Helical-scan video-tape cassette system using 19 mm (3/4 in) magnetic tape, known as U-format

Applies to magnetic video recording and/or playback with 19 mm (3/4 in) tape cassettes on two-head helical-scan videocassette recorders, suitable for recording and/or playback of monochrome as well as colour television programmes. Gives characteristics necessary to permit the interchangeability of cassettes.

Video-Bandkassettensystem mit Schrägspuraufzeichnung auf Magnetband 19 mm, bekannt m-als U-Format

Système à cassette à bande vidéo à balayage hélicoïdal utilisant la bande magnétique de 19 mm (3/4 in), d'appellation format-U

S'applique à l'enregistrement magnétique et/ou à la lecture de cassettes à bande de 19 mm (3/4 in) pour enregistreurs à cassette à deux têtes et à balayage hélicoïdal convenant à l'enregistrement et/ou à la lecture de programmes de télévision monochrome aussi bien que de programmes couleur. Donne des caractéristiques, dimensionnelles et autres, nécessaires pour permettre l'interchangeabilité des cassettes.

Helical-scan video-tape cassette system using 19 mm (3/4 in) magnetic tape, known as U-format (IEC 60712:1993)

General Information

Status
Published
Publication Date
31-Mar-1999
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Apr-1999
Due Date
01-Apr-1999
Completion Date
01-Apr-1999

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SLOVENSKI STANDARD
SIST EN 60712:1999
01-april-1999
Helical-scan video-tape cassette system using 19 mm (3/4 in) magnetic tape,
known as U-format (IEC 60712:1993)
Helical-scan video-tape cassette system using 19 mm (3/4 in) magnetic tape, known as
U-format
Video-Bandkassettensystem mit Schrägspuraufzeichnung auf Magnetband 19 mm,
bekannt m-als U-Format
Système à cassette à bande vidéo à balayage hélicoïdal utilisant la bande magnétique
de 19 mm (3/4 in), d'appellation format-U
Ta slovenski standard je istoveten z: EN 60712:1994
ICS:
33.160.40 Video sistemi Video systems
SIST EN 60712:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60712:1999

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SIST EN 60712:1999

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SIST EN 60712:1999

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SIST EN 60712:1999

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SIST EN 60712:1999

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SIST EN 60712:1999
NORME CEI
INTERNATIONALE I EC
712
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
1993-06
Système à cassette à bande vidéo à balayage
hélicoïdal utilisant la bande magnétique
de 19 mm (3/a in), d'appellation format-U
Helical-scan video-tape casse tte system
using 19 mm (34 in) magnetic tape,
known as U-format
CEI 1993 réservés — Copyright — all rights reserved
© Droits de reproduction
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque fourre que ce soit et par aucun pro- any form or by any means, electronic or mechanical,
including photocopying and microfilm, without permission
cédé, électronique ou mécanique, y compris la photocopie et
in writing from the publisher.
les microfilms, sans l'accord écrit de l'éditeur.
Bureau Central de la Commission Electrotechnique Inte rnationale 3, rue de Varembé Genève, Suisse
Commission Electrotechnique Internationale CODE PRIX
X
International Electrotechnical Commission
PRICE CODE
MewayHapoaHaa 3neinporexHu'ecKaa KoMHccun
IEC
Pour prix, voir catalogue en vigueur
• •
For price, see current catalogue

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SIST EN 60712:1999
712 ©IEC:1993 – 3 –
CONTENTS
Page
FOREWORD 9
INTRODUCTION 11
Clause
CHAPTER 1: SPECIFICATIONS FOR BASIC SYSTEM
SECTION 1: GENERAL
1 Scope and object 13
2 Normative references 13
3 Environment 13
3.1 Testing environment 13
3.2 Operation environment 15
SECTION 2: VIDEO-TAPE CASSETTE
4 Mechanical parameters 15
4.1 Dimensions of cassette 15
4.2 Tape path and guidance 15
4.3 Tape winding 15
4.4
Label and window area 15
4.5
Withdrawal force 15
4.6 Guiding groove 15
4.7
Safety cap and safety hole 15
4.8 Automatic stop 17
4.9 Cassette support areas 17.
4.10 Reels 17
SECTION 3: VIDEOCASSETTE RECORDERS
5 Mechanical parameters 17
5.1 Type of videocassette recorder 17
5.2 Reel spindle of videocassette recorder
17
5.3 Back tension 17
5.4 Audio and control head position 19
5.5 Audio and control head dimensions 19
5.6 Audio and control-track head position 19
5.7 Time-code head position 19
5.8
Tolerances on audio and control heads and time-code head
(U-matic H-format) 19
5.9 Gap azimuth 21
6 Tape speed 21

