JP2013201578A - Transmission line response estimator, and broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission line response estimator capable of enlarging a delay time range of transmission line response estimation, and suppressing degradation by multi-pass waves exceeding a time range capable of estimation, and a broadcast receiver.SOLUTION: The transmission line response estimator includes: a blind section for blinding reception signals; an FFT section for transforming blind section output to a frequency domain; a known pattern signal generation section for generating frequency domain signals of a known pattern; a transmission line response calculation section for calculating a transmission line response from FFT section output and known pattern frequency domain signals; an IFFT section for transforming output of the transmission line response calculation section to a time domain; an FFT window control section for generating a plurality of window signals of different widths or different widths and shift amounts for the blind section; a reception quality detection section for detecting reception quality using output of an equalization section for equalizing the reception signals in output of the IFFT section and thereafter; and an FFT window determination section for determining one with the excellent reception quality from a plurality of FFT windows on the basis of the reception quality detected for each of the plurality of different window signals.

Description

  Embodiments described herein relate generally to a transmission path response estimator and a broadcast receiving apparatus used in a receiver of a wireless system having a frame configuration in which known patterns are periodically inserted.

  In order to compensate for multipath distortion and the like based on a multipath transmission path in wireless transmission, there is a wireless system that performs transmission path response estimation by periodically transmitting a known pattern.

  In a digital terrestrial broadcasting system in the People's Republic of China (hereinafter abbreviated as China), a transmission frame is composed of a frame header (hereinafter referred to as FH) having a known pattern such as a PN sequence and a frame body (hereinafter referred to as FB) for transmitting data. Is done. Three types of FH length (number of symbols) are defined, 420, 595, and 945, and the length of FB is 3780. For example, Patent Document 1 discloses a technique for estimating a transmission line response in a frequency domain using a known pattern in a receiving apparatus that receives such a signal.

  In Patent Document 1, a channel response estimator that estimates a channel response includes a first FFT unit that converts a received signal into a frequency domain, a second FFT unit that converts a known pattern signal into a frequency domain, A transmission path response calculation section that calculates a transmission path response by dividing the output of the first FFT section by the output of the second FFT section; an IFFT section that converts the output signal of the transmission path response calculation section into a time domain; A delay time estimation unit that estimates a delay time from the output of the IFFT unit, and an FFT parameter determination unit that determines an FFT window position and an FFT size according to the delay time estimated by the delay time estimation unit. The first and second FFT units and IFFT units are processed based on the FFT window position and FFT size determined by the FFT parameter determination unit 106.

  The maximum value of the FFT size in the channel response estimation is determined by the temporal spread (hereinafter referred to as delay spread) of the assumed multipath wave (delayed wave). The FFT window position is set so as to include the delayed delayed wave FH.

  When trying to widen the delay time range for channel response estimation, it is necessary to increase the FFT size and perform FFT including long delay (hereinafter referred to as long delay) FH. Conventionally, an FFT with a maximum of 2048 points is used, but if a 4096-point FFT is used, the delay time range for channel response estimation can be expanded.

  Therefore, in a circuit that estimates a channel response in the frequency domain for a frame-structured signal in which known patterns are periodically inserted, the delay time range for channel response estimation can be expanded, and There is a demand for the realization of a transmission path response estimator that can suppress deterioration due to an excess multipath wave and can also reduce the influence of noise.

JP 2011-35790 A

  The problem to be solved by the present invention is that the delay time range of channel response estimation can be expanded in a circuit that estimates the channel response in the frequency domain for a frame-structured signal in which known patterns are periodically inserted. It is another object of the present invention to provide a transmission path response estimator and a broadcast receiving apparatus that can suppress deterioration due to multipath waves exceeding an estimable time range and can further reduce the influence of noise.

