JPH06103696A - Data signal reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To adjust the coefficients of the tap coefficient update circuits 123 to 127 according to the equalization error signal (104 output) of the difference between the expected value (103 output) and the equalized output (128 output). Thus, in a reproducing apparatus having an adaptive equalizer 102 (having delay circuits 114 to 117, multiplying circuits 118 to 122, and an adder 128) that automatically adaptively equalizes an input signal (reproduction signal) waveform, dropout, etc. Input signal amplitude is a predetermined value A
When the value of the input signal amplitude is returned to the original value, the adaptive equalization operation (tap update) is resumed immediately when the input signal amplitude returns to the original value. [Structure] Absolute value Vab of equalized output signal (128 outputs)
Envelope value update circuit 112 for updating s for each peak of the input to produce an equalized output envelope value Venv;
A comparator 134 that generates a detection signal when nv drops below a predetermined value A and gates 105 to 109 that stop tap update when a detection signal is generated are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data reproducing device, and more particularly to an adaptive device capable of preventing a malfunction of an adaptive waveform operation without being affected by a large change in an input signal level during data reproduction of a magnetic recording device. The present invention relates to a data signal reproducing device equipped with a rectifier.

[0002]

2. Description of the Related Art Generally, in a read circuit of a magnetic recording device, when data discrimination is performed after converting an analog reproduction signal from a magnetic head into a digital signal, a deterioration factor of an electromagnetic conversion system, for example, deterioration of high frequency components. Are affected by amplitude distortion, phase distortion, and external noise. Therefore, in order to faithfully reproduce the signal corresponding to the recording data, in order to correct the above-mentioned waveform distortion and remove high-frequency noise, a reading circuit composed of a waveform equalizer, a low-pass filter, etc. It is used.

Since the above-described technique cannot cope with the change in the recording / reproducing characteristics due to the variations in the recording medium, the magnetic head and the circuit system and the change in the characteristics of the recording medium of the magnetic head with time, the reliability of the read data is improved. There was a problem. As a means for compensating for this, an equalizer that automatically adjusts the characteristics of the equalizer according to a change in an input signal is generally called an automatic equalizer, and an adaptive filter is usually used.

FIG. 5 shows the structure of an equalizer / determiner using a transversal filter which has been conventionally used. In the figure, reference numeral 100 is a transversal filter equalizer, and this equalizer 100 is a delay element 10 connected in series.
0a (each delay time T), a multiplier 100b that multiplies the tap output of this delay element by a tap step gain, a register 100c that stores the tap gains C-1 to C0 to C + 1 of each multiplier 100b, and the output of each multiplier It is composed of an adder 100d for adding. On the other hand, the determiner 101 is a determiner that detects the amplitude of a signal from the equalized output Y of the equalizer and generates an expected value signal. The output aK of the determiner 101 and the equalized output YK are input to the subtractor 101a to generate an error signal eK (difference between the equalized output and the expected value), and the tap gain of the register 100c is set based on the error signal eK. .

In the tap gain correction method using the error signal eK, LMS (Least Mean Squre) method and MSE are generally used.
(Mean Square Error) method is used. The equation shown in FIG. 5B is used to update the tap coefficient in the MSE method.

Here, j is the order of taps, the (V + 1) th order of Cj on the left side is the jth tap gain at time V + 1, the (V) th order of Cj on the right side is the jth tap gain at time V, and K is The order of input, X _Kj is input, α is the step size, and aK is the expected value signal from the determiner.

The above-mentioned automatic equalizer is used to compensate for waveform distortion in data transmission. However, when a sudden change or disturbance occurs in data transmission for some reason,
It is known that in the automatic equalizer, the coefficient values of the automatic equalizer do not converge and the system may diverge. As an improvement to this, there is an automatic equalizer described in JP-A-56-17532. This publication is provided with a judgment circuit for detecting that the error amount of an expected value (ideal value) obtained from the output of the judgment device exceeds a certain value, and means for prohibiting the correction of the error amount by the output of this judgment circuit. This improves the divergence of the coefficient of the automatic equalizer due to the temporary disturbance of the transfer system.

