Multiplexor

5 Key excerpts on "Multiplexor"

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  eBook - PDF

  Multiplexing

  • Somayeh Mohammady(Author)
  • 2019(Publication Date)
  • IntechOpen

    (Publisher)

  7 Section 2 Multiplexing Basics 9 Chapter 2 Multiplexing Vijayakumar Nandalal and M.S. Sumalatha Abstract In any communication system that is either digital or analog, we need a com-munication channel for transmission. This channel can be a wired or a wireless link. It is not practical to allocate individual channels for each user. Therefore a group of signals are combined together and sent over a common channel. For this we use multiplexers. A multiplexer is a device that allows digital information from several sources to be routed onto a single line for transmission to a single destination. A demultiplexer does the reverse operation of multiplexing. It takes digital informa-tion from a single line and distributes it to a given number of output lines. Keywords: frequency division multiplexing, time division multiplexing, code division multiplexing, wave length division multiplexing, orthogonal frequency division multiplexing, amplitude shift keying, frequency shift keying, phase shift keying 1. Introduction Multiplexing is the process of transmission of information from more than one source into a single signal over a shared medium. We can be able to multiplex analog or digital signal. If analog signals are multiplexed, then this type of multiplexer is called analog multiplexer. If digital signals are multiplexed, then this type of multiplexer is called digital multiplexer. The advantage of multiplexing is that we can transmit a large number of signals to a single medium. This channel can be a physical medium like a coaxial, metallic conductor or a wireless link and will have to handle multiple signals at a time. Thus the cost of transmission can be reduced. Figure 1. Classification of multiplexing techniques. Multiplexing 10 Even though the transmission occurs on the same channel, they do not necessarily occur at the same instant.

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  eBook - ePub

  Basics of Digital Electronics

  • Banani Ghosh(Author)
  • 2023(Publication Date)
  • CRC Press

    (Publisher)

  7 Multiplexer, Demultiplexer, Encoder, Decoder Facts That Matter Multiplexer: Multiplexer means many into one A multiplexer is a circuit with many inputs but only one output. By applying control signals, we can steer any input to the output. Multiplexer is also called a data selector and control inputs are termed select inputs. Demultiplexer: Demultiplexer means one into many. A demultiplexer is a logic circuit with one input and many outputs. By applying control signals, we can steer the input signal to one of the output lines. Data selector: A synonym for multiplexer. Encoding: The process of generating the binary codes from the decimal data for a digital system is called encoding. Encoder: An encoder is a device that converts a decimal data to a coded output signal. An encoder has a number of inputs, only one of which is high at a time and an n -bit code is generated depending upon which of the input is excited. Encoder is similar to multiplexer. Decoding: The process of converting the binary numbers or codes into decimal equivalent is called decoding. Decoder: A decoder is similar to demultiplexer with the exception hat there is no data input. The only inputs are the control inputs. The control input bits produce one active output line. The decoder thus converts binary numbers or codes to its decimal equivalent

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  eBook - ePub

  Semiconductor Basics

  A Qualitative, Non-mathematical Explanation of How Semiconductors Work and How They are Used

  • George Domingo(Author)
  • 2020(Publication Date)
  • Wiley

    (Publisher)

  12 VLSI Components

  OBJECTIVES OF THIS CHAPTER

  We are now ready to talk about more complex electronic system components that are an integral part of microprocessors, computers, cell phones, and many other devices that I discuss in the next couple of chapters. These include multiplexers that select signals from multiple inputs, demultiplexers that do the opposite, registers that store intermediate results, and all type of memories. We already have all the background we need to understand how these larger components work.

  12.1 Multiplexers

  A multiplexer is a component with many inputs and one output. We call it a MUX for short. It is an essential component in almost all large electronic systems.

  The MUX is basically a selector switch, as I show in Figure 12.1 .

  The selector switch or the rotary switch on the left selects which of the four inputs I want to connect to the output, O. I show the schematic symbol of an electronic multiplexer on the right. In addition to the four inputs and the output, the symbol has two other inputs, the control inputs a and b, which determine the position of the switch arm and selects which of the inputs goes to the output.

