SIST EN 61327:1999

SLOVENSKI STANDARD
SIST EN 61327:1999
01-april-1999
Helical-scan digital composite video cassette recording system using 12,65 mm
(0,5 in) magnetic tape - Format D-3 (IEC 61327:1995)
Helical-scan digital composite video cassette recording system using 12,65 mm (0,5 in)
magnetic tape - Format D-3
Videokassettensystem mit Schrägspuraufzeichnung digitaler Composite-Signale auf
Magnetband 12,65 mm (0,5 in) - D3-Format
Système de magnétoscope numérique à chrominance composite à cassette à balayage
hélicoïdal utilisant la bande magnétique de 12,65 mm (0,5 in) - Format D-3
Ta slovenski standard je istoveten z: EN 61327:1995
ICS:
33.160.40 Video sistemi Video systems
SIST EN 61327:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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NORME
CEI
INTERNATIONALE
IEC
1327
INTERNATIONAL
Première édition
STANDARD
First edition
1995-07
Système de magnétoscope numérique
à chrominance composite à cassette
à balayage hélicoïdal utilisant la bande
magnétique de 12,65 mm (0,5 in) –
Format D-3
Helical-scan digital composite video
cassette recording system using
12,65 mm (0,5 in) magnetic tape –
Format D-3
© CEI 1995 Droits de reproduction réservés — Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun pro- any form or by any means, electronic or mechanical,
cédé, électronique ou mécanique, y compris la photocopie et including photocopying and microfilm, without permission
les microfilms, sans raccord écrit de l'éditeur. in writing from the publisher.
Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé Genève, Suisse
Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission PRICE CODE
IEC Mew iyHapopHaa 3nelcrporexHHuecrsaa HoMHccHt
vigueur • Pour prix, voir catalogue en
•
For price, see current catalogue

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1327 ©IEC:1995 — 3 —
CONTENTS
Page

11
FOREWORD

13
INTRODUCTION
Clause
15
1 General
15
1.1 Scope and object
15
1.2 Normative references
17
1.3 Definitions, symbols and abbreviations
17
2 Technical data
17
2.1 Environment and test conditions
19
2.2 Reference tape
2.3 Calibration tape 19
19
Record locations and dimensions
2.3.1
2.3.2 Calibration signals 19
2.3.3 Purchase 19
21
3 Video tape cassette
21
3.1 Mechanical parameters
21 3.1.1 Cassette dimensions
21 3.1.2 Identification of cassettes
21 3.1.3 Tape length, thickness and play times
23
3.1.4 Coating face
23
3.1.5 Datum planes
23
3.1.6 Window and labels
23
3.1.7 Identification holes
25
Leader/trailer tape 3.1.8
27
Reels 3.1.9
3.1.10 Lid 29
3.2 Video tape specification 29
3.2.1 Base 29
3.2.2 Width 29
31
Width fluctuation 3.2.3
31 3.2.4 Reference edge straightness
31
3.2.5 Tape thickness
31 3.2.6 Transmissivity
31
Offset yield strength 3.2.7
31
Magnetic coating 3.2.8
31
Coating coercivity 3.2.9
31 3.2.10 Particle orientation
33
4 Helical recordings
33
4.1 Tape speed

