KR0129966B1 - Data reproducing circuit - Google Patents

Abstract

A method and a circuit for replaying a data signal are disclosed. The method for replaying a data signal in a digital magnetic replaying system comprises: a step of detecting a zero cross point of the replayed signal; a step of detecting a rising edge and a falling edge of the zero cross point detecting signal to detect an inversing time of an original digital data prior to be recorded at the magnetic recording medium; and a step of recovering the replayed signal to the original digital data.

Description

Data playback method and circuit

1 is a block diagram showing a general reproduction system in a digital magnetic recording and reproducing apparatus.

FIG. 2 is a block diagram showing a conventional data reproduction circuit in FIG.

3 is a block diagram showing a reproduction system to which the data reproduction circuit according to the present invention is applied in the digital magnetic recording reproduction apparatus.

4 is a detailed block diagram of a data reproducing circuit according to the present invention in FIG.

5A to 5J are operational waveform diagrams of the respective parts in FIG.

* Explanation of symbols for main parts of the drawings

10: regeneration amplifier 20: regeneration equalizer

30: zero cross detector 31: differentiator

33: non-inverting amplitude regulator 35: inverting amplitude regulator

37, 41, 45: comparator 40: data edge detector

43, 47: endgate 50: data player

51 Inverter 53 J-K flip-flop

100: data reproduction circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data reproducing method and circuit in a digital magnetic recording and reproducing apparatus, and more particularly to a data reproducing method for faithfully reproducing digital data from a recording medium by accurately detecting each inversion time of the digital data before being recorded on the recording medium. It is about a circuit.

FIG. 1 is a block diagram showing a general reproducing system in a digital magnetic recording and reproducing apparatus, and FIG. 2 is a block diagram showing a conventional data reproducing circuit 3 in FIG. 1, where the integrator 4 and the comparator 5 are shown. It consists of.

1 and 2, a reproduction head (not shown) is amplified to a predetermined size by digital reproduction data reproduced from a recording medium and applied to the reproduction equalizing unit 2. The reproduction equalizing unit 2 performs waveform correction so that the output signal of the reproduction amplification unit 1, which is closer to the analog signal, i.e., the reproduction digital data signal, can be easily converted into the original digital data. Output

The integrator 4 among the components of the data reproducing circuit 3 integrates the output signal of the reproducing equalizer 2 and applies the integrated value to the reference signal Vref of the comparator 5. The comparator 5 compares the output signal of the reproduction equalizer 2 with the output signal of the integrator 4, that is, the reference signal, and detects and outputs only a signal of a predetermined magnitude or more.

However, in the digital magnetic recording and reproducing apparatus, when the digital data recorded on the magnetic recording medium is reproduced by the conventional data reproducing circuit, the magnetic recording medium itself has a characteristic closer to the analog signal, and the derivative of the magnetic recording medium is different. Due to the characteristics, the analog signal characteristic of the amplitude is raised or lowered up or down in each inversion section of the digital data during recording.

The degree of accurately detecting each inversion point of the original digital data in the reproduction signal having the analog characteristics has a decisive influence on the bit error rate of the entire digital magnetic recording / reproducing apparatus.

Therefore, in the conventional data reproducing circuit using the integral method, there is a slight difference in the amount of integration depending on the amplitude of the signal, so that it is impossible to accurately detect the inversion time, and the bit error rate of the entire digital magnetic recording / reproducing apparatus becomes high. There was this.

Accordingly, an object of the present invention is a data reproducing method for faithfully reproducing digital data from a recording medium by accurately detecting each inversion point of digital data before recording on the recording medium in the digital magnetic recording and reproducing apparatus to solve the above problems. To provide.

Another object of the present invention is to provide a circuit most suitable for realizing the above data reproducing method.

In order to achieve the above object, a data reproducing method according to the present invention comprises: a zero cross detection step of detecting a zero cross point of a signal reproduced from a magnetic recording medium; A data edge detection step of detecting an inversion point of digital data before being recorded on the magnetic recording medium by detecting rising and falling edges of the signal detected in the zero cross detection step; And a data reproducing process of recovering the digital data before the data is recorded on the magnetic recording medium from the signal detected in the data edge detection process.

