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Frequency domain - Wikipedia, the free encyclopedia Frequency domain is a term used to describe the analysis of mathematical functions with respect to frequency. A frequency domain representation also includes information on the phase shift that must be applied to each frequency in order to be able to recombine the frequency components to recover the original time signal. In using the Laplace, Z-, or Fourier transforms, the frequency spectrum is complex and describes the frequency magnitude and phase. en.wikipedia.org /wiki/Frequency_domain   (266 words)

Priism Help: 2D Filter (Frequency domain) These filters are applied in the frequency domain; the advantages or disadvanteges of this technique as opposed to the filtering in the spatial domain that is done with 2D Filter or the 2D convolution applications are Frequency domain techniques treat the right edge (after padding) as contiguous with the left edge; the top and bottom are handled similarly. The frequency which marks the transition between the slightly attenuated and highly attenuated frequencies is the cutoff frequency: the frequency response at the cutoff frequency is 1 / sqrt(2). www.msg.ucsf.edu /IVE/IVE3.3_HTML/FFilter2D.html   (1513 words)

Frequency spectrum - Wikipedia, the free encyclopedia Familiar concepts associated with a frequency are colors, musical notes, radio/TV channels, and even the regular rotation of the earth. When all the visible frequencies are present in equal amounts, the effect is the "color" white, and the spectrum is a flat line. Because of reversibility, the Fourier transform is called a representation of the function, in terms of frequency instead of time, thus, it is a frequency domain representation. en.wikipedia.org /wiki/Frequency_spectrum   (736 words)

Digital Filters - Frequency Filters The result in the spatial domain is equivalent to that of a smoothing filter; as the blocked high frequencies correspond to sharp intensity changes, i.e. We obtain the filter function of a bandpass by multiplying the filter functions of a lowpass and of a highpass in the frequency domain, where the cut-off frequency of the lowpass is higher than that of the highpass. To perform the frequency filtering we transform both the image of the house and the mask into the Fourier domain where we multiply the two images with the effect that the frequencies occurring in the mask remain in the output while the others are set to zero. homepages.inf.ed.ac.uk /rbf/HIPR2/freqfilt.htm   (2854 words)

Frequency Domain Representation   (Site not responding. Last check: 2007-10-22) If the frequency of the source is fixed, then a complete analysis in either the time domain or the frequency domain is possible. If the frequency of the voltage source is varied, the impedance of each energy storage element changes, and the response of the circuit varies as a function of the input frequency. The frequency response of a circuit is a quantitative description of its behavior in the frequency domain. www.ee.duke.edu /~cec/final/node101.html   (216 words)

The Calculation of Time Domain Frequency Frequency offset may be removed from phase data by subtracting a line determined by the average of the first differences, or by a least-squares linear fit. Frequency drift may be removed from the phase data by a least-squares or 3-point quadratic fit [5], or by subtracting the average of the second differences. Frequency drift may be removed from frequency data by subtracting a least-squares linear fit, by subtracting a line determined by the first-differences of the frequency data or by calculating the drift from the difference between the two halves of the data. www.ieee-uffc.org /freqcontrol/paper1ht.html   (3604 words)

Frequency Domain   (Site not responding. Last check: 2007-10-22) In the frequency domain, sounds are represented in a frequency by amplitude and/or phase diagram. The next figure is a frequency domain representation of the 200 Hz sine wave we saw in the first figure. In the frequency domain, this sound is represented by a line at a point on the frequency axis corresponding to 200 Hz and with a length corresponding to its amplitude. www.asel.udel.edu /speech/tutorials/acoustics/freq_domain.html   (1226 words)

Priism Help: 2D Filter (Frequency domain) These filters are applied in the frequency domain; the advantages or disadvantages of this technique as opposed to the filtering in the spatial domain that is done with 2D Filter or the 2D convolution applications are The frequency response over the set of frequencies that are only slightly attenuated (the passband) is maximally flat as is the frequency response over the set of frequencies that is highly attenuated (the stopband). The first two parameters are the central frequency as fraction of the Nyquist frequency and sigma as a fraction of the Nyquist frequency for the Gaussian in the (1-Gaussian) term. www.msg.ucsf.edu /IVE/IVE4_HTML/FFilter2D.html   (2637 words)

Glossary - Frequency Domain   (Site not responding. Last check: 2007-10-22) This means that in the corresponding spatial domain image I the intensity values vary from dark to light and back to dark over a distance of 10 pixels, and that the contrast between the lightest and darkest is 40 gray levels (2 times 20). The spatial frequency domain is interesting because: 1) it may make explicit periodic relationships in the spatial domain, and 2) some image processing operators are more efficient or indeed only practical when applied in the frequency domain. In most cases, the Fourier Transform is used to convert images from the spatial domain into the frequency domain and vice-versa. homepages.inf.ed.ac.uk /rbf/HIPR2/freqdom.htm   (172 words)

