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Unformatted text preview: 1 • Signals Signal a transmitted effect conveying a message A essential characteristic of a signal is that of change, since it must be capable of carrying information. The change must be partly unpredictable. It is also necessary to discuss the sinusoidal or pulse waveforms because they can be modulated to carry information. Signal can be: Temporal (function of time) Spatial (function of space) Spatialtemporal We use f(t) for all such signals 2 • Power and Energy ) t ( f P inst 2 = The instantaneous power in a signal f(t) is defined as Because signal is usually represented by voltage or current, the corresponding units will be mean squares volts of mean squares amperes. (not Watts). The energy in small time interval δt is t ) t ( f δ 2 The total energy over all time: dt ) t ( f E ∫ ∞ ∞ = 2 ∫ ∞ → = 2 2 2 1 / T / T T d t ) t ( f T lim P The mean power : 3 Example: The rectangular pulse of height A and width θ, shown in the figure below has instantaneous power θ t A P inst ≤ ≤ = 2 for and energy θ A E 2 = It has zero mean power. 4...
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This note was uploaded on 01/23/2012 for the course EE 4580 taught by Professor Gu during the Fall '10 term at LSU.
 Fall '10
 GU

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