EP1405302B1 - Method for masking interference during the transfer of digital audio signals - Google Patents

Method for masking interference during the transfer of digital audio signals Download PDF

Info

Publication number
EP1405302B1
EP1405302B1 EP02740252A EP02740252A EP1405302B1 EP 1405302 B1 EP1405302 B1 EP 1405302B1 EP 02740252 A EP02740252 A EP 02740252A EP 02740252 A EP02740252 A EP 02740252A EP 1405302 B1 EP1405302 B1 EP 1405302B1
Authority
EP
European Patent Office
Prior art keywords
signal
audio signal
audio
digital
data error
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.)
Expired - Lifetime
Application number
EP02740252A
Other languages
German (de)
French (fr)
Other versions
EP1405302A1 (en
Inventor
Claus Kupferschmidt
Gerd Penshorn
Arnd Wendland
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1405302A1 publication Critical patent/EP1405302A1/en
Application granted granted Critical
Publication of EP1405302B1 publication Critical patent/EP1405302B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G10MUSICAL INSTRUMENTS; ACOUSTICS
    • G10LSPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/005Correction of errors induced by the transmission channel, if related to the coding algorithm

Definitions

  • the invention is based on a method for concealing Disturbances in a signal derived from a digital signal, reproduced audio signal according to the genus of independent patent claim.
  • analog FM radio receiver In case of analog. Systems are decreasing Reception quality to a gradual deterioration of Quality of the audio signal contained in the broadcast signal, the For example, analog FM radio receiver with a Stereo / mono switching or muting of the encounter the audio signal to be reproduced.
  • Patent Abstracts of Japan to JP-A-10-308708 discloses an arrangement for receiving and for reproducing digitally transmitted audio information transmitted via a Error detection and correction has, whereby in the case of an undisturbed or disturbed, however correctable received signal reproduces the audio signals contained therein while in the case of a significantly disturbed receive signal section means a noise signal generator using the received signal, a noise signal is generated and added to the audio information to be reproduced is added.
  • the inventive method with the features of the independent claim has the advantage that the listener a reliable Assessment basis for the currently selected playback volume for a is transmitted by means of a digital Ruadfunksignals transmitted Andiosignal.
  • the listener a reliable Assessment basis for the currently selected playback volume for a is transmitted by means of a digital Ruadfunksignals transmitted Andiosignal.
  • the user disadvantageously increases the volume. additionally is the perceived as unpleasant effect of bit errors within the received digital broadcasting signal in the form of Gurgelns within the reproduced Audio signal reduced.
  • the invention proposes that in a method of occlusion of noise in a reproduced audio signal resulting from a digital signal is derived, wherein the reproduced audio signal in dependence of a Data error statistics of the digital signal is attenuated, the attenuated Audio signal depending on the data error statistics of the digital signal Replacement signal is superimposed.
  • the reproduced Audio signal depending on the data error statistics of the digital signal is frequency selectively attenuated, and that the replacement signal is frequency-selectively superimposed.
  • the reproduction quality of a received analogue Broadcast signal usually a so-called high-cut, d. H. a reduction of high frequency fractions of the to be reproduced audio signal.
  • a particularly good basis for estimating the actually set volume of the digital Radio receiver is given by the fact that the Superimposition of the substitute signal the attenuation of the Audio signal due to a high data error rate completely compensated, so that the volume of the overlay the attenuated audio signal and the substitute signal formed Retroaudiosignals the one undisturbed received or reproduced audio signal corresponds.
  • the substitute signal can advantageously be in the form of a Noise signal, a sine or a note or a stored or synthesized speech signal formed be. Especially in the case of a noise signal as Replacement signal can continue this advantageously in terms of its frequency response to the psychoacoustic Be adapted to the characteristics of the human ear.
  • the replacement signal can be attenuated Audio signal either in the time domain or in the frequency domain be superimposed additively.
  • the inventive method is characterized in Advantageously characterized by the fact that it basically all audio formats or all digitally transmitted Audio signals, in particular digital broadcast signals various standards, such as DAB, DSR or similar, equally applicable.
  • the process is particularly simple feasible, since the control of both the degree of Attenuation of the reproduced audio signal, as well as the Measurement of the superposition of the substitute signal in direct Dependence of one by means of a data error statistics detectable data error rate of the received digital Broadcast signal is controllable.
  • the inventive method in no way on the Source decoding of the audio data from the received digital broadcasting signals, so that the process without affecting the decoded audio signal as well can be switched off.
  • an audio decoder MPEG 1, 2 Layer 2 with integrated bit or data error concealment shown in Figure 1, an audio decoder MPEG 1, 2 Layer 2 with integrated bit or data error concealment shown.
  • MPEG designates one from the Fraunhofer-Gesellschaft developed method for coding or Compression of digital audio data.
  • the named Audio decoder thus serves the decoding of the MPEG format present digital audio data.
  • the MPEG encoded digital audio signal 101 which is at a Data input 10 of the arrangement pending is a decoder 11th fed.
  • the decoder 11 the decoding of the coded digital audio signal and an error detection and optionally correcting the received data signal.
  • the pending at a first output of the decoder 11 Audio signal 111 is a filter circuit 12, the for example in the form of an equalizer, but optionally also in the form of a bandpass filter with adjustable Cutoff frequencies, edge steepness and Total amplification factor can be formed, fed.
  • the audio signal 121 evaluated by the filter 12 is an overlay circuit 13 in the present case in the form an adder 13 is supplied.
  • the one Circuit arrangement 16 for generating an error statistic is supplied.
  • a data error rate of at the input 10 of the circuit 1 pending digital error signal indicating error signal 161 removable is supplied.
  • This is an assignment circuit 17 fed in the function of the error statistics signal 161 Parameters for controlling the equalizer 12 or the Filters 12 are selected. For example, in case an approximately undisturbed signal at the data input 10 the equalizer 12 and the filter 12 via a Filter control signal 171 controlled such that this supplied decoded audio signal 111 substantially unchanged at the output of the equalizer or filter 12 is removable.
  • the assignment circuit 17 is also a from the Error Statistics Generation 16 Generated Bit Error Signal 162 fed, which is the bit error of the digital input signal represents.
  • the bit error signal 162 is from the internal Checks for frame header or the data error itself is derived and is a direct measure of the current Error rate.
  • the error statistics signal 161 due to a low-pass characteristic on error in digital signal comparatively slow-reacting Signal.
  • selected data set 171 for Control of the equalizer 12 and the filter 12 is this supplied from the assignment circuit 17. Furthermore, it is a record 172 inverse to the selected record 171 Filter parameters supplied to a replacement signal generator 18, furthermore, according to the mentioned preferred embodiment of the invention, the bit error signal 162 from the Error statistics generation 16 is supplied.
  • the spare signal generator 18 generates depending on him supplied second equalizer or filter parameters 172, according to the preferred embodiment of the invention above in addition to the bit error signal 162, a shaped according to these parameters Spare signal, which is a second input of the Overlay circuit 13 is supplied.
  • the the replacement signal generation 18 supplied Filter parameter set 172 is according to a preferred Embodiment of the invention designed such that the filter curves of the filter 12 and the evaluation of the Replacement signal provided in the spare signal generation 18 second filter compensate each other, so that in the sum gives a linear frequency response.
  • the filter curves for example, Figure 2 too see where the amplitude frequency response 125 of the filter 12th and the further amplitude frequency response 185 of the evaluation the replacement signal in the spare signal generation 18 provided second filter over the frequency 200th are applied.
  • the one certain degree of error or a certain Data error rate of the input signal is assigned by a maximum value with a 3dB cutoff frequency 210 closes down to the value 0.
  • a maximum frequency 220 a Audio signal playback anyway for the human ear is not noticeable, the further falls Amplitude frequency response 185 to this maximum frequency 220 out to the value 0.
  • the replacement signal generator 18 is according to a preferred Embodiment of the invention designed such that in this generates a neutral noise signal as a substitute signal becomes.
  • a total audio signal 141 which consists of a Superimposition of one according to the measured data error rate attenuated audio signal and also according to the Data error rate generated noise signal consists.
  • the proportion of the Audio signal 121 increases at the expense of the noise signal 181
  • the Audio signal 121 increasingly through the noise signal 181st replaced.
  • the substitute signal in the form of a or a superposition of several sine or Knowledge is formed.
  • the replacement signal is a stored or is synthesized speech signal. It can continue Replacement signal 181 also in the form of a to the physiology of adapted to human hearing and filtered accordingly Be carried out noise.
  • the present method is basically any kind of digitally coded audio signals applicable. So it is within the scope of the present invention, that the data input 10 any digitally coded Audio signal 101 can be fed.
  • the decoder is then on the particular type of digitally encoded audio signal 101 adapted or adapted so that at the output of a correctly decoded audio signal 111 is removable.
  • the invention is also in the time domain present audio signals applicable, in this case then the back transformation 14 accounts, further then Filter 12, decoding 16, assignment circuit 17 and Replacement signal generation 18 adapted accordingly.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computational Linguistics (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Noise Elimination (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)
  • Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
  • Circuit For Audible Band Transducer (AREA)

