EP1091534A1 - High efficiency transmission channel - Google Patents

High efficiency transmission channel Download PDF

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Publication number
EP1091534A1
EP1091534A1 EP00402725A EP00402725A EP1091534A1 EP 1091534 A1 EP1091534 A1 EP 1091534A1 EP 00402725 A EP00402725 A EP 00402725A EP 00402725 A EP00402725 A EP 00402725A EP 1091534 A1 EP1091534 A1 EP 1091534A1
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EP
European Patent Office
Prior art keywords
signal
length
volume
loudspeaker
modulator
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EP00402725A
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German (de)
French (fr)
Inventor
Nicolas Moeneclaey
Pierre Genest
Frank Op't Eynde
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Alcatel Lucent SAS
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Alcatel CIT SA
Alcatel SA
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Publication of EP1091534A1 publication Critical patent/EP1091534A1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones

Definitions

  • the present invention relates to the field of reception chains audio especially in portable low power systems.
  • Patent application FR-A-2765419 describes a device for generation of analog signals from analog to digital converters. he describes the use of a Sigma-Delta modulator in signal transmission digital, as well as the generation of analog signals, without however allowing control the output volume in a simple way.
  • the digital signal to analog signal converter includes usually a volume control. We then have a low-pass filter allowing eliminate the sampling components, as well as a power.
  • the power amplifier consumes a lot of power and lowers the efficiency of the general circuit. This system is not satisfactory because, even if they allow a volume adjustment, it requires a large number of analog components such as a 1 bit digital to analog converter, active filters, amplifier power. These components are integrated on a dedicated chip.
  • This second solution although essentially digital, does not allow not control the output volume without lowering the signal to noise ratio due to adding additional components. It has the advantage of requiring only one discrete passive filter (based on RLC components) in addition to the digital part but does not does not allow volume adjustment.
  • the Sigma-Delta modulator is used to pass from a word of N bits to a word of M bits, M being less than N, by eliminating the truncation error in the useful signal band, which is the band in which the sinusoid or other signal is synthesized. The spectral components linked to this truncation are then rejected out of this band.
  • the length of the output words is 1 bit.
  • the output flow is faster than the input one and can be adjusted to obtain an integer multiplication factor.
  • the invention seeks to improve the efficiency of the audio reception channel of the second solution while using a minimum of linear components, power dissipators.
  • This channel should convert the digital input data to a analog signal to allow volume control by the user, without loss in the signal-to-noise ratio, and drive a low impedance speaker.
  • the invention relates to an audio reception system comprising a modulator for modulating a first digital audio signal with a first rate in a second digital audio signal with a second rate higher than the first, said second signal comprising a plurality of words of 1 bit length over a period predetermined; as well as an output device comprising a loudspeaker and means for transmitting the second signal, in analog form, to the loudspeaker.
  • these means are transistors of switching of a class D output.
  • the system further includes a control device, connected to a part to the modulator by receiving the second signal, and secondly to the output device.
  • the control device is able to control the output device from a part of said predetermined period, the length of said part being determined as a function desired volume.
  • the invention also relates to an audio reception method comprising a step of modulating a first digital audio signal with a first rate in a second digital audio signal with a second rate greater than first, said signal comprising a plurality of words of length of 1 bit on a predetermined period and a step of receiving said second signal in a loudspeaker.
  • the first digital audio signal is advantageously modulated in a first modulator of the Sigma-Delta type and comprises a plurality of words length of 1 bit.
  • the loudspeaker Prior to the reception step, the loudspeaker is controlled depending on part of said predetermined period, the length of said part being determined according to the desired volume. Alternatively, the length of said part controls a short circuit of the power supply.
  • the Sigma-Delta modulator output signal is a 1-bit stream, with a frequency higher than the Nyquist frequency.
  • the quantization noise at this output is mainly located in the high frequencies.
  • the filter low pass in class D output is constituted by a second order RLC filter in which resistance forms the speaker.
  • the digital information transmitted in the signal makes it possible to control the volume by modifying the length of each output data ("0" or "1") of the stream given by the Sigma-Delta modulator.
