JP2002175092A - Signal interpolation apparatus, signal interpolation method and recording medium - Google Patents

Signal interpolation apparatus, signal interpolation method and recording medium

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Publication number
JP2002175092A
JP2002175092A JP2000372594A JP2000372594A JP2002175092A JP 2002175092 A JP2002175092 A JP 2002175092A JP 2000372594 A JP2000372594 A JP 2000372594A JP 2000372594 A JP2000372594 A JP 2000372594A JP 2002175092 A JP2002175092 A JP 2002175092A
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JP
Japan
Prior art keywords
signal
interpolation
spectrum
interpolated
band
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
JP2000372594A
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Japanese (ja)
Other versions
JP3887531B2 (en
Inventor
Yasushi Sato
寧 佐藤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kenwood KK
Original Assignee
Kenwood KK
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Application filed by Kenwood KK filed Critical Kenwood KK
Priority to JP2000372594A priority Critical patent/JP3887531B2/en
Priority to PCT/JP2001/005264 priority patent/WO2002050814A1/en
Priority to AU2001274567A priority patent/AU2001274567A1/en
Publication of JP2002175092A publication Critical patent/JP2002175092A/en
Application granted granted Critical
Publication of JP3887531B2 publication Critical patent/JP3887531B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
    • G11B20/1876—Interpolating methods

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a frequency interpolation apparatus, etc., for restoring modulated waves obtained by using a signal limiting the band of an original signal to the signal which approximates the original signal or storing an audio signal with high sound quality. SOLUTION: A PCM signal is transformed into spectra of a complex type by a Fourier transform section 1. An interpolation band analysis section 3 specifies the band to be interpolated, which is the object of the interpolation among these spectra and a reference band used for the purpose of interpolation. A signal interpolation processing section 4 obtains the spectra of the band to be interpolated, after the interpolation by inferring the envelope of the PCM signal and extrapolating the spectra of the same spectral distribution as the spectral distribution within the reference band into the band to be interpolated so as to comply with the function of the envelope. An inverse Fourier transform section 5 forms a PCM signal, having the spectra of the band to be interpolated after the interpolation and an interpolation band adder section 6 forms an output signal, by adding the PCM signal formed by the inverse Fourier transforms section 5 and the PCM signal delayed by a delay section 2.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】この発明は、変調された信号
のスペクトル分布を改善する信号補間装置及び信号補間
方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal interpolation device and a signal interpolation method for improving the spectrum distribution of a modulated signal.

【０００２】[0002]

【従来の技術】ＭＰ３（MPEG1 audio layer 3）形式の
データの配信、及び、ＦＭ（FrequencyModulation）放
送やテレビジョン音声多重放送等の手法による音楽など
の供給が近年盛んになっている。これらの手法では、帯
域が過度に広くなることによるデータ量の増大や占有帯
域幅の広がりを避けるため、一般に、供給する対象の音
楽等のうち約１５ｋＨｚ以上の周波数成分が除去されて
いる。2. Description of the Related Art In recent years, distribution of data in an MP3 (MPEG1 audio layer 3) format and supply of music and the like by means of FM (Frequency Modulation) broadcasting and television audio multiplex broadcasting have become popular. In these methods, in order to avoid an increase in the amount of data and an increase in occupied bandwidth due to an excessively wide band, generally, a frequency component of about 15 kHz or more is removed from music to be supplied.

【０００３】このように、一定値以上の周波数成分が除
去された音楽等は通常、音質が悪い。そこで、除去され
た周波数成分に代わる信号を加算することが考えられ
る。このための手法としては、特開平７−９３９００号
公報に開示されている手法や、特開平６−８５６０７号
公報に開示されている手法がある。[0003] As described above, music or the like from which a frequency component equal to or higher than a certain value is removed usually has poor sound quality. Therefore, it is conceivable to add a signal in place of the removed frequency component. As a technique for this, there is a technique disclosed in JP-A-7-93900 and a technique disclosed in JP-A-6-85607.

【０００４】特開平７−９３９００号公報に開示されて
いる手法は、ＰＣＭディジタルオーディオ信号をローパ
スフィルタに通して得られる出力オーディオ信号を、当
該出力信号の絶対値成分を含む信号を乗算することによ
り歪みを生じさせる、という手法である。A technique disclosed in Japanese Patent Application Laid-Open No. 7-93900 is to multiply an output audio signal obtained by passing a PCM digital audio signal through a low-pass filter by a signal containing an absolute value component of the output signal. This is a method of causing distortion.

【０００５】特開平６−８５６０７号公報に開示されて
いる手法は、原オーディオ信号から基音と倍音が組で存
在する音色成分を抽出して、抽出した音色成分を用い、
原オーディオ信号の帯域より高域側の倍音成分を予測し
て原オーディオ信号に外挿する、という手法である。The technique disclosed in Japanese Patent Application Laid-Open No. 6-85607 extracts a tone component in which a fundamental tone and a harmonic exist as a set from an original audio signal, and uses the extracted tone component.
This is a method 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.

【０００６】[0006]

【発明が解決しようとする課題】しかし、特開平７−９
３９００号公報のオーディオ信号再生装置は、出力オー
ディオ信号の波形を絶対値回路等を用いて歪ませること
により高調波を発生させるに過ぎないものであって、こ
の高調波は元のオーディオ信号に含まれているものに近
似し得るものであるかは分からない。However, Japanese Patent Laid-Open No. 7-9 / 1995
The audio signal reproducing apparatus disclosed in Japanese Patent No. 3900 merely generates a harmonic by distorting the waveform of an output audio signal using an absolute value circuit or the like, and the harmonic is included in the original audio signal. I do not know if it can be approximated.

【０００７】また、元の音声等の帯域を制限して得られ
る原オーディオ信号に特開平６−８５６０７の手法を適
用した場合、純音の音色成分について倍音成分を予測し
て外挿することができず、同様に、帯域が制限された結
果倍音成分を除去された音色成分についても、除去され
た倍音成分を推測して外挿することができない。Further, when the method of JP-A-6-85607 is applied to an original audio signal obtained by limiting the band of the original sound or the like, it is possible to predict and extrapolate the overtone component of the timbre component of the pure tone. Similarly, it is not possible to extrapolate a timbre component from which a harmonic component has been removed as a result of the band limitation by estimating the removed harmonic component.

【０００８】この発明は、上記実状に鑑みてなされたも
のであり、原信号の帯域を制限した信号を用いて得られ
る変調波から原信号に近い信号を復元できるようにする
ための信号補間装置及び信号補間方法を提供することを
目的とする。また、この発明は、オーディオ信号を高音
質で復元するための信号補間装置及び信号補間方法を提
供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and has a signal interpolating apparatus for restoring a signal close to an original signal from a modulated wave obtained by using a signal whose band of the original signal is limited. 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.

【０００９】[0009]

【課題を解決するための手段】上記目的を達成するべ
く、この発明の第１の観点に係る信号補間装置は、補間
される対象である被補間信号に基づき、当該被補間信号
が表す値をフーリエ変換して得られる複素形式のスペク
トルの虚数部及び実数部を表す信号を生成するスペクト
ル分布生成手段と、前記スペクトルが占める帯域に含ま
れる補間用帯域を特定する帯域特定手段と、前記スペク
トルが実質的に分布しない被補間帯域を特定し、特定し
た当該被補間帯域内のスペクトルの実数部の分布が、前
記帯域特定手段により特定された前記補間用帯域内のス
ペクトルの実数部の分布と実質的に同一であり、特定し
た当該被補間帯域内のスペクトルの虚数部の分布が、前
記帯域特定手段により特定された前記補間用帯域内のス
ペクトルの虚数部の分布と実質的に同一であるような補
間用成分を生成する補間手段と、前記被補間信号と前記
補間用成分との和を表す出力信号を生成する加算部と、
を備える、ことを特徴とする。In order to achieve the above object, a signal interpolating apparatus according to a first aspect of the present invention calculates a value represented by an interpolated signal based on an interpolated signal to be interpolated. Spectrum distribution generating means for generating a signal representing an imaginary part and a real part of a complex form spectrum obtained by Fourier transform, a band specifying means for specifying an interpolation band included in a band occupied by the spectrum, and the spectrum An interpolated band that is not substantially distributed is specified, and the distribution of the real part of the specified spectrum in the interpolated band is substantially the same as the distribution of the real part of the spectrum in the interpolation band specified by the band specifying unit. The distribution of the imaginary part of the spectrum in the interpolated band specified is the imaginary part of the spectrum in the interpolation band specified by the band specifying means. And interpolation means for generating a cloth and substantially interpolation component as the same, an adder for generating an output signal representing the sum of the object interpolation signal and the interpolation components,
It is characterized by having.

