WO2017104040A1 - Noise detection device, noise reduction device, and noise detection method - Google Patents
Noise detection device, noise reduction device, and noise detection method Download PDFInfo
- Publication number
- WO2017104040A1 WO2017104040A1 PCT/JP2015/085325 JP2015085325W WO2017104040A1 WO 2017104040 A1 WO2017104040 A1 WO 2017104040A1 JP 2015085325 W JP2015085325 W JP 2015085325W WO 2017104040 A1 WO2017104040 A1 WO 2017104040A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- noise
- frequency
- unit
- detection
- signal
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
Definitions
- the present invention relates to a noise detection device, a noise reduction device, a noise detection method and a noise detection program, and a recording medium on which the noise detection program is recorded.
- broadcast receivers that receive and process audio broadcast waves and output broadcast audio have become widespread.
- One of the noise sounds that may be included in the output sound from such a broadcast receiving apparatus is a so-called beat noise sound.
- the beat noise component that causes such beat noise is within the band of the audio signal, it is difficult to distinguish the audio component from the beat noise component. If it is a beat noise component derived from a fixedly arranged peripheral electronic device or the like, it is possible to reduce the beat noise sound by examining the frequency of the beat noise component in advance and reducing only the frequency component. . However, with this method, when beat noise components having various frequencies are mixed in from the surrounding environment, the beat noise sound cannot be reduced.
- the predetermined threshold when the energy value of the signal component in the frequency region other than the noise frequency region is high, if the predetermined threshold is constant, the frequency region other than the noise frequency region is erroneously detected as the noise frequency region. . For this reason, the predetermined threshold cannot be easily lowered.
- the energy value of the beat noise component also changes due to the change in the surrounding environment of the broadcast receiving apparatus that moves with the vehicle. For this reason, if the predetermined threshold is set high, a situation in which the beat noise component cannot be detected may occur.
- a frequency along the frequency axis for each second frequency width wider than the first frequency width is obtained by averaging the frequency components of the input signal for each first frequency width.
- a generation unit that generates a threshold curve based on a reference energy value obtained by averaging; a detection unit that detects, as a noise frequency region, a frequency region in which the time averaged result is an energy value exceeding the threshold curve;
- a noise detecting device comprising:
- the invention according to claim 6 is the noise detection device according to claim 1; and a reduction unit that reduces a noise frequency domain component detected by the noise detection device in a signal input to the noise detection device.
- a noise reduction device provided.
- the invention according to claim 7 is a noise detection method used in a noise detection apparatus including a generation unit and a detection unit, wherein the generation unit calculates a frequency component of an input signal for each first frequency width. Generating a threshold curve based on a reference energy value obtained by performing frequency averaging along the frequency axis for each second frequency width wider than the first frequency width with respect to the result of time averaging; And a detection step of detecting, as a noise frequency region, a frequency region in which the time averaged result has an energy value exceeding the threshold curve, as a noise detection method.
- the invention described in claim 8 is a noise detection program characterized by causing a computer included in the noise detection apparatus to execute the noise detection method according to claim 7.
- the invention described in claim 9 is a recording medium in which the noise detection program according to claim 8 is recorded so as to be readable by a computer included in the noise detection device.
- FIG. 3 is a diagram (part 1) for explaining signal processing in the noise detection apparatus of FIG. 2;
- FIG. 3 is a diagram (No. 2) for explaining signal processing in the noise detection apparatus of FIG. 2;
- It is a block diagram which shows roughly the structure of the broadcast receiving apparatus provided with the noise reduction apparatus which concerns on 2nd Embodiment of this invention.
- FIG. 1 It is a block diagram which shows the structure of the noise detection apparatus of FIG. It is a block diagram which shows roughly the structure of the broadcast receiving apparatus provided with the noise reduction apparatus which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structure of the reduction unit of FIG.
- FIG. 1 is a block diagram showing a schematic configuration of a broadcast receiving device 100A including a noise reduction device 140A according to the first embodiment of the present invention.
- the broadcast receiving device 100A includes an antenna 110, an RF processing unit 120, and a detection unit 130 in addition to the noise reduction device 140A.
- the broadcast receiving apparatus 100A includes an analog processing unit 160, a speaker unit 170, an input unit 180, and a control unit 190.
- the antenna 110 receives a broadcast wave.
- the reception result by the antenna 110 is sent to the RF processing unit 120 as a signal RFS.
- the RF processing unit 120 performs channel selection processing for extracting a signal of a desired station to be selected from the signal RFS in accordance with the channel selection command CSL sent from the control unit 190, and has a component in a predetermined intermediate frequency band. An intermediate frequency signal IFD is generated. Then, the RF processing unit 120 sends the generated intermediate frequency signal IFD to the detection unit 130.
- the RF processing unit 120 includes an input filter, a high-frequency amplifier (RF-AMP: Radio Frequency-Amplifier), and a band-pass filter (hereinafter also referred to as “RF filter”).
- the RF processing unit 120 includes a mixer (mixer), an intermediate frequency filter (hereinafter also referred to as “IF filter”), an AD (Analogue to Digital) converter, and a local oscillation circuit (OSC). Yes.
- the input filter is a high-pass filter that blocks low-frequency components of the signal RFS sent from the antenna 110.
- the high frequency amplifier amplifies the signal that has passed through the input filter.
- the RF filter selectively passes a signal in a high frequency band among signals output from the high frequency amplifier.
- the mixer mixes the signal that has passed through the RF filter and the local oscillation signal supplied from the local oscillation circuit.
- the IF filter selects and passes a signal in a predetermined intermediate frequency range among the signals output from the mixer.
- the AD converter converts the signal that has passed through the IF filter into a digital signal. This conversion result is sent to the detection unit 130 as an intermediate frequency signal IFD.
- the local oscillation circuit includes an oscillator that can control the oscillation frequency by voltage control or the like. This local oscillation circuit generates a local oscillation signal having a frequency corresponding to a desired station to be selected in accordance with a channel selection command CSL sent from the control unit 190, and supplies it to the mixer.
- the detection unit 130 receives the intermediate frequency signal IFD sent from the RF processing unit 120. Then, the detection unit 130 performs detection processing on the intermediate frequency signal IFD, and sends the detection result to the noise reduction device 140A as a detection signal DTD.
- the detection signal DTD is an audio band signal (audio signal).
- the noise reduction device 140A includes a noise detection device 150A and a reduction unit 156A.
- the noise detection device 150A receives the detection signal DTD sent from the detection unit 130. Then, the noise detection device 150A detects a noise frequency region that is a frequency region including a beat noise component in the detection signal DTD. The detection result by the noise detection device 150A is sent to the reduction unit 156A as noise frequency domain information NRI.
- the reduction unit 156A receives the detection signal DTD sent from the detection unit 130 and the noise frequency domain information NRI sent from the noise detection device 150A. Then, the reduction unit 156A reduces the noise frequency domain component indicated by the noise frequency domain information NRI in the detection signal DTD. As a result, the beat noise component in the detection signal DTD is reduced. The beat noise component reduction result by the reduction unit 156A is sent to the analog processing unit 160 as a signal AOD.
- the reduction unit 156A includes a variable notch filter in which the reduction region changes according to the noise frequency region information NRI.
- the analog processing unit 160 receives the signal AOD sent from the noise reduction device 140A. Then, the analog processing unit 160 generates an output audio signal AOS under the control of the control unit 190, and sends the generated output audio signal AOS to the speaker unit 170.
- the analog processing unit 160 having such a function includes a DA (Digital-to-Analogue) conversion unit, a volume adjustment unit, and a power amplification unit.
- the DA conversion unit receives the signal AOD sent from the noise reduction device 140A.
- the DA conversion unit converts the signal AOD into an analog signal.
- the analog conversion result by the DA conversion unit is sent to the volume adjustment unit.
- the volume adjuster receives the analog conversion result signal sent from the DA converter. Then, the volume adjustment unit performs volume adjustment processing on the signal of the analog conversion result in accordance with the volume adjustment command VLC from the control unit 190.
- the volume adjustment unit is configured to include an electronic volume element or the like. The signal of the volume adjustment result by the volume adjustment unit is sent to the power amplification unit.
- the power amplification unit receives the signal of the volume adjustment result sent from the volume adjustment unit.
- the power amplification unit power-amplifies the signal of the volume adjustment result.
- the power amplification unit includes a power amplifier.
- An output audio signal AOS that is an amplification result by the power amplification unit is sent to the speaker unit 170.
- the speaker unit 170 includes a speaker.
- the speaker unit 170 reproduces and outputs audio in accordance with the output audio signal AOS sent from the analog processing unit 160.
- the input unit 180 is configured by a key unit provided in the main body of the broadcast receiving apparatus 100A or a remote input device including the key unit.
- a key part provided in the main body a touch panel provided in a display unit (not shown) can be used. Moreover, it can replace with the structure which has a key part, and the structure which inputs voice can also be employ
- the input result to the input unit 180 is sent to the control unit 190 as input data IPD.
- the control unit 190 receives the input data IPD sent from the input unit 180. If the content of the input data IPD is channel selection, the control unit 190 generates a channel selection command CSL corresponding to the specified desired station and sends it to the RF processing unit 120. When the content of the input data IPD is a volume adjustment designation, the control unit 190 generates a volume adjustment command VLC corresponding to the designated volume adjustment designation and sends it to the analog processing unit 160.
- the noise detection device 150A includes a Fourier transform unit (FFT unit) 151 as shown in FIG.
- the noise detection device 150 ⁇ / b> A includes a generation unit 152 and a detection unit 153.
- the FFT unit 151 receives the detection signal DTD sent from the detection unit 130. Then, the FFT unit 151 performs Fourier transform on the detection signal DTD. The result (spectrum) of the Fourier transform is sent to the generation unit 152 as the Fourier transform result SP (T) (T: conversion time).
- the generation unit 152 receives the spectrum SP (T) sequentially sent from the FFT unit 151 and the detection presence / absence information NDT sent from the detection unit 153. Then, the generating unit 152 generates a time average spectrum TAS and a threshold curve THC based on a predetermined number of spectra SP (T) that are temporally continuous and the detection presence / absence information NDT. The time average spectrum TAS and the threshold curve THC generated in this way are sent to the detection unit 153.
- the detection unit 153 receives the time average spectrum TAS and the threshold curve THC sent from the generation unit 152. Then, the detection unit 153 detects a subband having an energy value exceeding the threshold curve THC in the time average spectrum TAS as a noise frequency region. The noise frequency domain information thus detected is sent as noise frequency domain information NRI to the reduction unit 156A.
- the detection unit 153 generates detection presence / absence information NDT.
- the detection unit 153 sets the detection presence / absence information NDT to “1” when the noise frequency region is detected.
- the detection unit 153 sets the detection presence / absence information NDT to “0” when the noise frequency region is not detected.
- the detection presence / absence information NDT generated in this way is sent to the generation unit 152.
- the generation unit 152 includes a time averaging unit 211, a frequency averaging unit 212, and an offset processing unit 213.
- the time averaging unit 211 receives the spectrum SP (T) sequentially sent from the FFT unit 151.
- the time averaging unit 211 calculates the time average spectrum TAS of the predetermined number of spectra SP (T) each time a new set of the predetermined number of spectra SP (T) continuous in time is prepared.
- the time-average spectrum TAS calculated in this way is sent to the frequency averaging unit 212 and the detection unit 153.
- the “predetermined number” is determined in advance based on experiments, simulations, experiences, and the like from the viewpoint of detecting an appropriate noise frequency region.
- the frequency averaging unit 212 receives the time average spectrum TAS sent from the time averaging unit 211. Subsequently, the frequency averaging unit 212 averages the time average spectrum TAS along the frequency axis direction to calculate the frequency average spectrum FAS.
- the frequency average spectrum FAS calculated in this way is sent to the offset processing unit 213 as a reference curve indicating an energy value according to a change in frequency.
- the frequency average spectrum FAS is also referred to as “reference curve FAS”.
- a low-pass filter method can be used.
- a low-pass filter an FIR (Finite Impulse Response) filter or an IIR (Infinite Impulse Response) filter may be employed. Further, by detecting a peak before the low-pass filter and omitting the peak, the influence of the reference curve on the peak may be reduced.
- the offset processing unit 213 receives the reference curve FAS sent from the frequency averaging unit 212 and the detection presence / absence information NDT sent from the detection unit 153. And the offset process part 213 performs the offset process according to the value of the detection presence information NDT with respect to the reference curve FAS, and produces
- the threshold curve THC generated in this way is sent to the detection unit 153.
- the channel selection designation has already been input to the input unit 180 by the user, and the channel selection command CSL corresponding to the designated desired station has been sent to the RF processing unit 120. Further, it is assumed that a volume adjustment designation has already been input by the user to the input unit 180, and a volume adjustment command VLC corresponding to the designated volume adjustment mode has been sent to the analog processing unit 160 (FIG. 1). reference).
- the signal RFS is sent from the antenna 110 to the RF processing unit 120. Then, in the RF processing unit 120, after the signal of the desired station to be selected is converted into a signal in the intermediate frequency band, AD conversion is performed.
- the RF processing unit 120 sends the AD conversion result to the detection unit 130 as an intermediate frequency signal IFD (see FIG. 1).
