EN 60961:1994

SLOVENSKI STANDARD
01-april-1999
Helical-scan video tape cassette system using 12,65 mm (0,5 in) magnetic tape on
type L (IEC 60961:1993)
Helical-scan video tape cassette system using 12,65 mm (0,5 in) magnetic tape on type
L
Video-Bandkassettensystem mit Schrägspuraufzeichnung auf Magnetband 12,65 mm
(0,5 in) L-Format
Système de magnétoscope à cassette à balayage hélicoïdal utilisant la bande
magnétique de 12,65 mm (0,5 in) de format L
Ta slovenski standard je istoveten z: EN 60961:1994
ICS:
33.160.40 Video sistemi Video systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME CEI
INTERNATIONALE IEC
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
1993-12
Système de magnétoscope à cassette
à balayage hélicoïdal utilisant
la bande magnétique de 12,65 mm (0,5 in)
de format L
Helical-scan video tape cassette
system using 12,65 mm (0,5 in)
magnetic tape on type L
© CEI 1993 Droits de reproduction réservés — Copyright — all rights reserved
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For price, see current catalogue

961 ©IEC:1993 - 3 -
CONTENTS
Page
FOREWORD 9
Clause
SECTION ONE: GENERAL
1 Scope
11 2 Normative references
11 3 Environment and test conditions
Environment
3.1
3.2 Reference tape
Calibration tape 3.3
SECTION TWO: VIDEO TAPE AND VIDEO TAPE CASSETTE
SECTION THREE: VIDEO CASSETTE RECORDERS

4 Definitions of terms
Scanner 4.1
4.2 Drum
15 4.3 Upper drum
4.4 Lower drum
15 4.5 Effective drum diameter
4.6 Helix angle
4.7 Track angle
17 4.8 Centre span tension
4.9 Wrap angle
4.10 Lead signal overlap
5 Scanner pole-tips
17 5.1 Pole-tip projection
5.2 Luminance pole-tips
17 5.3 Colour-recording pole-tips
5.4 Erase pole-tips 19
5.5 Channel identification
Helix angle 19
7 Drum diameter and tape tension
19 7.1 Actual upper drum diameter
7.2 Actual lower drum diameter
7.3 Upper drum 19
21 7.4 Centre span tension
961 © I EC:1993 – 5 –
Page
Clause
Dimensions and location of records 8
Test environment 8.1
21 8.2 Tape speed
Recording locations and dimensions 8.3
8.4 Curvature of video recordings
Relative positions of recorded signals 8.5
23 8.6 Gap azimuth
9 Luminance and colour-recording system
10 Recording characteristics
SECTION FOUR: RECORDING CHARACTERISTICS
11 Video recording
25 11.1 Luminance channel
31 11.2 Chrominance channel
35 11.3 Decoding and colour-field identification
37 12 Longitudinal audio signal recording (channels 1 and 2)
12.1 Reference levels
37 12.2 Frequency response
12.3 Track usage
41 13 FM audio signal recording (channels 3 and 4)
13.1 Signal processing
13.2 Reference levels
43 13.3 Noise reduction
13.4 Frequency modulation
43 13.5 Recording current
13.6 Track usage
45 14 Time and control code recording
14.1 Designated track for time and control code
45 14.2 Recording method
45 15 Tracking control recording
45 15.1 Tracking control signal
47 15.2 Tracking control and video timing
15.3 Recording method
SECTION FIVE: TYPE–L FORMAT VIDEO TAPE AND VIDEO TAPE CASSETTE
47 16 Mechanical characteristics of video tape cassette
16.1 Cassette outside dimensions
16.2 Datum planes
- 7 -
961 ©IEC:1993
Page
Clause
16.3 Window area and label area
16.4 Manufacturer's identification holes
16.5 Safety tab and safety plug 49
16.6 Reel
16.7 Cassette lid
17 Magnetic tape
51 17.1 Type of magnetic tape
53 17.2 Tape width
53 17.3 Tape thickness and length
17.4 Coercivity
17.5 Transmissivity
53 17.6 Offset yield strength
55 17.7 Residual elongation
55 17.8 Magnetic orientation
18 Leader tape/trailer tape
18.1 Mechanical characteristics
18.2 Leader tape and trailer tape dimensions
18.3 Offset yield strength
18.4 Splicing break strength
Figures
Annexes
135 A Cross tape track measurement technique
Reference tapes B
- 9 -
961 ©IEC:1993
INTERNATIONAL ELECTROTECHNICAL COMMISSION
HELICAL-SCAN VIDEO TAPE CASSETTE SYSTEM
USING 12,65 mm (0,5 in) MAGNETIC TAPE
ON TYPE L
FOREWORD
The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
1)
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.
International Standard IEC 961 has been prepared by sub-committee 60B: Video
recording, of IEC technical committee 60: Recording.
This second edition cancels and replaces the first edition published in 1989.
The text of this standard is based on the following documents:
DIS Report on Voting
60B(CO)152 60B(CO)168
Full information on the voting for the approval of this standard can be found in the repo rt
on voting indicated in the above table.
Annexes A and B are for information only.

