JP2006109207A - Receiving circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein characteristics of an adaptive filter takes a longer time for converging on an optimum solution or they converges on a local solution, which is not an optimum solution, when waveform equalization is adaptively applied to a signal received through a system with unknown transfer characteristics, if the quality of an ideal signal decoded from the received signal is poor. <P>SOLUTION: At a pre-stage of an adaptive waveform equalization circuit 1, the quality of a received signal is inspected and the attenuation amount of the signal is calculated by a signal inspection means 13. Based on the result, predetermined frequency bands and an amplification rate for these frequency bands are determined by a boost setting means 12. According to the result determined by the boost setting means 12, a specific frequency band of the received signal is emphasized with a specific amplification rate by a waveform shaping means 11. Thereby, the convergence characteristics of a filter 14 at a post-stage adaptive waveform equalization circuit 1 is improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a receiving circuit including an adaptive waveform equalization circuit that can be used for communication or a read channel of an optical disk or a magnetic disk.

  The waveform equalization circuit is a circuit that shapes a signal received from a transmission line such as a communication cable or a signal received from an optical disk, a magnetic disk, or the like via a read head into an appropriate state. For example, in communication, signal transmission characteristics differ depending on conditions such as cable length and environmental temperature. Further, in the case of an optical disk or a magnetic disk, the signal quality varies greatly depending on the tilt of the disk with respect to the read head, the dirt on the disk, and the like. In order to shape a waveform distorted under such various conditions into an ideal state, a waveform equalization circuit is required.

  The waveform equalization circuit is basically composed of a filter having a reverse characteristic of the transfer characteristic of the system that has passed through until the signal is received. This filter is usually composed of a plurality of delay elements connected in series, a plurality of taps each provided with a multiplier that multiplies the output of these delay elements by a tap coefficient, and an adder that adds the outputs of the respective taps. Transversal filter. The characteristics of the filter are determined by the tap coefficient.

  Among such waveform equalization circuits, there is an adaptive waveform equalization circuit that adaptively changes the filter characteristics with respect to fluctuations in the transfer characteristics of the system accompanying changes in various conditions. Adaptive waveform equalization circuits can be flexibly adapted to changes in cable length and the like, and thus are widely used in communication devices and the like. In the adaptive waveform equalization circuit, tap coefficients are sequentially updated according to the difference between the filter output and the ideal signal, and the filter characteristics are adjusted so that the filter output approaches the ideal signal. As a tap coefficient update algorithm, a least mean square (LMS) algorithm, a sequential least square (RLS) algorithm, or the like is known.

  In the case of a communication device such as a gigabit LAN, since the receiving node does not know the data transmitted by the transmitting node and the transmission characteristics of the cable connecting the nodes, it is unknown what signal waveform the ideal signal has. For this reason, it is necessary to generate an ideal signal necessary for matching the filter characteristics from the received signal. Usually, the ideal signal is generated by a decoder. The decoder refers to the output signal of the filter, compares the amplitude level with an arbitrary threshold value, and determines the decoding result. Such a decoder is called a slicer and has a simple structure and operates at high speed. However, since the decoding result is determined only based on a specific threshold, the reliability of the decoding result is low depending on the quality of the input signal. There is. Apart from this, when the received signal is decoded according to a known rule, a Viterbi decoder or the like can be used as a decoder.

  In the initial stage of adjusting the filter characteristics of the adaptive waveform equalizer, the output signal of the filter is often far from the transmitted signal. Also, since the ideal signal generated by the decoder is also based on the output signal of the filter, the ideal signal itself may be completely different from the actually transmitted signal. In such a situation, it takes a very long time for the filter characteristics to converge to the optimal solution, and in the worst case, the ideal signal with low reliability is referred to, so that it converges to the local solution instead of the optimal solution.

