JPH03100971A - Automatic equalizer - Google Patents

Abstract

PURPOSE:To efficiently converge a property parameter to an optimum value without fail by providing an error detecting means, initial parameter setting means and property parameter control means. CONSTITUTION:An automatic equalizer 10 applies an initial parameter to an equalizer 5, which property parameter is freely made variable, by an initial parameter set part 13 and variably controls the property parameter by a property parameter control part 14. Concerning measuring points to which plural property parameters set in advance are correspondent, the initial parameter set part 14 successively detects the output error rate of the equalizer 5 by an error rate detection part 12, calculates the measuring point of the minimum error rate and applies this measuring point to the equalizer 5 as the property parameter. The control part 14 changes the property parameter of the equalizer 5 in a prescribed range and repeatedly executes control operation based on the degree of a change in the signal error rate of an output from the equalizer 5 to be detected by the detection part 12 so as to variably control the property parameter of the equalizer 5 in a direction where the signal error rate is made small.

Description

[Detailed Description of the Invention] A. Industrial Field of Application The present invention relates to an automatic etc. that automatically controls the characteristic parameters of an equalizer used in a transmission circuit such as a recording/reproducing device or a communication device. Regarding flower vases.

B. Summary of the Invention The present invention provides an automatic equalizer that automatically controls the characteristic parameters of an equalizer used in a transmission circuit such as a recording/reproducing device or a communication device. For the same flower vase, the output signal error rate is sequentially detected for each measurement point corresponding to a plurality of preset characteristic parameters to find the measurement point with the minimum error rate, and the characteristic parameters of this measurement point are used as the initial parameters. After performing the setting operation of initial parameters given to the equalizer, changing the characteristic parameters of the equalizer within a predetermined range,
Based on the degree of change in the signal error rate detected by the error rate detection means, the above-mentioned etc. This is the realization of an automatic equalizer that can efficiently and optimally control the characteristic parameters of the equalizer.

C. Conventional Technology In general, in transmission circuits such as recording and reproducing devices and communication devices, in order to reduce distortion of transmitted analog signals and errors in transmitted digital data, equalizer characteristics suitable for the transmission characteristics are applied to the transmitted analog signals and to reduce errors in transmitted digital data. For example, in a magnetic recording/reproducing device such as an audio tape recorder or a video tape recorder, a vase is used to transmit digital data. By providing
The recording density of the magnetic tape in the recording system can be increased.

Conventionally, the characteristics of flower vases have been properly adjusted at the time of product shipment and fixed in that state.

D Problems to be Solved by the Invention By the way, in a magnetic recording and reproducing device, the reproducing system may change due to various factors such as variations in the characteristics of the magnetic recording medium and magnetic head used, changes in temperature and humidity, changes over time, etc.
frequency characteristics fluctuate.

Therefore, sufficient reliability cannot be obtained by using a conventional equalizer with fixed equalizer characteristics.
If the equalizer characteristics are adjusted to have a margin in consideration of the fluctuations in the frequency characteristics of the reproduction system, the recording density will be reduced by the margin.

In order to eliminate such drawbacks, the applicant of the present application, in Japanese Patent Application No. 1-60416, changed the characteristic parameters of the flower vase, and based on the degree of change in the signal error rate of the output in response to this change. previously proposed an automatic equalizer in which the characteristic parameters of the equalizer are controlled to converge to optimal values.

However, in such an automatic equalizer, if the initial value and the convergence value of the characteristic parameter of the equal flower are far apart, a long convergence time is required. In addition, within the multidimensional space where the values of the characteristic parameters can take, there exists a spatial region in which the signal error rate of the output of the isoflower is constant, that is, the change in the signal error rate is "0", and this spatial region is defined by the characteristic parameters described above. If a small change region is included, it becomes impossible to converge the above-mentioned characteristic parameters to the optimal value. As shown in the figure, the area where the signal error rate of the output of the iso-vase is constant at ``bi'' is indicated by diagonal lines in the two-dimensional plane where the values of the characteristic parameters C, ,C, of the iso-vase can take. Even if the above signal error rate is detected at each measurement point P, ,P, ,P, ,P, where the characteristic parameters in this region are changed, the change in the above signal error rate are all “0”
”, it is not possible to control the characteristic parameters so as to bring them closer to the optimum values.