- the detection unit 130 Upon receiving the intermediate frequency signal IFD, the detection unit 130 performs detection processing on the intermediate frequency signal IFD. Then, the detection unit 130 sends the detection result as a detection signal DTD to the noise detection device 150A in the noise reduction device 140A (see FIG. 1).
- the FFT unit 151 receives the detection signal DTD. Subsequently, the FFT unit 151 performs a Fourier transform on the detection signal DTD. Then, the FFT unit 151 sends the spectrum SP (T) that is the result of the Fourier transform to the generation unit 152 (see FIG. 2).
- the voiceband ABD of interest of the Fourier transform by the FFT unit 151 and a frequency resolution F R width subbands SB 1 ⁇ SB N of FFT unit 151.
- the Fourier transform result SP (T) is configured as an energy value for each subband SB j .
- the time averaging unit 211 receives the spectrum SP (T). Subsequently, the time averaging unit 211 calculates the time average spectrum TAS of the predetermined number of spectra SP (T) each time a new set of the predetermined number of spectra SP (T) continuous in time is prepared. Then, the time averaging unit 211 sends the calculated time average spectrum TAS to the frequency averaging unit 212 and the detection unit 153 (see FIG. 3).
- FIG. 5 (B) An example of the time average spectrum TAS calculated when the predetermined number is “5” as shown in FIG. 5 (A) is shown in FIG. 5 (B).
- the frequency averaging unit 212 averages a frequency width wider than the sub-band width along the frequency axis direction with respect to the time average spectrum TAS, and the reference curve FAS. Is calculated. Then, the frequency averaging unit 212 sends the calculated reference curve FAS to the offset processing unit 213.
- the energy value for each subband in the reference curve FAS is referred to as a “reference energy value” for each subband.
- FIG. 6B shows an example of the reference curve FAS calculated from the time average spectrum TAS shown in FIG. 6A, which is a reprint of FIG. 5B.
- the offset processing unit 213 Upon receiving the reference curve FAS, the offset processing unit 213 performs an offset process on the reference curve FAS to generate a threshold curve THC.
- the offset processing unit 213 calculates the sum of reference energy values over the entire voice band. Subsequently, the offset processing unit 213 performs an offset process on the reference curve FAS so that the energy value of the sum is smaller than that when the energy value of the sum is concentrated in the estimated frequency width region of the noise frequency region, and the threshold curve THC. Is generated. Then, the offset processing unit 213 sends the generated threshold curve THC to the detection unit 153 (see FIG. 3).
- the offset processing unit 213 has a hysteresis characteristic for detecting the noise frequency region. For this reason, when the latest detection presence / absence information NDT sent from the detection unit 153 is “0”, the offset processing unit 213 performs the first offset processing. On the other hand, when the latest detection presence / absence information NDT is “1”, the offset processing unit 213 performs first offset processing when the latest detection presence / absence information NDT is “0”. The second offset processing is performed with an offset amount smaller than the offset amount at.
- the estimated frequency width of the noise frequency region is determined in advance based on experiments, simulations, and experiences. Among various energy distributions of beat noise in the noise frequency region, the energy distribution is uniform over the estimated frequency width of the noise frequency region, that is, the energy distribution when the maximum reference energy value in the noise frequency region is minimum. Correspondingly, offset processing is performed.
- ⁇ Processing in Detection Unit 153 Upon receiving the new time average spectrum TAS and threshold curve THC, the detection unit 153 detects a subband having an energy value exceeding the threshold curve THC in the time average spectrum TAS as a noise frequency region. Then, the detection unit 153 sends the detected noise frequency domain information as noise frequency domain information NRI to the reduction unit 156A (see FIG. 2).
- noise frequency region information NRI If no noise frequency region is detected, a message to that effect is sent to the reduction unit 156A as noise frequency region information NRI.
- the detection unit 153 sets the detection presence / absence information NDT to “1”. On the other hand, the detection unit 153 sets the detection presence / absence information NDT to “0” when the noise frequency region is not detected. Then, the detection unit 153 sends detection presence / absence information NDT having a set value to the generation unit 152.
- the reduction unit 156A Upon receiving the noise frequency domain information NRI, the reduction unit 156A sets the internal variable notch filter to reduce the noise frequency domain component indicated by the noise frequency domain information NRI. Under this setting, when receiving the detection signal DTD sent from the detection unit 130, the reduction unit 156A reduces the noise frequency domain component in the detection signal DTD and generates the signal AOD. Then, the reduction unit 156A sends the generated signal AOD to the analog processing unit 160 (see FIG. 1).
- the reduction unit 156A does not perform the reduction process.
- the analog processing unit 160 sequentially performs signal processing by the DA conversion unit, the volume adjustment unit, and the power amplification unit, and generates an output audio signal AOS. Then, the analog processing unit 160 sends the generated output audio signal AOS to the speaker unit 170 (see FIG. 1). As a result, the speaker unit 170 reproduces and outputs sound according to the output sound signal AOS.
- the noise frequency region cannot be detected more frequently as the energy in the region other than the noise frequency region, that is, the energy of the voice component increases. However, erroneous detection in the noise frequency region does not occur.
- the higher the energy of the audio component the higher the degree of masking of beat noise by the audio. For this reason, the higher the energy of the audio component, the harder it is to hear the beat noise sound, and the less likely it is to feel strange. For this reason, when the energy of the audio component is high, no practical problem occurs even if the noise frequency region of the beat noise component cannot be detected.
- the generation unit 152 calculates the time average spectrum TAS by averaging the frequency components of the detection signal DTD, which is an audio signal, for each subband width. Subsequently, the generation unit 152 performs frequency averaging along the frequency axis on the time average spectrum TAS with a frequency width wider than the sub-bandwidth, and calculates a reference curve FAS including reference energy values for each sub-bandwidth. To do.
- the generation unit 152 generates a threshold curve THC based on the reference curve FAS. Then, the detection unit 153 detects a frequency region in the time average spectrum TAS having an energy value exceeding the threshold curve THC as a noise frequency region.
- the noise detection device 150A of the first embodiment even if the energy value of the beat noise component or the energy value of the audio signal changes due to the influence of the surrounding environment, the noise frequency band including the beat noise component is appropriately set. Can be detected.
- the reduction unit 156A reduces the frequency component in the noise frequency region detected by the noise detection device 150A from the detection signal DTD. Therefore, according to the noise reduction device 140A of the first embodiment, even if the energy value of the beat noise component or the energy value of the audio signal changes due to the influence of the surrounding environment, the beat noise component can be appropriately reduced. .
- the generation unit 152 generates the threshold curve THC by performing an offset process on the reference energy value. Therefore, an appropriate threshold curve THC can be generated in accordance with changes in the energy value of the beat noise component and the energy value of the audio signal.
- the offset processing is performed based on the sum of the reference energy values, the total frequency width subjected to time averaging, and the estimated frequency width of the noise frequency region. For this reason, an appropriate threshold curve THC can be reasonably generated.
- the first offset process is performed when the noise frequency region is not detected by the previous detection unit 153, and the noise frequency region is detected by the previous detection unit 153.
- the second offset processing is performed with the second offset amount smaller than the first offset amount in the case of the threshold curve obtained by the first offset processing. For this reason, hysteresis characteristics can be imparted when noise is detected.
- FIG. 7 is a block diagram illustrating a schematic configuration of a broadcast receiving device 100B including the noise reduction device 140B according to the second embodiment of the present invention.
- the broadcast receiving device 100B is a broadcast receiving device for AM audio broadcasting.
- the broadcast receiving device 100B is different from the above-described broadcast receiving device 100A only in that a noise reducing device 140B is provided instead of the noise reducing device 140A.
- the noise reduction device 140B is different from the noise reduction device 140A in that a noise detection device 150B is provided instead of the noise detection device 150A.
- this difference will be mainly described.
- the noise detection device 150B is different from the noise detection device 150A in that it further includes an audio reduction unit 155. Then, the FFT unit 151 receives the audio reduction signal ADD sent from the audio reduction unit 155.
- the voice reduction unit 155 receives the intermediate frequency signal IFD sent from the RF processing unit 120. Then, the audio reduction unit 155 generates the audio reduction signal ADD by reducing the audio signal component without reducing the beat noise component. The sound reduction signal ADD thus generated is sent to the FFT unit 151.
- the sound reduction unit 155 Upon receiving the intermediate frequency signal IFD, the sound reduction unit 155 extracts the carrier wave component in the intermediate frequency signal IFD. Subsequently, the voice reduction unit 155 performs a 90 ° phase shift process on the extracted carrier wave component to generate a quadrature signal.
- the audio reduction unit 155 multiplies the intermediate frequency signal IFD and the quadrature signal to generate a multiplication signal. Then, the voice reduction unit 155 extracts a voice band component in the multiplication signal and generates a voice reduction signal ADD. As a result, the audio reduction signal ADD with the audio signal component reduced is generated without reducing the beat noise component. Then, the audio reduction unit 155 sends the generated audio reduction signal ADD to the FFT unit 151 (see FIG. 8).
- noise frequency domain information NRI detected based on the voice reduction signal ADD is sent from the noise detection device 150B to the reduction unit 156A (see FIG. 8).
- elements other than the noise detection device 150B in the broadcast receiving device 100B operate in the same manner as in the case of the broadcast receiving device 100A described above.
- the audio reduction unit 155 generates the audio reduction signal ADD in which the audio signal component is reduced without reducing the beat noise component. Then, the noise reduction processing in the first embodiment is performed on the voice reduction signal ADD with the beat noise component in the voice reduction signal ADD, and the noise frequency region where the beat noise component exists in the voice reduction signal ADD is detected. . In other words, the noise frequency region is detected in a state where the sound component that becomes an obstacle when detecting the noise frequency region is reduced.
- the noise detection device 150B of the second embodiment when receiving an AM audio broadcast, the noise frequency region can be detected with higher accuracy than in the case of the first embodiment.
- the reduction unit 156A reduces the frequency component of the noise frequency region detected by the noise detection device 150B from the detection signal DTD. Therefore, according to the noise reduction device 140B of the second embodiment, the beat noise component can be appropriately reduced even when the energy value of the beat noise component or the energy value of the audio signal changes when receiving the AM audio broadcast. Can do.
- a third embodiment of the present invention will be described with reference mainly to FIG. 9 and FIG.
- FIG. 9 is a block diagram illustrating a schematic configuration of a broadcast receiving device 100C including the noise reduction device 140C according to the third embodiment of the present invention.
- the broadcast receiving device 100C is different from the above-described broadcast receiving device 100B only in that a noise reducing device 140C is provided instead of the noise reducing device 140B.
- the noise reduction device 140C is different from the noise reduction device 140B in that a reduction unit 156C is provided instead of the reduction unit 156A.
- this difference will be mainly described.
- the above reduction unit 156C includes an FFT unit 231 and a removal unit 232 as shown in FIG. Further, the reduction unit 156C includes an inverse Fourier transform unit (IFFT unit) 233.
- IFFT unit inverse Fourier transform unit
- the FFT unit 231 receives the detection signal DTD sent from the detection unit 130. Then, the FFT unit 231 performs Fourier transform on the detection signal DTD. The result of the Fourier transform is sent to the removal unit 232 as a spectrum SQD.
- the above removal unit 232 receives the spectrum SQD sent from the FFT unit 231 and the noise frequency domain information NRI sent from the noise detection device 150B. Then, the removal unit 232 generates a noise removal spectrum SRD based on the spectrum SQD and the noise frequency domain information NRI. The noise removal spectrum SRD generated in this way is sent to the IFFT unit 233.
- the IFFT unit 233 receives the noise removal spectrum SRD sent from the removal unit 232. Then, the IFFT unit 233 performs an inverse Fourier transform on the noise removal spectrum SRD to generate a signal AOD. The signal AOD generated in this way is sent to the analog processing unit 160.
- the FFT unit 231 Upon receiving the detection signal DTD, the FFT unit 231 performs a Fourier transform on the detection signal DTD to generate a spectrum SQD. Then, the FFT unit 231 sends the generated spectrum SQD to the removal unit 232 (see FIG. 10).
- the removal unit 232 Upon receiving the spectrum SQD, the removal unit 232 generates a noise removal spectrum SRD by removing the component in the noise frequency domain indicated by the latest noise frequency domain information NRI from the spectrum SQD. Then, the removal unit 232 sends the generated noise removal spectrum SRD to the IFFT unit 233.
- the IFFT unit 233 When receiving the noise removal spectrum SRD, the IFFT unit 233 performs inverse Fourier transform on the noise removal spectrum SRD to generate a signal AOD. Then, the IFFT unit 233 sends the generated signal AOD to the analog processing unit 160.
- the reduction unit 156C reduces the frequency component in the noise frequency region detected by the noise detection device 150B from the detection signal DTD. Therefore, according to the noise reduction device 140C of the third embodiment, the beat noise component can be appropriately reduced even if the energy value of the beat noise component or the energy value of the audio signal changes.
- a modification similar to the modification from the second embodiment to the third embodiment may be applied to the first embodiment.
- the frequency width targeted for frequency averaging may be the entire width of the audio band, or a predetermined multiple of the subband width.