For such problems, tap coefficients when the filter characteristics are optimal under the assumed use conditions are obtained in advance, and selected according to the environment in which they are used, and the initial value of the tap coefficient The method of giving as is proposed. Specifically, when reading the magnetic tape, the initial tap coefficient values of different types of tapes are held in advance, and the appropriate tap coefficient initial value is selected by a selection signal, so that the tape type may change. Filter characteristics converge quickly and accurately. The filter output can output a high-quality output signal from the beginning of operation, although it contains equalization errors caused by temperature changes, etc., and the ideal signal generated by the decoder also has reliable quality. As a result, the convergence time of the filter characteristics is shortened, and the possibility of falling into a local solution is also reduced (see Patent Document 1).
Japanese Patent Laid-Open No. 5-40907

  As described above, as one of the methods for efficiently converging the filter characteristics of the adaptive waveform equalization circuit to the optimum value, a method using a preliminarily prepared initial value of the filter tap coefficient has been proposed. If the quality of the signal input to the filter is worse than expected, the quality of the filter output may be degraded and the ideal signal may be deteriorated. As a result, the filter characteristics may not converge to the optimal solution.

  Taking a gigabit LAN as an example, the cable length may be any length as long as it is 100 m or less, and there are a plurality of types of cables. Also, the performance on the transmission side is not uniquely determined. For this reason, it is difficult to predict the transfer characteristics of the entire system, and it is not effective to prepare an initial value of the tap coefficient.

  An object of the present invention is to improve the quality of a signal input to an adaptive waveform equalization circuit while suppressing an increase in excessive noise, so that the adaptive waveform equalization circuit can converge to an optimum solution of filter characteristics. To make it easier.

  In the receiving circuit according to the present invention, in the preceding stage of the adaptive waveform equalization circuit, the quality of the received signal is inspected by the signal inspecting means and the attenuation of the signal is calculated. The amplification factors for these frequency bands are obtained, and the waveform shaping means emphasizes a specific frequency band of the received signal with a specific amplification factor in accordance with the result obtained by the boost setting means.

  Another receiving circuit according to the present invention calculates the attenuation amount of the signal obtained by the gain adjusting means referring to the filter output in the previous stage of the adaptive waveform equalizing circuit, and based on the result, the boost setting means determines a predetermined amount. The frequency enhancement means calculates the frequency bands and the amplification factors for those frequency bands, and the waveform enhancement means emphasizes a specific frequency band of the received signal with a specific amplification factor according to the result obtained by the boost setting means. .

  The signal inspection means according to the present invention comprises amplitude level detection means for observing the amplitude of the received signal and outputting the difference from the ideal amplitude level as an attenuation level signal.

  In another configuration, the signal inspection means according to the present invention comprises attenuation amount determination means for measuring the frequency component of the received signal and outputting the ratio between the spectral intensity in the low frequency region and the spectral intensity in the high frequency region as an attenuation level signal.

  In these configurations, the boost setting means includes a reference memory that holds a boost control signal indicating a combination of n boosting bands (n is an integer of 2 or more) and an amplification factor according to the attenuation amount, and the attenuation level. A unique boost control signal is output according to the signal.

  In still another configuration, the signal inspection means according to the present invention holds the information of the frequency spectrum of the ideal signal in the ideal signal memory, detects the frequency component of the received signal, compares it with the result of normalization, and compares the difference between the two. The boost setting means outputs a filter setting for reducing the difference between the two as a boost control signal.

  The waveform shaping means and the waveform emphasis means according to the present invention amplify a specific frequency band with a specific amplification factor according to the boost control signal.

  The boost setting means according to the present invention is controlled to operate only for a specific period of the training period for establishing a communication connection, for example, and thereafter to stop the operation and fix the boost control signal.

  By taking such measures, the receiving circuit according to the present invention can improve the quality of the signal input to the adaptive waveform equalization circuit while suppressing an increase in excessive noise, and adaptive waveform equalization. It is possible to facilitate the convergence of the filter characteristic to the optimum solution in the circuit.

  Hereinafter, a waveform equalization circuit used in data communication between devices connected by a cable having an arbitrary length will be described as an example.

  FIG. 1 is a block diagram showing a first embodiment of the present invention. In FIG. 1, 11 is a waveform shaping means, 12 is a boost setting means, 13 is a signal inspection means, 14 is a filter, 15 is a decoding means, 16 is a computing unit, 17 is an adaptive control means, and 1 is an adaptive waveform equalization circuit. Indicates.

