitude of message signal.
Frequency: The frequency of a wave is the number of waves passing a point in a certain time. Frequency modulation FM or Frequency modulation is the process of varying the in instantaneous frequency of Carrier signal accordingly with instantaneous amplitude of message signal.
Phase: Phase is the position of a point in time an instant on a waveform cycle. Phase modulation PM or Phase modulation is the process of varying the instantaneous phase of Carrier signal accordingly with instantaneous amplitude of message signal.
Digital Modulation Digital modulation is similar analog except base band signal is of discrete amplitude level. The modulation scheme can be broken down in to three main types. Why is modulation used in telecommunication? There are many key problems in telecommunications that modulation helps to solve, including: Problem: Certain types of data such as voice, video, and bit streams from computers have lower frequency bands and therefore they cannot travel very far wirelessly because they cannot propagate through space.
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Market Segments 2. Pricing 5. Distribution Channels 6. Geographical Expansion. The importance of Encoding, Quantization, and Sampling in Pulse Code Modulation There are mainly 3 basic operations that are carried out in pulse code modulation. They are encoding, sampling and quantization. Before knowing about the importance of encoding, quantization and sampling process in pulse code modulation, let us know a short description of pulse code modulation.
It is a process in which a series of analog signals are converted into digital binary signals. This process is very useful in communication systems. A whole pulse code modulation technique consists of encoding, quantization and sampling process.
Therefore, these three operations encoding, quantization, and sampling play an important role in pulse code modulation. It is very important in pulse code modulation as large varieties of analog signals are transmitted in a digital communication system in. Everyone must be aware of the time value of money.
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Modulation makes it all possible, because it allows us to send voice and music which are essential baseband signals over a bandpass or "Broadband" channel. A sine wave at one frequency can be separated from a sine wave at another frequency or a cosine wave at the same frequency because the two signals are "orthogonal". There are other sets of signals, such that every signal in the set is orthogonal to every other signal in the set. A simple orthogonal set is time multiplexed division TDM -- only one transmitter is active at any one time.
Other more complicated sets of orthogonal waveforms—Walsh codes and various pseudo-noise codes such as Gold codes and maximum length sequences—are also used in some communication systems. The process of combining these waveforms with data signals is sometimes called "modulation", because it is so very similar to the way modulation combines sine waves with data signals.
From Wikibooks, open books for an open world. There is 1 pending change awaiting review. Communication Systems. It is because modulation is widely used in transmitting signals from one location to another with faster speed. Thus, the modulation technique has helped in enhancing wireless communication systems. Modulation and its types prevent the interference of the message signal from other signals. It is because a person sending a message signal through the phone cannot tell such signals apart.
As a result, they will interfere with each other. However, by using carrier signals having a high frequency, the mixing of the signals can be prevented. Thus, modulation ensures that the signals received by the receiver are entirely perfect. The signals within 20 Hz to 20 kHz frequency range can travel only a few distances.
To send the message signal, the length of the antenna should be a quarter wavelength of the used frequency. Thus, modulation is required to increase the frequency of the message signal and to enhance its strength to reach the receiver.
Length of the antenna can be easily calculated using this formula:.
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