SIST EN 61120-2:1999

SLOVENSKI STANDARD
01-april-1999
Digital audio tape recorder reel to reel system, using 6,3 mm magnetic tape, for
professional use -- Part 2: Format A (IEC 61120-2:1991)
Digital audio tape recorder reel to reel system, using 6,3 mm magnetic tape, for
professional use -- Part 2: Format A
Digitales Tonbandgerät - Spulensystem mit Magnetband 6,3 mm für Studioanwendung --
Teil 2: Format A
Système d'enregistrement à bande audionumérique, bobine à bobine, utilisant une
bande magnétique de 6,3 mm, à usage professionnel -- Partie 2: Format A
Ta slovenski standard je istoveten z: EN 61120-2:1993
ICS:
33.160.30 Avdio sistemi Audio systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEI
NORME
IEC
INTERNATIONALE
1120-2
INTERNATIONAL
Première édition
STANDARD First edition
1991-10
Système d'enregistrement à bande audio-
numérique, bobine à bobine, utilisant une bande
magnétique de 6,3 mm, à usage professionnel
2:
Partie
Format A
Digital audio tape recorder reel to reel system,
using 6,3 mm magnetic tape, for
professional use
Part 2:
Format A
ght — all rights reserved
© CEI 1991 Droits de reproduction réservés — Copyri
Aucune partie de
cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized
utilisée quelque
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électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission
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1120-2©IEC - 3 -
CONTENTS
Page
FOREWORD
Clause
1 Main track recording 7
1.1 Recording modulation method 7
1.2 Signal block structure 9
1.2.1 The word format
1.2.2 The block structure 9
1.2.3 Synchronization pattern
1.3 11 Signal word distribution to tracks
1.4 11 Error protection method
1.4.1 The error correction code
1.4.1.1 C2 Encoder
1.4.1.2 Cl encoder 17
1.4.2 Interleave sequence 19
1.5 Recording and reproducing characteristics 33
1.5.1 Reference tape 33
1.5.2 Calibration tapes 33
1.5.3 Procedure for adjusting recording current level and waveform 33
1.5.4 Specifications of tolerance relative to calibration tape 33
2 33
Sub-track recording
2.1 Digital recording method 33
2.1.1 Recording method on sub-track 2 33
2.2 Alignment of digital audio signals and sub-track signals 33
2.2.1 Alignment of cue audio-1 and cue audio-2 track signal 33
2.2.2 Alignment of time code track signal 35
3 Control word 35
3.1 Control word configuration 35
3.2 Control data assignment 35
3.3 Block address 39
3.4 C3 Encoder 39
- 5 -
1120-2©IEC
COMMISSION
INTERNATIONAL ELECTROTECHNICAL
DIGITAL AUDIO TAPE RECORDER REEL TO REEL SYSTEM,
USING 6,3 mm MAGNETIC TAPE,
FOR PROFESSIONAL USE
Part 2: Format A
FOREWORD
The formal decisions or agreements of the !EC on technical matters, prepared by Technical Committees on
1)
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 and they are accepted by the National
2)
Committees in that sense.
In order to promote international unification, the IEC expresses the wish that all National Committees
3)
should adopt the text of the IEC recommendation for their national rules in so far as national conditions will
permit. Any divergence between the IEC recommendation and the corresponding national rules should, as
far as possible, be clearly indicated in the latter.
of IEC 1120 has been prepared by Sub-Committee 60A: Sound recording, of IEC
This part
Technical Committee No. 60: Recording.
s 1 and 3 of this standard.
This part should be used in conjunction with pa rt
The text of this part is based on the following documents:
Report on Voting
Six Months' Rule
60A(CO)125 60A(CO)132
rt can be found in the Voting
Full information on the voting for the approval of this pa
indicated in the above table.
Report
The following IEC publications are quoted in this standard:
Digital Audio Tape Recorder reel to reel system, using 6,3 mm magnetic tape,
Publications Nos. 1120-1:
for professional use - Part 1: General requirements.
1120-3: Digital Audio Tape Recorder reel to reel system, using 6,3 mm magnetic tape,
for professional use - Part 3: Format B.
1120-4: Digital Audio Tape Recorder reel-to-reel system, using 6,3 mm magnetic tape,
for professional use - Part 4: Magnetic tape properties: Definitions and methods
of measurement. (Under consideration.)