  In this embodiment, the signal inspection means 13 inspects the state of the received signal, and the boost setting means 12 outputs a boost control signal that determines the characteristics of the waveform shaping means 11 according to the inspection result. The waveform shaping means 11 receives the boost control signal, enhances the received signal accordingly, and amplifies the received signal according to the output of the filter 14. The enhancement of the received signal here means that a specific frequency component included in the signal is amplified. The adaptive waveform equalization circuit 1 receives the signal shaped by the waveform shaping means 11, decodes the waveform equalized by the filter 14 by the decoding means 15, and uses the result decoded by the decoding means 15 as an equalized output. Output. At this time, the characteristic of the filter 14 is updated by the adaptive control means 17 while taking into account the difference between the input and output of the decoding means 15. As described above, the receiving circuit according to the present invention is configured to shape the signal input to the adaptive waveform equalization circuit 1 according to its quality.

  FIG. 2 shows an example in which the waveform shaping means 11 in FIG. 1 is configured with a transversal filter. The simplest structure of the waveform shaping means 11 is based on a transversal filter as shown in FIG. In FIG. 2, 30 is a delay element, 31 is a multiplier, 32a is an adder, and 32b is an amplifier. The multiplier 31 constitutes a tap that determines the characteristics of the waveform shaping means 11 by the boost control signal. In other words, the boost setting means 12 outputs the tap coefficient of the transversal filter as the boost control signal, so that it is possible to enhance an arbitrary frequency spectrum of the received signal. On the other hand, the amplification factor of the amplifier 32b is adjusted so that the output of the filter 14 has a predetermined amplitude.

  FIG. 3 shows the signal inspection unit 13 and the boost setting unit 12 in a configuration in which the signal inspection unit 13 inspects the signal quality by paying attention to the amplitude level of the received signal. In FIG. 3, 33 is an amplitude level detecting means, 34 is a slicer, and 35 is a reference memory.

  The amplitude level detection means 33 observes the received signal for a certain period and records the amplitude level of the signal. After a certain period, the maximum amplitude is extracted from the recorded amplitude levels and compared with the ideal amplitude level. The ideal amplitude level is a value that the received signal takes when the adaptive waveform equalization circuit 1 communicates through a cable having a length that can sufficiently equalize the waveform even when the received signal is not emphasized. The maximum amplitude level that can be obtained. Note that the average amplitude level may be referred to instead of the maximum amplitude level of the received signal. In that case, the average amplitude level is also used as the ideal amplitude level. Since the amplitude level of the received signal is attenuated according to the distance of the cable, it is possible to estimate how long the currently received signal is sent through the cable by comparing with the ideal amplitude level. . The amplitude level detection means 33 outputs this estimation result.

  The reference memory 35 stores information indicating the frequency band to be amplified and the amplification factor, for example, in cables of 50 m, 100 m, 150 m, and 200 m. Such information can be easily obtained by measuring the frequency response characteristics of the cable.

  The slicer 34 discretizes the estimated cable length output by the amplitude level detection means 33 so as to match the cable length for which the reference memory 35 holds information according to a specific threshold value. For example, when the reference memory 35 has cable information of 50 m and 100 m, when the amplitude level detection means 33 outputs an estimated value indicating 60 m, it is converted to 50 m, and when an estimated value indicating 80 m is output. Converts to 100m. The reference memory 35 outputs information corresponding to the output of the slicer 34 as a boost control signal.

  FIG. 4 shows the signal inspection means 13 and the boost setting means 12 in another configuration in which the signal inspection means 13 inspects the signal quality by paying attention to the amplitude level of the received signal. In FIG. 4, reference numeral 41 denotes interpolation means. In this configuration, the reference memory 35 outputs a candidate boost control signal based on the estimation result output from the amplitude level detection means 33, and the interpolation means 41 interpolates and outputs the boost control signal according to the estimation result. For example, when the reference memory 35 holds a boost control signal for cables of 100 m, 200 m, and 300 m, and the amplitude level detection means 33 outputs an estimation result indicating 140 m, the reference memory 35 stores the cables of 100 m and 200 m. The boost control signal is output as a candidate, and the interpolation means 41 generates and outputs a boost control signal suitable for 140 m by a specific calculation. As the specific calculation performed by the interpolation means 41, linear interpolation can be most easily realized, but another interpolation method may be used according to the cable characteristics.