[0008]

However, in the above-mentioned prior art, an input signal with a large amount of disturbance such as a reproduction signal in a magnetic recording apparatus, or a low S / N ratio when the input signal amplitude is reduced due to a medium defect. No consideration is given to the input signal. Therefore, according to the inventor of the present invention, in the above-described conventional technique, when an input signal of a disturbance such as speed fluctuation or noise jitter or dropout arrives,
It has been found that not only the improper equalization action is performed but also the proper equalization operation cannot be restored even after the disturbance or the dropout is stopped.
This problem will be described with reference to the waveform chart of FIG. FIG. 6 shows a case where the level of the input signal of the bit period T, the binary value 010 (the original level is “0” is low level and “1” is high level) is temporarily lowered (dropped out) due to the medium defect. 2 shows the operation of the equalizer. As shown in (b) and (c) of the figure, in the conventional method, the center tap C0 (for example, the binary data value "1") that should originally update the tap coefficient of the equalizer, is equalized to the expected value. Output equalization error eo
Is greater than a certain value, correction of the tap coefficient for this center tap C0 is prohibited. On the other hand, the tap coefficient (C-1, C + 1) other than the center tap is equal to the expected value. Since 1 and e + 1 are small, the tap coefficient is corrected. Therefore, since the amplitude of the data of the numerical value “1” is not corrected and the tap coefficient other than the center tap is corrected to perform the adaptation operation, the error amounts e−1 and e + 1 are updated by updating the tap coefficient other than the center tap. The equalization action is performed so as to reduce only the so-called slimming effect. Therefore, since the adaptive equalization operation is performed in the state where correct amplitude correction is not performed, the amplitude of the equalized output signal 5b in FIG. 9A is lower than that of the input signal 5a, and the equalized output signal 5b becomes equal depending on the length of the dropout. The converted output becomes zero. In addition, disturbance of the equalizer occurs due to an incorrect expected value when the amplitude of the equalized output decreases. Furthermore, the tap coefficient in the adaptive equalization operation at the center tap that is not fed back by the error cut function is an abnormal value, and the equalized output amplitude cannot be recovered even if the input amplitude after dropout becomes large. .

[0009] The occurrence of such a problem is, in short,
To determine whether to stop updating the tap coefficient,
This is because the error amount between the equalized output that does not correctly reflect the state of the input waveform and the expected value is used. In other words, once a large disturbance occurs in the input waveform, an error amount above a certain value is detected, and the updating is stopped, the equalization output and the expected value are deviated, and this deviance is further promoted and appears in the error amount. This is because the error amount does not correctly reflect the state of the amplitude of the input waveform, and the error amount remains largely deviated even after the disturbance ends. Therefore, in the present invention, a signal reflecting the state of the amplitude of the input waveform itself is used as much as possible, instead of using the conventional error amount to determine whether to stop updating the tap coefficient,
For example, the inventors have found that an adaptive equalization operation that responds correctly to an input signal and does not malfunction is performed by using the equalized output, the input signal itself, or their envelope waveforms.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and use a signal that reflects the amplitude state of the input signal waveform as much as possible to determine whether or not the tap coefficient can be updated. Accordingly, the adaptive equalizer does not malfunction even when the input signal has a large amount of disturbance or the dropped-out input signal, and a data signal reproducing device equipped with an adaptive equalizer that faithfully responds to the input signal is provided. It is in.

[0011]

To achieve the above object, the present invention provides an adaptive equalizer to which a data signal is input,
A discrimination circuit for obtaining an equalization error signal between an equalization output signal of the adaptive equalizer and an expected value, and input data by adjusting a tap coefficient of the adaptive equalizer according to the equalization error signal. In a data signal reproducing apparatus having an equalization control means for automatically adapting a signal waveform, a comparison circuit for comparing the amplitude of the input data signal or the amplitude of the equalized output signal with a predetermined value. , When the temporary decrease in amplitude of the input data signal or the equalized output signal is detected by the comparison result, the tap coefficient immediately before the decrease in amplitude is held by stopping the adaptive equalization operation of the adaptive equalizer. And an adaptive equalization operation stopping means for performing the same.