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SIST EN 60712:1999
712 ©IEC:1993 – 5 –
Clause Page
7 Track configuration and dimensions 21
7.1 Video track width (U-matic H-format) 23
7.2 Video guard-band width 23
7.3 Location of address track 23
7.4 Switching position between two video heads 23
8 Recording characteristics 23
SECTION 4: TAPE CHARACTERISTICS
9 Type of magnetic tape 25
10 Construction and dimensions of the tape 25
10.1 Magnetic tape thickness 25
10.2 Magnetic tape width 25
10.3 Leader tape and trailer tape thickness 25
10.4 Leader tape and trailer tape length 25
10.5 Splicing 25
11 Magnetic tape properties 27
11.1 Magnetic orientation 27
11.2 Coercivity 27
SECTION 5: RECORDING CHARACTERISTICS
12 Luminance channel 27
12.1 Modulation system 27
12.2 Recording current 27
12.3 Characteristic frequencies 29
12.4 Pre-emphasis 31
12.5 Recording frequency bandwidth 33
12.6 White clipping level 33
13 Audio signal channels 33
13.1 Audio recording characteristic 33
13.2 Optimum audio bias current 33
13.3 Use of the audio tracks 35
13.4 Recorded tape flux characteristics 35
14 Control signal channel 35
14.1 Control signal polarity 35
14.2 Waveform of recording current 37
14.3 Control signal level 37
14.4 Time-code recording 37
T1 2 14.5 Duty cycle /T 37
15 Chrominance channel 37
15.1 Modulation system 39
15.2 Chrominance signal bandwidth 39
15.3 Recording signal spectrum 39

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SIST EN 60712:1999
712 ©I EC:1993 – 7 —

Clause
Page
16 U-matic H-format
chrominance channel 41
16.1 Modulation system 41
16.2 Reference frequencies 41
16.3 Chrominance
pre-emphasis 43
16.4 Chrominance
recording current 43
16.5 Chrominance
signal bandwidth 43
16.6 Time delay 43
FIGURES 45
CHAPTER 2: SPECIFICATIONS FOR STANDARD ALIGNMENT TAPE
SECTION 6: GENERAL
17 Scope and object 77
18 Environment 77
SECTION 7: RECORDED TAPE CHARACTERISTICS
19 Construction of tape and cassette 77
20 Type of tape 77
21 Tape dimensions 77
21.1 Tape thickness 77
21.2 Tape width 77
22 Magnetic orientation 79
23 Track configuration and dimensions 79
SECTION 8: VIDEO-TAPE RECORDER
24 Type of video-tape recorder 79
SECTION 9: RECORDING CHARACTERISTICS
25 Recording characteristics 81
26 Recording of luminance signal 81
26.1 Characteristic frequencies 81
26.2 Pre-emphasis 81
27 Recording current of chrominance signal 81
SECTION 10: RECORDED SIGNALS
28 Video signal 83
29 Audio signal 83

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SIST EN 60712:1999
712 ©IEC:1993 – 9 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
HELICAL-SCAN VIDEO-TAPE CASSETTE SYSTEM
USING 19 mm ( 3
A in) MAGNETIC TAPE
KNOWN AS U-FORMAT
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.
International Standard IBC 712 has been prepared by sub-committee 60B: Video record-
ing, of IEC technical committee 60: Recording.
This second edition cancels and replaces the first edition published in 1982 of which it
constitutes a minor revision. It includes specifications for U-matic H-format magnetic tape.
The text of this standard is based on the following documents:
DIS
Report on Voting
60B(CO)109 60B(CO)120
Full information on the voting for the approval of this standard can be found in the report
on voting indicated in the above table.