According to another aspect of the present invention, there is provided a data reproducing circuit, comprising: a zero cross detector for detecting a zero cross point of a signal reproduced from a magnetic recording medium; A data edge detector for detecting an inversion point of digital data before being written to the magnetic recording medium by detecting an edge of a signal output from the zero cross detector; And a data reproducing unit for recovering the digital data before being recorded on the magnetic recording medium from the signal output from the data edge detecting unit.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram showing a reproduction system to which the data reproduction circuit according to the present invention is applied in the digital magnetic recording reproduction apparatus.

The configuration of the block diagram shown in FIG. 3 includes a reproduction amplifier section 10, a reproduction equalizing section 20, and a data reproduction circuit 100. As shown in FIG.

On the other hand, the data reproducing circuit 100 detects edges of the signal output from the zero cross detector 30 and zero cross detector 30 for detecting the zero cross point of the signal reproduced from the magnetic recording medium. A data edge detector 40 for detecting the inversion time of the digital data before recording, and a data reproducing unit 50 for recovering the digital data before being recorded on the magnetic recording medium from the signal output from the data edge detector 40; It consists of.

4 is a detailed block diagram of the data reproducing circuit 100 according to the present invention in FIG.

In the block diagram shown in FIG. 4, the zero cross detection unit 30 has a first predetermined amplitude in phase with respect to the differentiator 31 which differentiates the signal reproduced from the magnetic recording medium and the signal output from the differentiator 31. The non-inverted amplitude adjuster 33 adjusts to, the inverted amplitude adjuster 35 adjusts to the second predetermined amplitude in reverse phase with respect to the signal output from the differentiator 31, and the output from the non-inverted amplitude adjuster 33. And a first comparator 37 for generating a square wave including a zero cross point of the differentiated reproduction signal by comparing the signal to be output from the inverted amplitude adjuster 35.

On the other hand, the data edge detector 40 includes a second comparator 41 for detecting a square wave of a section above the first reference potential in the signal reproduced from the magnetic recording medium, and a section below the second reference potential in the signal reproduced from the magnetic recording medium. A third comparator 45 for detecting a square wave, a first end gate 43 for performing a logical product on the output signal of the zero cross detector 30 and the output signal of the second comparator 41, and a zero cross detector. And a second AND gate 47 performing an AND operation on the output signal of 30 and the output signal of the third comparator 45.

On the other hand, the data reproducing section 50 is an inverter 51 for inverting the output of the second and gate 47, and the output of the inverter 51 is a clear terminal CLR, and the output of the first and gate 43 is output. Are respectively applied to the clock terminal CK, and are composed of a JK flip-flop 53 in which J, K, and preset terminals PRESET are left in a 'high' logic state.

5A to 5J are the operating waveform diagrams of the respective parts in FIG. 4, FIG. 5A is digital data before being recorded on the recording medium, FIG. 5B is an output signal of the reproduction equalizer 20, and FIG. 5C is a non-inverting amplitude adjuster (FIG. The output signal of the 33 and the inverted amplitude regulator 35, the 5d is the output signal of the first comparator 37, the 5e is the output signal of the second comparator 41, the 5f is the third comparator 45 5g is an output signal of the first and gate 43, 5h is an output signal of the second and gate 47, 5i is an output signal of the inverter 51, 5j is a JK flip-flop The output signal of the Q terminal of (53) is respectively shown.

The operation of the present invention will now be described with reference to FIGS. 3 to 5.

For example, the digital data before recording to the recording medium as shown in FIG. 5A is reproduced from the recording medium and passed through the reproduction amplifier unit 10 and the reproduction equalizing unit 20. As shown in FIG. The data (Figure 5a) is pushed up or down in the inversion section. The digital data (FIG. 5b) output from the reproduction equalizing unit 20 is differentiated from the differentiator 31 of the zero cross detection unit 30 and applied to the non-inverting amplitude regulator 33 and the inverted amplitude regulator 35, respectively.