Frequency domain Info - Encyclopedia WikiWhat.com   (Site not responding. Last check: 2007-10-22) Speaking non-technically, a time domain graph shows how a signal changes over time, whereas a frequency domain graph shows how much of the signal lies within each given infinitesimal frequency band over a range of frequencies. A spectrum analyser on a stereo is an example of a frequency domain graph. If a signal is known in the time domain, a frequency domain graph can be constructed using a technique known as a Fourier transform. www.wikiwhat.com /encyclopedia/f/fr/frequency_domain.html   (114 words)

9.1 Introduction to the frequency domain   (Site not responding. Last check: 2007-10-22) High frequencies are noted by concentrations of large amplitude swings in the small checkerboard pattern. The easiest way to determine the frequency composition of signals is to inspect that signal in the frequency domain. The further from the origin it is, the higher the spatial frequency it represents. www.netnam.vn /unescocourse/computervision/91.htm   (679 words)

Chapter 4: The Frequency Domain   (Site not responding. Last check: 2007-10-22) In Chapter 2 we observed that the sum of a cosine wave and a sine wave of the same frequency is equal to a phase-shifted cosine wave of the same frequency. The meaning of negative frequencies is easiest to understand in terms of counter-rotating phasors (see exercise 2.3) with real components pointing in the same direction (and therefore reinforcing) but with imaginary components pointing in opposite directions (and therefore canceling). The former refers to the frequency of the trigonometric basis functions, whereas the latter refers to the frequency of the complex exponentials. research.opt.indiana.edu /Library/FourierBook/ch04.html   (3281 words)

Image Filtering in the Frequency Domain   (Site not responding. Last check: 2007-10-22) The reason for doing the filtering in the frequency domain is generally because it is computationally faster to perform two 2D Fourier transforms and a filter multiply than to perform a convolution in the image (spatial) domain. The fourier transform of the rectangular pulse is the two dimensional equivalent of the sync function, the fourier transform of white noise is a constant. Applying a high pass filter frequency domain is the opposite to the low pass filter, that is, all the frequencies below some cutoff radius are removed. astronomy.swin.edu.au /~pbourke/analysis/imagefilter   (648 words)

Filtering Images in the Frequency Domain A -1 argument to the FFT function indicates a transformation from the spatial to the frequency domain, and a 1 indicates the reverse transformation. In general, the low frequency terms usually represent the general shape of the image and the high frequency terms are needed to sharpen the edges and provide fine detail. Different frequencies are represented at different distances from the origin (usually represented as the center of the image) and different directions from the origin represent different orientations of features in the original image. www.dfanning.com /ip_tips/freqfiltering.html   (840 words)

Matlab tutorial - 4   (Site not responding. Last check: 2007-10-22) Frequency domain methods, however, can also be used in situations when the exact transfer function is not known. The frequency response of a system can be measured in the laboratory by choosing different sinusoidal inputs and measuring the magnitude and phase of the sinusoidal output, or by using a special type of instrument. By using a log scale for the frequency and the magnitude, and a linear scale for the phase, the composition of two systems (in series) is easily accomplished by adding together their Bode plots. www-personal.engin.umich.edu /~tilbury/tutorials/matlab4.html   (1120 words)

9.4 Filtering in the frequency domain   (Site not responding. Last check: 2007-10-22) Convolving two functions in the spatial domain is the same as multiplying their spectra in the frequency domain. The two methods of creating a filter mask are to transform a convolution mask from the spatial domain to the frequency domain or to calculate a mask within the frequency domain. The frequencies in this region are multiplied by 1.0 and therefore pass unaffected. www.netnam.vn /unescocourse/computervision/94.htm   (882 words)

Stable32 Frequency Domain Functions Then the time domain properties of this noise are analyzed using the overlapping Allan deviation with the Run function. Choose the Power function and calculate a power spectrum for the phase data, using the default 10 MHz carrier frequency and £(f) power spectral density type, the SSB phase noise to signal ratio in a 1 Hz BW as a function of sideband frequency, f. The Stable32 Domain function can be used to determine the PSD values that correspond to the time domain parameters that were used to generate the simulated power-law noise. www.wriley.com /paper5ht.htm   (552 words)

Frequency synthesis of landscapes (and clouds)   (Site not responding. Last check: 2007-10-22) Frequency synthesis is based upon the observation that many "natural" forms and signals have a 1/f frequency spectra, that is, their spectra falls off as the inverse of some power of the frequency where the power is related to the fractal dimension. This filter is applied to both the real and imaginary values of the harmonics in the frequency domain. astronomy.swin.edu.au /~pbourke/terrain/freqland   (417 words)