  Figure 12.1

  A MUX selects one of the many inputs, like a rotary switch. The symbol for a MUX is on the right.

  Figure 12.2

  A 2 to 1 MUX implementation using two ANDs, one NOT, and one OR module with the truth table on the right.

  The electronic circuit that performs the MUX function is not that complicated (Figure 12.2 ).

  Recall that the output of an AND circuit is 1 only if the two inputs are 1, and 0 otherwise. Suppose now that I set the control line, a, to 1. Then one of the inputs of AND2 is always

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  eBook - ePub

  Telecommunications Engineer's Reference Book

  • Fraidoon Mazda(Author)
  • 2014(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  40

  Multiplexers

  J Hoolan,     Dowty Communications Ltd

  Publisher Summary

  The multiplexer is one of the most important components in communications networking. Its central function, from the network managers viewpoint, is to concentrate many users information on to a single transmission channel to maximize the efficiency of that channel. Given a transmission channel, there are two ways the available bandwidth can be used: first, by dividing the available bandwidth frequency spectrum into a subset of frequencies, each of which can then simultaneously use the transmission channel and allocate each frequency band to an input channel that needs to be multiplexed, or second, allocate all the available bandwidth to each channel for a fixed discrete time period. The first of these methods would be frequency division multiplexing and the latter time division multiplexing (TDM). As synchronous protocols evolved, the need to multiplex them grew; networks with remote sites that had a mix of asynchronous and synchronous terminals needed to connect them to the central site computing resource. Caught between the exponential growth of computing power and the use of asynchronous terminals as a cheap and convenient way of accessing computers, the statistical TDM was developed. It was first formulated in the early 1970s and in particular on the Arpanet network in the U.S.A from which the X.25 packet switch standard evolved.

  Contents

  Introduction Time Division Multiplexers Statistical time division multiplexing High order multiplexing Multiplexing and packet switching X.25 and OSI Physical layer standards Multiplexers in communications network The future of multiplexing

  40.1 Introduction

  The multiplexer is one of the most important components in communications networking. Its central function, from the network managers viewpoint, is to concentrate many users (or information channels) on to a single transmission channel in order to maximise the efficiency of that channel: it is used in almost every aspect of networking digital data, voice and video. This section will describe the advantages and disadvantages of different data multiplexing techniques, why these different techniques evolved to solve particular network engineering problems and how they fit in to modern networks.

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  Data Communications and Computer Networks

  A Business User's Approach

  • Curt White, , , (Authors)
  • 2021(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  As you might expect, the dynamic assignment of frequencies can be less wasteful than the static assignment of frequencies, which is found in terminal-to-mainframe computer multiplexed systems and television systems. In general, the device that accepts input from one or more users is called the Multiplexor . The device attached to the receiving end of the medium that splits off each signal to deliver it to the appropriate receiver is called the second mul-tiplexor, or deMultiplexor . In all frequency division multiplexing systems, the Multiplexor accepts input from the user(s), converts the data streams to analog sig-nals using either fixed or dynamically assigned frequencies, and transmits the com-bined analog signals over a medium that has a wide enough bandwidth to support the total range of all the assigned frequencies. The deMultiplexor then accepts the combined analog signals, separates out one or more of the individual analog sig-nals, and delivers these to the appropriate user(s). Figure 5-1 shows a simplified diagram of frequency division multiplexing. In this example, a number of radio stations have multiplexed their radio signals onto a band of frequencies. On the receiving end, individual radios employ a deMultiplexor (a tuner) to separate each radio signal from the others. Figure 5-1 Simplified example of frequency division multiplexing FM Radio Stations and Towers Listener with FM Radio 97.3 MHz 101.7 MHz 98.9 MHz To keep one signal from interfering with another signal, a set of unused frequencies called a guard band is usually inserted between the two signals to provide a form of insulation. These guard bands take up frequencies that might be used for other data channels, thus introducing a certain level of wastefulness. Frequency division multiplexing was created during a time when most if not all data and signals were analog.

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