| 释义 |
frequency|ˈfriːkwənsɪ|
[ad. L. frequentia: see prec. and -ency.]
†1. The state or condition of being crowded; also concr. a numerous assembly, concourse, crowd.
1553–87Foxe A. & M. (1596) 196/1 The king commanded all the..prelats of the church to be called in a great solemn frequencie. 1570–6Lambarde Peramb. Kent (1826) 201 To Pinnendene Heath..expert men of this Shyre..came in great frequencie. 1601R. Johnson Kingd. & Commw. (1603) 114 Nothing doth better temper the aire of any place than the frequency of inhabitants. 1644Milton Judgm. Bucer (1851) 290 He was for two years chief Professor..with greatest frequency and applause of all learned and pious men. 1723State of Russia I. 209 The frequency of People at Moskow was extraordinary on this Occasion.
†2. The fact of occurring at short distances apart; numerousness. Obs.
1659B. Harris Parival's Iron Age 45 The enemies army could not enter, in regard of the frequency of great rivers.
†3.
a. The constant use or repetition of (something); frequent practice. Obs.
1615J. Stephens Satyr. Ess. 69 The patronage of Plebeians..The frequencie of which custome made Nobilitie famous. 1682Norris Hierocles 14 Neither does this precept of honouring an Oath forbid us Perjury only, but also frequency of Swearing. 1688S. Penton Guardian's Instr. 59 Oblige him to frequency of Writing Home. 1785S. Fielding Ophelia II. xviii, The frequency of vice had deadened her sense of it.
†b. Frequent intercourse, familiarity with (a person); constant attendance at (a place). Obs.
1642Howell For. Trav. (Arb.) 21 The greatest bane of English Gentlemen abroad, is too much frequency and communication with their own Countrey-men. 1680Ld. Capel Sp. Ho. Com. 26 Oct. in Collect. Poems 179 Who by his frequency at the Palace, had seemed rather one of the Family.
4. a. The fact of occurring often or being repeated at short intervals. Of the pulse: Rapidity.
1641Ld. J. Digby Sp. Ho. Com. 19 Jan. 20 The frequencie of Parliament is most essentially necessary. 1696tr. Du Mont's Voy. Levant 226 Earthquakes..there happen'd four in one day..Nor does their frequency make 'em less dreadful. 1732Arbuthnot Rules of Diet 272 They increase the Strength and Frequency of the Pulse. 1766Goldsm. Vic. W. vii, I began..to be displeased with the frequency of his return. 1836Hor. Smith Tin Trumpet (1876) 271 The diminished frequency of wars. 1883A. Jessopp in 19th Cent. XIII. 259 The ghastly frequency of the punishment of death tended to make people savage and bloodthirsty.
b. Physics, etc. The rate of recurrence of any regularly repeated event, e.g. a vibration; the number of times that it occurs in a second or other assumed unit of time. In Telecommunications, the number of cycles per second of the carrier wave of a transmission; hence loosely, a frequency band, a channel. Also, a signal, or a component of a signal, having a frequency of a certain value or in a certain range.
1831Brewster Nat. Magic ix. (1868) 287 The pitch or frequency of vibration constituting the note. 1835Rep. Brit. Assoc. 1834 315 The colour of the light is supposed to be determined by the frequency of the ethereal vibrations, or by the length of the wave. 1881Nature No. 616. 359 If the notes c′ and d{pp} are sounded together, their frequencies being in the ratio 8:9. 1893Times 11 May 6/1 Alternating currents of high frequency. 1896W. G. Woollcombe Pract. Work Physics iii. 69 Take the average of these numbers for each fork to represent the ratio of their frequencies. 1943C. L. Boltz Basic Radio viii. 133 A succession of such circuits will attenuate the higher frequencies so much that their amplitude is negligible. 1948P. M. Morse Vibration & Sound (ed. 2) vi. 226 Corresponding to the physical quantities intensity and frequency are the physiological..quantities loudness and pitch. 1958Radio Times 14 Feb. 3/2 To make sure that the BBC keeps strictly to the frequencies (or wavelengths), both in sound and television broadcasting, allotted to it by international agreement. 1958‘N. Shute’ Rainbow & Rose i. 7 We've been monitoring their frequency. 1962Which? Feb. 41/2 Sound travels in the form of waves—rather like radio waves, but of a far lower frequency. Ibid. 42/1 The other VHF radios would reproduce frequencies higher than 4,200 cycles per second, but only at a lower volume. 1971Daily Tel. 7 Jan. 14/6 Enough radio frequencies could be made available on the medium wave to satisfy commercial radio and the existing BBC local stations.
c. Statistics. The number of times an event or character occurs in a given sample; also (the relative frequency or proportionate frequency), this number expressed as a proportion of the total possible number of occurrences.