【００１０】このような信号補間装置によれば、スペク
トルの実数部及び虚数部の分布が被補間信号のスペクト
ルの一部と実質的に同一であるような成分が被補間信号
に追加され、帯域が拡張される。追加された成分は、被
補間信号の一部分の高調波成分とみなし得るので、被補
間信号が帯域を制限された信号である場合、帯域が拡張
された後の被補間信号は、帯域が制限される前の原信号
に近いものとなる。また、複素形式のスペクトルの実数
部及び虚数部が共に追加されるので、追加された成分の
位相は、帯域の制限により除去された成分の位相に近い
ものとなる。従って、被補間信号がオーディオ信号を表
すものであれば、帯域が拡張された後の被補間信号を用
いてオーディオ信号を復元することにより、オーディオ
信号が低歪み、高音質で復元される。According to such a signal interpolation device, a component whose distribution of the real part and the imaginary part of the spectrum is substantially the same as a part of the spectrum of the signal to be interpolated is added to the signal to be interpolated, Is expanded. Since the added component can be regarded as a harmonic component of a part of the interpolated signal, if the interpolated signal is a band-limited signal, the interpolated signal after the band is extended is band-limited. The original signal is close to the original signal. Also, since both the real part and the imaginary part of the complex spectrum are added, the phase of the added component is close to the phase of the component removed due to band limitation. Therefore, if the interpolated signal represents an audio signal, the audio signal is restored with low distortion and high sound quality by restoring the audio signal using the interpolated signal whose band has been expanded.

【００１１】前記補間用帯域の上限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しいものであれ
ば、被補間信号に追加される成分は、被補間信号の一部
分の高調波成分に特によく近似し得る可能性が高い。従
って、帯域が拡張された後の被補間信号は、帯域が制限
される前の原信号により近いものとなる。If the upper limit of the interpolation band is substantially equal to the upper limit of the spectrum distribution of the signal to be interpolated, the component added to the signal to be interpolated is a harmonic component of a part of the signal to be interpolated. It is highly likely that it can be particularly well approximated. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００１２】前記被補間帯域の下限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しいものであれ
ば、被補間信号に追加される成分のスペクトルは、被補
間信号のスペクトルと、高周波側で隙間なく隣接するも
のとなる。従って、帯域が拡張された後の被補間信号
は、帯域が制限される前の原信号により近いものとな
る。If the lower limit of the interpolated band is substantially equal to the upper limit of the distribution of the spectrum of the interpolated signal, the spectrum of the component added to the interpolated signal includes the spectrum of the interpolated signal and Adjacent without a gap on the high frequency side. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００１３】前記補間手段は、例えば、前記被補間信号
のスペクトルの絶対値の包絡線を表す包絡線情報を抽出
する手段と、前記補間用成分のスペクトルの強度を、当
該補間用成分のスペクトルの絶対値の強度が前記包絡線
情報が示す包絡線により表される強度に実質的に等しく
なるように変更して前記加算部に供給する手段と、を備
えていてもよい。この場合、前記加算部は、前記被補間
信号とスペクトルの強度が変更された前記補間用成分と
の和を表す出力信号を生成するものであればよい。この
ような構成を有することにより、前記信号補間装置は、
被補間信号に追加されるべき成分を、そのスペクトルの
絶対値が被補間信号のスペクトルの包絡線に沿うように
して被補間信号に追加する。従って、帯域が拡張された
後の被補間信号は、帯域が制限される前の原信号により
近いものとなる。The interpolation means includes, for example, means for extracting envelope information representing the envelope of the absolute value of the spectrum of the signal to be interpolated, and the intensity of the spectrum of the interpolation component. Means for changing the magnitude of the absolute value to be substantially equal to the magnitude represented by the envelope indicated by the envelope information and supplying the magnitude to the adder. In this case, the adder may generate an output signal representing the sum of the interpolated signal and the interpolation component whose spectrum intensity has been changed. With such a configuration, the signal interpolation device
The component to be added to the interpolated signal is added to the interpolated signal such that the absolute value of the spectrum is along the envelope of the spectrum of the interpolated signal. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００１４】前記補間手段は、例えば、前記被補間信号
のスペクトルの実数部の包絡線を表す第１の包絡線情報
及び前記被補間信号のスペクトルの虚数部の包絡線を表
す第２の包絡線情報を抽出する手段と、前記補間用成分
のスペクトルの強度を、当該補間用成分のスペクトルの
実数部の強度が前記第１の包絡線情報が示す包絡線によ
り表される強度に実質的に等しくなり、且つ、当該補間
用成分のスペクトルの虚数部の強度が前記第２の包絡線
情報が示す包絡線により表される強度に実質的に等しく
なるように変更して前記加算部に供給する手段と、を備
えていてもよい。この場合、前記加算部は、前記被補間
信号とスペクトルの強度が変更された前記補間用成分と
の和を表す出力信号を生成するものであればよい。この
ような構成を有することにより、前記信号補間装置は、
被補間信号に追加されるべき成分を、そのスペクトルの
実数部が被補間信号のスペクトルの実数部の包絡線に沿
い、虚数部が被補間信号のスペクトルの虚数部の包絡線
に沿うようにして被補間信号に追加する。従って、帯域
が拡張された後の被補間信号は、帯域が制限される前の
原信号により近いものとなる。[0014] The interpolation means includes, for example, first envelope information representing an envelope of a real part of the spectrum of the signal to be interpolated and a second envelope representing an envelope of an imaginary part of the spectrum of the signal to be interpolated. Means for extracting information, the intensity of the spectrum of the interpolation component, the intensity of the real part of the spectrum of the interpolation component is substantially equal to the intensity represented by the envelope indicated by the first envelope information. Means for changing the intensity of the imaginary part of the spectrum of the interpolation component to be substantially equal to the intensity represented by the envelope indicated by the second envelope information, and supplying the same to the addition unit. And may be provided. In this case, the adding unit may be any unit that generates an output signal representing the sum of the interpolated signal and the interpolation component whose spectrum intensity has been changed. With such a configuration, the signal interpolation device
The components to be added to the interpolated signal, such that the real part of the spectrum is along the envelope of the real part of the spectrum of the interpolated signal, and the imaginary part is along the envelope of the imaginary part of the spectrum of the interpolated signal. Add to interpolated signal. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００１５】前記加算部は、前記補間用成分と実質的に
同相になるように前記被補間信号を遅延させる遅延部を
備え、前記補間用成分及び前記遅延部が遅延させた前記
被補間信号の和を表す前記出力信号を生成するものであ
れば、スペクトル分布生成手段及び補間手段のうちいず
れかが信号の遅延を発生させるものであっても、加算部
が正確に被補間信号の帯域の拡張を行う。The adder includes a delay unit for delaying the interpolated signal so that the interpolated component is substantially in phase with the interpolated component. The adder includes a delay unit for interpolating the interpolated component and the interpolated signal delayed by the delay unit. As long as the output signal representing the sum is generated, even if any one of the spectrum distribution generating means and the interpolating means generates a signal delay, the adding unit can accurately extend the band of the interpolated signal. I do.

