1、BRITISH STANDARD BS EN 61237-4:1998 IEC 61237-4: 1997 Broadcast video tape recorders Methods of measurement Part 4: Analogue audio performance measurements The European Standard EN61237-4:1997 has the status of a British Standard ICS 33.160.40BSEN 61237-4:1998 This British Standard, having been prep
2、ared under the directionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15 February 1998 BSI 04-1999 ISBN 0 580 28891 9 Amendments issued since publication Amd. No. Date CommentsBSEN61237-4:1998 BSI 04-1999 i Contents Page Nationa
3、l foreword ii Foreword 2 Text of EN 61237-4 3BSEN 61237-4:1998 ii BSI 04-1999 National foreword This British Standard is the English language version of EN61237-4:1997. It is identical with IEC61237-4:1997. The UK participation in its preparation was entrusted by Technical Committee EPL/100, Audio,
4、video and multimedia systems and equipment, to Subcommittee EPL/100/3, Equipment in the field of audio, video and audiovisual engineering, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpret
5、ation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. From 1 January 1997, all IEC publications h
6、ave the number60000 added to the old number. For instance, IEC27-1 has been renumbered as IEC60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. IEC 61237 comprises the following Parts: Part 1: Mechanica
7、l measurements; Part 2: Electrical measurements of analogue composite video signals; Part 3: Electrical measurements of analogue component signals; Part 4: Analogue audio performance measurement; Part 5: Electrical measurements of digital composite video signals and digital audio signals; Part 6: El
8、ectrical measurements of digital component video signals and digital audio signals. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative references to international publications with their corresponding European publications.
9、The British Standards which implement these international or European publications may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does
10、 not purport to include all the necessary provisions of a contract. Users of British Standards 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 insid
11、e front cover, pages i and ii, theENtitle page, pages 2 to 16 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 6
12、1237-4 November 1997 ICS 33.160.40 Descriptors: Electroacoustics, video recording, recording apparatus, magnetoscopes, radiocommunications, measurements, characteristics, acoustic signals, analog signals English version Broadcast video tape recorders Methods of measurement Part 4: Analogue audio per
13、formance measurements (IEC 61237-4:1997) Magntoscopes de radiodiffusion Mthodes de mesure Partie 4: Mesure des caractristiques audio-analogiques (CEI 61237-4:1997) Videobandgerte fr den Rundfunk Meverfahren Teil 4: Messung der Leistungskennwerte fr analoge Tonsignale (IEC 61237-4:1997) This European
14、 Standard was approved by CENELEC on 1997-10-01. CENELEC members 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 without any alteration. Up-to-date lists and bibliographical references co
15、ncerning 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, German). A version in any other language made by translation under the responsibility of a CENELEC member in
16、to 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 Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Nor
17、way, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1997 CENELEC All rig
18、hts of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61237-4:1997 EEN61237-4:1997 BSI 04-1999 2 Foreword The text of document 100B/93/FDIS, future edition 1 of IEC61237-4, prepared by SC100B, Recording, of IEC TC100, Audio, video and multimedia systems
19、 and equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN61237-4 on 1997-10-01. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. Annexes designated “informative” are given for information only. In this standar
20、d, Annex ZA is normative and Annex A andAnnex B are informative. Annex ZA has been added by CENELEC. Endorsement notice The text of the International Standard IEC 61237-4:1997 was approved by CENELEC as a European Standard without any modification. In the official version, for Annex B, Bibliography,
21、 the following note has to be added for the standard indicated: IEC 60094-2 NOTEHarmonized as EN60094-2:1995 (notmodified). Contents Page Foreword 2 1 General 3 1.1 Scope and object 3 1.2 Normative references 3 1.3 Definitions 3 2 Manual and automatic measurements 4 3 Procedure of measurement 4 4 En
22、vironmental conditions 4 5 Measurements on analogue audio baseband recording using bias 4 5.1 Reproducing performance using calibration tape 4 5.2 Overall performance using reference tape 5 6 Measurement on analogue audio recording using frequency modulation (FM audio) 8 6.1 Reproducing performance
23、using calibration tape 8 6.2 Overall performance using reference tape 9 7 Special measurements 10 7.1 Measurements on FM carrier (unmodulated carrier and deviation) 10 7.2 Measurements on AGC (amplitude characteristic; attack time; hold time) 11 7.3 Measurements on switchable noise reduction circuit
24、s 11 7.4 Measurements on non-switchable noise reduction systems (in combination with a non-switchable AGC) 12 7.5 Polarity test 13 Annex A (informative) Method of measurement for magnetic tape flux 14 Annex B (informative) Bibliography 15 Annex ZA (normative) Normative references to international pu
25、blications with their corresponding European publications 16 Figure 1 Bias characteristics 6 Figure A.1 Tape transport 14 latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 1998-07-01 latest date by which the n
26、ational standards conflicting with the EN have to be withdrawn (dow) 1998-07-01EN61237-4:1997 BSI 04-1999 3 1 General 1.1 Scope and object This part of IEC61237 describes methods of measurement and special test signals for the analogue audio part of equipment mainly dedicated to recording reproducti
27、on of TV signals on magnetic tape on reels or in cassettes. The allowable tolerances for the rated values for acceptable performance are not given in this standard, but may be derived from the specifications for the related system i.e.appropriate publications, manufacturers specifications, etc. The
28、necessary reference and calibration tapes are either mentioned in the specific IEC publication of the equipment under test or included in IEC61105 and IEC61295, respectively. The methods are applicable to acceptance tests, performance comparison and, as far as possible, to routine checks. To ensure