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- 5 -
13270O IEC:1995
Page
Clause
33 4.2 Erase head and record location and dimensions
33
4.2.1 Erase head
33 4.2.2 Record location and dimensions
33
4.2.3 Reference edge
33 4.2.4 Track pitch
33
4.2.5 Flying erase heads
33
4.3 Helical track record tolerance zones
35
4.4 Relative positions of recorded signals
35
4.4.1 Relative positions of the longitudinal tracks
35
4.4.2 Helical/control track relationship
35
4.4.3 Programme area reference point
35
4.5 Gap azimuth
35 Cue track, control track, time and control code track
4.5.1
35 4.5.2 Helical track
4.6 Transport and scanner 37
37
5 Programme track data arrangement
37
5.1 Introduction
37
5.2 Labelling convention
5.3 Sector details 39
5.3.1 Sync block 39
5.3.2 Sync pattern 39
39
Identification pattern 5.3.3
41
5.3.4 Data field
45
5.3.5 Sector preamble
47 5.3.6 Sector postamble
47
5.4 Edit gaps
47 5.5 Channel coding
47
5.5.1 Coding rules
49 5.5.2 Data rate and wavelength
51
5.6 Magnetization
51
5.6.1 Polarity
5.6.2 Recorded equalization 51
51
5.6.3 Record level
51
Video interface 6
51 Encoding parameters 6.1
51 Parallel digital signal interface 6.2
51
7 Audio interface
51
7.1 Encoding parameters
51
7.1.1 Sampling
53 7.1.2 Reference level
53
7.2 Digital signal interface

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– 7 –
1327 ©IEC:1995
Page
Clause
53
Video processing 8
53
8.1 Recorded and non-recorded data
Recorded samples of digital active line and lines
8.1.1
53
of the television frame
55
8.1.2 Non-recorded data
55
8.1.3 Source pre-coding
55
Channel distribution of samples
8.2
55
Shuffling 8.3
55
8.3.1 Introduction
57
8.3.2 Algebraic definition
Field data array 59
8.4
61
Outer error protection
8.5
61 Order of transmission to inner coding
8.6
63
9 Audio processing
63
9.1 Introduction
63
9.2 Source coding
65
9.3 Source processing
65
Introduction 9.3.1
65 Relative audio-video timing
9.3.2
65
Audio data in fields 9.3.3
65
9.3.4 Intra-field shuffling
67
Block shuffling 9.3.5
69
Audio data word processing
9.3.6
71
Auxiliary words 9.4
71
9.4.1 Channel use (CHAN)
73
9.4.2 Pre-emphasis (PREF)
75
9.4.3 Audio data word mode (LNGH)
75 9.4.4 Block sync location (S MARK)
77 Field number count (FNCT) for 525/60 system
9.4.5
77
9.4.6 Edit flag (EFLG)
Outer error protection 79
9.5
79
9.6 Inner protection
79
Order of transmission to inner coding
9.7
9.8 Channel code 79
81
Allocation of audio sectors 9.9
81
10 Longitudinal tracks
81
Relative timing 10.1
81
Time and control code input 10.1.1
81 Time and control code information
10.1.2
81
Cue information 10.1.3
81 Control track servo pulse
10.1.4

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– 9 –
1327 ©IEC:1995
Page
Clause
83
10.2 Control track
83 10.2.1 Method of recording
83 10.2.2 Servo reference pulse
83 10.2.3 Flux polarity
83
10.2.4 Flux level
83 10.2.5 Pulse width
83 Servo reference pulse timing
10.2.6
a3.
Colour frame pulse 10.2.7
83
Video frame pulse 10.2.8
85
10.3 Cue record
85 10.3.1 Method of recording
85
10.3.2 Flux level
85
Time and control code record 10.4
85
Method of recording 10.4.1
85
Flux level 10.4.2
85
10.4.3 Input signal
87
Figures
Annexes
257 A Cross-tape track measurement technique
267
B Track pattern during insert editing
269
Bibliography C

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-11 -
1327 ©IEC:1995
INTERNATIONAL ELECTROTECHNICAL COMMISSION
HELICAL-SCAN DIGITAL COMPOSITE VIDEO CASSETTE
RECORDING SYSTEM USING 12,65 mm (0,5 in)
MAGNETIC TAPE – FORMAT D-3
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and
electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.
Their preparation is entrusted to technical committees; any IEC National Committee interested in
the subject dealt with may participate in this preparatory work. International, governmental and
non-governmental organizations liaising with the IEC also participate in this preparation. The IEC
collaborates closely with the International Organization for Standardization (ISO) in accordance with
conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
3) They have the form of recommendations for international use published in the form of standards, technical
reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
International Standard IEC 1327 has been prepared by sub-committee 60B: Video
recording, of IEC technical committee 60: Recording.
The text of this standard is based on the following documents:
Report on voting
DIS
60B/272/RVD
60B/255/DIS
rt
Full information on the voting for the approval of this standard can be found in the repo
on voting indicated in the above table.
Annexes A and B form an integral part of this standard.
Annex C is for information only.

