SIST EN 61237-1:1999

SLOVENSKI STANDARD
01-april-1999
Broadcast video tape recorders - Methods of measurement -- Part 1: Mechanical
measurements (IEC 61237-1:1994)
Broadcast video tape recorders - Methods of measurement -- Part 1: Mechanical
measurements
Meßverfahren für Videobandgeräte für den Rundfunk -- Teil 1: Mechanische Messungen
Magnétoscopes de radiodiffusion - Méthodes de mesure -- Partie 1: Mesures
mécaniques
Ta slovenski standard je istoveten z: EN 61237-1:1994
ICS:
33.160.40 Video sistemi Video systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME CEI
IEC
INTERNATIONALE
1237-1
INTERNATIONAL
édition
Première
STANDARD
First edition
1994-06
Magnétoscopes de radiodiffusion -
Méthodes de mesure -
Partie 1:
Mesures mécaniques
Broadcast video tape recorders -
Methods of measurement -
Part 1:
Mechanical measurements
Copyright — all rights reserved
Droits de reproduction réservés —
© CEI 1994
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
any form or by any means, electronic or mechanical,
utilisée sous quelque forme que ce soit et par aucun pro-
cédé, électronique ou mécanique, y compris la photocopie et including photocopying and microfilm, without permission
in writing from the publisher.
les microfilms, sans raccord écrit de réditeur.
Suisse
Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé Genève,
Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission PRICE CODE P
Me»tayHapoaHaa 3neItrporexifflecnaa KOMHCCHA
I
i::
Pour prix, voir catalogue en vigueur •
For price, see current catalogue

1237-1 ©IEC:1994 – 3 –
CONTENTS
Page
FOREWORD 5
Clause
1 Scope 7
2 Normative references
3 General 9
4 Test conditions 9
5 Measuring equipment 9
5.1 Mechanical measurements 9
5.2 Optical measurements 9
6 Recorder measurements
6.1 Diameter of drum 9
6.2 Projection of video head pole tips 11
11 6.2.1 Mechanical measurement
11 6.2.2 Optical measurement
6.3 Gap width of video heads
11 6.4 Coplanarity error of video heads
7 Measurements on recorded tape
15 7.1 Tape speed and pitch of the video tracks
15 7.1.1 Tape speed v (first method)
15 7.1.2 Track pitch J (first method)
7.1.3 Tape speed and pitch of the video tracks (second method)
(VRP) 7.2 Position of the video reference point
VRP position (first method)
7.2.1 Measurement of the
17 7.2.2 Tracking and drum phase error (second method)
17 7.3 Location of records on sound and time code tracks
7.3.1 Track location to the reference tape edge
7.3.2 Longitudinal location of records
7.4 Video track geometry 19
7.4.1 Video track width I
7.4.2 Cross-tape measuring technique (first method)
7.4.3 Dynamic track measurement (second method)
Figures
Annexes
A Magnetic development of recorded tape
B Bibliography
1237-1 © I EC:1994 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
BROADCAST VIDEO TAPE RECORDERS -
METHODS OF MEASUREMENT -
Part 1: Mechanical measurements
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.
The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
2)
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.
They have the form of recommendations for international use published in the form of standards, technical
3)
reports or guides and they are accepted by the National Committees in that sense.
In order to promote international unification, IEC National Committees undertake to apply IEC International
4)
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 1237-1 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:
DIS Report on voting
60B(CO)169
60B(CO)158
Full information on the voting for the approval of this standard can be found in the report
on voting indicated in the above table.
Annex A forms an integral part of this standard.
Annex B is for information only.

