WO2002035517A1 - Appareil et procédé pour interpoler un signal - Google Patents

Appareil et procédé pour interpoler un signal Download PDF

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Publication number
WO2002035517A1
WO2002035517A1 PCT/JP2001/005523 JP0105523W WO0235517A1 WO 2002035517 A1 WO2002035517 A1 WO 2002035517A1 JP 0105523 W JP0105523 W JP 0105523W WO 0235517 A1 WO0235517 A1 WO 0235517A1
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WIPO (PCT)
Prior art keywords
signal
band
frequency
component
interpolation
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PCT/JP2001/005523
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English (en)
Japanese (ja)
Inventor
Yasushi Sato
Original Assignee
Kabushiki Kaisha Kenwood
Kenwood Geobit Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2000324641A external-priority patent/JP3881836B2/ja
Priority claimed from JP2000366021A external-priority patent/JP3713200B2/ja
Application filed by Kabushiki Kaisha Kenwood, Kenwood Geobit Corporation filed Critical Kabushiki Kaisha Kenwood
Priority to AU2001266341A priority Critical patent/AU2001266341A1/en
Publication of WO2002035517A1 publication Critical patent/WO2002035517A1/fr

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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
    • G10L21/00—Processing of the speech or voice signal to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
    • G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
    • G10L21/0316—Speech enhancement, e.g. noise reduction or echo cancellation by changing the amplitude
    • G10L21/0364—Speech enhancement, e.g. noise reduction or echo cancellation by changing the amplitude for improving intelligibility

Definitions

  • the present invention relates to a signal interpolation device and a signal interpolation method for improving a spectrum distribution of a band-limited signal.
  • the method disclosed in Japanese Patent Application Laid-Open No. Hei 7-93900 discloses a method in which an output audio signal obtained by passing a PCM digital audio signal through a low-pass filter is converted into a signal including an absolute value component of the output signal. This is a method of causing distortion by multiplication.
  • the audio signal reproducing apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 7-93090 merely generates harmonics by distorting the waveform of the output audio signal using an absolute value circuit or the like. It is not known whether these harmonics can be approximated to those contained in the original audio signal.
  • Japanese Patent Application Laid-Open No. 6-85607 discloses that a tone component in which a fundamental tone and an overtone exist as a pair is extracted from an original audio signal, and the extracted tone component is used. A method is disclosed in which harmonic components on the higher frequency side than the band of the original audio signal are predicted and extrapolated to the original audio signal.
  • Japanese Patent Application No. 2000-179856 filed by the applicant of the present invention, discloses that the spectrum of the PCM signal is decomposed into a plurality of bands, and one of a pair of bands having a strong correlation.
  • a technique has been disclosed in which the spectrum component is added to the spectrum of the original PCM signal to generate a PCM signal having the spectrum after the spectrum component has been added. I have.
  • the added spectral component can be regarded as a part of the higher harmonic component of the original signal. Therefore, if the original signal is a band-limited signal, the spectral component is added. The signal having the later spectrum is closer to the original signal before the band is limited.
  • the spectrum of the signal represented by the decomposed spectrum is decomposed into bands by decomposing the spectrum of the original signal into bands.
  • a part called a pre-echo is added to the part just before the rise or just before the fall.
  • the bandwidth occupied by the pre-echo generally corresponds to the portion of the bandwidth occupied by the original speech that is close to the upper limit (for example, 10 km or more). For this reason, the sound represented by the signal having the spectrum after the spectral component has been added is a distortion of the high-frequency portion of the sound represented by the original signal.
  • the present invention has been made in view of the above situation, and has a signal interpolation device for restoring a signal close to the original signal with less distortion from a signal obtained by limiting the band of the original signal. And a signal interpolation method. Another object of the present invention is to provide a signal interpolation device and a signal interpolation method for restoring an audio signal with high sound quality.
  • a signal interpolating device has a frequency component in a specific frequency band of an original signal removed.
  • a signal interpolating device of the first invention has a frequency component in a specific frequency band of an original signal removed.
  • two bands in which the frequency components of the signal remain in the band-limited signal are selected, and the band components are extracted from each of the selected bands.