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1327©IEC:1995 – 13 –
INTRODUCTION
One video channel and four independent audio channels are recorded in digital form. Each
of these channels is designed to be capable of independent editing. The video channel
records and reproduces a composite television signal in the 525-line system with a frame
frequency of 29,97 Hz and 625-line system with a frame frequency of 25,00 Hz.
The video signal may be input and output in either analogue or digital form. The audio
signals may also be input and output in either analogue or digital form. In addition, a cue
audio signal is recorded in analogue form.
Figures 1 and 2 provide block diagrams of the processes involved in the recorder.

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1327 ©
IEC:1995 - 15 -
HELICAL-SCAN DIGITAL COMPOSITE VIDEO CASSETTE
RECORDING SYSTEM USING 12,65 mm (0,5 in)
MAGNETIC TAPE – FORMAT D-3
1 General
1.1
Scope and object
This International Standard defines the electrical and mechanical characteristics of equip-
ment which permits the interchangeability of 12,65 mm cassettes containing digitally
recorded composite video programmes.
This standard specifies the content, format and recording method of the data blocks
forming the helical records on the tape containing video, audio and associated data using
the 12,65 mm (0,5 in) type D-3 cassettes. In addition, this standard specifies the content,
format and recording method of the longitudinal record containing tracking information for
the scanning head associated with the helical records, as well as the longitudinal
cue audio and time and control code tracks. The requirements given relate to 525-line
composite television signals with a frame frequency of 29,97 Hz nominal (hereinafter
referred to as "525/60 system") and to 625-line composite television signals with a frame
frequency of 25,00 Hz (hereinafter referred to as "625/50 system").
1.2 Normative references
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this International Standard. At the time of publication, the
rties
editions indicated were valid. All normative documents are subject to revision, and pa
to agreements based on this International Standard are encouraged to investigate the
possibility 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 461: 1986, Time and control code for video tape recorders
IEC 735: 1991, Measuring method for video tape properties
IEC 958: 1989, Digital audio interface
IEC 1179: 1993, Helical-scan digital composite video cassette recording system using
19 mm magnetic tape, format D-2 (NTSC, PAL, PAL-M )
ITU-R Repo rt 624-4: 1990, Characteristics of television systems
ITU-R Recommendation 647-1: 1990, A digital audio interface for broadcasting studios

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1327 © IEC:1995 -17 -
Pre-emphasis used on sound-programme circuits
UIT-T Recommendation J.17: 1972,
(Fascicle 111.4)
1.3 Definitions, symbols and abbreviations
For the purpose of this International Standard, the following definitions apply.
1.3.1 ECL: Emitter coupled logic, a family of digital logic integrated circuits. In this
standard, ECL refers to the 10 000 series of logic integrated circuits.
1.3.2 GF Galois field: Mathematical field containing a finite number of elements in which
algebraic operations may be performed. The number of field elements is generally written
as an argument in parentheses, e.g. GF(256).
1.3.3 LSB
1) Least significant bit of a word of data.
2) Least significant byte of a data item consisting of two or more bytes.
1.3.4 MSB
1) Most significant bit of data.
Most significant byte of data item consisting of two or more bytes.
2)
1.3.5 ScH: Colour subcarrier to horizontal sync timing relationship.
1.3.6 ECC: Error correcting code.
2 Technical data
2.1 Environment and test conditions
Tests and measurements made on the system to check the requirements of this standard
shall be carried out under the following conditions.
20 ° C ± 1 ° C;
- temperature:
- relative humidity: (50 ± 2) %;
(96 ± 10) kPa;
- barometric pressure:
- tape tension: (0,31 ± 0,05) N; *
not less than 24 h.
- tape conditioning:
The value measured with a tension monitor on the entrance side of the scanner may vary between
manufacturers, but would typically be 0,30 N ± 0,03 N.

