1、STD-BSI BS EN b0774-2-ENGL 2000 1b24bb9 0870182 6 BRITISH STANDARD Helical-scan video tape cassette system using 12,65 mm (0,5 in) magnetic tape on type VHS - Part 2: FM audio recording The European Standard EN 6077422000 has the status of a British Standard ICs 33.160.40 NO COPYING WTEOUT BSI PERMI
2、SSION EXCEPT As PERMITTED BY COPYBIGBT LAW rn 3s EN i0774-2:2000 EC iO774-2:1999 STD*BSI BS EN b0774-2-ENGL 2000 m lb24bb9 0870l183 583 BS EN 60774-2:2OOO National foreword This British StanM is the official English language version of EN 6077422000. It is identicai with IEC 6077421999. It supersede
3、s BS EN 610549993 which is Withdrawn. The UK participation in its preparation was entrusted by Technical Committee EPU100, Audio, video and multimedia systems, to Subcommittee EPUlW, Recording, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible inte
4、donaVEuropean committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; - monitor related intedonai and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obained on request to its sec
5、retary. From 1 January 1997, all IEC publications have the number 60000 added to the old number. For instance, IEC 27-1 has been renumbered as IEC 60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. Cros
6、s-references Attention is dram to the fact that CEN and CENELEC Standards nody include an annex which lists nonnative references to internationai publications with their corresponding European publications. The British Standards which implement these intemational or European publications may be foun
7、d in the BSI Standards Catalogue under the section entitled “Inkrnational Standards Correspondence Index“, or by using the “Find“ facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards
8、are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 11 and a back cover. The BSI copyright notice disp
9、layed in this document indicates when the document was last issued This British Standard, having been prepared under the direction of the Electsotechnical Sector Committee, was published under the authority of the Standards Committee and comes Amendments issued since publication 1 into effect on 15
10、September 2000 g BSI 09-2000 ISBN O 580 36437 2 1 comments STD-BSI BS EN b0774-2-ENGL 2000 Lb24bb9 0870184 41T = EUROPEAN STANDARD EN 60774-2 NORME EUROPENNE EUROPISCHE NORM February 2000 Supersedes EN 61 054: 1993 ICs 33.1 60.40 English version Helical-scan video tape cassette system using 12,65 mm
11、 (085 in) magnetic tape on type VHS Part 2: FM audio recording (IEC 60774-2: 1 999) Systme de magntoscope cassette balayage hlicodal utilisant la bande magntique de 12,65 mm (0,5 in) de format VHS VHS-Format Partie 2: Enregistrement audio MF Video-Band kassettensystem mit Schrgspuraufzeichnung auf M
12、agnetband 12,65 mm (0,5 in) Teil 2: FM-Tonaufzeichnung (CE1 60774-2:1999) (IEC 60774-2:1999) This European Standard was approved by CENELEC on 2000-01-01. CENELEC members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the
13、 status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, Ger
14、man). 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 the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech R
15、epublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee f
16、r Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2000 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 60774-232000 E _ STD*BSI BS EN b0774-2-ENGL 2000 = 1b24bb9 0870185 35b Page 2 EN 60774-2:2
17、000 Foreword The text of document 1 OOB/234/FDIS, future edition 1 of IEC 60774-2, prepared by SC 1 OOB, Audio, video and multimedia information storage systems, of IEC TC 100, Audio, video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENEL
18、EC as EN 60774-2 on 2000-01-01. This European Standard supersedes EN 6 1054: 1993. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical latest date by which the national standards conflicting national standard or by endors
