SU1332368A1 - Device for reproducing the digital information from a magnetic medium - Google Patents

Abstract

This invention relates to magnetic recording media. The purpose of the invention is to increase the accuracy of data reproduction. The device comprises a detector 1, an integrating amplifier 2, a generator 3, a trigger 4, an element J7. ; 2 5 delays, amplifier 6, voltage-interval converter 7, OR element 8, window pulse shaping bus 9, bus 10 delayed bus data 11 reproduced: pulses. The introduction of new elements and the formation of new connections between the elements of the device allows to increase the dynamic accuracy of synchronization. When the frequency of the reproduced pulses deviates from the nominal one, a phase shift of the pulses at the output of the generator 3 relative to the reproduced pulses is formed. pulse generated at the output of the converter 7 voltage-interval, 1 hp, f-crystals, 3 Il. (L U 3 -3 J 00 with ts3 with O5 00 f

Description

The invention relates to magnetic recording, in particular, to a device for reproducing digital information from magnetic media.

The purpose of the invention is to improve the fidelity of reproducing data by increasing the dynamic timing accuracy.

FIG. 1 shows a block diagram of the device; FIG. 2 is a voltage-to-voltage converter circuit of FIG. 3 - timing charts of the device.

. The device contains a phase-coupled detector 1, an integrating amplifier 2 and a voltage-controlled oscillator 3. In addition, the device contains a trigger 4, a delay element 5, an amplifier -6, a voltage-interval converter 7, an element OR 8, a pin 9 generating pulse of the detection window, delayed data bus 10, input busses of reproduced pulses -11 and reference clock pulses 12. Moreover, the output of the OR element 8 is connected to the second input of the phase detector 1 and through the delay element 5 to the first input of the converter 7 zhenie- interval. The second output of the integrating amplifier 2 is connected via the amplifier 6 to the second input of the voltage-interval converter 7. The output of the voltage-controlled generator 3 is connected to the input of the trigger 4 connected to the bus 9 to form the pulse of the detection window. The output of the voltage converter 7 The transmission interval is connected to the bus 10 of the delayed data. The input buses of the reproduced pulses 11 and the reference clock pulses 12 are connected to the first and second inputs of the SHSh 8 element, respectively.

The voltage-interval converter 7 (FIG. 2) may contain an over-resistor 13, a capacitor 14, a one-shot 15, the first terminal of the variable resistor 13 being the first input of the unit, the second signal of the variable resistor 13 being connected to its third output, to the first input and through a capacitor 14 with a second input of the one-shot 15. The third input of the one-shot 15 is the second input of the block, and the output is the output of the block.

The device works as follows.

The pulses reproduced from the magnetic carrier through the input element OR 8 (Fig. Per) arrive at

input of phase detector 1. At the output of phase detector 1 (Fig. 3b), dipulses are formed by comparing the phase of the pulses from the output of the generator 3 controlled by the voltage

(Fig. Sound), and the reproduced pulses. When the phase of the pulses of the generator 3 and the reproduced pulses coincide, the durations of the positive and negative shoulders of the dipulse coincide. In this case, at the output of the integrating amplifier 2, a steady-state voltage level is formed, corresponding to the clock frequency of the generator signal 3. Initially, the frequency

The generator 3 is tuned by a variable resistor 13 to the clock frequency of the signal, a multiple of the nominal frequency of the reproduced pulses. For example, dp case of device operation with a floppy disk drive

f 1 MHz, and the frequency of the reproduced pulses can be ../2 500 KHz, ff./ 333 kHz, 250 kHz.

When the frequency of the reproduced pulses deviates from the nominal one, for example, due to the oscillations of the velocity of the magnetic carrier, a phase shift of the pulses is formed at the output of the generator

3 relative to the reproduced pulses.

The magnitude of the shift and 1G of the leading edge of the pulses of the generator 3 relative to the reproduced them

pulses are expressed by the formula

T 27G

DG

,

Kg

where T is the pulse period of the generator 3;

LR - the deviation of the clock frequency of the reproduced pulses from the nominal;

Кф - static coefficient, transmission of the phase detector 1;

Kc, is the static transmission coefficient of the integrating amplifier 2;

Cg is the steepness of the generator 3. Accordingly, the voltage at one of the outputs of the integrating amplifier 2 (Fig. 3g) changes from I to Up + dUj, and the increment value AUp depends on the formula

iUc l

to

and

l1

where K „is the static transmission coefficient of the integrating amplifier 2 from the input to the output.

In addition, a static shift jst may occur due to a change in the device parameters from temperature and aging of elements. At the output of the amplifier 6, the voltage Ug + + 4Uc is amplified to the value U, + + Л% (Fig. Back). The reproduced pulses are delayed on the delay element 5 (Fig. Ze) by the delay value selected so that the leading edge of the delayed the reproduced pulses were shifted by an amount about the middle of the pulse of the detection window (Fig. 3), and this is determined by the maximum deviation of the clock frequency of the reproduced pulses from the nominal one.

If we choose the static gain of the control circuit; the delay I, then the increment at and m (

the duration Jf of the pulse generated at the output of the voltage-interval converter (Fig. 3) is expressed by the formula

4G

.

one

"3

Thus, the magnitude of the shift of the leading edge of the pulses of the generator 3 is compensated by the magnitude of the increment of the duration of the pulse generated at the output of the voltage-interval converter.

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Claims (2)

1. A device for reproducing digital information from magnetic media containing serially connected: element OR:, phase detector, integrator amplifier and voltage controlled oscillator, the output of which is connected to another input of the phase detector, input buses of reproduced pulses, reference signals connected respectively to the first and second inputs. of the OR element is distinguished by the fact that, in order to increase the accuracy of data reproduction by increasing the dynamic synchronization accuracy, the delayed data bus and the pulse shaping bus of the detection window, the delay element, trigger, input of which is connected to the generator output, control voltage and the output to the pulse shaping bus of the detection window, a series-connected amplifier and a voltage-interval converter whose output is connected to the delayed data bus, and another stroke transducer-voltage range is connected via a delay element to the output OR gate. , 2. The device according to claim 1, wherein the voltage-spacing converter contains a variable resistor, a capacitor and a single-oscillator, the output of which is the voltage spacing converter output, the first output of the variable resistor being the first input of the converter, and the second output connected to the third output, to the first input of the single vibrator and through a capacitor to the second input of the single vibrator, the third input of which is the second input of the voltage-interval converter. Bxodi 13 GT i-HI- Vm9g Compiled by N.Vikhrova Editor V.Petrai Techred M.Dvdyk Proofreader L. Pilipenko Order 3838/47 Circulation 589 Subscription VNIIPI USSR State Committee for inventions and discoveries t13035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 : YAS Tl Output :WITH /five FIG. g Fig.Z