JPS61196613A - Automatic equalizer control system - Google Patents

Abstract

PURPOSE:To realize an automatic equalizer in which a characteristic change is very little and stability is excellent at the time of the completion of the training and at the time of communication by detecting, by an estimation value detecting circuit from the above-mentioned equalizer circuit output, the estimation value to estimate whether or not the equalizer circuit output is a signal which can identify the correct data and comparing with the reference value. CONSTITUTION:An estimation value to estimate the equalizing condition from an output signal is detected by an estimation value detecting circuit, the output of the said detecting circuit 4 and a reference value (1) of a reference value generating device 12 are compared by a comparing circuit 13, and a reference value (2) of a reference value generating device 14 is compared by a comparing circuit 15. When the estimation value of the estimation value detecting circuit 4 is smaller than the reference value (1), an equalizing characteristic is changed to the direction to increase the estimation value, when the above-mentioned estimation value is larger than the reference value (2), the equalizing characteristic is changed to the direction to decrease the estimation value, and when the estimation value is larger than the reference value (1) and smaller than the reference value (2), the equalizing characteristic is not changed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is an automatic system that automatically adapts to the situation and suppresses code amount interference due to the characteristics of the transmission path in digital transmission, so that correct data can be received. Concerning the control method of the converter.

(Prior Art) FIG. 2 is a block diagram showing an example of the configuration of a conventional automatic equalizer of this type. The received signal at the input terminal 1 passes through the equalization circuit 2 and is outputted to the output terminal 3 as a signal in which code amount interference is suppressed and data can be correctly identified. At this time, it is necessary to set the characteristics of the equalization circuit 2 so as to best suppress code amount interference by adapting to the conditions of the transmission path. This is usually the result of detecting an evaluation value for evaluating the equalization status from the output signal by an evaluation value detection circuit 4, and comparing the evaluation value with a predetermined reference value of a reference value generator 6 by a comparison circuit 5. The setting is made by the control circuit 7 based on the following. As a specific example, a decision feedback equalizer as shown in Convergence of Decision Feedback Equalizer (IEICE technical research report CS 82-85, 1982) is used in the equalization circuit 2. I will explain the case where

FIG. 3 is a block diagram showing an example of the configuration of a decision feedback equalizer. The signal whose data is identified by the identification circuit 8 from the equalization circuit output signal is passed through a delay circuit 9 having a delay amount corresponding to the data identification cycle of each stage, and then sent to a multiplication circuit 10 by weights Wl to Wk for each output of each stage. By multiplying the output signals of each multiplication circuit 10 and adding them to the input signal of the equalization circuit 2 by the addition circuit 11, code amount interference is suppressed. At this time, the weights W□ to Wk are controlled to adapt to the conditions of the transmission path so as to suppress the code amount interference from the first to the second identification time after the interfering pulse. That is, each weight W1 to Wk
Is isolation 1 prior to normal communication? However, the equalization circuit output signal value at the first identification point after the peak position of the received pulse is hi, and the polarity of the received pulse is S (+1 or -1).Wl−Δ・sgn ( h i )・S−+W,
It is updated using algorithm (1). However, in equation (1), 1≦i≦, sgn(x) represents the polarity of be. In the decision feedback equalizer shown in FIG. 3, the amount of code amount interference at each identification point corresponds to the evaluation value in FIG. 2, the reference value is zero, and each weight W1 to Wk determines the equalization characteristics. It is a nogura meter.

The training is completed by repeating the evaluation values as shown in Figure 4, or by using the automatic equalization completion determination method (Special Publication No.
97927) by repeating each weight W0 to Wk. Further, communication control after training is performed by detecting a data pattern that can be considered as an isolated pulse, and using the same algorithm as during training.

(Problem to be Solved by the Invention) However, in the above-mentioned method, the equalization characteristics are constantly changing at the end of training or when isolation/glue is detected during communication, so the equalization output is not stable and the This method has the drawback of increasing noise in terms of measurements.

The present invention solves the above-mentioned problems by performing control in an automatic equalizer so that the evaluation value falls within a predetermined reference range, thereby realizing an automatic equalizer with excellent stability.

(Means for Solving the Problems) The present invention provides an evaluation value detection circuit for detecting an evaluation value for evaluating an equalization situation in a control method for an automatic equalizer, and an evaluation value detection circuit for detecting an evaluation value in order to evaluate an equalization situation, and an evaluation value of the detection circuit that is determined in advance. An upper limit value comparison circuit and a lower limit value comparison circuit that compare whether the value is within the reference range set, or whether it is below the lower limit of the reference range, or whether it is greater than the upper limit of the reference range, and the results of the respective comparison circuits. This is an automatic equalizer control method that includes a control circuit that changes the evaluation value based on the equalization characteristics.