  An equalization apparatus according to an embodiment of the present invention provides a windowing method for windowing a received signal in a transmission path response estimator of a receiver that receives a signal having a frame structure in which a known pattern signal and a data signal are periodically transmitted. Unit, an FFT unit that converts the output of the windowing unit into a frequency domain, a known pattern signal generation unit that generates a frequency domain signal of a known pattern, and an output from the FFT unit and a frequency domain signal of the known pattern A transmission path response calculation section for calculating a path response; an IFFT section for converting the output of the transmission path response calculation section into a time domain; and a plurality of FFT windows having different widths or widths and shift amounts with respect to the windowing section Is generated and supplied to the windowing unit, and an FFT window control unit that sets one FFT window determined as the FFT window to the windowing unit, and equalization of the received signal at the output of the IFFT unit Part A reception quality detection unit that detects reception quality using the demodulated output of the received signal, and receives a plurality of different window signals from a plurality of FFT windows based on the reception quality detected by the reception quality detection unit. An FFT window determination unit that determines one having good quality and notifies the FFT window control unit of the one.

The block diagram of the transmission-line response estimator of the 1st Embodiment of this invention. Explanatory drawing of FFT window control of 1st Embodiment. The block diagram of the transmission line response estimator of the 2nd Embodiment of this invention. Explanatory drawing of the FFT window control of 2nd Embodiment. The block diagram of the transmission line response estimator of the 3rd Embodiment of this invention. The block diagram of the transmission line response estimator of the 4th Embodiment of this invention. The block diagram of the transmission-line response estimator of the 5th Embodiment of this invention. The block diagram of the transmission line response estimator of the 6th Embodiment of this invention. The block diagram of the broadcast receiver which concerns on one Embodiment of this invention. Transmission frame configuration (time domain signal) diagram in a digital terrestrial broadcasting system in China. The figure explaining the subject at the time of using 4096 point FFT, and its solution.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Before describing an embodiment of the present invention, a transmission frame configuration in a digital terrestrial broadcasting system in China will be described with reference to FIG.
A transmission frame is composed of a frame header (FH) of a known pattern such as a PN sequence and a frame body (FB) for transmitting data, and the length (number of symbols) of FH is defined by three types: 420, 595, and 945. The FB length of the data portion is 3780.

  Since the feature of the embodiment of the present invention relates to the control of the FFT window in the transmission line response estimation, in the following embodiment, the FFT / IFFT size is fixed at, for example, 4096 points, and the width and position of the FFT window are A configuration for setting and its operation will be described. Note that when the delay spread of the received signal is narrow and the FFT window can be narrowed, it is clear that the FFT size can be reduced within a range in which the received signal having the FFT window width can be accommodated.

[First Embodiment]
FIG. 1 is a block diagram of a transmission path response estimator according to the first embodiment of the present invention, and FIG. 2 is an explanatory diagram of FFT window control according to the first embodiment.
In FIG. 1, a channel response estimator 10A is provided in a receiver that receives a frame-structured signal in which a known pattern signal and a data signal are periodically transmitted. Specifically, the transmission path response estimator 10A is provided together with the equalization unit 19 and the error correction unit 20 in the equalization device 4 in the demodulation circuit 5 of the broadcast reception device in FIG. 10, for example. That is, the channel response estimator 10A constitutes the equalization apparatus 4 (see FIG. 9) together with the equalization unit 19 and the error correction unit 20.

  The transmission path response estimator 10A includes a windowing section 11, a first FFT section 12, a second FFT section 13, a transmission path response calculation section 14, an IFFT section 15, and an FFT window width control section 16. The reception quality detection unit 17 and the FFT window determination unit 18 are provided.

The windowing unit 11 performs windowing in a range including a known pattern of the received signal.
The first FFT unit 12 converts the output of the windowing unit 11 into the frequency domain.
The second FFT unit 13 converts the known pattern from the known pattern generation unit 21 into the frequency domain. The known pattern generation unit 21 and the second FFT unit 13 constitute a known pattern signal generation unit that generates a frequency domain signal of a known pattern. The known pattern signal generation unit may prepare a known pattern in the frequency domain in advance.

The transmission line response calculation unit 14 calculates a transmission line response from the output of the first FFT unit 12 and the output of the second FFT unit 13.
The IFFT unit 15 converts the output of the transmission path response calculation unit 14 into the time domain.
The FFT window width control unit 16 serving as the FFT window control unit generates a plurality of FFT windows having different widths with respect to the windowing unit 11, supplies the FFT windows to the windowing unit 11, and determines one FFT window determination unit 18 to determine The FFT window is set in the window hanging portion 11.

