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# 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
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
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
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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