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SIST EN 60712:1999
712 ©IEC:1993 -11 -
INTRODUCTION
This International Standard provides specifications for a helical-scan video-tape cassette
recording and reproducing system which makes use of tape 19 mm (
34 in) wide. The
system is widely used in educational and industrial television facilities and is suitable for
both 625 line-50 field and 525 line-60 field television signals. The parameters for different
systems are given in the specifications which follow. This cassette system is also used in
some broadcasting facilities in conjunction with special equipment designed to stabilize
the reproduced signals to meet broadcasting requirements.
The mechanical and electrical specifications for the U-matic H-format are contained in this
standard.

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SIST EN 60712:1999
712 ©IEC:1993 —13 —
HELICAL-SCAN VIDEO-TAPE CASSETTE SYSTEM
USING 19 mm ( 3A in)
MAGNETIC TAPE
KNOWN AS U-FORMAT
CHAPTER 1:
SPECIFICATIONS FOR BASIC SYSTEM
SECTION 1: GENERAL
1 Scope and object
This standard applies to magnetic video recording and/or playback with 19 mm (3/4 in) tape
cassettes on two-head helical-scan videocassette recorders, suitable for recording and/or
playback of monochrome as well as colour television programmes.
It gives dimensional and other characteristics necessary to permit the interchangeability of
cassettes. For some parameters, the specification is only possible through the description
of recorded tapes which implies making reference to the television system or standard in
use. In such cases, the reference made for instance to 525 line-60 field or 625 line-50 field
systems shall be considered as an example.
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:
Magnetic tape sound recording and reproducing systems
IEC 461: 1986,
Time and control code for video-tape recorders
3 Environment
3.1 Testing environment
Tests and measurements made on the system to check the requirements of this standard
shall be carried out under the following conditions:
temperature: 20 ± 1 °C;
relative humidity: 48 % to 52 %;
air pressure: 86 kPa to 106 kPa;
conditioning before testing: 24 h.

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SIST EN 60712:1999
712 ©IEC:1993 –15 –
3.2 Operation environment
The system shall operate under the following conditions:
temperature (in recorder):
15 °C to 50 °C;
relative humidity: 45%to75%.
SECTION 2: VIDEO-TAPE CASSETTE
4 Mechanical parameters
4.1
Dimensions of cassette
The dimensions necessary to permit interchangeability of cassettes shall be in accordance
with figures 1 to 5 and 1 a to 5a and table 1.
4.2 Tape path and guidance
The tape path and guidance are given in figure 6.
4.3 Tape winding
The magnetic coating on the tape shall face out of the cassette. The direction of tape
travel is from left to right when the coated side is facing the observer, i.e., from supply reel
and outside on the take-up reel (see figure 6).
4.4 Label and window area
The level and window area shall be in accordance with the dimensions given in figures 1
and la. The label as well as the window shall not protrude beyond the su rf
ace of plane A
in figures 1 and 1 a.
4.5 Withdrawal force
The leader tape and trailer tape which are spliced to each end of the magnetic tape shall
be so attached to the reels that they can withstand a withdrawal force of 20 N.
4.6 Guiding groove
The cassette shall be provided with a guiding groove for correct insertion into the
record/playback equipment as shown in figures 1 and la.
4.7 Safety cap and safety hole
The safety hole to prevent accidental erasure is shown in figures 2 and 2a. Recording
shall be possible only when the hole is covered by the safety cap as shown in the figures.

