ISO/IEC 8441-1:1991
(Main)Information technology — High density digital recording (HDDR) — Part 1: Unrecorded magnetic tape for (HDDR) applications
Information technology — High density digital recording (HDDR) — Part 1: Unrecorded magnetic tape for (HDDR) applications
This part of ISO/IEC 8441 specifies requirements for unrecorded magnetic tape designed for high density digital recording (HDDR) having the following characteristics: a) nominal thickness 25,4 urn (0,001 in); b) longitudinal magnetic orientation; c) coercivity 72 kA/m (900 Oe) max. These tapes are suitable for interchange in accordance with ISO/IEC 8441-2. Requirements for packaging are also included. NOTE 1 Tapes of coercivity above 32 kA/m (400 Oe) are usually classified as high energy tapes and users should establish compatibility with equipment used for driving them. Annex A gives guidance on glass and metal-flanged reels. Annex B gives information on the wear of recording heads. Different categories of environmental conditions and their effects on tape are dealt with in annex C. Severe operating conditions are considered in annex D. Surface electrical resistance testing is dealt with in annex E. A tape abrasivity testing technique is described in annex F. A list of bibliographical references is given in annex G. NOTES 2 It is recognized that archival interchange tapes, or those produced by systems in use prior to the publication of this part of ISO/lEC 8441, may not comply with the requirements and/or recommendations herein. 3 Various tests and procedures herein refer to recording with a.c. HF bias. In practice, certain HDDR systems do not use bias. The use of bias in this part of ISO/IEC 8441 does not imply that the tape so tested is in any way unsuitable for a biasless system.
Technologies de l'information — Enregistrement numérique à haute densité (HDDR) — Partie 1: Bande magnétique vierge pour les applications HDDR
General Information
Standards Content (Sample)
INTERNATIONAL
STANDARD 84414
First edition
1991-05-15
Information technology - High density digital
recording (HDDR) -
Part 1:
Unrecorded magnetic tape for (HDDR)
applications
Technologies de i’informa tion - Enregistrement numkrique 5 haute
densite (HDDR) -
Partie 1: Bande magnetique vierge pour les applications HDDR
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--____I_ ISO/IEC 8441-1:1991(E)
~__-----
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ISOAEC 8441=1:1991(E)
Contents
Paqe
.
1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.
1 Scope .
1
.................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Normative references
................................. 1
3 Definitions
3
... ..............................
4 General . . .
3
4.1 Materials . .
3
.....................................................................................
4.2 Tape reels
3
4.3 Tape wind . .
3
4.4 Packaging .
rj
3
5 Test conditions .
3
5.1 General . .
3
..................................................................................
5.2 Conditioning
3
.............................................. ............................
5.3 Test environment
3
6 Dimensions .
........ 3
6.1 Tape width . .
4
6.2 Tape length .
4
..............................................................................
6.3 Tape thickness
4
.........................................................................
7 Physical properties
4
7.1 Yield strength . .
4
7.2 Elongation under stress .
5
....................................................................................
8 Performance
5
8.1 Reference test system .
5
......................................................................................
8.2 Sensitivity
............................ 5
8.3 Wavelength response .
............................................ 6
8.4 Output level uniformity (long term)
6
....................................
8.5 Instantaneous nonuniformity (dropouts)
0 ISO/lEC 1991
All rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, Including photocopylng and microfilm, without
permission in writing from the publisher.
lSO/lEC Copyright Office l Case Postale 56 l CH-1211 Genkve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 2 ----------------------
EC 8441=1:1991(E)
..s.............*........... 6
8.6 Signal-to-noise ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
............................................. ............................... 8
8.7 Ease of erasure
....... ................................ ................ 7
8.8 Electrical surface resistance
........................................................ 9
8.9 Environmental performance
8.10 Durability . 9
9
Abrasivity .
8.11
Annexes
.......... IO
A Glass- and metal-flanged tape reels .
11
B Wear of recording heads .
