SU1223288A1 - Device for reproducing digital information from magnetic record medium - Google Patents

Abstract

This invention relates to devices for reproducing digital information from a magnetic recording medium. The purpose of the invention is to reduce the error in reproducing digital information from a magnetic recording medium. The device contains a magnetic head 1, a playback amplifier 2, an amplitude-frequency correction element 3, threshold elements 4 and 16, elements OR 5.17 and 18, amplifier limiter 6, demodulator 7, start signaling device 8, triggers 9 and 10, counters 11 , 12 and 13, block 14 of the installation of the shift of the clock signal, the generator 15 pulses. A trigger 20, an input clock 21 of the clock signal, a decoder 22, elements 23 and 24, inverters 25 and 26 are introduced into the device. The introduction of new elements and the formation of new connections between the elements of the device allow the invention to be achieved. In the absence of deep drops out of the reproduced phase-modulated (FM) signal, the threshold elements 4 and 16 form rectangular signals which, through the OR 5 element, arrive at the AND 24 element. The signal formed by the AND 24 element maintains the zero state of the counter 12 and sets the output trigger, a signal that provides the opening element And 23 for the clock signal of the first trigger 9. 1 Il. W CZ Yu tc with N9 00 00

Description

The invention relates to the field. recording devices, namely, devices for reproducing digital information from a magnetic recording medium.

The purpose of the invention is to reduce the reproduction error of digital information from a magnetic recording medium.

The drawing shows a proposed device for reproducing digital information from a magnetic recording medium.

The device contains a magnetic go-ioBKy 1 connected through an amplifier

2plays with element input

3 amplitude-frequency correction, the output of which is connected through the first threshold element 4 to the first input of the first element OR 5 and connected to the input of the amplifier-limiter 6, blower 7, driver 8 start signal, the first and second triggers 9 and 10, the first, the second and third counters 11–13, the clock offset setting unit 14, the pulse generator 15, the second threshold element 16, and the second and third elements OR 17 and 18. The output of the amplifier-limiter 6 is connected to the first. the input of the demodulator 7 connected to the output bus 19 of the information, and with the first input of the driver 8 start signal. The output of the start signal generator 8 is connected to the input of the first counter 11 and to the first input of the first trigger 9. The first trigger 9 is connected inversely to the second input of the start signal generator 8 and connected to the output of the first offset switch block 14 with the second input clock signal and the output of the generator 15 pulses.

The output of the second counter 12 is connected to the first input of the second trigger 10.

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The device also contains a third trigger 20 connected by a direct output to the first input of the second HS element 17 connected to the output bus 2I of the clock signal and to the VTO1NL4 input of demodulator 7, the decoder 22, the first and second elements And 23 and 24, and the first and second inverters 25 and 26. The decoder 22 is connected by inputs to the outputs of the three

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the second counter 13 and connected to the output of the first inputs of the third trigger and the third element OR 18. The output of the third element OR 18 is connected to the first input of the third counter 13 connected by the second input to the output of the pulse generator 15. The first element And 23 is connected by the first input to the forward output of the first trigger 9, connected by a second input to the inverse output of the second trigger and connected by an output to the second inputs of the second and third elements OR 17 and 18. The second element And 24 is connected by an output to the first input of the second counter 12 and connected by the first input to the output of the first element OR 5 connected by the second input to the output of the second threshold element 16. 0 The first inverter 25 is connected between the output of the element 3 amplitude-frequency correction and the input of the second threshold element 16. Torah inverter 26 is connected between the output of the start signal 8 and the second input of the second counter 12. The output signal puskgg driver 8 is connected to the second input of the second AND gate 24. The output of the first AND gate 23 is connected to the second input of the third flip-flop 20.

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Reproduction of digital information from a magnetic recording medium by means of the proposed device. occurs as follows.