1854G. Boole Invest. Laws of Thought xvii. 268 For if we substitute..we shall form the expression of that event whose probability constitutes the numerator of c, and the ratio of the frequency of this event to that of the former one..will give the value of c. 1857Phil. Mag. 4th Ser. XIV. 61, I have commenced collecting statistics showing the relative frequency with which the different simple letters, and various compounds of simple letters, occur in the English language. 1875F. Galton in Ibid. XLIX. 37 We may work backwards, and, from the relative frequency of occurrence of various magnitudes, derive a knowledge of the true relative values of those magnitudes, expressed in units of probable error. 1937L. H. C. Tippett Methods of Statistics (ed. 2) i. 28 Frequencies and proportionate frequencies underlie nearly all methods of statistical representation. 1943M. G. Kendall Adv. Theory Statistics I. vii. 165 The second approach seeks to define probability in terms of the relative frequency of events. 1950W. Feller Introd. Probability Theory I. i. 18 The frequency of multiple aces in the hands at bridge. 1955M. Loève Probability Theory i. 5 In a game of dice..‘double-six’ occurs about once in 36 times, that is, its observed frequencies cluster about 1/36. The number 1/36 is a permanent numerical property of ‘double-six’ under the conditions of the game, and the observed frequencies are to be thought of as measurements of the property. 1965A. H. Roberts Statistical Ling. Anal. Amer. Eng. v. 60 These 8,103 words had a total frequency of 10,503,788 or 2/3 of the total frequencies of occurence.
d. Ecol. A measurement of the way individuals of a species are distributed in a community.
1913C. Raunkiaer in Jrnl. Ecol. I. 24 Each species acquires the same degree of frequency as in a shoot-counting method if the frequency be expressed in whole numbers from 1 to 5. 1921Jrnl. Ecol. IX. 97 If we know the absolute degree of frequency of a species (that is the number of individuals belonging to one species growing on a large area Y) we can calculate the probable occurrence on every area (y) which is smaller than Y. 1932Ecol. Monogr. ii. 478 Frequency is concerned with the uniformity with which the plants of a species are distributed throughout a plant community. Ibid. 479 The percentage is called the ‘frequency index’ of the species. 1964K. A. Kershaw Quantitative & Dynamic Ecology i. 16 The frequency of a species is a measure of the chance of finding it with any one throw of a quadrat in a given area. Thus, if a species has a frequency of 10 per cent then it should occur once in every ten quadrats examined.
5. attrib. and Comb., as (sense 4 b) frequency characteristic, frequency correction, frequency-dependent adj., frequency discriminator, frequency divider, frequency doubler, frequency indicator, frequency meter, frequency multiplier, frequency-multiplying ppl. adj., frequency raiser, frequency range, frequency-selective adj., frequency teller, frequency transformer; (sense 4 c) frequency-count.
1926*Frequency characteristic [see frequency response]. 1957BBC Handbk. 49 Sound circuits have to be equalized in frequency characteristic.
1962A. Nisbett Technique Sound Studio i. 17 (caption) Between studio, continuity and transmitter there may be..switching centres, boosting amplifers and *frequency correction networks on land⁓lines, etc. Ibid. 254 Frequency correction, the change in the frequency characteristics of a signal which is required to restore it to its original form.
1956J. Whatmough Language v. 73 The 20,000 most frequently occurring words (as ascertained by previously made *frequency counts).
1962W. B. Thompson Introd. Plasma Physics ii. 14 Thus the plasma appears as a dielectric with a *frequency-dependent dielectric coefficient.
1935*Frequency discriminator [see discriminator 2 b]. 1943Gloss. Terms Telecomm. (B.S.I.) 73 Frequency discriminator, a device for producing an output voltage approximately proportional to the deviation of frequency of a signal from a predetermined value. 1944Electronic Engin. XVII. 196 The frequency discriminator..has only recently been finding its place in commercial radio receivers in this country.
1938S. R. Roget Dict. Electr. Terms (ed. 3) 141/1 *Frequency divider. 1952Terman & Pettit Electronic Measurem. (ed. 2) v. 196 By means of a chain of subharmonic generators (frequency dividers), one obtains frequencies of 10,000 cycles, 1000 cycles, and 100 cycles which have the same degree of precision as the standard frequency.
1924S. R. Roget Dict. Electr. Terms 94/2 *Frequency doubler. 1950P. Parker Electronics xi. 374 A class C amplifier is sometimes used as a frequency doubler, by tuning the tank circuit to the second harmonic of the signal frequency.