  • the Sigma-Delta modulator output signal is at frequency Fe.
  • Te two subdivisions are used. The first subdivision corresponds to time during which the load is connected to supply S or -S, depending on the signal value of the Sigma-Delta modulator (Sdout). The second corresponds to the time during which the load is shorted to ground.
  • the value of the duration ratio of two subdivisions is used to adjust the volume.
  • a non-overlapping period ensures that the NMOS and PMOS on the same side are not conductive at the same time.
  • Each period of the Sigma-Delta modulator output signal is divided into two subdivisions: the first corresponds to the time during which the loudspeaker is powered, and the second corresponds to the time during which it is passive. The value of the ratio between these two subdivisions is used to adjust the volume.
  • All mobile terminals with reception means digital audio can use the system according to the invention.
  • the invention avoids the addition of a linear device such as a operational amplifier or grouped capacities.
  • the digital process is simplified, which reduces the cost of the function. Precision of control volume is based on the accuracy of the main clock.
  • FIG. 1 represents a general diagram of the system according to the invention.
  • Figure 2 shows an example of signal coding and signals across the various inputs.
  • the control device 2 is arranged after the Sigma-Delta 1 modulator and receives its output signal, as can be seen in the figure 1.
  • the signal is then modulated in the control device 2 at a frequency Fc multiple of that of output Fe of the modulator Sigma-Delta 1.
  • Fc 12MhZ.
  • the modulation is carried out thanks to a second clock 3.
  • This second clock can be coupled to the modulator clock Sigma-Delta 4.
  • This control device 2 thus integrates the data linked to the volume in signal subdivisions, defining the time intervals that contain the useful signal.
  • the output device 11 represents a class D output bridge.
  • different dipole terminals CMDP, CMDPZ, CMDM, CMDMZ
  • This bridge comprises, in a conventional manner, an RLC bridge 5.
  • This RLC bridge allows a filter to be produced low pass improving the quality of the sound signal emitted by the resistor 10 which plays the speaker role.
  • the low-pass filter can be made from another way.
  • the output device 11 is on the one hand supplied by a fixed voltage V and on the other hand grounded.
  • the system according to the invention is intended for static adjustment of the volume: it is well known that a user adjusts the volume of his device one by two times during use.
  • the invention also makes use of the fact that at high frequency, the user does not hear the temporary interruptions of sound emission.
  • FIG. 2 shows how the volume is modulated in the transmitted signal.
  • the useful signal is transmitted in the first three periods Tc (corresponding to the output frequency Fc) of the wave train.
  • Tc corresponding to the output frequency Fc
  • the numerical values chosen in this example allow to have six periods Tc in a period Te.
  • the loudspeaker instead of being used once in time Te, is requested Tt / Tc times in time Tt.
  • the volume adjustment consists to define this number Tt / Tc.
  • the human ear does not notice the change in speaker frequency.
  • the 1-bit words at the frequency Fe are represented in the line 6.
  • Lines 7 and 8 respectively represent the periods Tc and Te.
  • All lines 9a, 9b, 9c, 9d respectively represent the signal at the terminals CMDP, CMDPZ, CMDM, CMDMZ of the output bridge.
  • Information regarding the volume is then the ratio Tt / Te.
  • the three periods following Tt are unused, in particular in the absence of passive filter at the terminals in a first variant. To suppress noise, a filter passive is added.
  • any element allowing to split the signal period into sub-periods can replace the clock.
  • any other cutting can be used, which will complicate the reading volume information.
  • any type of signal distribution is possible in the main period Te.
  • Tt / Tc The most important information is the overall number of sub-periods used: Tt / Tc. These periods do not have to be all consecutive.
  • the part of the predetermined period allowing adjusting the volume has non-consecutive sub-periods.
  • the total length Tt always contains the information.
  • a variant consists in modifying the distribution of the useful signals by volume function. This variant makes it possible to optimize the use of the different components.

Abstract

The invention concerns an audio receiver system comprising: a modulator (1) for modulating a first digital audio signal with a first factor and a second digital audio signal with a second factor greater than the first, said second signal comprising a plurality of words having length of 1 bit over a predetermined time interval; an output device (11) comprising a loudspeaker (10) and means for transmitting the second signal to the loudspeaker (10) in analog form. The invention is characterised in that it further comprises a control device (2) connected to the modulator (1) on receiving the second signal and to the output device (11), the control device being capable of controlling the output device as from part of said predetermined time interval, the length of said part being determined on the basis of the desired volume.