- the hysteresis frequency is detected in the noise frequency region.
- the noise frequency region is not detected after the noise frequency region is detected, information on the noise frequency region detected immediately before the noise frequency region is not detected is sent to the reduction unit over a predetermined time. You may do it.
- the threshold curve changes according to the frequency distribution of energy other than the beat noise component. For this reason, even when the high frequency is intentionally attenuated as the reproduction frequency characteristic or the reproduction frequency characteristic is changed according to the electric field strength, the present invention can be applied to detect an appropriate noise frequency region. Good.
- the present invention is applied to noise detection and noise reduction in an audio signal.
- the present invention may be applied to noise detection and noise reduction in a signal other than an audio signal. Good.
- the noise detection device and the reduction unit in the first to third embodiments described above are configured as a computer as a calculation unit including a DSP (Digital Signal Processor) and the like, and a program prepared in advance is executed on the computer. Accordingly, part or all of the processing in the first to third embodiments may be executed.
- This program is recorded on a computer-readable recording medium such as a hard disk, CD-ROM, or DVD, and is read from the recording medium and executed by the computer.
- the program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a form distributed via a network such as the Internet. Also good.
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Noise Elimination (AREA)
Abstract
In the present invention, a generation unit (152) calculates a time average spectrum (TAS) by time averaging the frequency components of a detected signal (DTD), which is an audio signal, for every sub-bandwidth. Then, using a frequency width wider than the sub-bandwidths, the generation unit (152) carries out frequency averaging with respect to the time average spectrum (TAS), such frequency averaging being along the frequency axis, and thereby calculates a reference curve constituted by the reference energy value of each sub-bandwidth. Next, the generation unit (152) generates a threshold curve (THC) on the basis of the reference curve. A detection unit (153) detects, as a noise frequency region, a frequency region in the time average spectrum (TAS) the energy value of which exceeds the threshold curve (THC). As a result, even if the energy value of a beat noise component or the energy value of an audio signal change due to the impact of the surrounding environment, a noise frequency band which includes the beat noise component can be appropriately detected.
Description
本発明は、ノイズ検出装置、ノイズ低減装置、ノイズ検出方法及びノイズ検出プログラム、並びに、当該ノイズ検出プログラムが記録された記録媒体に関する。
The present invention relates to a noise detection device, a noise reduction device, a noise detection method and a noise detection program, and a recording medium on which the noise detection program is recorded.
従来から、音声放送波を受信して処理し、放送音声を出力する放送受信装置が広く普及している。こうした放送受信装置による出力音声に含まれることがあるノイズ音の一つとして、いわゆるビートノイズ音がある。
Conventionally, broadcast receivers that receive and process audio broadcast waves and output broadcast audio have become widespread. One of the noise sounds that may be included in the output sound from such a broadcast receiving apparatus is a so-called beat noise sound.
かかるビートノイズ音の原因となるビートノイズ成分が音声信号の帯域内にあると、音声成分とビートノイズ成分との識別が難しい。固定的に配置された周囲の電子装置等に由来するビートノイズ成分であれば、ビートノイズ成分の周波数を予め調べておき、その周波数成分だけを低減させることによりビートノイズ音を低減させることができる。しかしながら、この方法では、様々な周波数を有するビートノイズ成分が周囲環境から混入してくる場合には、ビートノイズ音を低減させることができなかった。
If the beat noise component that causes such beat noise is within the band of the audio signal, it is difficult to distinguish the audio component from the beat noise component. If it is a beat noise component derived from a fixedly arranged peripheral electronic device or the like, it is possible to reduce the beat noise sound by examining the frequency of the beat noise component in advance and reducing only the frequency component. . However, with this method, when beat noise components having various frequencies are mixed in from the surrounding environment, the beat noise sound cannot be reduced.
そこで、音声信号である検波信号のパワースペクトルを時間平均して得られる時間平均スペクトルに基づいて、検波信号に含まれるビートノイズ成分を検出する技術が提案されている(特許文献1参照:)以下、「従来例」と呼ぶ)。この従来例の技術においては、検波信号の時間平均スペクトルでは、ビートノイズ成分が強調されることを利用している。そして、時間平均スペクトルにおいて所定閾値以上のエネルギー値となる周波数領域を、ノイズ周波数領域として検出するようになっている。
Therefore, a technique for detecting a beat noise component included in a detection signal based on a time-average spectrum obtained by time-averaging a power spectrum of a detection signal that is an audio signal has been proposed (see Patent Document 1). , Called “conventional example”). This prior art technique uses the fact that the beat noise component is emphasized in the time average spectrum of the detection signal. And the frequency area | region which becomes an energy value more than a predetermined threshold in a time average spectrum is detected as a noise frequency area | region.
上述した従来例の技術では、ノイズ周波数領域以外の周波数領域における信号成分のエネルギー値も高い場合、所定閾値が一定であると、ノイズ周波数領域以外の周波数領域をノイズ周波数領域として誤検出してしまう。このため、所定閾値を安易に下げることはできない。
In the conventional technique described above, when the energy value of the signal component in the frequency region other than the noise frequency region is high, if the predetermined threshold is constant, the frequency region other than the noise frequency region is erroneously detected as the noise frequency region. . For this reason, the predetermined threshold cannot be easily lowered.
ところで、ビートノイズ成分が周囲環境から混入してくる場合には、車両とともに移動する放送受信装置の周囲環境の変化によりビートノイズ成分のエネルギー値も変化する。このため、所定閾値を高く設定しておくと、ビートノイズ成分を検出できない事態が発生し得る。
By the way, when the beat noise component is mixed in from the surrounding environment, the energy value of the beat noise component also changes due to the change in the surrounding environment of the broadcast receiving apparatus that moves with the vehicle. For this reason, if the predetermined threshold is set high, a situation in which the beat noise component cannot be detected may occur.
このため、周囲環境の影響でビートノイズ成分のエネルギー値や、音声信号のエネルギー値が変化しても、ビートノイズ成分が含まれるノイズ周波数帯域を適切に検出することができる技術が望まれている。かかる要請に応えることが、本発明が解決すべき課題の一つとして挙げられる。
For this reason, even if the energy value of the beat noise component or the energy value of the audio signal changes due to the influence of the surrounding environment, a technique that can appropriately detect the noise frequency band including the beat noise component is desired. . Meeting this requirement is one of the problems to be solved by the present invention.
請求項1に記載の発明は、入力した信号の周波数成分を第1周波数幅ごとに時間平均した結果に対して、前記第1周波数幅よりも広い第2周波数幅ごとに周波数軸に沿った周波数平均化を行って得た基準エネルギー値に基づき閾値カーブを生成する生成部と;前記時間平均した結果が前記閾値カーブを超えるエネルギー値となっている周波数領域をノイズ周波数領域として検出する検出部と;を備えることを特徴とするノイズ検出装置である。
According to the first aspect of the present invention, a frequency along the frequency axis for each second frequency width wider than the first frequency width is obtained by averaging the frequency components of the input signal for each first frequency width. A generation unit that generates a threshold curve based on a reference energy value obtained by averaging; a detection unit that detects, as a noise frequency region, a frequency region in which the time averaged result is an energy value exceeding the threshold curve; A noise detecting device comprising:
請求項6に記載の発明は、請求項1に記載のノイズ検出装置と;前記ノイズ検出装置に入力した信号における前記ノイズ検出装置により検出されたノイズ周波数領域の成分を低減させる低減部と;を備えるノイズ低減装置である。
The invention according to claim 6 is the noise detection device according to claim 1; and a reduction unit that reduces a noise frequency domain component detected by the noise detection device in a signal input to the noise detection device. A noise reduction device provided.
請求項7に記載の発明は、生成部と、検出部とを備えるノイズ検出装置において使用されるノイズ検出方法であって、前記生成部が、入力した信号の周波数成分を第1周波数幅ごとに時間平均した結果に対して、前記第1周波数幅よりも広い第2周波数幅ごとに周波数軸に沿った周波数平均化を行って得た基準エネルギー値に基づき閾値カーブを生成する生成工程と;前記検出部が、前記時間平均した結果が前記閾値カーブを超えるエネルギー値となっている周波数領域をノイズ周波数領域として検出する検出工程と;を備えることを特徴とするノイズ検出方法である。
The invention according to claim 7 is a noise detection method used in a noise detection apparatus including a generation unit and a detection unit, wherein the generation unit calculates a frequency component of an input signal for each first frequency width. Generating a threshold curve based on a reference energy value obtained by performing frequency averaging along the frequency axis for each second frequency width wider than the first frequency width with respect to the result of time averaging; And a detection step of detecting, as a noise frequency region, a frequency region in which the time averaged result has an energy value exceeding the threshold curve, as a noise detection method.
請求項8に記載の発明は、ノイズ検出装置が有するコンピュータに、請求項7に記載のノイズ検出方法を実行させる、ことを特徴とするノイズ検出プログラムである。
The invention described in claim 8 is a noise detection program characterized by causing a computer included in the noise detection apparatus to execute the noise detection method according to claim 7.
請求項9に記載の発明は、ノイズ検出装置が有するコンピュータにより読み取り可能に、請求項8に記載のノイズ検出プログラムが記録されている、ことを特徴とする記録媒体である。
The invention described in claim 9 is a recording medium in which the noise detection program according to claim 8 is recorded so as to be readable by a computer included in the noise detection device.
140A~140C … ノイズ低減装置
150A,150B … ノイズ検出装置
152 … 生成ユニット(生成部)
153 … 検出ユニット(検出部)
156A,156C … 低減ユニット(低減部) 140A to 140C ... Noise reduction device 150A, 150B ... Noise detection device 152 ... Generation unit (generation unit)
153 ... Detection unit (detection unit)
156A, 156C ... Reduction unit (reduction unit)
150A,150B … ノイズ検出装置
152 … 生成ユニット(生成部)
153 … 検出ユニット(検出部)
156A,156C … 低減ユニット(低減部) 140A to 140C ...
153 ... Detection unit (detection unit)
156A, 156C ... Reduction unit (reduction unit)
以下、本発明の実施形態を、添付図面を参照して説明する。なお、以下の説明及び図面においては、同一又は同等の要素には同一の符号を付し、重複する説明を省略する。
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.
[第1実施形態]
まず、本発明の第1実施形態を、図1~図6を参照して説明する。なお、第1実施形態に係るノイズ低減装置として、放送受信装置が備えるノイズ低減装置を例示して説明する。 [First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS. In addition, the noise reduction apparatus with which a broadcast receiving apparatus is provided is illustrated and demonstrated as a noise reduction apparatus which concerns on 1st Embodiment.
まず、本発明の第1実施形態を、図1~図6を参照して説明する。なお、第1実施形態に係るノイズ低減装置として、放送受信装置が備えるノイズ低減装置を例示して説明する。 [First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS. In addition, the noise reduction apparatus with which a broadcast receiving apparatus is provided is illustrated and demonstrated as a noise reduction apparatus which concerns on 1st Embodiment.
<構成>
図1には、本発明の第1実施形態に係るノイズ低減装置140Aを備える放送受信装置100Aの概略的な構成がブロック図にて示されている。 <Configuration>
FIG. 1 is a block diagram showing a schematic configuration of abroadcast receiving device 100A including a noise reduction device 140A according to the first embodiment of the present invention.
図1には、本発明の第1実施形態に係るノイズ低減装置140Aを備える放送受信装置100Aの概略的な構成がブロック図にて示されている。 <Configuration>
FIG. 1 is a block diagram showing a schematic configuration of a
図1に示されるように、放送受信装置100Aは、ノイズ低減装置140Aに加えて、アンテナ110と、RF処理ユニット120と、検波ユニット130とを備えている。また、放送受信装置100Aは、アナログ処理ユニット160と、スピーカユニット170と、入力ユニット180と、制御ユニット190とを備えている。
As shown in FIG. 1, the broadcast receiving device 100A includes an antenna 110, an RF processing unit 120, and a detection unit 130 in addition to the noise reduction device 140A. The broadcast receiving apparatus 100A includes an analog processing unit 160, a speaker unit 170, an input unit 180, and a control unit 190.
上記のアンテナ110は、放送波を受信する。アンテナ110による受信結果は、信号RFSとして、RF処理ユニット120へ送られる。
The antenna 110 receives a broadcast wave. The reception result by the antenna 110 is sent to the RF processing unit 120 as a signal RFS.
上記のRF処理ユニット120は、制御ユニット190から送られた選局指令CSLに従って、選局すべき希望局の信号を信号RFSから抽出する選局処理を行い、所定の中間周波数帯の成分を有する中間周波信号IFDを生成する。そして、RF処理ユニット120は、生成された中間周波信号IFDを、検波ユニット130へ送る。このRF処理ユニット120は、入力フィルタと、高周波増幅器(RF-AMP:Radio Frequency-Amplifier)と、バンドパスフィルタ(以下、「RFフィルタ」とも呼ぶ)とを備えている。また、RF処理ユニット120は、ミキサ(混合器)と、中間周波フィルタ(以下、「IFフィルタ」とも呼ぶ)と、AD(Analogue to Digital)変換器と、局部発振回路(OSC)とを備えている。
The RF processing unit 120 performs channel selection processing for extracting a signal of a desired station to be selected from the signal RFS in accordance with the channel selection command CSL sent from the control unit 190, and has a component in a predetermined intermediate frequency band. An intermediate frequency signal IFD is generated. Then, the RF processing unit 120 sends the generated intermediate frequency signal IFD to the detection unit 130. The RF processing unit 120 includes an input filter, a high-frequency amplifier (RF-AMP: Radio Frequency-Amplifier), and a band-pass filter (hereinafter also referred to as “RF filter”). The RF processing unit 120 includes a mixer (mixer), an intermediate frequency filter (hereinafter also referred to as “IF filter”), an AD (Analogue to Digital) converter, and a local oscillation circuit (OSC). Yes.