961 ©IEC:1993 - 11 -
HELICAL-SCAN VIDEO TAPE CASSETTE SYSTEM
USING 12,65 mm (0,5 in) MAGNETIC TAPE
ON TYPE L
SECTION ONE: GENERAL
1 Scope
This International Standard applies to magnetic video recording and/or reproduction using
12,65 mm (0,5 in) tape cassettes on helical-scan video cassette recorders suitable for
broadcast applications.
This standard specifies two recording modes. MODE I uses oxide particle tape, MODE II
uses metal particle tape and permits frequency modulated (FM) audio signals to be
recorded. The standard defines the electrical and mechanical characteristics of equipment
which will provide for interchangeability of recorded casse ttes. The requirements given are
related to 525 line-60 field and/or 625 line-50 field systems.
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 editions indicated were valid. All normative documents are subject to revision, and
parties 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 94-1: 1981, Magnetic tape sound recording and reproducing systems - Part 1:
General conditions and requirements
IEC 268-17: 1990, Sound system equipment - Part 17: Standard volume indicators
IEC 461: 1986, Time and control code for video tape recorders
IEC 767: 1983, Helical-scan video tape cassette system using 12,65 mm (0,5 in) magnetic
tape on type beta format
CCIR Repo rt 624-4: Characteristics of television systems
3 Environment and test conditions
3.1 Environment
Test and measurement made on the system to check the requirements of this standard
shall be carried out under the following conditions.

- 13 -
961©IEC:1993
Temperature (drum diameter): 20 °C ± 0,5 °C
20 °C ± 1 °C
Temperature (all other tests):
48%to52%
Relative humidity:
86 kPa to 106 kPa
Barometric pressure:
24 h
Conditioning before testing:
3.2 Reference tape
Blank tape to be used for reference recordings may be purchased from the manufacturers
listed in annex B. The electromagnetic compatibility parameters and their specifications
should be specified by the manufacturers and controlled accordingly.
Model name:
a) IEC L-format reference tape for MODE I;
IEC L-format reference tape for MODE II.
b)
Electromagnetic compatibility parameters and their specifications are indicated in
annex B.
3.3 Calibration tape
Calibration tapes which have satisfied the following requirements will be available from
manufacturers of video tape recorders and players in accordance with this format specifi-
cation.
Record locations and dimensions
3.3.1
For calibration tapes intended for the purpose of calibrating the mechanical accuracy of
the recorder or player, in accordance with this format specification, a 50 % reduction in the
tolerances shown in table 7 should, in general, be applied. If necessary, the record
locations and dimensions can be specially modified for certain calibration tapes in order to
avoid calibration error or to aid calibration.
3.3.2 Calibration signals
Two classes of signals should be recorded on the calibration tapes:
a) a series of conventional test signals for analogue component video tape recorders
Longitudinal audio
Video
- 1 kHz 0 VU
Colour bars (75 % or 100 %) -
- 15 kHz or 10 kHz 0 VU
- Multi-burst
- 40 Hz -20 VU
- Bow-tie (50 %)
-20 VU
- 1 kHz
- Pulse and bar
- 7 kHz -20 VU
FM audio
- 10 kHz -20 VU
- 400 Hz, 25 kHz deviation
-20 VU
- 400 Hz, 75 kHz deviation - 15 kHz

961 ©IEC:1993 –15 –
b) special test signals developed by each manufacturer for product alignment. These
signals are not universally applicable to all manufacturers' products, and will not be
specified.
SECTION TWO: VIDEO TAPE AND VIDEO TAPE CASSETTE
This video tape recording system specifies the use of video tape and video tape cassette
in the BETA-format as delineated in sections two and four of IEC 767 or the use of video
tape and video tape cassette in the type-L format as delineated in section five of this
standard, which is newly specified to provide all-inclusive specifications of video tape and
video tape cassette for MODE Il recordings and/or long-playing operations including
current video tape and video tape cassette (see 16.1 through 18.4 of this standard).
SECTION THREE: VIDEO CASSETTE RECORDERS
4 Definitions of terms
The following definitions are given to assist in the correct understanding of this Inter-
national Standard.
4.1 Scanner
The mechanical assembly containing a drum, rotating pole-tips and tape-guiding elements.
It is used to record and reproduce video tape recordings.
4.2 Drum
The circular cylinder around which tape is at least partially wrapped in order to form the
head-to-tape inte rface of a video tape recording system.
4.3 Upper drum
That part of the drum in a helical-scan video recording system which does not come into
contact with the reference edge of the tape.
4.4 Lower drum
That part of the drum in a helical-scan video recording system which comes into contact
with the reference edge of the tape and usually contains tape-guiding elements.
4.5 Effective drum diameter
The value of drum diameter which, when used in theoretical calculations, will correspond
to the actual video record produced in a helical-scan video tape recording system. The
effective value is equal to or greater than the actual diameter.