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1327 ©IEC:1995 - 19 -
2.2 Reference tape
Blank tape to be used for calibration recordings may be purchased from the following
manufacturers:
Company
Matsushita Electric Industrial Co., Ltd.
Audio and Video Systems Division
2-15, Matsuba-cho, Kadoma-city,
Osaka 571 Japan.
TEL.: +8 -6-90 -1161
FAX.: +8 -6-90 -4048
TLX.: +8 -6-52 -4690
Part number
VFM0010
2.3 Calibration tape
Manufacturers of video tape recorders designed for this format specification may sell
calibration tapes meeting the following requirements.*
2.3.1 Record locations and dimensions
Tolerances shown in table 5 or table 6 should be reduced by 50 %.
2.3.2 Calibration signals
Two classes of signals should be recorded on the calibration tapes.
a) A series of conventional test signals.
100 % colour bars
Video:
Audio: 1 kHz tone at -20 dB below full level
1 kHz tone at reference level
Cue:
10 kHz tone at reference level
A signal of constant recorded frequency (i.e., Y the Nyquist frequency) with only
b)
tracks of field 0, segment 0 for the purpose of mechanical alignment.
2.3.3 Purchase
The calibration tape may be purchased from the following manufacturers:
Company
Matsushita Electric Industrial Co., Ltd.
Audio and Video Systems Division
2-15, Matsuba-cho, Kadoma-city,
Osaka 571 Japan.
TEL.: +81-6-901-1161
This information is given for the convenience of users of this International Standard and does not constitute
an endorsement by the 1EC of the product named. Equivalent products may be used if they can be shown
to lead to the same results.

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1327 ©IEC:1995 – 21 –
FAX.: +81-6-905-4048
TLX.: +81-6-529-4690
Part number
for 525/60 system Conventional test: VFM6080EC
Mechanical alignment: VFM6081 EC
VFM6180EC
for 625/50 system Conventional test:
Mechanical alignment: VFM6181EC
Video tape cassette
3.1
Mechanical parameters
3.1.1 Cassette dimensions
3.1.1.1 The dimensions of the three different cassettes used for recording shall be in
accordance with figures 3 to 23. Small and medium size cassettes shall utilize reels with
30 mm and 50 mm hub diameter sizes. Large size cassettes shall use reels with 44 mm
hub diameter.
Both hubs within the cassette shall be of the same size.
3.1.1.2 General tolerances for dimensions, except those for which tolerances are other-
wise specified, shall be as indicated in table 1.
Table 1 – Mechanical tolerances
Over To Tolerance
mm
mm mm
0 4 ±0,15
4 16 ±0,2
16 63 ± 0,25
± 0,3
63 250
250 ± 0,4
3.1.2 Identification of cassettes
The three sizes of cassettes shall be identified as:
– small S;
– medium M;
– large L.
3.1.3 Tape length, thickness and play times
The tape length, thickness and play time for the three sizes of cassettes shall be as
indicated in table 2.

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1327 © IEC:1995 - 23 -
Table 2 - Tape thickness, length and play times of S, M, L cassettes
Play time
Tape cassette Hub diameter Thickness Length
m min
mm
11111
64/50
S 30 11/14 325/254
204/163 40/32
50 11/14
125/95
M 30 11/14 632/481
50 11/14 506/405 100/80
245/185
L 44 11/14 1 237/935
3.1.4 Coating face
The magnetic coating on the tape shall face out of the cassette as specified in figures 3
to 5.
3.1.5 Datum planes
3.1.5.1 Datum plane Z shall be determined by datum areas A, B and C, as specified in
figures 6 to 8.
3.1.5.2 Datum C need not correspond with a fastener.
rthogonal to datum plane Z and shall run through the
3.1.5.3 Datum plane X shall be o
centre of datum hole (a) and datum hole (b) as specified in figures 9 to 11.
3.1.5.4 Datum plane Y shall be orthogonal to both datum plane X and datum plane Z and
shall run through the centre of datum hole (a) as specified in figures 9 to 11.
3.1.5.5 The light path shall be as specified in figures 12 to 14.
3.1.5.6 The cassette positioning surface area shall be as specified in figures 15 to 17.
3.1.6
Window and labels
3.1.6.1 Window and label areas shall be as specified in figures 18 to 20.
3.1.6.2 Labels attached to the cassette shall not extend beyond the external dimensions
as shown in figures 18 to 20.
3.1.6.3 Labels shall not hide the identification holes of the users or the manufacturers.
3.1.6.4 Labels shall not interfere with the hub drive and support mechanism.

