EN 61120-4-1992 en Digital Audio Tape Recorder Reel-to-Reel System Using 6 3 mm Magnetic Tape for Professional Use Part 4 Magnetic Tape Properties Definitions and Methods of Measur.pdf

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1、3404583 008290b 311 EUROPEAN STANDARD NORMEEUROPENNE EUROPISCHE NORM EN 61120-4 August 1992 UDC 621.396.7 : 681.846.7.083.8 : 681.32 : 621.317.08/: 620.1 Descriptors: Sound recording, sound readers, magnetic tapes, measurements, properties English version Digital audio tape recorder reel-to-reel sys

2、tem, using 6,3 mm magnetic tape, for professional use Part 4: Magnetic tape properties: definitions and methods of measurement (IEC 1120-4 : 1992) Sytme denregistrement bande audionumrique, bobine bobine, utilisant une bande magntique de 6,3 mm, usage professionnel Partie 4: Proprits des bandes mesu

3、re Digitales Tbnbandgert Spulensystem mit Magnetband 6,3 mm fr Studioanwendung Teil 4: Eigenschaften der Magnetbnder - Begriffe und MeBverfahren magntiques: dfinitions et mthodes de (IEC 1120-4 : 1992) (CE1 1120-4 : 1992) This European Standard was approved by CENELEC on 1992-06-16. CENELEC members

4、are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard wit,hout any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application

5、to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has

6、the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European C

7、ommittee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B- 1050 Brussels O 1992 Copyright reserved to CENELEC members Ref. KO. EN 61120-4 : 1992 E = 3404583 0082907 258 Pag

8、e 2 EN 61120-4 : 1992 Foreword The text of document 60A(C0)139, as prepared by Sub-committee 60A: Sound recording, of IEC Echnical Committee No. 60: Recording, was submitted to the IEC-CENELEC parallel vote in September 1991. The reference document was approved by CENELEC as EN 61120-4 on 16 June 19

9、92. The following dates were fixed: - latest date of publication of an identical national standard (dop) 1993-06-01 - latest date of withdrawal of conflicting national standards (dow) 1993-06-01 Annexes designated normative are part of the body of the standard. In this standard, annex ZA is normativ

10、e. W 3404543 0082908 194 W Page 3 EN 61120-4 : 1992 CONTENTS Page Clause Scope . Normative references Definitions 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.1 O Flux transitions . Physical recording density Test density Recording current wave form . Recording current peak-to-peak value . Recommended reco

11、rding current . Reference recording current . Test recording current Average signal level . Standard reference level Technical requirements and test conditions 4.2 Mechanical characteristics of test equipment . 4.3 Electrical characteristics of test equipment . 4.4 Reference tapes 4.5 Condition of t

12、he tape to be tested . 4.1 Standard atmospheric conditions . Electrical parameters to be measured 5.1 Resolution . 5.2 Overwrite characteristic 5.3 Dropouts . 5.4 Relative average signal level to noise ratio . 5.5 Characteristics of the sub-tracks in case of bias-recording Recommended parameters to

13、be described in published data for professional digital audio tapes Mechanical parameters to be measured Figures . Annex A (informative) . Name and address of the manufacturer of primary standard Annex ZA (normative) Other international publications quoted in this standard with the references of the

14、 relevant European publications. . I EC reference tapes . 4 4 5 5 5 5 5 5 5 6 6 6 6 6 6 6 7 7 8 8 8 9 9 9 9 10 10 11 13 14 3404583 0082909 O20 Page 4 EN 61120-4 : 1992 DIGITAL AUDIO TAPE RECORDER REEL-TO-REEL SYSTEM, USING 6,3 mm MAGNETIC TAPE, FOR PROFESSIONAL USE Part 4: Magnetic tape properties:

15、definitions and methods of measurement 1 Scope This pari of IEC 1120 applies to methods of measurement for the properties of magnetic tapes used in digital audio reel-to-reel recording and reproducing systems using 6,3 mm magnetic tape for professional use. 2 Normative references The following stand

16、ards contain provisions which, through reference in this text, constitute provisions of this pari of IEC 1120. At the time of publication of this standard, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this pari of IEC 1120 are encourage

17、d to investigate the possibility of applying the most recent editions of the standards listed below, Members of IEC and IS0 maintain registers of currently valid International Standards. IEC 50(806): 1975, International Electrotechnical Vocabulary (IEV) - Chapter 806: Recording and reproduction of s