Description

Stand der TechnikState of the art

Die Erfindung geht von einem Verfahren zur Verdeckung von Störungen in einem aus einem digitalen Signal abgeleiteten, wiedergegebenen Audiosignal nach der Gattung des unabhängigen Patentanspruchs aus.The invention is based on a method for concealing Disturbances in a signal derived from a digital signal, reproduced audio signal according to the genus of independent patent claim.

In Systemen der digitalen Übertragungstechnik in der mobilen Kommunikation kommt es infolge nicht idealer Übertragungskanäle, insbesondere durch Mehrwegeempfang, Reflexionen, Abschattungen sowie Dämpfungen, zu Störungen im digitalen Übertragungssignal, die sich in Form von Bitfehlern auswirken. Diese können senderseitig durch eine geeignete Kanalcodierung oder durch eine empfängerseitige geeignete Decodierung in gewissem Umfang korrigiert werden. Steigt die Datenfehlerrate innerhalb des digitalen Übertragungssignals über einen vorgegebenen Wert an, ist eine Korrektur der Bitfehler nicht mehr möglich, so dass sich diese auf die mit dem digitalen Übertragungssignal übertragenen Dateninhalte, beispielsweise im Falle eines digital übertragenen Hörrundfunksignals auf ein wiederzugebendes Audiosignal, in Form deutlich wahrnehmbarer Störungen auswirken. In systems of digital transmission technology in the mobile Communication comes as a result of not ideal Transmission channels, in particular by multipath reception, Reflections, shadowing and damping, disturbances in the digital transmission signal, which is in the form of Affect bit errors. These can on the transmitter side by a suitable channel coding or by a receiver side appropriate decoding be corrected to some extent. Increases the data error rate within the digital Transmission signal over a predetermined value, is a correction of bit errors is no longer possible, so that These are the ones with the digital transmission signal transmitted data content, for example in the case of a digitally transmitted audio broadcasting signal on to be reproduced audio signal, in the form clearly perceptible Interference.

Im Falle analoger. Systeme kommt es bei abnehmender Empfangsqualität zu einer graduellen Verschlechterung der Qualität des im Rundfunksignal enthaltenen Audiosignals, dem beispielsweise analoge FM-Rundfunkempfänger mit einer Stereo-/Mono-Umschaltung bzw. Stummschaltung des wiederzugebenden Audiosignals begegnen.In case of analog. Systems are decreasing Reception quality to a gradual deterioration of Quality of the audio signal contained in the broadcast signal, the For example, analog FM radio receiver with a Stereo / mono switching or muting of the encounter the audio signal to be reproduced.