1120-2 ç0 IEC - 7 -
DIGITAL AUDIO TAPE RECORDER REEL TO REEL SYSTEM,
USING 6,3 mm MAGNETIC TAPE,
FOR PROFESSIONAL USE
Part 2: Format A
Electrical requirements for recording and reproducing equipment.
1 Main track recording
Recording modulation method
1.1
In this subclause a method is first defined to convert binary data sequence of each of the
8 main digital tracks for recording on the magnetic tape. The second item described
in 1.2.3, is the definition of the synchronization pattern in recording code. The converted
code is given by NRZI.
The 2/4 M system is defined by dividing a binary data sequence into two-bit data
segments and converting these into four-cell codes using the data of the four bits
preceding and the four bits succeeding the two-bit data segment. The system uses the
collected data to convert the two-bit data segments into four-cell codes ensuring that no
less than two and no more than seven code cells "0" exist between any code cells "1" in a
sequence of converted code. The conversion rule is given by the following table.
2/4 M conversion table
Original Converted
Contents
data bits code cells
11 Y000
Unconditional
01 0010
10 0100 "E2 El " * "10" and "L 1 L2" = "00"
0001 2 E t " = "10" and "L 1 L2" = "00"
10 "E
= "10" and L4" = "00"
10 0000 "E2 El " = "10", "Li L2"
"L3
0100 "E2 El " * "10", "L1 L2" _ "10" and "L3 L4" = "00"
10 Y001 Except the foregoing
l" = "10" and "Li L2" # "01"
00 0000 E4 E3" # "10", "E 2 E
00 0001 E4 E3" * "10", "E2 E 1" = "10" and "L 1 L2" = "01"
0000 E4 E3" = "10" and "E 2 Et" = "10"
00 0100 Except the foregoing
where:
En = data bits preceded by n-bit, to 2-bit data to be converted in original data sequence
original data sequence
Ln = data bits succeded by n-bit, to 2-bit data to be converted in
Y complement logic of logical sum of two cells immediately before code bit. Y in the converted code
sequence
The converted code is given by NRZI.

-9-
1120-2 ©IEC
Signal block structure
1.2
1.2.1 The word format
The word slots to be recorded on the main tracks have 20 bits at speed I and 16 bits at
speed II.
PCM samples are specified as uniformly quantified and are represented in the form of sign
bit (MSB) leading.
1.2.2 The block structure
The following figure shows the data configuration and the contents of frames and blocks.
-> - c -*
d
4-- p -> F cw -^ F
Main
Cl (CRC)
PCM DATA or C2 CHECK track
SYNC CTRLW or C3
x
Frame configuration
Track 8
Cl (CRC)
SYNC C3 CHECK C2 CHECK
r
Cl (CRC) Track 7
C3 CHECK PCM DATA
SYNC
Cl (CRC) Track 6
BA PCM DATA
SYNC
Cl (CRC) Track 5
) SYNC BA PCM DATA
Track 4
PCM DATA Cl (CRC)
SYNC ID
Track 3
PCM DATA Cl (CRC)
SYNC ID
Cl (CRC) Track 2
C3 CHECK PCM DATA
SYNC
Cl (CRC) Track 1
C3 CHECK C2 CHECK
SYNC
Block configuration
Legend:
BA = Bloc address
ID = Identification data
Frame and block parameters:
p = 16 bits
SYNC length
cw = 8 bits
- Control word or C3 length
Data or C2 length d = 320 bits
c = 16 bits
C1 (CRC) length
bits
Frame length f = 360
b = 8 frames
Block configuration
- 11 -
1120-2 ©IEC
1.2.3 Synchronization pattern
ttern in recording code consists of 32 cells, in which the magnetiza-
The synchronization pa
tion reversion interval is confined within the rule of 2/4 M scheme, so as to protect the
overwrite characteristics from deterioration, and a pattern of lower cross correlation
function is chosen so as to let the probability of erroneous SYNC detection be reduced at
ern is represented in NRZI, and given
the vicinity of SYNC signal. The synchronization patt
as follows.
-00100001000100001001001000100000 —>
recording direction -
1.3 Signal word distribution to tracks
Input PCM samples of two audio channels are allocated for six tracks by a Matrix device
and additionally two tracks of C2-check data are encoded in the way described in the
following figure:
O 8(2), 8(1), 1(2), 1(1)
4(1), 3(1), 2(1), 1(1)
Track 2
Channel (1)
1 0(2), 10(1), 3(2), 3(1)
J
Track3
12(2), 12(1), 5(2), 5(1)
Trask 4
Matrix
2 2(1), 7(2), 7(1)
(2),
O
Trafic 5
4(2), 4(1), 9(2), 9(1)
O
Trafic 6
6(2), 6(1), 11(2), 11(1)
4(2), 3(2), 2(2), 1(2)
Trafic 7
Channel(2)
C2 Check
Trask 1
Encoder
C2 Check
Track 8
1.4 Error protection method
Error protection method is two dimensional. Error detection is made possible by the CRC
check word recorded for each frame of each track, and by the Reed-Solomon code. Error
correction is made possibly by the Reed-Solomon code with the aid of CRC check results.