【００１６】また、この発明の第２の観点にかかる信号
補間方法は、補間される対象である被補間信号に基づ
き、当該被補間信号が表す値をフーリエ変換して得られ
る複素形式のスペクトルの虚数部及び実数部を表す信号
を生成し、前記スペクトルが占める帯域に含まれる補間
用帯域を特定し、前記スペクトルが実質的に分布しない
被補間帯域を特定し、特定した当該被補間帯域内のスペ
クトルの実数部の分布が前記補間用帯域内のスペクトル
の実数部の分布と実質的に同一であり、特定した当該被
補間帯域内のスペクトルの虚数部の分布が前記補間用帯
域内のスペクトルの虚数部の分布と実質的に同一である
ような補間用成分を生成し、前記被補間信号と前記補間
用成分との和を表す出力信号を生成する、ことを特徴と
する。In a signal interpolation method according to a second aspect of the present invention, based on an interpolated signal to be interpolated, a complex-format spectrum obtained by Fourier-transforming a value represented by the interpolated signal is provided. Generate a signal representing an imaginary part and a real part, specify an interpolation band included in a band occupied by the spectrum, specify an interpolated band in which the spectrum is not substantially distributed, and specify the interpolated band in the specified interpolated band. The distribution of the real part of the spectrum is substantially the same as the distribution of the real part of the spectrum in the interpolation band, and the distribution of the imaginary part of the spectrum in the specified interpolated band is the distribution of the spectrum in the interpolation band. An interpolating component that is substantially the same as the distribution of the imaginary part is generated, and an output signal representing the sum of the interpolated signal and the interpolating component is generated.

【００１７】このような信号補間方法によれば、スペク
トルの実数部及び虚数部の分布が被補間信号のスペクト
ルの一部と実質的に同一であるような成分が被補間信号
に追加され、帯域が拡張される。追加された成分は、被
補間信号の一部分の高調波成分とみなし得るので、被補
間信号が帯域を制限された信号である場合、帯域が拡張
された後の被補間信号は、帯域が制限される前の原信号
に近いものとなる。また、複素形式のスペクトルの実数
部及び虚数部が共に追加されるので、追加された成分の
位相は、帯域の制限により除去された成分の位相に近い
ものとなる。従って、被補間信号がオーディオ信号を表
すものであれば、帯域が拡張された後の被補間信号を用
いてオーディオ信号を復元することにより、オーディオ
信号が低歪み、高音質で復元される。According to such a signal interpolation method, a component whose distribution of the real part and the imaginary part of the spectrum is substantially the same as a part of the spectrum of the signal to be interpolated is added to the signal to be interpolated, Is expanded. Since the added component can be regarded as a harmonic component of a part of the interpolated signal, if the interpolated signal is a band-limited signal, the interpolated signal after the band is extended is band-limited. The original signal is close to the original signal. Also, since both the real part and the imaginary part of the complex spectrum are added, the phase of the added component is close to the phase of the component removed due to band limitation. Therefore, if the interpolated signal represents an audio signal, the audio signal is restored with low distortion and high sound quality by restoring the audio signal using the interpolated signal whose band has been expanded.

【００１８】前記補間用帯域の上限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しいものであれ
ば、被補間信号に追加される成分は、被補間信号の一部
分の高調波成分に特によく近似し得る可能性が高い。従
って、帯域が拡張された後の被補間信号は、帯域が制限
される前の原信号により近いものとなる。If the upper limit of the interpolation band is substantially equal to the upper limit of the spectrum distribution of the signal to be interpolated, the component added to the signal to be interpolated is a harmonic component of a part of the signal to be interpolated. It is highly likely that it can be particularly well approximated. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００１９】前記被補間帯域の下限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しいものであれ
ば、被補間信号に追加される成分のスペクトルは、被補
間信号のスペクトルと、高周波側で隙間なく隣接するも
のとなる。従って、帯域が拡張された後の被補間信号
は、帯域が制限される前の原信号により近いものとな
る。If the lower limit of the interpolated band is substantially equal to the upper limit of the distribution of the spectrum of the interpolated signal, the spectrum of the component added to the interpolated signal includes the spectrum of the interpolated signal and Adjacent without a gap on the high frequency side. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００２０】前記被補間信号のスペクトルの絶対値の包
絡線を表す包絡線情報を抽出し、前記補間用成分のスペ
クトルの強度を、当該補間用成分のスペクトルの絶対値
の強度が前記包絡線情報が示す包絡線により表される強
度に実質的に等しくなるように変更し、前記被補間信号
とスペクトルの強度が変更された前記補間用成分との和
を表す出力信号を生成するようにしてもよい。このよう
な構成を有することにより、被補間信号に追加されるべ
き成分は、そのスペクトルの絶対値が被補間信号のスペ
クトルの包絡線に沿うようにして被補間信号に追加され
る。従って、帯域が拡張された後の被補間信号は、帯域
が制限される前の原信号により近いものとなる。[0020] Envelope information representing the envelope of the absolute value of the spectrum of the signal to be interpolated is extracted, and the intensity of the spectrum of the component for interpolation is determined by the intensity of the absolute value of the spectrum of the component for interpolation. May be changed so as to be substantially equal to the intensity represented by the envelope shown, and an output signal representing the sum of the interpolated signal and the interpolation component whose spectrum intensity has been changed may be generated. Good. With such a configuration, the component to be added to the interpolated signal is added to the interpolated signal such that the absolute value of the spectrum is along the envelope of the spectrum of the interpolated signal. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００２１】前記被補間信号のスペクトルの実数部の包
絡線を表す第１の包絡線情報及び前記被補間信号のスペ
クトルの虚数部の包絡線を表す第２の包絡線情報を抽出
し、前記補間用成分のスペクトルの強度を、当該補間用
成分のスペクトルの実数部の強度が前記第１の包絡線情
報が示す包絡線により表される強度に実質的に等しくな
り、且つ、当該補間用成分のスペクトルの虚数部の強度
が前記第２の包絡線情報が示す包絡線により表される強
度に実質的に等しくなるように変更し、前記被補間信号
とスペクトルの強度が変更された前記補間用成分との和
を表す出力信号を生成するようにしてもよい。こうする
ことにより、被補間信号に追加されるべき成分は、その
スペクトルの実数部が被補間信号のスペクトルの実数部
の包絡線に沿い、虚数部が被補間信号のスペクトルの虚
数部の包絡線に沿うようにして被補間信号に追加され
る。従って、帯域が拡張された後の被補間信号は、帯域
が制限される前の原信号により近いものとなる。The first envelope information representing the envelope of the real part of the spectrum of the signal to be interpolated and the second envelope information representing the envelope of the imaginary part of the spectrum of the signal to be interpolated are extracted. The intensity of the spectrum of the component for interpolation, the intensity of the real part of the spectrum of the component for interpolation is substantially equal to the intensity represented by the envelope indicated by the first envelope information, and The interpolation component in which the intensity of the imaginary part of the spectrum is changed to be substantially equal to the intensity represented by the envelope indicated by the second envelope information, and the interpolated signal and the intensity of the spectrum are changed. May be generated. By doing so, the components to be added to the interpolated signal are such that the real part of the spectrum is along the envelope of the real part of the spectrum of the interpolated signal, and the imaginary part is the envelope of the imaginary part of the spectrum of the interpolated signal. Is added to the signal to be interpolated. Therefore, the signal to be interpolated after the band is extended is closer to the original signal before the band is limited.

【００２２】前記補間用成分と実質的に同相になるよう
に前記被補間信号を遅延させ、前記補間用成分及び遅延
した前記被補間信号の和を表す前記出力信号を生成する
ようにすれば、被補間信号のスペクトルを表す信号を生
成する工程や補間用成分を生成する工程で信号の遅延が
発生する場合も、被補間信号の帯域の拡張が正確に行わ
れる。If the interpolated signal is delayed so as to be substantially in phase with the interpolation component, and the output signal representing the sum of the interpolation component and the delayed interpolated signal is generated. Even when a signal delay occurs in the process of generating a signal representing the spectrum of the signal to be interpolated or in the process of generating the component for interpolation, the band of the signal to be interpolated is accurately extended.