  FIG. 5 shows the signal inspection unit 13 and the boost setting unit 12 in a configuration in which the signal inspection unit 13 inspects the signal quality by paying attention to the frequency component of the received signal. In FIG. 5, reference numeral 51 denotes attenuation amount determining means.

  FIG. 6 shows two examples of frequency components of the received signal, that is, a 10 m cable and a 100 m cable. The horizontal axis is the frequency, and the vertical axis is the spectrum intensity of the received signal. As shown in FIG. 6, the frequency spectrum of the received signal tends to decrease particularly in the high frequency region as the cable length increases.

  The attenuation amount determination means 51 shown in FIG. 5 estimates how long the current received signal is sent through the cable based on the frequency characteristics of such a cable. The cable length can be estimated by taking the ratio of the spectral intensity in the low frequency region and the high frequency region and comparing it with the ideal frequency ratio. The change in the spectral intensity due to the cable length is remarkable in the high frequency region, but by taking the ratio with the low frequency region, the difference in signal amplitude can be normalized and the comparison becomes easy. Here, the ideal frequency ratio is a received signal when the adaptive waveform equalization circuit 1 communicates through a cable having a length that can sufficiently equalize the waveform even when the received signal is input without emphasizing the received signal. Is the ratio of the low frequency component and the high frequency component of the frequency spectrum that can be taken.

  Further, as another estimation method, a method may be used in which the frequency characteristic is extracted after the received signal is amplified to the ideal amplitude value by the attenuation amount determination means 51, and the difference from the ideal spectrum intensity in the high frequency region is used as the estimation result. . Here, the ideal amplitude value is the amplitude value of the received signal when communication is performed with the cable length when the ideal spectrum intensity is obtained.

  By such a method, the estimated value of the cable length output from the attenuation amount determining means 51 is converted by the slicer 34 so as to match the discrete cable length for which the reference memory 35 holds information. The reference memory 35 outputs information corresponding to the output of the slicer 34 as a boost control signal.

  FIG. 7 shows the signal inspection unit 13 and boost setting unit 12 in another configuration in which the signal inspection unit 13 inspects the signal quality by paying attention to the frequency component of the received signal. This configuration is similar to the configuration in which the quality of the signal is checked by paying attention to the amplitude level of the received signal shown in FIG. 4, and the attenuation amount determination means 51 based on discrete information held in the reference memory 35. The interpolation means 41 generates a boost control signal suitable for the estimation result output from the. The generation of the boost control signal performed by the interpolation means 41 can be realized most easily by linear interpolation as in the configuration shown in FIG. 4, but another interpolation method may be used according to the cable characteristics.

  FIG. 8 shows the signal inspection means 13 and the boost setting means 12 in still another configuration in which the signal inspection means 13 pays attention to the frequency component of the received signal and inspects the signal quality. In FIG. 8, 73 is a signal characteristic detecting means, 74 is a comparing means, 75 is an ideal signal memory, and 76 is a boost control signal generating means.

  The signal characteristic detecting means 73 receives the received signal for a certain period and detects the spectrum intensity of each frequency. This detection can be easily realized by using generally known Fourier transform. This detection result is compared with the contents of the ideal signal memory 75 by the comparison means 74. Here, the ideal signal memory 75 stores the spectral intensity of each frequency in the ideal state. The ideal state means a state in which the adaptive waveform equalization circuit 1 is communicating with a cable length that can sufficiently equalize the waveform even if the received signal is input without emphasizing.