1120-2 ©IEC – 13 –
1.4.1 The error correction code
The error correction code referred to as the RSC code shall be used. The RSC code is a
sub-class of the generalized product code. The code is constructed by the (16,12,5) Reed-
Solomon code over GF (2 8), as code C2, and by the (344,328,4) CRC over GF(2), as
code Cl. Symbol interleaving has been performed between C2 encoding and Cl
encoding. Generator polynomials for code C2, and code Cl are given by the following
equations:
Cl: G (x)=x1 16 +x12 +x5 +1
C2: G2 (x) = 7L (x - ai)
i =0
G 1 (x) is the generator polynominal based on CCITT V41 recommended 16-bit Cyclic
Redundancy Check (CRC) word:
a is the primitive element of GF (28).
The vector representation of a is
a• (0 0 0 0 0 0 1 0)
7 0
a a6 a5 a4 a3 a2 a1 a
and the primitive polynomial g(x) is
g (x) = x8 + x4 + x3 + x2 + 1
All elements are shown in the following table:

– 15 –
1120-2 O IEC
THE ELEMENT OVER GF (28)
Element Element Number Number Element Number
Number Element
192 10000010
128 10000101
00000001 64 01011111
129 00010111 193
00000010 65 10111110
194 00110010
130 00101110
00000100 66 01100001
195 01100100
131 010111100
67 11000010
3 00001000
196 11001000
68 10011001 132 10111000
4 00010000
01101101 197 10001101
69 00101111 133
5 00100000
134 11011010 198
70 01011110
6 01000000
10101001 199 00001110
71 10111100 135
7 10000000
01001111 200
72 01100101 136
8 00011101
137 10011110 201 00111000
73 11001010
9 00111010
00100001 202 01110000
74 10001001 138
10 01110100
01000010 203
75 00001111 139
11 11101000
140 10000100 204
76 00011110
12 11001101
00010101 205 10100111
77 00111100 141
13 10000111
206 01010011
142 00101010
78 01111000
14 00010011
207 10100110
143 01010100
79 11110000
15 00100110
144 10101000 208
01001100 80 11111101
145 01001101 209
81 11100111
17 10011000
146 10011010 210
82 11010011
18 00101101
211 10110010
10111011 147 00101001
19 01011010 83
148 01010010 212
10110100 84 01101011
213 11110010
149 10100100
21 01110101 85 11010110
01010101 214 11111001
22 11101010 86 10110001 150
151 10101010 215
23 11001001 87 01111111
152 01001001 216
24 10001111 88 11111110
10010010 217 10011011
25 00000011 89 11100001 153
218 00101011
154 00111001
26 00000110 90 11011111
219 01010110
10100011 155 01110010
27 00001100 91
220 10101100
156 11100100
28 00011000 92 01011011
221 01000101
93 10110110 157 11010101
29 00110000
222 10001010
94 01110001 158 10110111
30 01100000
223 00001001
11100010 159 01110011
31 11000000 95
224 00010010
11011001 160 11100110
32 10011101 96
225 00100100
161 11010001
33 00100111 97 10101111
162 10111111 226
34 01001110 98 01000011
227 10010000
10000110 163 01100011
35 10011100 99
228 00111101
00010001 164 11000110
36 00100101 100
165 10010001 229 01111010
37 01001010 101 00100010
230 11110100
01000100 166 00111111
38 10010100 102
231 11110101
103 10001000 167 01111110
39 00110101
00001101 168 11111100 232
40 01101010 104
233 11110011
105 00011010
...