DE10202635B4 - Method and circuit for noise reduction - Google Patents
Method and circuit for noise reduction Download PDFInfo
- Publication number
- DE10202635B4 DE10202635B4 DE2002102635 DE10202635A DE10202635B4 DE 10202635 B4 DE10202635 B4 DE 10202635B4 DE 2002102635 DE2002102635 DE 2002102635 DE 10202635 A DE10202635 A DE 10202635A DE 10202635 B4 DE10202635 B4 DE 10202635B4
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- digital
- signal
- analog
- digital signal
- input
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain
- H04B1/0028—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at baseband stage
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain
- H04B1/0028—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at baseband stage
- H04B1/0032—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at baseband stage with analogue quadrature frequency conversion to and from the baseband
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
- H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
- H04B1/14—Automatic detuning arrangements
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/1646—Circuits adapted for the reception of stereophonic signals
- H04B1/1661—Reduction of noise by manipulation of the baseband composite stereophonic signal or the decoded left and right channels
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Analogue/Digital Conversion (AREA)
Abstract
Verfahren
zur Rauschunterdrückung für einen
Analog-Digital-Wandler
(AD) zur Wandlung eines analogen Signals in ein digitales Signal,
das in einen digitalen Signalpfad eingespeist wird, dadurch gekennzeichnet,
daß das digitale
Signal einen Signalpegel aufweist, der im digitalen Signalpfad gemessen
wird, und
daß ein
dem Signalpegel des digitalen Signals entsprechendes Steuersignal
zur Steuerung einer Tiefpassfilterung im digitalen Signalpfad vorgesehen
ist.Method for noise suppression for an analog-to-digital converter (AD) for converting an analog signal into a digital signal which is fed into a digital signal path, characterized
that the digital signal has a signal level measured in the digital signal path, and
in that a control signal corresponding to the signal level of the digital signal is provided for controlling a low-pass filtering in the digital signal path.
Description
Die Erfindung betrifft ein Verfahren und eine Schaltungsanordnung zur Rauschunterdrückung für einen Analog-Digital-Wandler zur Wandlung eines analogen Signals in ein digitales Signal, das in einen digitalen Signalpfad eingespeist wird.The The invention relates to a method and a circuit arrangement for noise reduction for one Analog to digital converter for converting an analog signal into a digital signal, the is fed into a digital signal path.
Digitale Signale, wie z. B. digitale Audiosignale, die auf einem Signalpfad übertragen werden, sind mit Rauschen behaftet, was die Klangwiedergabe hörbar beeinträchtigt. Insbesondere bei kleinen Signalpegeln, die in der Nähe des Rauschpegels liegen, nimmt die Qualität der Klangwiedergabe deutlich ab. Insbesondere Analog-Digital-Wandler zeigen ein ausgeprägtes Rauschverhalten, wie beispielsweise aus U. Tietze, Ch. Schenk: „Halbleiterschaltungstechnik", 9. Auflage, Springer Verlag, 1991, S. 770–772 bekannt ist.digital Signals, such. B. digital audio signals transmitted on a signal path are noisy, which audibly affects the sound reproduction. Especially at low signal levels, which are close to the noise level lie, the quality decreases the sound reproduction clearly. In particular analog-to-digital converter show a pronounced Noise behavior, such as, for example, U. Tietze, Ch. Schenk: "Halbleiterschaltungstechnik", 9th edition, Springer Verlag, 1991, p. 770-772 is known.
Es sind daher Maßnahmen zur Rauschunterdrückung erforderlich, die jedoch möglichst preisgünstig sein sollten.It are therefore measures for noise reduction necessary, but possible inexpensive should be.
Es ist daher Aufgabe der Erfindung, ein Verfahren und eine Schaltungsanordnung zur Rauschunterdrückung so zu gestalten, daß mit nur geringem Aufwand eine erhebliche Reduktion des Rauschens erzielt wird.It is therefore an object of the invention, a method and a circuit arrangement for noise reduction so that with achieved only a small effort a significant reduction in noise becomes.