ここで、入力フィルタは、アンテナ110から送られた信号RFSの低周波成分を遮断するハイパスフィルタである。高周波増幅器は、入力フィルタを通過した信号を増幅する。RFフィルタは、高周波増幅器から出力された信号のうち、高周波帯の信号を選択的に通過させる。ミキサは、RFフィルタを通過した信号と、局部発振回路から供給された局部発振信号とを混合する。
Here, the input filter is a high-pass filter that blocks low-frequency components of the signal RFS sent from the antenna 110. The high frequency amplifier amplifies the signal that has passed through the input filter. The RF filter selectively passes a signal in a high frequency band among signals output from the high frequency amplifier. The mixer mixes the signal that has passed through the RF filter and the local oscillation signal supplied from the local oscillation circuit.
IFフィルタは、ミキサから出力された信号のうち、予め定められた中間周波数範囲の信号を選択して通過させる。AD変換器は、IFフィルタを通過した信号をデジタル信号に変換する。この変換結果は、中間周波信号IFDとして、検波ユニット130へ送られる。
The IF filter selects and passes a signal in a predetermined intermediate frequency range among the signals output from the mixer. The AD converter converts the signal that has passed through the IF filter into a digital signal. This conversion result is sent to the detection unit 130 as an intermediate frequency signal IFD.
なお、局部発振回路は、電圧制御等により発振周波数の制御が可能な発振器等を備えて構成される。この局部発振回路は、制御ユニット190から送られた選局指令CSLに従って、選局すべき希望局に対応する周波数の局部発振信号を生成し、ミキサへ供給する。
Note that the local oscillation circuit includes an oscillator that can control the oscillation frequency by voltage control or the like. This local oscillation circuit generates a local oscillation signal having a frequency corresponding to a desired station to be selected in accordance with a channel selection command CSL sent from the control unit 190, and supplies it to the mixer.
上記の検波ユニット130は、RF処理ユニット120から送られた中間周波信号IFDを受ける。そして、検波ユニット130は、中間周波信号IFDに対して検波処理を施し、検波結果を検波信号DTDとして、ノイズ低減装置140Aへ送る。ここで、検波信号DTDは、音声帯域の信号(音声信号)となっている。
The detection unit 130 receives the intermediate frequency signal IFD sent from the RF processing unit 120. Then, the detection unit 130 performs detection processing on the intermediate frequency signal IFD, and sends the detection result to the noise reduction device 140A as a detection signal DTD. Here, the detection signal DTD is an audio band signal (audio signal).
上記のノイズ低減装置140Aは、ノイズ検出装置150Aと、低減ユニット156Aとを備えている。
The noise reduction device 140A includes a noise detection device 150A and a reduction unit 156A.
上記のノイズ検出装置150Aは、検波ユニット130から送られた検波信号DTDを受ける。そして、ノイズ検出装置150Aは、検波信号DTDにおけるビートノイズ成分が含まれる周波数領域であるノイズ周波数領域を検出する。ノイズ検出装置150Aによる検出結果は、ノイズ周波数領域情報NRIとして低減ユニット156Aへ送られる。
The noise detection device 150A receives the detection signal DTD sent from the detection unit 130. Then, the noise detection device 150A detects a noise frequency region that is a frequency region including a beat noise component in the detection signal DTD. The detection result by the noise detection device 150A is sent to the reduction unit 156A as noise frequency domain information NRI.
なお、ノイズ検出装置150Aの構成の詳細については、後述する。
The details of the configuration of the noise detection device 150A will be described later.
上記の低減ユニット156Aは、検波ユニット130から送られた検波信号DTD、及び、ノイズ検出装置150Aから送られたノイズ周波数領域情報NRIを受ける。そして、低減ユニット156Aは、検波信号DTDにおけるノイズ周波数領域情報NRIにより示されたノイズ周波数領域の成分を低減させる。この結果、検波信号DTDにおけるビートノイズ成分が低減される。低減ユニット156Aによるビートノイズ成分の低減結果は、信号AODとして、アナログ処理ユニット160へ送られる。
The reduction unit 156A receives the detection signal DTD sent from the detection unit 130 and the noise frequency domain information NRI sent from the noise detection device 150A. Then, the reduction unit 156A reduces the noise frequency domain component indicated by the noise frequency domain information NRI in the detection signal DTD. As a result, the beat noise component in the detection signal DTD is reduced. The beat noise component reduction result by the reduction unit 156A is sent to the analog processing unit 160 as a signal AOD.
なお、第1実施形態では、低減ユニット156Aは、ノイズ周波数領域情報NRIに応じて、低減領域が変化する可変ノッチフィルタを備えて構成されている。
In the first embodiment, the reduction unit 156A includes a variable notch filter in which the reduction region changes according to the noise frequency region information NRI.
上記のアナログ処理ユニット160は、ノイズ低減装置140Aから送られた信号AODを受ける。そして、アナログ処理ユニット160は、制御ユニット190による制御のもとで、出力音声信号AOSを生成し、生成された出力音声信号AOSをスピーカユニット170へ送る。
The analog processing unit 160 receives the signal AOD sent from the noise reduction device 140A. Then, the analog processing unit 160 generates an output audio signal AOS under the control of the control unit 190, and sends the generated output audio signal AOS to the speaker unit 170.
かかる機能を有するアナログ処理ユニット160は、DA(Digital to Analogue)変換部と、音量調整部と、パワー増幅部とを備えて構成されている。ここで、DA変換部は、ノイズ低減装置140Aから送られた信号AODを受ける。そして、DA変換部は、信号AODをアナログ信号に変換する。DA変換部によるアナログ変換結果は音量調整部へ送られる。
The analog processing unit 160 having such a function includes a DA (Digital-to-Analogue) conversion unit, a volume adjustment unit, and a power amplification unit. Here, the DA conversion unit receives the signal AOD sent from the noise reduction device 140A. The DA conversion unit converts the signal AOD into an analog signal. The analog conversion result by the DA conversion unit is sent to the volume adjustment unit.
音量調整部は、DA変換部から送られたアナログ変換結果の信号を受ける。そして、音量調整部は、制御ユニット190からの音量調整指令VLCに従って、アナログ変換結果の信号に対して音量調整処理を施す。なお、音量調整部は、第1実施形態では、電子ボリューム素子等を備えて構成されている。音量調整部による音量調整結果の信号は、パワー増幅部へ送られる。
The volume adjuster receives the analog conversion result signal sent from the DA converter. Then, the volume adjustment unit performs volume adjustment processing on the signal of the analog conversion result in accordance with the volume adjustment command VLC from the control unit 190. In the first embodiment, the volume adjustment unit is configured to include an electronic volume element or the like. The signal of the volume adjustment result by the volume adjustment unit is sent to the power amplification unit.
パワー増幅部は、音量調整部から送られた音量調整結果の信号を受ける。そして、パワー増幅部は、音量調整結果の信号をパワー増幅する。なお、パワー増幅部は、パワー増幅器を備えている。パワー増幅部による増幅結果である出力音声信号AOSは、スピーカユニット170へ送られる。
The power amplification unit receives the signal of the volume adjustment result sent from the volume adjustment unit. The power amplification unit power-amplifies the signal of the volume adjustment result. The power amplification unit includes a power amplifier. An output audio signal AOS that is an amplification result by the power amplification unit is sent to the speaker unit 170.
上記のスピーカユニット170は、スピーカを備えている。このスピーカユニット170は、アナログ処理ユニット160から送られた出力音声信号AOSに従って、音声を再生出力する。
The speaker unit 170 includes a speaker. The speaker unit 170 reproduces and outputs audio in accordance with the output audio signal AOS sent from the analog processing unit 160.
上記の入力ユニット180は、放送受信装置100Aの本体部に設けられたキー部、あるいはキー部を備えるリモート入力装置等により構成される。ここで、本体部に設けられたキー部としては、不図示の表示ユニットに設けられたタッチパネルを用いることができる。また、キー部を有する構成に代えて、音声入力する構成を採用することもできる。入力ユニット180への入力結果は、入力データIPDとして制御ユニット190へ送られる。
The input unit 180 is configured by a key unit provided in the main body of the broadcast receiving apparatus 100A or a remote input device including the key unit. Here, as a key part provided in the main body, a touch panel provided in a display unit (not shown) can be used. Moreover, it can replace with the structure which has a key part, and the structure which inputs voice can also be employ | adopted. The input result to the input unit 180 is sent to the control unit 190 as input data IPD.
上記の制御ユニット190は、入力ユニット180から送られた入力データIPDを受ける。この入力データIPDの内容が選局指定であった場合には、制御ユニット190は、指定された希望局に対応する選局指令CSLを生成して、RF処理ユニット120へ送る。また、入力データIPDの内容が音量調整指定であった場合には、制御ユニット190は、指定された音量調整指定に対応する音量調整指令VLCを生成して、アナログ処理ユニット160へ送る。
The control unit 190 receives the input data IPD sent from the input unit 180. If the content of the input data IPD is channel selection, the control unit 190 generates a channel selection command CSL corresponding to the specified desired station and sends it to the RF processing unit 120. When the content of the input data IPD is a volume adjustment designation, the control unit 190 generates a volume adjustment command VLC corresponding to the designated volume adjustment designation and sends it to the analog processing unit 160.
《ノイズ検出装置150Aの構成》
次に、上記のノイズ検出装置150Aの構成について説明する。 << Configuration ofNoise Detection Device 150A >>
Next, the configuration of thenoise detection device 150A will be described.
次に、上記のノイズ検出装置150Aの構成について説明する。 << Configuration of
Next, the configuration of the
ノイズ検出装置150Aは、図2に示されるように、フーリエ変換ユニット(FFTユニット)151を備えている。また、ノイズ検出装置150Aは、生成ユニット152と、検出ユニット153とを備えている。
The noise detection device 150A includes a Fourier transform unit (FFT unit) 151 as shown in FIG. The noise detection device 150 </ b> A includes a generation unit 152 and a detection unit 153.
上記のFFTユニット151は、検波ユニット130から送られた検波信号DTDを受ける。そして、FFTユニット151は、検波信号DTDにフーリエ変換を施す。かかるフーリエ変換の結果(スペクトル)は、フーリエ変換結果SP(T)(T:変換時刻)として、生成ユニット152へ送られる。
The FFT unit 151 receives the detection signal DTD sent from the detection unit 130. Then, the FFT unit 151 performs Fourier transform on the detection signal DTD. The result (spectrum) of the Fourier transform is sent to the generation unit 152 as the Fourier transform result SP (T) (T: conversion time).
なお、以下の説明においては、フーリエ変換結果SP(T)を「スペクトルSP(T)」と呼ぶものとする。
In the following description, the Fourier transform result SP (T) is referred to as “spectrum SP (T)”.
上記の生成ユニット152は、FFTユニット151から順次送られたスペクトルSP(T)、及び、検出ユニット153から送られた検出有無情報NDTを受ける。そして、生成ユニット152は、時間的に連続する所定個数のスペクトルSP(T)及び検出有無情報NDTに基づいて、時間平均スペクトルTAS及び閾値カーブTHCを生成する。こうして生成された時間平均スペクトルTAS及び閾値カーブTHCは、検出ユニット153へ送られる。
The generation unit 152 receives the spectrum SP (T) sequentially sent from the FFT unit 151 and the detection presence / absence information NDT sent from the detection unit 153. Then, the generating unit 152 generates a time average spectrum TAS and a threshold curve THC based on a predetermined number of spectra SP (T) that are temporally continuous and the detection presence / absence information NDT. The time average spectrum TAS and the threshold curve THC generated in this way are sent to the detection unit 153.
なお、生成ユニット152の構成及び動作の詳細については、後述する。
Note that details of the configuration and operation of the generation unit 152 will be described later.
上記の検出ユニット153は、生成ユニット152から送られた時間平均スペクトルTAS及び閾値カーブTHCを受ける。そして、検出ユニット153は、時間平均スペクトルTASにおいて閾値カーブTHCを超えるエネルギー値となっているサブバンドをノイズ周波数領域として検出する。こうして検出されたノイズ周波数領域の情報は、ノイズ周波数領域情報NRIとして低減ユニット156Aへ送られる。
The detection unit 153 receives the time average spectrum TAS and the threshold curve THC sent from the generation unit 152. Then, the detection unit 153 detects a subband having an energy value exceeding the threshold curve THC in the time average spectrum TAS as a noise frequency region. The noise frequency domain information thus detected is sent as noise frequency domain information NRI to the reduction unit 156A.
