JPH0192904A - Signal detection system - Google Patents

Abstract

PURPOSE:To obtain excellent detection performance even with narrow track processing or high density recording by obtaining a peak hold waveform and an envelope waveform so as to detect the maximum tilt position of a reproduced waveform directly without much processing of the reproduced waveform. CONSTITUTION:A noninverting input signal 12 is given to a detection circuit block 301 and an input signal 13 whose phase is inverted is given to a detection circuit block 30-2. A peak hold circuit 1 obtaining a peak hold waveform from the waveform of the input signal 12 and an envelope detection circuit 3 obtaining the envelope waveform are provided and a floating gate signal 17 is obtained from the waveforms. The gate signal 17 and the input signal 12 are compared and the output 19 is processed into a pulse by a monostable multivibrator 9 to form a set signal 21. On the other hand, a reset signal 22 is obtained from a detection circuit block 30-2 receiving the inverted input signal 13 and a detection output 23 (Vout) inverted at the signal maximum tilt position is obtained from the set signal 21 and the reset signal 22. Thus, even with narrow track processing or high density recording took place, excellent detection performance is maintained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a signal detection method, and in particular, a method in which information is recorded with high density by making digital bits It 1 jP correspond to the maximum slope position of a signal waveform. The present invention relates to a method for detecting a reproduced signal from a magnetic recording medium.

[Conventional technology]

Conventionally, as a recording method for magnetic recording media, IBM TDB, Vol. 26, No. 1, pp. 11-12 (19
83) (IBM TDB VoQ 26.N
(11゜pH~12 (1983)), when bit “1” is converted into two pulse currents with the same sign and bit “0” is converted into two pulse currents with different signs. As a signal detection method, there is one having the configuration shown in FIG. 7, as described in Japanese Patent Application No. 17919/1983. The operation of the conventional circuit shown in FIG. 7 will be explained using the timing chart shown in FIG. When a recording medium (not shown) recorded with the recording current shown in FIG. 8(a) is reproduced by the reproducing head 31 using the conventional technique, the reproduced signal shown in FIG. 8(b) is obtained. This signal (b
) is amplified by the preamplifier 32 and then input to the differentiating circuit 33. The output waveform (C) is clamped to positive polarity and negative polarity by the clamp voltage Vc using comparators 34 and 36, respectively, and the gate signal (d) for detecting the maximum inclination position, (
obtain e). On the other hand, the output signal (c) of the differentiating circuit 33 is
Further, it is differentiated by a differentiating circuit 35 to become a signal (f).

This second-order differential signal (f) and the gate signal (d).

(e) drives the comparators 37 and 38,
Pulse trains (g) and (h) are obtained that rise at the zero-crossing position of the signal (f), that is, at the maximum slope position of the waveform (b). Further, the two pulse trains (g) and (h) are added by an OR circuit 39, and a flip-flop 40 reproduces a signal (i) that is inverted at a position corresponding to bit "'1", that is, recorded data. It is.

[Problem that the invention seeks to solve]

The above conventional technology has a signal-to-noise ratio (Sp
-p/Np-p), it is possible to accurately detect the maximum tilt position. However, when the signal-to-noise ratio drops to, for example, 3 to 4 due to narrower tracks and higher recording density, the signal-to-noise ratio decreases significantly due to the enhancement of the high frequency region by the two-stage differentiating circuit, and the detection ability significantly deteriorates. The problem is that this is not suitable as a high-density signal detection method.

An object of the present invention is to provide a signal detection method that can maintain good detection performance even if signal quality is degraded due to narrower tracks or higher recording density.

[Means for solving problems]

The purpose of the above is to directly detect the maximum slope position of the reproduced waveform by determining the peak hold waveform and envelope waveform without using a differentiating circuit, which is a problem in conventional configurations, and without greatly manipulating the reproduced waveform. This is achieved by doing this.

The basic configuration of the detection method according to the present invention is shown in FIG. 1, and examples of waveforms and timing charts of the signals of each part are shown in FIG.
A positive phase input signal 12 (+
Vin) is the detection circuit block 3 having the same internal configuration.
0-2 has an input signal 13 (-V
in) is input. There is a peak hold circuit 1 that obtains a peak hold waveform from the waveform of an input signal 12, and an envelope detection circuit 3 that obtains an envelope waveform. A floating gate signal 17 is obtained. The gate signal 17 and the input signal 12 are compared by a comparator 7, and the output 19 is converted into a pulse by a monomulti 9 to form a set signal 21. On the other hand, the reset signal 22 is obtained from the detection circuit block 30-2 to which the input signal 13 of opposite phase is inputted, through the same signal manipulation as described above.