Therefore, in view of the problems in automatic equalizers, the present invention makes it possible to efficiently and reliably converge characteristic parameters to optimal values, and to provide optimal equalizer characteristics to input signals. The purpose is to provide an automatic equalizer.

Means for Solving the BH Problem In order to achieve the above-mentioned object, the automatic equalizer according to the present invention includes an equalizer whose characteristic parameters are freely variable and a signal error rate of the output of the equalizer. The error rate detection means sequentially detects the signal error rate of the output of the equalizer for each measurement point corresponding to a plurality of preset characteristic parameters, and detects the measurement point with the minimum error rate. seek,
initial parameter setting means for supplying the characteristic parameters of the measurement points to the equalizer as initial parameters; and changes in the signal error rate detected by the error rate detection means by changing the characteristic parameters of the equalizer within a predetermined range. characteristic parameter control means for repeatedly performing a control operation to variably control the characteristic parameters of the equalizer in a direction in which the signal error rate decreases based on the degree of the signal error rate; The present invention is characterized in that initial parameters are given and characteristic parameters of the equalizer are variably controlled by the characteristic parameter control means.

The initial parameter setting means may provide the measurement point as an initial parameter to the equalizer when detecting a measurement point whose signal error rate is less than or equal to a predetermined signal error rate. Further, when the signal error rate of the equalizer becomes equal to or higher than a preset signal error rate, the initial parameter setting means resets the initial parameters by setting the characteristic parameter in this state as one of the plurality of measurement points. It can also be configured to perform an action.

F Function In the automatic equalizer according to the present invention, the initial parameter setting means gives initial parameters to the equalizer whose characteristic parameters are freely variable, and the characteristic parameter control means variably controls the characteristic parameters.

The initial parameter setting means sequentially detects the signal error rate of the equalizer and output using the error rate detection means for each measurement point corresponding to a plurality of characteristic parameters set in advance, and determines the measurement point with the minimum error rate. The characteristic parameters of this measurement point are given to the equalizer as initial parameters.

Further, the characteristic parameter control means changes the characteristic parameters of the equalizer within a predetermined range, and based on the degree of change in the signal error rate of the output of the equalizer detected by the error rate detection means, the A control operation is repeatedly performed to variably control the characteristic parameters of the equalizer in a direction that reduces the signal error rate.

G. Embodiment Hereinafter, an embodiment of the automatic equalizer according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a reproduction system of a digital audio chip recorder to which an automatic equalizer according to the present invention is applied.

As shown in Figure 1, this playback system uses a magnetic tape (1).
It is equipped with a magnetic head (2) for reproducing digital audio data recorded on the disc. A reproduction signal reproduced from the magnetic tape (1) by the magnetic head (2) is supplied to an analog-to-digital (A/D) converter (4) via a reproduction amplifier (3). This A/D
A converter (4) binarizes the reproduced signal and converts it into a digital signal. The digital signal obtained by the A/D converter (4) is supplied to the data processing section (6) via the equalizer (5).
) performs predetermined error correction processing, decoding processing, etc. on the digital signal supplied via the equalizer (5). Thereby, the data processing section (6) decodes digital audio data from the digital signal and outputs it as reproduced audio data from the signal output terminal (7).

In this reproduction system, the equalizer (5) constitutes an automatic equalizer (10) according to the present invention, and is configured by three characteristic parameters C+, Cz, and C given by a characteristic parameter setting section (11). : The equalizer characteristics can be changed freely by +.

For example, as shown in FIG. 2, such an equalizer (5) has an input terminal (2) to which the digital signal is supplied.
1) connected in series with the first. Second delay circuit (22)
, (23), and the digital signal is connected to the input terminal (
a first multiplier (24) directly supplied from the input terminal (21);
A second multiplier (
25), and the digital signal is connected to the input terminal (21).
From the above 1. Second delay circuit (22), (23)
a third multiplier (26) supplied through a series circuit, and the first to third multipliers (24) and (25).
, (26) and an adder (27) is used.