The reception quality detection unit 17 detects the reception quality using the demodulated output from the equalization unit 19 after equalizing the reception signal by the output of the IFFT unit 15.
For each of a plurality of different window signals, the FFT window determination unit 18 determines one of the plurality of FFT windows having good reception quality based on the reception quality detected by the reception quality detection unit 17, and performs FFT. The window width control unit 16 is notified.
In the above configuration, the FFT window width control unit 16 has a function of generating a plurality of FFT windows having different widths. The received signal is multiplied by an FFT window supplied from the FFT window width control unit 16 and is input to the first FFT unit 12 as 0 except for the FFT window width.

  FIG. 2 shows an example of switching the FFT window width. The minimum value of the FFT window width needs to be equal to or greater than the FH width so that the FH of the received signal can be accommodated. If there is no multipath wave (delayed wave), it is better to make it as narrow as possible to prevent interference due to FB. Further, the maximum value of the FFT window width when there is a multipath wave defines the delay time range for channel response estimation. Therefore, as the types of FFT window widths, for example, as shown in FIG. 2, there are three types of minimum (near the FH width), middle, and maximum (near the maximum FFT size). When a part of the reference known pattern is used for channel response estimation, the minimum window width can be further narrowed accordingly.

  FIG. 2 shows the FFT window when there is no multipath wave in the received signal, but when there is a multipath wave, the FFT window is defined based on the signal determined as the main wave from the received power.

  Next, a method for determining the FFT window will be described. In FIG. 1, an FFT window width control unit 16 sequentially generates a plurality of FFT windows (for example, windows 1, 2, and 3) having different widths at the start of channel response estimation. The equalizer 4 performs transmission path response estimation / equalization / error correction for each FFT window. The reception quality detection unit 17 detects reception quality using the equalized output or error correction output for each FFT window. For detection of reception quality, both equalized output and error correction output may be used.

  Examples of reception quality include modulation error ratio (MER) for equalized output and error rate for error correction output. The FFT window determination unit 18 determines one FFT window with good reception quality among the plurality of window widths, in particular, an FFT window with the best reception quality. After the determination by the FFT window determination unit 18 is completed, the FFT window width control unit 16 sets the determined FFT window in the windowing unit 11, thereby using the set FFT window and the transmission path response calculation unit 14. The transmission path response is estimated at.

 In the present embodiment, it is preferable that determination (determination) and setting of a suitable FFT window for the window hanging unit is performed as an initial setting before starting reception such as when the receiver is turned on. Even after the FFT window is determined and set, the reception quality detection is continued, and if the reception quality becomes worse than a predetermined value, the FFT window determination unit 18 determines that the reception state has changed. It can also be configured to perform the FFT window determination again. However, since one channel response estimator 10A is used for both channel response estimation for equalization and FFT window estimation, both estimations are performed stably, and the reception situation changes. In order to improve the following capability, it is possible to adopt a configuration using two transmission path response estimators as described in the fifth embodiment of FIG.

Here, a problem when the 4096-point FFT described in the background art is used will be described. That is, when performing FFT in a wide range like 4096 point FFT, there are the following problems.
FIG. 11 shows a case where there are two main and delayed waves in the received signal. (A) is when the delay time of the delayed wave exceeds 1/2 of the transmission frame length (the sum of FH and FB) but within the 4096 point FFT window, (b) exceeds the 4096 point FFT window. Show the case. It should be noted that in the relationship between the main wave and the delayed wave obtained by delaying the main wave, the frames having the FHs shown with diagonal lines in the figure indicate that they are the main wave and the delayed wave of the same frame.

The problem when the delay time exceeds 1/2 of the frame period as in (a) is that it is impossible to distinguish between the preceding wave and the delayed wave, and it is therefore a problem to set the FFT window correctly.
The problem when the delay time exceeds the transmission path response estimation range (FFT window width) as shown in (b) is that when a wide window is used, the folded delayed wave interferes, that is, the path that cannot be equalized interferes. The challenge is to become.

  When the delay spread exceeds 1/2 of the transmission frame length (the sum of FH and FB), it is impossible to distinguish between the preceding wave and the delayed wave by the determination using the delay profile as shown in (a). For this reason, when it is regarded as a delayed wave as shown in (a-1), the transmission path can be correctly estimated. However, when it is mistakenly regarded as a preceding wave as shown in (a-2), the reception characteristics are greatly deteriorated.

