SU758243A1 - Device for reproducing information from magnetic carrier - Google Patents

Description

The invention relates to the instrument. structure and is intended for use in storage devices of computers on magnetic tapes, disks and drums.

A device for reproducing information from a magnetic carrier of a phase-modulated signal is known, which makes it possible to isolate sync pulses using a mono-vibrator 'and does not allow sync pulses to be recovered when signals fall out that occur with defects in magnetic media, which reduces the noise immunity of the device (1). one

The closest in technical essence to the present invention is a device for reproducing "digital information from a magnetic carrier, comprising a first trigger, 2 output buses of code and synchronizing pulses, an input bus connected via a zero-organ with two logical elements And, a pulse generator connected to counter * through the third logical element And, the pulse shaper connected to the second trigger [2].

The disadvantage of this device is low noise immunity caused by 3

2

following factors. Single fallouts of the signal lead to large fluctuations of the period of the sync pulses, and non-uniformity of movement of the magnetic carrier leads to detection errors. When using a known device for reproducing information recorded by the UFMP method, a reliable selection of sync pulses and coding pulses is not ensured due to the peculiarities of this method.

The aim of the invention is to improve the noise immunity.

For this, the proposed device is. The device is equipped with a monovibrator and a decoder, while the counter outputs are connected to the decoder inputs, one decoder output is connected to the second trigger input directly, and the code pulse and the first logic element I, the second output of the decoder is connected to the output bus of synchronizing pulses and the third logic element the output of the decoder is connected to the input of the zero setting of the counter, the output of the monovibrator is connected to the input of the driver

• pulses, the output of the second trigger

ι; connected to the zero input

3

counter through the 'second' element And, and the output of the zero-organ is connected to the third element And through the first trigger. '

FIG. 1 shows a block diagram of the proposed device; in fig. 2 time diagrams of his work.

Input bus 1 devices? through the 'null-organ' 2 is connected to the logical elements I 3 and 4 and the first trigger 5. The output of the first trigger 5 through the logic element 6, the other input of which is connected to the output of the pulse generator 7, is connected to the counting input of the counter 8. The outputs of the counter 8 connected to the inputs of the decoder 9. One output of the decoder 9 is connected to one input of the second trigger 10 directly, and to the other via a monovibrator 11 and pulse generator 12, the output of the second trigger "" 4, the output connected to by entrance The zero setting of the counter 8, the output of the monitors, c is connected to the second input of the logic element And 3, the output connected to the output bus 13 code pulses. The second and third outputs of the decoder 'are connected respectively to the output bus 14 clock pulses' and the zero input of the counter 8.

The device works as follows.

Acting from the zero level of the signal coming through the input bus 1 (see Fig. 2, a), the zero-body 2 produces pulses (see Fig. 2, b), which are fed to one input of logic elements 3 and 4 and a single trigger input 5. The first pulse sets the trigger 5 to a single state, and a high potential at its output opens the AND 6 logic element. The pulses from the output of the pulse generator 7 (see FIG. 2, c) through the logical '. AND 6 element arrive at . counter count input 8.

When the counter code 8 (see Fig. 2, g) reaches the value corresponding to 1/4 of the clock frequency, the decoder 9 produces a pulse (see FIG. 2, d), which starts the monovibrator 11. The monovibrator produces a pulse with a duration of 1/2. clock period "(see Fig. 2, e), which is fed to the 'one input of the logic' element 3. Therefore, through the logic element IZ to the output bus 13 'of the code impulses ..

The impulses pass from the output of the nullorgan 2, developed in the middle, of tact, which. corresponds to the unit code. When the counter code 8 reaches a value corresponding to 1/2 of the clock frequency, the decoder 9 generates an impulse that goes to the output bus 14 of the clock pulses (see, Fig. 2, h). Pry ACHIE- * zhenii code · counter 8 values of the clock frequency decoder 9 9υρΗβθίΗ758243 d

impulse, which puts the counter 8 in the zero state. Pulse generator 12 of the trailing edge 11 monovibratora pulse produces a pulse (see. FIG. 2, u), which s.tas ^ve T flip-flop 10 in the set condition (see. FIGS. 2, k).

Trigger 10 is put into zero state by impedance from the output of the decoder, when the counter code corresponds to ^ 0 em 1/4 of the clock frequency. A high potential at the single output of the trigger 10 opens the logical element I 4. If during a high-potential at the output of the trigger 10 the zero-body generates a pulse, then it passes through the logical element I 3 (see Fig. 2, l) and installs counter • 8 to zero. The latter circumstance makes it possible to correct the beginning of the reference period in accordance with the uneven movement of the magnetic carrier.

. · /

The device allows you to select clock pulses with a clock frequency of 25 for any fallout of signals. In addition, the device is insensitive to fluctuations in the speed of movement of the magnetic carrier, since the starting point of the pulse cycle is corrected in accordance with the reproduced signal.

Claims (1)

Claim A device for reproducing digital information from magnetic media containing the first trigger, output coded code buses and synchronizing 4.0 impulses, input bus, ₄ connected 'Perez zero-organ with two logical elements And, a pulse generator connected to the counter via the third logical 45' element.I, a pulse shaper connected to the second trigger, which is indicated by the fact that, in order to improve noise immunity, it is equipped with a hn monovibrator and a decoder, with the 'outputs the counter is connected to the inputs of the decoder, one output of the decoder is connected to the input of the second trigger 'directly, and the output bus of the code pulses through a mono / vibrator and the first logic element, And. the second output of the decoder is connected to the output bus of the synchronizing pulses and the third output of the decoder is connected to the input of the zero setting of the counter, the output of the monovibrator is connected to the input of the pulse shaper, the output of the second trigger is connected to the second element 65I, and the output of the zero-organ is connected with five 758243 '6 the third element And through the first trigger.