CN103326970B - Transmission path response estimator and broadcast receiver - Google Patents

Abstract

Provided are a channel response estimator and a broadcast receiving device capable of expanding a delay time range for channel response estimation and suppressing degradation due to multipath waves exceeding an estimated time range. The transmission path response estimator includes: a windowing unit for windowing the received signal; an FFT unit for converting the output of the windowing unit into the frequency domain; a known pattern signal generation unit; The mode frequency domain signal calculates the transmission path response; the IFFT part transforms the output of the transmission path response calculation part into the time domain; the FFT window control part generates multiple window signals with different widths or different widths and offsets to the windowing part; receiving The quality detection part detects the reception quality by using the output after the equalization part; and the FFT window judgment part determines an FFT window with good reception quality from a plurality of FFT windows based on the detected reception quality for each of the different window signals .

Description

Transmission path response estimator and broadcast receiving device

This application enjoys the priority of Japanese Patent Application No. 2012-068323 filed on March 23, 2012, and the entire content of the Japanese Patent Application is cited in this application.

technical field

Embodiments of the present invention relate to a channel response estimator and a broadcast receiving device used in a receiver of a wireless system having a frame structure in which a known pattern is periodically inserted.

Background technique

There is a wireless system that periodically transmits a known pattern to perform channel response estimation in order to compensate for multipath distortion due to multiple transmission paths in wireless transmission.

In the terrestrial digital broadcasting system of the People's Republic of China (hereinafter referred to as China), a transmission frame includes a frame header (hereinafter referred to as FH) of a known pattern such as a PN sequence and a frame body of transmission data (hereinafter referred to as FB). The length (number of symbols) of FH is stipulated in three types: 420, 595, and 945, and the length of FB is 3780. For example, Patent Document (Japanese Patent Application Laid-Open No. 2011-35790 ) describes a technique for estimating channel responses in the frequency domain using a known pattern in a receiving device receiving such a signal.

In the above patent document, the channel response estimator for estimating the channel response includes: a first FFT unit for converting a received signal into a frequency domain; a second FFT unit for converting a known pattern signal into a frequency domain; The section calculates the transmission path response by dividing the output of the first FFT section by the output of the second FFT section; the IFFT section transforms the output signal of the transmission path response calculation section into the time domain; an estimated delay time is output; and an FFT parameter determining unit determines an FFT window position and an FFT size according to the delay time estimated by the delay time estimating unit. The first and second FFT units and the IFFT unit perform processing based on the FFT window position and the FFT size determined by the FFT parameter determination unit.

Then, the maximum value of the FFT size in channel response estimation is determined using the estimated temporal spread of the multipath wave (delayed wave) (hereinafter referred to as delay spread). Also, the FFT window position is set to FH including the delayed wave.

In order to expand the delay time range of channel response estimation, it is necessary to increase the FFT size and perform FFT including FH with a long delay (hereinafter referred to as long delay). A maximum of 2048-point FFT has been used in the past, but if a 4096-point FFT is used, it is also possible to expand the range of delay time for transmission path response estimation.

Therefore, it is desired to realize a circuit for estimating a transmission channel response in the frequency domain to a frame structure signal in which a known pattern is periodically inserted, which can expand the delay time range of the transmission channel response estimation and suppress the exceeding of the estimated time. The propagation path response estimator that can reduce the influence of noise due to degradation caused by multiple waves in the range.

Contents of the invention

The technical problem to be solved by the present invention is to provide a circuit for estimating a transmission path response in the frequency domain for a frame structure signal in which a known pattern is periodically inserted, which can expand the delay time range of the transmission path response estimation, and can This is a transmission channel response estimator and broadcast receiving device that suppresses the degradation caused by multipath waves that exceed the estimated time range and can also reduce the influence of noise.