12
C Environmental conditions . . .
12
Cl General .
......... 12
C.2 Normal operating conditions .
................................................. 12
C.3 Extended operating conditions
.................................................. 12
C.4 Severe operating conditions3)
C.5 Shipping and short-term storage . . 12
............................ 12
C.6 Extended shipping and short-term storage
12
C.7 Recommended long-term storage .
C.8 Deterioration of tape arising from exposure to adverse
......................................................... 12
environmental conditions
..................... .................................. 14
D Severe operating conditions
14
D.1 Application .
......... .................................................................... ..... 14
0.2 Conditions
0.3 Environmental performance tests for limited duration recording
under severe conditions . . 14
.............................................. 14
0.3.1 Definition of severe conditions
14
0.3.2 Requirement .
........................................................................ 14
D,3,3 Test procedure
16
E Surface electrical resistance testing .
........................................ 16
E.1 Scope .
......................................... .............. 16
E.2 Test specimens .
16
E.3 Apparatus .
16
E.3.1 Electrodes for testing insulation resistance .
.
. . .
III
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ISO/IEC 8441=1:1991(E)
........ 16
E.3.2 Electrodes for testing volume and surface resistance
16
E.3.3 Electrode materials .
potential . 16
E.3.4 Direct-current
E.3.5 Measuring equipment . 17
.............................. 17
E.3.6 Switches and keys .
................................... 17
E.4 Procedure .
..................................................... 17
E.4.1 Conditioning of specimens
..................................... 17
E-4.2 Precautions in mounting specimens
resistance . 17
E.4.3 Method of measuring
...................................... 19
E.4.4 Insulation resistance determination
.................... 19
E.4.5 Volume and surface resistance determination
.......................................... 20
E.4.6 Surface resistance determination
................................ 21
E.5 Report .
.................................... 26
F Tape abrasivity testing .
..................... 26
F.1 Scope .
...................................................................................... 26
F.2 Principle
26
Apparatus .
F.3
26
Sensor . .
F.3.1
26
F.3.2 Dummy head assembly . .
26
F.3.3 Tape abrasivity meters) .
26
F.3.4 Reference tapes) .
........................... 26
F.4 Procedure .
........................................................ 26
F.4.1 Cleaning and measuring
........................................ 27
F.4.2 Requirement . .
.......................... 28
G Bibliography .
iv
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ISO/IEC 8441=1:1991(E)
Foreword
IS0 (the International Organization for Standardization) and IEC (the
International Electrotechnical Commission) form the specialized system
for worldwide standardization. National bodies that are members of IS0
or IEC participate in the development of International Standards through
technical committees established by the respective organization to deal
with particular fields of technical activity. IS0 and IEC technical com-
mittees collaborate in fields of mutual interest. Other international or-
ganizations, governmental and non-governmental, in liaison with IS0
and IEC, also take part in the work.
In the field of information technology, IS0 and IEC have established a
joint technical committee, ISO/IEC JTC 1. Draft International Standards
adopted by the joint technical committee are circulated to national bod-
ies for voting. Publication as an International Standard requires ap-
proval by at least 75 % of the national bodies casting a vote.
International Standard lSO/IEC 8441-1 was prepared by Joint Technical
Committee ISO/IEC JTC 1, Wormafion technology.
ISO/IEC 8441 consists of the following parts, under the general title In-
formation technology - High density digital recording (HDDR):
- Part 1: Unrecorded magnetic tape for (HDDR) applications
c
- Part 2: Guide for interchange practice
Annexes A, B, C, D, E, F and G of this part of ISO/IEC 8441 are for infor-
mation only.
---------------------- Page: 5 ----------------------
ISO/IEC 8441-1:1991(E)
Introduction
This part of ISOAEC 8441 gives guidance on the performance levels of
unrecorded tape suitable for high density digital recording for inter- 5
change purposes. It should be noted that the performance levels speci-
fied may differ from those attained at the time of purchase of the tape.
