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This module serves as an introduction to working in the frequency domain and thinking of signals in terms of their spectral components. The Fourier transformcan be used to represent any signal in terms of frequency instead of time and facilitates the computation of the transfer function of a system.

In developing ways of analyzing linear circuits, we invented the impedance method because it made solvingcircuits easier. Along the way, we developed the notion of a circuit's frequency response or transfer function. This notion,which also applies to all linear, time-invariant systems, describes how the circuit responds to a sinusoidal input when weexpress it in terms of a complex exponential. We also learned the Superposition Principle for linear systems: The system'soutput to an input consisting of a sum of two signals is the sum of the system's outputs to each individual component.

The study of the frequency domain combines these two notions--a system's sinusoidal response is easy to find anda linear system's output to a sum of inputs is the sum of the individual outputs--to develop the crucial idea of a signal's spectrum . We begin by finding that those signals that can be represented as a sum of sinusoids is very large. Infact, all signals can be expressed as a superposition of sinusoids .

As this story unfolds, we'll see that information systems rely heavily on spectral ideas. For example, radio,television, and cellular telephones transmit over different portions of the spectrum. In fact, spectrum is so important thatcommunications systems are regulated as to which portions of the spectrum they can use by the Federal Communications Commissionin the United States and by International Treaty for the world (see Frequency Allocations ). Calculating the spectrum is easy: The Fourier transform defines how we can find a signal's spectrum.

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
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emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
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Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Fundamentals of electrical engineering i. OpenStax CNX. Aug 06, 2008 Download for free at http://legacy.cnx.org/content/col10040/1.9
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