The non-inverting amplitude regulator 33 amplitude-controls the output signal of the differentiator 31 in phase, and outputs a signal crossing the zero potential at each of the upper and lower peaks of the waveform of FIG. 5b as in the a waveform of FIG. 5c. On the other hand, the b waveform which phase-inverted the a waveform of FIG. 5C is a waveform of the signal output from the inversion amplitude regulator 35. In FIG.

The first comparator 37 uses the output signal of the non-inverting amplitude regulator 33 (a of FIG. 5c) as an input signal, and uses the output signal of the inverted amplitude regulator 35 (b of FIG. 5c) as a reference signal. As shown in FIG. 5D, the logic state 'high' is output for the input signal section larger than the reference signal.

On the other hand, a region with a long inversion section of digital data (Fig. 5a) recorded on the recording medium passes through the ground level as shown in Fig. 5b during reproduction. It is an 'unknown state' that can be 'high' or 'low' logic depending on the surrounding conditions such as noise is introduced. That is, the final output of the zero cross detection unit 30 (FIG. 5D) is composed of a pulse including the original digital data inversion section (↓, ↑ in FIG. 5D) and an 'unknown state'.

In the data edge detector 40, a second comparator 41 and a second region are formed in the reproduction signal (FIG. 5B), which is equal to or greater than the positive reference potential (+ V _ref ) and which is equal to or less than the negative reference potential (-V _ref ). The third comparator 45 derives a square wave as shown in FIG. 5E and FIG. 5F and applies them to the first and second gates 43 and 47, respectively. In the first and gate 43, the output of the fifth g degree is output by ANDing the output of the second comparator 41 (FIG. 5e) and the output of the zero cross detector 30 (FIG. 5d), and outputting the signal of FIG. At 47, the output of the third comparator 45 (figure 5f) and the output of the zero cross detection section 30 (figure 5d) are ANDed so as to output the signal of FIG. 5h. That is, the final output (figure 5g and FIG. 5h) of the data edge detector 40 determines the rising edge time point (↓ in FIG. 5g) and the falling edge time point (↑ in FIG. 5g) of the original digital data (figure 5a). It consists only of the pulses it contains.

In the data reproducing section 50, the signal (Fig. 5i) inverted by the inverter 51 (Fig. 5h) of the second and gate 47 is transmitted to the clear (CLR) terminal of the JK flip-flop 53. After applying the output of the first and gate 43 (figure 5g) to the clock (CK) terminal, the J, K, and the preset (PR) terminal is tied to the 'high' logic state JK flip-flop ( 53), the original digital data (figure 5j) is restored while being in a 'low' logic state at the falling edge of the first and gate 43 outputs (figure 5g).

As described above, in the data reproducing method and circuit according to the present invention, the digital magnetic recording and reproducing apparatus eliminates inconsistencies in the amount of group delay caused by error in the existing data reproducing circuit employing the integral method, and eliminates the original digital data. By accurately detecting the reversal of, there is an advantage in that malfunctions of devices installed in the rear stage can be prevented and the bit error rate of the entire reproduction system can be improved.

Claims (2)

A data reproducing circuit which detects a zero cross signal representing a zero cross point of a signal reproduced from a magnetic recording medium and reproduces digital data, wherein a section having a predetermined potential above and below a signal reproduced from the magnetic recording medium is output as a square wave. A data edge detector configured to logically multiply the zero cross signal and the output square wave to detect rising and falling edge signals including rising and falling peaks of the reproduced signal; And a data reproducing unit for reproducing original digital data from the edge signal detected by the data edge detecting unit, wherein the data reproducing unit has a high logic state between a rising peak and a falling peak of the reproduced signal, And a unknown state in the reproduction data so as to be in a low logic state between the rising peaks. The display apparatus of claim 1, wherein the data reproducing unit comprises: an inverter for inverting the falling edge signal detected by the data edge detecting unit; And a JK flip-flop that applies an output of the inverter to a clear terminal, applies a rising edge signal detected by the peak detector to a clock terminal, and sets J, K, and preset terminals to a 'high' logic state. A data reproducing circuit.