SU1413667A2 - Apparatus for detecting signals of digital information in reproduction from magnetic record carrier - Google Patents

Abstract

The invention relates to the field of magnetic records. The purpose of the invention is to reduce the detection error by correcting the information at one-bit signal drops. At the inputs of the element And 7 there are signals from the outputs of the trigger 6, the trigger 8 and the pulses of the third sequence. When these signals coincide at the output of the element And 7, pulses are formed, which set the counting trigger 10 into one state, which generates the clock pulses fed to the bus 16 and to one of the inputs of the element 14, and the second input of which receives the pulses of the third sequence. When these signals coincide, output pulses of information element 14 form 1. Information pulses 1. At inputs of element 21, there are pulses from the output of flip-flop 24, information pulses 1 and NO 23 inverted impulses from an element. When they coincide at the output of the element And 21, pulses are formed corresponding to single impulses of pulses 1, which are summed on the element OR 20 with the delayed element 19 for a period of sync pulses of information pulses 1. 2 Il. i (L

Description

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The invention relates to magnetic recording, in particular, to devices for detecting digital information signals during reproduction from a magnetic recording carrier.

The aim of the invention is to reduce the detection error by correcting the information in one f; bit dropout of the signal. FIG. I shows the functional scheme of the proposed device; FIG.

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Temporary diagrams for exploring how it works.

A device for detecting digital information signals during reproduction from a magnetic recording medium: contains a playback unit 1 connected by an output to the inputs of a generator (2 pulses by extremes (Signal and a 3 pulse generator; by signal levels, connected by outputs correspondingly with the first and second inputs of the first element I A and; with synchronization and informational inputs of the first trigger 5, CWDs- | Dynennogo output to the setup input of the second trigger 6, the output of which The second element And 7 connected; the second input to the output of the third trigger 8, the clock input of which is connected to the output of the decoder 9 connected to the clock inputs of the second trigger 6 and the first and second counting triggers 10 and 11. The device also includes a generator of 12 pulses connected by the output with the synchronization input of the counter 13, connected by the output to the input of the decoder 9 and the installation input - to the output of the first element AND 4 connected to the third input of the second element AND 7, with the installation input of the second counter th trigger 1 1 and with the first input of the third element And 14 connected by the second input to the output of the first counting trigger 10. In addition, the device contains output information and synchronization buses 15 and 16, with the first counting trigger 10 connected to the output bus 16, the third counting trigger 17 connected by a sync input. to the output of the second counting trigger 11 and connected by the setup input to the output of the first element I 4, the fourth element I 18, connected by the output to the information input of the third trigger 8 and the connected first number 1 and the second inputs to the outputs of the second and third counting triggers 1 and 17, the delay element 19, the OR element 20, the fifth and sixth elements And 21 and 22, the NOT element 23, the fourth and fifth triggers 24 and 25. The element 14 is connected to the bus 15, through the series-connected delay element 19 and the element OR 20. Element OR 20 is connected From the inputs to the output of the first element I 21, the first input of which is through the element NOT 23 is connected to the output of the second trigger 6, the second input is connected to the output of the third element 14 and the third input is connected to the output of the fourth trigger 24 connected by a synchronization input to the output of the decoder 9 and information input with the output of the sixth element I 22 connected by the first input to the output of the fifth trigger 25 connected by the synchronization input to the second input of the element K 22 connected to each other and the output of the fourth element I 18 and the mouth new input to the output of the first element And 4.

The device works as follows.