---------------------- Page: 6 ----------------------
ISOllEC 8441-1:1991(E)
INTERNATIONAL STANDARD
Information technology - High density digital recording
(HDDR) -
Part 1:
Unrecorded magnetic tape for (HDDR) applications
3 Various tests and procedures herein refer to recording
1 Scope
with a.c. HF bias. In practice, certain HDDR systems do
not use bias. The use of bias in this part of ISO/IEC 8441
does not imply that the tape so tested is in any way un-
suitable for a biasless system.
This part of ISO/IEC 8441 specifies requirements for
unrecorded magnetic tape designed for high density
digital recording (HDDR) having the following
2 Normative references
characteristics:
The following standards contain provisions which,
a) nominal thickness 25,4 urn (0,001 in);
through reference in this text, constitute provisions
of this part of ISO/IEC 8441. At the time of publica-
b) longitudinal magnetic orientation;
tion, the editions indicated were valid. All standards
are subject to revision, and parties to agreements
c) coercivity 72 kA/m (900 Oe) max.
based on this part of ISO/IEC 8441 are encouraged
to investigate the possibility of applying the most
These tapes are suitable for interchange in accord-
recent editions of the standards indicated below.
ance with ISO/IEC 8441-2.
Members of IEC and IS0 maintain registers of cur-
rently valid International Standards.
Requirements for packaging are also included.
IS0 1184:1983, Plastics - Determination of tensile
NOTE 1 Tapes of coercivity above 32 kA/m (400 Oe) are
properties of films.
usually classified as high energy tapes and users should
establish compatibility with equipment used for driving
them.
IS0 1860:1986, Information processing - Precision
reels for magnetic tape used in interchange instru-
Annex A gives guidance on glass and metal-flanged
mentation applications.
reels. Annex B gives information on the wear of re-
cording heads. Different categories of environmental
conditions and their effects on tape are dealt with in
annex C. Severe operating conditions are con- 3 Definitions
sidered in annex D. Surface electrical resistance
testing is dealt with in annex E. A tape abrasivity
For the purpose of this part of ISO/IEC 8441, the fol-
testing technique is described in annex F. A list of
lowing definitions apply.
bibliographical references is given in annex G.
NOTE 4 Tape speed is taken to be 3048 m/s (120 in/s),
NOTES
unless otherwise stated.
2 It is recognized that archival interchange tapes, or
3.1 abrasivity: The propensity of a magnetic tape to
those produced by systems in use prior to the publication
cause wear of a recording head, by the passage of
of this part of ISO/lEC 8441, may not comply with the re-
quirements and/or recommendations herein. the tape over the head.
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ISOAEC 844%1:1991 (E)
NOTES duration, in microseconds, for a tape speed of 3048 m/s
(120 in/s) (for a general definition, see ISO/IEC 8441-2).
5 It may be expressed as micrometres of head wear per
metre of tape passed (microinches per inch), or as a value
3.8 operating bias current: That bias current
relative to a given reference tape.
through the recording head which gives a 2 dB fall-
off (overbias peak) of the peak output from the ref-
6 The actual wear produced in the recording head will
erence tape when a 2,0 MHz signal is recorded at
also depend on the tape speed and tension (see
reference level (see 3.13), at a tape speed of
annex B).
3048 m/s (120 in/s).
3.2 durability: The ability of a tape to maintain its
3.9 output level uniformity (long term): The differ-
output uniformity and dropout characteristics after
ence between the maximum and minimum peak
a given number of passes on the reference test re-
output levels, the peak value in either case being the
corder.
value that contains 95 % of the peaks (see figure 1
and 8.4).
3.3 ease of erasure: The ability of a specified eras-
ing field to effect a specified reduction in the level
of a signal recorded on a tape.
95 % probability band Envelope of peak amplitudes
r /
3.4 electrical surface resistance: The surface re-
sistance, in ohms per square, of the magnetic coat-
ing or the back surface of a tape, as appropriate.