また、検出ユニット153は、検出有無情報NDTを生成する。ここで、検出ユニット153は、ノイズ周波数領域が検出された場合には、検出有無情報NDTを「1」とする。一方、検出ユニット153は、ノイズ周波数領域が検出されなかった場合には、検出有無情報NDTを「0」とする。こうして生成された検出有無情報NDTは、生成ユニット152へ送られる。
Also, the detection unit 153 generates detection presence / absence information NDT. Here, the detection unit 153 sets the detection presence / absence information NDT to “1” when the noise frequency region is detected. On the other hand, the detection unit 153 sets the detection presence / absence information NDT to “0” when the noise frequency region is not detected. The detection presence / absence information NDT generated in this way is sent to the generation unit 152.
(生成ユニット152の構成)
次に、上記の生成ユニット152の構成について説明する。この生成ユニット152は、図3に示されるように、時間平均化部211と、周波数平均化部212と、オフセット処理部213とを備えている。 (Configuration of generation unit 152)
Next, the configuration of thegeneration unit 152 will be described. As illustrated in FIG. 3, the generation unit 152 includes a time averaging unit 211, a frequency averaging unit 212, and an offset processing unit 213.
次に、上記の生成ユニット152の構成について説明する。この生成ユニット152は、図3に示されるように、時間平均化部211と、周波数平均化部212と、オフセット処理部213とを備えている。 (Configuration of generation unit 152)
Next, the configuration of the
上記の時間平均化部211は、FFTユニット151から順次送られたスペクトルSP(T)を受ける。そして、時間平均化部211は、時間的に連続する所定個数のスペクトルSP(T)の新たな組が揃うたびに、当該所定個数のスペクトルSP(T)の時間平均スペクトルTASを算出する。こうして算出された時間平均スペクトルTASは、周波数平均化部212及び検出ユニット153へ送られる。
The time averaging unit 211 receives the spectrum SP (T) sequentially sent from the FFT unit 151. The time averaging unit 211 calculates the time average spectrum TAS of the predetermined number of spectra SP (T) each time a new set of the predetermined number of spectra SP (T) continuous in time is prepared. The time-average spectrum TAS calculated in this way is sent to the frequency averaging unit 212 and the detection unit 153.
なお、「所定個数」は、適切なノイズ周波数領域の検出の観点から、実験、シミュレーション、経験等に基づいて予め定められる。
The “predetermined number” is determined in advance based on experiments, simulations, experiences, and the like from the viewpoint of detecting an appropriate noise frequency region.
上記の周波数平均化部212は、時間平均化部211から送られた時間平均スペクトルTASを受ける。引き続き、周波数平均化部212は、時間平均スペクトルTASに対して周波数軸方向に沿って平均化を行って、周波数平均スペクトルFASを算出する。こうして算出された周波数平均スペクトルFASは、周波数の変化に従ったエネルギー値を示す基準カーブとして、オフセット処理部213へ送られる。以下の説明においては、周波数平均スペクトルFASを、「基準カーブFAS」とも記すものとする。
The frequency averaging unit 212 receives the time average spectrum TAS sent from the time averaging unit 211. Subsequently, the frequency averaging unit 212 averages the time average spectrum TAS along the frequency axis direction to calculate the frequency average spectrum FAS. The frequency average spectrum FAS calculated in this way is sent to the offset processing unit 213 as a reference curve indicating an energy value according to a change in frequency. In the following description, the frequency average spectrum FAS is also referred to as “reference curve FAS”.
なお、基準カーブFASの算出に際しては、ローパスフィルタの手法を用いることができる。かかるローパスフィルタとしては、FIR(Finite Impulse Response)フィルタを採用してもよいし、IIR(Infinite Impulse Response)フィルタを採用してもよい。また、ローパスフィルタの前にピークを検出しそのピークを省くことにより基準カーブがピークの影響を受けることを低減するようにしてもよい。
In calculating the reference curve FAS, a low-pass filter method can be used. As such a low-pass filter, an FIR (Finite Impulse Response) filter or an IIR (Infinite Impulse Response) filter may be employed. Further, by detecting a peak before the low-pass filter and omitting the peak, the influence of the reference curve on the peak may be reduced.
上記のオフセット処理部213は、周波数平均化部212から送られた基準カーブFAS、及び、検出ユニット153から送られた検出有無情報NDTを受ける。そして、オフセット処理部213は、検出有無情報NDTの値に応じたオフセット処理を基準カーブFASに対して施して閾値カーブTHCを生成する。こうして生成された閾値カーブTHCは、検出ユニット153へ送られる。
The offset processing unit 213 receives the reference curve FAS sent from the frequency averaging unit 212 and the detection presence / absence information NDT sent from the detection unit 153. And the offset process part 213 performs the offset process according to the value of the detection presence information NDT with respect to the reference curve FAS, and produces | generates the threshold curve THC. The threshold curve THC generated in this way is sent to the detection unit 153.
なお、オフセット処理部213による処理の詳細については、後述する。
Details of the processing by the offset processing unit 213 will be described later.
<動作>
次に、以上のように構成された放送受信装置100Aの動作について、ノイズ検出装置150Aにおけるノイズ検出処理に主に着目して説明する。 <Operation>
Next, the operation of thebroadcast receiving device 100A configured as described above will be described mainly focusing on the noise detection processing in the noise detection device 150A.
次に、以上のように構成された放送受信装置100Aの動作について、ノイズ検出装置150Aにおけるノイズ検出処理に主に着目して説明する。 <Operation>
Next, the operation of the
前提として、入力ユニット180には既に利用者により選局指定が入力されており、指定された希望局に対応する選局指令CSLが、RF処理ユニット120へ送られているものとする。また、入力ユニット180には既に利用者により音量調整指定が入力されており、指定された音量調整態様に対応する音量調整指令VLCが、アナログ処理ユニット160へ送られているものとする(図1参照)。
As a premise, it is assumed that the channel selection designation has already been input to the input unit 180 by the user, and the channel selection command CSL corresponding to the designated desired station has been sent to the RF processing unit 120. Further, it is assumed that a volume adjustment designation has already been input by the user to the input unit 180, and a volume adjustment command VLC corresponding to the designated volume adjustment mode has been sent to the analog processing unit 160 (FIG. 1). reference).
こうした状態で、アンテナ110で放送波を受信すると、信号RFSが、アンテナ110からRF処理ユニット120へ送られる。そして、RF処理ユニット120において、選局すべき希望局の信号が中間周波数帯の信号に変換された後、AD変換が行われる。RF処理ユニット120は、このAD変換の結果を、中間周波信号IFDとして、検波ユニット130へ送る(図1参照)。
In this state, when a broadcast wave is received by the antenna 110, the signal RFS is sent from the antenna 110 to the RF processing unit 120. Then, in the RF processing unit 120, after the signal of the desired station to be selected is converted into a signal in the intermediate frequency band, AD conversion is performed. The RF processing unit 120 sends the AD conversion result to the detection unit 130 as an intermediate frequency signal IFD (see FIG. 1).
中間周波信号IFDを受けると、検波ユニット130が、中間周波信号IFDに対して検波処理を施す。そして、検波ユニット130は、検波結果を、検波信号DTDとして、ノイズ低減装置140Aにおけるノイズ検出装置150Aへ送る(図1参照)。
Upon receiving the intermediate frequency signal IFD, the detection unit 130 performs detection processing on the intermediate frequency signal IFD. Then, the detection unit 130 sends the detection result as a detection signal DTD to the noise detection device 150A in the noise reduction device 140A (see FIG. 1).
ノイズ検出装置150Aでは、FFTユニット151が検波信号DTDを受ける。引き続き、FFTユニット151は、検波信号DTDにフーリエ変換を施す。そして、FFTユニット151は、フーリエ変換の結果であるスペクトルSP(T)を生成ユニット152へ送る(図2参照)。
In the noise detection device 150A, the FFT unit 151 receives the detection signal DTD. Subsequently, the FFT unit 151 performs a Fourier transform on the detection signal DTD. Then, the FFT unit 151 sends the spectrum SP (T) that is the result of the Fourier transform to the generation unit 152 (see FIG. 2).
ここで、フーリエ変換結果SP(T)におけるサブバンドSBj(j=1~N)について、図4を参照して説明する。この図4に示されるように、FFTユニット151によるフーリエ変換の対象となる音声帯域ABDは、FFTユニット151の周波数分解能FRの幅のサブバンドSB1~SBNから構成されている。そして、フーリエ変換結果SP(T)は、サブバンドSBjごとのエネルギー値として構成されるようになっている。
Here, the subband SB j (j = 1 to N) in the Fourier transform result SP (T) will be described with reference to FIG. As shown in this Figure 4, the voiceband ABD of interest of the Fourier transform by the FFT unit 151, and a frequency resolution F R width subbands SB 1 ~ SB N of FFT unit 151. The Fourier transform result SP (T) is configured as an energy value for each subband SB j .
《生成ユニット152における処理》
生成ユニット152では、時間平均化部211がスペクトルSP(T)を受ける。引き続き、時間平均化部211は、時間的に連続する所定個数のスペクトルSP(T)の新たな組が揃うたびに、当該所定個数のスペクトルSP(T)の時間平均スペクトルTASを算出する。そして、時間平均化部211は、算出された時間平均スペクトルTASを、周波数平均化部212及び検出ユニット153へ送る(図3参照)。 << Processing inGeneration Unit 152 >>
In thegeneration unit 152, the time averaging unit 211 receives the spectrum SP (T). Subsequently, the time averaging unit 211 calculates the time average spectrum TAS of the predetermined number of spectra SP (T) each time a new set of the predetermined number of spectra SP (T) continuous in time is prepared. Then, the time averaging unit 211 sends the calculated time average spectrum TAS to the frequency averaging unit 212 and the detection unit 153 (see FIG. 3).
生成ユニット152では、時間平均化部211がスペクトルSP(T)を受ける。引き続き、時間平均化部211は、時間的に連続する所定個数のスペクトルSP(T)の新たな組が揃うたびに、当該所定個数のスペクトルSP(T)の時間平均スペクトルTASを算出する。そして、時間平均化部211は、算出された時間平均スペクトルTASを、周波数平均化部212及び検出ユニット153へ送る(図3参照)。 << Processing in
In the
なお、図5(A)に示されるように所定個数を「5」とした場合に算出される時間平均スペクトルTASの例が、図5(B)に示されている。
An example of the time average spectrum TAS calculated when the predetermined number is “5” as shown in FIG. 5 (A) is shown in FIG. 5 (B).
新たな時間平均スペクトルTASを受けると、周波数平均化部212は、時間平均スペクトルTASに対して、周波数軸方向に沿って、サブバンド幅よりも広い周波数幅の平均化を行って、基準カーブFASを算出する。そして、周波数平均化部212は、算出された基準カーブFASをオフセット処理部213へ送る。以下の説明においては、基準カーブFASにおけるサブバンドごとのエネルギー値を、サブバンドごとの「基準エネルギー値」と呼ぶものとする。
When the new time average spectrum TAS is received, the frequency averaging unit 212 averages a frequency width wider than the sub-band width along the frequency axis direction with respect to the time average spectrum TAS, and the reference curve FAS. Is calculated. Then, the frequency averaging unit 212 sends the calculated reference curve FAS to the offset processing unit 213. In the following description, the energy value for each subband in the reference curve FAS is referred to as a “reference energy value” for each subband.
なお、図5(B)を再掲する図6(A)に示される時間平均スペクトルTASから算出された基準カーブFASの例が、図6(B)に示されている。
FIG. 6B shows an example of the reference curve FAS calculated from the time average spectrum TAS shown in FIG. 6A, which is a reprint of FIG. 5B.
基準カーブFASを受けると、オフセット処理部213は、基準カーブFASに対してオフセット処理を施して閾値カーブTHCを生成する。かかる閾値カーブTHCの生成に際して、第1実施形態では、オフセット処理部213が、音声帯域全域にわたる基準エネルギー値の総和を算出する。引き続き、オフセット処理部213が、当該総和のエネルギー値がノイズ周波数領域の推定周波数幅の領域に集中したとした場合よりも小さなエネルギー値となるオフセット処理を基準カーブFASに対して施し、閾値カーブTHCを生成する。そして、オフセット処理部213は、生成された閾値カーブTHCを検出ユニット153へ送る(図3参照)。
Upon receiving the reference curve FAS, the offset processing unit 213 performs an offset process on the reference curve FAS to generate a threshold curve THC. In generating the threshold curve THC, in the first embodiment, the offset processing unit 213 calculates the sum of reference energy values over the entire voice band. Subsequently, the offset processing unit 213 performs an offset process on the reference curve FAS so that the energy value of the sum is smaller than that when the energy value of the sum is concentrated in the estimated frequency width region of the noise frequency region, and the threshold curve THC. Is generated. Then, the offset processing unit 213 sends the generated threshold curve THC to the detection unit 153 (see FIG. 3).
