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Topic: Frequency analysis

Related Topics

Letter frequencies

Caesar cipher

Playfair cipher

Polyalphabetic substitution

Index of coincidence

Cryptanalysis

List of famous ciphertexts

Kasiski examination

Voynich manuscript

Differential cryptanalysis

XSL attack

Enigma machine

ETAOIN SHRDLU

English orthography

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	Frequency analysis - Wikipedia, the free encyclopedia
		In mathematics, physics and signal processing, frequency analysis is a method to decompose a function, wave, or signal into its frequency components so that it is possible to have the frequency spectrum.
		In cryptanalysis, frequency analysis is the study of the frequency of letters or groups of letters in a ciphertext.
		Frequency analysis is based on the fact that, in any given stretch of written language, certain letters and combinations of letters occur with varying frequencies.
	en.wikipedia.org /wiki/Frequency_analysis (1161 words)

	[No title] (Site not responding. Last check: 2007-11-07)
		Frequency analysis is based on the fact that certain letters, and combinations of letters, appear with characteristic frequency in essentially all texts in a particular language.
		Frequency analysis was first discovered in the Arab world, and is known to have been in use by about 1000 CE.
		Frequency analysis requires a basic understanding of the language of the plaintext, as well as tenacity and some problem solving skills.
	www.informationgenius.com /encyclopedia/f/fr/frequency_analysis.html (732 words)

	frequency analysis
		The disadvantage of all these attempts to defeat frequency counting attacks is that it increases complication of both encyphering and decyphering, leading to misteaks.
		Frequency analysis requires a basic understanding of the statistics of the plaintext langauge, as well as tenacity, some problem solving skills, and considerable tolerance for extensive letter bookkeeping.
		Several of the cyphers used by the Axis were breakable using frequency analysis (eg, some of the 'consular' cyphers used by the Japanese).
	textalyser.net /frequency_analysis.html (714 words)

	FREQUENCY ANALYSIS
		The analysis of data often begins with what is called a "frequency analysis." Once the data collection process is completed, the analyst begins to explore the data, by measuring the central tendency of the data, and more importantly, the dispersion of the data around this central tendency.
		Frequency analysis is particularly useful for describing discrete categories of data having multiple choice or yes-no response formats.
		The standard error is an estimate of the potential for discrepancy between the sample mean and the population mean Because the population mean is usually unknown, the standard error cannot be calculated directly, but is estimated by dividing the standard deviation by the square root of the number of cases in the sample.
	marketing.byu.edu /htmlpages/books/pcmds/FREQ.html (2192 words)

	Hydrologic Frequency Analysis Work Group
		Two approaches for estimating the magnitude and frequency of flood discharges for ungaged watersheds are those methods based on statistical (regression) analysis of data collected at gaging stations and deterministic rainfall-runoff models that use rainfall input and algorithms to convert rainfall excess to flood discharges.
		Frequency analyses are then performed on the simulated peak flows to determine design discharges such as the 1-percent chance flood.
		The flood frequency workgroup voted to recommend that the report "Evaluation of Flood Frequency Estimates for Ungaged Watersheds," by Wilbert Thomas, Mike Grimm and Richard McCuen be considered by the Hydrology sub-Committee for adoption as guidelines for performing ungaged flood frequency analysis.
	water.usgs.gov /wicp/acwi/hydrology/Frequency/Ungaged_rpt.html (6155 words)

	LAB745 - Frequency Analysis of Jitter
		Our goal is to measure the rms jitter of the modulation spectrum in the frequency domain and to match that with the rms jitter of the time domain waveform.
		The square root of the area parameter is the rms jitter of the frequency spectrum.
		In the first example the burst duration is 1 ms and the burst repetition period is 2 ms for a duty cycle of 50%.
	www.lecroy.com /tm/library/labs/lab745?menuid=2 (795 words)

