1、CENELEC EN*b3237-L 94 m 3404583 0346777 725 m BRITISH STANDARD Broadcast video tape recorders - Methods of measurement Part 1. Mechanical measurements The European Standard EN 61237-1 : 1994 has the status of a British Standard UDC 621.397.452 : 621.317.08 BS EN 51237-1 : 1995 EC 1237-1 : 1994 CENEL
2、EC EN*bL237-3 94 W 3404583 0346778 bb3 = Amd. No. Date BS EN 61237-1 : 1995 Text affected This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 January 1995 O BSI 1995
3、 “he following BSI references relate to the work on this standard: Committee reference EEIJ22 Draft for comment 91/03062 DC ISBN O 680 23644 O Co operating organizations The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared
4、, comprises the national committees of the following countries: Austria Belgium Denmark Finland France Germany Greece Iceland Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom BS EN 61237-1 : 1995 Contents Page Cooperating orgaiuzations Inside front cover K
5、ational foreword i Foreword 2 Text of EN 61237-1 3 Kational annex KA (informative) Committees responsible Inside back cover Kational annex KB (informative) Cross-references Inside back cover National foreword This British Standard has been prepared under the direction of the Electrotechnical Sector
6、Board ancl is the English language veision of EN 62379-1 : 1994 Broudccist video tupe recorders - Methocls of ?necisure?nevzt. Purt 1 : Mecha nicu 1 wzectsiwernen ts, published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC 1237-1 : 1994, published
7、 by the International Electrotechnical Commission (IEC). BS EX 61237 consists of the following Pai-ts: Pai-t 1 Meclanical mecistmments Part 2 Electrical ?neisurernerzts fw amilogzce composite video signals Part 3 ElectRcul ?nectsurtments for auiloy.zce cwmporwzt video siynulls Part 4 Mecisuremerzt o
8、f ct.rcdio peoi-rna?zce-u?iuloe Compliance with a British Standard does not of itself confer immunity from legal obligations. i CENELEC ENrb1237-1 94 3404583 014b780 21T W EUROPEAN STANDARD EUROPISCHE NORM NORME EUROPENNE EN 61237-1 July 1994 UDC 621.397.452 : 621.317.08 Descriptors: Electroacoustic
9、s, video recording, recording apparatus, video tape recorders, radiocommunications, mechanical measurements, compatibility English version Broadcast video tape recorders Methods of measurement Part 1 : Mechanical measurements (IEC 1237-1 1994) Magntoscopes de radiodiffusion Mthodes de mesure Partie
10、1 : Mesures mcaniques (CE1 1237-1 : 1994) MeBverfahren fr Videobandgerte fr den Rundfunk Teil 1 : Mechanische Messungen (IEC 1237-1 : 1994) This European Standard was approved by CENELEC on 1994-03-08. CENELEC members are bound to comply with the CENKENELEC Internal Regulations which stipulate the c
11、onditions for giving this European Standard the 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 i
12、n 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 the same status as the official versions. CENELEC members are the national electrote
13、chnical committees of Austria, Belgium, 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 Electro
14、technique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels O 1994 Copyright reserved to CENELEC members Ref. No. EN 61237-1 : 1994 E CENELEC EN*b3237-3 94 3404583 0346783 356 Page 2 EN 61237-1 : 1994 Foreword The text of document 60B(C0)158, a
15、s prepared by Sub-committee 60B: Video recording, of IEC %chnical Committee 60: Recording, was submitted to the IEC-CENELEC parallel vote in April 1993. The reference document was approved by CENELEC as EN 61237-1 on 8 March 1994. The following dates were fixed: - latest date of publication of an id
16、entical national standard (dop) 1995-06-01 - latest date of withdrawai of conflicting national standards (dow) 1995-06-01 Annexes designated normative are part of the body of the standard. Annexes designated informative are given only for information. In this standard, annexes A and ZA are normative