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1327 ©IEC:1995 - 25 -
3.1.7
Identification holes
3.1.7.1 There shall be two sets of identification holes; one for use by the manufacturer,
and the other for the user.
3.1.7.2 The dimension and location of manufacturers' coding holes, detailed in figures 21
to 23 shall be defined as follows.
Holes (1), (2) and (3) shall be used in combination to indicate tape thickness and diameter
of hub according to the following logic table:
Hole numbers: (1) (2) (3)
0 0 0 11 gm tape, 30 mm diameter hub
11 gm tape, 50 mm diameter hub
0 0 1
0 1 0 14 pm tape, 30 mm diameter hub
0 1 1 14 gm tape, 50 mm diameter hub
1 0 0 undefined/reserved
1 0 1 undefined/reserved
undefined/reserved
1 1 0
1 1 1 undefined/reserved
A "1" in the above table indicates that the indicator tab is removed or open, which results
in an undetected state by the recorder/player sensor mechanism.
3.1.7.3 The dimension and location of the users' coding holes, detailed in figures 21
to 23 shall be defined as follows.
When a "1" state exists, the user holes shall identify the following conditions:
- user hole (a): total record lock out (audio/video/cue/time and control code/control
track);
- user hole (b): video and control track record lock out;
- user hole (c): reserved and undefined.
3.1.7.4 The user plug mechanism shall withstand an axial force of 0,5 N.
3.1.7.5 The colour of the user plugs shall be red.
3.1.8 Leader/trailer tape
3.1.8.1 The cassette shall include leader and trailer tape. When attached to the hub, the
lengths between the splice point and the clamping point on the reel hub shall be as
specified in table 3.

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1327 © IEC:1995
– 27 –
Table 3 – Length of leader and trailer tape
Cassette size
Hub diameter
S, M L
mm mm
mm
30 165±10
44 — 180 ± 10
50 155 ± 10 —
3.1.8.2 The leader/trailer tape material shall be polyester or equivalent having a trans-
missivity of at least 50 % when measured with a 800 nm to 900 nm light source.
3.1.8.3 When attached to the hub, the leader/trailer tape shall not separate when
subjected to a force of 20 N or less.
3.1.8.4 The width of the leader/trailer tape shall be 12,650 mm ± 0,020 mm.
3.1.8.5 The thickness of the leader/trailer tape shall be 141.1m to 36 p.m.
3.1.8.6 The splicing tape used to attach the leader/trailer tape shall be applied to the
non-magnetic coated side.
3.1.9 Reels
3.1.9.1 The dimensions of the reels and the relationship between the reels and reel
tables are specified in figures 24 to 31.
3.1.9.2 The reels shall be locked automatically when the cassette is removed from the
recorder/player.
The number and shape of teeth as well as the locking mechanism are not specified.
3.1.9.3 When a cassette is inserted into the recorder/player, the reels shall be unlocked
automatically by the light house as specified in figure 32.
The force needed to release the reel lock shall be less than 1 N.
3.1.9.4 The reels shall be held in position by a reel spring with a force as shown in
table 4, when the height of the reel table support is 2,0 mm ± 0,1 mm from datum plane Z
as shown in figures 29 to 31.

