JP2012044483A - Receiving device and receiving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase in a circuit scale while maintaining impulse noise removing performance, when removing impulse noise from broadcast signals received by using antenna branches of a plurality of systems.SOLUTION: A receiving device is constituted as follows: an MRC section synthesizes broadcast signals, which are received by a plurality of antennas respectively, on a frequency domain; a noise removal processing section converts the synthesized post-synthesization signal to a signal in a time domain; a waveform of impulse noise is estimated on the basis of the converted post-synthesization signal; and after the estimated waveform is smoothed, the impulse noise included in the post-synthesization signal is detected on the basis of the smoothed waveform.

Description

  The present invention relates to a receiving apparatus and a receiving method for removing impulse noise from a broadcast signal subjected to orthogonal frequency division multiplexing modulation, and more particularly, to removing impulse noise from a broadcast signal received using a plurality of system antenna branches. The present invention relates to a receiving apparatus and a receiving method capable of suppressing an increase in circuit scale while maintaining noise removal performance.

  In a vehicle-mounted receiving apparatus that receives a broadcast signal such as a digital television broadcast wave, the reception performance is improved by receiving the broadcast signal by a plurality of antenna branches and synthesizing the received broadcast signals.

  In addition, the broadcast signal received by the in-vehicle receiver may be mixed with impulse noise mainly due to the start and stop of the electrical system. For this reason, in-vehicle receivers perform impulse noise removal processing for detecting impulse noise contained in the received broadcast signal and removing it from the broadcast signal.

  Here, in a vehicle-mounted receiving apparatus having a plurality of antenna branches, normally, impulse noise removal processing is performed for each antenna branch, and a broadcast signal after impulse noise removal is synthesized (see, for example, Patent Document 1).

JP 2008-283588 A

  However, if the impulse noise removal processing is performed for each antenna branch as in a conventional in-vehicle receiver, an impulse noise removal circuit must be provided for each antenna branch, which increases the circuit scale. There was a problem.

  Therefore, when removing impulse noise from a broadcast signal received using a plurality of system antenna branches, a receiving apparatus or receiving method capable of suppressing an increase in circuit scale while maintaining impulse noise removal performance. How to achieve it is a big issue.

  The present invention has been made to solve the above-described problems caused by the prior art, and has an impulse noise removal performance in the case of removing impulse noise from a broadcast signal received using a plurality of antenna branches. It is an object of the present invention to provide a receiving apparatus or a receiving method capable of suppressing an increase in circuit scale while maintaining.

  In order to solve the above-mentioned problems and achieve the object, the present invention is a receiving apparatus for receiving orthogonal frequency division multiplex modulated broadcast signals by a plurality of antennas, wherein the broadcast signals are respectively received by the plurality of antennas. A synthesis unit that synthesizes the signal in the frequency domain, and a waveform that estimates the waveform of the impulse noise based on the synthesized signal after conversion after converting the synthesized signal synthesized by the synthesis unit into a signal in the time domain An estimation means; a smoothing means for smoothing the waveform estimated by the waveform estimation means; and an impulse noise detection for detecting an impulse noise included in the synthesized signal based on the waveform smoothed by the smoothing means. Means.

  Further, the present invention is a receiving method for receiving orthogonal frequency division multiplexing modulated broadcast signals by a plurality of antennas, and combining the broadcast signals respectively received by the plurality of antennas on a frequency domain; The synthesized signal synthesized in the synthesizing step is converted into a signal in the time domain, the waveform estimating step for estimating the waveform of the impulse noise based on the synthesized signal after the transformation, and the waveform estimated in the waveform estimating step A smoothing step for smoothing; and an impulse noise detection step for detecting impulse noise included in the post-synthesis signal based on the waveform smoothed in the smoothing step.

  According to the present invention, broadcast signals respectively received by a plurality of antennas are synthesized on the frequency domain, the synthesized post-synthesis signal is converted into a signal in the time domain, and then based on the post-synthesized post-synthesis signal. Since the impulse noise waveform is estimated, the estimated waveform is smoothed, and the impulse noise included in the combined signal is detected based on the smoothed waveform, a plurality of antenna branches are used. In the case where impulse noise is removed from a broadcast signal received in this manner, an effect is obtained that an increase in circuit scale can be suppressed while maintaining the impulse noise removal performance.