In the flower vase (5) having such a configuration, the first multiplier (24) applies the characteristic parameter setting unit (11) to the digital signal directly supplied from the input terminal (21). Characteristic parameter C1 given by
The second multiplier (25
) is connected from the input terminal (21) to the first delay circuit (
The second multiplier (26) weights the digital signal supplied via the input terminal (22) with the characteristic parameter C1 given by the characteristic parameter setting section (11). (21) to the above 1. The digital signal supplied through the series circuit of the second delay circuits (22) and (23) is weighted by the characteristic parameter C1 given by the characteristic parameter setting section (11), and The adder (27) is connected to the first to third multipliers (24).
), (25), and (26), i.e.,
The digital signals weighted by the characteristic parameters C+, Cz, and Cz given by the characteristic parameter setting section (11) are added, and the added output is output as a filtered digital signal to the signal output terminal (28).
).

As shown in FIG. 1, the automatic equalizing vase (lO) according to the present invention is provided with the equalizer whose equalizer characteristics are variable according to three characteristic parameters CI+C2°C3 given by the characteristic parameter setting section (11). A container (5) and
An error rate detection unit (12) detects the signal error rate ER of the output of the equalizer (5), and an error rate detection unit (12) detects the signal error rate ER of the output of the equalizer (5).
), the initial value of the characteristic parameter Ci' + C mushroom + C1, that is, the initial parameter, is set to
), and a characteristic parameter control unit (14) that variably controls the characteristic parameters C1, C2, C1 that the characteristic parameter setting unit (11) gives to the equalizer (5) to optimal values. ).

This automatic equalizer (10) has a characteristic parameter setting section (
11) gives the characteristic parameter C to the equalizer (5),
,C,,C,, the third characteristic parameter C1 is always fixed at a predetermined value, and by variably setting the first and second characteristic parameters C,,C□, the equalizer (
5) provides optimal equalizer characteristics.

The initial parameter setting section (13) includes the equalizer (5).
) first and second characteristic parameters CI+C! As shown in Fig. 3, within a two-dimensional plane where values can be taken, the minimum number of measurement points A, which are considered to be excellent as initial values for each of the above characteristic parameters CI, C, set in advance as shown in FIG. B
, C, D, E, and F, the signal error rate R of the output of the equalizer (5) is sequentially detected by the error rate detection unit (12), and the measurement point with the minimum error rate ER□8 is determined. The characteristic parameters C1 and Cz of the measurement points are set as initial parameters to be applied to the characteristic parameter setting section (11) in accordance with the procedure shown in the flowchart of FIG.

That is, the initial parameter setting unit (13) first sets the measurement points A, B, C, and D in the first step SI when starting the operation of the automatic equalizer (lO).

After setting the variable N that counts E and F to 1, the process moves to the next second step S2.

In this second step S2, a process of determining whether or not the mode is a search mode for setting initial parameters is performed.
If the determination result in this second step S is NO, that is, if the search mode is not set, the process moves to a twelfth step S+Z, which will be described later. If the determination result in the second step SO is YES, that is, the search mode is selected, the process moves to the next third step S.

Here, when the automatic equalizer (10) starts operating, the search mode is set, and the process moves from the second step Sz to the third step.

In this third step S, the error rate detection section (12)
This third step S performs a process of determining whether the signal error rate ER of the output of the equalizer (5) currently detected is larger than a predetermined value of 1.

If the determination result is NO, that is, the signal error rate ER is smaller than the predetermined value of 1, the ninth step S to be described later is performed.
, move on. Further, if the determination result in this fourth step S3 is YES, that is, if the signal error rate ER is greater than the predetermined value, the process moves to the next fourth step S.

In this fourth step S4, the characteristic parameter CI+C of the first measurement point A indicated by the variable N (N=1) is
! is given to the characteristic parameter setting section (11), and the signal error rate ER of the output of the equalizer (5) is detected for the first measurement point A by the error rate detection section (12).

Then, in the next fifth step S, the variable N is incremented, and then the process moves to the next sixth step Sh.

In this sixth step S, the signal error rate ER of the output of the equalizer (5) is measured at all measurement points A, B, and C.

Determination processing is performed to determine whether or not D, E, and F have been detected. If the determination result in the sixth step S6 is NO, the process returns to the second step Sz and repeats the processing operations from the second step S2 to the sixth step 54. As a result, the measurement points A, B, C, D, E
, F, each signal error rate ER is detected in the order of A-+B→C-+D→E→F. Then, the determination result in this sixth step Sh is YES, that is, the signal error rate E for all measurement points A, B, C, D, E, and F.
If R is detected, the process moves to the next seventh step S.

In this seventh step S'l, each measurement point A is measured.

