SU1046764A2 - Device for reproducing digital data signals from magnetic record medium - Google Patents

Abstract

DEVICE FOR REPRODUCTION OF DIGITAL INFORMATION SIGNALS FROM MEDIA MAGNET RECORDING on author.St. No. 920825, characterized in that, in order to reduce the reproduction error of anti-transverse markers, a sequentially connected controlled generator, a first counter, a first decoder and a counting trigger, successively connected second counter, a second decoder, a third counter with a variable division factor and a second are entered into it. additional pulse shaper, as well as the first and second additional elements And, additional trigger, control bus and additional output bus devices, while the input the controllable hexagon, the installation inputs of the counting trigger and the second counter are connected to the first output of the demodulator sync pulses, the various inputs of the first additional element I are connected to the output of the counting trigger and to the control bus, its output to the installation input of the additional trigger, the reset input of which is connected to the output of the second additional pulse former, and the output (A is connected to one input of the second additional element I, the other of which is connected to the output of the additional element This And, another 1 with the input of which is connected to the output of the additional pulse generator and the input of the second counting trigger: Gera, and the output is connected to the additional output bus of the device. 4 O) a

Description

The invention relates to magnetic recording, in particular, to devices for reproducing digital information signals from a magnetic recording medium. According to the main auth. H ° 920825, a device for reproducing digital information signals is known. magnetic recording medium containing a reproducing head connected through an amplifier to a filter input, the output of which is connected to the first of the inputs of a signal replacement unit connected by the first of the outputs to the first of the input of a double frequency driver, and to the input of a pulse shaper connected by the output with the second input of the signal replacement unit and with the first input of the detection unit, the first and second outputs of which are connected to the first and second of the output buses, and the second input to the first and second outputs The output of the demodulator sync, pulses connected by the input to the second output of the replacement si nals unit, the third input of which is connected to the output of the double frequency generator, the first element I – j connected to the first input of the detecting unit, a series connected element NOT connected to the second the demodulator of the clock pulses, the second And element connected to the second output of the signal replacement unit, and the third And element connected in series with the multivibrator connected to the first output of the blue demodulator pulses, and an additional pulse generator, connected by a V "output to the fourth output bus, included in series the first differentiating element and the first trigger, the first output of which is connected to the fourth input of the substitution unit and the second output to the second input of the doubler the frequencies connected in series the second trigger, the fourth element And and the second differentiating element, connected in series the first element And connected to the third output of the signal replacement unit, and OR connected to the output of the fifth output bus, the input of the fifth AND element: connected to the second trigger, one input of which is connected to the output of the additional driver with 1 pulses connected to the input of the first differentiating element, the second input connected to the input of the fourth element And, and the output of the second differentiating element connected to the first trigger, the second, the output of which is connected to the input of the third element And and to the input of the first element And connected to the input element and OR t1. A disadvantage of the known device is a significant reproduction error due to low noise immunity when detecting anti-transposable markers. Indeed, stable detection of information symbols 1 takes place in the recognition region ± f / k, where T is the period of the clock pulses, and the detection of these clock pulses occurs in the region from up to 5 / M. However, in the latter case, the pulses of the anti-transverse marker begin to be detected, which outside the zone are false. Consequently, when detecting information symbols, synchronization pulses and anti-transverse markers in a known device, the amount of resistance is different and directly depends on the size of the signal recognition area, and even without taking into account temporal distortions, the distortion of reproducible signals more strongly affects the noise immunity of synchronization pulses and an anti-transverse marker in the region of the latter’s detection zone than outside this zone. The purpose of the invention is to reduce the error in reproducing anti-skew markers. The goal is achieved by introducing a serially connected controlled oscillator, a first counter, a first decoder and a counting trigger, a second counter connected in series, a second decoder, a third counter with a variable division factor, and a second additional pulse shaper into a device for playing digital information signals from a magnetic recording medium. , and tayuhe first and second additional elements And, additional trigger, control bus and additional output bus device The input of the controlled oscillator, the installation inputs of the counting trigger and the second counter are connected to the first output of the demodulator of the sync pulses, the different inputs of the first auxiliary element I are connected to the output of the delay element of the detecting unit and the output of the counting trigger and to the control bus, its output to the installation an additional trigger input, the reset input of which is connected to the output of the second additional pulse generator, and the output is connected to one input of the second additional element AND, the other the input of which is connected to the output