19、ement (dop) 2000-1 0-01 with the EN have to be withdrawn (dow) 2003-0 1 -O 1 Annexes designated “normative“ are part of the body of the standard. In this standard, annexes A and ZA are normative. Annex ZA has been added by CENELEC. Endorsement notice The text of the International Standard IEC 60774-
20、2:1999 was approved by CENELEC as a European Standard without any modification. CONTENTS Page Clause 1 2 3 4 5 6 Scope 4 Normative references 4 Recording method . 4 Mechanical configuration . 4 FM audio track pattern 4 4.1 4.2 4.3 Head azimuth angles 5 Recording time difference . 5 Recording charact
21、eristics . 5 5.1 Noise reduction 5 5.2 Pre-emphasis . 5 5.3 Carrier centre frequency . 6 5.4 Frequency deviation . 6 5.5 Modulation polarity . 6 5.6 Recording level . 6 Other subjects (channel application) 6 Figure 1 . Track arrangement 7 Figure 2 . Pre-emphasis frequency response . 7 Figure 3 . Sig
22、nal spectrum 8 Figure 4 . Block diagram of FM audio recording . 8 Figure 5 . Block diagram of noise reduction system . 9 Figure A.l . Encoder transient measurement method . 10 Table 1 . FM audio track dimensions . 5 Table 2 . Head azimuth angles 5 Table 3 . Carrier centre frequencies 6 Table 4 . Cha
23、nnel applications 6 Annex A (normative) Encoder transient measurement method . 10 Annex ZA (normative) Normative references to international publications with their corresponding European publications 11 O BSI 09-2000 STD-BSI BS EN 60774-2-ENGL 2000 1b24669 0870187 129 Page 4 EN 60774-2:2000 HELICAL
24、-SCAN VIDEO TAPE CASSETTE SYSTEM USING 12,65 mm (0,5 in) MAGNETIC TAPE ON TYPE VHS - Part 2: FM audio recording 1 Scope This part of IEC 60774 is applicable to frequency modulation (FM) audio recording fully compatible with the VHS system defined in IEC 60774-1. The object of this standard is to def
25、ine the electrical and mechanical characteristics of FM audio recording which will provide for the interchangeability of recorded cassettes. The requirements given relate to 525 line-60 field and 625 line-50 field systems. 2 Normative references The following normative documents contain provisions w
26、hich, through reference in this text, constitute provisions of this part of IEC 60774. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of IEC 60774 are encouraged to investigate the possibility
27、 of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and IS0 maintain registers of currently valid International Standards. IEC 60774-1:1994, Helical-scan video tape
28、cassette system using 12,65 mm (0,5 in) magnetic tape on type VHS - Part 1: VHS and compact VHS video cassette system 3 Recording method The method of recording audio signals by frequency modulation is specified. The audio signal is recorded in the deep layer of the magnetic tape in the video track
29、area prior to the video recording, with additional audio heads mounted on the common video rotating drum. The video signal is recorded on the surface layer according to IEC 60774-1 (depth-multiplex recording system). The audio and video heads have different inclined azimuth gap angles in order to pr
30、event mutual influences between audio and video signals. 4 Mechanical configuration 4.1 FM audio track pattern The FM audio tracks are located in the centre of the video tracks as shown in figure 1. The dimensions shall be in accordance with table 1. Q BSI 09-2000 STDOBSI BS EN b0774-2-ENGL 2000 = L
31、b24hb9 OB7OLBB Ob5 Page 6 EN 60774-22000 Al, A2 Table 1 - FM audio track dimensions 525 line-60 field Min. 0,010 rnm Max. 0,029 rnm 625 line-50 field Min. 0,008 mm Max. 0,0245 mm 4.2 Head azimuth angles The head azimuth angles shall be in accordance with table 2. Table 2 - Head azimuth angles I I Ch
32、annel 1 I Channel 2 I I FM audio head azimuth angle I -30“ I30 I +30 I30 I I -6 a) I +e0 a) I I Video head azimuth angle I These values are from IEC 60774-1. I 4.3 Recording time difference The FM audio heads shall be arranged so that the FM audio signal is recorded within the time difference of two
33、 fields before the video signal is recorded on the same point of the track. 5 Recording characteristics Two channels of audio signal are recorded as FM signals with different carrier frequencies. The recording signal spectrum is shown in figure 3. The block diagram of this system is shown in figure