18、ound and video. IEC 94-4: 1986, Magnetic tape sound recording and reproducing systems - Part 4: Mechanical magnetic tape properties. IEC 94-5: 1988, Magnetic tape sound recording and reproducing systems - Fart 5: Elec- trical magnetic tape properties. IEC 386: 1972, Method of measurement of speed fl

19、uctuations in sound recording and reproducing equipment, Amendment No. 1 (1988). IEC 1 120-1 : 1991, Digital audio tape recorder reel-to-reel system, using 6,3 rnrn magnetic tape, for professional use - Part I: General requirements. IEC 11 20-2: 1991, Digital audio tape recorder reel-to-reel system,

20、 using 6,3 mm magnetic tape, for professional use - Part 2: Format A. IEC 11 20-3: 1991, Digital audio tape recorder reel-to-reel system, using 6,3 mm magnetic tape, for professional use - Part 3: Format B. IEC 1 120-5: 199x, Digital audio tape recorder reel-to-reel system, using 6,3 mm magnetic tap

21、e, for professional use - Part 5: Reels. m 3404583 0082910 842 m Page 5 EN 61120-4 : 1992 3 Definitions The following definitions apply for the purposes of this part. 3.1 flux transitions: Flux transitions are those parts along the tape where the mag- netization reverses its direction. 3.2 physical

22、recording density: Physical recording density is the number of recorded flux transitions per unit length of track (flux transitions per millimetre). 3.3 test density: For the purpose of testing the tape in accordance with this part the physical recording density shall be 336 flux transitions per mm

23、(test density A) and 1 008 flux transitions per mm (test density B) with tolerances of f0,l %. The corresponding nominal squarewave frequencies Fa and F, are 32 kHz and 96 kHz respectively at 19,05 cmis, and 64 kHz and 192 kHz respectively at 38,l cm/s. 3.4 recording current wave-form: The recording

24、 current to be used shall conform to the wave-form as given in figure 1. 3.5 recording current peak-to-peak value: Recording current peak-to-peak values are specified as follows: , /pp = /w, + /w* where Iw, is the actual current at f = 2 Tl and (see figure 1) T2 /w2 is the actual current at f = T, +

25、 - 2 3.6 recommended recording current: - When the recording current is increased in amp tude from zero at test density B, the playback signal level (r.m.s. value) will increase to a maximum and then decrease. - The smaller peak-to-peak value of the recording current which causes an output signal le

26、vel equal to -0,s dB of the maximum level is called the 0,5 dB below saturation current (see figure 2). - The larger peak-to-peak value of the recording current which makes an output signal level equal to -0,s dB of the maximum level is called the 0,5 dB above saturation current (see figure 2). - Th

27、e recommended recording current shall be calculated from the value of 0,5 dB below saturation current and that of 0,s dB above saturation current as follows: W 3404593 0082913 789 Page 6 EN 61120-4 : 1992 - Recommended recording current is: where In, is the recommended recording current C = 0,5 dB a

28、bove saturation current value 6 = 0,5 dB below saturation current value 3.7 reference recording current: Reference recording current (peak-to-peak value) is the nominal recording current of the reference tape. 3.8 test recording current: The recording current to be used for testing the tape in accor

29、dance with this pari shall have a peak-to-peak value equal to reference recording current . 3.9 average signai levei: Average signal level is the average value of the r.m.s. output voltages over at least 76 mm along the tape, which has been recorded under the condi- tions of 3.3 and using the test r

30、ecording current for both density A and B. 3.10 standard reference level: Defined as the average signai level (r.m.s. value) obtained by recording the reference tape, using the test recording current. 4 Technical requirements and test conditions 4.1 Standard atmospheric conditions Ambient temperatur

31、e: 20 OC f 5 OC Relative humidity: 60 o/o f 15 % Before commencing measurements, the test specimen shall have reached equilibrium with its environment. 4.2 4.2.1 Tape speed Mechanical characteristics of test equipment Tape transports shall be capable of operating at the rated speeds of 19,05 cm/s an

32、d 38,l cm/s with a tolerance of k0,2 Yo. The short term tape speed fluctuations shall be not more than 0,1 Yo when measured in accordance with IEC 386 and its Amendment No. 1, method 2. 4.2.2 Tape width Tape transports shall be capable of accommodating and running the tapes of width 6,3 mm, conformi

33、ng to tolerances specified in IEC 11 20-1. 3404583 0082912 615 = Page 7 EN 61120-4 : 1992 4.2.3 Tape guides Tape guides shall ensure stability of measurement without affecting the inherent pro- perties of the tape. 4.2.4 Tape to head force The tape to head force shall be such that maximum short wave