NOTE 7 The SI unit of surface resistivity is the ohm, al-
though ohms per square is used in practice.
Replayed frequency 1 MHz
Tape speed 1,524 m/s (60 in/s)
3.5 elongation under stress: The increase in the
distance between reference lines on the test piece
due to a tensile load, expressed as a percentage of
the initial distance between the reference lines.
Short-term uniformity (see 8.5) : 10 s
3.6 E value: The radial distance by which the reel
Long-term uniformity (see 8.6) : entire tape
flanges extend beyond the outermost layer of tape
wound on a reel under a tensile force of 0,109 N/mm
+ 0,033 N/mm of tape width (10 ozf/in + 3 ozf/in of
-
tape width).
NOTE 8 0,109 N/mm + 0,033 N/mm is equivalent to
282 gf/in + 85 gf/in. -
-
Measurement time, t
1/1
3.7 instantaneous nonuniformities (dropouts): A
Deviation from uniformity = 20 loglo V,- dB
tape defect which causes a reduction in the repro-
duced signal amplitude sufficient to jeopardize or
Figure 1 - Replayed waveform for output
impair data recovery.
uniformity test
For the purpose of this part of ISO/IEC 8441, the on-
set of a dropout event is denoted by a 12 dB re-
duction in the output level from a 0,635 mm (0,025 in)
3.10 reference tape: An unrecorded length of tape
wide track of a 1,524 pm (60 pin) wavelength test
used as a reference.
signal recorded as a square wave slightly above
saturation level (see 8.5.1). The end of a dropout
NOTE 11 The reference tape should be one adopted by
event is denoted by recovery of the signal to within
agreement between the interchange parties. When abso-
9 dB of the average level.
lute quantitative performance levels and an international
source of standard reference tapes have been estab-
NOTES
lished, such agreements may be replaced by reference to
standard reference tapes.
9 The dropout count associated with each dropout event
is the duration of the event expressed as one-half of the
3.11 reference head: A head used in conjunction
number of test signal periods occurring during the dropout
event. with the reference tape.
10 For a tape speed of 3 048 m/s (120 in/s) the test signal NOTE 12
The reference head should be agreed on be-
period is 0,5 ps. Hence, the dropout count is equal to the tween the interchange parties.
2
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ISO/IEC 8441=1:1991(E)
ries B and C (see IS0 8441-2, annex A) because they are
3.12 reference output level: The reproduce level of
known to give improved performance and greater pro-
a 200 kHz signal recorded on the reference tape at
tection against dropouts, especially if combined with pro-
6 dB below standard record level 3048 m/s
tecting collars.
(120 in/s) and with operating bias current.
4.3 Tape wind
3.13 reference record level
Th e tape be wound with the magnetic coated
shall
3.13.1 with a.c. bias: The input level of a 200 kHz
su rface in nerm ost.
signal recorded on the reference tape at 3048 m/s
(120 in/s), with operating bias current such that on
NOTE 14 This is sometimes called “A” wind.
play back, the output signal has 1 % third-harmonic
distortion as measured with a wave analyser.
4.4 Packaging
3.13.2 without ax, bias: The record head reference
Each reel shall be enclosed by an individual wrap-
current level without a.c. bias (generally expressed
per (e.g. polyethylene) packaged in an appropriate
in milliamperes peak-to-peak) is established in ac-
container which provides support of the enclosed
cordance with ISCYIEC 8441-2. The same current
reel at the hub.
If windowless flanges with
level (in milliamperes) established at the record
wraparound bands are used, the wrapper may not
head to 200 kHz and for tape speed 3084 m/s
be necessary.
(120 in/s) is defined as the reference record level.
3.14 secondary reference tape: An unrecorded
5 Test conditions
length of tape, the magnetic characteristics (i.e.
sensitivity, wavelength response, bias character-
5.1 General
istic, distortion characteristics), of which have been
calibrated against the reference tape.