	Linear Dynamic Analysis Types: Frequency Response (Modal Superposition) Analysis
		Frequency response (modal superposition) analysis determines the steady-state operation of a machine, vehicle or process equipment design subjected to continuous harmonic loading.
		As compared to linear transient stress analyses, frequency response (modal superposition) analysis provides an easy, quick method in which the only inputs are a constant frequency and amplitude.
		For example, this analysis type could be used to determine the vibration effects of a washing machine with an unbalanced load or a bent wheel on a vehicle.
	www.algor.com /products/analysis_types/linear_dynamics/frequency_response.asp (108 words)

	Frequency analysis - Metaweb (Site not responding. Last check: 2007-11-07)
		Frequency analysis is the way to crack simple cryptosystems like the caesar cipher.
		The most common letters in normal English sentences are E, T, A, O and I; and the least common are Z, Q, X, J, and K. Therefore, if the letter P occurs most often in the ciphertext you are looking at, it is most likely that it is one of the first group of letters.
		Once a frequency table is built from the ciphertext, a cryptanalyst can begin guessing which letters match with which.
	www.metaweb.com /wiki/wiki.phtml?title=Frequency_analysis (282 words)

	Chap VI
		This is a form of labeled-line, or "place," theory of pitch perception in which the locus of maximal vibration along the cochlear spiral determines the perceived pitch by activating a specific small group of nerve fibers.
		There is a systematic shift in the locus of maximal vibration from the apex toward the base as the frequency of a pure tone stimulus is raised.
		The frequency to which a fiber is most sensitive is referred to as the characteristic frequency (CF).
	www.neurophys.wisc.edu /h%26b/textbook/chap-6.html (3134 words)

	Log-Linear Analysis of Frequency Tables
		Correspondence analysis is a descriptive/exploratory technique designed to analyze two-way and multi-way tables containing some measure of correspondence between the rows and columns.
		In this table, the proportions of the marginal frequencies are reflected in the individual cells.
		If the model is appropriate for the table, then all residual frequencies should be "random noise," that is, consist of positive and negative values of approximately equal magnitudes that are distributed evenly across the cells of the table.
	www.statsoft.com /textbook/stloglin.html (1647 words)

	Historical record of flooding on the Mohawk River, New York (Site not responding. Last check: 2007-11-07)
		We do this by looking at the frequency of flooding, the changes in the periods of flooding, and the general hydrology of the basin as indicated by the record of discharge.
		Analysis of the drainage basin can be useful in predicting whether the area should prepare for a higher frequency of destructive storms and their economic and social consequences.
		Some important patterns with respect to flood frequency through time are revealed in the plot of high and low flow annual events (Figures 5 and 6) and three distinct patterns of flooding may be evident.
	zircon.geology.union.edu /Mohawk_river/Mohawk_Flood (5827 words)

	Letter Frequencies
		In other words, if the sender has tried to disguise a letter by replacing with a different letter, you can still recognise the original letter because the frequency characteristics of the original letter will be passed on to the new letters.
		To apply frequency analysis, you will need to know the frequency of every letter in the English alphabet, or the frequency of letters in whichever language the sender is using.
		Please note, these frequencies are averages, and E will not always constitute 12.7 % of all the letters in a text, and may not even be the most common letter.
	www.simonsingh.net /The_Black_Chamber/frequencyanalysis.html (241 words)

	Frequency Analysis
		The problem lies in the fact that the frequency with which letters occur in English is remarkably consistent.
		Frequency analysis involves going through a piece of text, plain or encoded, and seeing how many times each letter (or symbol) appears.
		To demonstrate the regularity of this frequency pattern, I have taken the first 1000 letters of two separate texts and counted how many times each letter appears.
	richardbowles.tripod.com /excel/codes/freqanal.htm (1130 words)

