IEC 62122:2002
(Main)Methods of measurement for consumer-use digital VTRs - Electronic and mechanical performances
Methods of measurement for consumer-use digital VTRs - Electronic and mechanical performances
Specifies the basic methods of measurement for evaluating the electronic and mechanical performance of consumer-use digital VTRs. Enables checks of the interchangeability and characteristics of the equipment under test and enables evaluation of the quality of image and sound.
General Information
Standards Content (Sample)
INTERNATIONAL IEC
STANDARD
First edition
2002-03
Methods of measurement for
consumer-use digital VTRs –
Electronic and mechanical performances
Méthodes de mesure pour les magnétoscopes
numériques destinés au grand public –
Performances électroniques et mécaniques
Reference number
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the
60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
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edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the
base publication incorporating amendment 1 and the base publication incorporating
amendments 1 and 2.
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INTERNATIONAL IEC
STANDARD
First edition
2002-03
Methods of measurement for
consumer-use digital VTRs –
Electronic and mechanical performances
Méthodes de mesure pour les magnétoscopes
numériques destinés au grand public –
Performances électroniques et mécaniques
IEC 2002 Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale
X
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue
– 2 – 62122 IEC:2002(E)
CONTENTS
FOREWORD.7
1 Scope and object .8
2 Normative references.8
3 Terms and definitions .9
4 Measuring conditions .10
4.1 General .10
4.2 Environmental conditions .10
4.3 Power supply.10
4.4 Test signal.10
4.4.1 Video test signal .10
4.4.2 Colour bar signal .11
4.4.3 Video input signal for measuring audio characteristics.11
4.5 Measuring instruments.11
4.5.1 Noise meter .11
4.5.2 Audio signal generator .11
4.5.3 Audio level meter .11
4.5.4 Audio mixed frequency oscillator .12
4.5.5 Audio harmonic distortion meter.12
4.6 Video test tape .12
5 Methods of measurement for mechanical characteristics .12
5.1 General .12
5.2 Tape speed .12
5.2.1 Test signal.12
5.2.2 Measurement.12
5.2.3 Presentation of the results .13
5.3 Flatness of the RF envelope .13
5.3.1 Test signal.13
5.3.2 Block diagram.13
5.3.3 Measurement.13
5.3.4 Presentation of the result .14
5.4 Linearity .14
5.4.1 Test signal.14
5.4.2 Measurement.14
5.4.3 Presentation of the results .15
5.5 Effective area starting position.15
5.5.1 Test signal.15
5.5.2 Measurement.15
5.5.3 Presentation of the results .15
5.6 Track displacement measurement by image processing .15
5.6.1 Measurement system .15
5.6.2 Image processing technique.15
5.6.3 Measuring results .16
62122 IEC:2002(E) – 3 –
6 Video characteristics (analogue input/output) .17
6.1 General .17
6.2 Luminance amplitude frequency response.17
6.2.1 Test signal.17
6.2.2 Block diagram.17
6.2.3 Measurement.17
6.2.4 Presentation of results .18
6.3 Chrominance amplitude frequency response .18
6.3.1 Test signal.18
6.3.2 Block diagram.18
6.3.3 Measurement.18
6.3.4 Presentation of results .18
6.4 Luminance diagonal resolution.19
6.5 Luminance frequency characteristics of diagonal resolution (i) .19
6.6 Luminance frequency characteristics of diagonal resolution (ii).19
6.7 Luminance non-linear distortion .19
6.8 Luminance waveform distortion (linear distortion).19
6.9 Chrominance waveform distortion .19
6.9.1 Test signal.19
6.9.2 Block diagram.19
6.9.3 Measurement.19
6.9.4 Presentation of results .20
6.10 Luminance vertical waveform distortion.20
6.11 Chrominance vertical waveform distortion .20
6.12 Automatic Gain Control (AGC) operation.20
6.13 Chrominance to luminance horizontal displacement .20
6.14 Chrominance to luminance vertical displacement .20
6.15 Luminance signal-to-noise ratio .20
6.15.1 General .20
6.15.2 Test signal.21
6.15.3 Block diagram.21
6.15.4 Measurement.21
6.15.5 Presentation of the results .22
6.16 Chrominance signal-to-noise ratio.22
6.16.1 General .22
6.16.2 Test signal.22
6.16.3 Block diagram.22
6.16.4 Measurement.23
6.16.5 Presentation of the results .23
7 Composite signal decoding characteristics (luminance and chrominance separation).24
7.1 Luminance signal separation (general).24
7.2 Luminance signal separation at colour change points .24
7.3 Chrominance signal separation .24
7.4 Chrominance signal separation with three dimensional processing .24
7.4.1 Test signal.24
7.4.2 Block diagram.24
7.4.3 Measurement.24
7.4.4 Presentation of results .25
– 4 – 62122 IEC:2002(E)
7.5 Luminance signal separation with three dimensional signal processing.25
