1、CEN ENa28630-3 92 m 3404589 0035837 980 = EUROPALSCHE NORM EN 286303 August 1992 UDC 81.327.63 Descriptors: Data processing, information interchange, data recording devices, magnetic disks, flexible disks, flexible disk cartridges, recording tracks, trackformat, specifications English version Inform
2、ation processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 13 262 ftprad, on 80 traks each side Part 3. Track format B for 80 tracks (IS0 86303 : 1987) Traitement de linformation - change de donnes sur cartouches disquettes de 13
3、0 mm (5,25 in) utilisant un enregistrement moddation de frquence modifie (MFIVI) 13 262 ftprad sur 80 pistes sur chaque face Partie 3. Schma de piste B pour 80 pictes Informationsverarbeitung - Datenaustausch auf 130 mm (5,25 in) Disketten mit modifizierter Wechseltaktschdt bei zweiseitiger Aufzeich
4、nung mit 13 262 FlusswechseVrad und 80 Spuren auf jeder Seite Teil 3. Spurformat B fr 80 Spuren (iSO8630-3: 1987) (IS0 8630-3 : 1987) This European Standard was approved by CEN on 1992-0 b) a flux transition shall be written at each cell boundary between consecutive bit cells containing ZEROS. Excep
5、tions to this are defined in 4.12. 4.2 Track location tolerance of the recorded flexible disk cartridge The centrelines of the recorded tracks shall be within t 0,042 5 mm ( + 0.001 67 in) of the nominal positions, over the range of operating environment specified in IS0 8630-1. CEN ENx28630-3 92 34
6、04589 0035820 475 80 /o to I 20 /o 130% to 16So/o - BS 6957 : Part 3 : 1988 130% to 165% 18S0/0 to 225% c- / 4.3 Recording offset angle At the instant of writing or reading a magnetic transition, the transition shall have an angle of Oo k 18 with the radius. NOTE - As tracks may be written and overw
7、ritten at extremes of the tolerances given in 4.2 and 4.3, a band of old information may be left at one edge of the newly written data and would constitute unwanted noise when reading. It is therefore necessary to trim the edges of the tracks by erasure after writing. 4.4 Density of recording 4.4.1
8、The nominal density of recording shall be 13 262 ftprad. The resulting nominal bit cell length is 75,5 prad. 4.4.2 The long-term average bit cell length shall be the average bit cell length measured over a sector. It shall be within f 3.0 % of the nominal bit cell length. 4.4.3 The short-term averag
9、e bit cell length, referred to a par- ticular bit cell, shall be the average of the lengths of the preceding eight bit cells. It shall be within f 8 % of the long- term average bit cell length. 4.5 Flux transition spacing (see figure 1) The instantaneous spacing between flux transitions may be influ
10、enced by the reading and writing process, the bit sequence recorded (pulse crowding effects) and other factors. The locations of the transitions are defined as the locations of the peaks in the signal when reading. Tests should be carried out using a peak-sensing read amplifier (see annexes 6 and C)
11、. 4.5.1 The spacing between the flux ?ransitions in a sequence of ONES shall be between 80 % and 120 % of the short-term average bit cell length. 4.5.2 The spacing between the flux transition for a ONE and that between two ZER:ution of 55 % to 65 A at track 76 on side O and at track 68 on side 1, us
12、ing the reference material RM 8630, applying the calisiation factor of the reference material, and recording with the appropriate test recording current The resonant frequency of the head shall be at least 500 O00 Hz. The resolution shall not be adjusted by varying the load impedance of the head The
13、 resolution shall be measured at the output of the amplifier defined in 8.3.3.1. 6.3.2.2 Offset angle The head shall have a gap offset angle of Oo k 6 with the disk radius on the testing drive. 8.3.2.3 Contact Care shall be taken that the heads are in good contact with the media during the tests. 6.
14、3.3 Read channel 6.3.3.1 Read amplifier The read amplifier shall have a fiat response from 1 o00 to 375 O00 Hz within ? 1 dB, and amphde saturation shall not occur. 6.3.3.2 Peak sensing amplifier Peak sensing shall be carried out by a differentiating and limiting amplifier 6 CEN EN*28630-3 72 m 3404
15、589 0035825 T57 m BS 6957 : Part 3 : 1988 B.3.4 Time interval measuring equipment The time interval counter shall be able to measure 2 ps to at least 5 ns resolution. A triggering oscilloscope may be used for this purpose. 1 B.4 Procedure for measurement B.4.1 Flux transition spacing measurement The
16、 transition locations shall be measured by the locations of the peaks in the signal when reading. The flux transition spacing shall be measured by the pulse timing intervals after the read channel amplifier defined in 8.3.3. 8.4.2 Flux transition spacing for all tracks Measure time intervals tl to t
17、5 as shown in figure 5. .A, . 7 11 o1 I o1 11 1 o1 11 O01 I I tl and t2 correspond to sub-clause 4.5.1 t3 and t4 correspond to sub-clause 4.5.2 t5 corresponds to sub-clause 4.5.3 Figure 5 CEN EN*k28630-3 92 3404589 0035826 993 I BS 6957 : Part 3 : 1988 Annex C Data separators for decoding MFM record
18、ing (This annex does not form part of the standard.) c.1 On track 00, side O the two-frequency recording results in nominal flux transition periods of I for a ONE cell 21 for a ZERO cell where I = 2 ps. The data separator shall be capable of resolving a difference of 2 )IS. This can be achieved sati
19、sfactorily by the use of a digital da separator, or one using a fixed timer. c.2 On all other tracks the MFM recording method gives nominal flux transition spacings of I for the patterns 11 or O00 3/2 for the patterns 10 or O1 21 for the pattern 101 The data separator should be capable of resolving
20、a difference of 1 ps. To achieve this with a low error rate, the separator cann operate on a fixed perin! Sut should fdlow changes in the bit cell length. It is recognized that various techniques may be developed to achieve dynamic data separation; with present technology only i analogue data separator based on a phase-locked oscillator can provide the necessary reliability.