For all procedures described in this part of
ISO/IEC 8441, conditioning shall be as specified in
3.15 sensitivity: The output of the tape sample un-
5.2, and in the test environment as specified in 5.3.
der test compared to that from the reference tape
expressed as a ratio, normally quoted in decibels,
5.2 Conditioning
the frequency being 200 kHz in both cases.
Conditioning shall be carried out in the test en-
3.16 signal-to-noise ratio: The ratio of the repro-
vironment (see 5.3). The tape may be tissue cleaned.
duced signal power from a tape and the wideband
It shall be wound and rewound with a tensile force
noise power (tape and equipment) measured over
of 0,109 N/mm + 0,33 N/mm of tape width (10 ozf/in
the system bandwidth.
+ 3 ozf/in of tape width). The tape shall then be
Gored, unwrapped, for a minimum of 24 h to allow
3.17 wavelength response: The output voltage fre-
it to stabilize.
quency characteristic of the tape when normalized
to a specific wavelength compared to the response
0,109 N/mm + 0,033 N/mm is equivalent to
NOTE 15
of the reference tape.
282 gf/in + 85 gf/in. -
-
4 General 5.3 Test environment
The test environment shall be as follows:
4.1 Materials
a) Temperature: + 23 “C + 3 OC (-I- 73 OF & 5 OF)
The tape shall consist of a uniform layer of
ferromagnetic material held in a flexible binder me-
b) Relative humidity: 45 % to 55 %
dium on a suitable continuous and splice-free, flex-
ible base material with a conductive back coating.
6 Dimensions
4.2 Tape reels
6.1 Tape width
The tape shall be wound on reels in accordance with
The tape width shall be one of those given in
IS0 1860.
table I.
NOTE 13 Glass-flanged reels are preferable to reels
with metal flanges, with or without window slots (see an- NOTE 16 The metric and imperial dimensions are not
nex A), particularly for recorders in performance catego- exact conversions.
---------------------- Page: 9 ----------------------
ISO/IEC 8441=1:1991(E)
In case of doubt or dispute, the imperial values shall
7 Physical properties
be used to determine compliance with this part of
ISO/IEC 8441.
7.1 Yield strength
Table 1 - Tape widths
Millimetres Inches
7.1 .I Procedure
r--- -
12,65 + 0,025 0,498
+ - 0,001
-
Test five samples in accordance with IS0 1184, ex-
25,35 + 0,025 0,998 + - 0,001 cept that
-
50,75
+ 0,025 1,998 + - 0,001
-
a) the minimum tape length is 200 mm (8 in);
b) the initial jaw separation is 100 mm (4 in);
c) the rate of jaw separation is 0,8 mm/s 2 in/min).
6.2 Tape length
7.1.2 Requirement
The tape length shall be as given in table 2 for the
appropriate reel diameter.
The tensile load at the 1 % offset yield po nt (as de-
fined in IS0 1184) shall not be less than 2,lO N/mm
(12 Ibf/in) of tape width, even if the tape breaks prior
to reaching the 1 % offset yield point.
NOTE 17 2,10 N/mm is equivalent to 5,44 kgf/in.
6.3 Tape thickness
The tape thickness is controlled by, and specified in
terms of, the “E” value (see 3.6). The nominal thick-
7.2 Elongation under stress
ness of the magnetic coating is 5 pm (200 pin), and
the nominal tape thickness is 25 pm (0,001 in). The
“E” value shall be at least 2,54 mm (0,l in) for reels 7.2.1 Procedure
having a diameter up to and including 203 mm (8 in),
and shall be at least 3,18 mm (0,125 in) for reels Test at least five sample lengths of each type of
having a diameter greater than 203 mm (8 in). tape. Select sample lengths of 600 mm (24 in) mini-
mum. Clamp each sample at one end and make a
transverse length reference mark approximately
- Tape lengths
Table 2
500 mm (20 in) from the point of clamping. Allow the
Nominal reel
samples to hang freely in the test environment (see
ft
diameter m
5.3) for at least 24 h.