1906J. A. Fleming Princ. Electr. Wave Telegr. i. 42 One well-known form of *frequency indicator is that due to Mr. Campbell.
Ibid., In addition to the voltmeters and ammeters..a *frequency meter ought to be provided. 1957B. L. Ginzton Microwave Measurem. viii. 389 The frequency of the unknown signal can be measured with moderate accuracy by an instrument called the heterodyne frequency meter.
1933K. Henney Radio Engin. Handbk. xviii. 462 Present practice favors the use of static *frequency multipliers where it is desired to use an alternator of comparatively low frequency. 1966McGraw-Hill Encycl. Sci. & Technol. V. 515/1 A lower frequency is generated in a crystal-controlled oscillator..and a frequency multiplier is employed to obtain the high frequency desired.
1962Simpson & Richards Junction Transistors xviii. 457 Using a *frequency-multiplying circuit to increase both the carrier and deviation frequencies.
1893Jrnl. Soc. Arts 5 May 624/1 We want..a *frequency-raiser.., which shall transform the frequency, even as the induction-coil transforms the voltage. 1926G. G. Blake Hist. Radio Telegr. 234 The main object of the foregoing frequency raisers has been to obtain an increase of frequency from comparatively low frequency alternators.
1936Summ. Doct. Diss. N.W. Univ. IV. 180 Within any response-band the glottal note was lowered as the supply-tube was lengthened, the successive response⁓bands, or optima, covering similar *frequency-ranges. 1962Which? Feb. 41/2 We found personal radios had a limited frequency range, from about 220 to 3,900 cycles per second.
1946Nature 23 Nov. 759/1 *Frequency-⁓selective attenuation by interstellar matter. 1962A. Nisbett Technique Sound Studio 245 Marked acoustic colouration in a studio may be due..to frequency-selective excessive absorption of sound.
1906J. A. Fleming Princ. Electr. Wave Telegr. i. 43 Many other forms of *frequency teller have been developed for practical use in connection with transformer working. 1941S. R. Roget Dict. Electr. Terms (ed. 4) 144/2 Frequency teller, a name used, particularly in radio-communication for a frequency meter.
1893Jrnl. Soc. Arts 5 May 624/1 The *frequency-transformers hitherto used in the laboratory for purposes of research..are not practical for electric-lighting purposes. 1940Chambers's Techn. Dict. 355/2 Frequency transformer, a static piece of apparatus (e.g. a transformer or mercury-arc convertor) which receives power at one frequency and delivers it at another frequency.
6. Special comb.
a. (sense 4 b) frequency band = band n.2 14; frequency changer, a machine, circuit, or component that changes an alternating current of one frequency into one of another frequency; spec. in a superheterodyne receiver, the circuit or component that combines the incoming signal with that from the local oscillator to produce the intermediate frequency; frequency converter, a frequency changer; frequency distortion, distortion of a signal in which components of different frequencies are amplified or attenuated to different extents; frequency diversity, the use of channels of different frequencies in a diversity system of communication; frequency response, the relationship between the output–input ratio of a device or system designed to transform or transmit oscillatory signals and the frequency of the signal; frequency shift, used attrib. (also absol.) to designate a method of radio telegraphy in which the carrier frequency takes either of two approximately equal values according as the signal is a ‘space’ or a ‘mark’; frequency spectrum, the entire range of frequencies of electromagnetic waves, sound waves, etc.; also, the distribution of the energy of a wave-form among its different Fourier components. Also frequency modulation.
1922Bell Syst. Techn. Jrnl. July 117 The method consists in analyzing the speech waves as impressed on a condenser transmitter, using a tuned circuit to transmit narrow frequency bands of energy. 1929J. H. Morecroft Elem. Radio Communication iii. 82 The normal frequency band for broadcasting purposes is..from 550 to 1500 kilocycles. 1956Tibbs & Johnstone Frequency Modulation Engin. (ed. 2) v. 106 Of the three major frequency bands, the v.h.f. band has been developed rapidly.
1902Sheldon & Mason A.C. Machines vii. 157 The synchronous motor necessary to drive the frequency changer. 1965BBC Handbk. 116 For best results on short waves, a receiver should incorporate a tuned radio-frequency amplifier preceding the frequency-changer stage.
1909Cent. Dict. Suppl. I. 292/3 Frequency-converter. 1912Bedell & Pierce Direct & Altern. Current Man. (ed. 2) ix. 291 The usual form of frequency changer or frequency converter consists merely of an induction motor and a separate driving motor. 1957A. C. Clarke Deep Range (1968) xii. 106 This was a simple enough task for the sub's frequency converters; if he wished, Franklin could tune in to any sounds from almost a million cycles a second down to vibrations as sluggish as the slow opening of an ancient, rusty door. 1959K. Henney Radio Engin. Handbk. (ed. 5) ix. 9 Semiconductor diodes are used over a very wide frequency range (a-f to microwave) as frequency converters.
