JP3184136B2 - Adaptive automatic equalizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adaptive automatic equalizer for automatically compensating for distortion and noise contained in a signal transmitted through a transmission line, equalizing the signal to an ideal signal, and outputting the signal. It relates to the improvement of.

[0002]

2. Description of the Related Art In general, adaptive equalization is a process of shaping a waveform of an input signal into an ideal output signal by a predetermined adaptive equalization algorithm. This is the process of reproducing the original signal into the original ideal signal.

FIG. 2 shows a configuration of a conventional adaptive automatic equalizer.
It is shown in FIG. In the figure, 1 is a transversal filter block, and 2 is an adaptive control block. In the transversal filter block 1, 11, 1
2, 13 and 1N are delay units, 21, 22, 23 and 2N
Is a multiplier, and 31, 32 and 3M are adders. Also,
In the adaptive control block 2, 41 is a determination unit, 51 is an error detection unit, and 61 is a coefficient correction unit.

[0004] The transversal filter block 1
Is a well-known FIR (Finite Impulse Response) filter, which convolves a plurality of data delayed by a predetermined time with respect to an input signal, and outputs the result.
That is, a signal containing distortion transmitted through the transmission path is input, the input signal is time-delayed by a plurality of delay units 11, 12, 13 and 1N by a predetermined time, and the data delayed each time is multiplied by each multiplication unit. The corresponding weighting coefficients are multiplied by 21, 22, 23 and 2N, and the multiplication results are sequentially added by a plurality of adders 31, 32 and 3M, and the final addition result is output to the outside.

The adaptive control block 2 sequentially changes the weighting coefficients used in the respective multipliers 21 to 2N, and these weighting coefficients themselves change over time. The reason why it is necessary to change the weighting factor sequentially and perform adaptive equalization is as follows.
In a system that records a plurality of signals at a high density (for example, a hard disk or a compact disk), if intersymbol interference from adjacent bits occurs, the intersymbol interference causes nonlinear distortion in a signal waveform, Is caused by the decrease in the amplitude. In the adaptive control block 2, the determination unit 41 compares the output signal of the transversal filter block 1 with a predetermined threshold, determines the expected value of the output signal, and outputs the expected value. The error detection unit 51 calculates an error between the output signal of the transversal filter block 1 and the expected value output from the determination unit 41.
The coefficient correction unit 61 calculates a weight coefficient of each of the multiplication units 21 to 2N of the transversal filter block 1 from the error value obtained by the error detection unit 51 and sequentially changes the weight coefficient. By repeating this operation, the output signal of the transversal filter block 1 approaches the expected value.

[0006]

However, in the adaptive automatic equalizer shown in FIG. 25, the transversal filter block 1 and the adaptive control block 2 are ideal, and accordingly, the updating of each weight coefficient is performed. Is performed without a time delay, and the output signal of the transversal filter block 1 converges to the expected value early.
1 to 2N, the addition units 31 to 3M, the determination unit 41, the error detection unit 51, and the coefficient correction unit 61 each have an operation delay amount. As a result, the weight coefficient is updated with the total value of these delay amounts as one cycle, that is, during the period of the total delay amount, it is necessary to use the same value of the weight coefficient, and converge to the expected value. Requires a long time, and the convergence is not so good.

On the other hand, it is possible for the coefficient correction unit 61 to calculate and update each weight coefficient for each signal that is continuously input. However, since the next weighting factor can be appropriately corrected only after the output signal of the transversal filter block 1 is obtained using the weighting factor updated last time, even if the weighting factor is successively updated for each successive signal, the transversal The output signal of the filter block 1 does not converge to the expected value, resulting in oscillation.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a multiplication unit, an addition unit, a determination unit, an error detection unit provided in a transversal filter block and an adaptive control block.
And a stable adaptive automatic equalizer that improves the convergence by converging the output signal of the transversal filter block 1 to an expected value in a short time without oscillation even if the coefficient correction unit has a delay amount. Is to provide.

[0009]

In order to achieve the above object, the present invention provides an adaptive automatic equalizer for adaptively equalizing an input signal by giving weighting coefficients to a plurality of multipliers. And a plurality of weighting factor holding units for storing weighting factors are provided for each of the multiplying units, and the weighting factors of these weighting factor holding units are each reduced by the amount of delay until each of the weighting factors is changed. By adopting a configuration in which these weighting factors are sequentially selected while changing the period, even if there is an amount of delay until the weighting factor is changed, the weighting factor is changed multiple times within the period of the delay amount. It will be changed to improve the convergence.

That is, in the adaptive automatic equalizer according to the first aspect of the present invention, a plurality of delay units for inputting a signal and time-delaying the input signal in order to equalize the input signal, and each of the delay units A plurality of multiplication units for multiplying the delay signal by a weighting factor,
A transversal filter including an addition unit that adds the multiplication results of the respective multiplication units; a determination unit that receives an output of the addition unit of the transversal filter and determines an expected value of the output; An error detection unit that detects an error between an output and an output of the determination unit; and a selection-type coefficient that receives an error output from the error detection unit and corrects a weight coefficient to be given to each of the multiplication units based on the error. An adaptive automatic equalizer including a correction unit, wherein the selection-type coefficient correction unit is provided in the same number as the number of the multiplication units, calculates correction values of the weighting coefficients, and multiplies the corrected weighting coefficients by a corresponding multiplication. A plurality of weighting factor holding units, each of which is provided with a plurality of weighting factor holding units, each time the correction value of the weighting factor is calculated, the plurality of weighting factor holding units. Select one Sequentially repeating the above, and while holding the plurality of corrected weighting factors in the plurality of weighting factor holding units, sequentially providing the held weighting factors to the corresponding multiplication units one by one. I do.

According to a second aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, the number of weight coefficient holding units provided in each of the coefficient changing units is equal to the number of the transversal filter, the determination unit, It is characterized in that the number corresponds to the total delay amount obtained by summing the respective delay amounts of the error detection unit.

According to a third aspect of the present invention, in the adaptive automatic equalizer according to the first or second aspect, the corrected weighting factor of each weighting factor holding unit includes the transversal filter, the determination unit, and the error. The total delay amount obtained by summing the delay amounts of the detection units is provided as a period to the corresponding multiplication unit.

According to a fourth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, the selective coefficient correction section comprises:
It is characterized in that a control signal for designating the required number of weight coefficient holding units is received, and the weight coefficient is corrected using the number of weight coefficient holding units specified by the control signal.