The present invention further includes an envelope creating circuit for creating an envelope value of the input data signal or the equalized output signal, and the comparison circuit is configured to compare the magnitudes of the envelope value and the predetermined value. You can also

The adaptive equalization operation stopping means may be configured to stop updating all the tap coefficient values in the adaptive equalizer, or other than the center tap in the adaptive equalizer. You may comprise so that update of only a tap coefficient value may be stopped.

Needless to say, the tap coefficient of the adaptive equalizer is restarted when the amplitude of the input data signal or the equalized output signal recovers to a predetermined amplitude or more.

[0015]

The operation based on the above configuration will be described.

According to the present invention, data signal reproduction using an adaptive equalizer for automatically adaptively equalizing an input data waveform by adjusting an equalization characteristic such as a tap coefficient according to an equalization error signal. In the device, the comparator monitors the amplitude state of the input data signal or the equalized output signal, and when this amplitude temporarily decreases (when the absolute value of this amplitude or the envelope value decreases below a predetermined value), Since the update of the tap coefficient of the adaptive equalizer is temporarily stopped and the coefficient value is held at the previous value, the normal adaptive equalization operation is continued when the input signal amplitude is large. When the input signal drops below a specified value due to the occurrence of a large dropout such as a medium defect, the adaptive equalizer operation is temporarily stopped to prevent the malfunction and disturbance of the adaptive equalizer. Door can be. In particular, whether or not the adaptive equalization operation can be stopped is not determined by looking at the equalization error signal amplitude as in the conventional case, but a signal having a waveform amplitude that reflects the amplitude waveform state of the input data signal as accurately as possible, for example, , The input data signal, the equalized output signal, or their envelope waveforms are checked, so that even if the adaptive equalization operation is temporarily stopped due to a temporary decrease in the input signal amplitude, the input data signal will exceed the specified value. Back to
The adaptive equalization operation by changing the tap coefficient of the adaptive equalizer is immediately restarted, and there is no possibility that the conventional equalizer cannot recover.

Further, when the temporary stop of the adaptive equalization operation is performed by stopping the tap coefficient update other than the center tap, only the center tap operates with respect to the input signal lowered to the outside of the allowable range such as dropout. Therefore, the amplitude can be corrected, and the adaptive equalization operation can be followed only for the input signal within the predetermined allowable range without following the adaptive equalization operation except for the center tap.

Further, information to be reproduced (input data signal)
Whether or not the adaptive operation can be stopped is controlled by the pattern
It is also possible to stop the adaptive equalization operation when an input of a specific pattern is detected. As a result, it is possible to prevent malfunction of the adaptive equalization operation.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

The present embodiment is a data reproducing apparatus for performing optimum adaptive equalization. FIG. 1 shows the configuration of a data reproducing system according to an embodiment (Embodiment 1) of the present invention. The illustrated configuration is provided in a data reproducing unit such as a magnetic recording / reproducing device.

In FIG. 1, 101 is an analog-digital converter (A / D converter), 102 is a variable equalization characteristic, and waveforms and frequency components of sampled input information from the analog-digital converter 101 are shown. An adaptive equalizer (adaptive waveform equalizer) that extracts such characteristics and performs adaptive equalization processing that dynamically adjusts the characteristics of the system according to the characteristics.
3 is a data value “1” or “0” from the output signal of the adaptive equalizer
Is a data discriminating circuit, and 104 is an equalizing error detecting circuit (adder) which functions as an error signal detecting means for outputting the difference between the equalizer output signal and the expected value signal generated from the data discriminator. 105, 106, 107, 108,
Reference numeral 109 is a gate circuit that switches whether the equalization error signal is fed back or not fed back by the comparator 134. Reference numeral 110 denotes a peak pulse detection circuit that generates a pulse at the peak value of the input waveform. For example, in the case of an input signal having a binary value "0" as a low level and a binary value "1" as a high level, the value "1" is A peak pulse detection signal is generated each time it arrives. Reference numeral 111 is a reference clock generation circuit for generating a clock signal whose phase is synchronized at the change point of the peak pulse, 11
Reference numeral 2 denotes an envelope value updating circuit for generating an envelope signal corresponding to the peak value of the signal (data value "1") from the output signal amplitude value of the equalizer 102, and 134 denotes the magnitude relationship between the envelope value and the predetermined value A. It is a comparison circuit for comparing.