かかるオフセット処理に際して、第1実施形態では、オフセット処理部213が、ノイズ周波数領域の検出にヒステリシス特性を持たせるようにしている。このため、検出ユニット153から最新で送られた検出有無情報NDTが「0」である場合には、オフセット処理部213は、第1オフセット処理を行う。一方、最新で送られた検出有無情報NDTが「1」である場合には、オフセット処理部213は、当該最新で送られた検出有無情報NDTが「0」であった場合の第1オフセット処理におけるオフセット量よりも小さなオフセット量による第2オフセット処理を行うようになっている。
In such an offset process, in the first embodiment, the offset processing unit 213 has a hysteresis characteristic for detecting the noise frequency region. For this reason, when the latest detection presence / absence information NDT sent from the detection unit 153 is “0”, the offset processing unit 213 performs the first offset processing. On the other hand, when the latest detection presence / absence information NDT is “1”, the offset processing unit 213 performs first offset processing when the latest detection presence / absence information NDT is “0”. The second offset processing is performed with an offset amount smaller than the offset amount at.
第1実施形態では、ノイズ周波数領域の推定周波数幅を、実験、シミュレーション、経験に基づいて予め定めるようになっている。そして、ノイズ周波数領域におけるビートノイズの様々なエネルギー分布のうちで、当該ノイズ周波数領域の推定周波数幅にわたって均一なエネルギー分布、すなわち、ノイズ周波数領域における最大基準エネルギー値が最小となる場合におけるエネルギー分布に対応して、オフセット処理を行うようになっている。
In the first embodiment, the estimated frequency width of the noise frequency region is determined in advance based on experiments, simulations, and experiences. Among various energy distributions of beat noise in the noise frequency region, the energy distribution is uniform over the estimated frequency width of the noise frequency region, that is, the energy distribution when the maximum reference energy value in the noise frequency region is minimum. Correspondingly, offset processing is performed.
なお、生成された閾値カーブTHCの例が、図6(C)に示されている。
Note that an example of the generated threshold curve THC is shown in FIG.
《検出ユニット153における処理》
新たな時間平均スペクトルTAS及び閾値カーブTHCを受けると、検出ユニット153は、時間平均スペクトルTASにおいて閾値カーブTHCを超えるエネルギー値となっているサブバンドをノイズ周波数領域として検出する。そして、検出ユニット153は、検出されたノイズ周波数領域の情報を、ノイズ周波数領域情報NRIとして低減ユニット156Aへ送る(図2参照)。 << Processing inDetection Unit 153 >>
Upon receiving the new time average spectrum TAS and threshold curve THC, thedetection unit 153 detects a subband having an energy value exceeding the threshold curve THC in the time average spectrum TAS as a noise frequency region. Then, the detection unit 153 sends the detected noise frequency domain information as noise frequency domain information NRI to the reduction unit 156A (see FIG. 2).
新たな時間平均スペクトルTAS及び閾値カーブTHCを受けると、検出ユニット153は、時間平均スペクトルTASにおいて閾値カーブTHCを超えるエネルギー値となっているサブバンドをノイズ周波数領域として検出する。そして、検出ユニット153は、検出されたノイズ周波数領域の情報を、ノイズ周波数領域情報NRIとして低減ユニット156Aへ送る(図2参照)。 << Processing in
Upon receiving the new time average spectrum TAS and threshold curve THC, the
なお、ノイズ周波数領域が検出されなかった場合には、その旨が、ノイズ周波数領域情報NRIとして低減ユニット156Aへ送られる。
If no noise frequency region is detected, a message to that effect is sent to the reduction unit 156A as noise frequency region information NRI.
また、検出ユニット153は、ノイズ周波数領域が検出された場合には、検出有無情報NDTを「1」に設定する。一方、検出ユニット153は、ノイズ周波数領域が検出されなかった場合には、検出有無情報NDTを「0」に設定する。そして、検出ユニット153は、設定された値を有する検出有無情報NDTを生成ユニット152へ送る。
Further, when the noise frequency region is detected, the detection unit 153 sets the detection presence / absence information NDT to “1”. On the other hand, the detection unit 153 sets the detection presence / absence information NDT to “0” when the noise frequency region is not detected. Then, the detection unit 153 sends detection presence / absence information NDT having a set value to the generation unit 152.
《低減ユニット156Aによる処理》
ノイズ周波数領域情報NRIを受けると、低減ユニット156Aは、内部の可変ノッチフィルタを、ノイズ周波数領域情報NRIで示されるノイズ周波数領域の成分を低減させるように設定する。かかる設定のもとで、検波ユニット130から送られた検波信号DTDを受けると、低減ユニット156Aは、検波信号DTDにおけるノイズ周波数領域の成分を低減させて、信号AODを生成する。そして、低減ユニット156Aは、生成された信号AODをアナログ処理ユニット160へ送る(図1参照)。 << Processing by thereduction unit 156A >>
Upon receiving the noise frequency domain information NRI, thereduction unit 156A sets the internal variable notch filter to reduce the noise frequency domain component indicated by the noise frequency domain information NRI. Under this setting, when receiving the detection signal DTD sent from the detection unit 130, the reduction unit 156A reduces the noise frequency domain component in the detection signal DTD and generates the signal AOD. Then, the reduction unit 156A sends the generated signal AOD to the analog processing unit 160 (see FIG. 1).
ノイズ周波数領域情報NRIを受けると、低減ユニット156Aは、内部の可変ノッチフィルタを、ノイズ周波数領域情報NRIで示されるノイズ周波数領域の成分を低減させるように設定する。かかる設定のもとで、検波ユニット130から送られた検波信号DTDを受けると、低減ユニット156Aは、検波信号DTDにおけるノイズ周波数領域の成分を低減させて、信号AODを生成する。そして、低減ユニット156Aは、生成された信号AODをアナログ処理ユニット160へ送る(図1参照)。 << Processing by the
Upon receiving the noise frequency domain information NRI, the
なお、ノイズ周波数領域情報NRIが「ノイズ周波数領域が検出されなかった」旨を示している場合には、低減ユニット156Aは、低減処理を行わないようになっている。
When the noise frequency domain information NRI indicates that “the noise frequency domain has not been detected”, the reduction unit 156A does not perform the reduction process.
ノイズ低減装置140Aから送られた信号AODを受けると、アナログ処理ユニット160では、DA変換部、音量調整部及びパワー増幅部による信号処理が順次施され、出力音声信号AOSが生成される。そして、アナログ処理ユニット160は、生成された出力音声信号AOSをスピーカユニット170へ送る(図1参照)。この結果、スピーカユニット170が、出力音声信号AOSに従って、音声を再生出力する。
When the signal AOD sent from the noise reduction device 140A is received, the analog processing unit 160 sequentially performs signal processing by the DA conversion unit, the volume adjustment unit, and the power amplification unit, and generates an output audio signal AOS. Then, the analog processing unit 160 sends the generated output audio signal AOS to the speaker unit 170 (see FIG. 1). As a result, the speaker unit 170 reproduces and outputs sound according to the output sound signal AOS.
なお、上記のように行われるノイズ検出では、ノイズ周波数領域以外の領域におけるエネルギー、すなわち、音声成分のエネルギーが高くなるほど、ノイズ周波数領域の検出ができなくなる場合が多くなる。しかしながら、ノイズ周波数領域の誤検出は発生しない。
In the noise detection performed as described above, the noise frequency region cannot be detected more frequently as the energy in the region other than the noise frequency region, that is, the energy of the voice component increases. However, erroneous detection in the noise frequency region does not occur.
また、音声成分のエネルギーが高くなるほど、音声によるビートノイズのマスキングの度合いが高まる。このため、音声成分のエネルギーが高くなるほど、ビートノイズ音が聞こえづらくなり、聴感上の違和感が発生しにくくなる。このため、音声成分のエネルギーが高い場合には、ビートノイズ成分のノイズ周波数領域が検出できなくとも実用上の問題は発生しない。
Also, the higher the energy of the audio component, the higher the degree of masking of beat noise by the audio. For this reason, the higher the energy of the audio component, the harder it is to hear the beat noise sound, and the less likely it is to feel strange. For this reason, when the energy of the audio component is high, no practical problem occurs even if the noise frequency region of the beat noise component cannot be detected.
以上説明したように、第1実施形態では、生成ユニット152が、音声信号である検波信号DTDの周波数成分をサブバンド幅ごとに時間平均して時間平均スペクトルTASを算出する。引き続き、生成ユニット152が、サブバンド幅よりも広い周波数幅で時間平均スペクトルTASに対して周波数軸に沿った周波数平均化を行って、サブバンド幅ごとの基準エネルギー値からなる基準カーブFASを算出する。
As described above, in the first embodiment, the generation unit 152 calculates the time average spectrum TAS by averaging the frequency components of the detection signal DTD, which is an audio signal, for each subband width. Subsequently, the generation unit 152 performs frequency averaging along the frequency axis on the time average spectrum TAS with a frequency width wider than the sub-bandwidth, and calculates a reference curve FAS including reference energy values for each sub-bandwidth. To do.
次に、生成ユニット152が、基準カーブFASに基づいて閾値カーブTHCを生成する。そして、検出ユニット153が、閾値カーブTHCを超えるエネルギー値となっている時間平均スペクトルTASにおける周波数領域をノイズ周波数領域として検出する。
Next, the generation unit 152 generates a threshold curve THC based on the reference curve FAS. Then, the detection unit 153 detects a frequency region in the time average spectrum TAS having an energy value exceeding the threshold curve THC as a noise frequency region.
したがって、第1実施形態のノイズ検出装置150Aによれば、周囲環境の影響でビートノイズ成分のエネルギー値や、音声信号のエネルギー値が変化しても、ビートノイズ成分が含まれるノイズ周波数帯域を適切に検出することができる。
Therefore, according to the noise detection device 150A of the first embodiment, even if the energy value of the beat noise component or the energy value of the audio signal changes due to the influence of the surrounding environment, the noise frequency band including the beat noise component is appropriately set. Can be detected.
また、第1実施形態では、低減ユニット156Aが、ノイズ検出装置150Aにより検出されたノイズ周波数領域の周波数成分を、検波信号DTDから低減させる。したがって、第1実施形態のノイズ低減装置140Aによれば、周囲環境の影響でビートノイズ成分のエネルギー値や、音声信号のエネルギー値が変化しても、ビートノイズ成分を適切に低減させることができる。
In the first embodiment, the reduction unit 156A reduces the frequency component in the noise frequency region detected by the noise detection device 150A from the detection signal DTD. Therefore, according to the noise reduction device 140A of the first embodiment, even if the energy value of the beat noise component or the energy value of the audio signal changes due to the influence of the surrounding environment, the beat noise component can be appropriately reduced. .
また、第1実施形態では、生成ユニット152が、基準エネルギー値に対してオフセット処理を施すことにより、閾値カーブTHCを生成する。このため、ビートノイズ成分のエネルギー値や、音声信号のエネルギー値が変化に応じて、適切な閾値カーブTHCを生成することができる。
In the first embodiment, the generation unit 152 generates the threshold curve THC by performing an offset process on the reference energy value. Therefore, an appropriate threshold curve THC can be generated in accordance with changes in the energy value of the beat noise component and the energy value of the audio signal.
また、第1実施形態では、オフセット処理が、基準エネルギー値の総和、時間平均の対象となった全周波数幅及びノイズ周波数領域の推定周波数幅に基づいて行われる。このため、適切な閾値カーブTHCを合理的に生成することができる。
Further, in the first embodiment, the offset processing is performed based on the sum of the reference energy values, the total frequency width subjected to time averaging, and the estimated frequency width of the noise frequency region. For this reason, an appropriate threshold curve THC can be reasonably generated.
また、第1実施形態では、前回の検出ユニット153による検出によりノイズ周波数領域が検出されなかった場合に第1オフセット処理が行われ、前回の検出ユニット153による検出によりノイズ周波数領域が検出された場合に、第1オフセット処理により得られる閾値カーブの場合の第1オフセット量よりも小さな第2オフセット量による第2オフセット処理が行われる。このため、ノイズ検出に際して、ヒステリシス特性を付与することができる。
In the first embodiment, the first offset process is performed when the noise frequency region is not detected by the previous detection unit 153, and the noise frequency region is detected by the previous detection unit 153. In addition, the second offset processing is performed with the second offset amount smaller than the first offset amount in the case of the threshold curve obtained by the first offset processing. For this reason, hysteresis characteristics can be imparted when noise is detected.
[第2実施形態]
次に、本発明の第2実施形態を、図7及び図8を主に参照して説明する。 [Second Embodiment]
Next, a second embodiment of the present invention will be described with reference mainly to FIGS.
次に、本発明の第2実施形態を、図7及び図8を主に参照して説明する。 [Second Embodiment]
Next, a second embodiment of the present invention will be described with reference mainly to FIGS.
<構成>
図7には、本発明の第2実施形態に係るノイズ低減装置140Bを備える放送受信装置100Bの概略的な構成がブロック図にて示されている。なお、放送受信装置100Bは、AM音声放送の放送受信装置となっている。 <Configuration>
FIG. 7 is a block diagram illustrating a schematic configuration of abroadcast receiving device 100B including the noise reduction device 140B according to the second embodiment of the present invention. The broadcast receiving device 100B is a broadcast receiving device for AM audio broadcasting.