When the delay spread exceeds the 4096 point FFT window as in the case of (b), if a wide FFT window is used, the folded delayed wave becomes a disturbance as shown in (b-1), and the result of the transmission path estimation is to degrade. In this case, as shown in (b-2), it is possible to perform transmission path estimation within a range that does not include a folded delayed wave by using a narrow FFT window.
When the delay spread is small, it is desirable to use an FFT window that is as narrow as possible within a range in which the delay spread falls within the range in order to reduce the influence of FB and noise.

  According to the first embodiment, even when the delay spread changes without determining the delay time, it is possible to automatically switch to the FFT window width that provides the best reception quality of the received signal. Even when the delay time exceeds the maximum FFT window and the transmission path response cannot be estimated, it is possible to automatically select a narrow FFT window based on the reception quality result and suppress deterioration due to aliasing. That is, it is possible to expand the delay time range for channel response estimation and suppress deterioration due to multipath waves exceeding the time range in which channel response estimation is possible.

[Second Embodiment]
FIG. 3 is a block diagram of a transmission path response estimator according to the second embodiment of the present invention, and FIG. 4 is an explanatory diagram of FFT window control according to the second embodiment. The configuration of FIG. 3 is different from FIG. 1 in that an FFT window width / shift control unit 16A is used instead of the FFT window width control unit 16 in FIG. In the following, description of the same parts as those in FIGS. 1 and 2 is omitted, and different parts will be described.

  In the transmission path response estimator 10B of FIG. 3, the FFT window width / shift control unit 16A as the FFT window control unit generates a plurality of FFT windows whose positions are shifted in addition to the plurality of FFT windows having different widths. For example, in addition to a plurality of FFT windows 1, 2, 3a having different window widths, for example, two or more FFT windows 3b, 3c in which the position of the window 3a is shifted to change the position of the same width are generated.

  FIG. 4 shows an example of the FFT window shift. In order to expand the delay time range even when the delay spread is asymmetrical in the front-rear direction, an FFT window 3b shifted later in time and an FFT window 3c shifted forward are added to the FFT window 3a having the maximum width. In the example of FIG. 4, the FFT window is shifted in three stages, but may be further shifted in a plurality of stages. The other windows 1 and 2 may also be shifted.

  According to the second embodiment, the FFT window width can be switched according to the delay spread of the received signal without determining the delay time, and the delay time of the transmission path response estimation even when the delay spread is asymmetrical The range can be expanded. In addition, when the delay time exceeds the maximum FFT window and the transmission path response cannot be estimated, a narrow FFT window can be selected to suppress deterioration due to aliasing. That is, the delay time range for channel response estimation can be expanded, and the delay time range for channel response estimation that can be estimated can be expanded.

[Third Embodiment]
FIG. 5 is a block diagram of a transmission path response estimator according to the third embodiment of the present invention. The configuration of FIG. 5 is obtained by adding a delay time determination unit 22 and an FFT window correction unit 23 to the configuration of FIG. In the following, description of the same parts as in FIG. 1 will be omitted, and different parts will be described. Note that the transmission path response estimator in FIG. 3 may be configured to include the delay time determination unit 22 and the FFT window correction unit 23 as in FIG.

  In the channel response estimator 10C of FIG. 5, the delay time determination unit 22 as the delay spread determination unit is within the range of the FFT window width after the FFT window determination, and the time domain transmission channel response that is the output of the IFFT unit 15. The delay spread is estimated from the estimated value. When the delay spread estimated by the delay time determination unit 22 is narrower than the FFT window set by the FFT window width control unit 16, the FFT window correction unit 23 performs windowing according to the output of the delay time determination unit 22. The window width is corrected and the FFT window is further narrowed.

  According to the third embodiment, it is possible to improve the accuracy of channel response estimation by suppressing FB interference at the FFT input.