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1327 ©IEC:1995 -
29 -
Table 4 - Reel spring force
Cassette size Force
N
S 2, ±0,3
M 3,5 ± 0,3
4,0 ± 0,3
L
3.1.10 Lid
3.1.10.1 The lid shall be unlocked and opened by the recorder/player when the cassette
is inserted.
3.1.10.1.1 The lid shall be unlocked by a force of less than 0,3 N exerted upon the
release pin, as specified in figures 33 and 35.
3.1.10.1.2 The inner door shall be lifted by the recorder/player to the position shown in
figure 36.
3.1.10.1.3 The outer door shall be lifted by the recorder/player to the position shown in
figures 37 and 39.
3.1.10.2 The minimum space of cassette for the VTR loading mechanism shall be as
shown in figure 40.
3.1.10.3 The outer door when open shall not exceed 37 mm with respect to datum plane
Z, and the angle y between the front side su rface and datum plane X shall be 93° ± 2°, as
specified in figure 41.
3.1.10.4 When the cassette is removed from the recorder/player, the lid shall lock
automatically.
3.1.10.5 The maximum force to open the lid shall be less than 1 N for S and M
cassettes and 1,5 N for L cassette up to the 25 mm minimum height defined in figure 41.
3.1.10.6 The force required to open the lid shall be applied 93° ± 2° to the datum
plane Z at the opening and closing areas as shown in figures 36 to 41.
3.2 Video tape specification
3.2.1 Base
The base material shall be polyester or equivalent.
3.2.2 Width
The tape width shall be 12,650 mm ± 0,008 mm.

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1327 ©IEC:1995 - 31 -
The tape, covered with glass, is measured without tension at a minimum of five different
positions along the tape using a calibrated comparator having an accuracy of 1/1 000 mm
= 1 gm. The tape width is defined as the average of the five readings.
3.2.3 Width fluctuation
Tape width fluctuation shall not exceed 5 gm peak-to-peak. Measurement of tape width
fluctuation shall be over a tape length of 900 mm at the beginning of tape winding.
The value of tape width fluctuation shall be evaluated by measuring the tape width
at 10 points, each separated by a distance of 100 mm.
3.2.4
Reference edge straightness
The reference edge straightness maximum deviation is 6 µm peak-to-peak. Edge straight-
ness fluctuation is measured at the edge of a moving tape guided by three guides having
contact on the same edge and having a distance of 85 mm from the first to second guide
and 85 mm from the second to third guide. Edge measurements are averaged over 10 mm
lengths and are made 5 mm from the midpoint between the first and second guide,
towards the first guide.
3.2.5 Tape thickness
The thickness of the tape (including all coatings) shall be, respectively, 10,2 µm to
11,0 gm and 13,0 p.m to 14,0 gm.
3.2.6 Transmissivity
Transmissivity shall be less than 5 %, measured over the range of wavelengths 800 nm to
900 nm.
3.2.7 Offset yield strength
The offset yield strength shall be greater than 9 N for 11 pm tape and 10 N for 14 p.m tape.
The force to produce 0,2 % tangential elongation of a 1 000 mm test sample with a pull
rate of a 10 mm/min shall be used to confirm the offset yield strength. The line beginning
at 0,2 % elongation parallel to the initial tangential slope is drawn and then read the point
of intersection of the line and the stress-strain curve.
3.2.8 Magnetic coating
The magnetic tape used shall have a coating of metal particles or equivalent.
3.2.9 Coating coercivity
The coating coercivity shall be a class 1 600 Oe (127 300 A/m), with an applied field of
397 800 A/m as measured by a 50 Hz or 60 Hz B-H meter or vibrating sample magneto-
meter (VSM).
3.2.10 Particle orientation
The metal particles shall be longitudinally oriented or equivalent.