Frequency Domain Filtering According to discrete sampling theory, the maximum usable frequency is 0.5 cycles per pixel because at least two pixels are required to define the one cycle of the wave. This frequency is called the "Nyquist Frequency" (0.5 cycles/pixel) and is the highest frequency (of intensity variation) that can be accurately reproduced in our data. If the Nyquest frequency  is given in cycles/cm then it will vary for different pixel sizes. www.uab.edu /radiography/Nmt422/Frequency_Domain_Filtering.htm   (414 words)

An Overview of Frequency-Domain Measurements - Tutorial - Developer Zone - National Instruments The time and frequency domains, which are related to each other, are the most common ways of viewing, manipulating, and analyzing any signal of interest. In general, the frequency response is simply the response of a system to sinusoidal inputs at different frequencies. The frequency response is the magnitude and phase differences between the input and output sinusoids across the frequency range of interest. zone.ni.com /devzone/conceptd.nsf/webmain/DFB1F12D07F164AF86256CD40074D8BF?opendocument&node=dz00000_us   (652 words)

Filtering in the Frequency Domain   (Site not responding. Last check: 2007-10-22) By sampling in the frequency domain, we have the potential for aliasing in the time domain (sampling in one domain, be it time or frequency, can result in aliasing in the other) unless we sample fast enough. Because sampling in the frequency domain causes repetitions of the unit-sample response in the time domain, sketch the time-domain result for various choices of the DFT length N. Frequency-domain filtering, diagrammed in figure 1, is accomplished by storing the filter's frequency response as the DFT H(k), computing the input's DFT X(k), multiplying them to create the output's DFT Y(k) =H(k) X(k), and computing the inverse DFT of the result to yield y(n). cnx.org /content/m0532/latest   (805 words)

Frequency Domain, Power Spectra, and Signal Sampling Many waveforms in industrial environments have noise and multiple frequencies which make it difficult to determine the various frequencies represented in the waveform and the intensity (or portion of the total power) at each frequency. The power spectrum is graphed in the frequency domain, as opposed to the time domain. In the frequency domain graph, the x axis represents the frequency (usually in a log scale to best cover a large range) and the y axis represents the relative portion of the signal at that frequency. www.mines.edu /academic/courses/eng/EGGN383/ref/r21   (625 words)

[No title] Finally, the output of the hall sensor was analyzed in frequency domain, through the use of an FFT algorithm, in order to find the vibrational modes of the beam. This set-up would be determined by its ability to produce an FFT that clearly displayed the fundamental frequencies of the vibrating beam, while also omitting any type of harmonic frequency that comes as a consequence of the wave being introduced by the beam vibration as not being a perfect sine wave. Harmonic frequencies were captured for trials with the magnet at 0 and 20 cm from the bottom of the beam. www.seas.upenn.edu /courses/belab/LabProjects/2004/be309f04r3.doc   (2439 words)

2D Frequency Domain Filtering and the 2D DFT As with the one dimensional DFT, there are many properties of the transformation that give insight into the content of the frequency domain representation of a signal and allow us to manipulate singals in one domain or the other. Since both the space and frequency domains are considered periodic for the purposes of the transforms, shifting means rotating around the boundaries. Becuase of the seperability of the transform equations, the content in the frequency domain is positioned based on the spatial location of the content in the space domain. www.owlnet.rice.edu /~elec301/Projects01/image_filt/properties.html   (210 words)

Frequency Domain Analysis Of A PCB Via The light-blue outline is the domain, and the dark blue slabs are the power and ground layers. This is the frequency-domain plot of the voltage pulses. Nearly all of the low frequency content of the incident pulse goes through the via, but much of the high frequency content is reflected. lc.cray.com /apps/xvia   (2929 words)

Frequency Domain Volume Rendering   (Site not responding. Last check: 2007-10-22) We present a new frequency domain volume rendering algorithm that replaces much of the missing depth and shape cues by performing shading calculations in the frequency domain during slice extraction. In particular, we demonstrate frequency domain methods for computing linear or nonlinear depth cueing and directional diffuse reflection. The dataset is a 96^3 voxel CT scan of a portion of a human skull mounted in a lucite head cast. graphics.stanford.edu /papers/fvr   (224 words)

Agilent Technologies | Educator's Corner - Resource Guide for Engineering Educators | Time Domain vs. Frequency Domain The three-dimensional plot of frequency, amplitude and time that shows the relationship between the time and frequency domains. It displays the amplitude of the individual frequency components vs. frequency. Depending upon the type of spectrum analyzer chosen, the phase relationships of the frequency components may or may not be preserved. www.educatorscorner.com /index.cgi?CONTENT_ID=2489   (343 words)

Time and Frequency Domain Analysis   (Site not responding. Last check: 2007-10-22) Time and Frequency Domain signals can be classified by two parameters: (Continuous or Discrete) and (Aperiodic or Periodic). The Time Domain and Frequency Domain transforms for each are related but not identical for practical evaluation. The fourier transform of the impulse response of the system is the frequency response of the system. home.earthlink.net /~roadieroger/tfdom.htm   (315 words)

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