Computer Network.pptx
- 1. TOPIC : DATA AND SIGNAL Supreme Knowledge Foundation Group Of Institutions Name : Ayan Das Dept : CSE Year : 3rd Subject : Computer Network Roll No: 25300121057
- 2. Analog And Digital • The physical layer’s major function is to move data in the form of electromagnetic signals over a transmission medium. The data which is used by a person is not in a form that can be transmitted over a network. • For example, a photograph has to be changed to a form that transmission media can accept. Transmission media works by conducting energy along a physical path. • Both data and the signals that represent them can be either Analog or digital in form.
- 3. Analog Data • The term analog data refers to information that is continuous. • For example, an analog clock that has hour, minute, and second hands gives information in a continuous form; the movements of the hands are continuous. • Analog data, such as the sounds made by a human voice, take on continuous values. When someone speaks, an analog wave is created in the air. This can be captured by a microphone and converted to an analog signal or sampled and converted to a digital signal.
- 4. • digital data refers to information that has discrete states. • For example, a digital clock that reports the hours and the minutes will change suddenly from 8:05 to 8:06. • Digital data take on discrete values. For example, data are stored in computer memory in the form of Os and 1s. They can be converted to a digital signal or modulated into an analog signal for transmission across a medium. Digital Data
- 5. Analog Signal • An analog signal has infinitely many levels of intensity over a period of time. As the wave moves from value A to value B, it passes through and includes an infinite number of values along its path. • The curve representing the analog signal passes through an infinite number of points.
- 6. • A simple analog signal is a sine wave that cannot be further decomposed into simpler signals. Analog Signal(Cont.…)
- 7. • A digital signal, on the other hand, can have only a limited number of defined values. • Although each value can be any number, it is often as simple as 1 and 0. • The vertical lines of the digital signal, however, demonstrate the sudden jump that the signal makes from value to value. Digital Signal
- 8. Periodic And Nonperiodic • Both analog and digital signals can take one of two forms: periodic or nonperiodic (sometimes refer to as aperiodic, because the prefix a in Greek means "non"). • A periodic signal completes a pattern within a measurable time frame, called a period, and repeats that pattern over subsequent identical periods. • The completion of one full pattern is called a cycle. • A nonperiodic signal changes without exhibiting a pattern or cycle that repeats over time. • Both analog and digital signals can be periodic or nonperiodic. • In data communications, we commonly use periodic analog signals and nonperiodic digital signals.
- 9. Periodic Analog Signals • Periodic analog signals can be classified as simple or composite. • A simple periodic analog signal, a sine wave, cannot be decomposed into simpler signals. • A composite periodic analog signal is composed of multiple sine waves.
- 10. • The sine wave is the most fundamental form of a periodic analog signal. • When we visualize it as a simple oscillating curve, its change over the course of a cycle is smooth and consistent, a continuous, rolling flow. • Each cycle consists of a single arc above the time axis followed by a single arc below it. • A sine wave can be represented by three parameters: 1. The peak amplitude 2. The frequency 3. The phase SineWave
- 11. • The peak amplitude of a signal is the absolute value of its highest intensity, proportional to the energy it carries. • For electric signals, peak amplitude is normally measured in volts. Peak AmplItude
- 12. • Period refers to the amount of time, in seconds, a signal needs to complete 1 cycle. • Frequency refers to the number of periods in 1 s. • period and frequency are just one characteristic defined in two ways. Period is the inverse of frequency, and frequency is the inverse of period. Period And Frequency
- 13. Two Signals With The Same Amplitude And Phase, But Different Frequencies
- 14. • The term phase, or phase shift, describes the position of the waveform relative to time 0. • If we think of the wave as something that can be shifted backward or forward along the time axis, phase describes the amount of that shift. • It indicates the status of the first cycle. • Phase is measured in degrees or radians. • A phase shift of 360° corresponds to a shift of a complete period. • a phase shift of 180° corresponds to a shift of one- half of a period. • and a phase shift of 90° corresponds to a shift of one-quarter of a period. Phase
- 15. Three Sine Waves With The Same Amplitude And frequency, But Different Phases
- 16. Thank You