1、EUROPEAN STANDARD EUROPISCHE NORM NORME EUROPENNE EN 61120-3 October 1993 Dewripti IIS: Audio recording. dit;il recording, iiiagtietic tape, code, format, recording characteristics, recording track English version Digital audio tape recorder reel to reel system, using 6,3 mm magnetic tape, for profe
2、ssional use Part 3: Format B (IEC 1120-3: 1991) Systme denregistrement bande audionumrique, bobine bobine, utilisant une bande magntique de 6,3 mni, usage Partie 3: Format B Digitales lbnbandgert Spuleiisystein mit Magnetband 6,3 mm fiir Studioiendiigei Teil 3: Format B professionnel (IEC 1120-3: 19
3、91) (CE1 1120-3: 1991) This European Standard was approved by CEXELEC on 1003-09-22. CENELEC members are bound to comply with the CENXENELEC Internal Regula%ions which stipulate the conditions for giving this European Standard the status of a national standard withorit any alteration. I the output w
4、aveform is polarity-free. Rules for generating a pair of output waveform cells for each input bit are defined in the following formulation and bit to waveform transitions are defined in rules 1 and 2. * Formulation for bit to waveform modulation. - - _- T = EDGE. (X2.Xl)I + EDGE.(X2.Xl.Tl+X2.X1 .XO.
5、Tl.T2+X1 .X2.X9X4.T2T4.T6) Xi = INPUT BIT DELAYED BY i BIT CLOCKS TI = OUTPUT WAVEFORM CELL DELAYED BY CELL CLOCK EDGE: TIMING VARIABLE, O AT CENTER, 1 AT EDGE OF BIT INTERVAL * Rule 1 (center transitions): A data bit sequence of “01“ always leads to a center transition in the middle of the “1“ bit.
6、 - 3404583 0089715 9T3 Page 5 EN 61120-3 : 1993 Rule 1 in HDM-1 encoding: Center transitions Data bit sequence Transition sequence of HOM-1 cells caused by “O1 “ bit sequence: Resulting HDM-1 cells waveform: Alternate HDM-1 cells waveform: . 3 I :il. . .: I- : . . e. Thus, the presence in the data b
7、it sequence of a bit pattern “01“ always enforces a center transition in the cell sequence. * Rule 2 (edge transitions): Under the three conditions defined and illustrated below and relating to specified bit sequences together with the absence of edge or center transitions in the HDM-1-coded sequenc
8、e - as indicated by the symbol (*) - an edge transition is imposed in the cell sequence. In all other cases, no transition is generated. M 3404583 0089736 83T = Page 6 EN 61120-3 : 1993 Case 1: Data bit sequence cated by (*I: “lO“, no transitions in the cell sequence at the positions indi- Data bit
9、sequence Transition sequence of HDM-1 cells caused by “10“ bit sequence in the absence of transitioais at (*): Resulting HDM-1 cells waveform: Alternate HDM-1 cells waveform: Case 2: Every data sequence indicated by (*): Data bit sequence “1 1 1 “, no transitions Transition sequence of HDM-1 caused
10、by “1 11“ bit sequence in the absence of transitions at (*): Resulting HDM-1 cells waveform: Alternate HDM-1 cells waveform: ,. . * 11 o; . .-, .i . . in the cell sequence at the positions :1 1: 1: . I . Y *Ip I i. I = 3404583 0089717 776 Page 7 EN 61120-3 : 1993 . Case 3: Data sequence “OOOO“, no t
11、ransitions in the cell sequence at the positions indica- ted by (*): . Data bit sequence . Transition sequence of HDM-1 cells caused by “0000“ bit sequence in the absence of transitions at (): Resulting HDM-1 cells waveform: Alternate HDM-1 cells waveform: o: o i o: o: ? ? IE As a consequence of the
12、 rules of HDM-1 encoding, the minimum distance between tran- sitions in a HDM-1 signal is 3 cells. The maximum distance is 9 cells, and two consecutive transition distances cannot be both equal to 9 cells. This makes it possible to use two consecutive run lengths of 9 cells as a synchronization patt
13、ern which violates the rules of HDM-1. 1.2 Signal block structure 1.2.1 The word format A word length of 16 bits and uniform quantization with twos complement and MSB leading shall be used. 1.2.2 The block structure The data on the main tracks are formatted into blocks, each block consisting of 18 w
14、ords of 16 bits. The first word in a block is called the Sync/Control word, and Is described in 1.2.3. The words 2 through 17 in a block are digital audio words and check sums, as described in 1.4.1. The last word in each block is a Cyclic Redundancy Check (CRC) word, as described in 1.4.2. The CRC
15、word serves the purpose of error detection on each track, while the check sums are used for correcting detected errors. Word 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 numbering within block Content SC We Wo We Wo We Wo Qe Qo Pe Po We Wo We Wo We Wo CRC Page 8 EN 61120-3 : 1993 4 bits SYNC = 34045
16、83 00897LB 602 16 bits 28 bits 16 bits CONTROL ADDRESS The addresses of the even and odd words (We and Wo), and even and odd check sums (Qe, Qo, Pe and Po) are detailed in 1.4.1. SC(SYNC, ADR and auxiliary data) and CRC refer to the Sync/Control word and the CRC word. As detailed in 2.1 .1, four blo