29、that the results obtained at a specific time and at a specific place are comparable to other measurements, it is advisable to specify the test signal, measuring devices and types of tapes used together with results obtained. 1.2 Normative references The following normative documents contain provisio
30、ns which, through reference in this text, constitute provisions of this part of IEC61237. At the time of publication, the editions indicated were valid. All normative documents are subject to revision and parties to agreements based on this part of IEC61237 are encouraged to investigate the possibil
31、ity of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 60094-3:1979, Magnetic tape sound recording and reproducing systems Part 3: Methods of measuring the characteristics of recor
32、ding and reproducing equipment for sound on magnetic tape. IEC 60268-1:1985, Sound system equipment Part1: General. IEC 60268-2:1987, Sound system equipment Part2: Explanation of general terms and calculation methods. IEC 60268-3:1988, Sound system equipment Part3: Amplifiers. IEC 60268-8:1973, Soun
33、d system equipment Part8: Automatic gain control devices. IEC 60386:1972, Method of measurement of speed fluctuations in sound recording and reproducing equipment. IEC 60602:1980, Type B helical video recorders. IEC 60651:1979, Sound level meters. IEC 61041-1:1990, Non-broadcast video tape recorders
34、 Methods of measurement Part1:General video (NTSC/PAL) and audio (longitudinal) characteristics. IEC 61041-3:1993, Non-broadcast video tape recorders Methods of measurement Part3:Audio characteristics for FM recording. IEC 61105:1991, Reference tapes for video tape recorder systems. IEC 61213:1993,
35、Analogue audio recording on video tape Polarity of magnetization. IEC 61260:1995, Electroacoustics Octave-band and fractional-octave-band filters. IEC 61295:1994, Calibration tapes for broadcast VTRs. ITU-R Recommendation BS 468-4:1990, Measurement of audio-frequency noise voltage level in sound bro
36、adcasting. ITU-R 798-2:1990, Simulated programme signals. 1.3 Definitions For the purpose of this part of IEC 61237, the following definitions apply: 1.3.1 reference level value of signal level defined in the relevant system IEC publication as remanent magnetic short-circuit flux level on the tape,
37、for example 905nWb/m r.m.s. for 625-50 systems in IEC60602. Method of measurement is given in Annex A of this standard 1.3.2 crosstalk attenuation or track separation in multi-channel equipment, signals in one channel can break through into another channel in an attenuated and distorted form. Partic
38、ularly when two adjacent tracks are used or two adjacent channels in the same head stack are operated simultaneously in different modes for example record and reproduction, impairments can arise. To make matters worse, beside these audio tracks additional longitudinal tracks are present on a video t
39、ape for example control track and time and control code track the influence of a signal in one channel to another channel can be described in terms of crosstalk attenuation or track separationEN61237-4:1997 4 BSI 04-1999 1.3.3 polarity of the audio signal an audio signal is deemed to be positive whe
40、n it results in an increase in the acoustic pressure on the microphone diaphragm, and thus in the displacement of the diaphragm towards the rear (see IEC60268-2) 1.3.4 conservation of polarity on magnetic tapes to obtain an optimal audio reproduction it is necessary to make sure that a backward move
41、ment of the microphone diaphragm leads to a forward direction of the loudspeaker diaphragm. This should be preserved either during recording or tape interchange, detailed explanation is given in IEC61213 2 Manual and automatic measurements If an automatic measuring device is designed to give reliabl
42、e results under the special conditions of television tape recording/reproducing as for example drop-out, jitter, time-base errors, head switching or partly insufficient head-to-tape contact, a significant improvement in measuring speed, accuracy and comparability of results can be achieved. Therefor
43、e preference was given to measuring methods which can be carried out by automatic measuring equipment or which are suitable for automatic measuring techniques. Except where a distinction is made in particular clauses between manual and automatic methods of measurement, the measuring procedures given
44、 in this standard are valid for both methods. However, although in the case of automatic measurements the procedure is carried out automatically by the test signal analyzer, the various steps are described as if they were performed manually. 3 Procedure of measurement The measurements shall be carri
45、ed out by measuring the reproduced signal after recording on the same machine (best case configuration). In certain particular cases, if the multigeneration-performance of a TV signal recording system is measured, the measurements shall be carried out by measuring the reproduced signal after recordi
46、ng on a different machine (worstcase configuration). If the television tape machine under test is equipped with external controls for example tracking control, gain control, etc. these controls shall be set to their preset and mid-position respectively for all measurements. Before testing the overal
47、l performance, the reproducing channel shall be measured by means of a calibration tape (see1.1). Attention shall be paid to the manufacturers manual and instructions respectively. 4 Environmental conditions If not otherwise stated, all measurements shall be carried out at the following atmospheric
48、conditions: 5 Measurement on analogue audio baseband recording using bias 5.1 Reproducing performance using calibration tape An audio calibration tape according to IEC61295 or recommended by the manufacturer of the equipment under test shall be used for measuring the performance of the reproducing c
49、hain of each channel. If adjustable reproduction gain controls are provided on the equipment, they shall be adjusted to give the reference output level when reproducing the reference recording level. If adjustable reproduction-equalization controls are provided, they shall be adjusted to give the closest approximation to the specified reproducing characteristic when reproducing the frequency response section of the specified calibration tape. 5.1.1 Head adjustment The 10 kHz tone recorded on the calibration tap