7.5.1 Test signal.25
7.5.2 Block diagram.25
7.5.3 Measurement.25
7.5.4 Presentation of results .25
8 Audio characteristics (analogue input/output) .25
8.1 General .25
8.2 Audio operational output voltage (with AGC) .26
8.2.1 Test signal.26
8.2.2 Block diagram.26
8.2.3 Measurement.26
8.2.4 Presentation of results .26
8.3 Audio operational input voltage (without AGC).26
8.3.1 Test signal.26
8.3.2 Block diagram.26
8.3.3 Measurement.26
8.3.4 Presentation of results .26
8.4 Audio maximum output voltage .26
8.4.1 Test signal.26
8.4.2 Block diagram.27
8.4.3 Measurement.27
8.4.4 Presentation of results .27
8.5 Amplitude frequency response .27
8.5.1 Test signal.27
8.5.2 Measurement.27
8.6 Phase difference between channels .27
8.6.1 Test signal.27
8.6.2 Measurement.27
8.6.3 Presentation of results .27
8.7 Signal-to-noise ratio.27
8.8 Dynamic range .27
8.8.1 Test signal.27
8.8.2 Measurement.28
8.8.3 Presentation of results .28
8.9 Harmonic distortion.28
8.10 Inter-modulation distortion .28
8.10.1 Test signal.28
8.10.2 Measurement.28
8.10.3 Presentation of result.28
8.11 Channel separation.28
8.11.1 Test signals .28
8.11.2 Measurement.28
8.11.3 Presentation of results .28
8.12 Wow-flutter.29
8.13 Pitch difference between record and playback.29
8.13.1 Test signal.29
8.13.2 Measurement.29
8.13.3 Presentation of results .29
9 Classification of the characteristics to be specified.29
62122 IEC:2002(E) – 5 –
Annex A (informative) Error rate .44
A.1 Definition .44
A.2 Block diagram .44
A.3 Measurement.44
A.4 Presentation of the results.45
A.5 Example 1.45
A.6 Example 2.45
Bibliography .47
Figure 1 – Basic block diagram of measurement system.30
Figure 2 – Measuring method for track interval .30
Figure 3 – Measuring block diagram for RF envelope flatness.31
Figure 4 – Measuring method for RF envelope flatness.31
Figure 5 – Cross-tape track height for DV format .31
Figure 6 – Cross-tape track height for D-VHS format .32
Figure 7 – Measuring method for linearity.32
Figure 8 – Measuring method for the starting position.32
Figure 9 – Block diagram of the measurement system .33
Figure 10 – Schematic diagram of the image processing technique.34
Figure 11 – Illustration of track displacement distribution (model) .35
Figure 12 – Example of calculation results.35
Figure 13 – Test signal for luminance amplitude frequency response .36
Figure 14 – Measuring block diagram for composite video signal .36
Figure 15 – Measuring block diagram for S video signal.36
Figure 16 – Test signal for chrominance amplitude frequency response .37
Figure 17 – Test signal for luminance non-linear distortion.37
Figure 18 – Test signal for luminance waveform distortion .37
Figure 19 – Test signal for chrominance waveform distortion .38
Figure 20 – Measuring method for chrominance waveform distortion .38
Figure 21 – Composite video test signal for luminance signal-to-noise ratio .39
Figure 22 – S luminance test signal for luminance signal-to-noise ratio .39
Figure 23 – S chrominance test signal for luminance signal-to-noise ratio .39
Figure 24 – Block diagram for composite video input .39
Figure 25 – Block diagram for S video input.40
Figure 26 – Composite video test signal for chrominance signal-to-noise ratio .40
Figure 27 – S luminance test signal for chrominance signal-to-noise ratio .40
Figure 28 – S chrominance test signal for chrominance signal-to-noise ratio .41
Figure 29 – Test signal for 3D chrominance signal separation.41
Figure 30 – Measuring block diagram for chrominance signal separation .41
Figure 31 – Measuring method for 3D chrominance signal separation .42
Figure 32 – Test signal for 3D luminance signal separation.42
Figure 33 – Measuring block diagram for luminance signal separation .42
– 6 – 62122 IEC:2002(E)
Figure 34 – Measuring method for 3D luminance signal separation .43
Figure 35 – Block diagram for audio characteristics .43
Figure A 1 – Structure of Data-synchronisation blocks .46
Figure A 2 – Structure of DV format data-synchronisation blocks .46
Figure A 3 – Structure of D-VHS format data-synchronisation blocks .46
Table 1 – Setting of the colour noise meter for luminance measurement .21
Table 2 – Example: white level of test signal (8 bit system) .22
Table 3 – Setting of the colour noise meter for chrominance measurement .23
Table 4– Example: Chrominance level of test signal (8 bit system) .23
Table 5 – Classification of the characteristics to be specified .29
62122 IEC:2002(E) – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
METHODS OF MEASUREMENT FOR CONSUMER-USE DIGITAL VTRs –
ELECTRONIC AND MECHANICAL PERFORMANCES