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SIST EN 60712:1999
712©IEC:1993 - 17 -
4.8 Automatic stop
The optical transmittance of the leader and the trailer tape shall be at least 30 % to ensure
that the automatic stopping device of the machine functions properly at both ends of the
magnetic tape.
4.9 Cassette support areas
The cassette shall be supported by the record/playback equipment only on the four datum
points at the locations shown in figures 5 and 5a. (The suppo rt
s are on the record/
playback machine.)
4.10
Reels
4.10.1 Arrangement of reels
The supply reel shall be placed in the shell with its larger flange side down and the
tape-up reel is laced with its larger flange side up.
4.10.2
Dimensions of reels
The dimensions of the reels shall be shown in figures 3 and 3a. Choice of hub diameter is
as shown below.
Type I Type II Type I Type Il
(playing time (playing time (playing time (playing time
60 min) 30 min)
20 min) 10 min)
Flange diameter
mm 121
121 87 87
Hub diameter
(supply reel)
38 80 38 80
mm
SECTION 3: VIDEOCASSETTE RECORDERS
5 Mechanical parameters
5.1 Type of videocassette recorder
The videocassette recorder shall be of the helical-scan type with two video heads.
5.2 Reel spindle of videocassette recorder
Dimensions and other characteristics are given in figures 4 and 4a and table 1.
5.3 Back tension
Back tension at the maximum amount of tape on the supply reel shall be between 0,60 N
and 0,80 N at the entrance of the drum as indicated in figure 6. The range of tension
between the maximum and minimum amount of winding shall be set as follows:

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SIST EN 60712:1999
712 ©IEC:1993 - 19 -
tension at minimum amount of winding (38 0)
- 1,3
tension at maximum amount of winding (118 0)
5.4
Audio and control head position
The distance on the tape pattern from the end of the 180° scan of video head
(S0) to the
audio and control head position is 74,0 ± 0,5 mm, dimension (X) as shown in figure 8.
5.5 Audio and control head dimensions
Audio and control head dimensions and tolerances shall be in accordance with figure 7.
5.6 Audio and control-track head position
The distance (X) on the tape pattern between the end of the 180° scan of the video head
(S0) and the audio and control head position, is 74,0 ± 0,2 mm.
5.7 Time-code head position
For practical reasons, it was not possible in the past to specify a single figure for the
distance (Y) on the tape from the beginning (S 1) of the 180° scan of video head to
the address head position. The distance was:
for studio machines: 93,0 ± 2,5 mm
for portable machines: 45,5 ± 2,0 mm.
This difference in distance represents a time difference of 0,5 s which may have to be
taken into account or corrected when tapes are interchanged between portable and studio-
machines.
However, the figure of 45,5 ± 2,0 mm is now to be preferred.
5.8 Tolerances on audio and control heads and time-code head (U-matic H-format)
The audio, control and time-code head tolerances shall be in accordance with the follow-
ing illustration:

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SIST EN 60712:1999
712 © IEC:1993 —21 —
u)
0
Time code Audio and
ô
ô
head control heads
+1
^
N
^
0
0
■.i.■ •i.•uI1
Control
track
^
0
ô
^
-H
0
^
ô
ô
+i
I ^
ô
__ Address track=
a-1
*
N
Audio track '4%%
_
v
co ii%ii^%/, Audio track
///- %l%ii:% ï^
Tape length on the drum
J _ ►^^
Y
(180° scan of video head)
!EC 555193
NOTE — Audio and control gaps shall be in line.
5.9 Gap azimuth
5.9.1 Recording of longitudinal tracks
The azimuth of all head gaps used for the recording of longitudinal tracks shall be perpen-
dicular to the direction of tape motion.
5.9.2 Recording of video tracks
The azimuth of the video head gaps shall be perpendicular to the direction of head motion.
6 Tape speed
The tape speed shall be 95,3 ± 0,2 mm/s.
7 Track configuration and dimensions
The track configuration and dimensions shall be in accordance with figure 8, and table 2.
The switching position between the two video heads shall lie between five and eight
horizontal scanning lines ahead of the front edge of the vertical synchronizing pulse.
The minimum overlap of the two video heads shall be three horizontal lines on either side
of the nominal position, as shown in figure 9.

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SIST EN 60712:1999
712 © IEC:1993 - 23 -
This recording format permits an optional address track, intended for special uses such as
editing and cueing. Track dimensions are identified as N and T in table 2. Longitudinal
dimensions and electrical recording characteristics under study. The recording head for
this track will be located between the main erase head and the video scanner.
7.1 Video track width (U-matic H-format)
Video track width (M) shall be 0,125 ± 0,007 mm.
7.2 Video guard-band width (U-matic H-format)
Video guard-band width (S) shall be 0,040 mm.
7.3 Location of address track (U-matic H-format)
Tape edge to upper limit address track (N) shall be 3,4 ± 0,1 mm.
7.4 Switching position between two video heads (U-matic H-format)
The switching position between the two video heads shall lie between 0,5 and 3 horizontal
scanning lines ahead of the front edge of the field synchronizing pulse.
The minimum overlap of the two video heads shall be 3 horizontal lines on either side of
centre, as shown below:
Reproduced field signal
RF signal
3 lines 3 lines
.-
Minimum overlap
IEC 556/93
8 Recording characteristics
The recording characteristics of videocassette recorders shall be in accordance with the
requirements specified in Section 5.