Verfahrensmäßig wird diese Aufgabe mit den im Anspruch 1 angegebenen Merkmalen dadurch gelöst, daß das digitale Signal einen Signalpegel aufweist, der im digitalen Signalpfad gemessen wird, und daß ein dem Signalpegel des digitalen Signals entsprechendes Steuersignal zur Steuerung einer Tiefpassfilterung im digitalen Signalpfad vorgesehen ist.Procedurally this object with the features specified in claim 1 thereby solved, that this digital signal has a signal level in the digital signal path is measured, and that one the control signal corresponding to the signal level of the digital signal is provided for controlling a low-pass filtering in the digital signal path.
Vorrichtungsmäßig wird diese Aufgabe mit den im Anspruch 7 angegebenen Merkmalen dadurch gelöst, daß ein digitaler Signalpfad mit dem Eingang eines adaptiven Tiefpasses und eines Pegelmessers verbunden ist, daß der Ausgang des Pegelmessers mit dem Eingang einer Auswerteeinheit verbunden ist, die das Steuersignal für den adaptiven Tiefpaß erzeugt und daß der Ausgang der Auswerteeinheit mit dem Steuereingang des adaptiven Tiefpasses verbunden ist.Device wise this task with the features specified in claim 7 thereby solved, the existence digital signal path with the input of an adaptive low-pass filter and a level meter connected to the output of the level meter is connected to the input of an evaluation unit, which is the control signal for the generates adaptive lowpass and that the Output of the evaluation unit with the control input of the adaptive Low pass is connected.
Die Erfindung sieht einen adaptiven Tiefpaß im Signalweg vor, dessen Parameter in Abhängigkeit vom Pegel des auf dem digita len Signalpfad übertragenen digitalen Signals eingestellt werden. Der adaptive Tiefpaß bewirkt eine Bandbegrenzung des digitalen Signals und des Rauschens, so daß die Rauschleistung vermindert wird.The The invention provides an adaptive low-pass filter in the signal path, whose Parameters depending on Level of the digital signal transmitted on the digital signal path be set. The adaptive low pass causes a band limitation of the digital signal and noise, so that the noise performance is reduced becomes.
Beispielsweise sind im Signalpfad ein digitaler Signalprozessor und der adaptive Tiefpaß in Reihe geschaltet. Mittels eines Pegelmessers wird der Pegel des digitalen Signals am Ausgang des digitalen Signalprozessors gemessen und in einer Auswerteeinheit ausgewertet, welche das Steuersignal für den adaptiven Tiefpaß erzeugt.For example are in the signal path a digital signal processor and the adaptive Lowpass in Series switched. By means of a level meter, the level of the digital signal measured at the output of the digital signal processor and evaluated in an evaluation unit, which the control signal for the generates adaptive lowpass.
Die Erfindung wird anhand der Figur näher beschrieben und erläutert.The Invention will be described and explained with reference to the figure.
In der Figur ist ein Ausführungsbeispiel einer erfindungsgemäßen Schaltungsanordnung zur Unterdrückung des Rauschens in einem Signalpfad gezeigt.In The figure is an embodiment a circuit arrangement according to the invention for suppression of noise in a signal path.
Der Ausgang eines Analog-Digitel-Wandlers AD, an dessen Eingang z. B. ein analoges Audiosignal A liegt, ist mit dem Eingang eines digitalen Signalprozessors verbunden, dessen Ausgang mit dem Eingang eines Pegelmessers P und mit dem Eingang eines adaptiven Tiefpasses TP verbunden ist. Der Ausgang des Pegelmessers P ist mit dem Eingang einer Auswerteeinheit B verbunden, deren Ausgang mit dem Steuereingang des adaptiven Tiefpasses TP verbunden ist. Der Ausgang des adaptiven Tiefpasses TP ist mit dem Eingang eines Digital-Analog-Wandlers DA verbunden, an dessen Ausgang ein weitgehend rauschfreies analoges Audiosignal C abnehmbar ist.Of the Output of an analog-to-Digitel converter AD, at the input z. B. an analog audio signal A is connected to the input of a digital Signal processor connected, whose output to the input of a Level meter P and with the input of an adaptive low-pass filter TP connected is. The output of the level meter P is connected to the input of a Evaluation unit B connected, whose output to the control input the adaptive low-pass filter TP is connected. The output of the adaptive Low-pass TP is connected to the input of a digital-to-analog converter DA connected, at the output of a largely noise-free analog Audio signal C is removable.