【００２３】また、この発明の第３の観点にかかるコン
ピュータ読み取り可能な記録媒体は、コンピュータを、
補間される対象である被補間信号に基づき、当該被補間
信号が表す値をフーリエ変換して得られる複素形式のス
ペクトルの虚数部及び実数部を表す信号を生成するスペ
クトル分布生成手段と、前記スペクトルが占める帯域に
含まれる補間用帯域を特定する帯域特定手段と、前記ス
ペクトルが実質的に分布しない被補間帯域を特定し、特
定した当該被補間帯域内のスペクトルの実数部の分布
が、前記帯域特定手段により特定された前記補間用帯域
内のスペクトルの実数部の分布と実質的に同一であり、
特定した当該被補間帯域内のスペクトルの虚数部の分布
が、前記帯域特定手段により特定された前記補間用帯域
内のスペクトルの虚数部の分布と実質的に同一であるよ
うな補間用成分を生成する補間手段と、前記被補間信号
と前記補間用成分との和を表す出力信号を生成する加算
部と、して機能させるためのプログラムを記録したこと
を特徴とする。Further, a computer-readable recording medium according to a third aspect of the present invention includes:
A spectrum distribution generating means for generating a signal representing an imaginary part and a real part of a complex form spectrum obtained by Fourier transforming a value represented by the interpolated signal based on the interpolated signal to be interpolated; and Band specifying means for specifying an interpolation band included in the band occupied by, and specifying an interpolated band in which the spectrum is not substantially distributed, and the distribution of the real part of the spectrum in the specified interpolated band is the band. The distribution of the real part of the spectrum in the interpolation band specified by the specifying means is substantially the same,
Generate an interpolation component such that the distribution of the imaginary part of the specified spectrum in the interpolated band is substantially the same as the distribution of the imaginary part of the spectrum in the interpolation band specified by the band specifying unit. And an adder for generating an output signal representing the sum of the signal to be interpolated and the component for interpolation.

【００２４】このような記録媒体に記録されたプログラ
ムを実行するコンピュータは、スペクトルの実数部及び
虚数部の分布が被補間信号のスペクトルの一部と実質的
に同一であるような成分を被補間信号に追加し、帯域を
拡張する。追加された成分は、被補間信号の一部分の高
調波成分とみなし得るので、被補間信号が帯域を制限さ
れた信号である場合、帯域が拡張された後の被補間信号
は、帯域が制限される前の原信号に近いものとなる。ま
た、複素形式のスペクトルの実数部及び虚数部が共に追
加されるので、追加された成分の位相は、帯域の制限に
より除去された成分の位相に近いものとなる。従って、
被補間信号がオーディオ信号を表すものであれば、帯域
が拡張された後の被補間信号を用いてオーディオ信号を
復元することにより、オーディオ信号が低歪み、高音質
で復元される。A computer that executes a program recorded on such a recording medium interpolates components whose distribution of the real part and the imaginary part of the spectrum is substantially the same as a part of the spectrum of the signal to be interpolated. Add to signal and extend bandwidth. Since the added component can be regarded as a harmonic component of a part of the interpolated signal, if the interpolated signal is a band-limited signal, the interpolated signal after the band is extended is band-limited. The original signal is close to the original signal. Also, since both the real part and the imaginary part of the complex spectrum are added, the phase of the added component is close to the phase of the component removed due to band limitation. Therefore,
If the interpolated signal represents an audio signal, the audio signal is restored with low distortion and high sound quality by restoring the audio signal using the interpolated signal whose band has been expanded.

【００２５】[0025]

【発明の実施の形態】以下に、図面を参照して、この発
明の実施の形態に係る信号補間装置を、信号補間器を例
として説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A signal interpolation device according to an embodiment of the present invention will be described below with reference to the drawings, taking a signal interpolator as an example.

【００２６】図１は、この発明の実施の形態に係る信号
補間器の構成を示す図である。図示するように、この信
号補間器は、フーリエ変換部１と、補間バンド解析部３
と、信号補間処理部４と、逆フーリエ変換部５と、補間
バンド加算部６と、遅延部２とより構成されている。FIG. 1 is a diagram showing a configuration of a signal interpolator according to an embodiment of the present invention. As shown, the signal interpolator includes a Fourier transform unit 1 and an interpolation band analysis unit 3
, A signal interpolation processing unit 4, an inverse Fourier transform unit 5, an interpolation band addition unit 6, and a delay unit 2.

【００２７】フーリエ変換部１は、ＤＳＰ（Digital Si
gnal Processor）やＣＰＵ（Central Processing Uni
t）等より構成されている。フーリエ変換部１は、この
信号補間器により補間を受ける対象のＰＣＭ（Pulse Co
de Mudulation）信号が供給される。そして、離散フー
リエ変換あるいは高速フーリエ変換の手法を用い、自己
に供給されたこの信号のスペクトルの離散的な分布を複
素数の集合（具体的には、この複素数の実数部及び虚数
部を表す２個の値からなる組の集合）として表す信号を
生成し、生成した信号を、補間バンド解析部３及び信号
補間処理部４へと供給する。なお、α及びβを実数、ｊ
を虚数単位とした場合、複素数（α＋ｊβ）の実数部は
実数α、虚数部は実数βである。The Fourier transform unit 1 includes a DSP (Digital Si
gnal Processor) and CPU (Central Processing Uni)
t) etc. The Fourier transform unit 1 converts a PCM (Pulse Co.) to be interpolated by the signal interpolator.
de Mudulation) signal. Then, using a discrete Fourier transform or a fast Fourier transform technique, a discrete distribution of the spectrum of the signal supplied to itself is set to a set of complex numbers (specifically, two sets representing a real part and an imaginary part of the complex number). Is generated, and the generated signal is supplied to the interpolation band analysis unit 3 and the signal interpolation processing unit 4. Here, α and β are real numbers, j
Is the imaginary unit, the real part of the complex number (α + jβ) is the real number α, and the imaginary part is the real number β.

【００２８】なお、上述のＰＣＭ信号は、音声等を電圧
あるいは電流の変化として表すオーディオ信号を用いて
ＰＣＭ変調を行うことにより得られる信号である。以下
では、このＰＣＭ信号が表すオーディオ信号のスペクト
ル分布は、元のオーディオ信号のスペクトルのうち１６
キロヘルツ以上の周波数成分が除去されたものに相当す
るものとする。The above-described PCM signal is a signal obtained by performing PCM modulation using an audio signal representing voice or the like as a change in voltage or current. In the following, the spectrum distribution of the audio signal represented by the PCM signal is 16% of the spectrum of the original audio signal.
It is assumed that the frequency component corresponding to the frequency of kilohertz or more is removed.

【００２９】遅延部２は、フーリエ変換部１に供給され
たものと同一のＰＣＭ信号を、フーリエ変換部１と同時
に供給される。そして、自己に供給された入力信号を遅
延させて、補間バンド加算部６に供給する。The delay unit 2 supplies the same PCM signal as that supplied to the Fourier transform unit 1 at the same time as the Fourier transform unit 1. Then, the input signal supplied thereto is delayed and supplied to the interpolation band adder 6.

【００３０】遅延部２が信号を遅延させる時間の長さ
は、フーリエ変換部１に供給された信号の成分が信号補
間処理部４及び逆フーリエ変換部５を経て補間バンド加
算部６に供給されるまでに経過する時間の長さに実質的
に等しいものとする。また、遅延部２から補間バンド加
算部６に供給される遅延された入力信号の位相と、逆フ
ーリエ変換部５から補間バンド加算部６に供給される信
号の位相とは、補間バンド加算部６に同時に供給される
もの同士の間では、実質的に同相であるものとする。The length of time for which the delay unit 2 delays the signal is such that the components of the signal supplied to the Fourier transform unit 1 are supplied to the interpolation band adding unit 6 via the signal interpolation processing unit 4 and the inverse Fourier transform unit 5. To be substantially equal to the length of time that elapses. The phase of the delayed input signal supplied from the delay unit 2 to the interpolation band addition unit 6 and the phase of the signal supplied from the inverse Fourier transform unit 5 to the interpolation band addition unit 6 are the same as those of the interpolation band addition unit 6. Are substantially in phase with each other.

