What is Waveform: Definition and 129 Discussions

In electronics, acoustics, and related fields, the waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time.In electronics, the term is usually applied to periodically varying voltages, currents, or electromagnetic fields. In acoustics, it is usually applied to steady periodic sounds—variations of pressure in air or other media. In these cases, the waveform is an attribute that is independent of the frequency, amplitude, or phase shift of the signal. The term can also be used for non-periodic signals, like chirps and pulses.
The waveform of an electrical signal can be visualized in an oscilloscope or any other device that can capture and plot its value at various times, with a suitable scales in the time and value axes. The electrocardiograph is a medical device to record the waveform of the electric signals that are associated with the beating of the heart; that waveform has important diagnostic value. Waveform generators, that can output a periodic voltage or current with one of several waveforms, are a common tool in electronics laboratories and workshops.
The waveform of a steady periodic sound affects its timbre. Synthesizers and modern keyboards can generate sounds with many complicated waveforms.

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  1. O

    Grid tie inverter distorting waveform

    I've just wired in a 1kw grid tie inverter, feeding the power from solar panels into the mains grid, ( in Thailand , so no rules or regulations). There are some problems I've noticed. Toaster buzzes , but works. Induction cooker won't work, lights come on , fan works but no heat delivered, when...
  2. X

    Why is the voltage regulator waveform identical to the diode bridge waveform?

    I am doing a homework problem for my Power Electronics class. I have attached the relevant image. My question is, (referring to the TOP plot) why is the voltage regulator waveform (purple curve) identical to the voltage waveform coming from the diode bridge (green curve)? Shouldn't it be the...
  3. J

    Photon Momentum varies along waveform?

    An M.I.T. Physics lecture mentioned B and E crossing over the x-axis as lowest energy state/position of the wave(s). Along the x axis, path of photon, is photon momentum here the lowest also? Does momentum vary? For a tiny target, if a photon collides at this exact point is there no momentum...
  4. B

    How to Determine the Correct Fourier Series for a Given Waveform?

    Homework Statement Sketch the waveform and develop its Fourier series. f(\omega t)= \begin{cases} 0 & if & 0 \leq \omega t \leq \frac{π}{2} \\ V*sin(\omega t) & if & \frac{π}{2} \leq \omega t \leq π\\ 0 & if & π \leq \omega t \leq \frac{3π}{2} \\ V*sin(\omega t) & if & \frac{3π}{2} \leq...
  5. C

    Sketch waveform to represent the transient response

    Homework Statement Sketch, on a set of common axes, waveforms to represent the transient response of circuits having transfer functions with the following parameters: a) ζ = 0.5, ω = 1×10^3 rad s^-1 b) ζ = 0.2, ω = 2×10^3 rad s^-1 c) ζ = 2, ω = 1×10^3 rad s^-1 Homework...
  6. E

    Waveform of Photons: Current Thinking & Analysis

    What is the current thinking about the waveform of photons? How can finite signals in the time domain produce a discrete frequency response in the frequency domain? As anyone who has worked with signal analysis remembers, the Fourier transforms of time signals in the real world always produce...
  7. S

    Discovering the Type of Waveform from a Fourier Series | Homework Help

    Homework Statement what type of waveform would this make ? Homework Equations V(t)=2/π(sin(ωt)+1/2sin(2ωt)+1/3sin(3ωt)+1/4sin(4ωt)+...) 5sin(ωt)+5sin(2ωt)+5sin(3ωt)+5sin(4ωt)... The Attempt at a Solution
  8. anthonyk2013

    Sketching Complex Waveform with Equation y=100sinωt+30sin(3ωt-π/2)

    Having some trouble with this question, A complex wave is described by equation, y=100 sin ωt+30 sin(3ωt-∏/2) A) on the same axis sketch and label, 1)one cycle of the fundamental waveform 2)the third harmonic 3) the complex waveform(y) ω=2∏f T=2∏/ω Not sure where to...
  9. T

    Q) What are the equations for waveforms that lead and lag by specified angles?