FIG. 2a shows the current recording signal corresponding to the coding method of the original information (Miller's move). The reproduced, amplified and filtered signal (FIG. 26) from the output of the playback unit 1 enters the shaper 2 and 3 pulses at extremes and fixed levels, respectively. During operation, the device generates a series of pulse sequences. Shaper 2 performs the formation of the first pulse sequence (Fig. 2c) at the extreme points of the signal, and Shaper 3 - the second pulse sequence (Fig. 2d) at fixed signal levels. Trigger 5 generates them- corresponding to the occurrence of the signal-output mode (Fig. 2d), the duration of which is equal to the interval between the first extremes after the beginning and the end of the loss mode. Element 4 at the moments of coincidence of the first and second sequences forms the third pulse sequence ( 2e), the pulses of which zero the counter 13. The counter 13 performs the counting of the high frequency pulses of the oscillator 12. The frequency of the oscillator 12 and the coefficient of recalculation of the counter 13 are chosen so that the output of the decoder 9 is delayed in a quarter of the sync pulse period relative to the third sequence, a fourth pulse sequence (fig. 2g) of the doubled clock frequency is formed. The third sequence pulses also trigger triggers 11 and 17. Trigger 11 switches on each pulse (Fig. 2h) of the fourth sequence, and trigger 17 on each differential from high level to low (Fig. 2i) / signal from the trigger output 11. In as a result, at the output of the element I I8, pulses are formed (Fig. 2k), which for each pulse of the fourth sequence are memorized in trigger 8 (Fig. 2n),

At the same time, the pulses from the output of trigger 5 nullify trigger 6, which maintains a low potential at the output until the first pulse of the fourth sequence after the end of the pulse of the fourth sequence sets a high potential at the output of trigger 6 (Fig. 2m). Thus, at the outputs of the element 7 there is a signal from the outputs of the trigger 6 (Fig. 2m), the trigger 8 (Fig. 2l) and the pulses of the third sequence (Fig. 2e). When these signals coincide at the output of the element And 7 pulses are generated (Fig. 2n), which set the counting trigger 10 into one state. The trigger 10 switches over each pulse of the fourth sequence and generates the sync pulses (Fig. 2o) fed to the bus 16 and to one from the inputs of the element 14, the second input of which receives the pulses of the third sequence (fig.2e). When these signals coincide at the output of the element 14, information pulses 1 are formed.

At the same time, the third sequence pulses set the trigger 25 to one state. The trigger 25 maintains a high potential output, as long as the difference from the high level TO LOW of the first pulse from the output of the AND 18 element

will set a low potential at the output of the trigger 25 (Fig. 2p). As a result, the output of the And 22 element is passed (Fig. 2c), the first after the pulses of the third sequence, the pulses from the output of the And 18 element, which are recorded by the pulses of the fourth sequence in the trigger 24 (Fig. 2t),

Thus, at the inputs of element 21 there are pulses from the output of trigger 24 (fig. 2t) pulses of information 1 (fig. 2p) and inverted pulses inverted by the element NOT 23, if they coincide, the output signals of element i 21, pulses are formed (Fig. 2f), corresponding to single impulses of pulses 1, which are added on the OR element 20 with the delayed delay element 19 for the period of the clock pulses of the information pulses 1 and are fed to the bus 15.

Claims (1)

Invention Formula A device for detecting digital information signals during reproduction from a magnetic recording medium according to the author. St. No. 1278944, characterized in that, in order to reduce the detection error by correcting information during one-bit signal drops, the delay elements, the OR element, the fifth and sixth AND elements, the NOT element and the fourth and fifth fifth triggers are introduced into it, the third element AND the connection to the output information bus through the series-connected delay element and the OR element, connected by one of the inputs to the output of the fifth AND element connected by the first input through the element NOT to the output the second trigger, the second input with the output of the third element I and the third input with the output of the fourth trigger connected by the synchronization input to the output of the decoder and the information input to the output of the sixth element And connected by the first input to the output of the fifth trigger connected by the synchronization input to the output fourth element 55 , - that And the second input of the fifth element And and the installation input - with the output of the first element I. i I I I e L J l LLL, LL (M 1 I I I I I I I I I I 1 I I I I I I I 3 JPJPJPJPJnLP, .LrlJPJ n Jt n t {/ f n TT n n Editor M. Pandora 2 Compiled by V. Dobrovolsky Tehred A. Kravchuk Proofreader L. Patay „I I I I one I1 I JTL GT L n n n