Der Pegelmesser P ermittelt den Pegel des digitalen Audiosignals am Ausgang des digitalen Signalprozessors DP. Aus diesem Pegel leitet die Auswerteeinheit B ein Steuersignal zur Steuerung des adaptiven Tiefpasses TP ab, der das digitale Audiosignal und auch das Rauschen bandbegrenzt. Die Bandbegrenzung steigt mit abnehmendem Signalpegel.Of the Level meter P determines the level of the digital audio signal on Output of the digital signal processor DP. Derives from this level the evaluation unit B a control signal for controlling the adaptive Low-pass TP, which is the digital audio signal and also the noise band-limited. The band limitation increases with decreasing signal level.
Die Erfindung geht dabei von der ersten Erkenntnis aus, daß das Rauschen im Wesentlichen durch den Analog-Digital-Wandler bestimmt wird. Weil das Rauschen eines Analog-Digital-Wandlers verhältnismäßig breitbandig ist, kann es in erster Näherung als weißes Rauschen betrachtet werden. Die Spektralanteile eines Audiosignals, wie z. B. Musik oder Sprache, nehmen dagegen mit wachsender Frequenz ab. Deshalb tritt insbesondere bei kleinen Signalpegeln eine zunehmende Verdeckung der höherfrequenten Nutzsignalanteile durch das Rauschen ein. Der Rauscheindruck nimmt somit beim Hörer entsprechend zu. Durch die erfindungsgemäße Bandbegrenzung im Signalpfad wird nicht nur das Signal, sondern auch das Rauschen bandbegrenzt. Durch die Bandbegrenzung des Rauschens wird die Rauschleistung erheblich reduziert. Weil das menschliche Ohr für niederfrequente Signalanteile empfindlicher ist, wirkt sich eine allmählich einsetzende Bandbegrenzung nicht störend auf den Klangeindruck aus. Die erfindungsgemäße Rauschunterdrückung wirkt umso besser, je größer das Rauschen der Signalquelle, z. B. eines Analog-Digital-Wandlers, gegenüber dem Rauschen der Signalsenke, z. B. eines Digital-Analog-Wandlers, ist. Besonders vorteilhaft läßt sich die Erfindung einsetzen, wenn die Wortlänge der digitalen Signale mindestens zehn Bit beträgt.The invention is based on the first finding that the noise is essentially determined by the analog-to-digital converter. Because the noise of an analog-to-digital converter is relatively broadband, it can be considered, to a first approximation, as white noise. The spectral components of an audio signal, such. Music or speech, on the other hand, decrease with increasing frequency. Therefore, especially at low signal levels, an increasing concealment of the higher-frequency useful signal components by the noise occurs. The noise impression thus increases accordingly for the listener. Due to the band limitation according to the invention in the signal path, not only the signal but also the noise is band-limited. The band limitation of the noise is the Noise power significantly reduced. Because the human ear is more sensitive to low-frequency signal components, a gradual band limitation does not interfere with the sound impression. The noise reduction according to the invention is the better, the greater the noise of the signal source, z. As an analog-to-digital converter, compared to the noise of the signal sink, z. B. a digital-to-analog converter is. The invention can be used particularly advantageously if the word length of the digital signals is at least ten bits.
Die Erfindung ist allgemein zur Rauschunterdrückung in einem Signalpfad geeignet. Hierzu ist nur ein sehr geringer Aufwand erforderlich, der sich auf den Einsatz eines Pegelmessers, einer Auswerteeinheit und eines adaptiven Tiefpasses beschränkt.The The invention is generally suitable for noise suppression in a signal path. For this only a very small effort is required on the use of a level meter, an evaluation unit and a limited adaptive low pass.