  • an input signal composed of the frequency component of the specific band from which the frequency component has been removed is synthesized, and the synthesized input signal is added to the band-limited signal. Operate.
  • the signal interpolation device of the first invention comprises a first filter for extracting a component in a first band of an input signal to be stored and a second filter for extracting a component in a second band of the input signal.
  • a second filter that extracts components
  • a mixing unit that mixes the components extracted by the first and second filters to generate a mixed signal
  • a third unit that generates a mixed signal by the mixing unit.
  • a third filter for extracting a component in the band of the third band, an addition unit for generating an output signal representing a sum of the component in the third band extracted by the third filter and the input signal, Consists of
  • a component constituting the input signal whose band has been limited in advance or a component corresponding to the sum or difference between its harmonic components is added to the input signal, and the bandwidth is reduced. Be extended. Since the added component can be regarded as a harmonic component of a part of the input signal, if the input signal is a band-limited signal, the input signal after the band is expanded is band-limited. It becomes close to the previous original signal. Therefore, if the input signal represents an audio signal, the audio signal is restored with high sound quality by restoring the audio signal using the input interpolated signal after the band is extended.
  • the bandwidth occupied by the first band is substantially equal to the bandwidth occupied by the second band; the upper limit of the first band is substantially equal to the lower limit of the second band; The upper limit of the band is substantially equal to the upper limit of the spectrum distribution of the input signal, the lower limit of the third band is substantially equal to the upper limit of the second band,
  • the first filter includes means for changing an upper limit and a lower limit of the first band in response to an instruction provided to the first filter, and the second filter responds to an instruction provided to the first filter. And means for changing the upper and lower limits of the second band, wherein the third filter changes the upper and lower limits of the third band in response to an instruction provided to the third filter. Means may be provided.
  • the signal interpolation device acquires the input signal, identifies an upper limit of the spectrum distribution of the acquired input signal, and, based on the identified result, the first to third bands. Determining an upper limit and a lower limit of the first band, providing an instruction to set the upper limit and the lower limit of the first band to a value determined by the user, and providing the second filter with Providing an instruction to set the upper and lower limits of the second band to a value determined by the user; and providing the third filter with an instruction to set the upper and lower limits of the third band to a value determined by the user.
  • the pass bands of the first to third filters are optimized by themselves.
  • Such a signal interpolating device extracts the envelope information representing the envelope of the spectrum of the input signal, acquires the component extracted by the third filter, and obtains the component of the acquired component.
  • the strength of the vector is indicated by the envelope information.
  • Equalizing means for filtering the component so as to be substantially equal to the intensity represented by the envelope and supplying the filtered component to the adding section, wherein the adding section includes a filter in the third band filtered by the equalizing means. And an output signal representing the sum of the input signal and the input signal.
  • the signal interpolation apparatus of the present invention converts the component to be added to the input signal whose band has been limited in advance into the input signal so as to follow the envelope of the spectrum of the input signal. to add. Therefore, the input signal after the band is extended is closer to the original signal before the band is limited.
  • the adder includes a delay unit that delays the input signal so that the components in the third band are substantially in phase with the components in the third band, and the component in the third band and the delay unit delay the input signal. As long as it generates the output signal representing the sum of the input signal and the input signal, even if any of the first to third filters and the mixing unit generates a signal delay, the addition is performed.
  • the unit accurately extends the bandwidth of the input signal.
  • a signal interpolator according to a second aspect of the present invention is a band-limited device that removes frequency components in a specific frequency band of an original signal.
  • one band in which the frequency component of the signal remains is selected from the band-limited signal, and the frequency component is extracted from the selected band.
  • Frequency component into a frequency component of another band thereby synthesizing an input signal composed of the frequency component of the specific band from which the frequency component has been removed, and converting the synthesized input signal to the band-limited signal. It works by adding to
  • the signal interpolation device of the second invention is a filter for extracting a component in a first band of an input signal to be interpolated, and a component in the first band extracted by the filter. To a second band on the higher frequency side than the band occupied by the input signal to generate an interpolation component. And an adder that generates an output signal representing the sum of the input signal and the interpolation component generated by the frequency converter.