– 17 –
961 © I EC:1993
4.6 Helix angle
The angle formed between the path of the rotating pole-tips and the tape-reference-edge
guiding system on the scanner of a helical-scan video tape recording system.
4.7 Track angle
The angle of the recorded video track with respect to the reference edge of the tape in a
helical video tape recording.
4.8 Centre span tension
The calculated value of tape tension at a point midway between tape entrance and exit
guides of the scanner in a video tape recording system.
4.9 Wrap angle
The angle at the centre of the drum rotation subtended by the line of contact between the
drum and the reference edge of the tape.
4.10 Lead signal overlap
That portion of the helical record which is required to provide a duplicate (overlap)
recording.
5 Scanner pole-tips
There shall be four circumferential pole-tip locations as shown in figure 1 (top view).
5.1 Pole-tip projection
mm, measured from the outer surface
Each pole-tip projection shall be radially 0,04
+0,0,
of the upper drum to the end of the pole-tip.
5.2 Luminance pole-tips
180° ± 0,003° shall be provided for recording the
Two pole-tips circumferentially spaced at
luminance signal.
5.3 Colour-recording pole-tips
Each luminance pole-tip shall have associated with it a pole-tip for recording the time-
multiplexed colour signals and, when applicable, the FM audio signals.
A colour-recording pole-tip shall be located at a chordal distance of 4,396 mm ± 0,010 mm
in a counter-rotational direction from its associated luminance pole-tip, as shown in fgure 2,
mm
and shall be axially displaced from its associated luminance pole-tip by 0,0745
mm, in a direction away from the reference edge of the tape as shown in figure 2.
± 0,003
961 ©IEC:1993 – 19 –
5.4 Erase pole-tips
If the erase pole-tips are employed, each luminance/colour-recording pole-tip pair shall
have an associated erase pole-tip located at any angle with respect to the luminance pole-
tip of the pair, in the direction of rotation as shown in figure 1.
5.5 Channel identification
Suitable means shall be provided, such as a pulse generator producing one pulse per
drum revolution, to permit the identification of the luminance/colour-recording pole-tip
pair which records field 1. This pair shall be identified as channel 1, and the remaining
pair shall be identified as channel 2.
6 Helix angle
The helix angle shall be 4,600° ± 0,003°.
7 Drum diameter and tape tension
Effective drum diameter, tape tension, helix angle, and tape speed completely determine
the video record track angle. Different methods of design and/or minor variations in drum
diameter and tape tension shall produce equivalent recordings for interchange purposes.
Values and operating conditions specified in this clause will produce the reference value
of track angle.
7.1
Actual upper drum diameter
ô,008 (2,933+00,00032
The actual upper drum diameter shall be 74,487 mm in). New techno-
logies and techniques are enabling compatible and interchangeable tapes to be produced
by recorders in which some of the dimensions of the transport scanning mechanism are
significantly changed. This can enable recorders to be made smaller and lighter for
portable applications by the use of a smaller scanning drum assembly. Such an approach
has been used for ENG applications.
7.2 Actual lower drum diameter
+0,000 +0,00000
74,487 The actual lower drum diameter shall be mm (2,933 in). New techno-
-0,008 0 00032
logies and techniques are enabling compatible and interchangeable tapes to be produced
by recorders in which some of the dimensions of the transport scanning mechanism are
significantly changed. This can enable recorders to be made smaller and lighter for
portable applications by the use of a smaller scanning drum assembly. Such an approach
has been used for ENG applications.
7.3 Upper drum
The upper drum shall rotate in synchronism with the video head tips.