Bei digitalen Systemen gibt es eine derartige graduelle oder schleichende Verschlechterung des Signals in Abhängigkeit der Störung des Übertragungssignals nicht. Vielmehr bewegt sich die Qualität digital übertragener Audiosignale im Bereich entweder einer sehr guten oder einer sehr schlechten Qualität. Um einen gleitenden Übergang von guter zu schlechter Qualität im Falle digitaler Systeme zu realisieren, bedient man sich bei diesen einer Nachbildung dieses Verfahrens (Graceful Degradation). Die zur Verschleierung von Fehlern dort zum Einsatz kommenden Verfahren neigen wiederum im Falle einer hohen Datenfehlerrate dazu, das Signal leiser bzw. vollkommen stumm zu stellen. Dies kann bei dauerhafter Stummschaltung infolge dauerhaft hoher Datenfehlerrate des Übertragungssignals zur Verwirrung des Benutzers führen, dem suggeriert wird, dass der Rundfunkempfänger nur ein sehr leises oder überhaupt kein Audiosignal wiedergibt. Dies kann den Benutzer dazu veranlassen, den Lautstärkepegel zur Wiedergabe des Audiosignals über den Lautstärkesteller zu erhöhen. Darüber hinaus wird das durch Bitfehler hervorgerufene sogenannte Gurgeln innerhalb des wiedergegebenen Audiosignals in der Regel als sehr unangenehm empfunden. Wird nun das digitale Rundfunksignal nach durch den Benutzer initiierter Lautstärkeerhöhung wieder mit.ausreichender Qualität, also mit einer Datenfehlerrate, die eine Korrektur der Datenfehler ermöglicht, empfangen, wird die infolge der Empfangsverschlechterung zuvor abgeschwächte oder stummgeschaltete Audiowiedergabe schlagartig wieder aufgenommen, was nach Erhöhung der Wiedergabelautstärke zu einer Schädigung der angeschlossenen Lautsprecher und möglicherweise auch des Gehörs des Benutzers führen kann.In digital systems there is such a gradual or creeping deterioration of the signal depending on the disturbance of the transmission signal is not. Rather moved the quality of digitally transmitted audio signals in the Range of either a very good or a very bad one Quality. To make a smooth transition from good to poor quality in the case of digital systems too Realize, one uses in these a replica this process (Graceful Degradation). The to Obfuscation of errors coming in use there In turn, methods tend to be high in case of high Data error rate to the signal quieter or perfect to mute. This can be done with permanent mute due to permanently high data error rate of the Transmission signal lead to confusion of the user, the it is suggested that the radio receiver is only a very soft or no audio signal at all. This can prompt the user to adjust the volume level Playback of the audio signal via the volume control increase. In addition, this is due to bit errors caused so-called gargles within the played back audio signal as a rule uncomfortable. Will now be the digital broadcast signal after user-initiated volume increase again with.sufficient quality, so with one Data error rate, which is a correction of data errors allows to receive, which is due to the Reception deterioration previously attenuated or muted Audio playback abruptly resumed, which after increasing the Playback volume to damage the connected speakers and may also result in the user's hearing.

Patent Abstracts of Japan zu JP-A-10-308708 offenbart einer Anordnung zum Empfang und zur Wiedergabe digital fibertragener Audioinformationen, die über eine Fehlererkennung und -korrektur verfügt, wobei im Falle eines ungestörten oder gestörten, jedoch korrigierbaren Empfangsignals die darin enthaltenen Audiosignale wiedergegeben werden, während im Falle eines erheblich gestörten Empfangssignalabschnitts mittels eines Rauschsignalgenerators unter Verwendung des Empfangssignals ein Rauschsignal erzeugt und den wiederzugebenden Audioinformationen additiv überlagert wird.Patent Abstracts of Japan to JP-A-10-308708 discloses an arrangement for receiving and for reproducing digitally transmitted audio information transmitted via a Error detection and correction has, whereby in the case of an undisturbed or disturbed, however correctable received signal reproduces the audio signals contained therein while in the case of a significantly disturbed receive signal section means a noise signal generator using the received signal, a noise signal is generated and added to the audio information to be reproduced is added.

Vorteile der ErfindungAdvantages of the invention

Das erfindungsgemäße Verfahren mit den Merkmalen des unabhängigen Patentanspruchs hat demgegenüber den Vorteil, dass dem Zuhörer eine zuverlässige Beurteihungsgrundlage für die momentan vorgewählte Wiedergabelautstärke für ein mittels eines digitalen Ruadfunksignals übertragenes Andiosignal vermittett wird. Damit wird die Gefahr vermieden, dass während einer Abschwächung bzw. der Audiowiedergabe infolge hoher Datenfehlerrate des empfangenen digitalen Rundfunksignals der Benutzer unvorteilhafterweise die Lautstärke erhöht. Zusätzlich wird die als unangenehm empfundene Wirkung der Bitfehler innerhalb des empfangenen digitalen Rundfunksignals in Form des Gurgelns innerhalb des wiedergegebenen Audiosignals reduziert.The inventive method with the features of the independent claim has the advantage that the listener a reliable Assessment basis for the currently selected playback volume for a is transmitted by means of a digital Ruadfunksignals transmitted Andiosignal. In order to avoids the risk that during a mitigation or the Audio playback due to high data error rate of the received digital Broadcast signal the user disadvantageously increases the volume. additionally is the perceived as unpleasant effect of bit errors within the received digital broadcasting signal in the form of Gurgelns within the reproduced Audio signal reduced.

Dazu wird erfindungsgemäß vorgeschlagen, dass bei einem Verfahren zur Verdeckung von Störungen in einem wiedergegebenen Audiosignal, das aus einem digitalen Signal abgeleitet wird, wobei das wiedergegebene Audiosignal in Abhängigkeit einer Datenfehlerstatistik des digitalen Signals abgeschwächt wird, dem abgeschwächten Audiosignal in Abhängigkeit der Datenfehlerstatistik des digitalen Signals ein Ersatzsignal überlagert wird.For this purpose, the invention proposes that in a method of occlusion of noise in a reproduced audio signal resulting from a digital signal is derived, wherein the reproduced audio signal in dependence of a Data error statistics of the digital signal is attenuated, the attenuated Audio signal depending on the data error statistics of the digital signal Replacement signal is superimposed.

Es ist dabei von besonderem Vorteil, dass das wiedergegebene Audiosignal in Abhängigkeit der Datenfehlerstatistik des digitalen Signals frequenzselektiv abgeschwächt wird, und dass das Ersatzsignal frequenzselektiv überlagert wird. Auf diese Weise ist eine weitere Annäherung des Verhaltens eines digitalen Rundfunkempfängers an das eines analogen, insbesondere FM-Rundfunkempfängers angleichbar. So führen analoge FM-Rundfunkempfänger infolge einer Verschlechterung der Empfangsqualität eines empfangenen analogen Rundfunksignals in der Regel einen sogenannten High-Cut, d. h. eine Absenkung hochfrequenter Anteile des wiederzugebenden Audiosignals durch.It is of particular advantage that the reproduced Audio signal depending on the data error statistics of the digital signal is frequency selectively attenuated, and that the replacement signal is frequency-selectively superimposed. On this way is another approach of one's behavior digital radio receiver to that of an analog, in particular FM radio receiver equalizable. To lead analog FM radio receiver due to deterioration the reception quality of a received analogue Broadcast signal usually a so-called high-cut, d. H. a reduction of high frequency fractions of the to be reproduced audio signal.

Aufgrund der Tatsache, daß Audiosignale im Bereich niedriger Frequenzen eher von tonalen Komponenten geprägt sind und höhere Frequenzbereiche sich eher durch rauschartige Signalanteile auszeichnen, führt die Substitution höherer Frequenzbereiche durch Ersatzrauschen zu einer besseren Signalqualität und damit besserem Hörempfinden nach dem Error-Concealment.Due to the fact that audio signals in the range lower Frequencies are more characterized by tonal components and higher frequency ranges are more likely to be noise-like Signal components, the substitution leads to higher Frequency ranges through replacement noise to a better Signal quality and thus better hearing after the Error Concealment.