of an additional element I, the other input of which is connected to the output of the additional forcing pulses and the input of the second counting trigger, and the output is connected to the additional output bus of the device. In order to increase the noise immunity of the detected signals, blocks have been introduced that eliminate the possibility of left-handedly no spurious pulses of the anti-transverse marker outside its zone; the intervals of following correct synchronization pulses are determined in zones of anti-transverse markers and the sign of unreliability of synchronization pulses in these zones provide the minimum required number of impulses of anti-transverse marker, which is strictly related to the magnitude of the synchronization pulses. . As a result, the synchronization pulses have a fairly high fidelity and there is no need to re-install the compensation device. FIG. 1 shows the functionality of the proposed device; in Fig. 2 - timing diagrams illustrating the operation of the device. A device for reproducing digital information signals from a magnetic recording media gel contains a reproducing head 1 connected via an amplifier 2 to an input of a filter 3. An output of a filter 3 is connected to the first input C of the replacement signal block 5 connected by the first output 6 to the first input of the former 7 twice frequency, and to the input of the pulse driver 8,. The output of the driver 8 is connected to the second input 9 of the signal replacement unit 5 and to the first input 1 of the detection unit 11, the first and second outputs of which are connected respectively to The second and second output buses 12 and 13, and the second input co6k are united with the first output of the demodulator of 15 sync pulses. The first output 14 of the demodulator .15 is connected to the third output bus 16, and its input is connected to the second output 17 of the signal replacement unit 5, the Third input 18 of which is connected to the output of the driver. 7 doubled frequency. The device also contains the first element AND 19, connected to the first output of the detection unit 11 and a series-connected element NOT 20, connected to the second output 21 of the demodulator 15 of the sync pulse B second element 22, connected to the second output 17 of the replacement block 5 of the signals, and the third element And 23. In addition, the device contains connected in series an improved multivibrator 2 connected to the first output H of the demodulator of 15 sync pulses, and an additional driver of 25 pulses, the fourth output bus 26, included Consequently, the first differentiating element 27 and the first trigger 28, the first output of which is connected to the fourth input 29 of the signal replacement unit 5, and the second output to the second input 30 of the double frequency generator 7, connected in series the second trigger 31, the fourth And 32 element, the second differentiating element 33 and the fifth element AND 3 connected in series and the element OR 35 connected by an output to the fifth output bus 36. Herewith the fifth element AND 3 is connected to the third output 37 of the signal replacement unit 5. In the proposed device, the second input of the fifth element And 3 is connected to the second trigger 31, one input of which is connected to the output of the additional imaging unit 25 pulses connected to the input of the first differentiating element 27, and the other input to the output of the third element And 23,. Connected to the input of the fourth element AND 32. At the same time, the output of the second differentiating element 33 is connected to the second input of the first trigger 28, the second output of which is connected to the input of the third element and to the input of the first element AND 19 connected to the second input of the OR element .35. Replacement block 5 and signals consists of elements I Sv-, summing triggers and AZ, Schmidt trigger l. S1 rectifier 5 shaper 6 pulses and element OR i. The first input 4 of the block 5 of replacing the signals coincides with the input of the rectifier kS, the output of which is connected to the inputs of the Schmidt trigger and pulse shaper. The output of the pulse generator 6, coincident with the third output 37 of the signal replacement unit 5, is connected to the inputs of elements 38 and 39, the other inputs of which are connected to the outputs of the Schmidt trigger t, and the outputs to the inputs of summing trigger 42. The first output of the summing trigger 42 is connected to the first input of the summing trigger 3, and the second output to the first input of the element AND lO, the second input of which coincides with the second input 9 of the replacement unit 5 and signals. The output of the element 40 is connected to the second input of the summing trigger 43, the output of which coincides with the first, output 6. The signal replacement unit 5 is connected to the first input of the element AND 41 whose second input is connected to the output of the pulse maker 46, and the third input coincides with the fourth input 29 of the signal replacement unit 5 The output of the AND element 41 is connected to the first input of the OR element 47, the second input of which matches with the third input house 18 of the replacement unit 5 and signals, and the output is. with the second exit 17 last. The dual frequency shaper consists of differentiating elements 48-50, elements OR 51 and 52, And 53 and 54 elements, waiting for multivibrators 55 and 5b. The first input of the double frequency Shaper 7 coincides with the first input of the And 53 element and 54, and with the input of the differentiating element 48, the output of which is connected to the first input of the OR 51 element. The second input of the OR element 51 is connected to the AND 53 element and the output to the input of the waiting multivibrator 55 whose output is connected through the multivibrator 56 to the input differentiating element 49, and the first differential element 50 — with the first input of the element OR 52. The output of differentiating element 49 is connected to the second input of the element AND 53 and the second, the input of the element OR 52. The output of the element OR 52 is connected to the second input of the element AND 54 The third