A determination process is performed to determine whether the minimum value ERMIN of the signal error rates ER detected for B, C, D, E, and F is smaller than a predetermined value of 2. This seventh stethop S,
If the determination result is No, that is, the minimum error rate ERNIN smaller than the predetermined value kz cannot be obtained, each of the measurement points A, B, and C is determined by the processing operations from the second step S2 to the sixth step S.

Deciding that the detection of each signal error rate ER for D, E, and F was a mistake, the variable N is set to 1 in the eighth step S, and then the process returns to the second step 52 to detect each signal. The error rate ER detection operation is performed again. Further, if the determination result in the seventh step S is YES, that is, if a minimum error rate ER,4+,4 smaller than the predetermined value is obtained, the process moves to the ninth step S9.

In this ninth step S, a steady mode is set as the operating mode of this automatic flower vase (lO).

In the next 1st step S1°, the characteristic parameters C,,C, An initial parameter whose initial value is the value of is given to the characteristic parameter setting section (11).

In this way, the initial parameter setting section (13) sets the initial parameters to the characteristic parameter setting section (11).
, the control of the characteristic parameter setting section (11)
n is placed under the control of the characteristic variation control section (14).

Furthermore, if the determination result in the third step S3 is No, that is, a measurement point is detected where the signal error rate ER is less than 1 at the predetermined value, the initial parameter setting section (13) 9 step S.

Go to and set steady mode. Then, in the tenth step 311+, the signal error rate ER detected by the determination process in the third step S is set to a predetermined value.
Characteristic parameters of measurement points smaller than C,,C! An initial parameter whose initial value is the value of is given to the characteristic parameter setting section (11). In this way, when a measurement point where the signal error rate ER is smaller than a predetermined value is detected, an initial parameter is set whose initial value is the value of the characteristic parameter C,,C, of the measurement point of that measurement point. As a result, the operation in the search mode described above can be performed quickly.

Furthermore, the characteristic parameter control section (14)
It performs the steady mode control operation of step S, and is configured as shown in FIG. 5, for example.

That is, the characteristic parameter control section (14) controls the equalizer (5) by the characteristic parameter setting section (11).
A control section (31) that sequentially changes the characteristic parameters C+, Cz given to the signal within a predetermined minute range every predetermined short period of time, and the degree of change in the signal error rate ER detected by the error rate detection section (12). A calculation unit (32) that performs the calculation, and the signal error rate ER calculated by the calculation unit (32).
Based on the degree of change in the characteristic parameters C, , , of the equalizer (5), the signal error rate ER decreases.
and a setting section (33) for setting C2.

Then, the control unit (31) selects the values of the characteristic parameters C, , C, given to the equalizer (5) by the characteristic parameter setting unit (11) in the two-dimensional plane shown in FIG. As shown, the above characteristic parameters C,,C.

The value of P + (CI, Cz) → P z (CI + 1
, Ct)→P, (C,+1°Cg+1)→P 4(C+
Control is performed to orthogonally cause minute vibrations in the order of +C*+1).

Further, the calculation unit (32) calculates each value P + (CI
, Ct).

Pz(CI+1.Cz), Pz(CI+1.Cz+1
), P4 (CI.

The above equalizer (5) in the characteristic parameter of ct+1)
Regarding the output, each signal error rate ERI, ERt, ER:+, ER- detected by the error rate detection section (12) is
, the change ΔC in the first characteristic parameter C1-.

Degree of change ΔER in error rate ER with respect to ΔER/ΔC+
is calculated by the first formula, ΔE R (E RI + E Rs) (E Ra +
E R1) ΔC,2...First formula Also, the degree of change ΔER in error rate ER with respect to change ΔC2 in second characteristic parameter C8, ΔER/ΔC! is calculated using the second equation.

ΔER(ERi+ER,)−(ER++ERi)ΔCg
2...The above characteristic parameters C+, C! calculated by the second equation above calculation unit (32). Degree of change ΔER in error rate ER with respect to change ΔCI +ΔCt ΔER/ΔCI +ΔER/
Information on ΔC2 is given to the setting section (33).

The setting section (33) then sets the characteristic parameter C.
Based on the information on the degree of change in error rate ER ΔER/ΔC1, ΔER/ΔC2 with respect to the change in error rate ΔC8ΔC2, new characteristic parameters C,,C, are set as follows so that the above error rate ER becomes smaller. Set to .