    Homework Statement Q) State the equations of the wave forms which: a) Leads sin ωt by ∏/2 and b) Lags sin (ωt+∏/6) by ∏/3 Homework Equations I could not think of any relevant equations. The Attempt at a Solution a)Sin ωt will be when t=0 Sin ω(t-a) will be 0 when t-a, since...
  10. S

    Wanting program or app for waveform analysis

    Hi everyone, My 14 year old son who is an avid musician and composer, wants to do a science project that involves waveform analysis of tonal harmony in Western music, for example, why certain chords and chord progressions are more pleasing than others and whether the interference patterns...
  11. D

    Engineering Plot the waveform of clipper circuit

    Homework Statement Plot the output voltage V0 versus time of the circuit below. Assume Vgamma=0 for the diode. Clearly mark the values on the plot for full credit Homework Equations KVL KCL The Attempt at a Solution I have uploaded mt attempt the dotted line is the input waveform...
  12. Jarvis323

    Question about how to interpret the graph of this waveform.

    Homework Statement The question is in regards to a homework problem, but I only need clarification on how to interpret the graph of a waveform. Homework Equations N.A. The Attempt at a Solution N.A. I've attached the image. I am assuming that one cycle of the waveform takes...
  13. R

    Following collapse of the waveform

    A few new student questions: following collapse of the waveform, does the waveform ever reform? If so, and if entangled particles are involved, does the entangled twin reform as well? And if so, does this require forward progression in time, in other words, might the entangled twin decollapse...
  14. D

    Find average and rms values of the waveform

    Homework Statement The problem is located here http://www.chegg.com/homework-help/determine-average-rms-value-waveform-depicted-fig-1136-chapter-11-problem-26e-solution-9780073529578-exc Homework Equations Rms=sqrt(1/T∫ from 0 to T of i(t)^2 DT ) Average= couldn't find an equation in...
  15. M

    Is this a waveform or random data?

    Hi there, I have recently come across some data that is supposed to be random, but I don't think it is. I graphed it out and it sure doesn't look random. I also ran a couple of statistical tests such as the runs test, and they all say "not random." Visually, the data looks like a piece of...
  16. C

    Estimating the damping ratio from the waveform graph

    Homework Statement From the waveform shown below, estimate a) the damping ratio ζ (you may compare response with a standard chart); b) the forced or damped frequency of oscillation; and c) the natural or undamped frequency of oscillation. Homework Equations Since the waveform is under...
  17. M

    RMS of complex waveform (acoustics)

    Hey everyone, just got a quick question in acoustics. I am mainly looking for a mathematical understanding Homework Statement Consider two harmonic plane progressive waves of the form \tilde{P(x)} = \tilde{A}e-jkx and\tilde{P(x)} = \tilde{B}e+jkx traveling in opposite directions. Showing...
  18. S

    How Do You Calculate the Average Value of a Square Waveform?

    Homework Statement Alpha=0.91 ,beta=2.92, T0=0.91 Homework Equations The value of a0 for the square waveform The Attempt at a Solution 1/T0 * area = 1/0.91*(2.92-0.91)*0.91
  19. C

    Power of Burst waveform going through an amplifier

    Hi all, How would I calculate theoretical power of: 1Vpp 1Mhz (sinewave) 200 cycles 100ms interval 50Ω load This waveform is going into a 55db amplifier. Any help would be great. Thanks, Mark
  20. P

    Asymmetric Clipped Waveform - find RMS

    I have an asymmetrical clipped repeating waveform and I want to be able to find the root mean square. The function is as follows, with r and b constants: y(t) = ((exp(sin(t)*b)-exp(-sin(t)*b*r))/(exp(sin(t)*b)+exp(-sin(t)*b)))*(1/b) This is pretty computationally heavy. What are some...
  21. K

    AC Voltage across diode waveform

    I am wondering how the waveform of AC voltage measured across a diode would look like? What about the waveform of the resistor connected in series with this diode? Please help .
  22. A

    PSPICE simulation with Schematic of Waveform Selector

    Homework Statement Hi in response to my previous thread (principles behind the waveform selector circuit), I would now like to run a SPICE simulation using the PSPICE schematics software to obtain the theoretical values before entering my lab session. I have uploaded the schematic for your...
  23. A

    Engineering Principles behind waveform selector circuit

    Homework Statement Hi i have a practical project that i am working on. I am working on a waveform selector circuit. My circuit is part two of three circuits. The first circuit is a signal generator followed by the waveform selector and then a filter rectifier. I am required to produce a report...
  24. D

    How to Convert Phasor Back to Time Domain for Evaluating Current at t=2s?