input and output 4 of which coincide with the second input 30 and the output of the double frequency generator 7, respectively. Detection block 11 consists of a delay element 57, a counting trigger 58 and And 59 and 60 elements, and a demodulator of 15 sync pulses - from waiting multivibrators 61 and 62 and an element 63. The first input 10 of the detecting block 11 coincides with the counting three input: - Ger 5B and its second input is with the input of the delay element 57 and with the first inputs of the And 59 and 60 elements. The other input of the counting trigger 58 is connected to the output of the delay element 57, and the output to the second inputs of the And 9 and 60 elements whose outputs coincide with the first and the second outputs of the detection unit 11. The input of the demodulator of the 15 sync pulses coincides with the first input of the element And 63, the second input of which is connected to the output of the waiting multivibrator 61. The outputs of the element 63 and the waiting multivibrator 61 coincide respectively with the first output 14 and the second output 21 of the demodulator 15 of the sync pulses. The output element And 63 is connected through a standby multivibrator 62 to the input of a standby multivibrator 61. In addition, the device is equipped with a series-connected controlled generator 64, first counter 65, first decoder 66, counting trigger 67, first additional element And 68, additional trigger 69, the second additional element And 70, the other input of which is connected to the output of the additional generator 25 and serially connected by the second counter 71, the second decoder 72, the third counter 73 with variable dividing factor m, the second additional pulse generator 74 whose output is connected to the reset input of additional -triggera B9, and the control bus 75 and an additional output line 7b device. I In this case, the control input of the generator 64, the installation, the inputs of the counting trigger 67 and the second counter 71 are connected to the first output 14 of the demodulator T5 clock pulses, the inputs of the first additional element And 68 are connected to the output of the delay element 57 of the detection unit 11, to the output of the counting trigger B7 and control bus 75, its output - to the installation input of an additional trigger 69, the reset input of which is connected to the output of the second additional driver 7, and the output is connected to one input of the second additional element And 70, the OTHER input of which is connected to the output of the additional imaging unit 25 pulses and the input of the second counting trigger 71, and the output is connected to the additional output bus 76 of the device. The device works as follows. The signal reproduced by the magnetic head 1 after the amplifier 2 and the filter 3 hits the driver in which it is converted into a sequence of pulses. On the demodulator 15 sync pulses, the signal previously converted in blocks 5 of replacement and 7 of formation of double frequency gets, therefore in this signal no changes due to a decrease in the amplitude of the reproduced signal. This is achieved by the fact that the signal from the filter 3 passes through the rectifier +5 and then gets formed by the extremum in the shaper 6 and processed in the Schmidt trigger A. As a result, there are sequences of pulses, which are used to obtain a pulse corresponding to the deposition mode. Formation of the beginning and end of the fallout region is carried out using the elements 38 and 39 and trigger 2 and already in the trigger a pulse corresponding to the fallout mode is formed into a replacement pulse. To obtain anti-transverse markers from digital information recorded on magnetic media (Fig. 2a Detected sync pulses are applied to the waiting multiple 2k vibrator from the AND 63 demodulator element of the 15 sync pulses and the output bus 16 (Fig. 2b). With the former 25, the formed anti-skew marker (Figo 2b1 enters the differential). The prioritized chain 27 (Fig. 2rJ, the formed back fronts of which establish the trigger 28, from the output of which the leading fronts of the additional fall are formed. The inverted and non-inverted additional fallout signals (.fig. 2e) simultaneously arrive responsibly at the elements And And 5 of the blocks 5 and 7 replacing the signals and forming the double frequency, and Rae deciding the passage of the detected pulse sequence from the And 23 element to the trigger 31 (Fig. 2e, g ;, with the help of which, And the element 32 and differentiating epochki 33 form pulses reset flip-flop 28 (FIG. 2h). The permissive resolution signals generated by the extremum from the imager 6 of the substitution block 5 of the signals are transmitted through the AND 3 element to the output element OR 35. I After the arrival of the reset pulses to the trigger 28, an additional fallout zone is formed at the output. At the first input of the output element OR 35, the detected information is transmitted through the element AND 19 outside the zone of additional fallout from the output of the element 59 of the detection unit 11, and then the total signal of the detected information enters the output bus 36 (Fig. 2k, l, m), and the output bus 16 receives restored 1; 1E synchronization pulses f (Fig. 2n). Further work of the proposed device is as follows. The additional trigger 69 through the additional first element AND 68 is preset to the initial state by the control signal received from the control bus 75, which allows the output of the detected anti-transverse markers to be output. At the same time, the pulses of the anti-skip marker arrive at the input of the second counter 71 and, after the second decoder 72 and the third c-reader 73, with a variable division factor, are fed through the second additional driver 7 to reset the additional trigger b9. From the output of the latter, a signal to prohibit the passage of anti-skew markers to the additional output bus 76 is formed. The division ratio of the third counter 73 is selected depending on the desired fidelity of reproduction. At the same time, using a controlled generator b, the first counter b5, the first decoder 66, the counting trigger 67 and the first additional element I 68, the presence of pulses is constantly monitored