Further, in the adaptive equalizer 102, 114
˜117 are delay circuits for delaying data (delay time T =
It has a 1-bit width) and includes a latch circuit and the like. 118-
Reference numeral 122 is a multiplication circuit, 123 to 127 are tap coefficient update circuits that determine each tap coefficient of the adaptive equalizer, and 128 is an addition circuit that sums the signals that have passed through the delay circuits 114 to 117 and the multiplication circuits 118 to 122. .

In the envelope value updating circuit 112, 113 is a register for holding the envelope value, 1
29 is a register that holds the equalized output, 130 is an absolute value circuit that takes the absolute value of the output of the register 129, 131 is the envelope value Venv that is the output of the register 113, and the equalized output signal that is the output of the absolute value circuit 130. The comparator 132 for comparing the amplitude with the absolute value is either an envelope value Venv, a value obtained by adding a fixed number UD thereto, or a value obtained by subtracting a fixed number DC from it, depending on the comparison result of the comparator 131. It is a selector that selects one of them.

With these circuits, the adaptive equalization circuit 102 is
At, according to the tap coefficient set inside,
A function for performing adaptive operation and a function for performing adaptive equalization, which receives the equalization error signal obtained for the signal output as a result of the adaptive operation, updates the tap coefficient and changes its characteristics, are configured. Will be realized.

The output Venv of the envelope value updating circuit 112, which is the output of the register 113, is triggered by the peak data signal (peak pulse signal) output from the peak detection circuit 110, and each time a peak pulse is detected, Absolute value Va of the equalized output signal of adaptive equalization circuit 102
It is updated to the value according to bs.

The envelope value Venv stored in the register 113 is the absolute value of the equalized output signal which is subjected to adaptive waveform processing after the input signal is A / D converted by the reference clock signal whose phase is synchronized with the peak data signal. Updated based on Vabs. If an initial value is input to the register 113 in advance, the appropriate envelope value Ven can be promptly input.
v can be generated. This envelope value Ven
The updating of v does not follow a rapid change in bit unit of the equalized output amplitude but follows a gradual change in signal amplitude due to a defect in the recording medium called dropout. Performs the following procedure, for example. (1) In the case of Venv (n-1) <Vabs (n) Venv (n) = Venv (n-1) + UD (2) In the case of Venv (n-1)> Vabs (n) Venv (n) = Venv (N-1) -DC (3) In the case of Venv (n-1) = Vabs (n) Venv (n) = Venv (n-1) where n is the order of data, UD is the envelope value addition constant, DC is an envelope value subtraction constant.

(1) shows the operation when the absolute value Vabs of the output amplitude of the equalizer 102 is larger than the envelope value Venv. In this case, first, the envelope value Ve
Addition constant UD is added to nv (n-1). When the result of one UD addition is less than Vabs (n), UD addition is repeated until the result of addition becomes equal to Vabs (n). The addition result is used as a new envelope value. (2) shows the operation when the absolute value Vabs of the equalized output is smaller than the envelope value Venv (n-1). In this case, first, the subtraction constant DC is subtracted from the envelope value Venv (n-1). The result of one DC subtraction is Vabs.
When (n) is exceeded, the subtraction result is Vabs.
DC subtraction is repeated until it becomes equal to (n). The result of the subtraction is the new envelope value. (3) is the envelope value Vens (n-1) and the absolute value Vab of the equalized output signal
The case where s is equal is shown. In this case, the envelope value Venv is not updated.