Auch werden durch die frequenzselektive Signalabschwächung und -substitution durch Bitfehler verursachte zwitschernde Störungen im Audiosignal, sogenannte Birdies, reduziert, so daß sich die subjektive Wahrnehmung des Audiosignals verbessert.Also, by the frequency-selective signal attenuation and -substitution caused by bit errors chirping Disturbances in the audio signal, so-called birdies, reduced, so that the subjective perception of the audio signal improved.

Eine besonders gute Abschätzungsgrundlage für die tatsächlich eingestellte Lautstärke des digitalen Rundfunkempfängers wird dadurch gegeben, dass die Überlagerung des Ersatzsignals die Abschwächung des Audiosignals infolge einer hohen Datenfehlerrate vollständig kompensiert, so dass die Lautstärke des aus der Überlagerung des abgeschwächten Audiosignals und des Ersatzsignals gebildeten Gesamtaudiosignals der eines ungestört empfangenen bzw. wiedergegebenen Audiosignals entspricht. A particularly good basis for estimating the actually set volume of the digital Radio receiver is given by the fact that the Superimposition of the substitute signal the attenuation of the Audio signal due to a high data error rate completely compensated, so that the volume of the overlay the attenuated audio signal and the substitute signal formed Gesamtaudiosignals the one undisturbed received or reproduced audio signal corresponds.

Das Ersatzsignal kann vorteilhafterweise in Form eines Rauschsignals, eines Sinus- oder Kenntons oder eines gespeicherten oder synthetisierten Sprachsignals gebildet sein. Insbesondere im Falle eines Rauschsignals als Ersatzsignal kann dieses weiterhin vorteilhafterweise hinsichtlich seines Frequenzgangs an die psychoakustischen Eigenschaften des menschlichen Gehörs angepaßt sein.The substitute signal can advantageously be in the form of a Noise signal, a sine or a note or a stored or synthesized speech signal formed be. Especially in the case of a noise signal as Replacement signal can continue this advantageously in terms of its frequency response to the psychoacoustic Be adapted to the characteristics of the human ear.

Weiterhin kann das Ersatzsignal dem abgeschwächten Audiosignal entweder im Zeitbereich oder im Frequenzbereich additiv überlagert werden.Furthermore, the replacement signal can be attenuated Audio signal either in the time domain or in the frequency domain be superimposed additively.

Das erfindungsgemäße Verfahren zeichnet sich in vorteilhafter Weise dadurch aus, dass es grundsätzlich auf alle Audioformate bzw. alle in digitaler Form übertragene Audiosignale, insbesondere digitale Rundfunksignale verschiedener Standards, wie beispielsweise DAB, DSR oder ähnliche, gleichermaßen anwendbar ist.The inventive method is characterized in Advantageously characterized by the fact that it basically all audio formats or all digitally transmitted Audio signals, in particular digital broadcast signals various standards, such as DAB, DSR or similar, equally applicable.

Darüber hinaus ist das Verfahren besonders einfach realisierbar, da die Steuerung sowohl des Maßes der Abschwächung des wiedergegebenen Audiosignals, als auch des Maßes der Überlagerung des Ersatzsignals in direkter Abhängigkeit einer mittels einer Datenfehlerstatistik erfaßbaren Datenfehlerrate des empfangenen digitalen Rundfunksignals steuerbar ist.In addition, the process is particularly simple feasible, since the control of both the degree of Attenuation of the reproduced audio signal, as well as the Measurement of the superposition of the substitute signal in direct Dependence of one by means of a data error statistics detectable data error rate of the received digital Broadcast signal is controllable.

Darüber hinaus ist es von besonderem Vorteil, dass das erfindungsgemäße Verfahren sich in keiner Weise auf die Quellendecodierung der Audiodaten aus den empfangenen digitalen Rundfunksignalen auswirkt, so dass das Verfahren ohne Beeinflussung des decodierten Audiosignals auch abschaltbar ist. In addition, it is of particular advantage that the inventive method in no way on the Source decoding of the audio data from the received digital broadcasting signals, so that the process without affecting the decoded audio signal as well can be switched off.

Zeichnungendrawings

Ein vorteilhaftes Ausführungsbeispiel der Erfindung ist in den Figuren dargestellt und nachfolgend näher erläutert.

  • Figur 1 zeigt ein Blockschaltbild einer Anordnung 1 zur Durchführung des erfindungsgemäßen Verfahrens am Beispiel eines MPEG-Audiodecoders mit integriertem sogenanntem Error-Concealment, bei dem ein Ersatzsignal dem bedarfsweise abgeschwächten Audiosignal im Frequenzbereich überlagert wird.
  • Figur 2 zeigt die Überlagerung von Audiosignal und Ersatzsignal im Frequenzbereich.
  • An advantageous embodiment of the invention is illustrated in the figures and explained in more detail below.
  • 1 shows a block diagram of an arrangement 1 for carrying out the method according to the invention using the example of an MPEG audio decoder with integrated so-called error concealment, in which a substitute signal is superimposed on the as-needed attenuated audio signal in the frequency domain.
  • FIG. 2 shows the superimposition of the audio signal and the substitute signal in the frequency domain.
  • Beschreibung der AusführungsbeispieleDescription of the embodiments

    In Figur 1 ist ein Audiodecoder MPEG 1, 2 Layer 2 mit integrierter Bit- bzw. Datenfehlerverschleierung dargestellt. MPEG bezeichnet dabei ein von der Fraunhofer-Gesellschaft entwickeltes Verfahren zur Codierung bzw. Komprimierung digitaler Audiodaten. Der genannte Audiodecoder dient somit der Decodierung der im MPEG-Format vorliegenden digitalen Audiodaten.In Figure 1, an audio decoder MPEG 1, 2 Layer 2 with integrated bit or data error concealment shown. MPEG designates one from the Fraunhofer-Gesellschaft developed method for coding or Compression of digital audio data. The named Audio decoder thus serves the decoding of the MPEG format present digital audio data.