  In the comparison by the comparison means 74, since the spectral intensity of the signal is affected by the signal attenuation rate, the amplitude levels of the actual received signal and the received signal in the ideal state must be equal. For this reason, the ideal signal memory 75 holds the amplitude level of the signal in the ideal state, and in response to this, the signal characteristic detection means 73 normalizes the output spectral intensity detection result. In this normalization, the amplitude level of the received signal is detected, the attenuation rate is calculated by comparison with the amplitude level in the ideal state indicated by the ideal signal memory 75, and the received signal amplified based on this is Fourier transformed. It is done by doing. Of course, without referring to the amplitude level, the ratio of the spectral intensity in the low frequency region between the received signal and the ideal state signal held in the ideal signal memory 75 is used as the attenuation rate, and each frequency obtained as a result of the Fourier transform of the received signal. May be amplified based on the obtained attenuation rate. In this case, the ideal signal memory 75 does not need to hold the amplitude level in the ideal state, and the signal characteristic detection unit 73 does not need to detect the amplitude level of the received signal.

  The output of the comparison means 74 indicates the difference in each frequency component of the received signal with respect to the ideal state. Based on this difference, the boost control signal generation means 76 determines the characteristics of the waveform shaping means 11. As a method for determining the characteristics, there is a method of setting the filter stop band and the pass band based on the magnitude of the difference in the spectrum intensity in each frequency component. That is, when the difference in spectrum intensity is smaller than a certain threshold, the frequency band is set as a stop band, and when it is larger, the pass band is set and the amplification factor is set according to the magnitude of the difference. The boost control signal generation unit 76 outputs the tap coefficient that realizes the filter characteristic set in this way to the waveform shaping unit 11 as a boost control signal. In this case, the waveform shaping means 11 outputs the frequency band set as the stop band by the boost control signal as it is in addition to the structure for adding the output of the transversal filter to the received signal as shown in FIG. The filter may be configured to amplify and output the set frequency band with the amplification factor set by the boost control signal.

  In the first embodiment described so far, the signal inspecting unit 13 receives the received signal, but feedback control with reference to the output of the waveform shaping unit 11 may be performed.

  FIG. 9 is a block diagram showing a second embodiment of the present invention. In FIG. 9, 21 is a waveform emphasizing means, 22 is a boost setting means, and 23 is a gain adjusting means. The gain adjusting means 23 changes the amplitude level of the input signal of the adaptive waveform equalization circuit 1 based on the amplitude of the output signal of the filter 14. That is, the block comprising the waveform emphasizing means 21 and the gain adjusting means 23 in FIG. 9 has the same circuit configuration as the waveform shaping means 11 shown in FIG. Normally, the longer the cable used for communication, the more the amplitude level of the received signal is attenuated. Therefore, the gain adjusting means 23 amplifies the input signal in order to make the output signal of the filter 14 an ideal amplitude level. This amplification factor is obtained immediately after the start of communication. The boost setting means 22 refers to this amplification factor and controls the characteristics of the waveform enhancement means 21.

  The boost setting means 22 of the second embodiment performs the same operation with the same configuration as the boost setting means 12 of the first embodiment described above. That is, the boost setting unit 22 includes the reference memory 35 shown in FIG. 3 or 5 when the gain adjusting unit 23 outputs a discrete gain corresponding to the information held in the reference memory 35. In this case, the reference memory 35 holds a boost control signal for a specific amplification factor, and selects and outputs the boost control signal to the waveform emphasizing means 21 in accordance with the input amplification factor.

  Further, the boost setting means 22 has a structure including the interpolation means 41 and the reference memory 35 shown in FIG. 4 or 7 when the gain adjustment means 23 does not discretize the output amplification factor. . In this case, the boost setting means 22 receives the attenuation rate, and the reference memory 35 selects and outputs a boost control signal that seems to be most appropriate for the received attenuation rate. The interpolation unit 41 performs an interpolation process based on the boost control signal and the attenuation rate output from the reference memory 35, and outputs the result to the waveform enhancement unit 21 as a final boost control signal. As for the interpolation processing performed here, linear interpolation can be most easily realized as in the configuration shown in the first embodiment, but another interpolation method may be used according to the cable characteristics.

  In the configuration described so far, the boost setting means 12 and 22 operate only during a specific period of communication, and stop operating during other periods. In the first embodiment, the waveform shaping means 11 is used in the second implementation. In a form, you may fix the waveform emphasis means 21 to the characteristic prescribed | regulated by the boost control signal produced | generated in the period. In general, a receiving circuit including an adaptive waveform equalization circuit requires a period called a training period. The boost setting means 12 and 22 are operated only for a certain period within this period, and thereafter the operation is stopped. .