1237-1 © I EC:1994 - 7 -
BROADCAST VIDEO TAPE RECORDERS -
METHODS OF MEASUREMENT -
Part 1: Mechanical measurements
1 Scope
This part of IEC 1237 describes the mechanical measurement methods on video tape
recorders relating to the compatibility parameters for recording and measuring methods of
the recorded tape.
The allowable tolerances for the rated values for acceptable performance are not given in
this standard, but may be derived from the specifications for the related system i.e.
appropriate publications, manufacturers' specifications, etc.
The necessary reference and calibration tapes are either mentioned in the specific IEC
publication of the equipment under test or included in IEC 1105.
This standard deals with special mechanical measurement techniques for broadcast VTRs.
It does not, however, cover the special mechanical measurements of the earlier transverse
track video recorder standard (IEC 347). For those measurements see IEC 1055.
The methods are applicable to acceptance tests, performance comparison and, as far as
possible, for routine checks.
2 Normative references
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this part of IEC 1237. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and pa rties to
rt of IEC 1237 are encouraged to investigate the possibility of
agreements based on this pa
applying the most recent editions of the normative documents indicated below. Members
of IEC and ISO maintain registers of currently valid International Standards.
IEC 347: 1982, Transverse track video recorders
Time and control code for video tape recorders
IEC 461: 1986,
Measurement techniques and operational adjustments of broadcast
IEC 1055-1: 1991,
VTRs - Part 1: Operational adjustments on analogue composite broadcast VTRs (Report)
IEC 1055-2: 1991, Measurement techniques and operational adjustments of broadcast
VTRs - Part 2: Special mechanical measurements and alignments (Report)
Reference tapes for video tape recorder systems
IEC 1105: 1991,
1237-1 © I EC:1994 - 9 -
3 General
To ensure that the results obtained at a specific time and at a specific place are
comparable to other measurements, it is advisable to specify the test signals, measuring
devices and types of tapes used together with the results obtained.
4 Test conditions
If not otherwise stated, all measurements shall be carried out at the following atmospheric
conditions:
- temperature 20 °C ± 1 °C;
50 % ± 2 %;
- relative humidity
- air pressure 86 kPa to 106 kPa;
24 h.
- conditioning before testing
5 Measuring equipment
5.1 Mechanical measurements
For some measurements, precision micrometers or dial indicators with 1 µm resolution are
sufficient. Instruments with electrical read-out should be preferred.
For drum geometry measurements a three-coordinate measuring device with an accuracy
below 1 µm is recommended.
5.2 Optical measurements
Measurements are made by a high power microscope equipped with an X-Y-table and a
scaled Z-axis.
For measurements in the µm area the microscope objective shall have a magnification of
50x and a numerical aperture of 0,85. The eye-piece, equipped with cross-hairs shall have
a magnification >_10x. A video camera/monitor system with electronic cross-hairs gives
better reproducible results. The X-Y-table shall have a measuring range of at least
100 mm x 50 mm. The measuring accuracy in X-, Y- and Z-axis shall be <_ 1 µm.
For data acquisition and processing a computer is recommended.
6 Recorder measurements
6.1 Diameter of drum
The drum is measured by means of a precision micrometer or a multicoordinate measuring
system. Measurements are made at several points of the drum, and these points shall be
specified by the appropriate standard or the manufacturer.

1237-1 ©IEC:1994 - 11 -
6.2 Projection of video head pole tips
6.2.1 Mechanical measurements
Measurements are made by means of a precision dial indicator. Usually either the upper
es as reference, depending on the specifications of the standard or
or the lower drum se rv
of the VTR manufacturer.
The measuring device is specified and often supplied by the VTR manufacturer.
Instructions and precautions are given in the users' manual of the measuring device.
6.2.2 Optical measurements
The scanner is mounted on the microscope table with the rotating axis parallel to one
table axis. Adjust the second table axis so that the optical axis crosses the rotating axis
ace at the reference area as specified and set the Z-axis
and lock. Focus to the drum su rf
measure to zero. Shift the table and rotate the drum till the video head gap under test is at
the image center. Focus to the head gap and read the tip projection in the Z-axis.
Gap width of video heads
6.3
(The dimension of magnetic gap parallel to the plane of the tape and perpendicular to the
direction of the relative tape to head movement)
Scanner mounting is the same as in 6.2.2.
Focus on the head gap under test and measure the head gap width.
For azimuth heads measure the projected width of the gap.
6.4 Coplanarity error of video heads
Scanner mounting is the same as in 6.2.2, rotate from head to head.
The center of the head gap width is the standard measuring point for all play heads and
guard band recording heads.
In systems with overlap recording (gap width is more than the track pitch), the gap edge of
the record or erase head which overlaps the prior recorded track is to be measured.
In systems with separate video heads for record, play and erase the video heads are
located in different planes.
If the video heads of one type (e.g. record) are not in a constant angular distance it yields
in an axial displacement. This displacement shall be considered so that all video heads of
one type are measured in one plane (e.g. record plane).

– 13 –
1237-1 ©IEC:1994
The coplanarity error is the peak-to-peak deviation in one plane.
The result is measured in micrometers, center measure or corner measure shall be stated.
7 Measurements on recorded tape
A first method is to record a tape and make the magnetic footprint on tape visible by
developing it by means of a suspension of ferro-magnetic powder. Methods for this
developing are de
...