- 21 -
961 © I EC:1993
7.4 Centre span tension
The centre span tension shall be 0,46 N ± 0,05 N.
8 Dimensions and location of records
This clause specifies the dimensions and locations of the video, audio and tracking control
records.
Test environment
8.1
8.1.1 In addition to the general environmental requirements of clause 3, the following
additional conditions shall be met in order to meet requirements of clause 8:
tape tension: 0,46 N ± 0,05 N.
8.1.2 Conditioning before recording and testing
Environmental: stabilized at the measurement conditions.
Tape tension: wound on a reel at 0,56 N ± 0,20 N.
8.1.3 The reference edge of the tape for dimensions in this standard shall be the lower
edge as shown in figures 3, 4a and 4b. The magnetic coating of the tape faces the
observer in all figures.
Tape speed
8.2
8.2.1 The tape speed shall be 118,582 mm/s ± 0,2 mm/s for 525 line-60 field systems.
8.2.2 The tape speed shall be 101,510 mm/s ± 0,2 mm/s for 625 line-50 field systems.
8.3 Recording locations and dimensions
8.3.1 Recording locations and dimensions shall be as specified in figures 3, 4a and 4b
and in table 7.
and 0 are shown for reference purposes only.
8.3.2 Dimensions P, R, W
rt ,
The actual value of these dimensions is determined by the parameters of the transpo
the tape speed and their tolerances. Direct measurement of the actual value of these
Q may be impractical; therefore, these dimensions should be
dimensions and dimension
made by an indirect measurement method, such as that specified in 8.4.
8.4 Curvature of video recordings
The edge of the video recording shall be contained within two parallel straight lines
0,010 mm apa rt .
961 ©IEC:1993 – 23 –
Relative positions of recorded signals
8.5
8.5.1 Video luminance, video chrominance, tracking control, audio and time code signals
with information intended to be time coincident shall be positioned as shown in figures 4a
and 4b.
8.5.2 As shown in figures 4a and 4b, even-numbered fields have a different video
luminance and video chrominance phasing, due to the odd number of lines in a television
frame.
Gap azimuth
8.6
8.6.1 The azimuth of the audio, tracking control and time code head gaps used to
produce longitudinal track records shall be perpendicular to the direction of relative head-
to-tape motion.
8.6.2 The azimuth of the video head gaps for the luminance signal shall be –15° 15' and
signal shall be +15° 15' to the perpendicular to the direction of head
for the chrominance
motion.
9 Luminance and colour-recording system
Each pass of a luminance/colour-recording pole-tip pair shall record one television field,
plus an overlap.
10 Recording characteristics
The recording characteristics of video cassette recorders shall be in accordance with the
requirements specified in section four.
SECTION FOUR: RECORDING CHARACTERISTICS
11 Video recording
The video recording system shall provide separate and distinct signal paths for the
luminance and chrominance components. These component signals shall be recorded on
two separate tracks, designated as the Y track for the luminance signal, and the C track
for the chrominance signal. The C track shall record both R-Y and B-Y colour difference
signals in the form of a compressed time division multiplexed signal and, when applicable,
FM audio signals. Monochrome signals shall be recorded on the Y track, with the C track
recording only a blanking level signal and horizontal timing pulse.
Two modes of operation are defined for the following tape types:
oxide particle tape: MODE I;
metal particle tape: MODE II.
Sensing of tape type shall be automatic by means of a sensing hole in the cassette as
described in section five.
- 25 -
961 ©IEC:1993
11.1 Luminance channel
11.1.1 Signal processing
A signal processing system as specified in this clause shall contain in the order of the
signal flow the following elements:
rtion of the luminance signal.
11.1.1.1 A means of modifying the sync po
ical interval subcarrier in MODE II when the signal to
rt
11.1.1.2 A means of inserting a ve
be recorded has been decoded from a composite signal source which is defined in
SECAM
ical interval subcarrier (VISC) is not recorded in the
CCIR repo rt 624-4. The ve rt
system and shall be optional in MODE I.
11.1.1.3 A video detail enhancement process.
11.1.1.4 A video pre-emphasis network.
11.1.1.5 A means of clipping the video signal after pre-emphasis.
11.1.1.6 A linear frequency modulator having constant deviation with respect to the ampli-
tude of the modulating frequencies.
11.1.1.7 An amplifier of the frequency modulated carrier signal to provide alternating
current drives to the Y channel record heads.
11.1.2 Modification of the sync portion
A means shall be used to modify the pulse width and amplitude of the horizontal sync
ion as shown in figures 5a and 5b.
port
Luminance detail enhancement
11.1.3
The video signal shall receive detail enhancement with the characteristics shown in
table 1.
961 © I EC:1993 - 27 -
Table 1 - Detail enhancement output (dB)
Input
Frequency dB
Hz
-30 -20 -15 -10 -5 0
0,2
200 k 0,4 0,4 0,4 0,4 0,3
500 k 1,9 1,7 1,7 1,4 0,8 0,4
0,7
1,0 M 4,6 4,0 3,5 2,4 1,3
1,5 M 6,7 4,6 3,0 1,6 0,9
5,6
3,3 1,1
2,0 M 8,0 6,6 4,9 1,8
3,0 M 9,5 7,5 5,3 3,6 2,2 1,3
1,4
4,0 M 9,9 7,6 5,3 3,6 2,2
5,0 M 9,9 7,3 5,1 3,3 2,0 1,2
NOTES
1 The video signal input level, including synchronization tip, is 1,0 Vpp.
The play-back response is such that the recording response is compensated during play-back.
at 3,5 MHz prior to
3 The phase of side chain signal shall be equal to the phase of input signal 43 1
t2
mixing.
(Di Input Output
o
0 0
High pass Low pass
Limiter
filter filter
MC 288193
11.1.4 Luminance pre-emphasis
The pre-emphasis is defined by the frequency and phase characteristics of the network
shown in figure 6, when fed from a zero impedance source, and feeding an infinite
impedance load.
11.1.5
Amplitude clipping
For an input signal where synchronization tip is at 0 % and peak white at 100 %, any
positive or negative amplitude excursion exceeding the levels shown in table 2 shall be
clipped.
961 ©IEC:1993 29 -
-
Table 2 - Amplitude clipping (luminance)
525 line-60 field 625 line-50 field
MODEI MODE II MODEI MODE II
+250 % +260 % +250 % +300 %
Nominal
Positive excursion limit
Maximum +255 % +265 % +255 % +305 %
-65 % -100 % -65 % -150%
Nominal
Negative excursion limit
Maximum -70 % -105 % -70 % -155 %
11.1.6
Recorded carrier frequency
Carrier frequency corresponding to reference levels of the modified luminance signal shall
be as defined in table 3.
Table 3 - Recorded carrier frequency (luminance)
525 line-60 field system MODE I MODE II
7,7 MHz
Peak white 6,5 MHz
50 % level 5,7 MHz 7,0 MHz
6,27 MHz ± 0,05 MHz
Blanking 4,97 MHz ± 0,05 MHz
5,7 MHz
Synchronization tip 4,4 MHz
Frequency deviation 1,43 MHz ± 0,05 MHz 1,43 MHz ± 0,05 MHz
625 line-50 field system MODE I MODE II
8,8 MHz
Peak white 6,4 MHz
8,1 MHz
50 % level 5,7 MHz
Blanking 5,00 MHz ± 0,05 MHz 7,40 MHz ± 0,05 MHz
6,8 MHz
Synchronization tip 4,4 MHz
Frequency deviation 1,40 MHz ± 0,05 MHz 1,40 MHz ± 0,05 MHz
NOTE - Frequency deviation is between peak white and blanking level.
11.1.7 Record head current
11.1.7.1 The amplitude of the recording current for the Y track shall be such that a
maximum level of remaining flux on tape is produced when recording a Y signal with a
50 % average picture-level.
11.1.7.2 The amplitude of the Y track record current shall decrease with increasing
frequency in the range 2 MHz to 10 MHz according to a straight line contained within limit
lines as shown in figure 11.
This method assures optimum recording irrespective of video head material.