According to a fifth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, an error output from the error detection unit and an input signal of the transversal filter are input, and the error and the input signal are input. Has a delay amount detection unit that detects a delay time required until the output of the corrected weight coefficient, and the selection-type coefficient correction unit is configured based on the delay time detected by the delay amount detection unit. The number of required weight coefficient holding units is calculated, and the weight coefficient is corrected using the calculated number of weight coefficient holding units.

According to a sixth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, the adaptive automatic equalizer is opened upon receiving a control signal input from the outside, so that the error detecting section and the selective coefficient correcting section are connected to each other. A switch for disconnecting the connection is provided.

According to a seventh aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, a decision circuit which inputs an error output from the error detection section and compares the error with a set level, A switch is opened when the error is equal to or higher than a set level by a determination circuit, and disconnects the connection between the error detection unit and the selective coefficient correction unit.

According to an eighth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect of the present invention, an output of the transversal filter is input, and a determination circuit for comparing the amplitude of the output with a set level, A switch is opened by a circuit when the amplitude of the output is equal to or higher than a set level, and disconnects the connection between the error detection unit and the selective coefficient correction unit.

According to a ninth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, an error output from the error detecting unit is input, and the coefficient changing unit is operated in accordance with the magnitude of the error. The number of taps used for controlling the number of taps is provided.

According to a tenth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, a control signal is input from the outside, and the number of the coefficient changing units to be used is controlled based on the control signal. A change tap number control unit is provided.

According to an eleventh aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, a control signal is input from the outside, and the number of the coefficient changing units to be used based on the control signal, The number of taps to be changed and the number of weighting factors for controlling the number of the weighting factor holding units used in the coefficient changing unit to be used are provided.

According to a twelfth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, the plurality of coefficient changing units are arranged at a subsequent stage, and the corrected weighting factors from these coefficient changing units are provided. A counter for limiting the output to the multiplication unit to a predetermined number of times is provided.

The invention according to claim 13 is the invention according to claim 12.
In the adaptive automatic equalizer described above, the predetermined number of times of the counter is set by a control signal input from the outside, and each of the coefficient change units uses the weight coefficient holding unit based on the control signal. Is controlled.

According to a fourteenth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, an input signal of the transversal filter is received, and a signal-to-noise ratio of the input signal is measured. A signal-to-noise ratio measuring unit for controlling the number of coefficient changing units to be used according to the ratio is provided.

According to a fifteenth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, a type of a recording medium that receives an input signal of the transversal filter and stores the signal based on the input signal. And a data identification unit for controlling the number of coefficient changing units to be used based on the identification result.

According to a sixteenth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, an average value of an error output from the error detecting section is calculated, and a coefficient to be used is calculated based on the average value of the error. An average value calculation unit for controlling the number of change units is provided.

According to a seventeenth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, an average value of the weight coefficients output from each weight coefficient holding unit is calculated, and the average value of the weight coefficients corresponds to the average value. And a mean value calculating unit provided to the multiplying unit.

According to an eighteenth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, it is determined whether the weighting factor output from each weighting factor holding unit is within a range between a set upper limit value and a set lower limit value. A determination circuit that outputs a weighting coefficient within the range to a subsequent stage when the value is within the range, and calculates an average value of the outputs of the determination circuit. And an average value calculating unit for controlling the number.

According to a nineteenth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, there is provided a coefficient storage unit for storing the latest corrected weight coefficient output from each coefficient changing unit, The latest corrected weighting factor in the storage unit is
It is used at the start of the next operation.

According to a twentieth aspect of the present invention, in the adaptive automatic equalizer according to the first aspect, an averaging unit for calculating an average value of the weighting coefficients held in each weighting factor holding unit is provided.
When the change of the weight coefficient by the coefficient changing unit is stopped, an average value of the weight coefficient calculated by the averaging unit is output to the corresponding multiplying unit.

With the above configuration, in the adaptive automatic equalizer according to the first to twentieth aspects of the invention, the correction of the weighting factor applied to one multiplication unit will be described. Is provided with a plurality of weight coefficient holding units for storing the weight coefficients. In the coefficient changing unit, the weighting coefficient is changed a plurality of times within this delay time even if a predetermined delay time is required for changing the weighting coefficient due to the configuration of the adaptive automatic equalizer. Each time the weighting factor is changed, one of the plurality of weighting factor holding units is repeatedly selected. As a result, the weighting factor held in each weighting factor holding unit is changed by the weighting factor change. The required predetermined delay time is updated as one cycle. Therefore, when the multiplication is performed by the multiplication unit using the weight coefficient held in each coefficient change unit, the weight coefficient used for the multiplication is corrected using the error obtained by the error detection unit based on the multiplication. Therefore, the weight coefficient can be appropriately corrected and updated. Therefore, the output signal of the transversal filter block does not oscillate, but converges to the expected value in a short time, thereby improving the convergence.

In particular, in the adaptive automatic equalizer according to the fourth and fifth aspects, the number of weight coefficient holding units used in each tap coefficient changing unit of the selection coefficient correction unit can be adjusted. The versatility of the selection coefficient correction unit can be improved.

Further, in the adaptive automatic equalizer according to the present invention, the adaptive control is stopped in a situation where the output of the transversal filter block converges to an expected value by an external control signal, and low power consumption is achieved. Can be achieved.

Furthermore, in the adaptive automatic equalizer according to the seventh and eighth aspects, when the output of the transversal filter changes drastically greatly due to noise or the like, the adaptive control is temporarily stopped. Erroneous updating of the weighting factor will be prevented.

In addition, in the adaptive automatic equalizer according to the ninth and tenth aspects, when the precision of the adaptive control is not so required, the number of the multipliers whose weighting coefficients are updated is limited to a small number. Low power consumption can be achieved.

In addition, since the adaptive automatic equalizer according to the eleventh aspect has both the configuration of the fourth aspect and the configuration of the tenth aspect, it is possible to obtain an action combining the actions of the claims. .

Further, in the adaptive automatic equalizer according to the twelfth and thirteenth aspects, the weighting factor of the multiplying unit can be updated at intervals of the set number of clocks by the operation of the counter, and the power consumption can be reduced.

Further, in the adaptive automatic equalizer according to the present invention, when the signal-to-noise ratio of the input signal of the transversal filter is low, the number of the multipliers whose weighting coefficients are updated is set large, The output of the transversal filter can be converged to the expected value in a short time.