The transmission path response estimator of the first embodiment is characterized in that the transmission path response estimator of a receiver that receives a frame structure signal that periodically transmits a known pattern signal and a data signal includes: windowing A section, windowing the received signal within the range of a known pattern signal including the received signal; an FFT section, transforming the output of the windowed section into a frequency domain; a known pattern signal generation section, generating a frequency domain of a known pattern signal; the transmission path response calculation unit calculates the transmission path response based on the output of the FFT unit and the frequency domain signal of the known pattern; the IFFT unit transforms the output of the transmission path response calculation unit into the time domain; FFT The window control unit generates a plurality of FFT windows with different widths or different widths and offsets for the window adding unit, and provides them to the window adding unit, and sets one FFT window after the FFT window judgment is performed to the window adding unit. The windowing unit; the reception quality detection unit detecting the reception quality using the demodulation output after the equalization unit that equalizes the received signal through the output of the IFFT unit; For each window signal of the signal, one FFT window with good reception quality is determined from among a plurality of FFT windows based on the respective reception qualities detected by the reception quality detection unit, and notified to the FFT window control unit.

The transmission path response estimator of the second embodiment is characterized in that the transmission path response estimator of a receiver that receives a frame-structured signal that periodically transmits a known pattern signal and a data signal includes: Windowing the received signal within the range of the known mode signal including the received signal; the FFT unit transforms the output of the windowed unit into the frequency domain; the known mode signal generating unit generates the frequency domain signal of the known mode; a path response calculation section, calculating a transmission path response based on the output of the FFT section and the frequency domain signal of the known pattern; an IFFT section, converting the output of the transmission path response calculation section into a time domain; an FFT window control section , generating a plurality of FFT windows with different widths or different widths and offsets for the windowing unit, and providing them to the windowing unit, and setting one FFT window after the FFT window judgment is performed to the windowing unit A window unit; a reception quality detection unit that detects reception quality using a demodulated output after an equalization unit that equalizes a received signal through an output of the IFFT unit; a delay spread judgment unit that uses an output of the IFFT unit to judge reception quality. The delay spread of the signal; the FFT window judging section, for each of the different plurality of window signals, determines that the reception quality is good from among the plurality of FFT windows based on the respective reception qualities detected by the reception quality detection section 1 FFT window, and notifies the FFT window control unit; and the FFT window correction unit, within the range of the FFT window determined by the FFT window determination unit, within the range of the received signal determined by the delay spread determination unit When the delay spread output is narrower than the FFT window set for the windowing unit, correction is performed so that the FFT window set for the windowing unit is narrower.

The transmission path response estimator of the third embodiment is characterized in that the transmission path response estimator of a receiver that receives a frame-structured signal that periodically transmits a known pattern signal and a data signal includes: Windowing the received signal within the range of the known mode signal including the received signal; the FFT unit transforms the output of the windowed unit into the frequency domain; the known mode signal generating unit generates the frequency domain signal of the known mode; a path response calculation section, calculating a transmission path response based on the output of the FFT section and the frequency domain signal of the known pattern; an IFFT section, converting the output of the transmission path response calculation section into a time domain; an FFT window control section , generating a plurality of FFT windows with different widths or different widths and offsets for the windowing unit, and setting one FFT window after the FFT window judgment is performed to the windowing unit; the reception quality detection unit uses Use the output of the IFFT part to equalize the demodulation output after the equalization part of the received signal to detect the reception quality; the correlation detection part obtains the time domain correlation between the received signal and the known pattern; delay spread judgment A section, using the output of the correlation detection section, to judge the delay spread of the received signal; the FFT window judgment section, for each window signal of a plurality of different window signals, based on the respective received signals detected in the reception quality detection section quality, one FFT window with good reception quality is determined from a plurality of FFT windows, and notified to the FFT window control unit; and an FFT window correction unit is within the range of the FFT window determined by the FFT window judgment unit When the output of the delay spread of the received signal judged by the delay spread determination unit is narrower than the FFT window set for the windowing unit, correction is made so that the FFT window set for the windowing unit is narrower. narrow.

A broadcast receiving device according to another embodiment is characterized in that it includes: a tuner for selecting a channel to receive a broadcast signal; The tuner equalizes received signals and outputs demodulated data; the decoder decodes the demodulated data to reproduce video signals and audio signals; and the display unit outputs the video signals and audio signals.