【００３１】補間バンド解析部３は、ＤＳＰやＣＰＵ等
より構成されている。補間バンド解析部３は、スペクト
ルの分布を表す上述の信号をフーリエ変換部１より供給
されると、まず、被補間バンドを特定する。被補間バン
ドは、この信号補間器により補間を受ける対象のＰＣＭ
信号に追加する成分の周波数の上限を上限する連続した
帯域であって、フーリエ変換部１から供給された信号が
表すスペクトルが実質的に含まれていない帯域（具体的
には、例えば、当該スペクトルのうち絶対値が所定値を
超えるスペクトルが含まれていない帯域）である。な
お、複素数（α＋ｊβ）の絶対値は、実数｛（α２＋β
２）１／２｝である。The interpolation band analyzer 3 is composed of a DSP, a CPU and the like. When the above-mentioned signal representing the spectrum distribution is supplied from the Fourier transform unit 1, the interpolation band analysis unit 3 first specifies the band to be interpolated. The band to be interpolated is the PCM to be interpolated by this signal interpolator.
A continuous band that limits the upper limit of the frequency of the component to be added to the signal and that does not substantially include the spectrum represented by the signal supplied from the Fourier transform unit 1 (specifically, for example, the spectrum (A band in which a spectrum whose absolute value exceeds a predetermined value is not included). Note that the absolute value of the complex number (α + jβ) is the real number ｛(α 2 + β
2 ) 1/2 }.

【００３２】次に、補間バンド解析部３は、フーリエ変
換部１から供給された信号が表すスペクトルが占める帯
域の上限を上限とし、帯域幅が、上述の処理で特定され
た被補間バンドの帯域幅に実質的に等しい帯域を、基準
バンドとして特定する。そして、特定した基準バンドの
範囲を指定する情報を、信号補間処理部４へと供給す
る。なお、基準バンドの範囲が指定されれば、被補間バ
ンドの範囲も特定される。Next, the interpolation band analysis unit 3 sets the upper limit of the band occupied by the spectrum represented by the signal supplied from the Fourier transform unit 1 as an upper limit, and determines the bandwidth of the band to be interpolated specified by the above processing. A band substantially equal to the width is specified as a reference band. Then, information specifying the specified reference band range is supplied to the signal interpolation processing unit 4. If the range of the reference band is specified, the range of the band to be interpolated is also specified.

【００３３】信号補間処理部４は、ＤＳＰやＣＰＵ等よ
り構成されている。信号補間処理部４は、スペクトルの
分布を表す上述の信号をフーリエ変換部１より供給され
ると、このスペクトルの絶対値の分布に基づき回帰計算
を行う等して、このスペクトルの絶対値の包絡線をなす
関数を特定する。The signal interpolation processing section 4 comprises a DSP, a CPU and the like. When the above-mentioned signal representing the distribution of the spectrum is supplied from the Fourier transform unit 1, the signal interpolation processing unit 4 performs a regression calculation based on the distribution of the absolute value of the spectrum, and performs an envelope of the absolute value of the spectrum. Identify the functions that make up the line.

【００３４】そして、信号補間処理部４は、補間バンド
解析部３より、基準バンドを特定する情報を供給される
と、特定された基準バンド内のスペクトルを被補間バン
ド内に外挿することにより被補間バンドの補間後のスペ
クトル分布を求める。すなわち、特定された基準バンド
内のスペクトルの周波数を、その元来の値に基準バンド
の最高周波数と最低周波数との差を加算した値へと変更
し、特定した関数の値にこれらのスペクトルの絶対値が
合致するような実数を、これらのスペクトルの複素数の
値に乗じる。そして、信号補間処理部４は、求められた
被補間バンドの補間後のスペクトル分布を表す信号を生
成し、生成した信号を逆フーリエ変換部５へと供給す
る。When the information for specifying the reference band is supplied from the interpolation band analysis unit 3, the signal interpolation processing unit 4 extrapolates the spectrum in the specified reference band into the band to be interpolated. The spectrum distribution of the band to be interpolated is obtained. That is, the frequency of the spectrum in the specified reference band is changed to a value obtained by adding the difference between the highest frequency and the lowest frequency of the reference band to its original value, and the value of these spectra is changed to the value of the specified function. The real numbers whose absolute values match are multiplied by the complex values of these spectra. Then, the signal interpolation processing unit 4 generates a signal representing the obtained spectrum distribution of the interpolated band after interpolation, and supplies the generated signal to the inverse Fourier transform unit 5.

【００３５】逆フーリエ変換部５は、ＤＳＰやＣＰＵ等
より構成されており、上述の通り、信号補間処理部４が
出力する、被補間バンドの補間後のスペクトル分布を表
す信号を供給される。そして、離散逆フーリエ変換ある
いは高速逆フーリエ変換の手法を用い、自己に供給され
た信号が表すスペクトル分布を有するＰＣＭ信号を生成
して、補間バンド加算部６に供給する。The inverse Fourier transform unit 5 is composed of a DSP, a CPU and the like, and is supplied with the signal output from the signal interpolation processing unit 4 and representing the interpolated spectrum distribution of the band to be interpolated, as described above. Then, using a method of discrete inverse Fourier transform or fast inverse Fourier transform, a PCM signal having a spectrum distribution represented by the signal supplied thereto is generated and supplied to the interpolation band adder 6.

【００３６】補間バンド加算部６は、ＤＳＰやＣＰＵ等
より構成されており、遅延部２から自己に供給される遅
延されたＰＣＭ信号の値と逆フーリエ変換部５から供給
されるＰＣＭ信号の値との和を表すＰＣＭ信号を生成
し、この信号補間器の出力信号として出力する。The interpolation band adder 6 is composed of a DSP, a CPU, etc., and has a value of the delayed PCM signal supplied from the delay unit 2 to itself and a value of the PCM signal supplied from the inverse Fourier transform unit 5. And generates a PCM signal representing the sum of the signals and outputs the signal as an output signal of the signal interpolator.

【００３７】従って、この信号補間器の出力信号のスペ
クトル（補間後のスペクトル）は、元のＰＣＭ信号のス
ペクトルに被補間バンドの補間後のスペクトルが加算さ
れて得られるスペクトルに実質的に等しいものとなる。Therefore, the spectrum of the output signal of this signal interpolator (the spectrum after interpolation) is substantially equal to the spectrum obtained by adding the spectrum after interpolation of the band to be interpolated to the spectrum of the original PCM signal. Becomes

【００３８】なお、図２（ａ）は、補間前のスペクトル
の実数部の分布の一例を示す図であり、図２（ｂ）は、
補間前のスペクトルの虚数部の分布の一例を示す図であ
る。なお、図２（ａ）及び（ｂ）は、同一のＰＣＭ信号
のスペクトルを表している。図示するように、このＰＣ
Ｍ信号は、１６キロヘルツ以上の周波数成分を実質的に
含んでいない。FIG. 2A shows an example of the distribution of the real part of the spectrum before interpolation, and FIG.
It is a figure showing an example of distribution of an imaginary part of a spectrum before interpolation. FIGS. 2A and 2B show the spectra of the same PCM signal. As shown, this PC
The M signal does not substantially include a frequency component of 16 kHz or more.

【００３９】また、図２（ｃ）は、図２（ａ）及び
（ｂ）に示すスペクトルのうちから特定された基準バン
ドのスペクトルの実数部の分布を示す図であり、図２
（ｄ）は、図２（ａ）及び（ｂ）に示すスペクトルのう
ちから特定された基準バンドのスペクトルの虚数部の分
布を示す図である。なお、図２（ａ）及び（ｂ）にスペ
クトルを示すＰＣＭ信号に追加する成分の周波数の上限
は、２０キロヘルツであるものとする。図示するよう
に、このＰＣＭ信号に追加する成分の周波数の上限が２
０キロヘルツであって、このＰＣＭ信号が１６キロヘル
ツ以上の周波数成分を実質的に含んでいないときは、１
６キロヘルツ以上２０キロヘルツ以下の帯域が被補間バ
ンドとして特定され、１２キロヘルツ以上１６キロヘル
ツ未満の帯域が、基準バンドとして特定される。FIG. 2 (c) is a diagram showing the distribution of the real part of the spectrum of the reference band specified from the spectra shown in FIGS. 2 (a) and 2 (b).
(D) is a diagram showing the distribution of the imaginary part of the spectrum of the reference band specified from the spectra shown in FIGS. 2 (a) and (b). The upper limit of the frequency of the component added to the PCM signal whose spectrum is shown in FIGS. 2A and 2B is assumed to be 20 kHz. As shown, the upper limit of the frequency of the component added to the PCM signal is 2
0 kHz, and when the PCM signal does not substantially include a frequency component of 16 kHz or more, 1
A band between 6 kHz and 20 kHz is specified as a band to be interpolated, and a band between 12 kHz and 16 kHz is specified as a reference band.