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 co-operation 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 express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, 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.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62122 has been prepared by TA 7: Moderate data rate storage
media and equipment, of IEC technical committee 100: Audio, video and multimedia systems
and equipment.
The text of this standard is based on the following documents:
FDIS Report on voting
100/452/FDIS 100/480/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
Annex A is for information only.
The committee has decided that the contents of this publication will remain unchanged until 2007.
At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 8 – 62122 IEC:2002(E)
METHODS OF MEASUREMENT FOR CONSUMER-USE DIGITAL VTRs –
ELECTRONIC AND MECHANICAL PERFORMANCES
1 Scope and object
This standard specifies the basic methods of measurement for evaluating the electronic and
mechanical performances of consumer-use digital VTRs.
The formats of open reel VTRs, Beta, VHS, and 8 mm VTRs have been standardized. Methods of
measurement for these analogue VTRs have been standardized in IEC 61041-1, IEC 61041-2,
IEC 61041-3, IEC 61041-4, IEC 61041-5, and IEC 61146-3. Digital VTR 6,35 mm DV format
and 12,65 mm D-VHS format have now been brought on the market. The methods of
measurement for these consumer-use digital VTRs should be specified and standardized.
With these measurement techniques, some items for the evaluation of performances specific
to digital VTRs have also been included.
There are two objectives for the proposed methods of measurement. One is to check the
interchangeability and characteristics of the equipment under test which are indispensable to
manufacturers, and the other is to evaluate the quality of image and sound, which concerns
the customer. The latter is a priority for consumer satisfaction.
Since a consumer can use only general-purpose instruments, any test which needs dismantling
of apparatus and requires special instruments is in principle not specified. As error rate is
important for digital equipment, an example of a method for measuring error rate is given in
annex A.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60094-3:1979, Magnetic tape sound recording and reproducing systems – Part 3: Methods
of measuring the characteristics of recording and reproducing equipment for sound on
magnetic tape
IEC 60386:1972, Method of measurement of speed fluctuations in sound recording and
reproducing equipment
IEC 60883:1987, Measuring method for chrominance signal-to-random noise ratio for video
tape recorders
IEC 61041-1:1990, Non-broadcast video tape recorders – Methods of measurement – Part 1:
General, video (NTSC/PAL) and audio (longitudinal) characteristics
IEC 61041-5:1997, Non-broadcast video tape recorders – Methods of measurement – Part 5:
High-band video tape recorders including those equipped with Y/C video connectors
(NTSC/PAL)
IEC 61834 (all parts), Recording – Helical-scan digital video cassette recording system using
6,35 mm magnetic tape for consumer use (525-60, 625-50, 1125-60 and 1250-50 systems)
ITU-R BT.471-1:1986, Nomenclature and description of colour bar signals
ITU-R BT.500-10:2000, Methodology for the subjective assessment of the quality of television
pictures
ITU-R BT.1204:1995, Measuring methods for digital video equipment with analogue input/output
62122 IEC:2002(E) – 9 –
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
consumer-use digital VTR
consumer-use video tape recorder using digital recording technology, 6,35 mm to 12,65 mm
width videotape and bandwidth compression technology for the image signal. Two tape formats
are standardized, as defined in the following two definitions. Although different formats may be
introduced in the future, fundamental measuring methods can be adapted to all formats
3.1.1
DV format
6,35 mm helical-scan VTR standardized in IEC 61834
3.1.2
D-VHS format
12,65 mm helical-scan VTR which will be standardized in the near future. Until then, refer to
the outline of the D-VHS format in documents [1] and [2]
3.2
ferrofluid development
direct observation of the magnetization on the videotape by the adherence of iron powder to its
surface by dipping the tape into a fluid containing powder of fine iron in order to observe the
recorded pattern using a microscope
3.3
byte
unit which separates the information series 1 into m bits. m usually consists of 8 bits, but not
always
3.4
error rate
ratio of the number of erroneous elements to the total number of elements reproduced and/or
transmitted during a given time interval
NOTE 1 The elements may be, for example, digits, code words or blocks.