The above operation will be described with reference to FIGS. 1 and 2. 2A shows the output of the adder circuit 128 of FIG.
(B) represents the output of the register 113. In addition,
This is a digital value represented by amplitude. First, Venv (n-1) stored in the register 113 at the fall of the peak pulse signal from the peak detector 110.
Is output. The equalized output output from the adaptive equalizer 102 is a register 129 at the falling edge of the peak pulse signal.
Is output by the absolute value circuit 130,
Vabs (n) is obtained. Ve in the comparator 131
The magnitudes of nv (n-1) and Vabs are compared, and the selector 132 selects Venv (n-1), V according to the result.
Either env (n-1) + UC or Venv (n-1) -DC is selected, and the result is stored in the register 113. The data stored in the register 113 is Vabs.
(N) and the comparator 131 perform size comparison. Conditions (1), (2), (3) based on the result of the comparator 131
Is executed. When the next peak detection signal is received, the above calculation result is passed to the comparator 134 as the envelope value Venv (n). The comparator 134 compares the envelope value with a predetermined value (reference value) A, and the equalization error signal output from the error detector 104 is gated by the gate circuits 105 to 109 according to the output from the comparator 134. That is, FIG.
As described above, when the envelope value becomes smaller than the predetermined value A, the gate circuits 105 to 109 are closed, zero is output, the tap coefficient is not updated, and the previous value is held as it is.

When the envelope value is larger than the predetermined value A or equal to the predetermined value A, the gates 105 to 10
9 is opened and the same value as the equalization error signal is output.

Further, tap coefficient updating circuits 123 to 127 are provided.
Changes the equalization characteristic by an adaptive algorithm. In this case, during the period in which the gates 105 to 109 are closed and zero is output, the algorithm included in the tap coefficient updating circuits 123 to 127 is such that the output of the equalizer 102 is in a shape most suitable for the purpose. Since the judgment is made, the equalization characteristic is not changed.

Therefore, according to the data reproducing method of the present embodiment, the predetermined value A which is the maximum allowable range of the equalized output envelope such as the medium defect such as dropout, and the equalized output envelope generation circuit 112 output. By providing the comparator 134 for comparing the envelope values and the gates 105 to 109 that are opened / closed corresponding thereto, the update of the tap coefficient can be temporarily stopped only when the equalized output decreases. As a result, when the output amplitude of the adaptive equalizer decreases due to the A / D sampling error due to the reference clock phase error such as speed fluctuation and noise jitter, or the output amplitude of the adaptive equalizer decreases due to dropout. In this case, since the adaptive equalization operation is made to follow only the normal equalized output signal of the predetermined value A or more without causing the adaptive equalization operation to follow the decrease in the amplitude of the equalized output, the malfunction of the equalizer is caused. It is possible to prevent waveform disturbance due to. In particular, in this embodiment, the predetermined value A is compared with the envelope value Venv of the equalized output that correctly reflects the amplitude state of the input signal as an input of the comparator 134 that determines whether tap update is possible. , The tap coefficient updating is surely stopped in the dropout period, and the normal equalization operation is promptly performed when the dropout ends and the input signal amplitude is restored to a certain value or more.

FIG. 3 is a block diagram showing a data reproducing apparatus of another embodiment (embodiment 2) of the data reproducing system of the present invention, and FIG. 4 shows equalized output waveform envelope values in the adaptive equalizer of this embodiment. It is explanatory drawing which shows the relationship with a predetermined value.

The adaptive equalizer of this embodiment is, for example, an adaptive equalizer used in a magnetic recording device, and equalizer 102 for equalizing an input signal under a predetermined condition and equalizer 102. Tap coefficient update circuits 123 to 127 for controlling the conditions, and an adder 1 for calculating the output signal of the equalizer 102 and an expected value.
04, an envelope value updating circuit 112 that generates an envelope of the output signal of the equalizer 102, a comparator 134 that compares the output value of the envelope value updating circuit 112 with a predetermined value A, and a comparator 134. Gate 10 provided other than the center tap that opens and closes according to the state
5, 106, 108, and 109. The second embodiment is different from the first embodiment in that the center tap is not provided with a gate circuit, and when the envelope value falls below a predetermined value A which is an allowable range, the equalization error signal is center tapped. Gate circuits 105, 106, 108 other than
By gating at 109, only the adaptive operation other than the center tap is stopped, and only the amplitude value of the equalized output by the center tap is corrected.