  • a component obtained by frequency-converting a component constituting the input signal which has been subjected to band limitation is added to the input signal, and the band is extended. Since the added component can be regarded as a harmonic component of a part of the input signal, if the input signal is a band-limited signal, the input signal after the band has been expanded is before the band is limited. This is close to the original signal. Further, such a signal interpolation device does not perform a process of decomposing a spectrum into bands.
  • the audio signal is restored using the input signal whose band has been expanded, so that the audio signal is restored with low distortion and high sound quality.
  • the component added to the input signal is particularly good as a harmonic component of a part of the input signal. Because of the high likelihood of approximation, the input signal after the band extension is closer to the original signal before the band was limited.
  • the spectrum of the component added to the input signal is equal to the spectrum of the input signal.
  • the filter includes means for changing a range of the first band in response to an instruction supplied to the filter.
  • the frequency conversion unit may include means for changing a range of the second band in response to an instruction supplied to the frequency conversion unit.
  • the signal interpolation device obtains the input signal, specifies an upper limit of the spectrum distribution of the obtained input signal, and, based on the specified result, the first and second signals.
  • Determine the range of the band of said filter A step of providing an instruction to set the range of the first band to a range determined by the user, and a step of providing the frequency conversion unit with an instruction to set the range of the second band to a range determined by the user.
  • the interpolating device of the second invention extracts envelope information representing an envelope of the spectrum of the input signal, acquires the interpolation component generated by the frequency conversion unit, and obtains a spectrum of the acquired interpolation component.
  • an equalizing means for filtering the interpolation component and supplying the filtered component to the adder so that the intensity of the vector becomes substantially equal to the intensity represented by the envelope indicating the envelope information.
  • the adding unit may generate an output signal representing a sum of the input signal and the interpolation component filtered by the equalizing unit.
  • the signal interpolating device of the II invention adds the component to be added to the input signal to the input signal along the envelope of the spectrum of the input signal. Therefore, the input signal after the band is extended is closer to the original signal before the band is limited.
  • the adder includes a delay unit that delays the input signal so that the input signal is substantially in phase with the interpolation component, and the output representing a sum of the interpolation component and the input signal delayed by the delay unit. As long as it generates a signal, the adder accurately extends the bandwidth of the input signal even if one of the filter and the frequency converter generates a signal delay.
  • FIG. 1 is a diagram showing a configuration of a signal interpolator according to an embodiment of the present invention I.
  • FIG. 2 is a graph showing a band occupied by an input signal and a component added to the input signal in the first invention, and a pass band of BPF.
  • FIG. 3 is a diagram showing a configuration of a high-frequency signal interpolator according to the embodiment of the second invention.
  • FIG. 4 is a graph showing a band occupied by an input signal and a component added to the input signal in the second invention, and a pass band of a variable BPF.
  • a signal interpolator according to a first aspect of the present invention (the signal interpolator of the I-th invention) will be described by taking a frequency interpolator as an example.
  • FIG. 1 is a diagram showing a configuration of a frequency interpolator as an embodiment of the invention I. .
  • the frequency interpolator includes BPFs (bandpass filters) 1A, IB, and 4, a delay unit 2, a mixing unit 3, and an adding unit 5.
  • BPFs bandpass filters
  • the signals to be subjected to frequency interpolation by this frequency interpolator are simultaneously supplied to 8 to 18 and 18. Then, each of the signals supplied to itself passes a component within a pass band unique to itself, and supplies the signal to the mixing unit 3, while substantially blocking other components.
  • the input signal is a signal representing a voice or the like. It is assumed that the spectrum distribution of the sound or the like represented by the input signal corresponds to, for example, an original sound or the like from which a frequency component of a certain value or more (for example, 14 kHz or more) has been removed.
  • the range of the passband of BPF 1A and 1B is as shown in FIG.
  • the upper limit frequency of the pass band of BPF 1A (the band indicated as "BA” in Fig. 2) is the lower limit frequency of the pass band of BPF 1B (the band indicated as "BB” in Fig. 2).