NOTE 2 “Error ratio” is defined in similar terms as in IEV 704-18-03.
3.5
byte error rate
error rate for a signal constructed from byte units
(number of erroneous byte units)/(total number of elements of byte units)
3.6
MPEG-2 transport stream
MPEG-2 TS
data transmission format standardized by ISO/IEC MPEG (Moving Picture image coding
Experts Group)
3.7
three dimensional (3D) signal processing
TV video signal process taken from three viewpoints: the horizontal and vertical directions and
the time domain. Generally, it contains the operation processing between the fields or between
frames using a field memory or a frame memory
———————
Figures in square brackets refer to the Bibliography.
– 10 – 62122 IEC:2002(E)
3.8
audio operational output voltage
standard output voltage specified by the manufacturer for the audio analogue signal interface
between equipment when the output terminal is terminated by a specified load impedance
3.9
audio operational input voltage
input voltage specified by the manufacturer to generate the audio operational output voltage at
the output terminal
3.10
audio maximum output voltage
maximum audio output voltage that a VTR under test can generate. In this standard, it is the
voltage for an output signal of 3 % harmonic distortion, or it can be the voltage just before
clipping when the output signal is digitally clipped
4 Measuring conditions
4.1 General
All measurements shall be carried out in the environmental conditions specified by the
manufacturer.
If not otherwise stated by the manufacturer or by the format standard, the device under test
shall be conditioned for at least 3 h before measurement begins. An adequate warm-up time
may be used instead of 3 h conditioning.
The environmental conditions during measurement, at least the temperature and the relative
humidity, shall be recorded together with the presentation of the results of the measurements.
4.2 Environmental conditions
The environmental conditions for the measurements shall be:
Ambient temperature:
20 °C ± 1 °C
Relative humidity: 50 % ± 2 %
Air pressure:
96 kPa ± 10 kPa
Ambient temperature can be within a range of 5 °C and 35 °C, and relative humidity within a
range of 45 % and 75 % if these tolerances do not affect the results of measurement. Record
the temperature and humidity at the time of measurement along with the results of the
measurement.
4.3 Power supply
Use the power supply that conforms to the power requirements for the VTR under test. Voltage
regulation shall be ±2,5 % or better. The frequency fluctuation shall be ±1 % or better and the
harmonic content shall be 2 % or less.
4.4 Test signal
Use the test signals specified below for measurement.
4.4.1 Video test signal
Use a video test signal which has a 100 % amplitude level white signal of 4 µs inserted in every
horizontal period so that the results of measurement do not include errors caused by
disturbance of the video AGC circuitry of the VTR under test. A video test signal which contains
62122 IEC:2002(E) – 11 –
the 100 % level white signal over eight horizontal video periods inserted in every vertical
blanking period may be used as an alternative.
4.4.2 Colour bar signal
Use the standard colour bar signal that conforms to the ITU-R BT.471-1 type (b).
4.4.3 Video input signal for measuring audio characteristics
When measuring the audio characteristics for analogue in and analogue out, the colour bar
signal of 4.4.2 shall be applied to the VTR and recorded simultaneously with an audio test
signal to stabilize the VTR synchronization.