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SIST EN 60712:1999
712 ©IEC:1993 - 25 -
SECTION 4: TAPE CHARACTERISTICS
9 Type of magnetic tape
A high-resolution magnetic tape (e.g. Cr0 ) should be used. See 11.2.
2
10 Construction and dimensions of the tape
10.1 Magnetic tape thickness
The maximum allowable thickness of the magnetic tape, including the coating shall be
27,0 gm.
NOTE – Tape having total thickness between 27,0 µm to 28,5 p.m may also be used for cassettes with a
playing time substantially less than 60 min.
10.2 Magnetic tape width
The width of the magnetic tape shall be 19,00 ± 0,03 mm.
10.3 Leader tape and trailer tape thickness
The maximum allowable thickness of the leader tape and trailer tape shall be 45 gm.
10.4 Leader tape and trailer tape length
The length of the leader tape and trailer tape shall be 0,95 ± 0,10 m.
10.5 Splicing
The leader tape and trailer tape shall be spliced as illustrated below.
II
I
/ I
Leader Trailer
Magnetic
tape tape tape
F
^
Coated su rface
L J
/EC 557193
NOTE – The leader tape must be free of electrostatic charge. If tape is treated for this purpose, then
treated side should face same side as magnetically coated surface.

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SIST EN 60712:1999
712 ©IEC:1993 — 27 —
10.6 The splice gap between the leader tape and the magnetic tape shall be below
0,2 mm.
11 Magnetic tape properties
11.1
Magnetic orientation
The magnetic coating shall be longitudinally oriented.
11.2 Coercivity
The coercivity shall be approximately 40 x 103 A/m to 48 x 10 3 A/m (approximately
500 Oe to 600 0e).
SECTION 5: RECORDING CHARACTERISTICS
12 Luminance channel
1 2 3
F
397/YI
A = low-pass filter
NOTE — The characteristics of the low-pass filter are important in determining the performance of the
luminance channel. At this time, specifications for this filter cannot be standardized since different designs
are used by various manufacturers.
B = pre-emphasis (see 12.4)
C = FM modulator
D = FM high-pass filter (see 12.2.2)
E = recording amplifier
F = video head
1 = input signal: composite video signal (monochrome) or composite colour signal
2 = FM luminance signal
3 = recording current
12.1 Modulation system
The video information shall be recorded in the form of an RF signal frequency modulated
by the video signal. The instantaneous frequencies of the RF signal shall vary linearly with
respect to the amplitude of the modulating signal.
12.2 Recording current
12.2.1 The recording current shall have the optimum value over the entire FM carrier
bandwidth.
For U-matic H-format the recording current shall be the optimum record current at 5,3 MHz
over the entire FM carrier bandwidth.
NOTE — "Optimum record current" is the recording current value which is necessary to obtain the maximum
output signal level during playback.

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SIST EN 60712:1999
712 ©IEC:1993 -
29 -
12.2.2 The amplitude/frequency response of the FM high-pass filter shall be in
accordance with the figure below.
Response
More than
More than 15 dB
20 dB
(6 dB')
Applies to H-format
0
3 MHz
( 1 ,5* ) (4,8")
IEC 558/93
12.2.3 Low-pass filtering (U-matic H-format)
For the colour mode, the specifications of low-pass filter A are:
- attenuation at fc:
>26 dB
- attenuation between fc ± 0,5 MHz:
>15 dB
NOTE — In PAL, fc = chrominance sub-carrier frequency; in
SECAM, fo = Yon + fOe).
1/2
12.3
Characteristic frequencies
The instantaneous frequency corresponding to characteristic levels of the video signal is
given below.

