JP2588907B2 - Signal detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal detection device, and more particularly, to a device in which information is recorded at high density with a digital bit "1" corresponding to a maximum inclination position of a signal waveform. For detecting a signal reproduced from a magnetic recording medium.

[Conventional technology]

Conventionally, as a recording method on a magnetic recording medium, IMTDB, Vol. 26, No. 1, pp. 11-12 (1983) [IB
M TDB Vol 26, No. 1, pp. 11-12 (1983)], the bit “1” is converted into two pulse currents of the same sign, and the bit “0” is converted into two pulse currents of the different sign. FIG. 7 shows an example of a signal detecting apparatus for recording the data as described in Japanese Patent Application No. 61-19919. The operation of the conventional circuit of FIG. 7 will be described with reference to the timing chart of FIG. When a recording medium (not shown) recorded with the recording current shown in FIG. 8A is reproduced by the reproducing head 31 using the conventional technique,
The reproduced signal shown in FIG. 8B is obtained. After the signal (b) is amplified by the preamplifier 32, it is input to the differentiating circuit 33. The output waveform (c) is clamped to the positive polarity and the negative polarity with the clamp voltage Vc using the comparators 34 and 36, respectively, to obtain gate signals (d) and (e) for detecting the maximum tilt position. on the other hand,
The output signal (c) of the differentiating circuit 33 is further differentiated by the differentiating circuit 35 to become a signal (f). This second derivative signal (f)
And the gate signals (d) and (e), the comparators 37 and 38 are driven, and the pulse trains (g) and (h) rising at the zero-cross position of the signal (f), that is, the maximum inclination position of the waveform (b). Get. Further, the two pulse trains (g) and (h) are added by the OR circuit 39, and the flip-flop 40 reproduces the signal (i) inverted at the position corresponding to the bit "1", that is, the recorded data. is there.

[Problems to be solved by the invention]

The above-mentioned prior art discloses a signal-to-noise ratio (Sp) of a reproduced signal (b).
When −p / Np−p) is good, it is possible to accurately detect the maximum tilt position. However, when the signal-to-noise ratio is reduced to, for example, about 3 to 4 due to a narrow track or a high recording density, the signal-to-noise ratio is greatly reduced due to the enhancement of the high-frequency region by the two-stage differentiating circuit, and the detection capability is remarkable. There is a problem that this is expected to decrease and is not suitable as a high-density signal detection method.

SUMMARY OF THE INVENTION An object of the present invention is to provide a detection / detection device capable of maintaining good detection performance even when the quality of a signal is reduced due to a narrow track or a high recording density.

[Means for solving the problem]

The above object is to obtain a peak hold waveform or an envelope waveform without using a differentiating circuit which is a problem in the conventional configuration, and to manipulate a reproduced waveform without a large waveform manipulation.
This is achieved by directly detecting the maximum inclination position of the reproduced waveform.

FIG. 1 shows a basic configuration of the detection device according to the present invention, and FIG. 2 shows a waveform example of each component signal and a timing chart. The positive-phase input signal 12 (+ Vi
n) is a detection circuit block 30-2 having the same internal configuration.
, An input signal 13 (−Vin) having a reversed phase is input. There are a peak hold circuit 1 for obtaining a peak hold waveform from the waveform of the input signal 12 and an envelope detection circuit 3 for obtaining an envelope waveform. The envelope detection signal 16 is subtracted from the peak hold signal (+) 14 by a subtraction circuit 5. A floating gate signal 17 is obtained. The gate signal 17 and the input signal 12 are compared by the comparator 7, and the output 19 is pulsed by the monomulti 9 to form the set signal 21. On the other hand, a reset signal 22 is obtained from the detection circuit block 30-2 to which the input signal 13 of the opposite phase is input, through the same signal operation as described above. Further, the set signal 21 and the reset signal
From 22, a detection output 23, Vou, which is inverted at the signal maximum inclination position, by forming a rectangular output with the RS flip-flop 11
get t.

[Action]

The operation of the circuit shown in FIG. 1 will be described with reference to the signal waveform diagram shown in FIG. In the input signal 12 (+ Vin) indicated by the solid line, the center of the signal amplitude is shifted from the zero level by the data pattern. Therefore, a simple comparison between the zero level and the input signal 12 cannot detect an accurate magnetization reversal position. This is the same even if waveform processing such as slimming is performed.

Therefore, in the present invention, the peak hold signal indicated by the broken line
A floating gate signal 17 indicated by a dashed line is formed from the signal 14 and the envelope detection signal 16, and the center of the signal amplitude is detected by comparing the floating gate signal 17 with the input signal 12. As a result, it is possible to obtain the detection output 23 in which the center level of the signal amplitude based on the data pattern is corrected, and it is possible to detect the accurate maximum tilt position of the input signal Vin. On this occasion,
In the waveform processing, for example, it is not necessary to reinforce an extremely high frequency region such as differentiation, so that the signal quality does not deteriorate.

〔Example〕

A first embodiment of the present invention will be described with reference to FIG. An input signal + Vin is peak-held by a peak hold circuit 1 having a gentle discharge characteristic, and an input signal −Vin having an opposite phase to + Vin is beam-held by a peak hold circuit 2. 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 with a low-pass filter. A signal obtained by multiplying the envelope detection signal by a constant (K times, K is a numerical value in the range of 0 to 1) from the signal is subtracted by a subtraction circuit 5, and the resulting signal is subtracted by an input signal + Vin. By comparison, a pulse falling at the falling position of + Vin is obtained. 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 the subtraction circuit 6, and the resulting signal is compared with the input signal -Vin, whereby the falling position of -Vin, that is, + V
Obtain a rising pulse at the rising position of in. From the rises of these pulses, pulses having a short pulse width are formed by the monomultis 9 and 10 and input to the RS flip-flop 11 to obtain a detection output Vout.

