DE1474390C - Magnetic binary data recording with double frequency and self-synchronization - Google Patents

Description

3 4

Magnetic recording media, such as magnetic tape rectangular pulses with half the frequency of the imdern and disks, are however different phase pulses α delivers. If the impulses α and b shifts of their value impulses (bits) are not allowed to the two inputs of the AND circuit at the same time, since the sensing circuit is adjusted upwards, only the 5 clock intervals occurring at the beginning of the at least one constant phase shift are used Pulses α passed, compensated for a specific magnetic storage group as shown in pulse diagram c . The leading edge, but not several different edges, of the pulses c coincide with the beginnings of the phase shifts at different, alternating clock intervals, so that the signals c are used as magnetic recording media. Clock pulses also for other, not shown

For such modern, versatile computing systems io serve control purposes.

So the demand arises for a circuit 17 of a suitable type that works with double The clock pulses c are operated in a delay frequency and self-synchronization, z. B. delay order for the magnetic registration of binary lines, monostable breakover circuits, etc., around a data without phase shift. Delayed third of the heartbeat interval. You are as

This task of eliminating the noticeable 15 delayed pulse train c 'shown in dashed lines. These phase shifts of the binary value pulses 1 delayed clock pulses c ' are used for preliminary sensing with respect to the middle of the clock intervals to be used clock center pulse from the sengenaue clock pulse train double frequency with 20 pulse train a. The beginning of the sensing pulses c ' clock and clock center pulses generated from her z. B. therefore does not need to be strictly adhered to; By means of a bistable trigger circuit and an AND it is only important that the sensing result (the value pulse d described closing a clock pulse sequence of half the frequency) is derived in good time before (actual clock pulses) and from this start of the clock center or write pulses is available, by means of a Delay element around V3 clock 25 The binary value source used, z. B. a non-delayed pre-sensing pulses are obtained write register DR, is on the Vorden with which the binary value source z. B. sensed by the presence of a binary value 0 by sensing an AND circuit and, if the output voltage DR is present, simultaneously with the scanning of a second binary value 0, a corresponding value pulses c 'is generated at the two inputs of the AND circuit pulse that generates a extended 30 15 are supplied. If the blocking pulse is present, this allows the sampling pulse to be controlled by a binary value 0 in the register DR , and that through these blocking pulses according to F i g. 2 d as value pulse d to trigger 14 hinder the passage of the first binary value 1 through.

the clock center pulse of the clock pulse train through the trigger 14 is through the front edge of the

Another AND circuit prevented, on the other hand switched off at 35 value pulse d and then through

If the blocking pulses are not released, the leading edge of the at its second input is released

the write current controlling third bistable flip-flop effective pulse b is switched on again. At the

circle. Trigger output is therefore created with a binary value of 0

In the following, an embodiment of the er- according to FIG. 2e, a broad negative blocking pulse e in

Finding described in more detail with reference to the drawing; 40 mid-bar,

in this represents the blocking pulse e prevents with certainty the

F i g. 1 shows a block diagram of the AND circuit 16 according to the invention at the passage of a binary value 1

magnetic recording device, representing the center pulse of the pulse train a

F i g. 2 timing diagrams of the at different points to the write trigger 18.

len the circuit according to FIG. 1 prevailing pulse- 45 If, on the other hand, as in the 2nd clock interval of FIG. 2,

tensions. not a binary value 0, but 1 is present, so there is no

The circuit according to FIG. 1 contains a crystal - probably the value pulse d as well as the blocking pulse e, controlled square wave generator 11, which controls a bi- so that the AND circuit 16 apart from the constantly stable tilting circuit 12, called a trigger for short. left clock start pulse of the pulses α now an AND circuit 13 is at the outputs of the 50 also lets the clock center pulse through, as shown in FIG. 2 f triggers 12 and the generator 11 connected and shows. Thus, only single pulses / at the beginning of the clock, i.e. only device 17. The outputs of trigger 12 and one clock pulse each occur with their output at a delay switch value 0 in clock intervals a . further bistable binary value 1 double pulses / at the beginning of the clock cycle and in the breakover circuit 14. The output of these triggers 14 and 55 of the clock center, ie one clock pulse and one binary der of the generator 11 each lead to an AND switching pulse 1.

device 16, the output of which finally sends the write The leading edge of each pulse / switches the

current determining trigger 18 controls. Write trigger 18, so that this at the beginning of each

The F i g. 2 shows the time course of the in the clock interval and also in the middle of each circuit according to FIG. 1 effective voltages during ⁶ ° cycle with the binary value 1 each a reversal of the rend of several, one after the other the binary digits 0, 1, 0, writing voltage and thus also of the clock intervals T assigned by them ge-0 and 1, which are controlled by controlled magnetic Causes writing flow,
vertical dashed lines are limited. The main advantage of the above-described diagram α represents that the generator 11 in the magnetic binary data recording device stood T / 2, ie at the beginning and in the middle of each 65 is that only the clock pulse sequence a, but not the clock interval These to the transformed from it pulses b, c ', d and e, pulses α switch with their trailing edges the trigger high demands on temporal accuracy and freiger 12 continuously, so that it is made according to diagram b unity of phase shifts

have to. This is based on the fact that a very broad and therefore position-insensitive blocking pulse e is derived from the potential of the binary registration value 0 to switch off the unwanted center pulse of the pulse sequence α , which represents the binary value 1. The trigger 16 is therefore blocked in good time before the start of the mid-cycle pulse and is only canceled again after it has ended. For the passage of this pulse in cycles with the binary value 1 no time-limited passage pulse is required at all, but rather during the

During the entire cycle, there is forward potential at trigger 16.