  The training period is a period in which signals according to a known rule are exchanged on both the transmission side and the reception side to bring the characteristics of the filter 14 close to an ideal state. The fact that the signal received during the training period is a known signal means that the ideal amplitude level in the amplitude level detecting means 33, the ideal frequency ratio in the attenuation amount judging means 51, and further the ideal spectrum held in the ideal signal memory 75. It means that it can be obtained uniquely. For this reason, more accurate operation is possible than operating the boost setting means 12 and 22 for signals in the normal communication period that change randomly. Further, while the boost setting means 12 and 22 are stopped, the effect of reducing power consumption can be obtained by simultaneously stopping the signal inspection means 13 and the gain adjusting means 23.

  The receiving circuit according to the present invention has a feature that the efficiency of waveform equalization in the adaptive waveform equalization circuit is improved by adaptively correcting the signal in advance in accordance with the quality of the received signal. It is useful as an application technique for waveform equalization and waveform equalization in the read channel system of optical disks and magnetic disks.

It is a block diagram which shows the 1st structural example of the receiving circuit by this invention. It is a block diagram which shows the example which comprised the waveform shaping means in FIG. 1 with the transversal filter. It is a block diagram which shows the example of the signal test | inspection means and boost setting means in FIG. 1 when paying attention to the amplitude level of a signal. It is a block diagram which shows another example of the signal test | inspection means and boost setting means in FIG. 1 when paying attention to the amplitude level of a signal. It is a block diagram which shows the example of the signal test | inspection means and boost setting means in FIG. 1 when paying attention to the ratio of the frequency component of a signal. It is a figure which shows the difference in the frequency characteristic of the received signal in case cable length differs. It is a block diagram which shows another example of the signal test | inspection means in FIG. 1 at the time of paying attention to the ratio of the frequency component of a signal, and a boost setting means. It is a block diagram which shows another example of the signal test | inspection means in FIG. 1 at the time of paying attention to the frequency spectrum of a signal, and a boost setting means. It is a block diagram which shows the 2nd structural example of the receiving circuit by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Adaptive waveform equalization circuit 11 Waveform shaping means 12 Boost setting means 13 Signal inspection means 14 Filter 15 Decoding means 16 Calculator 17 Adaptive control means 21 Waveform emphasis means 22 Boost setting means 23 Gain adjustment means 30 Delay element 31 Multiplier 32a Adder 32b Amplifier 33 Amplitude level detection means 34 Slicer 35 Reference memory 41 Interpolation means 51 Attenuation amount determination means 73 Signal characteristic detection means 74 Comparison means 75 Ideal signal memory 76 Boost control signal generation means

Claims (10)