In addition, in the adaptive automatic equalizer according to the fifteenth aspect, since the type of the storage medium for storing the signal input to the transversal filter is identified by the data identification unit, the type is determined according to the type of the storage medium. The characteristics of the adaptive automatic equalizer can be changed, and the output of the transversal filter 1 can be made to converge to the ideal output value in a shorter time.

In addition, in the adaptive automatic equalizer according to the present invention, even when the output of the error detecting section temporarily changes greatly due to noise or the like, the output error is appropriately adjusted. Since the average value is averaged together with the error, the erroneous updating of the weight coefficient given to each multiplication unit is mitigated.

In the adaptive automatic equalizer according to the seventeenth aspect, even when the output of the error detecting section temporarily changes largely due to noise or the like, the average weighting section calculates the average weight coefficient. Since the calculation is performed, the erroneous updating of the weight coefficient given to the multiplication unit is reduced.

Further, in the adaptive automatic equalizer according to the eighteenth aspect, when the value of the weight coefficient exceeds the upper limit value or becomes lower than the lower limit value due to noise or the like, the weight coefficient is excluded. Since the average weight coefficient is calculated by the average value calculation unit,
The erroneous updating of the weight coefficient given to the multiplication unit is further reduced.

In addition, in the adaptive automatic equalizer according to the nineteenth aspect, at the start of the adaptive control, the weight coefficient immediately before the end of the previous operation is used as the initial value, so that the output of the transversal filter is ideal at an early stage. It converges to the output value and the convergence is improved.

In addition, in the adaptive automatic equalizer according to the twentieth aspect, immediately before the end of the adaptive control operation, a plurality of weighting factors updated within a predetermined period immediately before the end are added by the averaging unit, An average weight coefficient is calculated from the added value.
Therefore, even if the last weight coefficient updated just before the end is updated to an erroneous value due to noise or the like, at the start of the next adaptive control operation, the appropriate average weight coefficient is used as an initial time. Therefore, the output of the transversal filter converges to the ideal output value at an early stage, and the convergence is improved.

[0044]

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

(First Embodiment) FIG. 1 shows the entire configuration of an adaptive automatic equalizer. In the figure, 1 is a transversal filter block, and 2 is an adaptive control block.
In the transversal filter block 1,
11, 12, 1N-1, 1N are delay units, 21, 22, 2,
N-1, 2N are multiplication units, 71, 72, 7N-1, 7N are latch units, and 30 is a plurality of adders 301, 302, 3
It is an addition unit having 0M. Also, adaptive control block 2
In the figure, 41 is a determination unit, 51 is an error detection unit, 62 is a selective coefficient correction unit characteristic of the present invention, and as shown in detail in FIG. Coefficient change units 621 to 62N for each tap having a plurality of latch units (weight coefficient holding units) for storing weight coefficients given to 2N
Is arranged.

Transversal filter block 1
Is a FIR (Finite Impulse Response) filter similar to the conventional one, and each of the delay units 11 to 1N sequentially delays the input signal and outputs the delayed signal to the corresponding multiplication unit 21 to 2N. These multiplication units 21 to 2N
Multiplies the time-delayed signal by a weighting factor given from the adaptive control block 2. Adder 30
Sequentially adds the multiplication results of the multiplication units 21 to 2N,
The final addition result is output to the outside. Note that each of the multipliers 21 to 21
Latch sections 71, 7 arranged between 2N and adder section 30
2, 7N-1, 7N are for accurately outputting data even during high-speed operation.

In the adaptive control block 2, the determination section 41 compares the output of the transversal filter block 1 (the output of the adder 30M) with a predetermined threshold value.
The expected value of the output signal is determined and output. Error detector 5
1 detects an error between the output of the transversal filter block 1 and the expected value determined by the determination unit 41. The selection-type coefficient correction unit 62 changes the weight coefficient given to each of the multiplication units 21 to 2N of the transversal filter block 1 using the error value detected by the error detection unit 51.

The transversal filter block 1
Then, the multiplication units 21, 22, 2N-1, 2N, the latch unit 7
In 1, 72, 7N-1, 7N and the adder 30, a delay amount until signal output occurs. Also in the adaptive control block 62, the determination unit 41, the error detection unit 51, and the selection-type coefficient correction unit 62 generate a delay amount until the correction of the weight coefficient. In the conventional adaptive equalizer, since the delay amount is not considered ideally for the correction of the coefficient, when the delay amount as described above occurs, the correction of the erroneous weight coefficient is performed. The selective coefficient correction unit 62 of the present embodiment corrects the weight coefficient in consideration of the delay amount as described above.

FIG. 2 shows the internal configuration of the selective coefficient correction section 62. In the same figure, 620 is a latch unit, 621,
622 and 62N are tap 1 (multiplier 21), tap 2
(Multiplying unit 22) and a coefficient changing unit corresponding to tap N (multiplying unit 2N). The latch unit 620 converts the input signal to the transversal filter block 1 into the delay units 11 to 1 of the transversal filter block 1.
N, the signals are delayed in time, and the signals delayed in time correspond to the coefficient changing units 621 to 62N. The corresponding time-delayed signal from the latch unit 620 and the output (detection error) of the error detection unit 51 shown in FIG. 1 are input to the coefficient change units 621 to 62N of the taps. Based on this, the weighting factor given to the corresponding multiplication unit is changed.

The coefficient change units 621 and 62 for each of the taps
2, 62N have the same configuration. Tap 1 coefficient changing unit 6
FIG. 3 shows the internal configuration of 21. In the figure, 6210
621 is an initial value holding unit for storing an initial value of the weighting coefficient;
Reference numerals 1, 6212, and 621N denote a plurality of (N) latch units (weight coefficient holding units) that store and hold sequentially updated weighting factors, 621A denotes an adder, 621D denotes a latching unit, and 621.
M is a multiplier, and 621S1, 621S2, and 621S3 are selectors, respectively.