[Fourth Embodiment]
FIG. 6 is a block diagram of a transmission path response estimator according to the fourth embodiment of the present invention. The configuration of FIG. 6 is obtained by adding a delay time determination unit 2, an FFT window correction unit 23, and a correlation detection unit 24 to the configuration of FIG. In the following, description of the same parts as in FIG. 1 will be omitted, and different parts will be described. Note that the transmission path response estimator in FIG. 3 may also include a delay time determination unit 22, an FFT window correction unit 23, and a correlation detection unit 24, as in FIG.
In the channel response estimator 10D of FIG. 6, the correlation detection unit 24 detects a delay profile based on the correlation between the received signal and the known pattern in the time domain. The delay time determination unit 22 as the delay spread determination unit estimates the delay spread from the output of the correlation detection unit 24 within the range of the FFT window width after the FFT window determination. If the delay spread estimated by the delay time determination unit 22 is narrower than the FFT window set by the FFT window width control unit 16, the FFT window correction unit 23 performs windowing according to the output of the delay time determination unit 22. The window width is corrected and the FFT window is further narrowed.

  According to the fourth embodiment, it is possible to improve the accuracy of channel response estimation by suppressing FB interference at the FFT input. In addition, since the delay profile is detected by the correlation detection unit independently of the channel response estimation, the FFT follows the change in the delay spread of the received signal within the range of the FFT window width after the FFT window determination. A window can be set.

[Fifth Embodiment]
FIG. 7 is a block diagram of a transmission path response estimator according to the fifth embodiment of the present invention.
In FIG. 7, the equalization apparatus 4 includes an equalization unit 19, an error correction unit 20, a known pattern generation unit 21, and a transmission path response estimator 10E. The transmission path response estimator 10E includes a transmission path response estimator 10E-1 for FFT window control and a transmission path response estimator 10E-2 for data equalization.

  The transmission path response estimator 10E in FIG. 7 is different from the transmission path response estimator in FIG. 5 in that the transmission path response estimator 10E-1 for FFT window control and the transmission path response estimator 10E- for data equalization are used. 2 are provided independently. Each of the transmission path response estimators of FIGS. 1, 3, and 6 may also be configured to include two transmission path response estimators for FFT window control and data equalization as in FIG.

  The transmission path response estimator 10E-1 for FFT window control includes a windowing section 11, a first FFT section 12, a second FFT section 13, a transmission path response calculation section 14, an IFFT section 15, An equalization unit 19a, an FFT window width control unit 16, a reception quality detection unit 17, an FFT window determination unit 18, a delay time determination unit 22, and an FFT window correction unit 23 are provided. The function of the equalization unit 19a is the same as the function of the equalization unit 19.

  A transmission path response estimator 10E-2 for data equalization includes a windowing section 11a, a first FFT section 12a, a second FFT section 13a, a transmission path response calculation section 14a, an IFFT section 15a, It has. The functions of the windowing unit 11a, the first FFT unit 12a, the second FFT unit 13a, the transmission line response calculation unit 14a, and the IFFT unit 15a are respectively the windowing unit 11 and the first FFT unit. 12, the second FFT unit 13, the transmission line response calculation unit 14, and the IFFT unit 15.

  With this configuration, the FFT window can be determined simultaneously with data reception. By performing the FFT window determination at an appropriate fixed period, the FFT window can be set following the change in the delay profile of the received signal. In parallel with the equalization processing performed by the data channel equalization transmission path estimator 10E-2, the FFT window control transmission path response estimator 10E-1 calculates the width and position of the FFT window. Therefore, the FFT window can always be updated following changes in the delay profile of the received signal, and appropriate reception demodulation can be realized.

  In addition, it is clear that various modifications are possible, such as preparing a plurality of transmission path response estimators to speed up the FFT window determination time, and operating a plurality of transmission path response estimation units by time division multiplexing. .

  According to the fifth embodiment, the FFT window can be set following the change in the delay profile of the received signal, and the transmission path response is always estimated by the FFT window following the change in the received signal. Demodulation can be performed. It is particularly useful when mounted on a moving receiver.

[Sixth Embodiment]
FIG. 8 is a block diagram of a transmission path response estimator according to the sixth embodiment of the present invention.
The transmission path response estimator 10F of FIG. 8 is obtained by adding an FB replica generation unit 25 and an FB cancellation unit 26 to the input part of the transmission path response estimation in the configuration of the transmission path response estimator of FIG. Each of the transmission path response estimators of FIGS. 1, 3, 6, and 7 may have a configuration in which an FB replica generation unit 25 and an FB cancellation unit 26 are added similarly to FIG.

