SU1485303A1 - Method of reproducing digital frequency-modulated magnetic recording - Google Patents

Description

The invention relates to engineering

2

magnetic recording, in particular to methods of reproducing digital information recorded by the method of frequency modulation. The purpose of the invention is to increase the reliability of reproduction.

To achieve the goal, the reproduced signal is twice differentiated and there are zero transitions in each of the differentiated signals, per *. The second differentiated signal is divided into intervals between zero differences of the second differentiated signal and the number of zero transitions in each of the intervals is calculated. Depending on the counted number of zero transitions, information and synchronization signals are generated. 3 il.

The invention relates to a technique of magnetic recording, and in particular to methods of reproducing digital information recorded by the method of frequency modulation.

The purpose of the invention is to improve the accuracy of information reproduction in conditions of fluctuating carrier speed.

Fig, 1 shows the timing diagram of the signals converted according to the proposed method; FIG. 2 shows the same, but when an interfering signal is present; on fig.Z - functional diagram of the device that implements the proposed method,

Figure 1 and 2 shows the following charts:

a is an arbitrary combination of recording pulses;

£ - current drops in magnetic head 1 with dual-frequency modulation;

£> is the reproduced signal at the output of amplifier 2;

2 —differentiated reproduced signal at the output of differentiating node 3;

- twice differentiated reproduced signal at the output of differentiating node 4;

e is a sequence of pulses formed by the zero transitions of the differentiated signal at the output of node 5;

3

'1485303

four

- a sequence of pulses formed by zero ne. transients of the twice-differentiated * signal, at the output of $ 6 node;

- a dedicated information signal at the output of the trigger 7;

and - dedicated sync

signal at the output of the element ui 8.

The method is implemented as follows.

Arbitrary combination of write pulses is two-frequency modulated and 15 current drops are input into the recording head and then to the carrier “The reproduced signal is twice differentiated and the first and second pulse sequences are formed by zero transitions of the first and re-differentiation 20” which calculates the number of pulses of the second 25 sequence in the time interval concluded between the pulses of the first sequence. The counting time interval is set by setting the trigger 9 to the zero position by 39 pulses from the output of the node 5, i.e., according to the pulses of the first sequence ”which are simultaneously set to the initial position of the trigger 7.

Upon receipt of the trigger input 9 more than one pulse at the output of the trigger 9, a signal appears that flips the trigger 7, at its output a logical zero (unit) level is formed, which is fed to the bus 49 11 information signals and to the trigger 10 allowing the passage of the next pulse of the node 5 through the element And 8 on the bus 12 clock signals. . 45

On admission to the trigger input 9 of the pulse transfer trigger 9 is calculated trigger 10, but does not cause the trigger 7, after which the trigger 7 and 9 are set again to the initial position signal node 5, again following a single pulse Calculate Trigg-e ^{'g of} rum 10 and translates the latter consisting in _g · que permitting passage ochered'nogo assembly 5 pulse clock bus 12, the bus 11 data signals stored logic-one level (zero) defined by the output signal of the flip-flop 7.

When the following signals arrive, the algorithm for the synchronization and information signals is repeated.

The above combinations of the number of pulses in the counting intervals are "working", with other combinations, the reproduced signal is correlated with a reproduction failure and a reliable selection of synchronization and information signals is continued from the first newly formed logical zero (one) level in the information signal.

Claims (3)

Claim A method of reproducing a digital frequency-modulated magnetic recording, in which the reproduced signal is twice differentiated and, by zero transitions of the first and re-differentiated signals, form the first and second sequences of pulses, from which sync and information signals are distinguished, distinguished by the fact that the purpose of increasing the reliability of the reproduced information in conditions of fluctuations in the speed of the carrier, to highlight the synchronization and information signals consider chi If the number of pulses is more than one, a logical zero (one) is formed in the information signal, and at the end of the counting interval a sync pulse is formed in the synchronizing signal, with one counted pulse, the number of pulses is additionally counted in the next interval and with one pulse in the last one they form the level of a logical unit (zero) in the information signal, and at the end of the next inte the synchro pulse is formed in the synchronization signal, then the algorithm for extracting the synchronization and information signals is repeated, and for other combinations of the number of pulses in intervals, the reproduced signal is correlated with a failure five 1485303 playback and reliable synchronization and information signals continue from the first newly formed level of logical zero (one) in the information signal. I R-G ~) —I_5 _2-1) 1_0_Y ~ Y ~ 1_ ί 1_Г — 1_1-1 Г — 1 ί ^e _1_III I III III * Ι III I I III 1111 I III I I 3 — ΓΊ__ Г — I I — I 1—1 __g ~ | r — I I — 1 G — I | –1 G – 1 | –1 and — _I_1__I I_I_I I Phie.1 1485303 0 1 O O '1 7 _1 =] _ G —........ I _G — I I-1 g ~ I G ~ 1 g 3_I I I 1__1_I About 12 3 4 5 & Phi 2 Phage. δ