In the tap coefficient changing section of FIG.
21M multiplies the output of the latch unit 620 of FIG. 2 by the output of the error detection unit 51 of FIG. This multiplication result is latched by the latch unit 621D. The selector 621S1 initially selects an initial weighting factor of the initial value holding unit 6210, and thereafter sequentially selects updated weighting factors held in the plurality of latch units 6211 to 621N one by one. The adder 621A adds the multiplication result latched by the latch unit 621D to the weight coefficient selected by the selector 621S1, and newly updates the weight coefficient. Selector 6
21S2 sequentially selects the plurality of latch units 6211 to 621N one by one. Therefore, the new weight coefficient calculated by the adder 621A is stored and held in the latch unit selected by the selector 621S2. Selector 621
S3 sets the plurality of latch units 6211 to 621N to 1
1 are selected one by one from the top in the figure, and the weighting factors of the selected latch section are respectively assigned to the corresponding multiplication sections 21, 22,.
Output to N.

FIG. 4 shows an example in which the number of taps (the number of multipliers) of the transversal filter block 1 is three. FIG. 5 shows the configuration of the selective coefficient correction unit 62 in this case.
FIG. 6 shows the configurations of the tap coefficient changing units.

In FIG. 6, the amount of operation delay in the transversal filter block 1 (ie, the total amount of delays of the multiplication unit, the latch unit, and the addition unit) is determined by the number of stages of the latch unit provided in the transversal filter block 1. That is,
There are two stages: latch units 71 to 73 and latch unit 30D.
Further, the correction delay amount of the weight coefficient in the adaptive control block 2 (that is, the total amount of the delay amounts of the determination unit 41, the error detection unit 51, and the selective coefficient correction unit 62) is built in the error detection unit 51. A latch unit (not shown), a latch unit 621D built in the coefficient changing unit, and a latch unit (weight coefficient holding unit) 6
211 to 6215. Therefore, the number of latch units (weight coefficient holding units) to be provided in the tap coefficient changing unit is five.

FIG. 7 shows an operation timing chart of the adaptive automatic equalizer constituted by FIGS. 4, 5 and 6. In the figure, the outputs of the delay units 11, 12, and 13,
The outputs of the latch units 71, 72, 73, the output of the latch unit 30D, the output of the error detection unit 51, the inputs of the latch units (weight coefficient holding units) 6211 to 6215, the output of the selector 621S3 (that is, the output of the tap coefficient change unit) ). here
The output of the error detection unit 51 and each latch unit (weight coefficient holding
Part) for one clock between the input of 6211 to 6215
The delay is built into the coefficient change units 621 to 623 of each tap.
The delay of the latch unit 621D.

The following description focuses on the input signal including five distortions (in FIG. 7, the output of the delay unit is denoted by the symbol 〜) which is successively input to the transversal filter block 1. As shown in the figure, in the adaptive automatic equalizer, when each signal is input, the weighting coefficient calculated and updated based on each signal at the time when five clocks have elapsed from the input of each signal. Are output from the coefficient changing units 621 to 623 of the taps of the adaptive control block 2. That is,
The calculation delay amount of the weight coefficient in the adaptive automatic equalizer is 5 clocks. However, for example, the coefficient changing unit 62 of the multiplication unit 21
In 1, when the weight coefficient based on the signal is calculated and updated by the adder 621A, the weight coefficient is stored and held in the latch unit (weight coefficient holding unit) 6211. Next, when one clock elapses, the weight coefficient based on the signal is output to the selector 621S.
The weighting coefficient based on each signal is sequentially stored in the latch unit (weight coefficient holding unit) 6212 from the adder 621A in the latch unit (weight coefficient holding unit) 6212, and thereafter, every time one clock elapses. 6215. That is, the weight coefficient of each latch unit (weight coefficient holding unit) is changed every four clocks. The weight coefficients of these latch units are sequentially held in the latch unit and simultaneously selected by the selector 621S3 and provided to the multiplying unit 21. As a result, as can be seen from FIG. 7, when a signal five clocks after the signal (indicated by the symbol “′” in FIG. 7) is input, the weighting coefficient of the latch unit 6211 based on the signal is given to the multiplying unit 21. Similarly, at the time of inputting each of the signals 5 clocks after the signals (indicated by reference numerals 'to' in the figure), a weighting coefficient based on each of the signals is given to the multiplying unit 21. Accordingly, as can be seen from FIG. 7, while updating the weighting factor given from the coefficient changing unit to the multiplying unit for each clock, the time delay (5 clocks) required for calculating and updating the weighting factor is taken into consideration, and each weighting factor is taken into account. Can be corrected and updated appropriately, the output of the transversal filter block 1 can be converged to the expected value early, and the convergence can be improved.

As described above, a plurality of latch sections (weight coefficient holding sections) for storing and holding weight coefficients to be given to the multiplication sections are provided for each of the multiplication sections, and the coefficients stored and held therein are mutually clocked. These coefficients are successively shifted by one cycle (predetermined time) and updated each time the delay time required for coefficient correction elapses, and these coefficients are sequentially selected at the predetermined time intervals. An ideal output signal can be stably obtained without the output error of the equalizer diverging.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An adaptive automatic equalizer according to the embodiment will be described.

FIG. 8 is a diagram showing the configuration of the adaptive automatic equalizer according to this embodiment. In the figure, only the configuration of the selective coefficient correction unit 63 of the adaptive control block 2a differs from that of the first embodiment. That is, the selection coefficient correction unit 63 has a control terminal 101 to which a control signal is input. The control signal specifies a required number of latch units from a plurality of latch units (weight coefficient holding units) provided inside the selection coefficient correction unit 63 according to the amount of delay in calculating the weight coefficient. Selective coefficient correction unit 63
Controls three selectors 621S1 to 621S3 in the coefficient changing unit of FIGS. 2 and 3 showing its internal configuration.
Other configurations and basic operations are the same as those of the first embodiment. Therefore, the same portions are denoted by the same reference numerals and description thereof will be omitted.

Therefore, in the present embodiment, since the required number of latch units can be specified by the control signal, the internal structure of the transversal filter block 1 or the adaptive control block 2a differs and the delay required until the weight coefficient is updated. Even if the time is different, the adaptive control block 2a can be used for general purpose, and the transversal filter block 1a is used.
It is not necessary to manufacture an adaptive control block corresponding to these filter blocks for each internal configuration.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
An adaptive automatic equalizer according to the embodiment will be described.

FIG. 9 shows the internal configuration of the selective coefficient correction unit 64 provided inside the adaptive automatic equalizer according to the present embodiment. The feature of the selective coefficient correction unit 64 in the figure is that it further has a delay amount detection unit 81 in addition to the internal configuration of the selective coefficient correction unit 62 shown in FIG.