17、cks with block addresses O0 through 11 correspond to one sector on the Reference track: f-, f-, one sector PCM words We and Wo are recorded with MSB leading, and the same ordering is also valid for the check sums P and Q. The total signal block structure (included reference signal) and track formatt
18、ing are shown as follows. Channel 2 1 2 1 2 1 2 1 C I I I i S=4xb A b / 1 SYNC ADR XX X QeQo Pepo CRC 8 SYNC ADR XX X QeQo Pepo CRC 7 SYNC1 ABR IXX IX I SYNC1 ADR IXX IX I SYNC I ADR I xx I ox PCM DATA I I I I PCM DATA 3 I I I I I I I I I I I I l I I I I I I 4 Reference track I Sub-track 2 Reference
19、 track: 3404583 0089739 549 Page 9 EN 61120-3 : 1993 Legend: ADR = Block address (BA1/2) E = Emphasis (block address O0 only) Pepo E P-parity X = reserved QeQo E Q-parity . SYNC length P Auxiliary data length 8L Check data length dc Block address length a PCM DATA length dPCM CRC length c Block leng
20、th b Sector length . S = 4 x b The Sync/Control word = 11 =2 L.3 = 192 = 64 = 16 =288 r: 1152 bits bits bits bits bits bits bits bits Bit position 1 through 11 of the SyncControl word carry a synchronization pattern violating the rules of HDM-1. As the data preceding a Sync/Control word may end with
21、 an arbitrary transition distance, the synchronization pattern is defined as follows: “The synchronization pattern is characterized by two consecutive transition distances of 9 cells followed by a transition distance differing from 9 cells“. As illustrated below, the position of block begin is defin
22、ed as being 3 cells before the beginning of a synchronization pattern. Bits 12 through 16, as well as following bits until the next Sync/Control word, are coded in HDM-1. Bits 12 and 13 carry a 2-bit block address which increments by one at each new block. Bits 14 through 16 are reserved for the sto
23、rage of emphasis bits, control informa- tion, other auxiliary information, and time code markers. The value of O0 is specified for bits 14 and 15 until further definition. In blocks with block address O0 on tracks 1 , 2, 3 and 4 at speed I, bit 16 indicates whether pre-emphasis has been used. Thus,
24、a sequence O000 of bit 16 indicates that no pre-emphasis was used, and a sequence 1000 that pre-emphasis as specified in part 1 has been used. For all other tracks, a value of O is specified for bit 16 until further definition. For speed II the emphasis bit has been used on tracks 1 and 2. Page IV E
25、N 61120-3 : 1993 W 3404583 0087720 260 W Time Diagram of the Sync/Control word: block begin 4 - - - - - - -. SYNCword (16 bits) - - f- 2 bits 2 bits 1 bit emphasis flag f- + f- f-, (length 11 bits) block reserved address XX % relative to Fb C to N ratio with Sb overwriting Sa: XX dB. b) Recording an
26、d reproducing: - amplitude response at Sb relative to Sa: +X, -Y dB; - phase response at Fb as computed from response to Sc: +X -Y degrees (or: peak shift measured with Sc: +X, -Y Yo); - eye pattern measured with Sd overwriting Sa: jitter: +X, -Y Yo, - eye pattern measured with Sd overwriting Sa: op
27、ening: +X, -Y % relative to Sb amplitude; - C to N ratio with Sb overwriting Sa: +X, -Y dB. 2 Sub-track recording 2.1 Digital recording method 2.1.1 Recording method on sub-track 2 While the main track covers a digital audio signal and error detection and correction codes to protect a digital audio
28、signal, the Reference track covers a Reference signal which has independent 2,3 kbpi low-density controlling signals such as a servo control signal, so that it can ensure reliability of the machine and enrich its functions. The reference signals must be recorded on sub-track 2. 2.1.1 .l The recordin
29、g code Data on the Reference track are recorded in Biphase-Mark code. Each bit to be recorded is first mapped onto two cells. The first cell corresponding to each bit always carries a transition at its leading edge. If the bit to be encoded is a 1, the second cell carries an additional transition at
30、 its leading edge. If it is a zero, there is no additional transition at the second cells leading edge. A consequence of these generation rules is that the distance between transitions in Biphase-Mark data is either one cell, or two cells. Transition distance other than 1 or 2 cells can be used for
31、synchronization, as they violate the code rules. 3404583 0089727 615 Page 17 EN 61120-3 : 1993 SP Biphase-Mark coding rules CONTROL WORD REFERENCE ADDRESS CRC I I Data bit sequence: Resulting sequence of Biphase-Mark cells: Alternate sequence of Biphase-Mark cells: 2.1.1.2 The data format Io1 1 Il I