A filter for equalizing the waveform of the signal;
Decoding means for decoding the output signal of the filter;
Adaptive control means for adaptively adjusting the characteristics of the filter based on input / output signals of the decoding means;
A signal inspection means for inspecting the quality of the received signal;
Boost setting means for outputting a boost control signal indicating an amount to be boosted and a band to be boosted according to the output of the signal inspection means;
Waveform shaping means for shaping the received signal according to the boost control signal and adjusting the amplitude level of the received signal;
A receiving circuit, wherein an output signal of the waveform shaping means is input to the filter. Gain adjusting means for adjusting the amplitude level of the signal according to the result of waveform equalization;
A filter for equalizing the waveform of the output signal of the gain adjusting means;
Decoding means for decoding the output signal of the filter;
Adaptive control means for adaptively adjusting the characteristics of the filter based on input / output signals of the decoding means;
Boost setting means for outputting a boost control signal indicating an amount to be boosted and a band to be boosted according to the output of the gain adjusting means;
Waveform emphasizing means for shaping the received signal according to the boost control signal,
A receiving circuit, wherein an output signal of the waveform enhancing means is inputted to the gain adjusting means. The receiving circuit according to claim 1,
The signal inspecting means observes the amplitude of the received signal and outputs the difference from the ideal amplitude level as an attenuation level signal, and ranks n attenuation level signals (n is an integer of 2 or more). It consists of a slicer classified as one of
The boost setting means includes a reference memory that holds boost control signals indicating n combinations of boost amounts and boost bands, and selects and outputs boost control signals corresponding to ranks determined by the slicer. A receiving circuit characterized. The receiving circuit according to claim 1,
The signal inspection means comprises amplitude level detection means for observing the amplitude of the received signal and outputting the difference from the ideal amplitude level as an attenuation level signal,
The boost setting means holds a boost control signal indicating n combinations (n is an integer of 2 or more) of a boost amount and a boost band, and selects and outputs the boost control signal held according to the attenuation level signal. And a interpolation circuit for performing a predetermined correction on the boost control signal output from the reference memory based on the attenuation level signal and outputting the corrected control signal. The receiving circuit according to claim 1,
The signal inspection means observes the frequency spectrum of the received signal, calculates the ratio of the spectral intensity in the low frequency region and the spectral intensity in the high frequency region, and calculates the spectral intensity in the low frequency region and the spectral intensity in the high frequency region in an ideal state. An attenuation amount determining means that outputs an attenuation level signal in comparison with the ratio of the above, and a slicer that classifies the attenuation level signal into one of n ranks (n is an integer of 2 or more),
The boost setting means includes a reference memory that holds boost control signals indicating n combinations of boost amounts and boost bands, and selects and outputs a boost control signal corresponding to a rank determined by the slicer. A receiving circuit. The receiving circuit according to claim 1,
The signal inspection means observes the frequency spectrum of the received signal, calculates the ratio of the spectral intensity in the low frequency region and the spectral intensity in the high frequency region, and calculates the spectral intensity in the low frequency region and the spectral intensity in the high frequency region in an ideal state. It is composed of attenuation determination means that outputs an attenuation level signal in comparison with the ratio of
The boost setting means holds a boost control signal indicating n combinations (n is an integer of 2 or more) of a boost amount and a boost band, and selects and outputs the boost control signal held according to the attenuation level signal. And a interpolation circuit for performing a predetermined correction on the boost control signal output from the reference memory based on the attenuation level signal and outputting the corrected control signal. The receiving circuit according to claim 1,
The signal inspection means amplifies the amplitude of the received signal to an ideal state amplitude, extracts a frequency spectrum, compares it with the frequency spectrum in the ideal state, and outputs it as an attenuation level signal; and the attenuation level signal a slicer that classifies one of n ranks (n is an integer of 2 or more),
The boost setting means includes a reference memory that holds boost control signals indicating n combinations of boost amounts and boost bands, and selects and outputs boost control signals corresponding to ranks determined by the slicer. A receiving circuit characterized. The receiving circuit according to claim 1,
The signal inspection means is composed of attenuation determination means for amplifying the amplitude of the reception signal to an amplitude in an ideal state, extracting a frequency spectrum and comparing it with the frequency spectrum in an ideal state and outputting it as an attenuation level signal,
The boost setting means holds a boost control signal indicating n combinations (n is an integer of 2 or more) of a boost amount and a boost band, and selects and outputs the boost control signal held according to the attenuation level signal. And a interpolation circuit for performing a predetermined correction on the boost control signal output from the reference memory based on the attenuation level signal and outputting the corrected control signal. The receiving circuit according to claim 1,
The signal inspection unit includes an ideal signal memory that holds an ideal frequency spectrum of a training signal, a signal characteristic detection unit that observes a frequency component of the reception signal and normalizes the frequency component according to the output of the ideal signal memory, and the signal characteristic Comparing the output of the detection means and the output of the ideal signal memory, the comparison means for outputting the difference of the frequency spectrum,
2. The receiving circuit according to claim 1, wherein the boost setting means comprises boost control signal generation means for controlling the characteristics of the waveform shaping means based on the frequency spectrum difference. The receiving circuit according to claim 1 or 2,
The boost setting means operates for a specific period within a training period of the filter, stops operating thereafter, and fixes the characteristics of the waveform shaping means or the waveform enhancement means.

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