Effect:

According to the channel response estimator and the broadcast receiving apparatus configured as above, in the circuit for estimating the channel response in the frequency domain with respect to the frame structure signal in which the known pattern is periodically inserted, it is possible to expand the delay time range of the channel response estimation, In addition, it is possible to suppress deterioration due to multipath waves exceeding the estimated time range, and to reduce the influence of noise.

Description of drawings

FIG. 1 is a block diagram of a channel response estimator according to the first embodiment of the present invention.

FIG. 2 is an explanatory diagram of FFT window control in the first embodiment.

Fig. 3 is a block diagram of a channel response estimator according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of FFT window control in the second embodiment.

FIG. 5 is a block diagram of a channel response estimator according to a third embodiment of the present invention.

FIG. 6 is a block diagram of a channel response estimator according to a fourth embodiment of the present invention.

Fig. 7 is a block diagram of a channel response estimator according to a fifth embodiment of the present invention.

FIG. 8 is a block diagram of a channel response estimator according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram of a broadcast receiving device according to an embodiment of the present invention.

Fig. 10 is a diagram of a transmission frame structure (time-domain signal) in a terrestrial digital broadcasting system in China.

FIG. 11 is a diagram illustrating problems and countermeasures when a 4096-point FFT is used.

detailed description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Before describing the embodiment of the present invention, the transmission frame structure in China's terrestrial digital broadcasting system will be described with reference to FIG. 10 .

The transmission frame includes the frame header (FH) of known modes such as PN sequence and the frame body (FB) of the transmission data. The length of FH (the number of symbols) is stipulated in three types: 420, 595, and 945, and the FB length of the data part is 3780. .

The feature of the embodiments of the present invention is the configuration related to the control of the FFT window in channel response estimation. Therefore, in the following embodiments, the FFT/IFFT size is fixed at, for example, 4096 points, and the width or position of the FFT window is used for The configuration and operation of the settings are described. Furthermore, it is obvious that when the delay spread of the received signal is narrowed so that the FFT window can be narrowed, the FFT size can also be reduced within the received signal range of the FFT window width.

[first embodiment]

FIG. 1 is a block diagram of a channel 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 transmission path response estimator 10A is provided in a receiver that receives a signal that periodically transmits a known pattern and a frame structure of a data signal. Specifically, the channel response estimator 10A is provided together with the equalizer 19 and the error corrector 20 in the equalizer 4 in the demodulation circuit 5 of the broadcast receiver shown in FIG. 9 , for example. That is, the channel response estimator 10A together with the equalizer 19 and the error corrector 20 constitute the equalizer 4 (see FIG. 9 ).

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

The windowing unit 11 performs windowing within a range including a known pattern of the received signal.

The first FFT unit 12 transforms the output of the windowing unit 11 into the frequency domain.

The second FFT unit 13 transforms the known pattern from the known pattern generation unit 21 into the frequency domain. Furthermore, the known pattern generating unit 21 and the second FFT unit 13 constitute a known pattern signal generating unit that generates a frequency domain signal of a known pattern. The known pattern signal generation unit may prepare known patterns in the frequency domain in advance.

The channel response calculation unit 14 calculates the channel response based on the output of the first FFT unit 12 and the output of the second FFT unit 13 .

The IFFT unit 15 transforms the output of the channel response calculation unit 14 into the time domain.

The FFT window width control unit 16 as the FFT window control unit generates a plurality of FFT windows with different widths for the window adding unit 11, and supplies them to the window adding unit 11, and sets one FFT window determined by the FFT window determining unit 18. Give the window part 11.

The reception quality detection unit 17 detects reception quality using the demodulated output from the equalizer unit 19 and subsequent ones that equalize the received signal with the output of the IFFT unit 15 .

The FFT window determination unit 18 determines one FFT window with good reception quality among the plurality of FFT windows based on the respective reception qualities detected by the reception quality detection unit 17 for each of the different plurality of window signals, And notify the FFT window width control unit 16 .

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 outputted to the first FFT unit 12 after adding an FFT window provided from the FFT window width control unit 16 to make the rest of the FFT window width 0.