961 © I EC:1993 – 31 –
11.2
Chrominance channel
11.2.1 Signal processing
A signal processing system as specified in this clause shall contain in the order of the
signal flow the following elements.
11.2.1.1 A means of compressing the time scale of the R-Y and B-Y signals over a period
of one horizontal line such that they may be time multiplexed into one horizontal line.
11.2.1.2 A means of adding a horizontal timing pulse.
11.2.1.3 A video detail enhancement process.
11.2.1.4 A video pre-emphasis network.
11.2.1.5 A means of clipping the video signal after pre-emphasis.
11.2.1.6 A linear frequency modulator having constant deviation with respect to the
amplitude of the modulating frequencies.
11.2.1.7 A high pass filter to reduce the amplitude of the low-frequency components of
the FM chrominance signal.
11.2.1.8
A means of combining the frequency-modulated audio signal, and the
frequency-modulated chrominance signal in MODE II when the FM audio signals are
present.
11.2.1.9 An amplifier of the frequency-modulated carrier signal to provide alternating
current drive to the C channel recording heads.
11.2.2 Time compression and multiplexing
11.2.2.1 The R-Y and B-Y signals shall each be compressed into a half time scale. The
starting point of compression shall be as shown in figures 7a and 7b.
11.2.2.2 The compressed R-Y and B-Y signals shall be multiplexed alternately as
shown in figure
8.
11.2.2.3 The compressed and multiplexed R-Y and B-Y signals shall be delayed by one
horizontal line with respect to the luminance signal.
11.2.3 Addition of a horizontal timing pulse
A horizontal timing pulse shall be added to the compressed and multiplexed R-Y and B-Y
signals as shown in figures 7a and 7b. The fall time of the timing pulse shall have an
approximate Gaussian shape with a fall time of 220 ns.
11.2.4 Chrominance detail enhancement
The video signal shall receive detail enhancement with the characteristics shown in
table 1.
961 ©IEC:1993 - 33 -
11.2.5
Chrominance pre-emphasis
The pre-emphasis is defined by the frequency and phase characteristics of the network
as shown in figure 6, when fed from a zero impedance source and feeding an infinite
impedance load.
11.2.6 Amplitude clipping
For a signal with timing pulse tip at -105 % and nominal positive peak at +50 % corre-
sponding with "100/7,5/77/7,5 colour bars" of the 525 line-60 field system, or at -120 %
and nominal positive peak at +50 % corresponding with "100/0/75/0 colour bars" of the
625 line-50 field system, any positive or negative amplitude excursions exceeding the le-
vels shown in table 4 shall be clipped.
Table 4 - Amplitude clipping (chrominance)
525 line-60 field 625 line-50 field
MODEI MODE II MODE I MODE II
Nominal +175 % +230 % +175 % +260 %
Positive excursion limit
Maximum +180 % +235 % +180 % +265 %
Nominal —305 % —305 % —300 % —380%
Negative excursion limit
% —310 % —305 % —385 %
Maximum —310
11.2.7
Recorded carrier frequency
Carrier frequencies corresponding to reference levels of the compressed colour difference
signal shall be as defined in table 5.
Table 5 - Recorded carrier frequency (chrominance)
525 line-60 field system MODE I MODE II
(100/7,5/77/7,5 colour bars)
Peak positive video excursion 4,0 MHz 4,8 MHz
Peak negative video excursion 5,0 MHz 5,8 MHz
Blanking 4,5 MHz ± 0,05 MHz 5,3 MHz ± 0,05 MHz
Timing pulse tip 5,55 MHz 6,35 MHz
Frequency deviation 1,0 MHz ± 0,05 MHz 1,0 MHz ± 0,05 MHz
625 line-50 field system MODE I MODE II
(100/0/75/0 colour bars)
5,6 MHz
Peak positive video excursion 4,0 MHz
Peak negative video excursion 5,0 MHz 6,6 MHz
Blanking 4,5 MHz ± 0,05 MHz 6,1 MHz ± 0,05 MHz
Timing pulse tip 5,70 MHz 7,3 MHz
Frequency deviation 1,0 MHz ± 0,05 MHz 1,0 MHz ± 0,05 MHz
NOTE — Frequency deviation is between peak positive and negative video excursions.