32、o io I Data on the Reference track are structured into Reference track words, each of them be- ginning with a synchronization pattern. Each Reference track word corresponds on the tape to so-called sector. Each Reference track consists of the following data: Synchronization pattern: (length 4 bits)
33、Control word (word length 16 bits) Reference address (word length 28 bits) A Cyclic Redundancy Check (CRC) (word length 16 bits) Word format of the Reference track word: 2.1.1.3 The synchronization pattern The synchronization patern violates the rules of Bphase-Mark by enforcing a distance between t
34、ransition of 3 cells, in connection with a well-defined signal polarity. The three consecutive cells with identical polarity are specified as being positive, Le. corresponding to a magnetization of the tape from S to N as Illustrated below. These three cells are both preceded and followed by two con
35、secutive cells of the opposite polarity. The first cell of the synchronization pattern receives a polarity depending on the previous data which ensures that the following cells will have the polarity specified above. = 3404583 0089728 551 Page 18 EN 61120-3 : 1993 The beginning of a sector is define
36、d as being three cells prior to the beginning of the 3-cell transition distance, as illustrated below: Definition of the beginning of a sector t Sector begin r- -I- +-I !I I I -I - - -+- - -1 I I I I I I II S+N: I I S+N NtS I I 2 3 2 I cells cells cells 2.1.1.4 The Control word The Control word carr
37、ies a Control word flag, information on the sampling frequency, the tape speed and other data. The control word area is defined as follows: I Ill I I I I I I-+ reserved I I I I I III I I I III I l I II I I I II I I I II I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I II- + O: cue audio u
38、nmodulated I I I I - - O: Sub-track 3 for cue audio-2 1 : cue audio modulated 1 : Sub-track 3 for auxiliary data 1- - - - - - - O: time code unmodulated I l I 1 : lime code modulated - 001: Tape Speed I 1- - - - - - - - - - l I 010: Tape Speed II I- 3 sampling frequency: 48 kHz 3 1: Tape Speed I O:
39、Tape Speed II L- 2.1.1.5 The Reference address The Reference or Sector address is a 28-bit word absolute address, representing a positive quantity in natural binary code without sign bit. The first bit of the Reference address to be recorded is its MSB. During recording, the Reference address increm
40、ents by one with each new sector. The increment rate is 1/4 the block frequency. - - 3404583 00897Z9 498 Page 19 EN 61120-3 : 1993 CONTROL WORD REFERENCE ADDRESS 2.1.1.6 The CRC word CRC The 16-bit CRC word recommended CCITT V41 is generated by the following: G(x) = x + x* + x5 + 1 with “all set to
41、1“ before CRC computation. The CRC generator is fed a sequence of 44 bits beginning with the first bit of the Control word, and ending with the last bit of the Reference address: Effective computation range of the CRC word (Reference track) -1 I I I I 1 I I 4 bits 16 bits 28 bits I 16 bits I - range
42、 of CRC word - i 2.2 Alignment of digital audio signals and sub-track signals Reference Line is assumed for the alignment of four auxiliary channels with digital audio. The auxiliary signals which link directly with the 17th word in a block with block address “00“ must be recorded on the tape with 1
43、61,5 blocks delay from the block sync to include this word. The tine is assumed as a cross line on the position of this delay. 2.2.1 Cueing signals must be aligned on the tape with the Reference Line with a tolerance of I3 blocks. Alignment of cue audio- 1 and cue audio-2 track signals 2.2.2 Alignme
44、nt of time code track signal Time code signais must be aligned on the tape with the Reference Line with a tolerance of I3 blocks. 2.2.3 Alignment of Reference track signal The edge of a sector on the Reference track and the edge of a block with block address O0 must be in geometrical alignment with
45、a tolerance of I0,5 block. 3404583 0089730 LOT Page 20 EN 61120-3 : 1993 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications This European Standard incorporates by dated or undated reference, provisions from other pu
46、blications. These noimative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revi
47、sion. For undated references the latest edition of the publication referred to applies. NUN. When the international publication has been modified by CENELEC common modifications, indicated by (mod), the relevant ENEID applies. IEC publication Date Title EN/H Date 1120-1 1120-2 1120-4 Digital audio tape recwder reel to reel system, using 6,3 rnrn magnetic tupe, for . professional use 199 1 Part 1 : Genmal yequi?*mnts EN 61120-1 1993 1991 Part 2: Fmmat A EN 61120-2 1993 1992 Payt 4: Mugnetic tupe properties: Definitions EN 61120-4 1992 and methods of meusurement