【００４０】また、図２（ｅ）は、図２（ａ）及び
（ｂ）にスペクトルを示すＰＣＭ信号を補間して得られ
るＰＣＭ信号のスペクトル（補間後のスペクトル）の実
数部の分布の一例を示す図であり、図２（ｆ）は、補間
後のスペクトルの虚数部の分布の一例を示す図である。
図示するように、補間後のスペクトルの実数部の分布
は、図２（ａ）に示す分布と図２（ｃ）に示す分布とを
加算したものに相当する。また、補間後のスペクトルの
虚数部の分布は、図２（ｂ）に示す分布と図２（ｄ）に
示す分布とを加算したものに相当する。FIG. 2E shows an example of the distribution of the real part of the spectrum (interpolated spectrum) of the PCM signal obtained by interpolating the PCM signal whose spectrum is shown in FIGS. 2A and 2B. FIG. 2 (f) is a diagram showing an example of the distribution of the imaginary part of the spectrum after interpolation.
As shown, the distribution of the real part of the spectrum after interpolation corresponds to the sum of the distribution shown in FIG. 2A and the distribution shown in FIG. 2C. The distribution of the imaginary part of the spectrum after interpolation corresponds to the sum of the distribution shown in FIG. 2B and the distribution shown in FIG. 2D.

【００４１】補間後のスペクトル分布のうち補間バンド
加算部６により加算された被補間バンドの部分のスペク
トル分布は、補間前のスペクトルが占める帯域の上限を
上限とする連続した帯域である基準バンドのスペクトル
分布に相当するので、被補間バンドの部分は、この基準
バンドの高調波成分とみなし得る。また、被補間バンド
の複素形式のスペクトルの実数部及び虚数部が共に補間
前のスペクトルに追加されるので、追加された被補間バ
ンドの位相は、帯域の制限により除去されたオーディオ
信号の成分の位相に近いものとなる。従って、この信号
補間器が出力する出力信号は、帯域が制限される前のオ
ーディオ信号に近いオーディオ信号をＰＣＭ変調して得
られるＰＣＭ信号となり、この出力信号を用いてオーデ
ィオ信号を復元することにより、オーディオ信号が高音
質で復元される。The spectrum distribution of the interpolated band added by the interpolation band adder 6 in the spectrum distribution after interpolation is a continuous band of a reference band whose upper limit is the upper limit of the band occupied by the spectrum before interpolation. Since this corresponds to the spectral distribution, the portion of the band to be interpolated can be regarded as a harmonic component of this reference band. Also, since both the real part and the imaginary part of the complex form spectrum of the interpolated band are added to the spectrum before interpolation, the phase of the added interpolated band is the phase of the component of the audio signal removed by the band limitation. It is close to the phase. Therefore, the output signal output from the signal interpolator is a PCM signal obtained by performing PCM modulation on an audio signal close to the audio signal before the band is limited, and the audio signal is restored by using this output signal. Thus, the audio signal is restored with high sound quality.

【００４２】なお、この信号補間器の構成は上述のもの
に限られない。例えば、信号補間処理部４は、スペクト
ルの分布を表す上述の信号をフーリエ変換部１より供給
されると、このスペクトルの実数部及び虚数部の分布に
つき回帰計算を行う等して、このスペクトルの実数部及
び虚数部の包絡線をなす２個の関数を特定してもよい。The configuration of the signal interpolator is not limited to the above. For example, when the above-mentioned signal representing the distribution of the spectrum is supplied from the Fourier transform unit 1, the signal interpolation processing unit 4 performs a regression calculation on the distribution of the real part and the imaginary part of the spectrum, and performs the regression calculation. Two functions forming the envelope of the real part and the imaginary part may be specified.

【００４３】この場合、信号補間処理部４は、補間バン
ド解析部３が特定した基準バンド内のスペクトルの実数
部の値を、スペクトルの実数部の包絡線をなす関数の値
に合致するよう被補間バンド内に外挿し、基準バンド内
のスペクトルの虚数部の値を、スペクトルの虚数部の包
絡線をなす関数の値に合致するよう被補間バンド内に外
挿するものとする。この結果得られる、被補間バンドの
補間後のスペクトルの実数部の分布と、被補間バンドの
補間後のスペクトルの虚数部の分布とが、被補間バンド
の補間後のスペクトルの分布を表す。In this case, the signal interpolation processing unit 4 converts the value of the real part of the spectrum in the reference band specified by the interpolation band analysis unit 3 so as to match the value of the function forming the envelope of the real part of the spectrum. It is assumed that the value of the imaginary part of the spectrum in the reference band is extrapolated to the value of the function forming the envelope of the imaginary part of the spectrum. The distribution of the real part of the spectrum after interpolation of the band to be interpolated and the distribution of the imaginary part of the spectrum after interpolation of the band to be interpolated represent the distribution of the spectrum of the band to be interpolated after interpolation.

【００４４】また、基準バンドの上限は、必ずしも補間
前のスペクトルが占める帯域の上限と実質的に一致して
いなくてもよい。ただし、基準バンドの上限が補間前の
スペクトルが占める帯域の上限に一致するようにすれ
ば、基準バンドの最高周波数は元のＰＣＭ信号のスペク
トルの最高周波数を含んでいるので、基準バンド内のス
ペクトル自体が、補間前のスペクトルの一部分の高調波
成分とみなし得る可能性が高い。従って、基準バンドの
上限が補間前のスペクトルが占める帯域の上限に一致し
ていれば、一致していない場合に比べ、帯域が制限され
る前のオーディオ信号により近いオーディオ信号を表す
ものとなる。The upper limit of the reference band does not necessarily have to substantially coincide with the upper limit of the band occupied by the spectrum before interpolation. However, if the upper limit of the reference band matches the upper limit of the band occupied by the spectrum before interpolation, the highest frequency of the reference band includes the highest frequency of the spectrum of the original PCM signal. There is a high possibility that the signal itself can be regarded as a harmonic component of a part of the spectrum before interpolation. Therefore, if the upper limit of the reference band coincides with the upper limit of the band occupied by the spectrum before interpolation, the signal represents an audio signal closer to the audio signal before the band is limited than in the case where the upper limit does not match.

【００４５】また、この信号補間器が補間を行う対象の
信号はＰＣＭ信号である必要はなく、オーディオ信号を
変調して得られる変調波である必要もない。また、信号
補間処理部４は、必ずしもフーリエ変換部１から供給さ
れた信号が表すスペクトルの包絡線を特定しなくてもよ
く、補間後の被補間バンド内のスペクトルの強度を変更
しなくてもよい。The signal to be interpolated by the signal interpolator does not need to be a PCM signal, and need not be a modulated wave obtained by modulating an audio signal. Further, the signal interpolation processing unit 4 does not necessarily need to specify the envelope of the spectrum represented by the signal supplied from the Fourier transform unit 1, and does not need to change the intensity of the spectrum in the interpolated band after interpolation. Good.

【００４６】以上、この発明の実施の形態を説明した
が、この発明にかかる信号補間装置は、専用のシステム
によらず、通常のコンピュータシステムを用いて実現可
能である。例えば、パーソナルコンピュータやマイクロ
コンピュータに上述のフーリエ変換部１、遅延部２、補
間バンド解析部３、信号補間処理部４、逆フーリエ変換
部５及び補間バンド加算部６の動作を実行するためのプ
ログラムを格納した媒体（ＣＤ−ＲＯＭ、ＭＯ、フロッ
ピー（登録商標）ディスク等）から該プログラムをイン
ストールすることにより、上述の処理を実行する信号補
間器を構成することができる。Although the embodiments of the present invention have been described above, the signal interpolating apparatus according to the present invention can be realized using a general computer system without using a dedicated system. For example, a program for executing the operations of the above-described Fourier transform unit 1, delay unit 2, interpolation band analysis unit 3, signal interpolation processing unit 4, inverse Fourier transform unit 5, and interpolation band addition unit 6 in a personal computer or a microcomputer. By installing the program from a medium (CD-ROM, MO, floppy (registered trademark) disk, or the like) storing the above, a signal interpolator that executes the above-described processing can be configured.

