Digital signal digital data

Signals represent information about data, voice, audio, image, video… There are many ways to classify signals but here we categorize signals as either analog (continuoustime) or digital (discretetime). Signal processing is to use circuits and systems (hardware and software) to act on input signal to give output signal which differs from the input, the way we would like to.
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Video sources produce data at very high bit rates. In many applications, the available bandwidth is usually very limited. For example, the bit rate produced by a 30 frame/s color common intermediate format (CIF) (352288) video source is 73 Mbits/s. In order to transmit such a sequence over a 64 Kbits/s channel (e.g., ISDNline), we need to compress the video sequence by a factor of 1140. A simple approach is to subsample the sequence in time and space. For example, if we subsample both chroma components by 2 in each dimension, i.e.
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For example, communicating between two PCs via a telephone line (connected between subscriber's home and local office, then between local offices, and finally between local office and another subscriber's home). The telephone line is an analog system. That means it can not be used for digital transmission. If we try to transmit digital signals over the analog system, our bit rate or bandwidth will be limited to a minimum. On a 4 kHz analog band limited system we can only transmit at a maximum rate of roughly 1 kHz. Because a 1 kHz digital signal needs a bandwidth of 5...
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Topics in Digital Communications Digital communication system advantages and disadvantages Digital communication system classification Digitization of analog signals Digital transmission systems Data communication systems Integrated Services Digital Network and other advanced digital communication systems.
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Digital filters are widely used in processing digital signals of many diverse applications, including speech processing and data communications, image and video processing, sonar, radar, seismic and oil exploration, and consumer electronics.
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Digital Signal Processing (DSP) is formally defined as a digital operation performed on an input sequence of numbers (including feedback from the result of the digital operation). The sequence of numbers can represent anything from digitised human speech to stock price data, processed to detect hidden periodicities or pattern
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Signals: In a communication system, data are propagated from one point to another by means of electromagnetic signals. A signal is a series of analogue or digital data. That is a varying voltage (either continuous or discrete) with time in an electronic communication system. Definitions of Data and Signals: Analog Data  Data represented by a continuous physical quantity whose magnitude is proportion a suitable function of the data (information). It can have more than two discrete values in contrast to digital data. ...
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Today, the data acquisition technology has found its way into virtually every segment of electronics. A digital signal processing (DSP) system accepts analog signals as input, converts those analog signals to numbers, performs computations using the numbers and eventually converts the results of the computations back into analog signals. Once converted to numbers, signals are unconditionally stable. Error detection and correction methods can be applied to store,transmit and reproduce numbers with no corruption. Signals stored digitally are really just large arrays of numbers.
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Data can be analog or digital. The term analog data refers to information that is continuous; digital data refers to information that has discrete states. Analog data take on continuous values. Digital data take on discrete values.Data can be analog or digital. Analog data are continuous and take continuous values. Digital data have discrete states and take discrete values.
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In this section, we see how we can represent digital data by using digital signals. The conversion involves three techniques: line coding, block coding, and scrambling. Line coding is always needed; block coding and scrambling may or may not be needed.
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Today, the data acquisition technology has found its way into virtually every segment of electronics. A digital signal processing (DSP) system accepts analog signals as input, converts those analog signals to numbers, performs computations using the numbers and eventually converts the results of the computations back into analog signals. Once converted to numbers, signals are unconditionally stable. Error detection and correction methods can be applied to store, transmit and reproduce numbers with no corruption....
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Unipolar All signal elements have same sign Polar One logic state represented by positive voltage the other by negative voltage Data rate Rate of data transmission in bits per second Duration or length of a bit Time taken for transmitter to emit the bit
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The reader is provided with information on how to choose between the techniques and how to design a system that takes advantage of the best features of each of them. Imminently practical in approach, the book covers sampled data systems, choosing AtoD and DtoA converters for DSP applications, fast Fourier transforms, digital filters, selecting DSP hardware, interfacing to DSP chips, and hardware design techniques. It contains a number of application designs with thorough explanations.
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One of the major functions of the physical layer is to move data in the form of electromagnetic signals across a transmission medium. Whether you are collecting numerical statistics from another computer, sending animated pictures from a design workstation, or causing a bell to ring at a distant control center, you are working with the transmission of data across network connections. Chapter 3 discusses the relationship between data, which are created by a device, and electromagnetic signals, which are transmitted over a medium.
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A computer network is designed to send information from one point to another. This information needs to be converted to either a digital signal or an analog signal for transmission. In this chapter, we discuss the first choice, conversion to digital signals.
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Converting digital data to a bandpass analog signal.is traditionally called digitaltoanalog conversion. Converting a lowpass analog signal to a bandpass analog signal is traditionally called analogtoanalog conversion. In this chapter, we discuss these two types of conversions.
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MATLAB (Matrix Laboratory) is a matrixoriented tool for mathematical programming, applied for numerical computation and simulation purposes. Together with its dynamic simulation toolbox Simulink, as a graphical environment for the simulation of dynamic systems, it has become a very powerful tool suitable for a large number of applications in many areas of research and development.
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• Analog voice data must be translated into a series of binary digits before they can be transmitted in digital transmission system. One means of doing this is called pulse amplitude modulation (PAM). • The process of converting analog signal to digital is also known as A_to_D conversion or A/D conversion. The circuit does the conversion known as A/D converter. In analog modulation (continuous wave modulation), some parameter of a sinusoidal carrier wave is varied continuously in accordance with the message signal. ...
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Digital communications is a rapidly advancing applications area. Significant current activities are in the development of mobile communications equipment for personal use, in the expansion of the available bandwidth (and hence information carrying capacity) of the backbone transmission structure through developments in optical fibre, and in the ubiquitous use of networks for data communications.
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Digital Modulation Techniques There are three ways in which the bandwidth of the channel carrier may be altered simply. It is worth emphasizing that these methods are chosen because they are practically simple, not because they are theoretically desirable. These are the altering of the amplitude, frequency and phase of the carrier sine wave. These techniques give rise to amplitudeshiftkeying (ASK), frequencyshiftkeying (FSK) and phaseshiftkeying (PSK), respectively. ASK describes the technique the carrier wave is multiplied by the digital signal f(t)....
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