(Function) An evaluation value for evaluating whether the output of the equalization circuit is a signal that can identify correct data is detected by the evaluation value detection circuit from the output of the equalization circuit, and is compared to a reference value. Send to circuit. Comparison of evaluation values is performed by an upper limit value comparison circuit and a lower limit value comparison circuit. That is, the upper limit comparison circuit detects whether or not the upper limit of the reference value is greater than the upper limit, and the lower limit value comparison circuit detects whether or not it is smaller than the lower limit of the reference value. Each of the comparison circuit outputs is sent to a control circuit.

The control circuit controls the equalization characteristic so that the evaluation value falls within the reference range based on the comparison circuit output of the upper limit value and the comparison circuit output of the lower limit value.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention. The received signal from the input terminal 1 passes through the equalization circuit 2 and is outputted to the output terminal 3 as a signal in which intersymbol interference is suppressed and data can be correctly identified. At this time, an evaluation value for evaluating the equalization status is detected from the output signal by the evaluation value detection circuit 4, and the output of the detection circuit 4 and the reference value generator 1
A comparison circuit 13 compares the reference level (1) of the reference value generator 14, and a comparison circuit 15 compares the reference level (2) of the reference value generator 14 with the reference level (1) of the reference value generator 14. The reference value (1) and reference value (2) represent the upper and lower limits of the reference range. Now the reference value (1) is the lower limit, the reference value (
2) is the upper limit, the output of the comparison circuit 13 indicates whether the evaluation value is above or below the lower limit, and the output of the comparison circuit 15 indicates whether the evaluation value is above or below the upper limit. The evaluation value is the standard value (1
) and smaller than the reference value (2), it is within the reference range. The control circuit 16 controls the equalization characteristics based on the outputs of the comparison circuits 13 and 15 so that the evaluation value falls within the reference range. That is, if the evaluation value of the evaluation value detection circuit 4 is smaller than the reference value (1), the equalization characteristic is changed in the direction of increasing the evaluation value, and if the evaluation value is larger than the reference value (2), the equalization characteristic is changed in the direction of lowering the evaluation value. The equalization characteristic is changed, and if the evaluation value is larger than the reference value (1) and smaller than the reference value (2), control is performed such that the equalization characteristic is not changed.

According to the configuration shown in Figure 1, the reference range width, that is, the reference value (2)
The difference between the reference value (1) and the reference value (1) is small enough to obtain sufficient equalization accuracy and large enough to be sufficiently compared by the comparison circuits 13 and 15, that is, larger than the dead width of the comparison circuits 13 and 15. As shown in the example of updating the equalization characteristic in FIG. 5, when the training is completed, the equalization characteristic does not fluctuate.

The end of training is determined by stopping the change in the evaluation value, or by stopping the change in the weights Wl to Wk in FIG.

Further, during communication, the equalization characteristics do not change until the characteristics of the transmission path change.

As described above, according to the method of the present invention, it is possible to realize a stable automatic equalizer with little variation in equalization characteristics.

Note that when there is external noise, if the reference range width is small, fluctuations in the evaluation value due to the noise will lead to fluctuations in the equalization characteristics, but equalization can be achieved by increasing the reference range width within a range that does not significantly degrade the equalization characteristics. Fluctuations in characteristics can be kept to a minimum.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to realize an automatic equalizer with excellent stability, which exhibits extremely little variation in characteristics at the end of training and during communication, and can be applied to various transmission devices.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an automatic equalizer according to the present invention, FIG. 2 is a block diagram showing a conventional automatic equalizer, FIG. 3 is a block diagram showing an example of the configuration of an equalization circuit, and FIG. 5 is an explanatory diagram showing the control situation of a conventional automatic equalizer, and FIG. 5 is an explanatory diagram showing the control situation of the automatic equalizer according to the present invention. DESCRIPTION OF SYMBOLS 1... Input terminal, 2... Equalization circuit, 3... Output terminal, 4... Evaluation value detection circuit, 5... Comparison circuit, 6...
... Reference value generator, 7... Control circuit, 8... Identification circuit, 9... Delay circuit, 10... Multiplication circuit, 11...
- Addition circuit, 12... Reference value generator, 13... Comparison circuit, 14... Reference value generator, 15... Comparison circuit,
16...Control circuit. Patent applicant Oki Electric Industry Co., Ltd. Figure 4 Figure 5

Claims (1)

[Claims] A control method for an automatic equalizer that changes equalization characteristics in accordance with transmission path conditions, comprising an evaluation value detection means for evaluating an equalization situation, and an evaluation value of the detection means. a comparison means for determining whether or not it falls within a predetermined reference range; and a comparison means for determining whether or not the evaluation value falls within a predetermined reference range; 1. An automatic equalizer control method, comprising a control means for controlling the equalization characteristic so that the equalization characteristic falls within a reference range.