【００４７】また、例えば、通信回線の掲示板（ＢＢ
Ｓ）に該プログラムを掲示し、これを通信回線を介して
配信してもよく、また、該プログラムを表す信号により
搬送波を変調し、得られた変調波を伝送し、この変調波
を受信した装置が変調波を復調して該プログラムを復元
するようにしてもよい。そして、このプログラムを起動
し、ＯＳの制御下に、他のアプリケーションプログラム
と同様に実行することにより、上述の処理を実行するこ
とができる。Further, for example, a bulletin board (BB) of a communication line
The program may be posted on S) and distributed via a communication line. Alternatively, the carrier wave is modulated by a signal representing the program, the obtained modulated wave is transmitted, and the modulated wave is received. The device may demodulate the modulated wave to restore the program. Then, by starting this program and executing it in the same manner as other application programs under the control of the OS, the above-described processing can be executed.

【００４８】なお、ＯＳが処理の一部を分担する場合、
あるいは、ＯＳが本願発明の１つの構成要素の一部を構
成するような場合には、記録媒体には、その部分をのぞ
いたプログラムを格納してもよい。この場合も、この発
明では、その記録媒体には、コンピュータが実行する各
機能又はステップを実行するためのプログラムが格納さ
れているものとする。When the OS shares a part of the processing,
Alternatively, when the OS constitutes a part of one component of the present invention, a program excluding the part may be stored in the recording medium. 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.

【００４９】[0049]

【発明の効果】以上の説明のように、この発明によれ
ば、原信号の帯域を制限した信号を用いて得られる変調
波から原信号に近い信号を復元できるようにするための
信号補間装置及び信号補間方法が実現される。また、こ
の発明によれば、オーディオ信号を高音質で復元するた
めの信号補間装置及び信号補間方法が実現される。As described above, according to the present invention, a signal interpolation apparatus for restoring a signal close to the original signal from a modulated wave obtained by using a signal whose band of the original signal is limited. And a signal interpolation method. Further, according to the present invention, a signal interpolation device and a signal interpolation method for restoring an audio signal with high sound quality are realized.

【図面の簡単な説明】[Brief description of the drawings]

【図１】この発明の実施の形態に係る信号補間器の構成
を示す図である。FIG. 1 is a diagram showing a configuration of a signal interpolator according to an embodiment of the present invention.

【図２】（ａ）は、補間前のスペクトルの実数部の分布
の一例を示す図であり、（ｂ）は、補間前のスペクトル
の虚数部の分布の一例を示す図であり、（ｃ）は、基準
バンドのスペクトルの実数部の分布を示す図であり、
（ｄ）は、基準バンドのスペクトルの虚数部の分布を示
す図であり、（ｅ）は補間後のスペクトルの実数部の分
布の一例を示す図であり、（ｆ）は、補間後のスペクト
ルの虚数部の分布の一例を示す図である。2A is a diagram illustrating an example of a distribution of a real part of a spectrum before interpolation, FIG. 2B is a diagram illustrating an example of a distribution of an imaginary part of the spectrum before interpolation, and FIG. ) Shows the distribution of the real part of the spectrum of the reference band,
(D) is a diagram showing the distribution of the imaginary part of the spectrum of the reference band, (e) is a diagram showing an example of the distribution of the real part of the spectrum after interpolation, and (f) is the spectrum after interpolation. FIG. 6 is a diagram showing an example of the distribution of the imaginary part of the above.

【符号の説明】[Explanation of symbols]

１ フーリエ変換部 ２ 遅延部 ３ 補間バンド解析部 ４ 信号補間処理部 ５ 逆フーリエ変換部 ６ 補間バンド加算部 DESCRIPTION OF SYMBOLS 1 Fourier transformation part 2 Delay part 3 Interpolation band analysis part 4 Signal interpolation processing part 5 Inverse Fourier transformation part 6 Interpolation band addition part

Claims (13)