That is, in this embodiment, the adder 1
The equalization error output from 04 is directly input to the tap coefficient updating circuit 125 of the center tap, and is also input to the tap coefficient updating circuits 123, 119, 121, 122 via the gate circuits 105, 106, 108, 109. Is entered. Then, in the tap coefficient updating circuits 123 to 127, the input signal Xj output from the A / D converter 101 is input.
And the equalization error signal eK output from the adder 104
Then, the adaptive equalization algorithm updates the tap coefficient in order to change the equalization characteristic.

On the other hand, the output of the equalizer 102 is input to the envelope value updating circuit 112, and the envelope value Venv corresponding to the equalized output is output. Envelope value V
The env is input to the comparator 134 and compared with the predetermined value A by the comparator 134. Then, the comparison result with the predetermined value A, that is, the output of the comparator 134 is the gate circuits 105, 106, 10 provided in addition to the center tap coefficient update.
It is input to 8,109.

Therefore, the output waveform of the equalizer 102 (output waveform of the adder circuit 128) and the envelope waveform of the output of the register 113 are as shown in 4a of FIG. 4 (a) and 4c of FIG. 4 (b), respectively. Become. In addition, 4b and 4d additionally show the case of FIG. 2 for comparison. The difference from FIG. 2 (difference between 4a and 4b, and difference between 4c and 4d) is the amount of increase due to not stopping the center tap. As shown in FIG. 4, the output of the comparator 134 is the envelope value 4c.
Error signal eK other than the center tap, the gate circuits 105, 1
The gates are turned off by 06, 108 and 109, and the updating of the tap coefficients of the tap coefficient circuits 123, 124, 126 and 127 is stopped.

On the other hand, the tap coefficient of the center tap is updated by the amplitude difference between the equalized output (data value "1") and the expected value. In this case, the adaptive equalizer generally has multipliers 118, 119, 12 other than the center tap.
The outputs from 1, 122 are used to change the equalization characteristic, and the output from the multiplier 120 from the center tap is equalized output amplitude value by the error signal with the expected value with respect to the output amplitude from the equalizer 102. Used to correct the.

Therefore, according to the adaptive equalizer of this embodiment,
When the envelope value Venv becomes smaller than the predetermined value A by the comparison result of the envelope value Venv and the predetermined value A which is the minimum allowable range and the gate circuit provided other than the center tap which opens and closes accordingly, The adaptive operation is stopped by stopping the updating of the tap coefficient by the conversion error signal. On the other hand, since the tap coefficient of the center tap is updated by the error signal, the equalized output amplitude can be corrected as shown by 4b in 4a of FIG. As a result, since the equalization characteristic can correct the equalization output amplitude without following the equalization output smaller than the minimum allowable range, it is possible to reduce the data discrimination error with respect to the reduction in the amplitude of the equalization output due to the dropout. .

In the above embodiment, the envelope value V
Although env is created from the output of the equalizer 102 (the output of the adder circuit 128), the A / D converter 1 before the equalizer 102 is generated.
It is also possible to create it from the output of 01.

In the above embodiment, the case where the invention is applied to the magnetic recording / reproducing apparatus is shown, but the invention can also be applied to other types of recording / reproducing apparatus such as an optical disk device and a transmission system.