FIG. 1 is a diagram showing an outline of a receiving method according to the present invention. FIG. 2 is a block diagram illustrating the overall configuration of the receiving apparatus according to the present embodiment. FIG. 3 is a block diagram showing detailed configurations of the MRC unit and the noise removal processing unit. FIG. 4 is a block diagram illustrating a detailed configuration of the noise detection unit. FIG. 5 is a diagram illustrating an example of a noise replica power value distribution before the smoothing process. FIG. 6 is a diagram illustrating an example of the noise replica power value distribution after the smoothing process. FIG. 7 is a flowchart illustrating a processing procedure performed by the noise detection unit. FIG. 8 is a flowchart illustrating another processing procedure performed by the noise detection unit.

  Exemplary embodiments of a receiving apparatus and a receiving method according to the present invention will be described below in detail with reference to the accompanying drawings. First, prior to detailed description of the embodiment, an outline of a reception method according to the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an outline of a receiving method according to the present invention.

  In addition, (A) in the figure shows a conventional configuration example and a configuration example according to the present invention, and (B) in the figure shows an outline of the smoothing process.

  As shown in FIG. 1A-1, in the conventional receiving apparatus, a noise removal processing unit is provided for each antenna branch (hereinafter simply referred to as “branch”). That is, in the conventional receiving apparatus, impulse noise removal processing is performed for each branch, and maximum ratio combining (MRC: Maximum Ratio Combining) is performed on the broadcast signal after impulse noise removal.

  However, providing a noise removing unit for each branch is not preferable because the circuit scale increases with an increase in the number of branches and the cost increases.

  Therefore, as shown in FIG. 1A-2, in the reception method according to the present invention, the impulse noise removal processing is performed after the maximum ratio combining of the broadcast signals from the respective branches. Specifically, in the receiving method according to the present invention, a noise removal processing unit is provided after the MRC unit that performs maximum ratio combining. With such a configuration, one noise removal processing unit is sufficient regardless of the number of branches, and thus an increase in circuit scale can be suppressed.

  However, if the impulse noise removal process is performed on the combined broadcast signal, the detection accuracy of the impulse noise may be reduced. This is because, as shown in (B-1) of FIG. 1, the waveform is varied by synthesizing a plurality of broadcast signals, and as a result, erroneous detection and detection omission of impulse noise are likely to occur.

  Therefore, in the receiving method according to the present invention, as shown in FIG. 1B-2, the synthesized signal is smoothed and then the impulse noise is detected.

  Specifically, in the reception method according to the present invention, the waveform of the impulse noise is estimated based on the combined signal, and the power value of the estimated waveform is calculated for each sample point. Further, in the reception method according to the present invention, the calculated power value is subjected to a moving average to suppress a variation in the waveform after the maximum ratio synthesis and correct the waveform to a smooth waveform. In the reception method according to the present invention, the sampling point where the impulse noise is mixed is detected based on the power value after the moving average.

  As described above, in the receiving method according to the present invention, the broadcast signals respectively received by the plurality of antennas are combined, the impulse noise waveform is estimated based on the combined signal, and the estimated waveform is smoothed. In addition, the impulse noise included in the post-synthesis signal is detected based on the smoothed waveform. Therefore, when removing impulse noise from a broadcast signal received using a plurality of system antenna branches, an increase in circuit scale can be suppressed while maintaining the impulse noise removal performance.

  In the reception method according to the present invention, the waveform of impulse noise in the time domain is estimated by converting the synthesized signal from the signal in the frequency domain to the signal in the time domain. Specifically, the reception technique according to the present invention has a novel configuration in that an IFFT (inverse Fourier transform) unit is provided after the MRC unit.

  Hereinafter, embodiments of a receiving apparatus and a receiving method to which the receiving method according to the present invention is applied will be described in detail. In the following, a case where the receiving apparatus according to the present invention is applied to an in-vehicle DTV (digital television) receiver will be described.