shifted by half of the period relative to the demodulated sync pulses of the sequence. If in the period of the demodulated sync pulses of the search vehicle or there are no two pulses of the shifted sequence, then from the first additional element. And 68 to the installation input of the trigger 69 receives a developed pulse Error and trigger b9 allows the passage of anti-transverse markers through the second additional element AND 70 to the additional output bus 76. Thus, a series of anti-transverse markers are formed at the device output, eliminating the formation of spurious pulses, thereby reducing reproduction error of anti-crossbar markers.

In the proposed device, the number of reliable synchronization pulses is placed within the period of the pulse of the anti-transverse marker, and then

and counting the number of reliable marker pulses (the pulses do not pass to the third counter 73), and a prohibiting signal for the passage of the anti-skew marker pulses to the additional output bus 76 is generated, where they are transmitted in strictly limited quantities.

The introduction of additional blocks into a known device allows one to increase the fidelity of the reproduced information by excluding the anti-transverse marker pulses outside the zone of their detection and forming the sign of unreliability of synchronization pulses inside this zone.

The proposed device allows sampling of virtually any temporal mismatch, digital information across the width of the magnetic tape, which ultimately reduces the information reproduction error by a factor of 2-3.

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Claims (1)

: DEVICE FOR PLAYING DIGITAL INFORMATION SIGNALS FROM A MAGNETIC RECORDING MEDIA by ed. No. 920825, it is noteworthy that, in order to reduce the error in the reproduction of anti-skew markers, a sequentially connected controlled generator, a first counter, a first decoder and a counting trigger, a second counter connected in series, a second a decoder, a third counter with a variable division coefficient and a second additional pulse shaper, as well as the first and second additional elements And, an additional trigger, a control bus and an additional output device bus ^, while the input is of the inventive generator, the installation inputs of the counting trigger and the second counter are connected to the first output of the demodulator 'clock pulses, the different inputs of the first additional element And are connected to the output of the counting trigger and to the control bus, its output is connected to the installation input of the additional trigger, the reset input of which is connected with the output of the second additional pulse shaper, and the output is connected to one input of the second additional element And, the other input of which is connected to the output of the additional element And, dr goy one input of which is connected to the output of the pulse and the additional input of the second counting flip-flop, and an output connected to an additional output device bus.