17、 and annex B is informative. . - . CENELEC EN*bL237-1 94 W 3q04583 0146782 O92 W Page 3 EN 61237-1 : 1994 CONTENTS Chuse 1 Scope . 2 Normative references . 3 General 4 Test conditions 5 Measuring equipment 5.1 Mechanical measurements . 5.2 Optical measurements . 6 Recorder measurements . 6.1 Diamete
18、r of drum 6.2 Projection of video head pole tips 6.2.1 Mechanical measurement . 6.2.2 Optical measurement 6.3 Gap width of video heads . 6.4 Coplanarity error of video heads Measurements on recorded tape 7.1 Tape speed and pitch of the video tracks . 7.1.1 Tape speed v (first method) . 7.1.2 Track p
19、itch J (first method) . 7.1.3 7 Tape speed and pitch of the video tracks (second method) . 7.2 Position of the video reference point (VRP) : 7.2.1 Measurement of the VRP position (first method) . 7.2.2 Tracking and drum phase error (second method) . Location of records on sound and time code tracks
20、7.3.1 Track location to the reference tape edge 7.3 4 4 5 5 5 5 5 5 5 6 6 6 6 6 7 8 8 8 8 8 9 9 9 9 7.3.2 Video track geometry . 10 7.4.1 Video track width I . 10 7.4.2 7.4.3 Longitudinal location of records . 10 7.4 Cross-tape measuring technique (first method) . 10 Dynamic track measurement (secon
21、d method) 11 13 Figures Annexes A Magnetic development of recorded tape . 15 B Bibliography 16 ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications . 17 CENELEC EN*b1237-1 94 W 340458i- 0146783 T2q i Page 4 EN 61237-1 : 199
22、4 BROADCAST VIDEO TAPE RECORDERS - METHODS OF MEASUREMENT - Part I : Mechanical measurements i Scope This part of IEC 1237 describes the mechanical measurement methods on video tape recorders relating to the compatibility parameters for recording and measuring methods of the recorded tape. The allow
23、able 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 .e. appropriate publications, manufacturers? specifications, etc. The necessary reference and calibration tapes are either mentioned in th
24、e specific IEC publication of the equipment under test or included in IEC 1105. This standard deals with special mechanical measurement techniques for broadcast VTRs. It does not, however, cover the special mechanical measurements of the earlier transverse track video recorder standard (IEC 347). Fo
25、r those measurements see IEC 1055. The methods are applicable to acceptance tests, Performance comparison and, as far as possible, for routine checks. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part
26、 of IEC 1237. 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 IEC 1237 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicat
27、ed below. Members of IEC and IS0 maintain registers of currently valid International Standards. IEC 347: 1982, Transverse track video recorders IEC 461 : 1986, Time and control code for video tape recorders IEC 1055-1 : 1991, Measurement techniques and operational adjustments of broadcast VTs - Part
28、 i: Operational adjustments on analogue composite broadcast VTRs (Report) IEC 1055-2: 1991 , Measurement techniques and operational adjustments of broadcast VTRs - Part 2: Special mechanical measurements and alignments (Report) IEC 1 105: 1991, Refereme tapes for video tape recorder systems -il- - -
29、 - CENELEC -EZZ37-1 94 3404583 0346784 96C-E- Page 5 EN 61237-1 : 1994 3 General To ensure 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 signals, measuring devices and types of tapes used together with t
30、he results obtained. 4 Test conditions If not otherwise statec, all measurements s condit ions : all be carried out a the following atmospheric - temperature 20 OC f 1 OC; - relative humidity 50 Yo f 2 Yo; - air pressure 86 kPa to 106 kPa; - conditioning before testing 24 h. 5 Measuring equipment 5.