  First, the overall configuration of the receiving apparatus according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating the overall configuration of the receiving apparatus according to the present embodiment. In the figure, only components necessary for explaining the characteristics of the receiving apparatus are shown, and descriptions of general components are omitted.

  As shown in the figure, the receiving apparatus 10 corresponds to the branch 11-1 corresponding to the antenna 1, the branch 11-2 corresponding to the antenna 2, the branch 11-3 corresponding to the antenna 3, and the antenna 4. And a branch 11-4. The receiving apparatus 10 includes an MRC unit 12, a noise removal processing unit 13, an error correction unit 14, a TS generation unit 15, a video decoder 16, and an audio decoder 17.

  Each branch (11-1 to 11-4) includes a tuner 11a, an A (Analog) D (Digital) conversion unit 11b, an FFT (Fast Fourier Transform) unit 11c, and a transmission line equalization unit 11d. It has more. In the following, the branch 11-1 corresponding to the antenna 1 will be described, but the same applies to the other branches (11-2 to 11-4).

  The tuner 11a is a processing unit that detects and amplifies the broadcast signal from the antenna 1, and outputs the broadcast signal after detection and amplification to the AD conversion unit 11b. The AD conversion unit 11b converts the analog signal from the tuner 11a into a digital signal and outputs the digital signal to the FFT unit 11c.

  The FFT unit 11c is a processing unit that converts a signal in the time domain to a signal in the frequency domain by performing FFT (Fast Fourier Transform) processing on the broadcast signal input from the AD conversion unit 11b. Further, the FFT unit 11c outputs the broadcast signal after the FFT processing to the transmission path equalization unit 11d.

  The transmission line equalization unit 11d estimates the transmission line response for each carrier wave of the broadcast signal input from the FFT unit 11c, and based on the estimated transmission line response, the transmission line equalization unit 11d receives the broadcast signal input from the FFT unit 11c. A processing unit that performs equalization processing for correction.

  Further, the transmission path equalization unit 11 d outputs the broadcast signal after the equalization processing to the MRC unit 12. Note that the transmission path equalization unit 11d also outputs the estimated transmission path response to the MRC unit 12, which will be described later with reference to FIG.

  The MRC unit 12 performs a maximum ratio combining process on the broadcast signals received from the branches (11-1 to 11-4), and outputs the broadcast signal after the maximum ratio combination to the noise removal processing unit 13. It is.

  Note that the maximum ratio combining process is a process of combining the broadcast signals from the respective branches after performing weighting so that the combined S / N ratio is maximized.

  The noise removal processing unit 13 is a processing unit that detects impulse noise included in the broadcast signal received from the MRC unit 12 and removes the detected impulse noise from the broadcast signal. The noise removal processing unit 13 also performs a process of outputting the broadcast signal after impulse noise removal to the error correction unit 14. The detailed configurations of the MRC unit 12 and the noise removal processing unit 13 will be described later with reference to FIG.

  The error correction unit 14 calculates a provisional determination likelihood of each carrier after removing the impulse noise, performs an error correction process such as Viterbi decoding on the broadcast signal based on the calculated provisional determination likelihood, and after the error correction process Is a processing unit that outputs the broadcast signal to the TS generation unit 15. The TS generation unit 15 performs post-processing such as RS (Reed Solomon) decoding processing and interleaving processing on the error-corrected broadcast signal, and converts the post-processing broadcast signal into a TS packet format to generate a video decoder. 16 and a processing unit for outputting to the audio decoder 17.

  The video decoder 16 is a processing unit that extracts a video signal by decoding the broadcast signal output from the TS generation unit 15. The audio decoder 17 is a processing unit that extracts the audio signal by decoding the broadcast signal output from the TS generation unit 15. Note that the video signal extracted by the video decoder 16 and the audio signal extracted by the audio decoder 17 are output to an output device such as a display or a speaker.

  Here, detailed configurations of the MRC unit 12 and the noise removal processing unit 13 will be described with reference to FIG. FIG. 3 is a block diagram showing detailed configurations of the MRC unit and the noise removal processing unit.