4.5 Measuring instruments
4.5.1 Noise meter
Frequency bandwidth
Luminance: 0,1 kHz to 10 MHz
Chrominance:
3,58 MHz ± 1,5 MHz (NTSC)
4,43 MHz ± 1,5 MHz (PAL)
Cut-off frequency
HPF: 0,1/100 kHz
LPF: 0,5/3,0/4,2/6,0 MHz/THROUGH
Input signal
For luminance S/N: white signal with superimposed signal
(level of 230 mVp-p or less)
For chrominance S/N: white signal with superimposed single colour signal,
modulated carrier
Measuring method
Luminance: 0 dB = 0,714 V (RMS value) for NTSC
0 dB = 0,700 V (RMS value) for PAL.
Chrominance AM noise: RMS value of detected AM noise
Chrominance PM noise: RMS value of detected PM noise
Gated noise position: Not gated until 4 µs before rising edge of white signal
Output noise signal: Not saturated by the input signals specified above
Input terminal: Composite video input terminal and Y/C separate
signal input terminal such as S Video terminal
4.5.2 Audio signal generator
Frequency range: 4 Hz to 20 kHz in sinusoidal wave form
Output voltage: Not less than 2 V
Total harmonic distortion: Less than 0,001 % in the frequency range of 20 Hz to 20 kHz
4.5.3 Audio level meter
This meter shall measure the true root mean square voltage of an a.c. waveform. But an a.c.
voltmeter with the scaling of root mean square value that measures the average value of
rectified voltage is applicable for the measurements of sinusoidal waveform voltage.
– 12 – 62122 IEC:2002(E)
Accuracy:
Within ±2 % in the frequency range of 4 Hz to 20 kHz
Range: –90 dB(V) to +20 dB(V)
4.5.4 Audio mixed frequency oscillator
This instrument shall generate a waveform of two sinusoidal signals that are mixed in a specific
ratio. Total harmonic distortion of each sinusoidal signal shall be less than 0,001 %.
4.5.5 Audio harmonic distortion meter
This meter shall measure residual harmonic and noise components with the exception of the
fundamental component.
Indication accuracy:
Within ±3 %
Minimum measurable value: Less than 0,001 % (The full-scale is 0,01 %)
Input impedance:
More than 100 kΩ
4.6 Video test tape
Use the video test tape which conforms to the video tape specifications of the VTR under test.
Record the type of the tape and the name of the manufacturer of the tape with the results of
measurement.
5 Methods of measurement for mechanical characteristics
5.1 General
The calibration tape that is prepared by the format supplier can confirm general
interchangeability.
The tape pattern of a digital VTR is the same helical-scan system as that used in an analogue
VTR, and can be observed by ferrofluid development. Digital VTR has a different tracking
system from existing systems and has a high-density recording system. The measuring
conditions will be clarified and the means of obtaining high measurement accuracy will be
described.
5.2 Tape speed
To obtain the tape speed, observe the magnetization pattern of the tape by a ferrofluid
developed tape on which a specified test signal is recorded.
5.2.1 Test signal
a) For DV format:
The test signal shall be a sinusoidal waveform whose wavelength is about 1,6 µm on the
-1
tape. In the case of the DV format 9 000 min system, the frequency is 6 MHz.
b) For D-VHS format:
The test signal shall be a MPEG-2 TS.
5.2.2 Measurement
Record the test signal and develop the tape by the ferrofluid development. Then using a
microscope, observe the magnetized pattern along the longitudinal line in the middle of the
tape for more than 30 mm. Obtain the same azimuth track interval p using the following
62122 IEC:2002(E) – 13 –
equation and referring to figure 2. For the D-VHS format, obtain the CTL pulse pitch p in the
same way.
l
p = mm
n
where
l is the distance of the measurement;
n is the number of the same azimuth tracks (or the number of the CTL pulses) over the
distance l.
Use the following equation to obtain the tape speed v:
p
v = × v mm/s
r
p
r
where, for the DV format
-3
Reference pitch per 2 tracks p = 2×10×10 /sin(θ ) mm
r r
Track angle θ = 9,1668°
r
Reference speed v = 18,831/1,001 mm/s for NTSC
r
18,831 mm/s for PAL
For the D-VHS format:
p , θ , v : refer to the D-VHS format.
r r r
If the VTR under test can be operated at more than one tape speed, measurements shall be
repeated at each of the speeds and the mode used for each test shall be stated.