  When the FFT size is increased in order to increase the delay time, the amount of FB interference increases as the delay spread increases, and the accuracy of transmission path response estimation deteriorates. As a countermeasure, the received signal is demodulated and re-modulated using the transmission path response estimation result to create a replica of the data part (FB) (hereinafter referred to as FB replica), and the FB part from the received signal before the FFT input. A technique for canceling is known.

The operation will be described below.
In FIG. 8, at the start of operation, the transmission path response is estimated from the received signal including FH in the FB cancellation off state of the FB cancellation unit 26. Using the estimated transmission path response, the FB replica generation unit 25 demodulates and remodulates the received signal to generate a replica of the FB part. The generated FB replica is supplied to the FB cancellation unit 26, and the FB is canceled by subtracting the FB replica signal from the received signal. Thereafter, the transmission path response is estimated using the output of the FB cancellation. With the above operation, it is possible to perform transmission path response estimation with high accuracy while suppressing the influence of interference due to FB.

  According to the fifth embodiment, when the transmission path estimation of this embodiment is used, transmission path estimation is possible for a long delay multipath, and even when the delay time exceeds the transmission path estimation range. It is possible to minimize degradation of transmission path estimation.

  The FB section becomes noise for the transmission path estimation, but if the transmission path can be correctly estimated, the noise is reduced by the FB cancellation, and the accuracy of the transmission path estimation using the FB cancellation output is improved. On the other hand, if erroneous transmission path estimation is performed by loopback or the like, noise is added by FB cancellation, and transmission path estimation using the FB cancellation output further deteriorates. Since the transmission path estimation according to the embodiment of the present invention has an effect of not erroneously detecting a path, it can be said that the combination with the FB cancellation is effective.

[Seventh Embodiment]
FIG. 9 is a block diagram of a broadcast receiving apparatus according to an embodiment of the present invention. FIG. 9 is a block diagram of a broadcast receiving apparatus according to an embodiment equipped with the transmission path response estimators according to the first to sixth embodiments.

  The broadcast receiving apparatus 100 includes any one of the tuner 1 that selects and receives a broadcast signal and the transmission path response estimators 10A to 10F described in the first to sixth embodiments. And a demodulator circuit 5 that outputs demodulated data, a decoder 6 that decodes the demodulated data and reproduces a video signal and an audio signal, and a display unit 7 that outputs the reproduced video signal and audio signal. ing.

  The demodulation circuit 5 includes, for example, an A / D converter 2 that converts an IF signal from the tuner 1 into a digital signal, an orthogonal detector 3 that converts the digital IF signal into baseband I and Q signals, and a transmission line And an equalizer 4 that includes any one of the response estimators 10A to 10F and equalizes the received signal based on the result of channel response estimation. The equalization apparatus 4 includes an equalization unit 19 and an error correction unit 20 in addition to any one of the transmission path response estimators 10A to 10F. The decoder 3 includes, for example, a video decoder and an audio decoder.

  According to the broadcast receiving apparatus of such an embodiment, since any one of the transmission path response estimators 10A to 10F is provided, the delay time range of the transmission path response estimation can be expanded and the time that can be estimated Deterioration due to multipath waves exceeding the range can be suppressed, and the influence of noise can be reduced.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10A-10F ... Transmission path response estimator, 11 ... Windowing part, 12 ... 1st FFT part, 13 ... 2nd FFT part, 14 ... Transmission path response calculation part, 15 ... IFFT part, 16 ... FFT window width Control unit (FFT window control unit), 16A ... FFT window width / shift control unit (FFT window control unit), 17 ... Reception quality detection unit, 18 ... FFT window determination unit, 19 ... Equalization unit, 20 ... Error correction unit , 21 ... known pattern generation unit, 22 ... delay time determination unit (delay spread determination unit), 23 ... FFT window correction unit, 24 ... correlation detection unit, 25 ... FB replica generation unit, 26 ... FB cancellation unit.