  As shown in FIG. 3, the MRC unit 12 further includes a data combining unit 12a and a transmission path combining unit 12b. The noise removal processing unit 13 includes a demapping unit 13a, a mapping unit 13b, multiplication units 13c and 13d, IFFT units 13e and 13f, subtraction units 13g and 13i, a noise detection unit 13h, and an FFT unit 13j. And a transmission line equalization unit 13k.

  First, the detailed configuration of the MRC unit 12 will be described. The data combining unit 12a is a processing unit that combines the broadcast signals received from the branches (11-1 to 11-4) with a maximum ratio. The transmission line combining unit 12b is a processing unit that combines the transmission line responses received from the branches (11-1 to 11-4) with a maximum ratio.

  The broadcast signal synthesized by the data synthesis unit 12a (hereinafter referred to as “post-synthesis signal”) is output to the demapping unit 13a and the multiplication unit 13d, and the transmission path response (synthesized by the transmission path synthesis unit 12b ( Hereinafter, it is described as “post-combination transmission line response”), and is output to the multiplier 13c and the multiplier 13d.

  Next, a detailed configuration of the noise removal processing unit 13 will be described. The demapping unit 13a demaps each signal point of the synthesized signal input from the data synthesizing unit 12a onto a constellation represented by the in-phase component axis (I axis) and the quadrature component axis (Q axis), and the map unit 13b. It is a processing part which outputs to. Each signal point of the combined signal is demapped to a position closer to the reference point of each mapping frame on the constellation as the influence of noise or reflection received on the transmission path is lower.

  The mapping unit 13b performs mapping processing on the combined signal demapped by the demapping unit 13a and outputs the resultant signal to the multiplication unit 13c. The multiplying unit 13c is a processing unit that multiplies the broadcast signal input from the map unit 13b by the combined transmission path response input from the transmission path combining unit 12b. In addition, the multiplication unit 13c outputs a combined signal having transmission path characteristics to the IFFT unit 13e by such processing.

  The multiplication unit 13d is a processing unit that multiplies the combined signal input from the data combining unit 12a and the combined transmission path response input from the transmission path combining unit 12b. Further, the multiplication unit 13d outputs a combined signal having transmission path characteristics to the IFFT unit 13f by such processing.

  The IFFT unit 13e is a processing unit that converts the signal in the frequency domain into a signal in the time domain again by performing IFFT processing on the combined signal input from the multiplication unit 13c, and outputs the signal to the subtraction unit 13g. The IFFT unit 13f is a processing unit that converts the signal in the frequency domain into a signal in the time domain again by performing IFFT processing on the combined signal input from the multiplication unit 13d, and outputs the signal to the subtraction unit 13g.

  The subtracting unit 13g is a processing unit that subtracts the combined signal input from the IFFT unit 13e from the combined signal input from the IFFT unit 13f and outputs estimated waveform data obtained thereby to the noise detecting unit 13h.

  In other words, the noise removal processing unit 13 uses the combined signal (original data including impulse noise) obtained through the paths of the multiplying unit 13d and the IFFT unit 13f, and then the combined signal obtained through the paths of the demapping unit 13a to the IFFT unit 13e. The waveform of impulse noise is estimated by subtracting (temporary determination data restored as a broadcast signal at the time of transmission).

  The demapping unit 13a, the mapping unit 13b, the multiplication units 13c and 13d, the IFFT units 13e and 13f, and the subtraction unit 13g correspond to an example of a waveform estimation unit that estimates the waveform of impulse noise based on the combined signal.

  The noise detection unit 13h is a processing unit that detects impulse noise using the estimated waveform data input from the subtraction unit 13g. Hereinafter, the estimated waveform data input from the subtracting unit 13g is referred to as “noise replica”.

  Here, a detailed configuration of the noise detection unit 13h will be described with reference to FIG. FIG. 4 is a block diagram showing a detailed configuration of the noise detection unit 13h. As shown in the figure, the noise detection unit 13h further includes a power calculation unit 131, a buffer 132, a smoothing unit 133, and a detection processing unit 134.