The delay amount detecting section 81 detects a delay amount required for updating the weighting coefficient based on two signals of the input signal of the transversal filter block 1 and the output of the error detecting section 51. The detection signal is input to the coefficient changing units 621 to 62N of each tap. Based on the input delay amount detection signal, the coefficient change units 621 to 62N of each tap select one of a plurality of latch units (weight coefficient holding units) provided therein according to the delay amount of the weight coefficient. Specify the required number of copies. The output of the error detection unit 51
Is the detected error amount and the transversal filter 1
Output signal. The delay amount detection section 81
An input signal of the transversal filter block 1;
Transversal output of the output from the error detection unit 51
Temporary judgment of the value of both signals with the output signal of filter 1 (coarse value
Is determined), and the amount of delay between the two signal values that have been provisionally determined is calculated.
Detected and outputs the amount of delay as a detection signal.

Therefore, also in the present embodiment, as in the second embodiment, there is an effect that the adaptive control block can be used for general purposes.

(Fourth Embodiment) As shown in FIG. 10, an adaptive automatic equalizer according to the present embodiment has a control in which a control signal is input to an adaptive control block 2b inside the adaptive automatic equalizer. A terminal 102 and a switch 103 controlled by the control signal are further arranged. The control signal is
Command the sequential adaptive control function to stop.

Therefore, the control signal is input from the outside to the control terminal 102, the switch 103 is opened, and the connection between the error detecting section 51 and the selective coefficient correcting section 62 is cut off. As a result, the operation of the adaptive control block 2b is turned off, and the function of adaptive control is stopped. Therefore, in a situation where the output of the transversal filter block 1 has converged to the expected value, or in a situation where there is no need for adaptive control, the adaptive control is stopped and
Low power consumption can be achieved.

(Fifth Embodiment) As shown in FIG. 11, an adaptive automatic equalizer according to the present embodiment includes a decision circuit 42 and a decision circuit 42 in an adaptive control block 2c inside the adaptive automatic equalizer.
A switch 103 for receiving the output of the determination circuit 42 is further provided. The determination circuit 42 determines the output level of the error detection unit 51, and when the output level exceeds a predetermined value, outputs a control signal for instructing the function of the adaptive control to sequentially stop to the switch 103, and opens the switch 103. Let
Thereby, the operation of the adaptive control block 2c is turned off, and the function of the adaptive control is stopped.

Even when the output of the transversal filter 1 suddenly changes greatly due to noise or the like and the output of the error detection unit 51 increases, if the weighting coefficient is changed by adaptive control, the desired weighting coefficient However, in the present embodiment, since the operation of the adaptive control is stopped by the determination circuit 42, the updating of the weight coefficient can be temporarily stopped, and the desired adaptive control can be performed. is there.

(Sixth Embodiment) As shown in FIG. 12, an adaptive automatic equalizer according to the present embodiment includes a decision circuit 43 and a decision circuit 43 in an adaptive control block 2d inside the adaptive automatic equalizer.
A switch 103 for receiving the output of the determination circuit 43 is provided. The determination circuit 43 determines the output level of the transversal filter 1, and when the output level becomes equal to or higher than a predetermined value, outputs a control signal for instructing the stop of the adaptive control function to the switch 103, and opens the switch 103. Then, the operation of the adaptive control block 2d is turned off. When the output level of the transversal filter 1 becomes lower than the predetermined value, the switch 103 is closed and the adaptive control is restarted.

Therefore, in the present embodiment, when the output of the transversal filter 1 sharply changes greatly due to noise or the like, the operation of the adaptive control is stopped by the determination circuit 43 and the weighting is temporarily stopped. It is possible to stop updating the coefficients and perform desired adaptive control.

(Seventh Embodiment) As shown in FIG. 13, an adaptive automatic equalizer according to the present embodiment includes a tap number control section 9 in an adaptive control block 2e inside the adaptive automatic equalizer.
1 is arranged. The tap number control unit 91 receives the output of the error detection unit 51 and outputs a control signal to increase the number of multipliers for updating the weight coefficient when the output level is high and to decrease the number when the output level is low. Output to the selection coefficient correction unit 62.

Therefore, when the error output from the error detection unit 51 is small, that is, when the precision of the adaptive control is not so required, the number of the multipliers whose weighting coefficients are updated is limited to a small number. Low power consumption can be achieved.

(Eighth Embodiment) In this embodiment,
As shown in FIG. 14, in the selection-type coefficient correction unit 65,
The number of multipliers for updating the weight coefficient is controlled using the external control signal. That is, in FIG. 14, a control signal is externally input to the changed tap number control unit 111 via the control terminal 104. When receiving the external signal, the control unit 111 controls the tap coefficient changing unit 6 inside the selection-type coefficient correction unit 65.
The number to be used is controlled among 51, 652 to 65N. The limitation of the number is performed, for example, by cutting off the power supply line connected to the unused tap coefficient changing unit with a switch or the like. The tap coefficient changing unit to be used is, for example, the left and right symmetrical ones of the plurality of arranged tap coefficient changing units from the one located at the center. Therefore, the power consumption can be reduced by the number of times that the tap coefficient changing unit is not used.

(Ninth Embodiment) This embodiment is a combination of the second and eighth embodiments. That is, as shown in FIG. 15, in the selective coefficient correction unit 66, the number of changed taps and the number of latch units (weight coefficient holding units) 121 that receive an external signal via the control terminal 105 are controlled.
Are arranged separately. When receiving the external signal, the number control section 121 adjusts the number of tap coefficient changing sections to be used and uses the latch section (weight coefficient holding section) provided in each of the tap coefficient changing sections to be used. Adjust the number. Therefore, the effects of both the second and eighth embodiments can be obtained.

(Tenth Embodiment) In the present embodiment, as shown in FIG. 16, counters 1311 to 131N are arranged at the subsequent stage of the coefficient changing unit of each tap in the selective coefficient correction unit 67. I do. Each of these counters calculates the weight coefficient from the coefficient change unit of the previous tap.
Transversal filter block as input
Clocks (not shown) input to the first latch units 71 to 7N.
As input the same clock and not), counted the input clock, at a set value, first coefficient change unit of the preceding stage of the tap outputs (i.e., selection-type coefficient correcting unit 6 the weighting factor)
7 is output to the corresponding multiplier.

Therefore, in the present embodiment, when the precision of adaptive control is not so required, the weighting coefficient of the multiplier can be updated at intervals of the set number of clocks instead of every clock, thereby reducing power consumption. Can be.