That is, the setting unit (33) sets the previous first characteristic parameter C1 as the new first characteristic parameter CI.
Set ΔCI, which is the value of plus the correction value (K・ΔER/ΔC+). Further, the setting section (33) sets a new second
As the characteristic parameter C, ΔC8 is set by adding a correction value (K·ΔER/ΔC2) to the previous value of the second characteristic parameter C2. Here, the above is a proportionality constant.

Note that the process of setting the new characteristic parameter CI+C2 by the setting unit (33) is not limited to linear processing, but may be non-linear processing as long as it can effectively reduce the error rate ER.

The new characteristic parameters C,,C, set by the setting section (33) are given to the control section (31).

Then, the control section (31) repeats the control to cause the new characteristic parameters C+ and Ct to vibrate orthogonally slightly as described above.

In this way, the characteristic parameter control section (14) changes the characteristic parameters C, , C, of the equalizer (5) within a predetermined range, thereby increasing the signal error detected by the error rate detection section (12). Based on the degree of change ΔER in the rate ER, the equalizer (5)
By repeatedly performing a control operation to variably control the characteristic parameters C1, Ct of the equalizer (5), the characteristic parameters C, Ct of the equalizer (5) are brought to a state where the signal error rate ER is minimized.
,C, are automatically controlled.

The characteristic parameter control section (14) sets a characteristic parameter C+ at the fourth measurement point given as an initial parameter by the above-mentioned initial parameter setting section (13),
With Ct as the initial value, the above characteristic parameters C+, C
Perform x control operation.

In this way, the characteristic parameter CI+C! of the fourth measurement point given as an initial parameter by the initial parameter setting section (13) described above! The characteristic parameter control section (14) sets the characteristic parameter C as an initial value.
By performing the control operations for C+ and Cg, the characteristic parameters C+ and Cz can be quickly and reliably converged to the optimum values.

Further, in this embodiment, as shown in FIG. 3, the control operation of the characteristic parameters C, , C, by the characteristic parameter control section (14), that is, the control operation in the steady mode of the eleventh step Sl+, is performed. Each time you do the second
Returning to step St, during the steady motor control operation, steps from the second step Sz to the twelfth step Sl! Moving on to
Signal error rate ER obtained by the error detection section (12)
is a predetermined value k.

A determination process is performed to determine whether or not the value is larger than .

If the determination result in the twelfth step S+t is NO, that is, if the signal error rate ER is smaller than a predetermined value, the process returns to the eleventh step 311 to repeat the steady mode control operation.

In addition, the above twelfth step S1. The judgment result is Y
If ES, that is, the signal error rate ER is greater than a predetermined value, the process moves to the next 13th step knob srs.

In this 13th step S11, a determination process is performed as to whether or not the number of times n in which the signal error rate ER continues to be greater than a predetermined value is greater than 4 to a predetermined value. If the determination result in step S11 is NO, the process returns to the eleventh step S11 to repeat the steady mode control operation.

Also, the determination result in this 13th step S13 is Y.
If ES, that is, the above-mentioned signal error rate ER is greater than 3 at a predetermined value for a predetermined number of times in a row, the next first
Proceeding to step 514, the measurement point P indicated by each characteristic parameter C+ and Ct at that time is set as an even-numbered measurement point, and a search mode is set.

Then, in the next fifteenth step SI5, the variable N is set to 1, and then the fourth step S! Go back to the search mode described above.

In the normal operation mode, the signal error rate ER is greater than a predetermined value k a predetermined number of times.

If a continuous state occurs and the mode is shifted to the search mode, the processing operations from the second step S2 to the sixth step S are repeated to find the measurement points A and B set in advance.
, C, D, E, F and the measurement point P0 set in the fourteenth step S14, A-+P0→B-+P0→
The above-mentioned search operation is performed by sequentially detecting each signal error rate ER in the order of C→P0→D→P0→E−+p,→F.

Then, new initial parameters based on the search operation are set in the tenth step 5l11, and the process returns to the eleventh step S11 to restart the steady mode control operation.

In the above search operation, the signal error rate "ER" of the measuring point P0 is the same as that of the measuring points A, B, C, D, and E.