  The power calculation unit 131 is a processing unit that calculates the power value of the noise replica (hereinafter referred to as “noise replica power value”) for each sample point. Specifically, the power calculation unit 131 calculates the sum of the square of the I-axis level and the square of the Q-axis level of the noise replica as the noise replica power value.

  In addition, the power calculation unit 131 stores the calculated noise replica power value in the buffer 132 and also performs processing for passing to the detection processing unit 134. The power calculation unit 131 also performs a process of notifying the smoothing unit 133 that the noise replica power value has been calculated.

  The buffer 132 is a temporary storage unit that stores the most recent noise replica power value among the noise replica power values calculated by the power calculation unit 131 by a predetermined number of samples. That is, the buffer 132 sequentially stores the latest noise replica power value by overwriting the oldest noise replica power value.

  The smoothing unit 133 is a processing unit that performs a noise replica power value smoothing process when a notification indicating that the noise replica power value has been calculated is received from the power calculation unit 131. Specifically, the smoothing unit 133 smoothes the noise replica power value by moving and averaging the noise replica power values stored in the buffer 132.

  The smoothing unit 133 also performs a process of outputting the noise replica power value after the moving average to the detection processing unit 134.

  Here, the smoothing unit 133 smoothes the noise replica power value by moving average, but the smoothing method is not limited, and smoothing is performed using other methods such as weighted average. May be performed.

  The detection processing unit 134 is a processing unit that detects a sample point mixed with impulse noise by comparing the noise replica power value after moving average input from the smoothing unit 133 with a predetermined threshold.

  When the detection processing unit 134 detects a sample point mixed with impulse noise, specifically, when the noise replica power value after the moving average is equal to or greater than the threshold, the moving average of the sample point The previous noise replica power value is output to the subtraction unit 13i. The noise replica power value before moving average is output from the power calculation unit 131.

  On the other hand, when the noise replica power value after moving average is less than the threshold, the detection processing unit 134 does not output the noise replica power value to the subtracting unit 13i.

  Here, an example in the case of performing the impulse noise detection process without performing the smoothing process on the noise replica power value will be described with reference to FIG. FIG. 5 is a diagram illustrating an example of a noise replica power value distribution before the smoothing process.

  The horizontal axis of the graph shown in the figure represents time (sample number), and the vertical axis represents the noise replica power value as a power level. Further, in the figure, it is assumed that impulse noise is mixed in the section of sample numbers “7” to “23”.

  As shown in FIG. 5, if the threshold value is set to the power level “4”, the detection processing unit 134 does not actually include impulse noise sample points “2”, “6”, “25”. Is determined as a sample point where a noise replica is mixed. In addition, the detection processing unit 134 samples the sample points “7”, “10”, “21”, and “23” in which impulse noise is mixed even though the impulse noise is actually mixed. It will be detected as a point.

  Note that by setting the threshold value to the power level “5”, it is possible to prevent erroneous detection of the impulse noise, but further detection omission of the sample point “19” where the impulse noise is actually mixed occurs. Become.

  As described above, when the detection process is performed without performing the smoothing process by the smoothing unit 133, it is easy to cause erroneous detection and detection omission of the impulse noise, so that the detection accuracy of the impulse noise may be lowered.

  On the other hand, an example in which impulse noise detection processing is performed after smoothing processing will be described with reference to FIG. FIG. 6 is a diagram illustrating an example of the noise replica power value distribution after the smoothing process.

  As shown in the figure, the distribution of the noise replica power value is smoothed by performing the smoothing process. The detection processing unit 134 performs impulse noise detection processing using the smoothed noise replica power value.

  For example, if the threshold value is set to the power level “4”, the detection processing unit 134 does not erroneously detect the impulse noise, and most of the sample points where the impulse noise is actually mixed (sample point “7”). To “22”) can be detected.

  Thus, by performing the impulse noise detection process after performing the smoothing process, it is possible to prevent a decrease in the detection accuracy of the impulse noise even when the impulse noise is removed after the maximum ratio synthesis.

  Returning to FIG. 3, the remaining components of the noise removal processing unit 13 will be described. The subtracting unit 13i is a processing unit that removes impulse noise from the combined signal by subtracting the noise replica power value input from the noise detecting unit 13h from the combined signal input from the IFFT unit 13f.