【特許請求の範囲】[Claims] 【請求項１】補間される対象である被補間信号に基づ
き、当該被補間信号が表す値をフーリエ変換して得られ
る複素形式のスペクトルの虚数部及び実数部を表す信号
を生成するスペクトル分布生成手段と、 前記スペクトルが占める帯域に含まれる補間用帯域を特
定する帯域特定手段と、 前記スペクトルが実質的に分布しない被補間帯域を特定
し、特定した当該被補間帯域内のスペクトルの実数部の
分布が、前記帯域特定手段により特定された前記補間用
帯域内のスペクトルの実数部の分布と実質的に同一であ
り、特定した当該被補間帯域内のスペクトルの虚数部の
分布が、前記帯域特定手段により特定された前記補間用
帯域内のスペクトルの虚数部の分布と実質的に同一であ
るような補間用成分を生成する補間手段と、 前記被補間信号と前記補間用成分との和を表す出力信号
を生成する加算部と、を備える、 ことを特徴とする信号補間装置。1. A spectrum distribution generator for generating a signal representing an imaginary part and a real part of a complex spectrum obtained by Fourier transforming a value represented by the interpolated signal based on the interpolated signal to be interpolated. Means, a band specifying means for specifying an interpolation band included in the band occupied by the spectrum, and specifying the interpolated band in which the spectrum is not substantially distributed, the real part of the spectrum in the specified interpolated band The distribution is substantially the same as the distribution of the real part of the spectrum in the interpolation band specified by the band specifying unit, and the distribution of the imaginary part of the spectrum in the specified band to be interpolated is the band identification. Interpolating means for generating an interpolation component that is substantially the same as the distribution of the imaginary part of the spectrum in the interpolation band specified by the means; It comprises an addition unit for generating an output signal representing the sum of the interpolation components, a signal interpolation apparatus, characterized in that. 【請求項２】前記補間用帯域の上限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しい、 ことを特徴とする請求項１に記載の信号補間装置。2. The signal interpolation apparatus according to claim 1, wherein an upper limit of the interpolation band is substantially equal to an upper limit of a spectrum distribution of the interpolated signal. 【請求項３】前記被補間帯域の下限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しい、 ことを特徴とする請求項１又は２に記載の信号補間装
置。3. The signal interpolation apparatus according to claim 1, wherein a lower limit of the interpolated band is substantially equal to an upper limit of a spectrum distribution of the interpolated signal. 【請求項４】前記補間手段は、 前記被補間信号のスペクトルの絶対値の包絡線を表す包
絡線情報を抽出する手段と、 前記補間用成分のスペクトルの強度を、当該補間用成分
のスペクトルの絶対値の強度が前記包絡線情報が示す包
絡線により表される強度に実質的に等しくなるように変
更して前記加算部に供給する手段と、を備え、 前記加算部は、前記被補間信号とスペクトルの強度が変
更された前記補間用成分との和を表す出力信号を生成す
るものである、ことを特徴とする請求項１、２又は３に
記載の信号補間装置。4. The interpolation means: means for extracting envelope information representing an envelope of the absolute value of the spectrum of the signal to be interpolated; and the intensity of the spectrum of the interpolation component Means for changing the intensity of the absolute value so as to be substantially equal to the intensity represented by the envelope indicated by the envelope information and supplying the absolute value to the addition unit, wherein the addition unit includes 4. The signal interpolation apparatus according to claim 1, wherein an output signal is generated that represents a sum of the interpolation component whose spectrum intensity has been changed. 【請求項５】前記補間手段は、 前記被補間信号のスペクトルの実数部の包絡線を表す第
１の包絡線情報及び前記被補間信号のスペクトルの虚数
部の包絡線を表す第２の包絡線情報を抽出する手段と、 前記補間用成分のスペクトルの強度を、当該補間用成分
のスペクトルの実数部の強度が前記第１の包絡線情報が
示す包絡線により表される強度に実質的に等しくなり、
且つ、当該補間用成分のスペクトルの虚数部の強度が前
記第２の包絡線情報が示す包絡線により表される強度に
実質的に等しくなるように変更して前記加算部に供給す
る手段と、を備え、 前記加算部は、前記被補間信号とスペクトルの強度が変
更された前記補間用成分との和を表す出力信号を生成す
るものである、ことを特徴とする請求項１、２又は３に
記載の信号補間装置。5. The interpolation means comprises: first envelope information representing an envelope of a real part of the spectrum of the signal to be interpolated; and a second envelope representing an envelope of an imaginary part of the spectrum of the signal to be interpolated. Means for extracting information, the intensity of the spectrum of the interpolation component, the intensity of the real part of the spectrum of the interpolation component being substantially equal to the intensity represented by the envelope indicated by the first envelope information. Become
A means for changing the intensity of the imaginary part of the spectrum of the interpolation component to be substantially equal to the intensity represented by the envelope indicated by the second envelope information and supplying the intensity to the adding unit; And wherein the addition section generates an output signal representing a sum of the signal to be interpolated and the interpolation component whose spectrum intensity has been changed. 3. The signal interpolation device according to 1. 【請求項６】前記加算部は、前記補間用成分と実質的に
同相になるように前記被補間信号を遅延させる遅延部を
備え、前記補間用成分及び前記遅延部が遅延させた前記
被補間信号の和を表す前記出力信号を生成する、 ことを特徴とする請求項１乃至５のいずれか１項に記載
の信号補間装置。6. The interpolator further includes a delay unit for delaying the interpolated signal so that the interpolated component is substantially in phase with the interpolated component, and the interpolated component and the interpolated delay delayed by the delay unit. The signal interpolation apparatus according to any one of claims 1 to 5, wherein the output signal representing a sum of the signals is generated. 【請求項７】補間される対象である被補間信号に基づ
き、当該被補間信号が表す値をフーリエ変換して得られ
る複素形式のスペクトルの虚数部及び実数部を表す信号
を生成し、 前記スペクトルが占める帯域に含まれる補間用帯域を特
定し、 前記スペクトルが実質的に分布しない被補間帯域を特定
し、特定した当該被補間帯域内のスペクトルの実数部の
分布が前記補間用帯域内のスペクトルの実数部の分布と
実質的に同一であり、特定した当該被補間帯域内のスペ
クトルの虚数部の分布が前記補間用帯域内のスペクトル
の虚数部の分布と実質的に同一であるような補間用成分
を生成し、 前記被補間信号と前記補間用成分との和を表す出力信号
を生成する、ことを特徴とする信号補間方法。7. A signal representing an imaginary part and a real part of a complex-form spectrum obtained by performing a Fourier transform on a value represented by the interpolated signal based on the interpolated signal to be interpolated; Specifying the interpolation band included in the band occupied by, specifying the interpolated band in which the spectrum is not substantially distributed, and the distribution of the real part of the specified spectrum in the interpolated band is the spectrum in the interpolating band. Interpolation such that the distribution of the imaginary part of the spectrum in the specified interpolated band is substantially the same as the distribution of the imaginary part of the spectrum in the interpolation band. A signal interpolation method comprising: generating an interpolation component; and generating an output signal representing a sum of the interpolation target signal and the interpolation component. 【請求項８】前記補間用帯域の上限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しい、 ことを特徴とする請求項７に記載の信号補間方法。8. The signal interpolation method according to claim 7, wherein an upper limit of the interpolation band is substantially equal to an upper limit of a spectrum distribution of the interpolated signal. 【請求項９】前記被補間帯域の下限は、前記被補間信号
のスペクトルの分布の上限に実質的に等しい、 ことを特徴とする請求項７又は８に記載の信号補間方
法。9. The signal interpolation method according to claim 7, wherein a lower limit of the interpolated band is substantially equal to an upper limit of a spectrum distribution of the interpolated signal. 【請求項１０】前記被補間信号のスペクトルの絶対値の
包絡線を表す包絡線情報を抽出し、 前記補間用成分のスペクトルの強度を、当該補間用成分
のスペクトルの絶対値の強度が前記包絡線情報が示す包
絡線により表される強度に実質的に等しくなるように変
更し、 前記被補間信号とスペクトルの強度が変更された前記補
間用成分との和を表す出力信号を生成する、 ことを特徴とする請求項７、８又は９に記載の信号補間
方法。10. An envelope information representing an envelope of an absolute value of a spectrum of the signal to be interpolated is extracted, and the intensity of the spectrum of the component for interpolation is determined by the intensity of the absolute value of the spectrum of the component for interpolation. Generating an output signal representing the sum of the interpolated signal and the interpolated component whose spectrum intensity has been changed, so as to be substantially equal to the intensity represented by the envelope indicated by the line information; The signal interpolation method according to claim 7, 8 or 9, wherein 【請求項１１】前記被補間信号のスペクトルの実数部の
包絡線を表す第１の包絡線情報及び前記被補間信号のス
ペクトルの虚数部の包絡線を表す第２の包絡線情報を抽
出し、 前記補間用成分のスペクトルの強度を、当該補間用成分
のスペクトルの実数部の強度が前記第１の包絡線情報が
示す包絡線により表される強度に実質的に等しくなり、
且つ、当該補間用成分のスペクトルの虚数部の強度が前
記第２の包絡線情報が示す包絡線により表される強度に
実質的に等しくなるように変更し、 前記被補間信号とスペクトルの強度が変更された前記補
間用成分との和を表す出力信号を生成する、 ことを特徴とする請求項７、８又は９に記載の信号補間
方法。11. Extracting first envelope information representing the envelope of the real part of the spectrum of the interpolated signal and second envelope information representing the envelope of the imaginary part of the spectrum of the interpolated signal; The intensity of the spectrum of the interpolation component, the intensity of the real part of the spectrum of the interpolation component is substantially equal to the intensity represented by the envelope indicated by the first envelope information,
And the intensity of the imaginary part of the spectrum of the interpolation component is changed to be substantially equal to the intensity represented by the envelope indicated by the second envelope information, and the intensity of the signal to be interpolated and the intensity of the spectrum are changed. The signal interpolation method according to claim 7, 8 or 9, wherein an output signal representing a sum of the changed interpolation component and the interpolation component is generated. 【請求項１２】前記補間用成分と実質的に同相になるよ
うに前記被補間信号を遅延させ、前記補間用成分及び遅
延した前記被補間信号の和を表す前記出力信号を生成す
る、 ことを特徴とする請求項７乃至１１のいずれか１項に記
載の信号補間方法。12. The method according to claim 1, wherein the interpolated signal is delayed so as to be substantially in phase with the interpolation component, and the output signal representing the sum of the interpolation component and the delayed interpolated signal is generated. The signal interpolation method according to any one of claims 7 to 11, wherein: 【請求項１３】コンピュータを、 補間される対象である被補間信号に基づき、当該被補間
信号が表す値をフーリエ変換して得られる複素形式のス
ペクトルの虚数部及び実数部を表す信号を生成するスペ
クトル分布生成手段と、 前記スペクトルが占める帯域に含まれる補間用帯域を特
定する帯域特定手段と、 前記スペクトルが実質的に分布しない被補間帯域を特定
し、特定した当該被補間帯域内のスペクトルの実数部の
分布が、前記帯域特定手段により特定された前記補間用
帯域内のスペクトルの実数部の分布と実質的に同一であ
り、特定した当該被補間帯域内のスペクトルの虚数部の
分布が、前記帯域特定手段により特定された前記補間用
帯域内のスペクトルの虚数部の分布と実質的に同一であ
るような補間用成分を生成する補間手段と、 前記被補間信号と前記補間用成分との和を表す出力信号
を生成する加算部と、 して機能させるためのプログラムを記録したコンピュー
タ読み取り可能な記録媒体。13. A computer, based on an interpolated signal to be interpolated, generates a signal representing an imaginary part and a real part of a complex spectrum obtained by Fourier transforming a value represented by the interpolated signal. A spectrum distribution generating unit, a band specifying unit that specifies an interpolation band included in a band occupied by the spectrum, and a band to be interpolated in which the spectrum is not substantially distributed. The distribution of the real part is substantially the same as the distribution of the real part of the spectrum in the interpolation band specified by the band specifying means, and the distribution of the imaginary part of the spectrum in the specified band to be interpolated is Interpolation means for generating an interpolation component that is substantially the same as the distribution of the imaginary part of the spectrum in the interpolation band specified by the band identification means, An adder that generates an output signal representing a sum of the interpolated signal and the interpolation component; and a computer-readable recording medium storing a program for causing the signal to function.
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