(Eleventh Embodiment) This embodiment is directed to
This is an improvement on the tenth embodiment. That is,
In the selection-type coefficient correction unit 68 shown in FIG. 17, the coefficient change units 671 to 67 of the respective taps from the outside via the control terminal 106.
A command value for the number of internal latch units (weight coefficient holding units) is input to N, and a set value can be input to each of the counters 1311 to 131N. Therefore, power consumption can be reduced as in the ninth and tenth embodiments.

(Twelfth Embodiment) In this embodiment, the signal-to-noise ratio of the input signal to the transversal filter 1 changes according to the data recording / reproducing characteristics, noise, and the like. The characteristics of the adaptive equalizer are changed according to the noise ratio. That is, as shown in FIG. 18, the signal-to-noise ratio measuring unit 141 is arranged in the selective coefficient correcting unit 67. The measuring unit 141 measures the signal-to-noise ratio of the input signal to the transversal filter 1, and when the signal-to-noise ratio is good, the tap coefficient changing units 691 and 69
The number of 2-69N used is small, and if it is bad, many are set.

Therefore, in the present embodiment, even when the signal-to-noise ratio of the input signal to the transversal filter 1 is poor, the number of the multipliers 21 to 2N whose weighting coefficients are updated can be increased. In addition, the output of the transversal filter 1 can be made to converge to the expected value in a short time, and when the signal-to-noise ratio is good, the number of operating tap coefficient changing units is reduced to reduce power consumption. Can be planned.

(Thirteenth Embodiment) In the present embodiment, as shown in FIG.
A data identification unit 151 that receives an input signal to the input unit is arranged.
The data identification unit 151 identifies the level value and pattern of the input signal to the transversal filter 1, identifies a recording medium storing the input signal, for example, a hard disk or a compact disk, and determines the identification result. Accordingly, the coefficient changing units 6101 and 6102 of taps to be used.
610N is controlled.

A recording medium for recording / reproducing data has various data reproduction characteristics depending on its type. In the present embodiment, the transversal filter 1 is used for the recording medium.
, The type of the storage medium can be identified based on the signal output to the adaptive equalizer, and the characteristics of the adaptive equalizer can be changed from the identification result, so that the output of the transversal filter 1 converges to the ideal output value in a shorter time. be able to.

(Fourteenth Embodiment) In the fourteenth embodiment, as shown in FIG. 20, in the selection-type coefficient correction section 611, the average value calculation section 161 is arranged in front of the tap coefficient change sections 6111 to 611N. I do. This average value calculation unit 16
1 averages the output of the error detection unit 51 within a predetermined time immediately before the input of the clock for each clock. The predetermined interval may be, for example, all tap coefficient change units 6111 to
This is the time until the sequential output of the weighting coefficients from 611N completes one cycle. The average error output from the average value calculation unit 161 is input to the coefficient change units 6111 to 611N of each tap, and is used for updating the weight coefficient.

Therefore, in the present embodiment, even if the output of the error detecting section 51 temporarily changes largely due to noise or the like, the erroneous output is not used by itself, but is used for a predetermined time. Since the average value is obtained within the range, it is possible to mitigate that the weight coefficient given to each multiplication unit is updated erroneously.

(Fifteenth Embodiment) In the fifteenth embodiment, as shown in FIG. 21, the coefficient changing section 612 of the tap L (each value from L = 1 to N) in the selective coefficient correction section has The average value calculation unit 162 is arranged at the subsequent stage of the selector 621S3. The average value calculating section 162 averages the outputs of the tap coefficient changing sections 6211 to 621N within a predetermined time immediately before the input of the clock for each clock. The predetermined interval is determined, for example, by all tap coefficient changing units 6211.
This is the time until the sequential output of the weighting coefficients from # to 621N makes one cycle. The average weight coefficient output from the average value calculation unit 162 is provided to a corresponding multiplier.

Therefore, in the present embodiment, similarly to the fourteenth embodiment, the error detection unit 5
Even when the output of 1 is largely changed temporarily, it is possible to mitigate the erroneous updating of the weight coefficient given to each multiplier.

(Sixteenth Embodiment) The present embodiment is a
This is an improvement on the fifteenth embodiment. That is,
As shown in FIG. 22, in the coefficient changing unit 613 of the tap L, the determination circuit 44 is arranged at a stage preceding the average value calculating unit 162. The determination circuit 44 determines whether the value of the weight coefficient output from the selector 621S3 is between the upper limit and the lower limit. The upper limit value and the lower limit value are set in the determination circuit 44 in advance. When the value of the weight coefficient output from the selector 621S3 is between the upper limit value and the lower limit value, the weight coefficient is output to the average value calculation unit 162 via the determination circuit 44, but exceeds the upper limit value. Alternatively, if the value is less than the lower limit value, the output to the average value calculating unit 162 is
Forbidden by 4.

If the value of the weighting coefficient exceeds the upper limit or is lower than the lower limit, the weighting coefficient is considered to be a result of being erroneously updated due to noise or the like. It is not a target of the averaging in the calculation unit 162. Therefore, in the present embodiment, it is possible to further ease the update of the erroneous weight coefficient.

(Seventeenth Embodiment) In the present embodiment, as shown in FIG.
In, a coefficient storage unit 171 is provided instead of the initial value holding unit that holds the initial weight coefficient. This coefficient storage unit 1
Reference numeral 71 sequentially stores the updated weight coefficients output from the selector 621S3. The coefficient storage unit 171 is configured by a storage element such as a flash memory that can hold the value of the weight coefficient even after the power is turned off.

Therefore, in this embodiment, when the power is turned on,
Alternatively, when the operation of the adaptive automatic equalizer is restarted, the coefficient storage unit 1
71, that is, the final weighting factor value at the time of the previous adaptive control operation is the transversal filter block 1
Becomes the initial value of the weight coefficient given to the multiplication unit, so that the weight coefficient at the start or restart of the adaptive control becomes appropriate, and the output of the transversal filter 1 can converge to the ideal output value early. The convergence can be further improved.

(Eighteenth Embodiment) In this embodiment, as shown in FIG.
In, an averaging unit 181 is arranged. The averaging unit 181 receives outputs of a plurality of latch units (weight coefficient holding units) 6211 and 6212 to 621N provided for each clock, adds, averages, and calculates an average weight coefficient. The average weight coefficient is output to selector 621S3.