    Das MPEG-codierte digitale Audiosignal 101, das an einem Dateneingang 10 der Anordnung ansteht, ist einem Decoder 11 zugeführt. Im Decoder 11 erfolgt die Decodierung des codierten digitalen Audiosignals sowie eine Fehlererkennung und gegebenenfalls -korrektur des empfangenen Datensignals. Das an einem ersten Ausgang des Decoders 11 anstehende Audiosignal 111 ist einer Filterschaltung 12, die beispielsweise in Form eines Equalizers, wahlweise aber auch in Form eines Bandpassfilters mit einstellbaren Grenzfrequenzen, Flankensteilheit und Gesamtverstärkungsfaktor ausgebildet sein kann, zugeführt. Das mittels des Filters 12 bewertete Audiosignal 121 ist einer Überlagerungsschaltung 13 im vorliegenden Fall in Form eines Addiergliedes 13 zugeführt. Das am Ausgang des Addiergliedes 13 abnehmbare Gesamtaudiosignal 131 wird in einem inversen Filter 14 vom Frequenz- in den Zeitbereich rücktransformiert, so dass am Ausgang 15 der Schaltungsanordnung 1 das über die Lautsprecher einer die Schaltungsanordnung 1 enthaltenden Audioanlage wiedergebbare Gesamtaudiosignal 141 ansteht.The MPEG encoded digital audio signal 101, which is at a Data input 10 of the arrangement pending is a decoder 11th fed. In the decoder 11, the decoding of the coded digital audio signal and an error detection and optionally correcting the received data signal. The pending at a first output of the decoder 11 Audio signal 111 is a filter circuit 12, the for example in the form of an equalizer, but optionally also in the form of a bandpass filter with adjustable Cutoff frequencies, edge steepness and Total amplification factor can be formed, fed. The audio signal 121 evaluated by the filter 12 is an overlay circuit 13 in the present case in the form an adder 13 is supplied. That at the exit of the Adder 13 removable total audio signal 131 is in an inverse filter 14 from the frequency to the time domain transformed back, so that at the output 15 of the Circuit arrangement 1 via the speakers of a Circuit arrangement 1 containing audio system reproducible Total audio signal 141 is pending.

    Die Notwendigkeit einer Rücktransformation 14 ergibt sich aus der Tatsache, daß MPEG-codierte Signale im Frequenzbereich vorliegen, jeder Abtastwert des Audiosignals liegt somit in Form dessen Spektral verteilung vor.The need for inverse transformation 14 results from the fact that MPEG coded signals in the Frequency range, each sample of the audio signal is thus in the form of its spectral distribution.

    An einem zweiten Ausgang des Decoders 11 ist ein die Datenfehlerrate des empfangenen digitalen Signals repräsentierendes Fehlersignal 112 abnehmbar, das einer Schaltungsanordnung 16 zur Erzeugung einer Fehlerstatistik zugeführt ist. An einem ersten Ausgang der Fehlerstatistikerzeugung 16 ist ein die Datenfehlerrate des am Eingang 10 der Schaltungsanordnung 1 anstehenden digitalen Signals anzeigendes Fehlerstatistiksignal 161 abnehmbar. Dieses ist einer Zuordnungsschaltung 17 zugeführt, in der in Abhängigkeit des Fehlerstatistiksignals 161 Parameter zur Steuerung des Equalizers 12 bzw. des Filters 12 ausgewählt werden. Beispielsweise wird im Falle eines näherungsweise ungestörten Signals am Dateneingang 10 der Equalizer 12 bzw. das Filter 12 über ein Filtersteuersignal 171 derart gesteuert, dass das diesem zugeführte decodierte Audiosignal 111 im wesentlichen unverändert am Ausgang des Equalizers bzw. Filters 12 abnehmbar ist. Demgegenüber wird bei zunehmender Datenfehlerrate in der Zuordnungsschaltung 17 ein Parametersatz zur Steuerung des Equalizers 12 bzw. Filters 12 dergestalt ausgewählt, dass zunächst höherfrequente Anteile des Audiosignals 111, mit weiter zunehmender Datenfehlerrate zunehmend auch niederfrequente Anteile des Audiosignals 111 und schließlich das gesamte Audiosignal abgeschwächt wird.At a second output of the decoder 11 is a Data error rate of the received digital signal Detecting error signal 112 removable, the one Circuit arrangement 16 for generating an error statistic is supplied. At a first exit of the Error Statistics Generation 16 is a data error rate of at the input 10 of the circuit 1 pending digital error signal indicating error signal 161 removable. This is an assignment circuit 17 fed in the function of the error statistics signal 161 Parameters for controlling the equalizer 12 or the Filters 12 are selected. For example, in case an approximately undisturbed signal at the data input 10 the equalizer 12 and the filter 12 via a Filter control signal 171 controlled such that this supplied decoded audio signal 111 substantially unchanged at the output of the equalizer or filter 12 is removable. In contrast, with increasing Data error rate in the assignment circuit 17 a Parameter set for controlling the equalizer 12 or filter 12 selected such that initially higher-frequency Proportions of the audio signal 111, with further increasing Data error rate increasingly also low - frequency components of the Audio signal 111 and finally the entire audio signal is weakened.

    Gemäß einer bevorzugten Ausführungsform der Erfindung ist der Zuordnungsschaltung 17 weiterhin ein ebenfalls von der Fehlerstatistikerzeugung 16 generiertes Bitfehlersignal 162 zugeführt, das die Bitfehler des digitalen Eingangssignals repräsentiert. Das Bitfehlersignal 162 wird aus den internen Prüfungen für Rahmenheader oder der Datenfehler selbst abgeleitet und ist ein direktes Maß für die aktuelle Fehlerrate. Demgegenüber ist das Fehlerstatistiksignal 161 aufgrund einer Tiefpaßcharakteristik ein auf Fehler im digitalen Signal vergleichsweise langsam reagierendes Signal.According to a preferred embodiment of the invention the assignment circuit 17 is also a from the Error Statistics Generation 16 Generated Bit Error Signal 162 fed, which is the bit error of the digital input signal represents. The bit error signal 162 is from the internal Checks for frame header or the data error itself is derived and is a direct measure of the current Error rate. In contrast, the error statistics signal 161 due to a low-pass characteristic on error in digital signal comparatively slow-reacting Signal.

    Eine in Abhängigkeit der Datenfehlerrate bzw. des die Datenfehlerrate repräsentierenden Fehlerstatistiksignals 161, gemäß einer bevorzugten Ausführungsform zusätzlich des Bitfehlersignals 162, ausgewählter Datensatz 171 zur Steuerung des Equalizers 12 bzw. des Filters 12 ist diesem von der Zuordnungsschaltung 17 zugeführt. Des weiteren ist ein dem gewählten Datensatz 171 inverser Datensatz 172 an Filterparametern einem Ersatzsignalgenerator 18 zugeführt, dem weiterhin, gemäß erwähnter bevorzugter Ausführungsform der Erfindung, das Bitfehlersignal 162 von der Fehlerstatistikerzeugung 16 zugeführt ist.One depending on the data error rate or the Data error rate representing error statistics signal 161, according to a preferred embodiment additionally of Bit error signal 162, selected data set 171 for Control of the equalizer 12 and the filter 12 is this supplied from the assignment circuit 17. Furthermore, it is a record 172 inverse to the selected record 171 Filter parameters supplied to a replacement signal generator 18, furthermore, according to the mentioned preferred embodiment of the invention, the bit error signal 162 from the Error statistics generation 16 is supplied.