Figure 2 shows an example of switching of the FFT window width. The minimum value of the FFT window width needs to be greater than the FH width, so that the FH of the received signal can be accommodated. In the absence of multipath waves (delayed waves), it is best to make them as narrow as possible to prevent interference from FB. In addition, the maximum value of the FFT window width in the case of multiple waves is a value that defines the delay time range for channel response estimation. Therefore, the types of FFT window widths are, for example, as shown in FIG. 2 , three types are the smallest (near the FH width), the middle, and the largest (near the largest FFT size). In addition, when a part of the known pattern used as a reference is used for channel response estimation, the minimum window width may be further narrowed in accordance with this case.

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

Next, a method of determining the FFT window will be described. In FIG. 1 , the FFT window width control unit 16 sequentially generates a plurality of FFT windows with different widths (for example, windows 1, 2, and 3) when channel response estimation starts. The equalizer 4 performs channel response estimation, equalization, and 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. It is also possible to use both the equalized output and the error-corrected output for detection of reception quality.

As an example of reception quality, there is Modulation Error Ratio (MER) for equalized output and Error Rate for error corrected output. The FFT window judging unit 18 judges one FFT window with good reception quality among a plurality of window widths, especially an FFT window with the best reception quality. After the judgment by the FFT window judging unit 18 ends, the FFT window width control unit 16 sets the judged FFT window to the windowing unit 11, and uses the set FFT window to perform the calculation in the transmission path response calculating unit 14. Transmission path answer presumption.

In the present embodiment, it is preferable to perform the determination (determination) and setting of the optimal FFT window for the above-mentioned windowing unit as an initial setting before the start of reception, such as when the receiver is powered on. Furthermore, it may be configured such that the reception quality detection is continued even after the determination and setting of the FFT window, and when the reception quality becomes worse than a predetermined value, the FFT window determination unit 18 determines that the reception state has expired. changes, thereby redoing the FFT window decision. However, since one channel response estimator 10A is used for both the channel response estimation for equalization and the estimation of the FFT window, it is necessary to perform both estimations stably and improve the response to changes in reception conditions. The follow-up performance may be configured using two transmission path response estimators as described in the fifth embodiment of FIG. 7 .

Here, problems when the 4096-point FFT described in the background art is used will be described. That is, when FFT is performed over a wide range such as 4096-point FFT, there are the following problems.

FIG. 11 shows a case where two waves, a main wave and a delayed wave, exist in a received signal. Part (a) in Figure 11 shows that the delay time of the delayed wave exceeds 1/2 of the transmission frame length (the sum of FH and FB), but it is within the FFT window of 4096 points, and (b) in Figure 11 Partially showing the case of an FFT window over 4096 points. In addition, in the relationship between the main wave and the delayed delayed wave, it is shown that the main wave and the delayed wave are the same frames in which the frame of FH with hatching in the figure is applied.

As shown in part (a) of FIG. 11 , when the delay time exceeds 1/2 of the frame period, there is a problem that it cannot be distinguished between the preceding wave and the delayed wave. Therefore, the problem is to set the FFT window correctly.

As shown in part (b) of FIG. 11, the problem when the delay time exceeds the channel response estimation range (FFT window width) is that a wide window is used. In this case, the problem is that the delayed wave that turns back becomes an obstacle , that is, paths that cannot be balanced become obstacles.

If the delay spread exceeds 1/2 of the transmission frame length (the sum of FH and FB), as shown in part (a) of Figure 11, it cannot be distinguished as the leading wave in the judgment using the delay profile Still a delayed wave. Therefore, when the delayed wave is regarded as shown in (a-1), the propagation path can be correctly estimated, but when the preceding wave is mistakenly regarded as shown in (a-2), the reception characteristic It deteriorates greatly.

In the case where the delay spread exceeds the 4096-point FFT window as shown in the case of part (b) in Fig. 11, if a wide FFT window is used, as shown in (b-1), the folded delayed wave becomes an obstacle , the result of propagation path estimation deteriorates. In this case, a narrow FFT window can be used as shown in (b-2), and channel estimation can be performed within a range that does not include a folded delayed wave.

In addition, in the case of small delay spread, in order to reduce the impact of FB or noise, it is desirable to use as narrow an FFT window as possible within the range of delay spread income.