961 ©IEC:1993 – 35 –
11.2.8
Record head current
11.2.8.1 The amplitude of the recording current for the C track shall be such that a
maximum flow level is produced when recording a C signal of blanking level.
11.2.8.2 The amplitude of the C track recording current shall decrease with increasing
frequency in the range 2 MHz to 10 MHz according to straight lines contained within limit
lines as shown in figure 11. This method assures optimum recording, irrespective of video
head material.
11.2.9 LF amplitude of the FM chrominance signal
In MODE II, if the FM audio signals are recorded, the chrominance signal shall be subject
to high-pass filtering prior to combining with the FM audio signals. The filter response is
shown in figure 12.
11.3 Decoding and colour-field identification
11.3.1 rtical interval subcarrier reference (VISC)
Ve
11.3.1.1 When operating in MODE II, a VISC signal shall be inserted on lines 11 and 274
(525 line-60 field) or lines 8 and 321 (625 line/50 field) of the Y signal prior to any signal
pre-emphasis. This signal shall only be present when the signal to be recorded is the
result of decoding a composite NTSC or PAL video signal with a coherent subcarrier.
The VISC signal is optional in MODE I.
11.3.1.2 The format of the VISC signal is shown in figures 13a and 13b.
11.3.1.3 The frequency of the VISC signal shall be equal to the subcarrier of each com-
posite video signal for the 525 line-60 field system, or half for the 625 line-50 field system.
11.3.1.4 The phase of the VISC signal for the NTSC system shall be within ±5° of the
burst phase of the composite NTSC video signal prior to decoding. The phase of the VISC
signal for the PAL system shall be such that the zero crossings denoting a half cycle of
VISC shall be coincident with the positive going zero crossings denoting a full cycle of sub-
carrier, within a tolerance of ±5° of subcarrier phase of the composite PAL video signal
prior to decoding.
11.3.2 Colour-field identification
11.3.2.1 When operating in MODE I and MODE II, a colour-field identification signal shall
be inserted into the chrominance as shown in figures 9a and 9b, when the signal to be
/SECAM video signal meeting
recorded is the result of decoding a composite NTSC or PAL
CCIR Report 624-4.
11.3.2.2 When operating in MODE II and recording signals that originated direct from
colour components, an identification signal shall identify a four-field sequence for the
525 line-60 field system, or an eight-field sequence for the 625 line-50 field system, as
shown in figures 9a and 9b.
961 © - 37 -
IEC:1993
11.3.2.3 When there is no way to detect the beginning of a four-field or an eight-field
colour sequence, the sequence may start arbitrarily.
11.3.2.4 When operating on MODE I, the colour-field identification signal referred to in
11.3.2.2 and 11.3.2.3 is optional.
12 Longitudinal audio signal recording (channels 1 and 2)
12.1 Reference levels
12.1.1
Recording method
All recordings shall be made using the anhysteretic (bias) method.
12.1.2
Recording and reproducing level indicator
Longitudinal audio signal recording and reproducing levels of the video tape recorder shall
be adjusted with reference to a standard volume indicator or equivalent as specified in IEC
268-17.
12.1.3 Recorder reference level
When a recording is made from a sinusoidal signal having a frequency of 1 000 Hz such
that the r.m.s. sho rt circuit tape flux per unit track width in the record is 100 nWb/m
Il of 525 line-60 field system, 100 ± 3 nWb/m for
± 3 nWb/m for MODE I and MODE
MODE I and 125 ± 3 nWb/m for MODE Il of 625 line-50 field system, of track width,
as defined in IEC 94-1, the recording volume indicator shall be adjusted to deflect to its
reference level (0 VU) scale mark.
12.2 Frequency response
12.2.1 Recorder flux/frequency response
When a tape is recorded from a constant voltage level applied to the input terminals of the
recording system, the relative tape flux level (short-circuit condition) L(13(f) versus fre-
quency, f / FI , shall be as given in the equation:
1 + (f I FI)2
Lri)(f) = 10 log10 dB
l Fh)2
1 + (f
where
L43 is the relative tape flux level
f is the frequency at which the response is being computed
Fi
is the low-frequency transition frequency, 50 Hz
Fh is the high-frequency transition frequency, 4 547 Hz (525 line-60 field), 3 183 Hz (625 line-50 field) in
MODE I and 4 547 Hz (525 line-60 field), 9 362 Hz (625 line-50 field) in MODE Il (with "feed in coil"
measurement method for core loss)