  Here, as described above, the noise replica power value input from the noise detection unit 13h is the noise replica power value before moving average. That is, in this embodiment, the noise replica power value after moving average is used as a noise replica power value for impulse noise detection, and the noise replica power value before moving average is used as a noise replica power value for impulse noise removal. Yes. This is because the noise replica power value before moving average is a value estimated as impulse noise.

  As described above, when the subtracting unit 13i detects the sample point mixed with the impulse noise by the detection processing unit 134 of the noise detecting unit 13h, the subtracting unit 13i uses the power value before the moving average at the sample point. Since the impulse noise is removed from the signal, the impulse noise can be appropriately removed.

  The subtracting unit 13i also performs a process of outputting the combined signal after removing the impulse noise to the FFT unit 13j.

  The FFT unit 13j is a processing unit that performs FFT processing on the combined signal input from the subtraction unit 13i to convert the signal in the time domain into a signal in the frequency domain, and outputs the signal to the transmission path equalization unit 13k. Also, the transmission line equalization unit 13k estimates the transmission line response for each carrier wave (carrier) of the combined signal input from the FFT unit 13i, and is input from the FFT unit 13i based on the estimated transmission line response. A processing unit that performs equalization processing to correct the combined signal.

  The transmission path equalization unit 13k also performs a process of outputting the combined signal after the equalization process to the error correction unit 14 illustrated in FIG.

  Next, a specific operation of the noise detection unit 13h will be described with reference to FIG. FIG. 7 is a flowchart illustrating a processing procedure performed by the noise detection unit 13h. Although the processing procedure for one sample point is shown in the figure, the noise detection unit 13h actually performs the processing shown in the figure for each sample point.

  As shown in FIG. 7, in the noise detection unit 13h, the power calculation unit 131 calculates the noise replica power value of the target sample point (step S101), and stores the calculated noise replica power value in the buffer ( Step S102).

  Subsequently, the smoothing unit 133 uses the noise replica power value stored in the buffer 132 to perform a moving average of the noise replica power value of the target sample point (step S103).

  Then, the detection processing unit 134 determines whether or not the noise replica power value after moving average is equal to or greater than the threshold (step S104). If the noise replica power value is equal to or greater than the threshold (step S104, Yes), the noise replica before moving average is determined. The power value is output to the subtracting unit 13i (step S105), and the process ends. On the other hand, when the noise replica power value after the moving average is not equal to or greater than the threshold (No in step S104), the detection processing unit 134 ends the process as it is.

  As described above, in the present embodiment, the MRC unit 12 combines broadcast signals respectively received by the plurality of antennas 1 to 4 on the frequency domain, and the noise removal processing unit 13 is combined by the MRC unit 12. The synthesized signal is converted into a signal in the time domain, the impulse noise waveform is estimated based on the converted synthesized signal, the smoothing unit 133 smoothes the estimated waveform, and the detection processing unit 134. However, the impulse noise included in the synthesized signal is detected based on the waveform smoothed by the smoothing unit 133.

  Therefore, when removing impulse noise from a broadcast signal received using a plurality of system antenna branches, an increase in circuit scale can be suppressed while maintaining the impulse noise removal performance.

  Further, the combined signal has the maximum S / N ratio by the maximum ratio combining (that is, the white noise (AWGN: Additive White Gaussian Noise) is reduced). When the white noise is reduced, the waveform of the impulse noise can be accurately estimated, and as a result, the detection accuracy of the impulse noise can be improved.

  In this embodiment, the power calculation unit 131 calculates a noise replica power value for each sample point, and the smoothing unit 133 performs noise averaging by moving and averaging the noise replica power value calculated by the power calculation unit 131. Since the replica power value is smoothed, the impulse noise can be detected in real time.

  In the embodiment described above, the detection processing unit 134 performs the impulse noise detection process for each sample point. However, the present invention is not limited to this. In other words, since the impulse noise waveform can be estimated in advance, if the period in which the impulse noise is mixed is known, the impulse noise waveform is subtracted from that period to obtain the impulse noise. It is also possible to remove.