図7には、本発明の第2実施形態に係るノイズ低減装置140Bを備える放送受信装置100Bの概略的な構成がブロック図にて示されている。なお、放送受信装置100Bは、AM音声放送の放送受信装置となっている。 <Configuration>
FIG. 7 is a block diagram illustrating a schematic configuration of a
図7に示されるように、放送受信装置100Bは、上述した放送受信装置100Aと比べて、ノイズ低減装置140Aに代えてノイズ低減装置140Bを備える点のみが異なっている。そして、ノイズ低減装置140Bは、ノイズ低減装置140Aと比べて、ノイズ検出装置150Aに代えてノイズ検出装置150Bを備えている点が異なっている。以下、この相違点に主に着目して説明する。
As shown in FIG. 7, the broadcast receiving device 100B is different from the above-described broadcast receiving device 100A only in that a noise reducing device 140B is provided instead of the noise reducing device 140A. The noise reduction device 140B is different from the noise reduction device 140A in that a noise detection device 150B is provided instead of the noise detection device 150A. Hereinafter, this difference will be mainly described.
上記のノイズ検出装置150Bは、図8に示されるように、ノイズ検出装置150Aと比べて、音声低減ユニット155を更に備える点が異なっている。そして、FFTユニット151が、音声低減ユニット155から送られた音声低減信号ADDを受けるようになっている。
As shown in FIG. 8, the noise detection device 150B is different from the noise detection device 150A in that it further includes an audio reduction unit 155. Then, the FFT unit 151 receives the audio reduction signal ADD sent from the audio reduction unit 155.
上記の音声低減ユニット155は、RF処理ユニット120から送られた中間周波信号IFDを受ける。そして、音声低減ユニット155は、ビートノイズ成分を低減させることなく、音声信号成分を低減させて、音声低減信号ADDを生成する。こうして生成された音声低減信号ADDは、FFTユニット151へ送られる。
The voice reduction unit 155 receives the intermediate frequency signal IFD sent from the RF processing unit 120. Then, the audio reduction unit 155 generates the audio reduction signal ADD by reducing the audio signal component without reducing the beat noise component. The sound reduction signal ADD thus generated is sent to the FFT unit 151.
なお、音声低減ユニット155による処理の詳細については、後述する。
Note that details of the processing by the audio reduction unit 155 will be described later.
<動作>
次に、以上のように構成された放送受信装置100Bの動作について、ノイズ検出装置150Bにおけるノイズ検出処理に着目して説明する。 <Operation>
Next, the operation of thebroadcast receiving device 100B configured as described above will be described by focusing on the noise detection processing in the noise detection device 150B.
次に、以上のように構成された放送受信装置100Bの動作について、ノイズ検出装置150Bにおけるノイズ検出処理に着目して説明する。 <Operation>
Next, the operation of the
中間周波信号IFDを受けると、音声低減ユニット155は、中間周波信号IFDにおける搬送波成分を抽出する。引き続き、音声低減ユニット155は、抽出された搬送波成分に対して90°移相処理を施して直交信号を生成する。
Upon receiving the intermediate frequency signal IFD, the sound reduction unit 155 extracts the carrier wave component in the intermediate frequency signal IFD. Subsequently, the voice reduction unit 155 performs a 90 ° phase shift process on the extracted carrier wave component to generate a quadrature signal.
次に、音声低減ユニット155は、中間周波信号IFDと直交信号とを乗算し、乗算信号を生成する。そして、音声低減ユニット155は、乗算信号における音声帯域の成分を抽出して、音声低減信号ADDを生成する。この結果、ビートノイズ成分を低減させることなく、音声信号成分を低減させた音声低減信号ADDが生成される。そして、音声低減ユニット155は、生成された音声低減信号ADDをFFTユニット151へ送る(図8参照)。
Next, the audio reduction unit 155 multiplies the intermediate frequency signal IFD and the quadrature signal to generate a multiplication signal. Then, the voice reduction unit 155 extracts a voice band component in the multiplication signal and generates a voice reduction signal ADD. As a result, the audio reduction signal ADD with the audio signal component reduced is generated without reducing the beat noise component. Then, the audio reduction unit 155 sends the generated audio reduction signal ADD to the FFT unit 151 (see FIG. 8).
以後、FFTユニット151、生成ユニット152及び検出ユニット153が、ノイズ検出装置150Aの場合と同様に動作する。この結果、ノイズ検出装置150Bからは、音声低減信号ADDに基づいて検出されたノイズ周波数領域情報NRIが低減ユニット156Aへ送られる(図8参照)。
Thereafter, the FFT unit 151, the generation unit 152, and the detection unit 153 operate in the same manner as in the case of the noise detection device 150A. As a result, noise frequency domain information NRI detected based on the voice reduction signal ADD is sent from the noise detection device 150B to the reduction unit 156A (see FIG. 8).
なお、放送受信装置100Bにおけるノイズ検出装置150B以外の要素は、上述した放送受信装置100Aの場合と同様に動作する。
In addition, elements other than the noise detection device 150B in the broadcast receiving device 100B operate in the same manner as in the case of the broadcast receiving device 100A described above.
以上説明したように、第2実施形態では、音声低減ユニット155が、ビートノイズ成分を低減させることなく、音声信号成分を低減させた音声低減信号ADDを生成する。そして、音声低減信号ADDにおけるビートノイズ成分を、第1実施形態の場合のノイズ検出処理を音声低減信号ADDに対して施して、音声低減信号ADDにおいてビートノイズ成分が存在するノイズ周波数領域を検出する。すなわち、ノイズ周波数領域の検出に際して邪魔になる音声成分が低減された状態で、ノイズ周波数領域を検出する。
As described above, in the second embodiment, the audio reduction unit 155 generates the audio reduction signal ADD in which the audio signal component is reduced without reducing the beat noise component. Then, the noise reduction processing in the first embodiment is performed on the voice reduction signal ADD with the beat noise component in the voice reduction signal ADD, and the noise frequency region where the beat noise component exists in the voice reduction signal ADD is detected. . In other words, the noise frequency region is detected in a state where the sound component that becomes an obstacle when detecting the noise frequency region is reduced.
したがって、第2実施形態のノイズ検出装置150Bによれば、AM音声放送の受信に際して、第1実施形態の場合よりも精度良くノイズ周波数領域を検出することができる。
Therefore, according to the noise detection device 150B of the second embodiment, when receiving an AM audio broadcast, the noise frequency region can be detected with higher accuracy than in the case of the first embodiment.
また、第2実施形態では、第1実施形態の場合と同様に、低減ユニット156Aが、ノイズ検出装置150Bにより検出されたノイズ周波数領域の周波数成分を、検波信号DTDから低減させる。したがって、第2実施形態のノイズ低減装置140Bによれば、AM音声放送の受信に際して、ビートノイズ成分のエネルギー値や、音声信号のエネルギー値が変化しても、ビートノイズ成分を適切に低減させることができる。
[第3実施形態]
次に、本発明の第3実施形態を、図9及び図10を主に参照して説明する。 In the second embodiment, as in the case of the first embodiment, thereduction unit 156A reduces the frequency component of the noise frequency region detected by the noise detection device 150B from the detection signal DTD. Therefore, according to the noise reduction device 140B of the second embodiment, the beat noise component can be appropriately reduced even when the energy value of the beat noise component or the energy value of the audio signal changes when receiving the AM audio broadcast. Can do.
[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference mainly to FIG. 9 and FIG.
[第3実施形態]
次に、本発明の第3実施形態を、図9及び図10を主に参照して説明する。 In the second embodiment, as in the case of the first embodiment, the
[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference mainly to FIG. 9 and FIG.
<構成>
図9には、本発明の第3実施形態に係るノイズ低減装置140Cを備える放送受信装置100Cの概略的な構成がブロック図にて示されている。 <Configuration>
FIG. 9 is a block diagram illustrating a schematic configuration of abroadcast receiving device 100C including the noise reduction device 140C according to the third embodiment of the present invention.
図9には、本発明の第3実施形態に係るノイズ低減装置140Cを備える放送受信装置100Cの概略的な構成がブロック図にて示されている。 <Configuration>
FIG. 9 is a block diagram illustrating a schematic configuration of a
図9に示されるように、放送受信装置100Cは、上述した放送受信装置100Bと比べて、ノイズ低減装置140Bに代えてノイズ低減装置140Cを備える点のみが異なっている。そして、ノイズ低減装置140Cは、ノイズ低減装置140Bと比べて、低減ユニット156Aに代えて低減ユニット156Cを備えている点が異なっている。以下、この相違点に主に着目して説明する。
As shown in FIG. 9, the broadcast receiving device 100C is different from the above-described broadcast receiving device 100B only in that a noise reducing device 140C is provided instead of the noise reducing device 140B. The noise reduction device 140C is different from the noise reduction device 140B in that a reduction unit 156C is provided instead of the reduction unit 156A. Hereinafter, this difference will be mainly described.
上記の低減ユニット156Cは、図10に示されるように、FFTユニット231と、除去ユニット232とを備えている。また、低減ユニット156Cは、逆フーリエ変換ユニット(IFFTユニット)233を備えている。
The above reduction unit 156C includes an FFT unit 231 and a removal unit 232 as shown in FIG. Further, the reduction unit 156C includes an inverse Fourier transform unit (IFFT unit) 233.
上記のFFTユニット231は、検波ユニット130から送られた検波信号DTDを受ける。そして、FFTユニット231は、検波信号DTDにフーリエ変換を施す。かかるフーリエ変換の結果は、スペクトルSQDとして、除去ユニット232へ送られる。
The FFT unit 231 receives the detection signal DTD sent from the detection unit 130. Then, the FFT unit 231 performs Fourier transform on the detection signal DTD. The result of the Fourier transform is sent to the removal unit 232 as a spectrum SQD.
上記の除去ユニット232は、FFTユニット231から送られたスペクトルSQD、及び、ノイズ検出装置150Bから送られたノイズ周波数領域情報NRIを受ける。そして、除去ユニット232は、スペクトルSQD及びノイズ周波数領域情報NRIに基づいて、ノイズ除去スペクトルSRDを生成する。こうして生成されたノイズ除去スペクトルSRDは、IFFTユニット233へ送られる。
The above removal unit 232 receives the spectrum SQD sent from the FFT unit 231 and the noise frequency domain information NRI sent from the noise detection device 150B. Then, the removal unit 232 generates a noise removal spectrum SRD based on the spectrum SQD and the noise frequency domain information NRI. The noise removal spectrum SRD generated in this way is sent to the IFFT unit 233.
なお、除去ユニット232による処理の詳細については、後述する。
Details of processing by the removal unit 232 will be described later.
上記のIFFTユニット233は、除去ユニット232から送られたノイズ除去スペクトルSRDを受ける。そして、IFFTユニット233は、ノイズ除去スペクトルSRDに逆フーリエ変換を施して、信号AODを生成する。こうして生成された信号AODは、アナログ処理ユニット160へ送られる。
The IFFT unit 233 receives the noise removal spectrum SRD sent from the removal unit 232. Then, the IFFT unit 233 performs an inverse Fourier transform on the noise removal spectrum SRD to generate a signal AOD. The signal AOD generated in this way is sent to the analog processing unit 160.
<動作>
次に、以上のように構成された放送受信装置100Cの動作について、低減ユニット156Cにおけるノイズ低減処理に着目して説明する。 <Operation>
Next, the operation of thebroadcast receiving device 100C configured as described above will be described by focusing on the noise reduction processing in the reduction unit 156C.
次に、以上のように構成された放送受信装置100Cの動作について、低減ユニット156Cにおけるノイズ低減処理に着目して説明する。 <Operation>
Next, the operation of the
検波信号DTDを受けると、FFTユニット231は、検波信号DTDにフーリエ変換を施して、スペクトルSQDを生成する。そして、FFTユニット231は、生成されたスペクトルSQDを除去ユニット232へ送る(図10参照)。
Upon receiving the detection signal DTD, the FFT unit 231 performs a Fourier transform on the detection signal DTD to generate a spectrum SQD. Then, the FFT unit 231 sends the generated spectrum SQD to the removal unit 232 (see FIG. 10).
スペクトルSQDを受けると、除去ユニット232は、最新のノイズ周波数領域情報NRIにより示されるノイズ周波数領域における成分をスペクトルSQDから除去することにより、ノイズ除去スペクトルSRDを生成する。そして、除去ユニット232は、生成されたノイズ除去スペクトルSRDをIFFTユニット233へ送る。
Upon receiving the spectrum SQD, the removal unit 232 generates a noise removal spectrum SRD by removing the component in the noise frequency domain indicated by the latest noise frequency domain information NRI from the spectrum SQD. Then, the removal unit 232 sends the generated noise removal spectrum SRD to the IFFT unit 233.
ノイズ除去スペクトルSRDを受けると、IFFTユニット233は、ノイズ除去スペクトルSRDに逆フーリエ変換を施して、信号AODを生成する。そして、IFFTユニット233は、生成された信号AODをアナログ処理ユニット160へ送る。
When receiving the noise removal spectrum SRD, the IFFT unit 233 performs inverse Fourier transform on the noise removal spectrum SRD to generate a signal AOD. Then, the IFFT unit 233 sends the generated signal AOD to the analog processing unit 160.