Claims (5)

In a receiver channel response estimator that receives a frame-structured signal in which a known pattern signal and a data signal are periodically transmitted,
A windowing portion for windowing the received signal;
An FFT unit for converting the output of the windowing unit into a frequency domain;
A known pattern signal generator for generating a frequency domain signal of a known pattern;
A transmission line response calculation unit for calculating a transmission line response from the output of the FFT unit and the frequency domain signal of the known pattern;
An IFFT unit for converting the output of the transmission line response calculation unit into a time domain;
An FFT that generates a plurality of FFT windows having different widths or widths and shift amounts with respect to the windowing portion, supplies the FFT windows to the windowing portion, and sets one FFT window determined as the FFT window as the windowing portion. A window control unit;
A reception quality detection unit that detects reception quality using a demodulated output after the equalization unit that equalizes the reception signal at the output of the IFFT unit;
For each of a plurality of different window signals, one of the plurality of FFT windows having a good reception quality is determined based on the reception quality detected by the reception quality detection unit and notified to the FFT window control unit An FFT window determination unit to perform,
A transmission path response estimator characterized by comprising: In a receiver channel response estimator that receives a frame-structured signal in which a known pattern signal and a data signal are periodically transmitted,
A windowing portion for windowing the received signal;
An FFT unit for converting the output of the windowing unit into a frequency domain;
A known pattern signal generator for generating a frequency domain signal of a known pattern;
A transmission line response calculation unit for calculating a transmission line response from the output of the FFT unit and the frequency domain signal of the known pattern;
An IFFT unit for converting the output of the transmission line response calculation unit into a time domain;
An FFT that generates a plurality of FFT windows having different widths or widths and shift amounts with respect to the windowing portion, supplies the FFT windows to the windowing portion, and sets one FFT window determined as the FFT window as the windowing portion. A window control unit;
A reception quality detection unit that detects reception quality using a demodulated output after the equalization unit that equalizes the reception signal at the output of the IFFT unit;
A delay spread determining section that determines a delay spread of a received signal using an output of the IFFT section;
For each of a plurality of different window signals, one of the plurality of FFT windows having a good reception quality is determined based on the reception quality detected by the reception quality detection unit and notified to the FFT window control unit An FFT window determination unit to perform,
An FFT window correction unit that corrects the FFT window set in the windowing unit based on the output of the delay spread of the received signal determined by the delay spread determination unit within the range of the FFT window determined by the FFT window determination unit. When,
A transmission path response estimator. In a receiver channel response estimator that receives a frame-structured signal in which a known pattern signal and a data signal are periodically transmitted,
A windowing portion for windowing the received signal;
An FFT unit for converting the output of the windowing unit into a frequency domain;
A known pattern signal generator for generating a frequency domain signal of a known pattern;
A transmission line response calculation unit for calculating a transmission line response from the output of the FFT unit and the frequency domain signal of the known pattern;
An IFFT unit for converting the output of the transmission line response calculation unit into a time domain;
An FFT window control unit that generates a plurality of FFT windows having different widths or widths and shift amounts with respect to the windowing unit, and sets one FFT window determined as the FFT window as the windowing unit,
A reception quality detection unit that detects reception quality using a demodulated output after the equalization unit that equalizes the reception signal at the output of the IFFT unit;
A correlation detector for obtaining a time domain correlation between the received signal and the known pattern;
A delay spread determination unit that determines a delay spread of a received signal using an output of the correlation detection unit;
For each of a plurality of different window signals, one of the plurality of FFT windows having a good reception quality is determined based on the reception quality detected by the reception quality detection unit and notified to the FFT window control unit An FFT window determination unit to perform,
An FFT window correction unit that corrects the FFT window set in the windowing unit based on the output of the delay spread of the received signal determined by the delay spread determination unit within the range of the FFT window determined by the FFT window determination unit. When,
A transmission path response estimator. A replica generation unit that generates a replica signal of a data unit using the received signal and the output of the IFFT unit;
A cancellation unit for removing the data part from the received signal using the output of the replica generation unit,
The transmission path response estimator according to claim 1, wherein transmission path response estimation is performed using an output of the cancel unit. A tuner that selectively receives broadcast signals;
A demodulation circuit comprising the transmission path response estimator according to any one of claims 1 to 4, and equalizing a reception signal from the tuner and outputting demodulated data;
A decoder that decodes the demodulated data and reproduces a video signal and an audio signal;
A display unit for outputting the video signal and the audio signal;
A broadcast receiving apparatus comprising:

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