	Word Frequency Text Analysis (Site not responding. Last check: 2007-11-07)
		The Word Profiler compares all the words in a text with two word frequency lists, it provides a visual profile of the distribution of these words in a text by printing the different frequency bands in different colours.
		This analysis contrasts words found in the 1 - 1000 (K1) word families and the second Most Frequent 1001 - 2000 (K2) word family lists found in Academic English, and were developed by Paul Nation of the School of Linguistics and Applied Language Studies at Victoria University of Wellington, New Zealand.
		You can use these Text Analysis functions to provide a measure of text readability by passing texts that you use at different levels to be compared against the word frequency lists.
	www.edict.com.hk /textanalyser (1059 words)

	FFT Properties
		It is a frequency spectrum of the signal with frequency of 1Hz and amplitude of 1V.
		If the frequency of the signal falls between two lines, and we do not apply zero padding (spectrum oversampling) it is almost impossible to say what is the actual frequency of that signal or the actual amplitude.
		When sampling your data, you should make sure that the sampling frequency is higher then two times the highest frequency that is physically present in the process being sampled, or an anti-aliasing filter is mandatory or you will not know what are you looking at.
	www.teemach.com /FFTProp/FFTProperties/FFTProperties.htm (3940 words)

	Publications of Brian C (Site not responding. Last check: 2007-11-07)
		Roberts and B.C.J. Moore, The influence of extraneous sounds on the perceptual estimation of first-formant frequency in vowels under conditions of asynchrony, J.
		Furukawa and B.C.J. Moore, Dependence of frequency modulation detection on frequency modulation coherence across carriers: Effects of modulation rate, harmonicity and roving of the carrier frequencies, J.
		Micheyl, B.C.J. Moore and R.P. Carlyon, The role of excitation-pattern cues and temporal cues in the frequency and modulation-rate discrimination of amplitude-modulated tones, J.
	hearing.psychol.cam.ac.uk /Biogs/bmpubs.html (8253 words)

	Amazon.com: Books: Foundations of Time-Frequency Analysis (Applied and Numerical Harmonic Analysis) (Site not responding. Last check: 2007-11-07)
		For many years time-frequency analysis has been pursued only in engineering, but recently, and with the development of wavelet theory, it has emerged as a thriving field of applied mathematics.
		Important principles are (a) classical Fourier analysis as a tool that is central in modern mathematics, (b) the mathematical structures based on the operations of translation and modulations (i.e.
		While Gabor analysis is described on equal footing with wavelets in the early literature on the subject (in the late 80's) the book market on wavelets exploded, while no "serious" (from a mathematician's point of view) introduction to Gabor analysis was available.
	www.amazon.com /exec/obidos/tg/detail/-/0817640223?v=glance (1217 words)

	Web Frequency Indexer: Help (Site not responding. Last check: 2007-11-07)
		A frequency index is a list of words in a text, with the number of times each word occurs (its 'raw' frequency in the text).
		Frequency lists are used by language teachers to prepare teaching materials for the most commonly occurring words in a text or a set of texts (for example, the 'top 200' words).
		Frequency lists are also used by literary analysts and computational linguists.
	www.georgetown.edu /faculty/ballc/webtools/web_freqs_help.html (620 words)

	A novel sensitive approach for frequency analysis of measles virus-specific memory T-lymphocytes in healthy adults with ...
		A novel sensitive approach for frequency analysis of measles virus-specific memory T-lymphocytes in healthy adults with a childhood history of natural measles -- Nanan et al.
		The median frequency of MV-specific T-cells was 0·35%
		(a) To analyse T-cell subset frequencies by IFN-
	vir.sgmjournals.org /cgi/content/full/81/5/1313 (3235 words)

	Flood Frequency Analysis (Site not responding. Last check: 2007-11-07)
		Flood Frequency Analysis, the determination of flood flows at different recurrence intervals, is a common problem in hydrology.
		Continuous hydrologic simulation is a valuable tool to determine flood frequencies in ungaged watersheds and in gaged watersheds that have short streamflow records or are heavily regulated.
		Since hydrologic simulation models the rainfall-runoff relationship in the basin, it can also be used to check the validity of the probabilistic distribution selected for gaged, unregulated watersheds with long stream flow records.
	www.hydrocomp.com /ffreq.html (561 words)