なお、放送受信装置100Cにおける低減ユニット156C以外の要素は、上述した放送受信装置100Bの場合と同様に動作する。
It should be noted that elements other than the reduction unit 156C in the broadcast receiving apparatus 100C operate in the same manner as in the broadcast receiving apparatus 100B described above.
以上説明したように、第3実施形態では、低減ユニット156Cが、ノイズ検出装置150Bにより検出されたノイズ周波数領域の周波数成分を、検波信号DTDから低減させる。したがって、第3実施形態のノイズ低減装置140Cによれば、ビートノイズ成分のエネルギー値や、音声信号のエネルギー値が変化しても、ビートノイズ成分を適切に低減させることができる。
As described above, in the third embodiment, the reduction unit 156C reduces the frequency component in the noise frequency region detected by the noise detection device 150B from the detection signal DTD. Therefore, according to the noise reduction device 140C of the third embodiment, the beat noise component can be appropriately reduced even if the energy value of the beat noise component or the energy value of the audio signal changes.
[実施形態の変形]
本発明は、上記の第1~第3実施形態に限定されるものではなく、様々な変形が可能である。 [Modification of Embodiment]
The present invention is not limited to the first to third embodiments described above, and various modifications can be made.
本発明は、上記の第1~第3実施形態に限定されるものではなく、様々な変形が可能である。 [Modification of Embodiment]
The present invention is not limited to the first to third embodiments described above, and various modifications can be made.
例えば、上記の第2実施形態から第3実施形態への変形と同様の変形を第1実施形態に対して施すようにしてもよい。
For example, a modification similar to the modification from the second embodiment to the third embodiment may be applied to the first embodiment.
また、周波数平均化の対象とする周波数幅は、音声帯域の全域の幅であってもよいし、サブバンド幅の所定複数倍であってもよい。
Further, the frequency width targeted for frequency averaging may be the entire width of the audio band, or a predetermined multiple of the subband width.
また、上記の第1~第3実施形態では、ノイズ周波数領域の検出にヒステリシス特性を有するようにした。これに対し、ノイズ周波数領域が検出された後にノイズ周波数領域が検出されなくなった場合には、ノイズ周波数領域が検出されなくなる直前に検出されたノイズ周波数領域の情報が所定時間にわたって低減ユニットへ送られるようにしてもよい。
In the first to third embodiments, the hysteresis frequency is detected in the noise frequency region. On the other hand, when the noise frequency region is not detected after the noise frequency region is detected, information on the noise frequency region detected immediately before the noise frequency region is not detected is sent to the reduction unit over a predetermined time. You may do it.
また、本発明では、ビートノイズ成分以外のエネルギーの周波数分布に応じて閾値カーブが変化する。このため、再生周波数特性として意図的に高域を減衰させたり、電界強度に応じて再生周波数特性を変化させる場合にも、適切なノイズ周波数領域の検出のために、本発明を適用してもよい。
In the present invention, the threshold curve changes according to the frequency distribution of energy other than the beat noise component. For this reason, even when the high frequency is intentionally attenuated as the reproduction frequency characteristic or the reproduction frequency characteristic is changed according to the electric field strength, the present invention can be applied to detect an appropriate noise frequency region. Good.
また、上記の第1~第3実施形態では、音声信号中におけるノイズ検出及びノイズ低減に本発明を適用したが、音声信号以外の信号中におけるノイズ検出及びノイズ低減に本発明を適用してもよい。
In the above first to third embodiments, the present invention is applied to noise detection and noise reduction in an audio signal. However, the present invention may be applied to noise detection and noise reduction in a signal other than an audio signal. Good.
なお、上記の第1~第3実施形態におけるノイズ検出装置及び低減ユニットを、DSP(Digital Signal Processor)等を備えた演算手段としてのコンピュータとして構成し、予め用意されたプログラムを当該コンピュータで実行することにより、上記の第1~第3実施形態における処理の一部又は全部を実行するようにしてもよい。このプログラムはハードディスク、CD-ROM、DVD等のコンピュータで読み取り可能な記録媒体に記録され、当該コンピュータによって記録媒体から読み出されて実行される。また、このプログラムは、CD-ROM、DVD等の可搬型記録媒体に記録された形態で取得されるようにしてもよいし、インターネットなどのネットワークを介した配信の形態で取得されるようにしてもよい。
The noise detection device and the reduction unit in the first to third embodiments described above are configured as a computer as a calculation unit including a DSP (Digital Signal Processor) and the like, and a program prepared in advance is executed on the computer. Accordingly, part or all of the processing in the first to third embodiments may be executed. This program is recorded on a computer-readable recording medium such as a hard disk, CD-ROM, or DVD, and is read from the recording medium and executed by the computer. The program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a form distributed via a network such as the Internet. Also good.
Claims (9)
- 入力した信号の周波数成分を第1周波数幅ごとに時間平均した結果に対して、前記第1周波数幅よりも広い第2周波数幅ごとに周波数軸に沿った周波数平均化を行って得た基準エネルギー値に基づき閾値カーブを生成する生成部と;
前記時間平均した結果が前記閾値カーブを超えるエネルギー値となっている周波数領域をノイズ周波数領域として検出する検出部と;
を備えることを特徴とするノイズ検出装置。 A reference energy obtained by performing frequency averaging along the frequency axis for each second frequency width wider than the first frequency width with respect to the result of time averaging the frequency components of the input signal for each first frequency width. A generator for generating a threshold curve based on the values;
A detection unit that detects, as a noise frequency region, a frequency region in which the time averaged result has an energy value exceeding the threshold curve;
A noise detection apparatus comprising: - 前記生成部は、前記基準エネルギー値に対してオフセット処理を行い、前記閾値カーブを生成する、ことを特徴とする請求項1に記載のノイズ検出装置。 The noise detection apparatus according to claim 1, wherein the generation unit performs an offset process on the reference energy value to generate the threshold curve.
- 前記オフセット処理は、前記基準エネルギー値の総和、前記時間平均の対象となった全周波数幅及び前記ノイズ周波数領域の推定周波数幅に基づいて行われる、ことを特徴とする請求項2に記載のノイズ検出装置。 3. The noise according to claim 2, wherein the offset processing is performed based on a total sum of the reference energy values, a total frequency width subjected to the time averaging, and an estimated frequency width of the noise frequency region. Detection device.
- 前記オフセット処理は、
前回の前記検出部によって前記ノイズ周波数領域が検出されなかった場合に行われる第1オフセット処理と、
前回の前記検出部によって前記ノイズ周波数領域が検出された場合に行われ、前記第1オフセット処理により得られる閾値カーブの場合の第1オフセット量よりも小さな第2オフセット量による第2オフセット処理と、
を含む、ことを特徴とする請求項2に記載のノイズ検出装置。 The offset process is
A first offset process performed when the noise frequency region is not detected by the previous detection unit;
A second offset process performed when the noise frequency region is detected by the previous detection unit, and a second offset amount that is smaller than the first offset amount in the case of the threshold curve obtained by the first offset process;
The noise detection device according to claim 2, further comprising: - 前記信号は音声信号である、ことを特徴とする請求項1に記載のノイズ検出装置。 The noise detection device according to claim 1, wherein the signal is an audio signal.
- 請求項1に記載のノイズ検出装置と;
前記ノイズ検出装置に入力した信号における前記ノイズ検出装置により検出されたノイズ周波数領域の成分を低減させる低減部と;
を備えるノイズ低減装置。 A noise detection device according to claim 1;
A reduction unit that reduces a noise frequency domain component detected by the noise detection device in a signal input to the noise detection device;
A noise reduction device comprising: - 生成部と、検出部とを備えるノイズ検出装置において使用されるノイズ検出方法であって、
前記生成部が、入力した信号の周波数成分を第1周波数幅ごとに時間平均した結果に対して、前記第1周波数幅よりも広い第2周波数幅ごとに周波数軸に沿った周波数平均化を行って得た基準エネルギー値に基づき閾値カーブを生成する生成工程と;
前記検出部が、前記時間平均した結果が前記閾値カーブを超えるエネルギー値となっている周波数領域をノイズ周波数領域として検出する検出工程と;
を備えることを特徴とするノイズ検出方法。 A noise detection method used in a noise detection apparatus including a generation unit and a detection unit,
The generation unit performs frequency averaging along the frequency axis for each second frequency width wider than the first frequency width with respect to the result of time averaging the frequency components of the input signal for each first frequency width. Generating a threshold curve based on the reference energy value obtained in the step;
A detection step in which the detection unit detects, as a noise frequency region, a frequency region in which the time-averaged result is an energy value exceeding the threshold curve;
A noise detection method comprising: - ノイズ検出装置が有するコンピュータに、請求項7に記載のノイズ検出方法を実行させる、ことを特徴とするノイズ検出プログラム。 A noise detection program causing a computer included in the noise detection apparatus to execute the noise detection method according to claim 7.
- ノイズ検出装置が有するコンピュータにより読み取り可能に、請求項8に記載のノイズ検出プログラムが記録されている、ことを特徴とする記録媒体。 9. A recording medium on which the noise detection program according to claim 8 is recorded so as to be readable by a computer included in the noise detection device.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2015/085325 WO2017104040A1 (en) | 2015-12-17 | 2015-12-17 | Noise detection device, noise reduction device, and noise detection method |
JP2017555942A JPWO2017104040A1 (en) | 2015-12-17 | 2015-12-17 | Noise detection device, noise reduction device, and noise detection method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2015/085325 WO2017104040A1 (en) | 2015-12-17 | 2015-12-17 | Noise detection device, noise reduction device, and noise detection method |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2017104040A1 true WO2017104040A1 (en) | 2017-06-22 |
Family
ID=59056104
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2015/085325 WO2017104040A1 (en) | 2015-12-17 | 2015-12-17 | Noise detection device, noise reduction device, and noise detection method |
Country Status (2)
Country | Link |
---|---|
JP (1) | JPWO2017104040A1 (en) |
WO (1) | WO2017104040A1 (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002149200A (en) * | 2000-08-31 | 2002-05-24 | Matsushita Electric Ind Co Ltd | Device and method for processing voice |
JP2009232439A (en) * | 2008-02-29 | 2009-10-08 | Sony Corp | Reception apparatus, reception method, and program |
JP2010187404A (en) * | 2010-05-10 | 2010-08-26 | Sony Corp | Communication device, noise removal method, and program |
JP2015156577A (en) * | 2014-02-20 | 2015-08-27 | パイオニア株式会社 | Broadcast receiver and noise rejection method |
-
2015
- 2015-12-17 WO PCT/JP2015/085325 patent/WO2017104040A1/en active Application Filing
- 2015-12-17 JP JP2017555942A patent/JPWO2017104040A1/en not_active Ceased
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002149200A (en) * | 2000-08-31 | 2002-05-24 | Matsushita Electric Ind Co Ltd | Device and method for processing voice |
JP2009232439A (en) * | 2008-02-29 | 2009-10-08 | Sony Corp | Reception apparatus, reception method, and program |
JP2010187404A (en) * | 2010-05-10 | 2010-08-26 | Sony Corp | Communication device, noise removal method, and program |
JP2015156577A (en) * | 2014-02-20 | 2015-08-27 | パイオニア株式会社 | Broadcast receiver and noise rejection method |
Also Published As
Publication number | Publication date |
---|---|
JPWO2017104040A1 (en) | 2018-10-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6263410B2 (en) | Broadcast receiving apparatus and noise removing method | |
JP2011188467A (en) | Broadcast receiving apparatus and method of determining presence of noise for broadcast receiving apparatus | |
JP2013038713A (en) | Audio signal processing circuit | |
JP5579640B2 (en) | Noise level detection device, reception device, and noise level detection method | |
JP5232121B2 (en) | Signal processing device | |
JP2016178473A (en) | Noise reduction device and noise reduction method | |
JP5484153B2 (en) | Broadcast receiving apparatus and broadcast signal processing method | |
JP2016092461A (en) | Noise reduction device and noise reduction method | |
WO2017104040A1 (en) | Noise detection device, noise reduction device, and noise detection method | |
JP6078358B2 (en) | Noise reduction device, broadcast reception device, and noise reduction method | |
JP5095444B2 (en) | Filter device, receiving device, and signal processing method | |
JP2009100068A (en) | Control device and relay device using same | |
US12039964B2 (en) | Audio processing system signal-level based temporal masking | |
JP6216546B2 (en) | Noise reduction device, broadcast reception device, and noise reduction method | |
CN102272833B (en) | Audio equipment and signal processing method thereof | |
JP2018074382A (en) | Noise detector and noise detection method | |
JP6126390B2 (en) | Noise reduction device, broadcast reception device, and noise reduction method | |
JP2019186593A (en) | Detection device, beat noise reduction device, and detection method | |
JP2017098868A (en) | Noise detector, noise reduction device and noise detection method | |
JP2009010841A (en) | Stereophonic demodulation device and its method | |
JP5145733B2 (en) | Audio signal processing apparatus, audio signal processing method, and program | |
JP6775275B2 (en) | Noise reduction device and noise reduction method | |
JP6084049B2 (en) | Filter control device and filter control method | |
JP6695716B2 (en) | Receiver and signal processing method | |
JP6263394B2 (en) | FM receiver and signal correction method |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 15910730 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2017555942 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 15910730 Country of ref document: EP Kind code of ref document: A1 |