  • the width of the pass band of the BPF 1A is the bandwidth of the band occupied by the component added to the input signal by performing frequency interpolation (the band shown as "B add" in Fig. 2). Almost equal to half,
  • the upper limit frequency of the BPF 1B passband is Frequency, which is almost equal to the upper limit frequency of the
  • the lower limit frequency of the pass band of BPF 1 A is f A or the upper limit frequency of the pass band of BPF 1 A is f AH
  • the lower limit frequency of the pass band of BPF 1 B is f B or BPF 1 B
  • the upper limit frequency of the band is f BH
  • the upper limit of the band occupied by the input signal is f IN
  • the bandwidth occupied by the component added to the input signal by frequency interpolation is w
  • f A or f AH , f B The values of f BH , f IN , and w have the relationships shown in equations (1) to (3).
  • the delay unit 2 is supplied with the same input signal as that supplied to BPF 1A and 1B simultaneously with BPF 1A and 1B. Then, the signal supplied to itself is delayed and supplied to the adder 5.
  • the length of time that the delay unit 2 delays the signal is the time that elapses before the components of the signal supplied to the BPFs 1A and 1B are supplied to the addition unit 5 via the mixing unit 3 and the BPF 4. Shall be substantially equal to the length.
  • phase of the delayed input signal supplied from the delay unit 2 to the addition unit 5 and the phase of the signal supplied from the BPF 4 to the addition unit 5 are the same as those of the signals supplied to the addition unit 5 at the same time. It is assumed that the phases are substantially the same.
  • the mixing unit 3 mixes the components supplied from the BPFs 1A and 1B with each other, thereby forming a product of the component passing through the BPF 1A or its harmonic and the component passing through the BPF 1B or its harmonic. Then, a signal is generated, and the generated signal is supplied to the BPF 4.
  • the BPF 4 passes components occupying a band whose lower limit of the frequency is f IN and whose upper limit of the frequency is (f IN + w) among the components supplied from the mixing unit 3. It is supplied to the adder 5 to substantially block other components.
  • the adder 5 generates a signal representing the sum of the delayed input signal supplied to itself from the delay unit 2 and the component supplied from the BPF 4, and outputs the signal as an output signal of the frequency interpolator.
  • the input signal (ie, output signal) is the product of the input signal component that passed BPF 1A or its harmonics and the input signal component that passed BPF 1B or its harmonics.
  • a component occupying a band whose lower limit of frequency is f IN and whose upper limit of frequency is (f IN + w) is composed of a signal obtained by adding to the input signal.
  • the component added to the input signal is composed of some harmonic components of the input signal, if the input signal is a band-limited signal, the output signal is the input signal before the band is limited. It becomes something close to.
  • This frequency interpolator is not limited to the above.
  • BPF 1 A, BPF 1 B, delay unit 2, mixing unit 3, BPF 4, and adder unit 5 may be implemented by DSP (Digital Signala 1 Processor) or CPU (Central Processing Un it) may be done.
  • DSP Digital Signala 1 Processor
  • CPU Central Processing Un it
  • each value of I Alpha have ⁇ ⁇ , f BL, f BH , ⁇ IN, and w do not necessarily need to have a relationship shown in Equation 1 Equation 3.
  • Equations 1 to 3 it is highly likely that the components of the input signal passing through the BPFs 1A and 1B can be regarded as harmonic components of a part of the input signal itself. . Further, the spectrum of the component passing through BPF4 is adjacent to the spectrum of the input signal without any gap on the high frequency side. Thus, if the input signal represents a band-limited audio signal, the output signal will be closer to the input signal before the band was limited.
  • the BPFs 1A, IB, and 4 may change their passbands by a known method according to instructions supplied to them.
  • This frequency interpolator has two passbands for BPF 1A, IB and 4. May be provided.
  • the control unit includes, for example, a Fourier transform unit and an analysis unit, and each of the control units includes, for example, a DSP or a CPU.
  • the Fourier transform unit obtains the input signal, performs Fourier transform, and generates a signal representing a spectrum obtained as a result of the Fourier transform.
  • the analysis unit specifies a component having the highest frequency among the components of the spectrum indicated by the signal generated by the Fourier transform unit, and determines the specified spectrum frequency as the above-described value of f IN .