[0041]

As described above in detail, according to the present invention, the amplitude of the input data signal or the equalized output signal is used to determine whether to update or stop the tap coefficient of the adaptive equalizer. Alternatively, a comparator for monitoring the magnitude relationship between the envelope value and the predetermined value is provided, and the adaptive equalization operation is temporarily stopped when the former value becomes a predetermined value or less based on the comparison result. Therefore, the normal adaptive equalization operation is continued when the input data signal amplitude is large, but the adaptive equalization operation by tap update is performed when the amplitude is extremely low due to large dropout such as medium defect, speed fluctuation, and jitter. It is possible to prevent an erroneous equalization operation from being temporarily stopped. In particular, the decision as to whether or not the adaptive stop is possible is not made based on the equalization error signal as in the conventional art, but an input data signal reflecting the amplitude waveform state of the input data signal, an equalized output signal or their envelope signals. However, even if the adaptive equalizer operation is stopped once, the tap coefficient updating operation of the adaptive equalizer will be restarted immediately if the input data signal returns to a predetermined value or more, resulting in the input of the adaptive equalizer. It is possible to obtain the effect that the followability to the data signal can be improved.

Further, by limiting the tap coefficient for stopping the adaptive equalizer to other than the center tap, dropout such as medium defect and A / D sampling error due to reference clock phase error such as speed fluctuation and noise jitter can be prevented. Even when the resulting reduction in the equalization amplitude of the adaptive equalizer falls below a predetermined level (predetermined value) in the maximum allowable range, the amplitude of the equalization output is corrected by the center tap, so When the digitized output amplitude is reduced, the effect of reducing the data discrimination error due to the reduced output amplitude can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment (embodiment 1) of a data reproducing apparatus using a control system of an adaptive equalizer of the present invention.

FIG. 2 is an explanatory diagram of adaptive equalization operation according to the first embodiment.

FIG. 3 is a block diagram showing a second embodiment (embodiment 2) of the data reproducing apparatus using the control system of the adaptive equalizer of the present invention.

FIG. 4 is an explanatory diagram of adaptive equalization operation according to the second embodiment.

FIG. 5 is a block diagram showing a conventional adaptive equalizer.

FIG. 6 is an explanatory diagram of an adaptive operation of a conventional adaptive equalizer.

[Explanation of symbols]

 101 A / D converter 102 Adaptive waveform equalizer 103 Data discriminator 104 Adder 105-109 Gate circuit 110 Peak detector 111 Reference clock generation circuit 112 Envelope value update circuit 113 Envelope value Venv holding register 114-117 Delay circuit 118 ˜122 Multiplier circuit 123 to 127 Tap coefficient update circuit 128 Adder circuit 129 Absolute value Vabs holding register 130 Absolute value circuit 131 Comparator 132 Selector 134 Comparator

Claims (5)

[Claims] 1. An adaptive equalizer to which a data signal is input,
A discrimination circuit for obtaining an equalization error signal between an equalization output signal of the adaptive equalizer and an expected value, and input data by adjusting a tap coefficient of the adaptive equalizer according to the equalization error signal. In a data signal reproducing apparatus having equalization control means for automatically adaptively equalizing a signal waveform, a comparison circuit for comparing the amplitude of the input data signal or the amplitude of the equalized output signal with a predetermined value. When a temporary amplitude reduction of the input data signal or the equalized output signal is detected by the comparison result, the tap coefficient immediately before the amplitude reduction is performed by stopping the adaptive equalization operation of the adaptive equalizer. A data signal reproducing apparatus comprising: an adaptive equalization operation stopping means for holding. 2. An envelope creating circuit for creating an envelope value of the input data signal or the equalized output signal, wherein the comparison circuit is configured to compare the magnitude of the envelope value with the predetermined value. The data signal reproducing apparatus according to claim 1, wherein 3. The data signal reproduction according to claim 1, wherein the adaptive equalization operation stopping means is configured to stop updating all tap coefficient values in the adaptive equalizer. apparatus. 4. The data according to claim 1, wherein the adaptive equalization operation stopping means is configured to stop updating tap coefficient values other than the center tap in the adaptive equalizer. Signal reproduction device. 5. The updating of the tap coefficient of the adaptive equalizer is restarted when the amplitude of the input data signal or the equalized output signal recovers to a predetermined amplitude or more. The data signal reproducing device according to any one of 1 to 4.