    Der Ersatzsignalgenerator 18 erzeugt in Abhängigkeit der ihm zugeführten zweiten Equalizer- bzw. Filterparameter 172, gemäß der bevorzugten Ausführungsform der Erfindung darüber hinaus in zusätzlicher Abhängigkeit des Bitfehlersignals 162, ein entsprechend diesen Parametern geformtes Ersatzsignal, das einem zweiten Eingang der Überlagerungsschaltung 13 zugeführt ist. Somit ist am Ausgang der Überlagerungsschaltung 13 ein Gesamtaudiosignal 131 abnehmbar, das aus einer Überlagerung, im vorliegendem Fall einer Addition, des nach Maßgabe der ersten Equalizer- bzw. Filterparameter 171 mittels des Equalizers oder Filters 12 abgeschwächten Audiosignals und eines nach Maßgabe der zweiten Equalizer- bzw. Filterparameter 172 geformten Ersatzsignals 181 besteht.The spare signal generator 18 generates depending on him supplied second equalizer or filter parameters 172, according to the preferred embodiment of the invention above in addition to the bit error signal 162, a shaped according to these parameters Spare signal, which is a second input of the Overlay circuit 13 is supplied. Thus, on Output of the superposition circuit 13 a total audio signal 131 removable, that from an overlay, in the present Case of an addition, which is subject to the first equalizer or filter parameter 171 by means of the equalizer or filter 12 attenuated audio signal and one in accordance with the second equalizer or filter parameters 172 shaped Substitute signal 181 exists.

    Der der Ersatzsignalgenerierung 18 zugeführte Filterparametersatz 172 ist gemäss einer bevorzugten Ausführungsform der Erfindung derart ausgelegt, dass sich die Filterkurven des Filters 12 und des zur Bewertung des Ersatzsignals in der Ersatzsignalgenerierung 18 vorgesehenen zweiten Filters gegenseitig kompensieren, so dass sich in der Summe ein linearer Frequenzgang ergibt. Dieser Verlauf der Filterkurven ist beispielsweise auch Figur 2 zu entnehmen, wo der Amplitudenfrequenzgang 125 des Filters 12 und der weitere Amplitudenfrequenzgang 185 des zur Bewertung des Ersatzsignals in der Ersatzsignalgenerierung 18 vorgesehenen zweiten Filters über der Frequenz 200 aufgetragen sind. Wie der Figur zu entnehmen, nimmt der Amplitudenfrequenzgang 125 des Filters bzw. Equalizers 12, der einem bestimmten Fehlergrad bzw. einer bestimmten Datenfehlerrate des Eingangssignals zugeordnet ist, von einem Maximalwert mit einer 3dB-Grenzfrequenz 210 schließt sich auf den Wert 0 ab. Demgegenüber nimmt der derselben Datenfehlerrate bzw. Datenfehlerstatistik zugeordnete weitere Frequenzgang 185 vom Wert 0 über die 3dB-Grenzfrequenz 210 auf einen Wert zu, der der maximalen Amplitude des Amplitudenfrequenzgangs 125 entspricht. Da oberhalb einer Maximalfrequenz 220 eine Audiosignalwiedergabe ohnehin für das menschliche Gehör nicht wahrnehmbar ist, fällt der weitere Amplitudenfrequenzgang 185 zu dieser Maximalfrequenz 220 hin auf den Wert 0 ab.The the replacement signal generation 18 supplied Filter parameter set 172 is according to a preferred Embodiment of the invention designed such that the filter curves of the filter 12 and the evaluation of the Replacement signal provided in the spare signal generation 18 second filter compensate each other, so that in the sum gives a linear frequency response. This course the filter curves, for example, Figure 2 too see where the amplitude frequency response 125 of the filter 12th and the further amplitude frequency response 185 of the evaluation the replacement signal in the spare signal generation 18 provided second filter over the frequency 200th are applied. As the figure shows, takes the Amplitude frequency response 125 of the filter or equalizer 12, the one certain degree of error or a certain Data error rate of the input signal is assigned by a maximum value with a 3dB cutoff frequency 210 closes down to the value 0. In contrast, he takes the same Data error rate or data error statistics assigned another frequency response 185 of the value 0 over the 3dB cutoff frequency 210 to a value that is the maximum Amplitude of the amplitude frequency response 125 corresponds. There above a maximum frequency 220 a Audio signal playback anyway for the human ear is not noticeable, the further falls Amplitude frequency response 185 to this maximum frequency 220 out to the value 0.

    Wie Figur 2 zu entnehmen, überlagern sich die beiden Frequenzgänge 125 und 185 des Filters 12 bzw. der Ersatzsignalerzeugung 18 zu einem insgesamt linearen und konstanten Frequenzgang.As can be seen from FIG. 2, the two overlap Frequency responses 125 and 185 of the filter 12 and the Replacement signal generation 18 to a total of linear and constant frequency response.

    Der Ersatzsignalgenerator 18 ist gemäss einer bevorzugten Ausführungsform der Erfindung derart ausgelegt, dass in diesem ein neutrales Rauschsignal als Ersatzsignal erzeugt wird. Somit ergibt sich am Ausgang 15 der Schaltung 1 der Figur 1 ein Gesamtaudiosignal 141, das aus einer Überlagerung eines gemäss der gemessenen Datenfehlerrate abgeschwächten Audiosignals und eines ebenfalls gemäss der Datenfehlerrate erzeugten Rauschsignals besteht. Zu niedrigeren Datenfehlerraten hin wird der Anteil des Audiosignals 121 auf Kosten des Rauschsignals 181 zunehmen, demgegenüber wird im Falle zunehmender Datenfehlerrate das Audiosignal 121 zunehmend durch das Rauschsignal 181 ersetzt.The replacement signal generator 18 is according to a preferred Embodiment of the invention designed such that in this generates a neutral noise signal as a substitute signal becomes. Thus arises at the output 15 of the circuit 1 of Figure 1 shows a total audio signal 141, which consists of a Superimposition of one according to the measured data error rate attenuated audio signal and also according to the Data error rate generated noise signal consists. To lower data error rates, the proportion of the Audio signal 121 increases at the expense of the noise signal 181, In contrast, in the case of increasing data error rate is the Audio signal 121 increasingly through the noise signal 181st replaced.