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1327 ©IEC:1995 – 33
4 Helical recordings
4.1
Tape speed
The tape speed is 83,880 mm/s. The tape speed tolerance is ±0,2 %.
4.2 Erase head and record location and dimensions
4.2.1 Erase head
The format requires full width erase for continuous recording and flying erase for insert
editing.
4.2.2 Record location and dimensions
Record location and dimensions for continuous recording shall be as specified in figures
42 and 43, and table 12 (525/60 systems) or table 13 (625/50 systems). In recording,
sector locations on each helical track shall be contained within the tolerance specified in
table 12 or table 13 and figure 42.
4.2.3
Reference edge
The reference edge of the tape for dimensions specified in this standard shall be the lower
edge as shown in figure 42. The magnetic coating, with the direction of tape travel as
shown in figure 42, is on the side facing the observer.
Measuring techniques are shown in annex A.
4.2.4 Track pitch
As indicated in figure 42, this standard anticipates a zero guard band between recorded
tracks, and the record head width should be equivalent to the track pitch of 20 gm (525/60
system) or 18 gm (625/50 system).
The scanner head configuration should be chosen such that the recorded track widths are
contained within the limits of 18 gm to 22 gm (525/60 system) or 16 gm to 20 pm (625/50
system).
4.2.5 Flying erase heads
In insert editing, this standard provides a guard band of 2 gm (nominal) between the pre-
viously recorded track and the inserted track at editing points only.
A typical track pattern for insert editing is shown in figure B.1 of annex B.
4.3 Helical track record tolerance zones
The lower edges of any four consecutive tracks starting at the first track in each video
frame shall be contained within the pattern of the four tolerance zones established in
figure 44 (525/60 system) or figure 45 (625/50 system).

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1327 ©IEC:1995 - 35 -
Each zone is defined by two parallel lines which are inclined at an angle of 4,919 2°
(525/60 system) or 4,917 3° (625/50 system) basic, with respect to the tape reference
edge.
The centre lines of all zones shall be spaced apart 0,020 0 mm basic (525/60 system) or
0,018 0 mm basic (625/50 system). The width of zones 1, 3 and 4 shall be 0,006 mm basic
for both systems. The width of zone 2 shall be 0,004 mm basic for both systems. These
zones are established to contain track angle errors, track straightness errors and vertical
head offset tolerance.
Measuring techniques are shown in annex A.
4.4 Relative positions of recorded signals
4.4.1
Relative positions of the longitudinal tracks
Audio, video, ancillary data, tracking control, time and control code and cue track with
information intended to be time coincident shall be positioned as shown in figures 42
and 43.
4.4.2 Helical/control track relationship
The spatial relationship between the cue track record, time and control code record,
control track record and helical tracks are specified in figures 42 and 43.
4.4.3
Programme area reference point
The programme area reference point is determined by the intersection of a line parallel to
the reference edge of the tape at the distance Y from the reference edge and the centre
line of the first track in each video field (segment 0, track 0).
The end of the preamble and start of the video sector shall be recorded at the programme
area reference point and the tolerance is dimension X1. The locations are shown in figures
42 and 43, dimensions X1 and Y are given in table 12 (525/60 system) or table 13 (625/50
system). The relationship between sectors and contents of each sector is specified in 5.3
to 5.5.
4.5 Gap azimuth
4.5.1 Cue track, control track, time and control code track
The azimuth angle of the cue, control track and time and control code head gaps used to
produce longitudinal track records shall be perpendicular to the track record.
4.5.2 Helical track
The azimuth of the head gaps used for the helical track recording shall be inclined at
as specified in table 12 (525/60 system) or table 13 (625/50 system)
angles ao and ai
perpendicular to the helical track record. The azimuth of the first track of every field
(segment 0, track 0) shall be oriented in the counterclockwise direction with respect to the
line perpendicular to the track direction when viewed from the side of the tape containing
the magnetic record.

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1327 ©IEC:1995 – 37 –
4.6 Transport and scanner
The effective drum diameter, tape tension, helix angle and tape speed taken together
determine the track angle. Different methods of design and/or variations in drum diameter
and tape tension can produce equivalent recordings for interchange purposes.
A possible configuration of the transport uses a scanner with an effective diameter of
76,000 mm. Scanner ro
...