34、4. 5.1 Noise reduction The noise reduction encoder shall be composed as in figure 5 and shall be in accordance with the characteristics given below: - detection method: peak detection; - compression ratio: 2:l logarithmic compression; - attack time: 3 ms to 10 ms (see annex A); - recovery time: 70 m
35、s with a relative tolerance of k20 % (see annex A). 5.2 Pre-emphasis The pre-emphasis circuit shall have a frequency response as given in figure 2, with time constants as follows: - TI = (56 k 20 %) PS; - T2 = (20 i 20 %) ps. Q BSI 09-2000 Page 6 EN 60774-2:2000 525 line-60 field 1,3 MHz f 10 kHz CH
36、-L 5.3 Carrier centre frequency The carrier centre frequencies shall be shown in table 3, below. 625 line-50 field 1,4 MHz f 10 kHz 1,7 MHz f 10 kHz CH-R 1,8 MHz f 10 kHz I 5.4 Frequency deviation Frequency deviation shall be as follows: Monaural recording CH - L Monaural signal CH - R Monaural sign
37、al - maximum frequency deviation: 11 50 Hz; - operating frequency deviation: I50 kHz at 400 Hz (frequency deviation at the reference level). Main - sub-recording Main signal Subsignal 5.5 Modulation polarity The modulation polarity of CH-L and CH-R audio signals shall be the same. 5.6 Recording leve
38、l The FM audio signal shall be recorded so that the playback levels of the left and right channels will be approximately equal and at a maximum level after the video signal is recorded. 6 Other subjects (channel application) In the case of stereo recording, the channel application of the FM audio si
39、gnal shall be as shown in table 4. Q BSI 09-2000 STD-BSI BS EN b0774-2-ENGL 2000 = 1b24bbS 0870190 713 = Page 7 EN 60774-22000 Channel 1 audio track (L) I Channel 2 audio track (R) u1 c O n o al K I I I Centre line of video track IEC 1723/99 Figure 1 - Track arrangement 1 fl = - 2aTi 6 dBloct. 1 f2
40、= - 2nT2 Frequency IEC 1724/99 Figure 2 - Pre-emphasis frequency response g BSI 09-2000 Converted chrominance carrier CH-L Noise Pre- reduction emphasis (Main) Luminance-FM signal band amplifier FM modulation 2 3 CH-R Noise Pre- FM - 1 L o- emphasis reduction (Sub) 1 modulation 1 R I 4 f- l- 1 White
41、 peak frequency + Frequency (MHz) 2 3 4 trequency (MHZ) IEC 1725/99 Figure 3 - Signal spectrum FM audio heads Input audio signal IEC 1726199 Figure 4 - Block diagram of FM audio recording Q BSI 09-2000 STD=BSI BS EN b0774-2-ENGL 2000 Lb24bb9 0870192 596 W Page 9 EN 60774-2:2000 - Detecting Weighting
42、 Il V O TI = 240 p T2 = 24 ps T2=56p -6 dB/oct. u VCA Noise reduction IEC 1727/99 Figure 5 - Block diagram of noise reduction system 0: Q BSI 09-2000 c emphasis STDaBSI BS EN b0774-2-ENGL 2000 3b24hb9 0870393 422 m Page 10 EN 60774-2:2000 Annex A (normative) Encoder transient measurement method Enco
43、der transmission Encoder output IEC 7728/99 O dB: corresponding to 400 Hz maximum deviation Attack time Recovery time IEC 7729/99 Figure A.l - Encoder transient measurement method 8 BSI 09-2000 STD-BSI BS EN 60774-2-ENGL 2000 Lb24669 087029Li 369 m Page 11 EN 60774-2:2000 Annex ZA (normative) Normat
44、ive references to international publications with their corresponding European publications This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are liste
45、d hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). NOTE r
46、elevant ENIHD applies. When an international publication has been modified by common modifications, indicated by (mod), the Publication - Year Title Year EN/HD - IEC 60774-1 1994 Helical-scan video tape cassette system EN 60774-1 1994 using 12,65 mm (0,5 in) magnetic tape on type VHS Part 1: VHS and
47、 compact VHS video cassette system BS EN 60774-2:2000 IEC 60774-2:1999 BSI 389 Chiswick High Road London w4 4AL BSI - British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the internationa
48、l level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or raision. Users of British Stan* shouid make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be g
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