According to the first embodiment, without judging the delay time, even when the delay spread changes, it is possible to automatically switch to the FFT window width that optimizes the reception quality of the received signal. Also, even when the delay time exceeds the maximum FFT window and channel response estimation cannot be performed, it is possible to automatically select a narrower FFT window based on the result of reception quality to suppress degradation due to loopback. That is, it is possible to expand the delay time range for propagation path response estimation, and to suppress deterioration due to multipath waves exceeding the time range for propagation path response estimation.

[Second Embodiment]

FIG. 3 is a block diagram of a channel response estimator according to a second embodiment of the present invention, and FIG. 4 is an explanatory diagram of FFT window control according to the second embodiment. The difference between the configuration of FIG. 3 and that of FIG. 1 is that an FFT window width/offset control unit 16A is used instead of the FFT window width control unit 16 in FIG. 1 . Hereinafter, the description of the same parts as those in FIGS. 1 and 2 will be omitted, and the different parts will be described.

In the channel response estimator 10B of FIG. 3 , the FFT window width and offset control unit 16A as the FFT window control unit generates a plurality of FFT windows whose positions are shifted in addition to a plurality of FFT windows having different widths. window. For example, in addition to a plurality of FFT windows 1, 2, and 3a having different window widths, two or more FFT windows 3b, 3c whose positions are shifted to have the same width, for example, are generated.

An example of FFT window shift is shown in FIG. 4 . In order to expand the delay time range even when the delay spread is asymmetrical, an FFT window 3 b shifted backward in time relative to the FFT window 3 a with the largest width and an FFT window 3 c shifted forward in time are added. In the example of FIG. 4, the FFT window is shifted in 3 stages, but it can also be shifted in more stages. In addition, it is also possible to make an offset relative to the other windows 1 and 2 .

According to the second embodiment, the FFT window width can be switched according to the delay spread of the received signal without judging the delay time, and the delay time range of channel response estimation can be enlarged even when the delay spread is asymmetrical. Also, when the delay time exceeds the maximum FFT window and channel response estimation cannot be performed, a narrower FFT window can be selected to suppress degradation due to turnaround. That is, the delay time range of channel response estimation can be expanded, and the delay time range of channel response estimation that can be estimated can be expanded.

[Third Embodiment]

FIG. 5 is a block diagram of a channel response estimator according to a third embodiment of the present invention. The configuration of FIG. 5 has a delay time determination unit 22 and an FFT window modification unit 23 added to the configuration of FIG. 1 . Hereinafter, the description of the same parts as those in FIG. 1 will be omitted, and the different parts will be described. Furthermore, the channel response estimator in FIG. 3 may also be configured to include a delay time determination unit 22 and an FFT window correction unit 23 as in FIG. 5 .

In the channel response estimator 10C of FIG. 5 , the delay time judging unit 22 as the delay spread judging unit determines the transmission channel in the instant domain based on the output of the IFFT unit 15 within the range of the FFT window width after the FFT window is judged. Respond to the estimated value to estimate the delay spread. When the delay spread estimated by the delay time judging unit 22 is narrower than the FFT window set in the FFT window width control unit 16, the FFT window correction unit 23 corrects the window width for windowing in accordance with the output of the delay time judging unit 22, Make the FFT window narrower.

According to the third embodiment, it is possible to suppress the interference of the FB in the FFT input and improve the accuracy of channel response estimation.

[Fourth Embodiment]

FIG. 6 is a block diagram of a channel response estimator according to a fourth embodiment of the present invention. The configuration of FIG. 6 adds a delay time determination unit 22 , an FFT window modification unit 23 , and a correlation detection unit 24 to the configuration of FIG. 1 . Hereinafter, the description of the same parts as those in FIG. 1 will be omitted, and the different parts will be described. Furthermore, the channel response estimator in FIG. 3 may be configured to include a delay time determination unit 22 , an FFT window correction unit 23 , and a correlation detection unit 24 in the same manner as in FIG. 6 .