  • the analysis unit compares the value of the determined ⁇ ⁇ , based on the predetermined value indicating the upper limit of the frequency components to be added to the input signal, determines the value of the above w, determined f Iotanyu and values of w Further, the values of f A or f AH , f BL, and ⁇ ⁇ are determined. Then, an instruction to change the pass band so that the determined values of f AL and: f AH become the lower and upper limits of the pass band of BPF 1A is supplied to BP FI A. BPF 1 to of B, and supplies the instruction value of the determined f BL and f B H changes the pass ⁇ as the lower limit and upper limit of the pass band of the BPF 1 B. The BPF 4 is supplied with an instruction to change the pass band so that the determined values of f IN and (f IN + w) are the lower and upper limits of the pass band of the BPF 4.
  • the frequency interpolator may determine the intensity of the spectrum of the component to be added to the input signal by extrapolating to the envelope of the spectrum of the input signal.
  • this frequency interpolator includes an equalizer, and this equalizer filters the components to be supplied to the adding unit 5 by the BPF 4 so as to match the frequency characteristics indicated by the signal supplied to itself. After that, it is supplied to the addition unit 5.
  • the above-described analysis unit performs a regression calculation process based on the signal generated by the above-described Fourier transform unit, thereby specifying a function that forms an envelope of a spectrum of the input signal, and based on the specified function, Determine the frequency characteristics of the output signal in the band where the lower limit frequency is f IN and the upper limit frequency is (f IN + w). Then, a signal indicating the determination result is supplied to the above-described equalizer.
  • the frequency interpolating apparatus according to the present invention can be realized using an ordinary computer system without using a dedicated system.
  • a program for executing the operations of the BPFs 1A, IB and 4, the delay unit 2, the mixing unit 3, the adding unit 5, the control unit, and the equalizer described above in a personal computer or a microcomputer By installing the program from a stored medium (CD-ROM, MO, floppy disk, etc.), a frequency interpolator that executes the above-described processing can be configured.
  • a stored medium CD-ROM, MO, floppy disk, etc.
  • the program may be posted on a bulletin board (BBS) of a communication line and distributed via the communication line.
  • BSS bulletin board
  • a carrier wave is modulated by a signal representing the program, and the obtained modulated wave May be transmitted, and the device receiving the modulated wave may demodulate the modulated wave and restore the program.
  • a program excluding the part is stored in the recording medium. May be. Also in this case, in the present invention, it is assumed that the recording medium stores a program for executing each function or step executed by the computer.
  • a signal interpolation device (the signal interpolation device of the II invention) will be described by taking a high-frequency signal interpolator as an example.
  • FIG. 3 is a diagram showing a configuration of a high-frequency signal interpolator as an embodiment of the II invention.
  • the high-frequency signal interpolator includes a variable BPF (bandpass filter) 31, a delay unit 32, a spectrum analysis unit 33, and a variable frequency generator. It comprises a vibration section 34, a mixing section 35, a variable HPF (high pass filter) 36, and an addition section 37.
  • BPF bandpass filter
  • HPF high pass filter
  • the variable BPF 31 is supplied with a signal (input signal) to be subjected to spectrum interpolation by the high-frequency signal interpolator, and the input signal supplied to the variable BPF 31 is supplied from the spectrum analyzer 33.
  • the input signal is a signal representing a voice or the like.
  • Spectral distribution of voice or the like which the input signal is represented, for example, above a certain value of such original audio (e.g., 14 or more kHz) c delay unit 32 to correspond to that frequency component of has been removed, the variable
  • the same input signal as that supplied to the BPF 31 is supplied simultaneously with the variable BPF 31. Then, the input signal supplied to itself is delayed and supplied to the adder 37.
  • the spectrum analysis unit 33 is composed of, for example, DSP (DigitalSigna1Procssor), CPU, CentrallProcessIngUnit), and the like.
  • the spectrum analysis unit 33 is supplied with the same input signal as that supplied to the variable BPF 31 at the same time as the variable BPF 31. Then, the supplied input signal is analyzed, and based on the analysis result, the first control signal specifying the pass band of the variable BPF 31 and the frequency of a local oscillation signal generated by the variable frequency A second control signal that specifies the passband of the variable HPF 36 is generated. And the first generated The control signal is supplied to the variable BPF 31, the second control signal is supplied to the variable frequency oscillator 34, and the third control signal is supplied to the variable HPF 36.