    Gemäss einer vorteilhafter Weiterbildungen der Erfindung kann es demgegenüber vorgesehen sein, dass das Ersatzsignal in Form eines oder einer überlagerung mehrerer Sinus- oder Kenntöne ausgebildet ist. Des weiteren kann es vorgesehen sein, dass das Ersatzsignal ein gespeichertes oder synthetisiertes Sprachsignal ist. Weiter kann das Ersatzsignal 181 auch in Form eines an die Physiologie des menschlichen Gehörs angepassten und entsprechend gefilterten Rauschens ausgeführt sein.According to an advantageous developments of the invention In contrast, it may be provided that the substitute signal in the form of a or a superposition of several sine or Knowledge is formed. Furthermore it can be provided be that the replacement signal is a stored or is synthesized speech signal. It can continue Replacement signal 181 also in the form of a to the physiology of adapted to human hearing and filtered accordingly Be carried out noise.

    Wie eingangs erwähnt, ist das vorliegende Verfahren grundsätzlich auf jedwede Art digital codierter Audiosignale anwendbar. So liegt es im Bereich vorliegender Erfindung, dass dem Dateneingang 10 ein beliebiges digital codiertes Audiosignal 101 zuführbar ist. Der Decodierer ist dann an die jeweilige Art des digital codierten Audiosignals 101 angepasst bzw. anzupassen, so dass an dessen Ausgang ein korrekt decodiertes Audiosignal 111 abnehmbar ist.As mentioned above, the present method is basically any kind of digitally coded audio signals applicable. So it is within the scope of the present invention, that the data input 10 any digitally coded Audio signal 101 can be fed. The decoder is then on the particular type of digitally encoded audio signal 101 adapted or adapted so that at the output of a correctly decoded audio signal 111 is removable.

    Grundsätzlich ist die Erfindung auch auf im Zeitbereich vorliegende Audiosignale anwendbar, für diesen Fall kann dann die Rücktransformation 14 entfallen, weiters sind dann Filter 12, Decodierung 16, Zuordnungsschaltung 17 und Ersatzsignalgenerierung 18 entsprechend angepasst.In principle, the invention is also in the time domain present audio signals applicable, in this case then the back transformation 14 accounts, further then Filter 12, decoding 16, assignment circuit 17 and Replacement signal generation 18 adapted accordingly.

    Claims (3)

    1. Method for masking interference in a reproduced audio signal which is derived from a digital signal,
      where the reproduced audio signal is attenuated on the basis of a data error statistic for the digital signal,
      the audio signal being overlaid with a substitute signal on the basis of the data error statistic for the digital signal,
      characterized in that the reproduced audio signal is attenuated at selected frequencies on the basis of the data error statistic for the digital signal, and
      in that the substitute signal is overlaid at selected frequencies.
    2. Method according to Claim 1, characterized in that the overlaying of the substitute signal compensates for the attenuation of the audio signal.
    3. Method according to one of the preceding claims, characterized in that the substitute signal is formed by a noise signal, a sinusoidal or characteristic tone or by a voice signal.
    EP02740252A 2001-06-22 2002-04-12 Method for masking interference during the transfer of digital audio signals Expired - Lifetime EP1405302B1 (en)

    Applications Claiming Priority (3)

    Application Number Priority Date Filing Date Title
    DE10130233 2001-06-22
    DE10130233A DE10130233A1 (en) 2001-06-22 2001-06-22 Interference masking method for digital audio signal transmission
    PCT/DE2002/001368 WO2003001509A1 (en) 2001-06-22 2002-04-12 Method for masking interference during the transfer of digital audio signals

    Publications (2)

    Publication Number Publication Date
    EP1405302A1 EP1405302A1 (en) 2004-04-07
    EP1405302B1 true EP1405302B1 (en) 2004-12-15

    Family

    ID=7689138

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP02740252A Expired - Lifetime EP1405302B1 (en) 2001-06-22 2002-04-12 Method for masking interference during the transfer of digital audio signals

    Country Status (6)

    Country Link
    US (1) US20040221209A1 (en)
    EP (1) EP1405302B1 (en)
    JP (1) JP4221288B2 (en)
    DE (2) DE10130233A1 (en)
    ES (1) ES2233828T3 (en)
    WO (1) WO2003001509A1 (en)

    Families Citing this family (8)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    KR100708123B1 (en) * 2005-02-04 2007-04-16 삼성전자주식회사 Method and apparatus for controlling audio volume automatically
    EP1941496B1 (en) * 2005-09-01 2009-12-09 Telefonaktiebolaget LM Ericsson (publ) Processing encoded real-time data
    US8620644B2 (en) 2005-10-26 2013-12-31 Qualcomm Incorporated Encoder-assisted frame loss concealment techniques for audio coding
    DE102006034625A1 (en) * 2006-07-27 2008-01-31 Bayerische Motoren Werke Ag Sound releasing method for mobile radio device, involves releasing audible spare signal on output device in case of low quality of radio signal received by receiver unit
    JP2013031151A (en) 2011-06-20 2013-02-07 Renesas Electronics Corp Encryption communication system and encryption communication method
    PL3367380T3 (en) 2014-06-13 2020-06-29 Telefonaktiebolaget Lm Ericsson (Publ) Burst frame error handling
    JP2016046719A (en) * 2014-08-25 2016-04-04 株式会社東芝 Data generation device, communication device, mobile body, data generation method, and program
    FR3056043B1 (en) * 2016-09-15 2019-02-01 Continental Automotive France DEVICE FOR PROCESSING AN AUDIO SIGNAL FROM A RADIO FREQUENCY SIGNAL

    Family Cites Families (9)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    JPS5938912A (en) * 1982-08-27 1984-03-03 Nec Corp Pcm audio error compensating circuit
    CA2137459A1 (en) * 1993-05-04 1994-11-10 Stephen V. Cahill Apparatus and method for substantially eliminating noise in an audible output signal
    FI98164C (en) * 1994-01-24 1997-04-25 Nokia Mobile Phones Ltd Processing of speech coder parameters in a telecommunication system receiver
    DE4427351C1 (en) * 1994-08-02 1996-03-28 Siemens Ag Signal processing method and arrangement for block coded speech signals of a message system
    JP3264822B2 (en) * 1995-04-05 2002-03-11 三菱電機株式会社 Mobile communication equipment
    FI963870A (en) * 1996-09-27 1998-03-28 Nokia Oy Ab Masking errors in a digital audio receiver
    US6032048A (en) * 1997-03-17 2000-02-29 Ericsson Inc. Method and apparatus for compensating for click noise in an FM receiver
    JP3649854B2 (en) * 1997-05-09 2005-05-18 松下電器産業株式会社 Speech encoding device
    US6915263B1 (en) * 1999-10-20 2005-07-05 Sony Corporation Digital audio decoder having error concealment using a dynamic recovery delay and frame repeating and also having fast audio muting capabilities