The phase-modulated signal, reproduced by the magnetic head 1 with a magnetic recording detector, is fed through the reproduction amplifier 2 to the amplitude-frequency correction element 3. The amplifier-limiter "rubs the non-signal of the Element 3 amplitude-frequency correction rectangular phase-modulated signal to the demodulator 7 and to the start signal generator 8. The square-phase modulated signal pulse switches the start signal generator 8, which removes blocking, from the first trigger 9 and from the first counter 11. A quarter of a clock after that, at the output of the first counter 11, a first-second pulse appears that switches the first trigger, 9. Half a time after the first pulse of the first counter 11 appears, a second pulse appears at its output, which again switches the first trigger 9. At the same time, the positive level from the inverse output of the first counter 9 resets the start signal generator 8. The output of the forkshravtel 8 start signal appears high level, which fixes the first trigger 9 in the zero state and writes to the first counter 11 a binary code specified by the clock shift setting unit 14. From the next phase modulated signal of the limiting amplifier 6, the sig- nal pulse again switches the start signal generator 8 and repeats the same operation cycle of the first counter 11. As a result, a sync signal is output from the output of the first trigger 9 relative to the reproduced phase-modulated signal by a quarter tact I

The signal of amplitude-frequency correction element 3 is supplied to the first threshold element 4 directly, and to the second threshold element 1b through the first inverter 25. In the absence of deep depositions of the reproduced phase-modulated signal, the first and second threshold elements 4 and 16 form rectangular signals that, through the first the element OR 5. arrives at the second element AND 24. The signal formed by the second element AND 24 maintains the second counter 12 in the zero state and sets the inverse output of the second trigger polo a strong signal that provides the opening of the first. element 23 for the sync signal of the first trigger 9. With a deep loss of the reproduced phase-modulated signal, the first and second threshold epema & You 4 and 16 stop generating square signals, which causes the second counter 12 and the second trigger 10 to be released from blocking. The second counter 12 starts counting the level drops at the output of the driver B, the start signal acting on it through the second inverter 26. After two counts are calculated the second counter level 12. switches the second trigger 10 into one state, when the Topbift locks the first element AND 23 for the clock signal of the first trigger 9,

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In the absence of a sync signal at the output of the first element And 23, the double transformer 22 forms a continuous sequence of pulses in accordance with the signals of the third counter 13, excited by the generator of 15 pulses. This continuous sequence of pulses goes directly to the third trigger 20, and

10 through the third element of the ISH 18 - to the third counter 13. The third trigger 20 generates a sync signal coming through the second OR element 17 to the output bus 21 of the sync signal and

15, a demodulator -7, from the output of which the demodulation result is fed to the output bus 19 of information.

Claims (1)

Invention Formula 20 A device for reproducing digital information from a magnetic recording medium, comprising a magnetic head connected through a reproduction amplifier to an input of an amplitude-frequency correction element, the output of which is connected through the first threshold element to the first input of the first element OR and connected to the input of the amplifier-limiter, the output of which is connected to the first input of the demodulator connected. output to the output bus information, and with the first input of the start signal generator, connected by the output with the input of the first counter and the first input of the first trigger, which is connected by an inverse output to the second. mu input trigger signal and the second input is connected to the output of the first counter connected to the outputs of the clock shift setting unit and to the output of the pulse generator; the second counter connected to the output to the first input of the second trigger, the second threshold element, the second n the third elements OR, the third counter and the output clock of the clock signal, characterized in that, with In order to reduce the error in reproducing digital information, a third trigger is inserted into it, connected via the output to the first input of the second OR element connected output with a sync output bus and a second demodulator input, an encoder connected to the inputs of the third counter and a 512232886 connection valuable output to the first inputs of the first first input to the output of the first dark trigger and the third element OR connected by the second OR, connected to the first input to the output of the second threshold input of the third counter, the second element, the first inverter, the input of which is connected to output 5 between the output of the amplitude-pulse generator element, the first element of the no-frequency correction and the second AND input, connected by the first input to the left threshold element, the second first direct output of the first trigger, and connected between the output is a second input with an inverse starter of the start signal and a second output of the second trigger and is connected with the second input of the second counter, and the output output to the second inputs of the second shaper of the start signal is connected to the third element OR, the second element to the second the input of the second element is ment And connected by the output to the first I, and the output of the first element I to the input of the second counter and connected to the second input of the third trigger