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Lecture Wireless and mobile computing – Chapter 2: Wireless and mobile computing transmission fundamentals

Lecture 2 - Wireless and mobile computing transmission fundamentals. The following will be discussed in this chapter: Transmission fundamentals, signals for conveying information, time domain concepts, frequency domain concepts, frequency/time domain,. | Wireless and Mobile Computing Transmission Fundamentals Lecture 2 Transmission Fundamentals Signals for Conveying Information Time Domain Concepts Frequency Domain Concepts Relationship between Data Rate and Bandwidth 1 Signals for Conveying Information Electromagnetic signals used as a means to transmit information. An electromagnetic signal is a function of time But it can also be expressed as a function of frequency i-e the signal consists of components of different frequencies Frequency domain view of a signal is far more important to an understanding of data transmission than a time domain view. 2 Time Domain Concepts A time domain electromagnetic signal can be either analog or digital. Analog Signal An analog signal is one in which the signal intensity varies in a smooth fashion over time no breaks or discontinuities in the signal 3 Analog signal might represent speech Analog Time Domain Concepts cont. Digital signal is one in which the signal intensity maintains a constant level for some period of time and then changes to another constant level 4 Digital Waveforms Digital signal might represent binary 1s and 0s Time Domain Concepts cont. Periodic signal in which the same signal pattern repeats over time 5 (a) Sine wave (b) Square wave Examples of Periodic Signals Mathematically, a signal s(t) is defined to be periodic if and only if where the constant T is the period of the signal ( T is the smallest value that satisfies the equation) . 5 Time Domain Concepts cont. Aperiodic signal: A signal that does not exhibit a pattern or repeating cycle. 6 Both the Analog and Digital can be periodic or aperiodic. but in data communication periodic analog signals and aperiodic digital signals are used. Time Domain Concepts cont. Analog signal Signal intensity varies smoothly with no breaks Digital signal Signal intensity maintains a constant level and then abruptly changes to another level Periodic signal Signal pattern repeats over time Aperiodic signal . | Wireless and Mobile Computing Transmission Fundamentals Lecture 2 Transmission Fundamentals Signals for Conveying Information Time Domain Concepts Frequency Domain Concepts Relationship between Data Rate and Bandwidth 1 Signals for Conveying Information Electromagnetic signals used as a means to transmit information. An electromagnetic signal is a function of time But it can also be expressed as a function of frequency i-e the signal consists of components of different frequencies Frequency domain view of a signal is far more important to an understanding of data transmission than a time domain view. 2 Time Domain Concepts A time domain electromagnetic signal can be either analog or digital. Analog Signal An analog signal is one in which the signal intensity varies in a smooth fashion over time no breaks or discontinuities in the signal 3 Analog signal might represent speech Analog Time Domain Concepts cont. Digital signal is one in which the signal intensity maintains a constant