In this embodiment, since the input voltage level of the comparator is located near zero level, the operation level of the comparator can be set low near zero level. Therefore, the design becomes easy, and the power consumption of the comparator can be reduced. Also, the subtraction circuits 5 and 6
Since the signals to be handled are an envelope detection signal and a peak hold signal and a signal of a relatively low frequency, it can be realized with a low-speed and simple circuit.

A second embodiment of the present invention will be described with reference to FIG. The input signal + Vin is peak-held by a peak hold circuit 1 having a gradual discharge characteristic, and the input signal -Vin having a phase opposite to + Vin is peak-held by a peak hold circuit 2. An 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 which integrates the output signal with a low-pass filter. Adder circuit 51 multiplies the signal multiplied (K times) and input signal + Vin
The signal of the addition result is compared with the output signal of the peak hold circuit 1 by the comparator 7 to obtain + Vi
Obtain a pulse that rises at the falling position of n. On the other hand, a signal obtained by multiplying the envelope detection signal by a constant value is added to the input signal -Vin, and a signal of this addition result and the peak hold circuit 2
The comparator 8 compares the output signal of
, Ie, a pulse rising at the + Vin rising position. Furthermore, from these pulses, a pulse with a short pulse width is created by monomulti 9 and 10, and each pulse is
By inputting to RS flip-flop 11, detection output
Get Vout.

In the present embodiment, for example, the adder circuits 51 and 61 connect the envelope signals to the (−) side input terminals of the comparators 7 and 8 via resistors, and the input signals ± Vin are AC-coupled via capacitors. Therefore, the circuit configuration can be simplified.

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

This embodiment is different from the embodiment shown in FIG.
In this configuration, two reset signal lines drawn from the output terminals are added and connected to the reset terminals of the 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 configuration of FIG. 5, since the output signal of the monomulti 10 is the reset signal of the peak hold circuit 101, the output signal is reset at the rising position of the input signal + Vin, and immediately thereafter, the peak hold operation is performed.

According to this embodiment, there is an advantage that the adders 51 and 52 can be easily realized as in the second embodiment shown in FIG.
Since the peak hold circuits 101 and 102 follow almost every bit, there is an advantage that an extremely accurate envelope signal can be synthesized.

Note that the peak hold circuits 101 and 102 of this embodiment are
Obviously, the same effect is obtained even when applied to the first embodiment shown in the figure.

Further, it is clear that the same operation can be obtained even if the SR flip-flops of all the above-described embodiments are replaced with an OR circuit and a T flip-flop.

In the above-described embodiment, the bit “1” corresponds to the maximum slope position of the waveform, such as the reproduced waveform at the time of double pulse recording. However, the magnetization reversal position corresponds to the peak position of the reproduced waveform. In the detection of the reproduction waveform of the recording method as well, as illustrated in FIG. 6, an equivalent circuit 41 such as an integration circuit is provided in the preceding stage of the detection device according to the present invention, and the peak position of the reproduction waveform is converted into the maximum inclination position. It can be easily applied.

〔The invention's effect〕

According to the present invention, it is possible to detect the maximum inclination position of a signal waveform without applying a circuit for enhancing a high frequency region such as a differentiating circuit. Therefore, even if the signal quality is deteriorated, good detection performance can be maintained.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a timing chart of signals of respective parts for explaining the operation thereof, FIGS. 3, 4, and 5 are configuration diagrams of an embodiment of the present invention, respectively. FIG. 7 is a block diagram of an embodiment when the present invention is applied to a reproduction system using another recording method, FIG. 7 is a block diagram of a conventional example, and FIG. 8 is a timing chart of signals of respective parts for explaining the operation. 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 ... reproduction head 41 ... waveform equalization circuit 51, 61 ... Adder circuit

Claims (4)

(57) [Claims] An apparatus for detecting a signal reproduced from a medium in which information is recorded by associating a maximum slope position of a signal waveform with a digital bit "1", wherein a peak hold waveform and an envelope waveform of an input signal waveform are detected. Means to seek,
Means for obtaining a floating gate signal by subtracting a constant multiple of the obtained envelope waveform from the peak hold waveform,
Means for comparing the floating gate signal with the input signal is provided for each of two input signals whose phases are reproduced from the recording medium, and the maximum slope of the input signal waveform is determined by the comparison result signals from the two comparing means. A signal detection device for obtaining a detection output for gating at a position. 2. The signal according to claim 1, wherein said means for obtaining an envelope waveform of said input signal waveform is obtained by passing said peak hold waveform through a low-pass filter. Detection device. 3. A signal detection device for a reproduced signal from a medium in which information is recorded by associating a maximum slope position of a signal waveform with a digital bit "1", wherein a peak hold waveform and an envelope waveform of an input signal waveform are detected. Means to seek,
Means for adding a constant multiple of the determined envelope waveform to the input signal waveform and comparing the floating input signal waveform with a peak hold waveform for each of two input signals whose phases reproduced from the recording medium are inverted from each other; A signal detection device for obtaining a detection output for gating at a maximum inclination position of an input signal waveform based on a comparison result signal from the two comparison means. 4. A signal detecting apparatus according to claim 3, wherein said means for obtaining the envelope waveform of said input signal waveform is obtained by passing said peak hold waveform through a low pass filter. apparatus.