670
Attach a 50 g (2 oz) weight to the free end of each
203 mm (8 in) Minimum length’) 2210
674
sample. Measure the distance between the clamp-
ing point and the reference mark with an accuracy
1400
4 625
267 mm (IO,5 in) Minimum length’) of + 0,25 mm (0,010 in), taking care that the tape is
1410
tensioned only by the 50 g (2 oz) weight. Note this
length for each sample. This is the pre-stress length
2 200
7 230
318 mm 12,5 in) Minimum length’)
2 204 measurement.
Remove the 50 g (2 oz) weight and attach a weight
2 800
Minimum length’) 9 235
356 mm 14 in)
2815
corresponding to a tension of I,75 N/mm (10 Ibf/in)
of tape width to each sample below the reference
3 290
mark. Note the time of attachment to each sample.
381 mm 15 in) Minimum length’) 10795
3 303
Allow the stressed samples to hang undisturbed for
180 min + 3 min. Attach a 50 g (2 oz) weight to each
3 800
12440
406 mm (16 in) Minimum length’)
sample and measure the distance between the
3 822
clamping point and the reference mark with an ac-
curacy of + 0,25 mm (0,010 in), noting the length for
1) The minimum lengths are specified on the basis
each sample as before. This is the post-stress length
of tapes with a nominal thickness of 25 blrn (0,001 in),
measurement.
and the “E” values given in 6.3. “E” values less than
those given in 6.3 will result in longer tapes.
NOTE 18 I,75 N/mm is equivalent to 4,53 kgf/in.
4
---------------------- Page: 10 ----------------------
ISO/IEC 8441-1:1991(E)
IS0 8441-2 [I4 tracks on 12,7 mm (0,5 in), or
7.2.2 Requirement
28 tracks on 25,4 mm (1,O in), using head seg-
ments with a track of 0,635 mm rt. 0,025 mm
The difference between the pre-stress and post-
(0,025 in + 0,001 in)].
stress lengths for each sample shall not exceed
0,5 %.
d) Perform the measurements at a tape speed of
3048 m/s (120 in/s), except where another speed
7.2.3 Full reel moment of inertia
is specified.
The maximum moments of inertia for full reels of
e) Ensure that the recorder electronics are properly
tape are given in table 3.
terminated.
8 Performance
f) Specify all test signals.
8.1 Reference test system
8.2 Sensitivity
8.1 .I System components
8.2.1 Procedure
The reference test system shall consist of a refer-
For each type of tape to be tested, establish the ap-
ence tape and reference head mounted on a
plicable reference output level to calibrate the ref-
referred to as the reference
recorder/reproducer,
erence recorder for the sensitivity measurement.
recorder, which shall have a wideband 2,0 MHz ca-
pability at 3,048 m/s (120 in/s) tape speed as defined
A 200 kHz signal shall be recorded at 6 dB below
in IS0 8441-2, and preferably a facility to clean the
reference record level (see 3.13). Note the equaliz-
tape during recording and playback.
ation settings and the reproduce amplifier gain set-
tings when establishing the reference output level.
8.1.2 Preparation of recorder for testing Reproduce the tape and measure the recorder out-
put.
The reference recorder shall be set up as follows:
8.2.2 Requirement
a) Thoroughly clean and demagnetize the recorder
and adjust the heads for correct azimuth (see
The output from a test sample, excluding the first
IS0 8441-2).
and last 2 % of its length, shall not vary throughout
its length from the reference output level by more
NOTE 19 Cleanliness is particularly critical in drop-
than + 2 dB.
-
out assessment (see 3.7).
8.3 Wavelength response
0,109 N/mm
b) Set the tape tension of
+ 0,033 N/mm of tape width (IO ozf/in - + 3 ozf/in
(See 3.17.)
of tape width).