In the channel response estimator 10D of FIG. 6 , the correlation detection unit 24 detects a delay profile using a correlation between a received signal and a known pattern in the time domain. The delay time determination unit 22 as a 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 has been performed. When the delay spread estimated by the delay time judging unit 22 is narrower than the FFT window set in the FFT window width control unit 16, the FFT window correction unit 23 corrects the window width for windowing in accordance with the output of the delay time judging unit 22, Make the FFT window narrower.

According to the fourth embodiment, it is possible to suppress the interference of FB in the FFT input and improve the accuracy of channel response estimation. In addition, since the delay profile is detected independently of the channel response estimation by the correlation detection unit, it is possible to set the delay profile following the change in the delay spread of the received signal if it is within the range of the FFT window width after the FFT window judgment. FFT window.

[Fifth Embodiment]

Fig. 7 is a block diagram of a channel response estimator according to a fifth embodiment of the present invention.

In FIG. 7 , the equalization device 4 includes an equalization unit 19 , an error correction unit 20 , a known pattern generation unit 21 , and a channel response estimator 10E. The channel response estimator 10E includes a channel response estimator 10E- 1 for FFT window control and a channel response estimator 10E- 2 for data equalization.

Compared with the configuration of the transmission channel response estimator 10E in FIG. 7, the transmission channel response estimator 10E-1 for FFT window control and the transmission channel response estimator 10E-1 for data equalization are independently provided. 2. Each of the channel response estimators in FIGS. 1 , 3 and 6 may be configured to include two systems of channel response estimators for FFT window control and data equalization, as in FIG. 7 .

The channel response estimator 10E-1 for FFT window control includes a windowing unit 11, a first FFT unit 12, a second FFT unit 13, a channel response calculation unit 14, an IFFT unit 15, an equalization unit 19a, and 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 . The function of the equalizer unit 19 a is the same as that of the equalizer unit 19 .

The channel response estimator 10E-2 for data equalization includes a windowing unit 11a, a first FFT unit 12a, a second FFT unit 13a, a channel response calculation unit 14a, and an IFFT unit 15a. The respective functions of the windowing unit 11a, the first FFT unit 12a, the second FFT unit 13a, the transmission path response calculation unit 14a, and the IFFT unit 15a are the same as those of the windowing unit 11, the first FFT unit 12, the second FFT unit 13, and the transmission path The functions of the response calculation unit 14 and the IFFT unit 15 are the same.

With this configuration, the determination of the FFT window can be performed simultaneously with data reception. By performing determination of the FFT window at an appropriate fixed cycle, it is possible to set the FFT window following changes in the delay profile of the received signal. When the equalization processing is performed in the transmission path response estimator 10E-2 for data equalization, the width or position of the FFT window is calculated in the transmission path response estimator 10E-1 for FFT window control in parallel. Therefore, it is possible to follow the reception The FFT window is frequently updated by changing the delay profile of the signal, enabling proper receive demodulation.

Furthermore, it is obvious that a plurality of channel response estimators may be prepared to advance the judgment time of the FFT window, or a plurality of channel response estimators may be time-division-multiplexed to perform various modifications.

According to the fifth embodiment, the FFT window can be set to follow the change of the delay profile of the received signal, and the channel response can be estimated using the FFT window which always follows the change of the received signal, thereby performing appropriate demodulation. Especially useful for piggybacking on mobile receivers.

[Sixth Embodiment]

FIG. 8 is a block diagram of a channel response estimator according to a sixth embodiment of the present invention.

Compared with the configuration of the channel response estimator 10F in FIG. 5 , the channel response estimator 10F in FIG. 8 has an FB replica generation unit 25 and an FB cancel unit 26 added to the channel response estimation input section. 1 , 3 , 6 , and 7 each of the channel response estimators may have a configuration in which the FB replica generation unit 25 and the FB cancel unit 26 are added in the same manner as in FIG. 8 .

When the FFT size is increased to increase the delay time, if the delay spread increases, the amount of FB interference increases, deteriorating the accuracy of channel response estimation. As a countermeasure against this, there is known a technique of demodulating and remodulating the received signal using the channel response estimation result, and making a replica of the data part (FB) (hereinafter referred to as FB replica), and at the stage before FFT input , to remove the FB part from the received signal.

The operation will be described below.