The accuracy of the pulse train α depends directly on that of the square pulse generator 11. Different types of generator can be used depending on the level of accuracy required. However, because of its extreme accuracy with a phase shift of less than 0.01% combined with simplicity and value for money, preference is generally given to the crystal-controlled oscillator.

1 sheet of drawings

Claims (1)

1 2 Distance between two neighboring binary values, at least Claim: at least one magnetic flux reversal and optionally a second, a certain binary value, e.g. B. Magnetic binary data recording device 1 to perform flux reversal, so in with at least one regular 5 clocking with the binary value 0 only with one magnetization reversal of the recording medium, on the other hand with the value 1 with two flow reversals each Clock interval and possibly a stanchion to work. This improved magnetic Two NRZ recording mode representing a certain binary value 1 is called double frequency verten Magnetization reversal, marked by it. draws that by means of a single right 10 According to the USA. Patent 3048 831 this corner pulse generator (11) a phase-accurate regular value-independent flux reversals clock pulse sequence (α) double frequency with always in the middle between the transitions between clock and clock centers -Pulses generated, from it you can see two neighboring binary values, so in the z. B. by means of a bistable trigger circuit (12) and the middle between the clock limits or in the clock, AND circle (13) a clock pulse train (c) 15 in the middle. In those clocks in which a binary half frequency (actual clock pulses) less than 1 occurs, a short interval is passed and from this by means of a delay of the regular flux reversal in the clock center element (17) another delayed by about Va clock interval Flüß pre-sensing pulses (c ') characterizing the binary value 1 are obtained, with reversal. The ratio of this short distance to which the binary value source (DR) z. B. by means of * ° between that of the clock center and that of the binary value 1 of an AND circuit (15) and with a pre-assigned flow reversal for the absence of a second binary value 0 in the center, the result is relatively small and according to the above because of the speaking value pulse ( d) is generated, the amplitude of the resulting large difference in the sampling generation of an extended blocking pulse (e) is unfavorable. ■ by another bistable tilting circle (14) ^a 5 Therefore, z. B. in USA.-Patent 3,020,526 controls, and that through these blocking pulses (e) and in an article "High-Density Recording on Passage of the first binary value 1 - Magnetic Tape" in Electronics from October 16, the clock center pulses the clock pulse sequence (α) 1959, pp. 72 to 75, proposed, the smallest decrease prevented by a further AND circuit (16), two adjacent flux reversals were in contrast in the absence of the blocking pulses (e) free ³ ° a clock with the binary value 1 is given to half the clock width (pulse sequence /) to increase the third bistable to 1: 2, which controls the write current (9) and thus its ratio to the entire clock width. This is done by using the tilt circle (18). regular flow reversals in the value over corridors, d. H. at the clock limits, take place and the ³⁵ flux reversals dependent on the binary value 1 in the middle of the bars concerned. For this purpose, according to US Pat. No. 3,020,526, two groups of clock pulses are provided, and The present invention relates to the magnetic _ZW ar the actual clock pulses to the clock size recording, in particular of binary data on per- ⁴ ° _Z en, which constantly switch a write current generator controlling the magnetizable recording medium with the bistable trigger circuit, as well as frequency doubling and self-synchronization. the cycle center pulses, which are generated by means of an AND circle _{With the magnetic ses} working with saturation, the binary 1-values or potentials are sensed. Binary data are usually recorded _and corresponding 1-pulses are generated, which in turn a flux reversal with each data change, ie ⁴⁵ superimposed on the clock pulses _{via an OR circuit} Magnetization reversal from one and additional switchings of the bistable remanent saturation state of the recording breakover circuit and thus also of the write current in tragers into the opposite saturation state _αε 7 _Μ ϊ ^ _{η of the} relevant clocks,
without returning to the non-magnetic state ^ special the latter double frequency (Non-return-to-zero short NRZ method) In DIE _method makes it possible by ^ Si ^^^^^ S during scanning: erändert ^ '* alterations to the clock limits, for. B. in the case of several successive NuI- · * ^ei ^ ^{en Im pulse} _c ^{to iminate and} immediately as len. This yields very different time or clock pulses for synchronizing the devices spatial distances between each two aufein- ⁵⁵ to use on the receiving side. It works there other subsequent magnetizations, which means with the im ^with self-synchronization.
In the course of development, the ^{record- AHe work according to the} double frequency method- Use voltage density on the recording media to supply ^the assemblies, the two mutually separated ernehmenden difficulties in magnetic ^zeu 8 ^th clock pulse groups, in particular led Datenabfühlung. The scanning amplitudes ^{6o, in which one fluctuates due to the} delay of the other, namely depending on the distances, have the disadvantage that due to tolerances of the magnetic reversals, the greater (up to zen of the time relationship between the two pulses with an amplitude ratio of 1:30), ever the smaller the series-producing switching elements phase shift mean value of the distances, ie the larger the recordings of the value pulses compared to the exact voltage density. 65 middle between adjacent clock pulses occur In order to avoid these difficulties, it was possible. When using from one another proposed, regardless of the respective changeable, diverse and possibly even Binary value within each cycle, i. H. within the ma-