    Homework Statement Homework Equations ω=2\pif The Attempt at a Solution After converting it from time domain to phasor domain my answer is I=17.6\angle25mA. How am I suppose to show the current at time = 2 sec? Do I just plug in 2 and find the sine of it?
  25. C

    AC Voltage Waveform: Frequency, Time, RMS & Instantaneous Value

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  26. U

    Help Plotting a Signal Waveform

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  27. J

    Average waveform or calculated values?

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  28. H

    DO-160 Pin Injection waveform generation

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  29. J

    Exam Revision: Stuck on RMS derivation from voltage waveform diagram

    Homework Statement I've spent the last hour trying to get this, and it's starting to drive me crazy! I'm not sure how to approach the waveform, as there are two forms? I'm guessing that the period in this case is 4 seconds, and they've included a second wave to reiterate that? Homework...
  30. F

    AM and DSBSC waveform comparison ?

    Hello, I am wondering what sort of visual differences you would see between an AM modulated waveform with carrier and a DSBSC waveform (suppressed carrier) in the time domain on an oscilloscope. Any help would be appreciated.
  31. V

    The difference of Back EMF waveform shape of BLDC and brushless PM generator

    I am a bit confuse on the back EMF waveform shape of the brushless permanent magnet machine. As I know brushless DC permanent magnet motor has a trapezoidal shape back EMF waveform. If I use this motor as a generator, do I still get the same waveform shape or I will get a sinusoidal waveform?
  32. F

    AM waveform in frequency domain

    Hello, I need to sketch the frequency domain for the following AM waveform showing total bandwidth and frequency. 8sin(2pi500kt - 4cos(2pi530kt) + 4cos(2pi(470kt) I have attached an attempt I have made. Does anyone know if I have this correct or not ? Thanks kindly for any input.
  33. O

    How Do You Calculate AC Waveform Components and Errors?

    Homework Statement An A.C. voltage, V comprises of a fundamental voltage of 100V rms at a frequency of 120Hz, a 3rd harmonic which is 20% of the fundamental, a 5th harmonic which is 10% of the fundamental and at a phase angle of 1.2 radians lagging. i) Write down an expression for the...
  34. K

    Waveform conversion of Analogue to Digital

    I have an assessment at the moment and one of the questions is about the conversion of an Analogue wave to Digital one. I know how it is graphed and the basic concepts but I have no idea how to express it being forced into a grid. I was wondering if anyone knew any websites or books which has...
  35. T

    Engineering Determining motor speed from PWM waveform

    As part of a lab report I have to determine the speed of a motor from the PWM waveform. The motor in question is a lego motor, of type at disassembled at http://www.philohome.com/motors/motor.htm. It has three coils on the rotor and a 4 pole permanent magnet stator. This is the waveform I...
  36. T

    I Continious FT of a rectangle waveform is real valued, but the DFT of it is not?

    Continious FT of a rectangle is real valued but DFT of it is not!? Continious Fourier Transform of a rectangle with amplitude of 1 between [-u,u] is a real valued function (u is a positive number). Actually it is a sinc function. However when I use discrete Fourier Transform (fft) I obtain...
  37. E

    Creating a triangular waveform in Matlab

    Homework Statement Create 512 element triangular waveform (In Matlab) x(k)= k 0≤k≤7 8-k 8≤k≤23 -32+k 24≤k≤31 For 0≤k≤31 repeating every 32 elements. Homework Equations N/A The Attempt at a Solution Ok so I am confused on how to code...
  38. pairofstrings

    How to write a function by analysing/looking at a waveform?