8.3.1 Procedure
NOTE 20 0,0109 N/mm + 0,033 N/mm is equivalent
to 282 gf/in + 85 gf/in. -
Repeat the procedure described in 8.2.1 at each
frequency given in table 4 for each type of tape being
c) Ensure that the record and reproduce head seg-
tested, avoiding the use of edge tracks, and ignoring
ments and the head configuration comply with
the first and last 2 % of the tape length.
in table 2 or table 4 of
the dimensions given
Table 3 - Maximum moments of inertia for full reels
Nominal reel diameter
I I
t I i
355 mm 381 mm 406 mm
266 mm 318 mm
203 mm
Nominal tape width
(12,5 in) (14,O in) (15,O in) (16,0 in)
(8,0 in) (lo,5 in)
I
I
I 4
1 1 1 1 1
I bYI* g-m* 1 1 bTt* bTt* g-m* g-m* I I b*ft* b*ft* g-m* g-m* I I b-ft* b-ft*
g-m* I b-ft* g-m* lb-ft* g-m*
6,30 mm (0,25 in) 2,78 0,066 IO,46 0,24 1 4 9,72 0,468 29,84 0,707 0,707 44,75 44,75 0,989 0,989 54,27 54,27 I,29 I,29
42,70 mm (0,50 in) 3,77 0,089 4 4,57 0,345 28,44 0,667 43,24 I,02 I,02 59,78 59,78 ?,42 ?,42 77,79 77,79 I,84 I,84
25,40 mm (I,00 in) 5,73 0,136 23,37 0,554 44,97 I,07 69,99 I,66 I,66 95,82 95,82 2,27 2,27 4 4 24,8 24,8 2,96 2,96
~ 50,80 mm (2,00 in) 9,66 0,229 40,97 4 23,55 2,93 2,93 4 4 67,92 67,92 3,98 3,98 248,86 248,86 5,49 5,49
0,97 4 78,63 I,86
I
1 I
I I I I
I
5
---------------------- Page: 11 ----------------------
ISO/IEC 8441-1:1991 (E)
8.3.2 Requirement 8.5 instantaneous nonuniformity (dropouts)
The output at each frequency, when normalized to
8.51 Procedure
the output at 15 pm (600 pin) and compared to the
response of the reference tape, shall be within the
On at least every other track (seven tracks) of either
limits given in table 4.
the odd or the even head of a 28 track assembly,
record either a 2 MHz square wave signal at
- Wavelength response 3048 m/s (120 in/s), or a 1 MHz squarewave signal
Table 4
at I,52 m/s (60 in/s) throughout the entire tape
Test frequency
length. Set the reference record level (see 3.13). For
Requirement
Recorded
at tape speed
variation from play back, use a reproduce amplifier (with no AGC
of 3,048 m/s wavelength
reference tape
device) and a threshold detector with hysteresis
(120 in/s)
able to monitor the output signal and detect any
amplitude loss and recovery to the limit stated in
kHz llrn (in.lO--3 ) dB
3.7. The signal-to-noise ratio of the test signal at the
input to the threshold detector should be at least
3810 (150) +2
078
25 dB. The reference level for dropout detection
254 (10) +2
12 -
shall be established by averaging the test signal
output amplitude over IO m (33 ft) tape length in the
120 25,4 (1‘00) +2
-
vicinity of any dropout.
480 6,35 (0,250) +2
-
960 3,18 (0,125) + 2,5
-
For each of the seven tracks tested, note the accu-
mulated dropout count, where the count for each
1200 2,54 (0,100) + 2,5
-
dropout corresponds to one-half the number of pe-
1500 2,03 (0,080) 3-3
-
riods of the test frequency affected (see 3.7).
2 000 1,52 (0,060) 23
NOTE 22 Results obtained from this test shall state
whether or not ax. bias was used.
8.4 Output level uniformity (long term)
8.5.2 Requirement
(See 3.9.)
The accumulated dropout count on any tested track
shall be less than 1 per 10 m (I per 32,8 ft) of tape
8.4.1 Procedure
length averaged along the enti
...
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