1932F. E. Terman Radio Engin. v. 121 Frequency distortion tends to be greater as the amplification per stage is increased. 1962A. Nisbett Technique Sound Studio xii. 214 Quite severe frequency distortion can and does go practically unnoticed by 99% of the general public.
1931Proc. Inst. Radio Engin. XIX. 531 Frequency diversity is effective due to the difference of fading times for frequencies differing by as little as several hundred cycles. 1964Electronics Weekly 8 July 7/4 Frequency diversity is a standard feature of most microwave links... If fading occurs in the ‘working’ channel the telephone traffic..is automatically switched to the other channel.
1926Jrnl. Inst. Electr. Engin. LXIV. 1023/2 Perfect reproduction of the originating wave-form necessitates a system with a uniform frequency response or frequency characteristic at all volume-levels. 1932C. L. Boltz Everyman's Wireless xi. 225 The frequency-response curve..shows a very severe resonance at just over 500 cycles. 1971Which? Jan. 19/1 Almost all microphones had at least as good a frequency response as the tape recorders they were to be used with.
1944Electronics Nov. 126/2 The bandwidth required by frequency-shift transmission is no greater than that required by the carrier make and break system. Ibid. 127/3 Frequency shift can result in a much lower bandwidth than carrier make-break. 1959Chambers's Encycl. XI. 471/1 A method of keying which is extensively employed with teleprinters is that known as frequency-shift (or carrier shift), in which the sender radiates continously.
1955F. E. Terman et al. Electronic & Radio Engin. (ed. 4) xvii. 591 When the instantaneous frequency of a frequency-modulated wave is varied in a more complex manner..the frequency spectrum becomes very complicated. 1962Rep. Comm. Broadc. 1960 5 in Parl. Papers 1961–2 (Cmnd. 1753) IX. 259 The division by international agreement of the frequency spectrum into bands allocated to particular services forms part of the International Radio Regulations. 1962A. Nisbett Technique Sound Studio 269 Scale, division of the audio frequency spectrum by musical intervals (i.e. frequency ratios). 1968C. W. McMullen Commun. Theory Princ. i. 10 The shape and dimensions of the pulse signal determine the frequency spectrum.
b. (sense 4 c) frequency curve, a frequency diagram in the form of a continuous curve, with the variable taking any of a continuous range of values for each member of a large population; frequency diagram, a diagram in which frequency of occurrence is plotted against the value of the variable; frequency distribution, a classification of the members of a population according to the value assumed for each member by some variable; a diagram or table showing the frequency with which a variable takes each of its possible values; frequency polygon, a frequency diagram containing a (small) finite number of points that are joined to form a line composed of a number of straight segments.
1893K. Pearson in Nature 26 Oct. 615/2 The asymmetrical character of certain frequency curves in physical and biological measurements. 1911G. U. Yule Introd. Theory Statistics vi. 76 Such an ideal limit to the frequency-polygon or histogram is termed a frequency-curve. 1932J. S. Huxley Probl. Rel. Growth vii. i. 210 The frequency-curve for female body-length is unimodal.
1925R. A. Fisher Statistical Methods ii. 37 Fig. 4 is a frequency diagram illustrating the distribution in stature of 1375 women. 1931L. H. C. Tippett Methods of Statistics ii. 23 Frequency diagrams are useful as giving a visual impression of the characteristics of a sample.
1895K. Pearson in Phil. Trans. R. Soc. A. CLXXXVI. 412 A method is given of expressing any frequency distribution by a series of differences of inverse factorials with arbitrary constants. 1924Whittaker & Robinson Calc. of Observations viii. 165 The type of frequency distribution which is most familiar to the worker in experimental science is the distribution of the measures obtained by repeated measurements of the same observed quantity. 1948New Biol. IV. 29 We cannot interpret the change in mean until we have examined the type of scatter of the individual heights around the mean, that is what the statistician describes as the frequency distribution of heights. 1965A. H. Roberts Statistical Ling. Anal. Amer. Eng. v. 44 Table 3 and Appendix VIII show the joint frequency distribution of word length by syllable and phoneme number.
1897K. Pearson Chances of Death I. 273 If the tops of these lines be joined we obtain a frequency polygon. 1966E. B. Mode Elem. Probability & Statistics ix. 123 The frequency polygon..gives a picture of the way in which frequency of occurrence varies over the complete gamut of values. |