If it is the same as the minimum error rate ER□8 of F, the characteristic parameters C, , C, of the measurement point P0 are preferentially set as the initial parameters. In addition, the second step S2. 7th step S? and 12th step SI□
+, kg, k for each judgment value of the signal error rate ER in
i is k + < k z < k s or kl < k3 < k z
The relationship is set as follows.

H Effects of the Invention As described above, in the automatic equalizer according to the present invention, for an equalizer whose characteristic parameters are variable, each characteristic parameter corresponding to a plurality of preset characteristic parameters is set by the initial parameter setting means. Since the characteristic parameters of the measurement point with the smallest signal error rate among the measurement points are given as initial parameters, the characteristic parameter control means performs a control operation to converge the characteristic parameters of the equalizer to the optimum values. You can start from somewhere nearby. Furthermore, since the initial parameter setting means detects the signal error rate of the output of the equalizer for each measurement point corresponding to a plurality of characteristic parameters, the characteristic parameter control means can efficiently adjust the characteristic parameters. In addition, initial parameters that can be reliably converged to optimal values can be set.

Thereby, the characteristic parameter control means can efficiently and reliably converge the characteristic parameters to the optimum values. Moreover, when the initial parameter setting means detects a measurement point whose signal error rate is less than or equal to a preset signal error rate,
By supplying the measurement point to the equalizer as an initial parameter, the initial parameter setting operation can be performed quickly. Furthermore, when the signal error rate of the equalizer becomes equal to or higher than a preset signal error rate during the characteristic parameter control operation by the characteristic parameter control means, the initial parameter setting means adjusts the characteristic parameters in this state to the plurality of characteristic parameters. By performing the initial parameter setting operation as one of the measurement points, the initial parameter resetting operation can be performed quickly and reliably.

Therefore, according to the present invention, it is possible to provide an automatic equalizer that can efficiently and reliably converge the characteristic parameters of the equalizer to the optimum values and provide the optimum equalizer characteristics to the input signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an automatic equalizer in which the present invention is applied to a digital audio tape recorder, and FIG. 2 is a block diagram showing a specific example of the configuration of the equalizer constituting the automatic equalizer. 3 is a two-dimensional coordinate plan view of the characteristic parameters supplied to explain the operation of the initial parameter setting section that constitutes the automatic equalizer, and FIG. 4 is used to explain the operation of the automatic equalizer. Flowchart, FIG. 5 is a block diagram showing an example of the functional configuration of the characteristic parameter control section constituting the automatic equalizer, and FIG. 6 is a characteristic diagram for explaining the control operation by the characteristic parameter control section. FIG. 2 is a two-dimensional coordinate plan view of parameters. FIG. 7 is a two-dimensional coordinate plan view of characteristic parameters for explaining the problems of the automatic equalizer. 5 ・・・・・・・・・ 10 ・・・・・・・・・ 11 ・・・・・・・・・ 12 ・・・・・・ 13 ・・・・・・・・・ 14 ・・・・・・ etc.Vase Automatic equalizer characteristic parameter setting section Error rate detection section Initial parameter setting section Characteristic parameter control section

Claims (3)

[Claims] (1) An equalizer with variable characteristic parameters, an error rate detection means for detecting the signal error rate of the output of the equalizer, and the above-mentioned for each measurement point corresponding to a plurality of preset characteristic parameters. initial parameter setting means for sequentially detecting the signal error rate of the output of the equalizer by error rate detection means, determining a measurement point with a minimum error rate, and providing the characteristic parameter of this measurement point to the equalizer as an initial parameter; , the characteristic parameters of the equalizer are varied within a predetermined range, and the characteristics of the equalizer are adjusted in a direction in which the signal error rate decreases based on the degree of change in the signal error rate detected by the error rate detection means. characteristic parameter control means for repeatedly performing a control operation for variably controlling parameters; the initial parameter setting means gives initial parameters to the equalizer, and the characteristic parameter control means varies the characteristic parameters of the equalizer; An automatic equalizer characterized by controlling. (2) When the initial parameter setting means detects a measurement point having a signal error rate equal to or less than a preset signal error rate, the initial parameter setting means supplies the measurement point to the equalizer as an initial parameter. Automatic equalizer as described. (3) When the signal error rate of the equalizer becomes equal to or higher than a preset signal error rate, the initial parameter setting means sets the characteristic parameter in this state to one of the plurality of measurement points.
2. The automatic equalizer according to claim 1, further comprising an initial parameter setting operation.