  • the spectrum analyzer 33 performs the processing described as (1) to (4) below.
  • the spectrum analyzer 33 Fourier-transforms the input signal supplied to itself. Then, the component having the highest frequency among the components of the spectrum obtained as a result of the Fourier transform is extracted, and the frequency of the extracted component is specified as the upper limit value of the band occupied by the input signal.
  • the spectrum analysis unit 33 performs spectrum interpolation based on the upper limit value of the band occupied by the input signal and a predetermined value indicating the upper limit frequency of the component to be added to the input signal. Determines the bandwidth occupied by the component added to the input signal.
  • the spectrum analyzer 32 calculates the passbands of the variable BPF 31 and the variable HPF 36 and the local oscillation signal so as to satisfy the following conditions (a) to (d). Determine the frequency. That is, as shown in FIG.
  • the upper limit frequency of the passband of the variable BPF 31 (the band shown as “BA” in Fig. 4) is the upper limit frequency of the band occupied by the input signal (the band shown as “Bin” in Fig. 4). Substantially equal to the frequency,
  • the width of the pass band of the variable BPF 31 is determined by the band occupied by the component added to the input signal by performing spectrum interpolation (see FIG. 4).
  • the frequency of the local oscillation signal (the frequency indicated as “ f.sc ” in FIG. 4 and the present specification) is substantially equal to the difference between the upper and lower limits of the passband of the variable BPF 31;
  • the lower limit of the passband of the variable HP F36 (the band shown as “BB” in Fig. 4) is the frequency f of the local oscillation signal. greater than the maximum absolute value of the difference between sc and the frequency belonging to band B add,
  • variable BPF 31 and the variable HP F 36 Determine the passband and the frequency of the local oscillation signal.
  • the lower limit frequency of the pass band of the variable BPF 31 is f H
  • the upper limit frequency of the pass band of the variable BPF 31 is f HH
  • the upper limit of the band occupied by the input signal is f.
  • the lower limit of the band occupied by the component added to the input signal by spectrum interpolation is f IL
  • the lower limit of the band occupied by the component added to the input signal by spectrum interpolation is f IH
  • the input is made by spectrum interpolation BW bandwidth occupied by the component that is added to the signal, when the frequency of the lower limit of the passband of the variable HP F 6 and i HPF, f H have f HH, fo, fi L> f IH, BW, f HPF and
  • the values of f osc have substantially the relationships shown in Equations (4) to (6).
  • the spectrum analyzer 33 satisfies the above conditions (a) to (d). Using the values of HH and f HIj , the center frequency (ie, the value of ⁇ (f HH — f HL ) / 2 ⁇ ) and the bandwidth (ie, (f H H— f HL ) is determined. Then, a first control signal that specifies these determined values as the center frequency and the bandwidth value of the pass band of the variable BPF 31 is generated and supplied to the variable BPF 31.
  • a second control signal that specifies the value of f osc that satisfies the above conditions (a) to (d) as the frequency of the local oscillation signal is generated and supplied to the variable frequency oscillator 34.
  • a third control signal that specifies the value of f HPF that satisfies the above conditions (a) to (d) as the lower limit frequency of the pass band of the variable HP F 36 is generated, and Supply.
  • the high-frequency signal interpolator calculates the value of ⁇ ⁇ ⁇ ⁇ , for example, f. A sufficiently higher predetermined value may be used.
  • variable frequency oscillator 34 When supplied with the second control signal from the spectrum analyzer 33, the variable frequency oscillator 34 generates a local oscillation signal composed of a signal of the frequency indicated by the second control signal, and generates the generated local oscillation signal.
  • the signal is supplied to the mixing section 35.
  • the mixing unit 35 is composed of, for example, a multiplication circuit and the like.
  • the mixing unit 35 mixes the component supplied from the variable BPF 1 and the local oscillation signal generated by the variable frequency oscillating unit 34 with each other, so that the product of the component passing through the variable BPF 31 and the local oscillation signal is mixed. Is generated, and the generated signal is supplied to the variable HP F36.