Furthermore, from the set signal 21 and reset signal 22, RS
By forming a rectangular output with the flip-flop 11, the detection output 23 is inverted at the signal maximum slope position. Vou
get t.

[Effect]

The operation of the circuit shown in FIG. 1 will be explained using the signal waveform diagram illustrated in FIG. The solid line input signal 12 (+Vin) is
The data pattern shifts the center of the signal amplitude from the zero level. For this reason.

A simple comparison between the zero level and the input signal 12 cannot detect an accurate magnetization reversal position, and this is true even if waveform processing such as slimming is performed.

Therefore, in the present invention, the floating gate signal 17 is constructed from the peak hold signal 14 and the envelope detection signal 1G, as shown by the dashed line, and this and the input signal 12
The center of the signal amplitude is detected by comparing with . As a result, it is possible to obtain a detection output 23 in which the center level of the signal amplitude according to the data pattern is corrected.
The accurate maximum slope position of the input signal Vin can be detected. At this time, the waveform processing does not require extreme enhancement of high frequency regions such as differentiation, so no deterioration in signal quality occurs.

〔Example〕

A first embodiment of the present invention will be explained with reference to FIG.

An input signal Vin is peak-held by a peak-hold circuit 1 having a gradual discharge characteristic, and an input signal -Vin having an opposite phase to +Vin is peak-held by a peak-hold circuit 2. The envelope detection signal is detected by passing the sum of the output signals of these two peak hold circuits 1 and 2 through an envelope detection circuit 3 that integrates it with a low-pass filter. From the signal, a signal obtained by multiplying the envelope detection signal by a constant (K times, K is selected from a range of 0 to 1) using a coefficient unit 4 is subtracted from the signal by a subtraction circuit 5, and the signal resulting from this subtraction is input to the input signal '+Vin. By comparing with +Vin
Obtain a pulse that rises at the falling position of . On the other hand, a constant multiple of the envelope detection signal is subtracted from the output signal of the peak hold circuit 2 by a subtraction circuit 6, and the signal resulting from this subtraction is compared with the input signal -Vin to determine the falling position of -Vin, that is, +Vin. Obtain a pulse that rises at the rising position of . From the rising edge of these pulses, pulses with short pulse widths are generated by monomultiply circuits 9 and 10, and the detection output Vout is obtained by inputting each pulse to the RS flip-flop 11.

In this embodiment, since the input voltage level of the comparator is located near the zero level, the operating level of the comparator can be set low, near the zero level. Therefore, the design becomes easy and the power consumption of the comparator can be reduced.

Furthermore, since the subtraction circuits 5 and 6 handle relatively low-frequency signals such as an envelope detection signal and a peak hold signal, they can be realized with a low-speed and simple circuit.

A second embodiment of the present invention will be explained with reference to FIG.

The input signal Vin is held at its peak by a peak hold circuit 1 having gradual discharge characteristics.

The peak hold circuit 2 holds the input signal -Vin, which has an opposite phase to +Vin. The envelope detection signal is detected by passing the sum of the output signals of the two peak hold circuits 1 and 2 through an envelope detection circuit 3 that integrates it with a low-pass filter. By adding the multiplied (K times) signal and the input signal Vin in the adder circuit 51, and comparing the signal resulting from this addition with the output signal of the peak hold circuit 1 in the comparator 7, +V'in Obtain a pulse that rises at the falling position of . On the other hand, by adding a signal obtained by multiplying the envelope detection signal by a constant to the input signal -Vin, and comparing the signal resulting from this addition with the output signal of the peak hold circuit 2 in the comparator 8, the falling position of -Vin is determined. , that is, a pulse that rises at the rising position of +Vin is obtained. Furthermore, from these pulses, pulses with short pulse widths are created using a monomulti 9.10, and by inputting each pulse to the RS flip-flop 11, the detection output V
Get out.

In this embodiment, for example, the adder circuit 51.61 includes the comparator 7.
, 8 (-) input terminals via resistors, and input signals ±Vin are easily realized by AC coupling via capacitors, making it possible to simplify one circuit configuration. .