    Also Published As

    Publication number Publication date
    ES2233828T3 (en) 2005-06-16
    WO2003001509A1 (en) 2003-01-03
    US20040221209A1 (en) 2004-11-04
    JP2004533021A (en) 2004-10-28
    JP4221288B2 (en) 2009-02-12
    EP1405302A1 (en) 2004-04-07
    DE50201804D1 (en) 2005-01-20
    DE10130233A1 (en) 2003-01-02

    Similar Documents

    Publication Publication Date Title
    DE19921122C1 (en) Method and device for concealing an error in a coded audio signal and method and device for decoding a coded audio signal
    DE60103424T2 (en) IMPROVING THE PERFORMANCE OF CODING SYSTEMS USING HIGH FREQUENCY RECONSTRUCTION PROCESSES
    US5682461A (en) Method of transmitting or storing digitalized, multi-channel audio signals
    DE3639753A1 (en) METHOD FOR TRANSMITTING DIGITALIZED SOUND SIGNALS
    DE4118424A1 (en) METHOD FOR PROCESSING AND PLAYING BACK RECEIVED DIGITALLY CODED AUDIO DATA AND BROADCASTING RECEIVER FOR RECEIVING DIGITALLY CODED SOUND BROADCASTING DATA (DAR)
    EP0978172A1 (en) Method for masking defects in a stream of audio data
    EP1405302B1 (en) Method for masking interference during the transfer of digital audio signals
    EP0775360B1 (en) Signal-processing method and device for substituting non-correctable blocks in a receiver for block-coded audio signals
    EP1245024B1 (en) Method for the error concealment of digital audio data by means of spectral equalisation
    DE4343366C2 (en) Method and circuit arrangement for increasing the bandwidth of narrowband speech signals
    WO1989011759A1 (en) Process for transmitting an audio signal
    EP1303856B1 (en) Method for concealing transmission errors in digital audio data
    DE2338482B2 (en) Circuit arrangement for noise reduction of a stereo broadcast broadcast according to the FCC system on the receiver side, combined with a mono-stereo display
    EP1238481B1 (en) Method for decoding digital audio data
    DE102016107799B3 (en) Method for processing an FM stereo signal
    EP1342316B1 (en) Playback device for audio signals that are transmitted over potentially disturbed channels
    DE112009002283B4 (en) Radio receiver
    DE19638546A1 (en) Method and circuit arrangement for encoding or decoding audio signals
    EP1274175B1 (en) Method of checking the reception of alternative reception frequencies in a car radio and car radio
    DE4409960A1 (en) Method for reducing the subjective perception of interference in the case of interference-free reception when using digitally transmitted audio signals
    DE102008002689A1 (en) Apparatus and method for adjusting the reproduction spectrum of two audio sources
    DE19515805C2 (en) Method for data reduction of a digitized audio signal
    DE102005051699A1 (en) Sound level variation correcting method for use in vehicle, involves detecting characteristics` changes of frequency section according to given criteria, so as to determine control variable for variation of signal amplification
    DE102005035094A1 (en) Audio signal reproducing device
    EP1672823A1 (en) Receiving apparatus for digital radio broadcasting systems

    Legal Events

    Date Code Title Description
    PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

    Free format text: ORIGINAL CODE: 0009012

    17P Request for examination filed

    Effective date: 20040122

    AK Designated contracting states

    Kind code of ref document: A1

    Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

    GRAP Despatch of communication of intention to grant a patent

    Free format text: ORIGINAL CODE: EPIDOSNIGR1

    GRAS Grant fee paid

    Free format text: ORIGINAL CODE: EPIDOSNIGR3

    GRAA (expected) grant

    Free format text: ORIGINAL CODE: 0009210

    AK Designated contracting states

    Kind code of ref document: B1

    Designated state(s): DE ES FR GB IT

    REG Reference to a national code

    Ref country code: GB

    Ref legal event code: FG4D

    Free format text: NOT ENGLISH

    REG Reference to a national code

    Ref country code: IE

    Ref legal event code: FG4D

    Free format text: GERMAN

    REF Corresponds to:

    Ref document number: 50201804

    Country of ref document: DE

    Date of ref document: 20050120

    Kind code of ref document: P

    GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)

    Effective date: 20050406

    REG Reference to a national code

    Ref country code: ES

    Ref legal event code: FG2A

    Ref document number: 2233828

    Country of ref document: ES

    Kind code of ref document: T3

    PLBE No opposition filed within time limit

    Free format text: ORIGINAL CODE: 0009261

    STAA Information on the status of an ep patent application or granted ep patent

    Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

    26N No opposition filed

    Effective date: 20050916

    ET Fr: translation filed
    PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

    Ref country code: ES

    Payment date: 20120423

    Year of fee payment: 11

    PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

    Ref country code: GB

    Payment date: 20130422

    Year of fee payment: 12

    PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

    Ref country code: IT

    Payment date: 20130424

    Year of fee payment: 12

    GBPC Gb: european patent ceased through non-payment of renewal fee

    Effective date: 20140412

    PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

    Ref country code: GB

    Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

    Effective date: 20140412

    PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

    Ref country code: IT

    Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

    Effective date: 20140412

    REG Reference to a national code

    Ref country code: ES

    Ref legal event code: FD2A

    Effective date: 20150527

    PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

    Ref country code: ES

    Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

    Effective date: 20140413

    REG Reference to a national code

    Ref country code: FR

    Ref legal event code: PLFP

    Year of fee payment: 15

    REG Reference to a national code

    Ref country code: DE

    Ref legal event code: R084

    Ref document number: 50201804

    Country of ref document: DE

    REG Reference to a national code

    Ref country code: FR

    Ref legal event code: PLFP

    Year of fee payment: 16

    PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

    Ref country code: FR

    Payment date: 20170424

    Year of fee payment: 16

    PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

    Ref country code: FR

    Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

    Effective date: 20180430

    PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

    Ref country code: DE

    Payment date: 20190627

    Year of fee payment: 18

    REG Reference to a national code

    Ref country code: DE

    Ref legal event code: R119

    Ref document number: 50201804

    Country of ref document: DE

    PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

    Ref country code: DE

    Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

    Effective date: 20201103