31、1 Mechanical measurements For some measurements, precision micrometers or dial indicators with 1 pm resolution are sufficient. Instruments with electrical read-out should be preferred. For drum geometry measurements a three-coordinate measuring device with an accuracy below 1 pm is recommended. 5.2
32、Optical measurements Measurements are made by a high power microscope equipped with an X-Y-table and a scaled Z-axis. For measurements in the pm area the microscope objective shall have a magnification of 50x and a numerical aperture of 0,85. The eye-piece, equipped with cross-hairs shall have a mag
33、nification 21 Ox. A video camera/monitor system with electronic cross-hairs gives better reproducible results. The X-Y-table shall have a measuring range of at least 100 mm x 50 mm. The measuring accuracy in X-, Y- and Z-axis shall be I 1 pm. For data acquisition and processing a computer is recomme
34、nded. 6 Recorder measurements 6.1 Diameter of drum The drum is measured by means of a precision micrometer or a multicoordinate measuring system. Measurements are made at several points of the drum, and these points shall be specified by the appropriate standard or the manufacturer. - - - - - - CENE
35、LEC EN*b1237-1 74 3404583 0146785 8TL Page 6 EN 61237-1 : 1994 6.2 Projection of video head pole tips 6.2.1 Mechanical measurements Measurements are made by means of a precision dial indicator. Usually either the upper or the lower drum serves as reference, depending on the specifications of the sta
36、ndard or of the VTR manufacturer. The measuring device is specified and often supplied by the VTR manufacturer. Instructions and precautions are given in the users manual of the measuring device. 6.2.2 Optical measurements The scanner is mounted on the microscope table with the rotating axis paralle
37、l to one table axis. Adjust the second table axis so that the optical axis crosses the rotating axis and lock. Focus to the drum surface at the reference area as specified and set the Z-axis measure to zero. Shift the table and rotate the drum till the video head gap under test is at *the image cent
38、er. Focus to the head gap and read the tip projection in the Z-axis. 6.3 (The dimension of magnetic gap parallel to the plane of the tape and perpendicular to the direction of the relative tape to head movement) Gap width of video heads Scanner mounting is the same as in 6.2.2. Focus on the head gap
39、 under test and measure the head gap width. For azimuth heads measure the projected width of the gap. 6.4 Scanner mounting is the same as in 6.2.2, rotate from head to head. Coplanarity error of video heads The center of the head gap width is the standard measuring point for all p-iy heac; and guard
40、 band recording heads. In systems with overlap recording (gap widthis more than the track pitch), the gap edge of the record or erase head which overlaps the prior recorded track is to be measured. In systems with separate video heads for record, play and erase the video heads are located in differe
41、nt planes. If the video heads of one type (e.g. record) are not in a constant angular distance it yields in an axial displacement, This displacement shall be considered so that all video heads of one type are measured in one plane (e.g. record plane). - CENELEC EN*b3237-3-94 -A 3404583 0346786 738-i
42、 Page 7 EN 61237-1 : 1994 The coplanarity error is the peak-to-peak deviation in one plane. The result is measured in micrometers, center measure or corner measure shall be stated. 7 Measurements on recorded tape A first method is to record a tape and make the magnetic footprint on tape visible by d
43、eveloping it by means of a suspension of ferro-magnetic powder. Methods for this developing are described in annex A. Measurement is then made by the microscope. This method is precise and gives absolute values. A second method is to playback a calibration tape. This method is practice-orientated an
44、d gives a quick overview. Dynamic effects become visible. The results are less accurate because the errors of the calibration tape are always implemented and influenced by ageing. Good results are obtained by comparing recordings of the same calibration tape at the same time. Nomenclature T: t: e: L
45、: v: ht : n: m: I: J: s: P: x: c: r: PI e: ct : v: basic time interval between control pulses; measured time intervals; basic track angle; distance for n control track pulses; tape speed; relative head to tape speed: number of control track pulses in distance L; number of tracks recorded during time
46、 interval T; track width: track pitch; longitudinal track pitch; control track head position: drum phase position; index for playing the calibration tape; index for running in recording mode; index for playing own recording; index for error value; index for control track pulse; index for vertical pu
47、lse. Page 8 EN 61237-1 : 1994 7.1 Tape speed and pitch of the video tracks On video tape recording are tape speed v, track pitch J and control pulse distances in a fixed relationship, defined by the recording standard. With one measurement the others can be calculated. For measurement, the control t
48、rack is to be used. 7.1 .I The tape speed results from the control track pulse distance divided by the basic time interval T. Tape speed v (first method) For high accuracy it is advisable to use a number of pulses n with a low repetition rate (edit pulse, colour frame pulse) for measurement so the m
49、easuring L distance will be in the range of about 100 mm. Tape speed v = U(n x T) mm/s 7.1.2 Track pitch J (first method) The track pitch is the average distance of the track centers measured perpendicular to the recorded tracks. Track pitch J = L x sin(e)/(n x m) pm Longitudinal track pitch S = L /(n x m) pm 7.1.3 Measurement is made by comparing the tape speed vr in normal record mode (not an insert mode) and the tape speed vc by playing back the calibration tape. Tape speed and pitch of the video tracks (second method) Measure t