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SIST EN 60712:1999
712 © IEC:1993 -31 -
Converted carrier chrominance signal
Monochrome — FM signal bandwidth
T
Colour — FM signal bandwidth
h- Frequency deviation
fl . f2
399/81

f1 = sync tip frequency 3,8 ± 0,1 MHz

f2 = peak white frequency: 5,4 ± 0,1 MHz

frequency deviation: 1,6±0,1 MHz
12.3.1 Characteristic frequencies for U-matic H-format are given below.
f= 1 sync tip frequency:
4,8 (nom.) MHz
f2 = peak white frequency: 6,4 ± 0,1 MHz
frequency deviation: 1,6 ± 0,1 MHz
12.4 Pre-emphasis
The characteristics of the video pre-emphasis network are as follows:
o
In
Out
Rb
O
O
IEC 559/93
TE = C•R =
0,60 ±0,05µs
XE = Rb/Ra = 2,5 ± 0,1

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SIST EN 60712:1999
712 ©IEC:1993 – 33 –
12.4.1 For H-format the following values apply:
TE =C Rb=
0,80±0,05}is
XE = Rb/Ra = 4,0 ± 0,3
12.5 Recording frequency bandwidth
The maximum recorded frequency of the luminance signal is:

for composite video signal (monochrome):
4,2 MHz;

for composite colour signal:
3,5 MHz.
12.5.1
Recording frequency bandwidth (H-format)
The bandwidth of the recorded luminance signal is:
for composite video signal (monochrome): 4,2 MHz (-3 dB)
for composite colour signal: 3,0 MHz (-3 dB)
12.6 White clipping level
When the sync tip level is 0 % and the white peak level is 100 %, the white clipping level
of the video signal shall lie between 135 % and 150 %.
12.6.1
White clipping level after the pre-emphasis
When the sync tip level is 0 % and the white peak level is 100 %, the white clipping level
of the video signal shall lie between 210 % and 230 %.
13 Audio signal channels
Whenever a monophonic audio signal is recorded, it shall be recorded using either
channel-2 (right) only, or both audio channels simultaneously.
In audio dubbing, channel-1 (left) is recorded.
13.1 Audio recording characteristic
(See also IEC 94: Magnetic tape sound recording and reproducing systems.)
The time constants shall be:
t1 =50µs t2 =
3180µs
13.2 Optimum audio bias current
With a sine-wave signal of 1 kHz being recorded and played back, the signal output will
rise, reach a maximum, and then decrease, as the bias is increased. Bias current shall be
set at the point where the signal output has gone beyond maximum and come down to a
level 0,5 dB below maximum.

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SIST EN 60712:1999
712©IEC:1993 – 35 –
13.3
Use of the audio tracks
13.3.1 Monophonic programme sound signals shall be recorded on audio track 2.
13.3.2 Audio track 1 may carry auxiliary sound at the user's discretion.
13.3.3 In the case of stereophonic recording, audio track 1 shall carry the left channel
and audio track 2 the right channel.
13.4 Recorded tape flux characteristics
The recorded reference audio level shall correspond to a magnetic short-circuit flux level
of 100 ± 10 nWb/m r.m.s. at 1 000 Hz, if no pre-distortion is used. The programme peaks
will normally be 9 dB above the reference level.
14 Control signal channel
The repetition frequency (see table below) of the control signal on the control track is half
the field frequency.
525 line-60 field 625 line-50 field
30 Hz
Repetition frequency
or 25 Hz
29,97 Hz
Vertical sync signal
FIE
Recording current
(saturation level)
Reproducing signal
Polarity: plus, north
IEC 560l93
NOTE – Direct current shall be applied to the terminal of the head so as to make the head gap on the
take-up reel side north polarity. In this case, the terminal to which plus voltage is applied is defined as
the plus terminal. The positive going control pulse is applied to the plus terminal.
14.1 Control signal polarity
A positive going pulse signal shall be obtained at the plus terminal when there is a change
from south to north in the polarity of the magnetic tape at reproduction. The reference
pulse shall be the positive going pulse.