961 © I EC:1993 - 39 -
12.2.2
Reproducer flux/frequency response
When a tape recording having a short-circuit tape flux level versus frequency is repro-
duced as shown in 12.2.1, the output voltage level versus frequency of the reproducer
shall be constant.
12.2.3 Noise reduction characteristics
Noise reduction, if applied, shall have the encoding characteristics shown in table 6.
Table 6 - Audio noise reduction encoding characteristics (dB)
Tolerance: ±1,5 dB
Input level
Frequency dB
Hz
-60
0 -10 -20 -30 -40 -50
100 0,2 0,9 2,7 2,9 2,9 2,9 2,9
200 0,1 1,5 5,3 8,0 8,1 8,1 8,1
6,1 10,7 12,0 12,0 12,0
300 0 1,6
500 0 1,7 6,3 11,8 15,6 16,2 16,2
5,9 11,4 16,2 19,4 19,6
1 k -0,3 1,5
3,7 13,9 19,2 20,7
3 k -1,6 -0,1 9,2
5 k -2,3 -0,6 2,9 8,4 13,5 18,7 20,4
2,6 8,2 13,6 18,1 19,2
10 k -3,5 -1,4
15 k -6,3 -3,3 1,5 7,3 12,2 15,0 15,0
NOTES
1 The input level of 0 dB is the reference audio input level at 1 000 Hz.
2 The encode level of 0 dB is the recorded reference audio level specified in 12.1.3.
3 A block diagram for encoding is shown below.
4 The frequency response of play-back decoder shall be complementary to the record encoder.

Encoder input Encoder output
Encoder
/EC 289193
12.3 Track usage
12.3.1 Non-stereophonic audio
The primary programme audio channel shall be recorded on the audio 1 track.

961 ©IEC:1993 – 41 –
12.3.2 Stereophonic audio
When separate channels are used for stereophonic audio, the left channel shall be
recorded on the audio 1 track and the right channel on the audio 2 track. When sum and
difference channels are used for stereophonic audio, the left plus right channel shall be
recorded on the audio 1 track and the left minus right channel on the audio 2 track.
12.3.3 Program audio head phasing
When the same signal is recorded on the audio 1 and audio 2 tracks, the records shall be
so phased that when reproduced with a head wide enough to sense the recorded flux on
both tracks, the result will be additive.
12.3.4 Recording polarity
When a positvie going waveform is present on pin-2 against pin-3 of the input circular
connector, as defined in IEC XXX or EBU R-50, the audio head shall generate a magnetic
flux such that the direction of remanent flux on the tape is from north to south, with the
south pole pointing in the direction of the tape travel.
13 FM audio signal recording (channels 3 and 4)
FM audio signals can only be recorded in MODE II. Audio signals for the two channels
shall be used to individually frequency modulate two carriers. The carriers shall be located
in the low-frequency range and added to the frequency-modulated chrominance signal.
13.1 Signal processing
A signal processing system as specified by this standard shall contain the following
elements.
13.1.1 An audio noise reduction scheme incorporating compression.
13.1.2 A linear frequency modulator having constant deviation with respect to the ampli-
tude of the modulating frequencies.
A means of adding the two FM audio signals to the chrominance signal in the
13.1.3
ratio specified.
13.2 Reference levels
13.2.1 Recording and reproducing level indicator
FM audio signal recording and reproducing levels of the video tape recorder shall be
adjusted with reference to a standard volume indicator or equivalent, as specified in
IEC 268-17.
13.2.2 Recorder reference level
When a recording is made from a sinusoidal signal having a frequency of Hz with the
reference deviation, the recording volume indicator shall be adjusted to deflect to its
reference level scale mark.
961 © I EC:1993 - 43 -
13.3 Noise reduction
A noise reduction scheme will be employed with the following characteristics.
13.3.1 Compression ratio
The compression ratio shall be 2:1 in logarithmic scale for all input levels.
13.3.2 Frequency response
The frequency response of the compressor at reference input level shall be in accordance
with the following:
14 k
700 1 k 2 k 4 k 7 k 10 k
Frequency (Hz) 50 100 200 400
+4,1 +4,8 +5,3
0 +0,1 +0,3 +1,2 +2,7
Response (dB) 0 0 0
NOTE — Figure 14 represents a possible implementation.
13.3.3 Transient response
The transient response shall be as follows:
,attack time: 1,8 ms ± 0,4 ms
-
40 ms ± 8 ms
- recovery time:
15 ms ± 3 ms
- hold time:
The dynamic characteristics of the compression are shown in figure 15.
13.4 Frequency modulation
13.4.1 Carrier frequencies
The carrier frequencies shall be as shown below:

310 kHz ± 5 kHz
- left channel (CH3):
540 kHz ± 5 kHz
- right channel (CH4):
13.4.2 Frequency deviation
Reference deviation
13.4.2.1
The recording reference deviation shall be ± (25 ± 0,75) kHz at a reference frequency of
400 Hz.
13.4.2.2 Maximum deviation
The maximum deviation shall not exceed ±75 kHz.
13.5 Recording current
chrominance record-
The recording current for the two FM audio carriers relative to the
ing current specified in 11.2.8.1 shall be -24 dB ± 2 dB for channel 3, and -26 dB ± 2 dB
for channel 4.
961 ©IEC:1993 – 45 –
13.6 Track usage
13.6.1 Non-stereophonic audio
The primary programme audio channel shall be recorded on channel 3.
13.6.2 Stereophonic audio
When separate channels are used for stereophonic audio, the left channel shall be
recorded on channel 3 and the right channel on channel 4. When sum and difference
channels are used for stereophonic audio, the left plus right channel shall be recorded on
channel 3 and the left minus right channel on channel 4.
Recording polarity
13.6.3
When a positive going wave-form is present on pin-2 against pin-3 of the input circular
connector, as defined in IEC XXX or EBU R-50 the recording frequency for the FM audio
signal shall increase.
14 Time and control code recording
14.1 Designated track for time and control code
The longitudinal track identified as time and control code track shall be used for recording
of time and control code signals as specified in IEC 461.
14.2 Recording method
The recording level shall be at saturation of the magnetic domains which is defined as that
point above which a 0,5 dB increase in output level results from a 1 dB increase of input
level, as indicated on an r.m.s. reading meter.
15 Tracking control recording
15.1 Tracking control signal
15.1.1 The tracking control recording shall be a series of constant flux levels alternating
10a and
in polarity at field rate, and completing one cycle per frame, as shown in figures
10b.
15.1.2 The polarity of the tracking control recording flux shall be such that transitions
from the south poles of the magnetic domains to the north poles of the magnetic domains
occur during the vertical intervals identifying the first field, and the transitions of the north
poles of the magnetic domains to the south poles of the magnetic domains occur during
the vertical intervals identifying the second field.

– 47 –
961 ©IEC:1993
15.2 Tracking control and video timing
Recording current transitions representing video fields shall occur 1,5 lines ± 1,0 line after
the negative going transitions of the edge of the field-synchronizing pulse, as shown in
figures 10a and 10b.
15.3 Recording method
The recording level shall be at saturation of the magnetic domains which is defined as that
point above which a 0,5 dB increase in output level results from a 1 dB increase of input
level, as indicated on an r.m.s. reading meter.
SECTION FIVE: TYPE-L FORMAT VIDEO TAPE AND VIDEO TAPE CASSETTE
16 Mechanical characteristics of video tape cassette
16.1 Cassette outside dimensions
Two sizes of cassette shall be identified as follows:
Figures
Dimensions (mm)
Model
x 156 x 25 Figures 16 to 23
S (small) cassette 96
Figures 25 to 33
145 x 254 x 25
L (large) cassette
16.2 Datum planes
Datum plane Z is determined by three datum spots A, B and C, as shown in
16.2.1
figures 18a and 27a.
Datum plane X shall be perpendicular to datum plane Z and include the centres
16.2.2
of datum holes (a) and (b), as shown in figures 17 and 26.
16.2.3 Datum plane Y shall be perpendicular to both datum planes X and Z and include
the centre of datum hole (a), as shown in figures 17 and 26.
Window area and label area
16.3
The cross-hatched areas in figures 16 and 25 are defined as the label/window area and
rface.
shall not protrude beyond the height of the cassette su
16.4 Manufacturer's identification holes
Three manufacturer's holes, referred to as "recognition holes", shall be provided (refer to
figures 17 and 26). The closed status of the hole shall express state "1". The open status
of the hole shall express state "0".

961 © I EC:1993 – 49 –
16.4.1 Tape type identification hole
Hole one shall identify the tape type within the cassette. State "1" shall indicate oxide
particle tape and state "0" shall indicate metal particle tape. Detection of tape type by the
machine shall determine MODE I or MODE II operation.
16.4.2 Type thickness identification hole
Hole two shall identify tape thickness. State "1" shall identify 20 pm tape and state "0"
shall identify 15 pm tape.
16.4.3 Reel hub diameter identification hole
Hole three shall identify the reel hub diameter. State "1" shall identify a small hub and
state "0" shall identify a large hub.
For details concerning usage, refer to figures 21 and 30.
16.5 Safety tab and safety plug
16.5.1 , The use of the safety tab (for oxide tapes) and safety plug (for metal tapes) is
intended to activate or produce a record lockout condition in the event that the safety
tab/plug is activated.
16.5.2 S cassette
The S cassette may contain either oxide or metal particle tape. When loaded with oxide
tape the safety tab (for oxide), as shown in figure 17, shall activate the MODE I record
lockout condition if the safety tab is removed. A hole having a minimum depth of 10 mm
from the datum plane Z (section C-C in figure 17), defines the mechanical tolerances for
the sensing device.
When loaded with metal particle tape, the safety tab (for oxide) shall be removed, thus
preventing the record condition for machines capable of MODE I operation. The safety
plug,
...