A third embodiment of the present invention will be explained with reference to FIG.

This embodiment is based on the monomulti 10. in the embodiment shown in FIG.
In this configuration, two reset signal lines drawn out from the output terminal of 9 are added and connected to the reset terminals of peak hold circuits 101 and 102, respectively.

The peak hold circuits 101 and 102 operate to keep the peak held voltage constant unless a reset signal is input.

In the implantation shown in FIG. 5, since the output signal of the monomulti 1O is the reset signal of the peak hold circuit 101, it is reset at the rising position of the input signal Vin, and then immediately performs the peak hold operation.

According to this embodiment, in addition to the advantage that the adder circuits 51 and 52 can be easily implemented as in the second embodiment shown in FIG. 4, the peak hold circuits 101 and 102 follow almost every bit. Therefore, there is an advantage that envelope signals with extremely high precision can be synthesized.

It is clear that the same effect will be produced even if the peak hold circuits 101 and 102 of this embodiment are applied to the first embodiment shown in FIG.

Furthermore, it is clear that the same effect can be achieved even if the SR flip-flops in all the embodiments described above are replaced with OR circuits and T flip-flops.

The embodiment described above deals with the case where the bit It 117 corresponds to the maximum slope position of the waveform, such as the reproduced waveform during double pulse recording. The method can also be easily applied to the detection of reproduced waveforms by providing an equalization circuit 41 such as an integrating circuit at the front stage of the detection method according to the present invention, as illustrated in FIG.

〔Effect of the invention〕

According to the present invention, it is possible to detect the maximum slope position of a signal waveform without applying a circuit that enhances the high frequency region, such as a differential circuit, and as a result, it is possible to narrow the track and increase the recording density. Good detection performance can be maintained even if signal quality is degraded.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a timing chart of signals of each part for explaining its operation, FIGS. 3, 4, and 5 are configuration diagrams of an embodiment of the present invention, and FIG. 6 7 is a configuration diagram of an embodiment in which the present invention is applied to a reproduction system using another recording system, FIG. 7 is a configuration diagram of a conventional example, and FIG. 8 is a timing chart of signals of each part for explaining its operation. Explanation of symbols 1, 2, 101.102... Peak hold circuit 3... Envelope detection circuit 5.6... Subtraction circuit 7.8... Comparator 9.10... Monomulti 11...・SR flip-flop 31...Playback head 41...Waveform equalization circuit 51, 61...Addition circuit Patent attorney Junnosuke Nakamura 23:To". Figure 5 6th factor 41-4C circuit 200 - Ichigogo appearance 1 each 3 times
1----To the second king 5,7 to 33.35-11 mold now circuit 34.36.37.38 ---ko〉Batota 39-Crystal 4〕Circuit 40---F8, def 00 ．． , PuVc---Franide/N'anti+0 1 1 00 1 (j)+o++oo+

Claims (1)

[Claims] 1. The maximum slope position of the signal waveform is set to digital bit “1”.
In a signal detection method for a reproduced signal from a medium on which information is recorded corresponding to ", a means for determining a peak hold waveform and an envelope waveform of an input signal waveform, and a means for subtracting a constant multiple of the determined envelope waveform from the peak hold waveform. and a means for comparing the floating gate signal with an input signal are provided for each of the two input signals whose phases are inverted from each other reproduced from the recording medium, and A signal detection method characterized in that a detection output is obtained by gating at a maximum slope position of an input signal waveform based on a comparison result signal. 2. The means for determining an envelope waveform of the input signal waveform includes a low-pass pass through the peak hold waveform. 3. The signal detection method according to claim 1, wherein the signal detection method is obtained by passing the signal waveform through a digital filter.
In a signal detection method for a reproduced signal from a medium on which information is recorded corresponding to ", a means for determining a peak hold waveform and an envelope waveform of an input signal waveform, and an integral multiple of the determined envelope waveform are added to the input signal waveform. A means for obtaining a floating input signal waveform and a means for comparing the floating input signal waveform with a peak hold waveform are provided for each of two input signals whose phases are reversed to each other reproduced from a recording medium. A signal detection method characterized in that a detection output is obtained by gating at the maximum slope position of the input signal waveform based on comparison result signals from two comparison means. 4. The means for determining the envelope waveform of the input signal waveform includes the peak hold 4. The signal detection method according to claim 3, wherein the signal detection method is obtained by passing the waveform through a low-pass filter.