    How to write a function by analysing/looking at a signal? Hello everyone. I have attached one waveform/signal. I want to know how can I represent it mathematically. I have been studying about functions that are already defined, say, a function like this f(x)=4Sinx + 2Cosx | x is in some...
  39. E

    Impulse Waveform: Representing Data

    How do we represent data in terms of impulse waveform ??
  40. N

    How to recognize patterns in an analog waveform?

    Hi All As the title of this thread suggest, I am looking for ways to recognize patterns in an analog waveform. Well the obvious answer to this question is use Artifical Neural Network (ANN) as ( from the text on google) its been used for pattern recognition and all sorts of stuff. I've been...
  41. W

    Finding Fourier Coefficients for a Function's Waveform

    Homework Statement For an even function, the Fourier series takes the form ^{\infty}_{n=0}\Sigma A_n cos(\frac{2\pi n x}{\lambda}) where \lambda is the wavelength of the function. In this problem you will see how to find the Fourier coefficients A_n. a.) Prove that A_0 =...
  42. H

    Diode placement and AC waveform across load?

    Hi all. A transformer is driven with a square wave pulse. The transformer has three secondary coils all in series, a diode is placed between two of them which is forward biased during the on time. The coils are used to charge a capacitor and limit current. When the transformer is pulsed...
  43. B

    Suggested waveform Amplifier for electromagnetoc coil testing?

    Hi everyone, I am currently doing some experimentation with electromagnetic coils, I realize I will need a waveform amplifier for the testing using my rsr32 function generator. Could someone point me in the direction of a decently priced one?
  44. M

    Electromagnetic pickup/reluctor waveform

    I'm trying to design a pickup/reluctor that produces a specific waveform. I'm using an automotive ignition pickup and expermenting with different shapes of reluctor but the results I'm getting aren't making any sense. The pickup/reluctor are of the familiar design with a pickup coil wound...
  45. N

    Producing Waveform from Frequency Table

    I'm working on a voice synthesizer. I have my computer set up to accept an 8-bit 44kHz waveform. I'm feeding it sines, adding sines together, and so on. It works great. However, I want to generate a sound given a frequency histogram. That is, I want to generate noise that has a specific...
  46. C

    Capacitance: given V waveform, find max. power

    Homework Statement A capacitance of 60 \mu F has the voltage waveform shown in Fig. 2-36. Find P_{max}. [PLAIN]http://img828.imageshack.us/img828/5255/unled2copy.jpg Homework Equations p(t)=i(t)u(t)=\left(C\frac{du(t)}{dt}\right)u(t)The Attempt at a Solution When is power at maximum? Is it...
  47. C

    Inductance: given V waveform, find I

    Homework Statement An inductance of 3 mH has the following voltage waveform: for 0<t<2\text{ }ms, v=15\text{ }V; for 2ms<t<4ms, v=0; and for 4\text{ }ms<t<6\text{ }ms, v=-30\text{ }V. Assuming i(0)=0, find the current at time (a) 1 ms, (b) 4 ms, (c) 5 ms. Ans. (a) 5 A; (b) 10 A; (c) 0Homework...
  48. PainterGuy

    Full wave rectification using CTT and amplitude of output waveform

    Hello, :smile: I did an experiment on full wave rectification using center tap transformer. The transformer read: Input 220V, Output 12V, 12V. I used two diodes and 1 micro farad capacitor. As you see capacitor's capacitance is very little so it didn't effect the overall output because I...
  49. PainterGuy

    Do both circuits have the same output waveform?

    Hi, :wink: In the link given below circuit #1 and #2 are same except that they have opposite polarities for the battery V. On the left bottom there is output waveform after the clipping. In the beginning I was thinking that output for both circuits, #1 and #2, will be same. But now I am...
  50. M

    Output waveform of emitter amplifier

    Homework Statement What causes the output distortion seen in the above diagram? Output on right, input on left. The Attempt at a Solution This isn't homework, just something I can't figure out, playing with a simulator. The gain here is dependent on the input voltage... but why is the output...
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