Die Erfindung ist insbesondere für einen in einem Fahrzeug eingebauten Stereorundfunkempfänger geeignet, weil beim mobilen Empfang infolge der Topographie des gerade befahrenen Geländes häufig nur sehr schwache Empfangsfeldstärken zur Verfügung stehen. Die Erfindung ist aber auch für einen stationären Stereorundfunkempfänger geeignet, insbesondere beim Empfang von mit nur schwacher Feldstärke empfangbaren Sendern.The Invention is particularly for a stereo radio receiver installed in a vehicle, because at mobile reception as a result of the topography of the just-traveled Terrain often only very weak reception field strengths to disposal stand. However, the invention is also suitable for a stationary stereo radio receiver, in particular when receiving only weak field strength receivable stations.
- AA
- analoges Audiosignalanalog audio signal
- ADAD
- Analog-Digital-WandlerAnalog to digital converter
- BB
- Auswerteeinheitevaluation
- CC
- rauschfreies analoges Audiosignalnoise-free analog audio signal
- DATHERE
- Digital-Analog-WandlerDigital to analog converter
- DPDP
- digitaler Signalprozessordigital signal processor
- PP
- PegelmesserPower meter
- TPTP
- adaptiver Tiefpaßadaptive lowpass
Claims (13)
Priority Applications (1)
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DE2002102635 DE10202635B4 (en) | 2002-01-24 | 2002-01-24 | Method and circuit for noise reduction |
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DE2002102635 DE10202635B4 (en) | 2002-01-24 | 2002-01-24 | Method and circuit for noise reduction |
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DE10202635A1 DE10202635A1 (en) | 2003-08-07 |
DE10202635B4 true DE10202635B4 (en) | 2006-05-24 |
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DE2002102635 Expired - Fee Related DE10202635B4 (en) | 2002-01-24 | 2002-01-24 | Method and circuit for noise reduction |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8803594B2 (en) | 2009-11-30 | 2014-08-12 | Aisin Seiki Kabushiki Kaisha | Device for electromagnetic noise reduction in a hybrid automotive vehicle, assembly and electromagnetic noise reduction process in a hybrid automotive vehicle |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0423708D0 (en) | 2004-10-26 | 2004-11-24 | Koninkl Philips Electronics Nv | Adapting filter to detected interference level |
TWI433137B (en) | 2009-09-10 | 2014-04-01 | Dolby Int Ab | Improvement of an audio signal of an fm stereo radio receiver by using parametric stereo |
JP6015279B2 (en) | 2012-09-20 | 2016-10-26 | アイシン精機株式会社 | Noise removal device |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4322641A (en) * | 1979-12-11 | 1982-03-30 | Packburn Electronics | Noise reduction system |
-
2002
- 2002-01-24 DE DE2002102635 patent/DE10202635B4/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4322641A (en) * | 1979-12-11 | 1982-03-30 | Packburn Electronics | Noise reduction system |
Non-Patent Citations (1)
Title |
---|
TIETZE, U., SCHENK, Ch.: Halbleiterschaltungs- technik, 9. Aufl., Springer-Verlag, Berlin, ISBN 3-540-19475-4, 1991, S. 770-772 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8803594B2 (en) | 2009-11-30 | 2014-08-12 | Aisin Seiki Kabushiki Kaisha | Device for electromagnetic noise reduction in a hybrid automotive vehicle, assembly and electromagnetic noise reduction process in a hybrid automotive vehicle |
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DE10202635A1 (en) | 2003-08-07 |
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8327 | Change in the person/name/address of the patent owner |
Owner name: HARMAN BECKER AUTOMOTIVE SYSTEMS GMBH, 76307 KARLS |
|
8364 | No opposition during term of opposition | ||
R119 | Application deemed withdrawn, or ip right lapsed, due to non-payment of renewal fee |