  • the signal supplied from the mixing unit 35 to the variable HPF 36 includes a component having a frequency corresponding to the sum of the frequency of the component passing through the variable BPF 31 and the frequency of the local oscillation signal (sum component) and the variable BPF 31 And a component having a frequency corresponding to the difference between the frequency of the component that has passed through and the frequency of the local oscillation signal (difference component).
  • variable HPF 6 passes the component indicated by the third control signal supplied from the spectrum analysis unit 33 out of the components supplied from the mixing unit 35 through a component within a pass band having a lower limit of the frequency and adds the values. Feed part 37 to substantially block other components.
  • the sum vector of the difference component supplied to the variable HP F 36 by the mixing unit 35 is the lower one of the lower values of the frequencies I f HL — f osc I and I f HH _ f osc I. Occupies the band whose value is the upper limit.
  • the lower limit frequency f HPF of the pass band of the variable HP F 36 satisfies the above condition (d) (the condition shown in Expression (6)).
  • variable HPF 36 passes the sum component of the signal supplied by the mixing unit 35 and supplies it to the adding unit 37, thereby substantially blocking the difference component.
  • the adder 37 generates a signal representing the sum of the delayed input signal supplied to itself from the delay unit 32 and the component supplied from the variable HPF 6, and outputs the signal as an output signal of the high-frequency signal interpolator. I do.
  • the output signal should be such that the input signal contains components within a continuous band including the spectrum with the highest frequency of the input signal, in a band adjacent to the upper limit of the band occupied by the input signal on the high frequency side.
  • the configuration of this high-frequency signal interpolator is not limited to the above.
  • variable BPF 31 the delay unit 32, the variable frequency oscillation unit 34, the mixing unit 35, the variable HP F 36, and the addition unit 37 may be implemented by a DSP (Digita 1 Signal 1 P rocessor) or CPU (Centra 1 P rocessing Un it).
  • the passbands of the variable BPF 31 and the variable HPF 36 and the frequency of the local oscillation signal are determined by the above-mentioned conditions (a) to (d) (the conditions shown by the equations (4) to (6)). May be fixed in advance to a value that matches. In this case, the high-frequency signal interpolator does not need to include the spectrum analyzer 33.
  • the signal added to the input signal via frequency conversion need not include the highest frequency spectrum of the input signal.
  • the signal added to the input signal through frequency conversion contains the highest frequency spectrum of the input signal, this signal is added to the input signal. Is likely to be considered as a harmonic component of a part of the input signal itself. Thus, if the input signal represents a band-limited audio signal, the output signal will be closer to the input signal before the band was limited.
  • f H have f HH f. , F IL , f IH , BW, f HPF and f osc have the relationships shown in Equations (4) to (6), the spectrum of the component passing through the variable HP F 36 is It is adjacent to the spectrum without any gaps on the high frequency side. Therefore, the input signal is band limited If the audio signal represents an audio signal, the output signal is closer to the input signal before the band is limited.
  • the high-frequency signal interpolator may determine the intensity of the spectrum of the component to be added to the input signal by extrapolating to the spectrum envelope of the input signal.
  • this high-frequency signal interpolator further includes an envelope analysis unit and an equalizer.
  • the equalizer filters the components to be supplied to the adding unit 37 by the variable HPF 36 so as to match the frequency characteristics indicated by the signal supplied to itself, and then supplies the components to the adding unit 37.
  • the envelope analysis unit performs a regression calculation process based on the spectrum obtained as a result of the Fourier transform of the input signal by the spectrum analysis unit 33, thereby obtaining a function that forms an envelope of the spectrum of the input signal. Identify. Then, a function identified, the scan Bae spectrum analyzer 3 3 f IL and was determined: Based on the values of f the IH, the output signal of the band lower limit of the frequency is the frequency of the upper limit in f IL is f the IH Is determined, and a signal indicating the determination result is supplied to the above-described equalizer.
  • the spectrum analyzer 33 may supply the data representing the spectrum obtained as a result of the Fourier transform of the input signal to the envelope analyzer, and the envelope analyzer may, for example, The value of f I] L may be obtained by obtaining the third control signal described above.
  • the signal interpolation device according to the present invention can be realized using an ordinary computer system without using a dedicated system.