	2. Time-Frequency Analysis
		In many applications such as speech processing, we are interested in the frequency content of a signal locally in time.
		Information which is localized in time such as spikes and high frequency bursts cannot be easily detected from the Fourier Transform.
		That is, the ``frequency resolution'' of this analysis is
	www.engmath.dal.ca /courses/engm6610/notes/node3.html (597 words)

	ENGnetBASE: Engineering Handbooks Online
		Flood Frequency Analysis fills this gap by presenting many of these distributions and estimation procedures in a unified format within a single, self-contained book.
		Focusing on distribution families popular within the hydrologic community, the authors discuss three parameter estimation methods for each distribution: the method of moments, the maximum likelihood method, and the method of probability weighted moments.
		With other books on the subject either limited in scope or seriously outdated, Flood Frequency Analysis provides the ideal vehicle for practicing hydrologists and engineers to explore and apply the latest methods and research results, and in doing so, contribute to the advancement of the field.
	www.engnetbase.com /ejournals/books/book_summary/summary.asp?id=547 (231 words)

	Analysis - Open Encyclopedia (Site not responding. Last check: 2007-11-07)
		An analysis is a critical evaluation, usually made by breaking a subject (either material or intellectual) down into its constituent parts, then describing the parts and their relationship to the whole.
		aura analysis - study of bodily auras and energy fields
		This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title.
	open-encyclopedia.com /Analysis (130 words)

	Codebreaking- Frequency Analysis - Codes & Cyphers
		Determining the frequency of letters was previously a tedious task; however, in the modern era, computers and software are used to calculate the statistics very rapidly.
		One of the most frequently used words in the English language is "the".
		For example, as a tool for website building, it can analyze the text of the page, and indicate the most frequently used words, which might be good for picking out keywords to reference.
	www.bellaonline.com /articles/art33273.asp (583 words)

	A Pictorial Introduction to Fourier Analysis/Synthesis (Site not responding. Last check: 2007-11-07)
		In the late 1960's, Blakemore and Campbell (1969) suggested that the neurons in the visual cortex might process spatial frequencies instead of particular features of the visual world.
		In English, this means that instead of piecing the visual world together like a puzzle, the brain performs something akin to the mathematical technique of Fourier Analysis to detect the form of objects.
		While this analogy between the brain and the mathematical procedure is at best a loose one (since the brain doesn't really "do" a Fourier Analysis), whatever the brain actually does when we see an object is easier to understand within this context.
	psych.hanover.edu /Krantz/fourier (156 words)

	Reasons for Frequency Response Analysis (Site not responding. Last check: 2007-11-07)
		Frequency response analysis is important to us for two primary reasons.
		For example, in the design of an audio 3-way loudspeaker system, we would like to direct low frequency signals to the woofers, high frequency signals to the tweeters, and mid-frequency signals to the mid-range speakers.
		Therefore we would need a circuit that is capable of passing certain frequencies of a signal and rejecting others.
	www.ee.duke.edu /~cec/final/node102.html (165 words)

	Time-Frequency Analysis of Chaotic Systems (ResearchIndex) (Site not responding. Last check: 2007-11-07)
		5 The measure of chaos by numerical analysis of the fundamenta..
		1 Wavelet analysis of the asteroidal resonant motion (context) - Michtchenko, Nesvorny - 1996
		1 Local frequency analysis of chaotic motion in multidimension..
	citeseer.ist.psu.edu /546385.html (446 words)

	[No title] (Site not responding. Last check: 2007-11-07)
		A tool to help crack letter-substitution ciphers by making a table of the frequencies of the letters in a sample of ciphertext.
		A histogram to the left shows the relative frequency of each of the letters in the text.
		Once you have identified which letters have been substituted a few key letters such as "A", "E", "O" and "T", then even a partial deciphering of the message should enable you to guess the rest.
	www.wiley.com /college/mat/gilbert139343/java/java11_s.html (174 words)

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