34、length output stability is obtained. 4.2.5 Tape wrap Tape wrap is defined as the total angular displacement of the tape by the head. The tape wrap shall be in accordance with the recommendation of the relevant head manu- facturer and shall be adjusted for maximum short wavelength response. 4.3 4.3.1

35、 Electrical characteristics of test equipment Electrical characteristics of test equipment shall be in accordance with IEC 1120-1 4.3.2 Heads Heads authorized by the equipment manufacturers shall be used. 4.4 Reference tapes Unrecorded magnetic tapes with specified properties intended to be used as

36、a basis of comparison with other magnetic tapes or to measure the characteristics of tape recorders. 4.4.1 Reference tapes shall be provided on the basis of a primary standard issued from an agreed carefully measured batch of tape and shared among all member national standards organizations. Primary

37、 reference tapes shall be periodically revised to ensure they are compatible with currently available tape recorders of various categories covered by this part. 4.4.2 The measurements on these primary reference tapes shall be certified by the issuing national standards organization and verified by a

38、 second IEC member national standards organization able and prepared to do so. - Page 8 EN 61120-4 : 1992 Reference Country of batch Use origin number 8 O00 Mandatory USA TYP9 Format A and Format B 3404583 0082933 551 Tape speed (cm/s) 19,05 and Table 1 - Primary reference tape Tape width (mm) 63 De

39、scription CoFe, O, (oxide) NOTE - Format A and Format B are specified in IEC 1120-2 and IEC 1120-3 respectively. 4.4.3 Secondary reference tape Unrecorded magnetic tape intended to be used for routine measurement purposes, the properties of which are known and stated in relation to those of the prim

40、ary reference tape. NOTE - Gee annex A for the name and address of the manufacturer of primary standard IEC reference tapes. 4.5 The tape to be tested shall be erased. Condition of the tape to be tested The residual signal level shall be 50 dB below the average signal level at a test density of both

41、 A and B. 5 Electrical parameters to be measured 5.1 Resolution The resolution is the difference between the average signal level at test density B and that at test density A, when both are measured using the test recording current specified in 3.8. 5.1 .1 Relative resolution The relative resolution

42、 is expressed by D, where: where d is the resolution of the tape to be tested do is the resolution of the reference tape 3404583 0082934 498 Page 9 EN 61120-4 : 1992 5.2 Overwrite characteristic The overwrite characteristic is defined as the difference between the average signal level of a recording

43、 at test density A using the test recording current specified in 3.8 and the residual average signal level after overwriting the same portion of the tape at test density B using the same recording current. 5.2.1 Relative overwrite characteristic Relative overwrite characteristic is expressed by W, w

44、here: w= w- wo where w is the overwrite characteristic of the tape to be tested wo is the overwrite characteristic of the reference tape 5.3 Drop-outs (for definition, see IEV 806-0564). NOTE - Drop-outs can be caused by factors other than those listed. A method is not explicitly specified at presen

45、t. 5.4 A square wave of frequency Fb is recorded on the tape at the test recording current, and the noise level shall be measured with a bandwidth of from 200 Hz to 500 Hz at a nominal frequency of either 70 kHz at a tape speed of 19,05 cm/s, or of 140 kHz at a tape speed of 38,l cm/s (see figure 3)

46、. Relative average signal level to noise ratio The relative average signal level to noise ratio is expressed by M, where: M=m-mo where m is.the relative value in decibels of the average signal level at density B to the noise level for the tape to be tested mo is the relative value in decibels of the

47、 average signal level at density B to the noise level for the reference tape NOTE - Further improvement of the conditions of measurement is under consideration. 5.5 The relevant definitions and methods of measurement of IEC 94-5 shall apply. Characteristics of the sub-tracks in case of bias-recordin

48、g International Electrotechnical Vocabulary (IEV), IEC 50(806). Page 10 EN 61120-4 : 1992 3.6 Recommended recording current relative to the reference recording current 6 Recommended parameters to be described in published data for professional digital audio tapes % M M Table 2 - Recommended paramete

49、rs 5.1.1 Relative resolution 5.2.1 Relative overwrite characteristic 5.3 Droi outs 5.4 Relative average signal level to noise ratio Tape speed I I I dB M M dB M M n/min O O dB M M Electrical parameters for digital recording I Unit I I 38,l cmls I 19,05 cm/s 3.9 Average signai level at test density A relative to the standard reference levei I I I I I I M IdBIMI 3.9 Average signai level at test density B relative to the standard reference levei M : mandatory parameter O : optional parameter 7 Mechanical parameters to be measured The mechanical parameters to be measur