  • variable BPF 1 For example, the above-mentioned variable BPF 1, delay section 32, spectrum analysis section 33, variable frequency oscillation section 34, mixing section 35, variable HPF 36, , An adder 7, an envelope analyzer, and a medium (CD-ROM, MO, floppy disk, etc.) storing a program for executing the operation of the equalizer.
  • the high-frequency signal interpolator By installing the high-frequency signal interpolator, the high-frequency signal interpolator that executes the above-described processing can be configured.
  • the program may be posted on a bulletin board (BBS) of a communication line and distributed via the communication line.
  • BSS bulletin board
  • a carrier wave is modulated by a signal representing the program, and the obtained modulated wave May be transmitted, and the device receiving the modulated wave may demodulate the modulated wave and restore the program.
  • a program excluding the part is stored in the recording medium. It may be stored. Also in this case, in the present invention, it is assumed that the recording medium stores a program for executing each function or step executed by the computer.
  • a signal interpolation device and a signal interpolation method for effectively restoring a signal close to the original signal from a signal in which a specific band of the original signal is restricted are realized. Is done.

Abstract

Selon cette invention, un signal d'interpolation est ajouté à un signal à bande limitée généré par élimination des composants de fréquence dans une bande de fréquence spécifiée d'un signal original, et le signal résultant est émis en sortie. Le signal d'interpolation est synthétisé par sélection de deux bandes dans lesquelles les composants de fréquence du signal à bande limitée subsistent, et ensuite par mélange des deux composants de bande extraits respectivement des bandes sélectionnées, ou par sélection d'une bande dans laquelle les composants de fréquence du signal à bande limitée subsistent et ensuite par conversion d'un composant de fréquence extrait d'un bande sélectionnée en composant de l'autre bande. Un signal proche du signal original peut ainsi être rétabli à partir d'un signal à bande limitée généré à l'aide d'un signal produit par limitation de la bande du signal original. Alternativement, un signal audio peut être rétabli avec une qualité de son élevée.
PCT/JP2001/005523 2000-10-24 2001-06-27 Appareil et procédé pour interpoler un signal WO2002035517A1 (fr)

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AU2001266341A AU2001266341A1 (en) 2000-10-24 2001-06-27 Apparatus and method for interpolating signal

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JP2000324641A JP3881836B2 (ja) 2000-10-24 2000-10-24 周波数補間装置、周波数補間方法及び記録媒体
JP2000-324641 2000-10-24
JP2000-366021 2000-11-30
JP2000366021A JP3713200B2 (ja) 2000-11-30 2000-11-30 信号補間装置、信号補間方法及び記録媒体

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US7318034B2 (en) 2002-06-07 2008-01-08 Kabushiki Kaisha Kenwood Speech signal interpolation device, speech signal interpolation method, and program
US7577259B2 (en) 2003-05-20 2009-08-18 Panasonic Corporation Method and apparatus for extending band of audio signal using higher harmonic wave generator

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JP2000036755A (ja) * 1998-05-15 2000-02-02 Sony Corp 符号変換方法及び装置、並びにプログラム供給媒体
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JPH02235424A (ja) * 1989-03-09 1990-09-18 Fujitsu Ltd 時間切替型帯域分割音声符号化方式および装置
JPH03254223A (ja) * 1990-03-02 1991-11-13 Eastman Kodak Japan Kk アナログデータ伝送方式
JPH0685607A (ja) * 1992-08-31 1994-03-25 Alpine Electron Inc 高域成分復元装置
JPH06222799A (ja) * 1992-10-09 1994-08-12 American Teleph & Telegr Co <Att> 音声信号の符号化方法と符号化音声信号の復号化方法およびそのシステム
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7318034B2 (en) 2002-06-07 2008-01-08 Kabushiki Kaisha Kenwood Speech signal interpolation device, speech signal interpolation method, and program
US7676361B2 (en) 2002-06-07 2010-03-09 Kabushiki Kaisha Kenwood Apparatus, method and program for voice signal interpolation
US7577259B2 (en) 2003-05-20 2009-08-18 Panasonic Corporation Method and apparatus for extending band of audio signal using higher harmonic wave generator

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