When a storage medium such as a hard disk receives data or reproduces data and the adaptive automatic equalizer is operating, and only the adaptive control block is turned off according to the application, Is stopped, and only the transversal filter block 1 is switched to the adaptive control block 2
In the case of operating with a fixed value weight coefficient given from the above, if the updated final weight coefficient immediately before the turning off of the adaptive control block is updated to an incorrect value due to noise or the like,
The output of the transversal filter block 1 using the wrong weight coefficient does not converge to the expected value. However, in the present embodiment, when only the adaptive control block 2 is turned off, the average weight coefficient calculated by the averaging unit 181 is used as the weight coefficient given to the transversal filter block 1, so that the transversal filter block 1 Can be made to converge to the expected value in a short time.

[0091]

As described above, according to the adaptive automatic equalizer according to the first to twentieth aspects of the present invention, even if it takes a predetermined delay time to change the weight coefficient due to its configuration, Since the weighting factors can be changed a plurality of times within this delay time, these weighting factors can be appropriately corrected and updated, each with a predetermined delay time required for changing the weighting factor as one cycle.
The output signal of the transversal filter block can be converged to the expected value in a short time without oscillating the output signal, and the convergence can be improved.

In particular, according to the adaptive automatic equalizer of the fourth and fifth aspects, the versatility of the selective coefficient correction unit can be enhanced.

According to the adaptive automatic equalizer of the sixth aspect, in a situation where the output of the transversal filter block has converged to an expected value, the adaptive control is stopped to reduce power consumption. it can.

Further, according to the adaptive automatic equalizer according to the seventh and eighth aspects, when the output of the transversal filter suddenly changes greatly due to noise or the like, the adaptive control is temporarily stopped. Thus, erroneous updating of the weight coefficient can be prevented.

In addition, according to the adaptive automatic equalizer according to the ninth and tenth aspects, when the precision of the adaptive control is not so required, the number of the multipliers whose weighting coefficients are updated is limited to a small number. It is possible to reduce power consumption.

In addition, according to the adaptive automatic equalizer according to the eleventh aspect, since the configuration according to the fourth aspect and the configuration according to the tenth aspect are both provided, an operation combining the actions of these claims can be obtained. can get.

Further, according to the adaptive automatic equalizer of the twelfth and thirteenth aspects, the weighting factor of the multiplying unit can be updated at intervals of the set number of clocks by the operation of the counter, and the power consumption can be reduced.

Further, according to the adaptive automatic equalizer of the present invention, when the signal-to-noise ratio of the input signal of the transversal filter is poor, the number of multiplication units whose weighting coefficients are updated can be set large. Thus, the output of the transversal filter can be converged to the expected value in a short time.

In addition, according to the adaptive automatic equalizer of the fifteenth aspect, the type of the storage medium for storing the signal input to the transversal filter is identified by the data identification unit. Accordingly, the characteristics of the adaptive automatic equalizer can be changed, and convergence can be improved.

[0100] In addition to the above, the sixteenth to eighteenth aspects of the invention are described below.
According to the adaptive automatic equalizer described above, even when noise or the like occurs, it is possible to effectively reduce the possibility that the weight coefficient given to each multiplier is erroneously updated.

According to the adaptive automatic equalizer according to the nineteenth and twentieth aspects, at the start of the next adaptive control,
Using an appropriate weighting coefficient immediately before the end of the previous operation as an initial value, the output of the transversal filter can be quickly converged to the ideal output value, and convergence can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an adaptive automatic equalizer according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an internal configuration of a selective coefficient correction unit according to the embodiment.

FIG. 3 is a diagram showing an internal configuration of a tap coefficient changing unit in the embodiment.

FIG. 4 is a diagram showing an overall configuration of an adaptive automatic equalizer in the embodiment when the number of taps is three.

FIG. 5 is a diagram showing an internal configuration of the selection type coefficient correction unit.

FIG. 6 is a diagram showing an internal configuration of a coefficient changing unit of the tap.

FIG. 7 is a diagram showing a timing chart in the embodiment.

FIG. 8 is a diagram showing an overall configuration of an adaptive automatic equalizer according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to a third embodiment of the present invention.

FIG. 10 is a diagram illustrating an internal configuration of an adaptive control block according to a fourth embodiment of the present invention.

FIG. 11 is a diagram illustrating an internal configuration of an adaptive control block according to a fifth embodiment of the present invention.

FIG. 12 is a diagram illustrating an internal configuration of an adaptive control block according to a sixth embodiment of the present invention.

FIG. 13 is a diagram illustrating an internal configuration of an adaptive control block according to a seventh embodiment of the present invention.

FIG. 14 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to an eighth embodiment of the present invention.

FIG. 15 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to a ninth embodiment of the present invention.

FIG. 16 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to a tenth embodiment of the present invention.

FIG. 17 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to an eleventh embodiment of the present invention.

FIG. 18 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to a twelfth embodiment of the present invention.

FIG. 19 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to a thirteenth embodiment of the present invention.

FIG. 20 is a diagram illustrating an internal configuration of a selective coefficient correction unit according to a fourteenth embodiment of the present invention.

FIG. 21 is a diagram illustrating an internal configuration of a tap coefficient changing unit according to a fifteenth embodiment of the present invention.

FIG. 22 is a diagram illustrating an internal configuration of a tap coefficient changing unit according to the sixteenth embodiment of the present invention.

FIG. 23 is a diagram illustrating an internal configuration of a tap coefficient changing unit according to a seventeenth embodiment of the present invention.

FIG. 24 is a diagram illustrating an internal configuration of a tap coefficient changing unit according to the eighteenth embodiment of the present invention.

FIG. 25 is a diagram showing an entire configuration of a conventional adaptive automatic equalizer.