  Therefore, hereinafter, a case where the noise detection unit 13h detects a section in which impulse noise is mixed will be described with reference to FIG. FIG. 8 is a flowchart showing another processing procedure performed by the noise detection unit 13h.

  As shown in the figure, in the noise detection unit 13h, the power calculation unit 131 calculates the noise replica power value of the target sample point (step S201), and stores the calculated noise replica power value in the buffer (step S201). Step S202). Further, the smoothing unit 133 uses the noise replica power value stored in the buffer 132 to perform a moving average of the noise replica power value at the target sample point (step S203).

  Subsequently, the detection processing unit 134 determines whether or not the noise replica power value after moving average is equal to or greater than a threshold value (step S204). When the noise replica power value after the moving average is equal to or greater than the threshold (Yes at Step S204), the detection processing unit 134 determines whether the section detection flag is in the ON state (Step S205). ), If it is not ON (step S205, No), the flag is set to ON (step S206), and the process returns to step S201. If the flag is in the ON state (step S205, Yes), the process returns to step S201 as it is.

  On the other hand, if the noise replica power value after moving average is not equal to or greater than the threshold (No in step S204), the detection processing unit 134 determines whether the flag is in an ON state (step S207). (Step S207, No), the process is returned to Step S201.

  Further, when the flag is in the ON state (step S207, Yes), the detection processing unit 134 sets the flag to OFF (step S208), and impulse noise is mixed in the section from the flag ON to the flag OFF. (Step S209), and the process ends.

  The section detected by the detection processing unit 134 is output to the subtracting unit 13i, and the subtracting unit 13i subtracts the impulse noise waveform data stored in advance in the storage unit (not shown) from the combined signal. do it.

  As described above, the receiving apparatus and the receiving method according to the present invention maintain the performance of removing impulse noise when removing impulse noise from a broadcast signal received using a plurality of systems of antenna branches, while maintaining the circuit scale. This is useful when it is desired to suppress the increase, and is particularly suitable for application to a vehicle-mounted receiving device.

1 to 4 antenna 10 receiving device 11-1 to 11-4 branch 12 MRC unit 12a data combining unit 12b transmission path combining unit 13 noise removal processing unit 13a demapping unit 13b map unit 13c, 13d multiplying unit 13e, 13f IFFT unit 13g, 13i subtraction unit 13h noise detection unit 131 power calculation unit 132 buffer 133 smoothing unit 134 detection processing unit 13j FFT unit 13k transmission path equalization unit 14 error correction unit 15 TS generation unit 16 video decoder 17 audio decoder

Claims (4)

A receiving device for receiving orthogonal frequency division multiplex modulated broadcast signals with a plurality of antennas,
Synthesizing means for synthesizing broadcast signals respectively received by the plurality of antennas on a frequency domain;
Waveform estimation means for estimating a waveform of impulse noise based on the combined signal after conversion after converting the combined signal combined by the combining means into a signal in the time domain;
Smoothing means for smoothing the waveform estimated by the waveform estimating means;
An impulse noise detecting means for detecting impulse noise included in the post-synthesis signal based on the waveform smoothed by the smoothing means. A power value calculating means for calculating a power value for each sampling point of the waveform estimated by the waveform estimating means,
The smoothing means includes
The receiving apparatus according to claim 1, wherein the waveform is smoothed by moving and averaging the power value calculated by the power value calculating unit. Impulse noise removing means for removing impulse noise from the broadcast signal using a power value before moving average at the sample point when a sample point mixed with impulse noise is detected by the impulse noise detecting means. The receiving apparatus according to claim 2, further comprising: A receiving method for receiving orthogonal frequency division multiplexing modulated broadcast signals with a plurality of antennas,
A combining step of combining broadcast signals respectively received by the plurality of antennas on a frequency domain;
A waveform estimation step of estimating a waveform of impulse noise based on the combined signal after the conversion after the combined signal combined in the combining means into a signal in the time domain;
A smoothing step of smoothing the waveform estimated in the waveform estimation step;
And an impulse noise detection step of detecting an impulse noise included in the post-synthesis signal based on the waveform smoothed in the smoothing step.

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