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SIST EN 60712:1999
712 ©IEC:1993 - 37 -
14.2 Waveform of recording current
The rise time of recording current shall be less than 200 µs.
NOTE – The waveform of the recording current need not be a square-wave, if interchangeability of
recorded tapes can be maintained. (In the case of a rectangular wave, the duty cycle T 1 /T2 must be more
than 50 %.)
14.3 Control signal level
With control signal recorded at saturation level by a recorder/player and played back by
the same machine, the operation shall be normal even at a signal level 6 dB below normal
level.
14.4
Time-code recording
The time-code is defined in IEC 461.
14.4.1 Time-code track
When time-code is recorded, it shall be placed on the address track and recorded without
a.c. bias.
14.4.2 Time-code recording level
The address track recording current shall be that at which the playback signal level is 2 dB
to 3 dB below the saturation level, to suppress interaction with the signals on the video
tracks.
14.5 Duty cycle T1/T2
The width of the pulse of north polarity, T 1 , shall be such that 0,5 T2 <– T1 <_ 0,8 T2.
15 Chrominance channel
5

2 6
4
G
H F
402/X1
G = bandpass filter
H = mixer
I = low-pass filter
F = video head
1 = input signal: composite colour signal
2 = band limited chrominance signal
3 = mixing frequency
4 = NTSC: Chrominance signal having a converted carrier frequency of fc = 688,374 ± 0,200 kHz
which is obtained by multiplying the horizontal line-frequency by 43,75 (= 175/4)
PAL: Chrominance signal having a converted carrier frequency of f = 685,547 ± 0,200 kHz,
which is obtained by multiplying the horizontal Tine-frequency %y 43,875 (= 351/8)

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SIST EN 60712:1999
712 ©IEC:1993 - 39 -
SECAM: Chrominance signal with converted carrier.
Unmodulated carrier red line: 712,915 ± 0,200 kHz
VA),
unmodulated carrier blue line: 869,165 ± 0,200 kHz (1B)
5 = band-limited FM luminance signal
The time difference between the luminance signal and chrominance
signal recorded on tape shall not
exceed ± 0,1 µs.
6 = NTSC and PAL: Peak-to-peak
chrominance recording current during burst* is equal to the peak-to-
peak luminance FM recording current at a frequency of 3,8 MHz, minus 20 ± 2 dB.
SECAM: Peak-to-peak
chrominance recording current during unmodulated carrier red-line
signal is equal to the peak-to-peak luminance FM recording current at a frequency of
3,8 MHz, minus 22 ± 2 dB.
NOTE – The characteristics of filters G and I are not specified separately but are included in the specifi-
cation in 15.2.
The chrominance
network characteristic for the SECAM system is as follows:
Ra
In Out
Rb
o o
1EC 561/93
Tc = C• (Ra + Rb) = 0,80±0,06 µs
X c = Rb/(Ra + R) b = 0,50 ± 0,03
This network shall be inserted just before the video head in the chrominance channel.
15.1 Modulation system
The chrominance information shall be directly recorded after conversion to the lower
frequency band.
15.2 Chrominance signal bandwidth
The chrominance signal recording bandwidth is fc ± 500 kHz, at the -3 dB points.
[fc = (fR + fB) / 2
(SECAM)]
15.3 Recording signal spectrum
The positioning of the upper and lower sidebands of the
chrominance signal with
converted carrier shall be reversed in relation to the original signal.
For burst amplitude specification, see Item 2.15 of Table II of CCIR Report 624.

---------------------- Page: 26 ----------------------

SIST EN 60712:1999
712 ©IEC:1993 – 41 –
16 U-matic H-format
chrominance channel
5
7 8
G H
J F
6
/EC 562193
G – Bandpass filter
H – Mixer
I – Low-pass filter and pre-emphasis circuits
J – Recording amplifier
F – Video head
1 – Input signal: composite colour signal according to the CCIR PAL or SECAM systems
3 – Luminance recording current
4 – Band limited chrominance signal
5 – Pilot burst (PAL only)
6 – Mixing frequency
7 – Chrominance signal with converted sub-carrier frequency
8 – Band limited
chrominance signal
9 – Chrominance recording current
16.1 Modulation sys
...

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