[Explanation of symbols]

1 Transversal filter block 2 Adaptive control block 11-1N Delay unit 21-2N, 621M Multiplication unit 30-3M Addition unit 621A Adder 41-44 Judgment unit 51 Error detection unit 62-69,610,611 Selection-type coefficient correction unit 621-62N, 651-65N, 661-66N, 671-67N, 691-69N, 6101
Up to 610N, 6111 to 611N Tap coefficient change unit 6211 to 621N Latch unit (weight coefficient holding unit) 621S1 to 621S3 Selector 81 Delay amount detection unit 91 Tap number control unit 101,102,104 Control terminal 103 Switch 111 Change tap number control unit 121 Change tap Number and latch number control section 1311 to 131N counter 141 Signal-to-noise ratio measurement section 151 Data identification section 161,162 Average value calculation section 171 Coefficient storage section 181 Addition and averaging section

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Hamada 1006 Kazuma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) H04B 3/04 -3/18 H04B 7/005

Claims (20)

(57) [Claims] A plurality of delay units for inputting a signal and delaying the input signal in order to equalize the input signal;
A plurality of multiplying units for multiplying the delay signal of each of the delay units by a weighting coefficient, and a transversal filter including an adding unit for adding the multiplication result of each of the multiplying units;
A determining unit that determines an expected value of the output; an error detecting unit that detects an error between an output of the transversal filter and an output of the determining unit; and an error output from the error detecting unit. And a selection coefficient correction unit that corrects a weight coefficient given to each of the multiplication units based on the number of the selection coefficient correction units. A coefficient change unit that calculates a correction value of the coefficient and provides the corrected weight coefficient to a corresponding multiplication unit; each of the coefficient change units includes a plurality of weight coefficient holding units; Each time the correction value is calculated, the selection of one of the plurality of weighting factor holding units is sequentially repeated, and the plurality of weighting factor holding units are held while the plurality of corrected weighting factors are held in the plurality of weighting factor holding units. Weighted coefficients sequentially Adaptive automatic equalizer, characterized by providing to the multiplier the number increments corresponding. 2. The number of weighting factor holding units provided in each of the coefficient changing units is a number corresponding to a total delay amount obtained by adding up the respective delay amounts of the transversal filter, the determination unit, and the error detection unit. The adaptive automatic equalizer according to claim 1, wherein: 3. The corrected weighting factor of each weighting factor holding unit corresponds to a corresponding multiplication unit with a total delay amount obtained by summing the delay amounts of the transversal filter, the determination unit, and the error detection unit as one cycle. The adaptive automatic equalizer according to claim 1 or 2, wherein 4. The selective coefficient correction section receives a control signal specifying a required number of weight coefficient storage sections, and corrects the weight coefficient using the number of weight coefficient storage sections specified by the control signal. The adaptive automatic equalizer according to claim 1, wherein: 5. An error output from the error detection unit and an input signal of the transversal filter are input, and a delay time required for outputting the corrected weight coefficient is detected based on the error and the input signal. The selection-type coefficient correction unit calculates the number of required weight coefficient holding units based on the delay time detected by the delay amount detection unit, and calculates the number of the calculated number. 2. The adaptive automatic equalizer according to claim 1, wherein the weight coefficient is corrected using a weight coefficient holding unit. 6. The adaptive automatic control according to claim 1, further comprising a switch that opens upon receiving a control signal input from the outside and disconnects the error detection unit and the selective coefficient correction unit. Equalizer. 7. A determination circuit for inputting an error output from the error detection unit and comparing the error with a set level, wherein the determination circuit opens when the error is equal to or higher than a set level, and opens the error detection unit. 2. The adaptive automatic equalizer according to claim 1, further comprising a switch for disconnecting the selection type coefficient correction unit from the selection type coefficient correction unit. 8. A determination circuit for receiving an output of the transversal filter and comparing the amplitude of the output with a set level, wherein the determination circuit opens when the amplitude of the output is equal to or greater than a set level to detect the error. 2. The adaptive automatic equalizer according to claim 1, further comprising a switch for disconnecting a connection between the unit and the selective coefficient correction unit. 9. A tap number control unit for receiving an error output from the error detection unit and controlling the number of the coefficient change units to be used according to the magnitude of the error. The adaptive automatic equalizer according to claim 1. 10. The adaptation according to claim 1, further comprising a change tap number control unit that receives a control signal from outside and controls the number of the coefficient change units to be used based on the control signal. Automatic equalizer. 11. A change tap for inputting a control signal from the outside and controlling the number of the coefficient changing units used and the number of the weight coefficient holding units used in the used coefficient changing unit based on the control signal. 2. The adaptive automatic equalizer according to claim 1, further comprising a number control unit for the number and the weight coefficient. 12. A counter disposed at a stage subsequent to the plurality of coefficient change units, and limiting the output of the corrected weight coefficients from these coefficient change units to the multiplication unit to a predetermined number of times. The adaptive automatic equalizer according to claim 1, wherein: 13. The predetermined number of times of the counter is set by a control signal input from the outside, and the number of the coefficient changing units that use the weight coefficient holding unit is controlled based on the control signal. 13. The adaptive automatic equalizer according to claim 12, wherein: 14. A signal-to-noise ratio measuring unit that receives an input signal of the transversal filter, measures a signal-to-noise ratio of the input signal, and controls the number of coefficient changing units to be used based on the signal-to-noise ratio. The adaptive automatic equalizer according to claim 1, further comprising: 15. An input signal of the transversal filter is received, a type of a recording medium storing the signal is identified based on the input signal, and the number of coefficient changing units to be used is controlled based on the identification result. The adaptive automatic equalizer according to claim 1, further comprising a data identification unit. 16. An average value calculation unit for calculating an average value of errors output from the error detection unit and controlling the number of coefficient changing units to be used based on the average value of the errors. The adaptive automatic equalizer according to claim 1. 17. An apparatus for calculating an average value of weighting factors output from each weighting factor holding unit, the average value calculating unit providing the average value of the weighting factor to a corresponding multiplying unit. Item 10. An adaptive automatic equalizer according to Item 1. 18. It is determined whether a weighting factor output from each weighting factor holding unit is within a range between a set upper limit and a set lower limit, and when the weighting factor is within the range, the weighting factor within the range is determined. A determination circuit that outputs to a subsequent stage; and an average value calculation unit that calculates an average value of outputs of the determination circuit and controls the number of coefficient change units to be used based on the average value. 2. The adaptive automatic equalizer according to 1. 19. A coefficient storage unit for storing a latest corrected weight coefficient output from each coefficient change unit, wherein the latest corrected weight coefficient in the coefficient storage unit is used at the start of the next operation. 2. The adaptive automatic equalizer according to claim 1, wherein: 20. An averaging unit for calculating an average value of the weighting factors held in each weighting factor holding unit, and when the change of the weighting factor is stopped by the coefficient changing unit, the averaging unit calculates the average value. 2. The average value of the weighting factors is output to the corresponding multiplication unit.
The adaptive automatic equalizer as described.