In FIG. 8 , when the operation starts, the FB cancellation unit 26 estimates the channel response from the received signal including the FH in the state that the FB is cancelled. Using the estimated channel response, the FB replica generation unit 25 demodulates and remodulates the received signal to generate a replica of the FB portion. The generated FB replica is supplied to the FB canceling unit 26, and the FB is canceled by removing the FB replica signal from the received signal. The output of the FB cancellation is used later to estimate the transmission path response. With the above operation, the influence of the interference caused by the FB can be suppressed, and highly accurate channel response estimation can be performed.

According to the fifth embodiment, when the propagation path estimation of the present embodiment is used, the propagation path estimation can be performed on long-delay multipaths, and even when the delay time exceeds the propagation path estimation range, the transmission path can be estimated. Deterioration of route estimation is suppressed to a minimum.

The FB portion becomes noise for channel estimation, but if the channel can be estimated correctly, the noise will be reduced by FB cancellation, and the accuracy of channel estimation using the FB cancellation output will be further improved. On the other hand, when an erroneous channel estimation is performed due to a retracement or the like, noise is conversely added by FB cancellation, and the channel estimation using the FB cancellation output further deteriorates. The propagation path estimation according to the embodiment of the present invention has the effect of not erroneously detecting paths, so it can be said that the combination with FB cancellation is effective.

[Seventh Embodiment]

FIG. 9 is a block diagram of a broadcast receiving device according to an embodiment of the present invention. FIG. 9 is a block diagram of a broadcast receiving device in which one embodiment of the channel response estimator according to the first to sixth embodiments is mounted.

The broadcast receiving device 100 includes: a tuner 1 for selecting a channel to receive a broadcast signal; The received signal is equalized to output demodulated data; the decoder 6 decodes the demodulated data to reproduce video signals and audio signals; and the display unit 7 outputs the reproduced video signals and audio signals.

The demodulation circuit 5 is provided with, for example: an A/D conversion unit, which converts the IF signal from the tuner 1 into a digital signal; a quadrature detection unit 3, which converts the digital IF signal into baseband I, Q signals; and an equalizer 4 , including any one of the channel response estimators 10A to 10F, which equalizes the received signal based on the result of the channel response estimation. The equalizer 4 includes an equalizer 19 and an error corrector 20 in addition to any one of the channel response estimators 10A to 10F. In addition, the decoder 3 includes, for example, a video decoder and an audio decoder.

According to such a broadcast receiving device of one embodiment, since any one of the channel response estimators 10A to 10F is provided, it is possible to expand the delay time range of the channel response estimation and to suppress multiple channels exceeding the estimated time range. The degradation caused by waves, and reduce the influence of noise.

Some embodiments of the present invention have been described above, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope or gist of the invention, and are also included in the invention described in the claims and their equivalents.

Claims (6)

1. a transmission path response estimator, is the transmission path response estimator of receiver, and the frame structure signal of cyclical transmission known mode signal and data signal is received by described receiver,

It is characterized in that, described transmission path response estimator has:

Windowing portion, docks collection of letters windowing including receiving in the range of the known mode signal of signal；

FFT portion, by the output transform in described windowing portion to frequency domain；

Known mode signal generating unit, generates the frequency-region signal of known mode；

Transmission path response calculating part, according to output and the frequency-region signal of described known mode in described FFT portion, calculates transmission path response；

IFFT portion, by the output transform of described transmission path response calculating part to time domain；

FFT window control portion, produces multiple FFT windows that width is different or width is different with side-play amount, and is supplied to described windowing portion described windowing portion, sets having carried out 1 FFT window after FFT window judges to described windowing portion；

Quality of reception test section, uses the later demodulation in the equilibrium portion number carrying out equalizing of collecting mail of the output docking by described IFFT portion to export, detects the quality of reception；With

FFT window judging part, for each window signal of different multiple window signals, according to the respective quality of reception detected in described quality of reception test section, determines 1 FFT window that the quality of reception is good among multiple FFT windows, and notifies to described FFT window control portion.