5.2.3 Presentation of the results
Tape speed: mm/s ( mode)
5.3 Flatness of the RF envelope
This is the ratio of the minimum amplitude of the RF envelope at the head amplifier output with
respect to the maximum amplitude.
5.3.1 Test signal
a) For DV format, the test signal shall be the colour bar signal of 4.4.2.
b) For D-VHS format, the test signal shall be a MPEG-2 TS.
5.3.2 Block diagram
See figure 3.
5.3.3 Measurement
Record and reproduce the test signal, and observe the RF signal at the head amplifier output
on the oscilloscope. Obtain the maximum amplitude of the RF envelope, e , and the
max
minimum amplitude, e (figure 4).
min
The flatness of the RF envelope is:
e
min
Flatness = ×100 %
e
max
– 14 – 62122 IEC:2002(E)
5.3.4 Presentation of the result
Flatness of the RF envelope: %
5.4 Linearity
This measurement determines the track displacement using the ferrofluid development
method, using the cross-tape track measurement technique which has been used for
conventional analogue VTRs.
5.4.1 Test signal
a) For the DV format, the test signal shall be a sinusoidal waveform whose wavelength is
−
about 1,6 μm on the tape. In the case of the DV format 9 000 min system, the frequency
is 6 MHz.
b) For the D-VHS format, the test signal shall be an MPEG-2 TS.
5.4.2 Measurement
Record the test signal and develop the recorded tape by a ferrofluid. Measure the cross-tape
track height h , h , . h of the even track from the reference position (see figure 5 for the DV
1 2 n
format; figure 6 for the D-VHS format). Obtain each of the track location errors (linearity error)
using the following equation.
Δh = (h − h )cosθ
1 1 r r
Δh = (h − 2 × h )cosθ
2 2 r r
M
Δh = (h − n × h )cosθ
n n r r
where
Δh is the track location error, in μm
n
θ is the reference track angle, in °
r
is the reference cross-section track pitch (for 2 tracks)
h
r
1 v
h = 2 × T × × μm
r p
cosθ v
r r
v is the actual tape speed in mm/s
v is the reference tape speed in mm/s
r
For the DV format:
θ
= 9,1668 °
r
mm/s for NTSC
v = 18,831/1,001
r
18,831 mm/s for PAL
T = 10 μm
p
For the D-VHS format:
θ , v , T : refer to the D-VHS format.
r r p
The track location error (Δh , Δh . Δh ) shall be observed as shown in figure 7 and the peak-
1 2 n
to-peak value shall be obtained.
62122 IEC:2002(E) – 15 –
5.4.3 Presentation of the results
Linearity: μm p-p
5.5 Effective area starting position
This is the starting position of the track from the lower edge of the tape.
5.5.1 Test signal
a) For the DV format, the test signal shall be the colour bar signal of 4.4.2.
b) For the D-VHS format, the test signal shall be an MPEG-2 TS.
5.5.2 Measurement
Record the test signal and develop the recorded tape by a ferrofluid. Measure the distance
from lower edge of the tape to the track starting position, as shown in figure 8.
The track starting position is:
the front of the ITI signal for the DV format system,
the front of the sub-code signal for the D-VHS format system.
5.5.3 Presentation of the results
Starting position: mm
5.6 Track displacement measurement by image processing
A new and more reliable technique for measuring track displacement of high-density recorded
tape is presented here. An experimental report is given in the paper listed in the bibliography
under [3].
5.6.1 Measurement system
Figure 9 shows the block diagram of the measurement system. A tape that has been developed
with a ferrofluid is focused on a CCD (charge coupled device) camera through a microscope.
The tape is placed on a table that can move in the x and y directions, be rotated, and is
illuminated with a light source. The tape is adjusted so that the longitudinal direction of the tape
coincides with the x-axis of the table and x-axis of the CCD camera. The microscope magnifies
and focuses on the image of the tape so that an effective width of the tape is adjusted to the
width of the active image area of the CCD camera. A light from the light source illuminates the
tape, and reflection
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