datasignala - Data and Signals Data must be transformed to...

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Data and Signals Data must be transformed to electronic signals (why?) Analog data: Continuous information, e.g., voice has a value at any time. Analog clock have values at any time! Digital data: Discrete state information. e.g., digital clock. Analog signal: They have infinitely many levels over a period of time. Digital signals: They have limited number of defined values. Periodic Signals: “Repeat a pattern every measurable time frame, “period” or “cycle”. (most used for analog signals) Non-Periodic (Aperiodic) Signals: No pattern or cycle. (most used for digital signals) 3.6 Figure 3.1 Comparison of analog and digital signals
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Periodic Analog Signals 3.9 Figure 3.2 A sine wave Frequency (f) = 1/T and T = 1/f Phase: It is the position of waveform relative to time = 0. Ex: The “sine” phase is 0, where as the “cos” phase = π /2 3.12 Figure 3.3 Two signals with the same phase and frequency, but different amplitudes
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3.15 Figure 3.4 Two signals with the same amplitude and phase, but different frequencies 3.23 Figure 3.5 Three sine waves with the same amplitude and frequency, but different phases Wave length: It relates the frequency / period of a signal to its propagation speed in the medium. In case of “light” over fiber: λ = c / f c = propagation speed of light signal. f = frequency of light signal. λ = Wave length of light signal.
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Time vs. Frequency domain: The amplitude values are plotted versus time in case of time domain signals. 3.26 Figure 3.7 The time-domain and frequency-domain plots of a sine wave The amplitude is shown for each frequency component of a signal in the frequency domain. The above sin(6t) has one frequency of 6 Hz, with 5 volt peak amplitude. 3.29 Figure 3.8 The time domain and frequency domain of three sine waves
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Composite Signals: Every composite signal is made of many sine waves of different amp’s, freq’s, phases. (Fourier analysis) A periodic composite signal can be decomposed into a number of signals with discrete frequencies in the frequency domain . Whereas, a non-periodic composite signal is a group of sine waves with continuous frequencies in the frequency domain. 3.34 Figure 3.9 A composite periodic signal 3.35 Figure 3.10 Decomposition of a composite periodic signal in the time and frequency domains
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Whereas, a non-periodic composite signal is a group of sine waves with continuous frequencies in the frequency domain. 3.37 Figure 3.11 The time and frequency domains of a nonperiodic signal Band width: (for only composite signals). Refer fig 3.12 BW cs = f h – f l Hz 3.39 Figure 3.12 The bandwidth of periodic and nonperiodic composite signals Transmission Impairment
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Causes: 1) Attenuation: Loss of energy as a function of the signal traveling distance and its power. Decibel: Unit measure of signal’s power loss or gain
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datasignala - Data and Signals Data must be transformed to...

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