2. a transmission path response estimator, is the transmission path response estimator of receiver, and the frame structure signal of cyclical transmission known mode signal and data signal is received by described receiver,

It is characterized in that, described transmission path response estimator has:

Windowing portion, docks collection of letters windowing including receiving in the range of the known mode signal of signal；

FFT portion, by the output transform in described windowing portion to frequency domain；

Known mode signal generating unit, generates the frequency-region signal of known mode；

Transmission path response calculating part, according to output and the frequency-region signal of described known mode in described FFT portion, calculates transmission path response；

IFFT portion, by the output transform of described transmission path response calculating part to time domain；

FFT window control portion, produces multiple FFT windows that width is different or width is different with side-play amount, and is supplied to described windowing portion described windowing portion, sets having carried out 1 FFT window after FFT window judges to described windowing portion；

Quality of reception test section, uses the later demodulation in the equilibrium portion number carrying out equalizing of collecting mail of the output docking by described IFFT portion to export, detects the quality of reception；

Postpone extension judging part, use the output in described IFFT portion, it is judged that receive the delay extension of signal；

FFT window judging part, for each window signal of different multiple window signals, according to the respective quality of reception detected in described quality of reception test section, determines 1 FFT window that the quality of reception is good among multiple FFT windows, and notifies to described FFT window control portion；With

FFT window correction portion, in the range of the FFT window determined by described FFT window judging part, described postpone the output postponing extension receiving signal that extension judging part judges than set to the FFT window in described windowing portion narrow in the case of, be modified to set the FFT window to described windowing portion narrower.

3. a transmission path response estimator, is the transmission path response estimator of receiver, and the frame structure signal of cyclical transmission known mode signal and data signal is received by described receiver,

It is characterized in that, described transmission path response estimator has:

Windowing portion, docks collection of letters windowing including receiving in the range of the known mode signal of signal；

FFT portion, by the output transform in described windowing portion to frequency domain；

Known mode signal generating unit, generates the frequency-region signal of known mode；

Transmission path response calculating part, according to output and the frequency-region signal of described known mode in described FFT portion, calculates transmission path response；

IFFT portion, by the output transform of described transmission path response calculating part to time domain；

FFT window control portion, produces multiple FFT windows that width is different or width is different with side-play amount to described windowing portion, sets having carried out 1 FFT window after FFT window judges to described windowing portion；

Quality of reception test section, uses the later demodulation in the equilibrium portion number carrying out equalizing of collecting mail of the output docking by described IFFT portion to export, detects the quality of reception；

Coherent detection portion, asks for receiving the time domain between signal and described known mode relevant；

Postpone extension judging part, use the output in described coherent detection portion, it is judged that receive the delay extension of signal；

FFT window judging part, for each window signal of different multiple window signals, according to the respective quality of reception detected in described quality of reception test section, determines 1 FFT window that the quality of reception is good among multiple FFT windows, and notifies to described FFT window control portion；With

FFT window correction portion, in the range of the FFT window determined by described FFT window judging part, described postpone the output postponing extension receiving signal that extension judging part judges than set to the FFT window in described windowing portion narrow in the case of, be modified to set the FFT window to described windowing portion narrower.

4. according to the transmission path response estimator described in any one of claims 1 to 3, it is characterised in that possess:

Copy generating unit, uses and receives signal and the output in described IFFT portion, generates the replica signal of data portion；With

Elimination portion, uses the output of described copy generating unit, removes data portion from described reception signal,

This transmission path response estimator uses the output in described elimination portion to be transmitted path response presumption.

5. a broadcast receiver, it is characterised in that have:

Tuner, channel selection receives broadcast singal；

Demodulator circuit, possesses the transmission path response estimator described in any one of claims 1 to 3, by from the reception signal equalization of described tuner demodulated output data；

Decoder, is decoded described demodulating data, reproduces signal of video signal and acoustical signal；With

Display part, exports described signal of video signal and acoustical signal.

6. a broadcast receiver, it is characterised in that have:

Tuner, channel selection receives broadcast singal；

Demodulator circuit, possesses the transmission path response estimator described in claim 4, by from the reception signal equalization of described tuner demodulated output data；

Decoder, is decoded described demodulating data, reproduces signal of video signal and acoustical signal；With

Display part, exports described signal of video signal and acoustical signal.