Description

La présente invention concerne le domaine des chaínes de réception audio en particulier dans les systèmes portables de faible consommation.The present invention relates to the field of reception chains audio especially in portable low power systems.

Différents systèmes existent pour transformer un signal numérique en signal analogique de puissance qui permet d'émettre des sons par le biais d'un haut-parleur.Different systems exist to transform a digital signal into analog power signal that allows sounds to be emitted through a loudspeaker.

La demande de brevet FR-A-2765419 décrit un dispositif de génération de signaux analogiques à partir de convertisseurs analogique-numérique. Il décrit l'utilisation d'un modulateur Sigma-Delta dans la transmission du signal numérique, ainsi que la génération des signaux analogiques, sans permettre toutefois de contrôler le volume de sortie de manière simple.Patent application FR-A-2765419 describes a device for generation of analog signals from analog to digital converters. he describes the use of a Sigma-Delta modulator in signal transmission digital, as well as the generation of analog signals, without however allowing control the output volume in a simple way.

Le convertisseur de signal numérique en signal analogique comporte en général un contrôle du volume. On dispose ensuite un filtre passe-bas permettant d'éliminer les composantes liées à l'échantillonnage, ainsi qu'un amplificateur de puissance. L'amplificateur de puissance consomme beaucoup de puissance et abaisse l'efficacité du circuit général. Ce système n'est pas satisfaisant car, même s'ils permet un réglage du volume, il nécessite un grand nombre de composants analogiques tel qu'un convertisseur digital vers analogique 1 bit, des filtres actifs, un amplificateur de puissance. Ces composants sont intégrés sur une puce dédiée.The digital signal to analog signal converter includes usually a volume control. We then have a low-pass filter allowing eliminate the sampling components, as well as a power. The power amplifier consumes a lot of power and lowers the efficiency of the general circuit. This system is not satisfactory because, even if they allow a volume adjustment, it requires a large number of analog components such as a 1 bit digital to analog converter, active filters, amplifier power. These components are integrated on a dedicated chip.

Afin de générer le son transmis par le canal audionumérique, il est connu d'utiliser un modulateur Sigma-Delta suivi d'un dispositif permettant de convertir le signal numérique en signal analogique et des dispositifs permettant de filtrer le bruit créé lors de la transmission, ainsi qu'un dispositif de génération du son. Le modulateur Sigma-Delta est généralement suivi d'une sortie de classe D.In order to generate the sound transmitted by the digital audio channel, it is known to use a Sigma-Delta modulator followed by a device to convert the digital signal to analog signal and devices to filter the noise created during transmission, as well as a sound generation device. The modulator Sigma-Delta is generally followed by a class D outing.

Cette deuxième solution, bien qu'essentiellement numérique ne permet pas de contrôler le volume de sortie sans abaisser le rapport signal sur bruit du fait de l'ajout de composants supplémentaires. Elle présente l'avantage de ne nécessiter qu'un filtre passif discret (à base de composants RLC) en plus de la partie numérique mais ne permet pas le réglage du volume.This second solution, although essentially digital, does not allow not control the output volume without lowering the signal to noise ratio due to adding additional components. It has the advantage of requiring only one discrete passive filter (based on RLC components) in addition to the digital part but does not does not allow volume adjustment.

Le modulateur Sigma-Delta est utilisé pour passer d'un mot de N bits à un mot de M bits, M étant inférieur à N, en éliminant l'erreur de troncature dans la bande de signaux utiles, qui est la bande dans laquelle la sinusoïde ou un autre signal est synthétisé. Les composantes spectrales liées à cette troncature sont ensuite rejetées hors de cette bande. Dans l'application selon l'invention, la longueur des mots de sortie est de 1 bit. De plus, à la sortie du modulateur, le débit de sortie est plus rapide que celui d'entrée et peut être réglé pour obtenir un facteur entier de multiplication.The Sigma-Delta modulator is used to pass from a word of N bits to a word of M bits, M being less than N, by eliminating the truncation error in the useful signal band, which is the band in which the sinusoid or other signal is synthesized. The spectral components linked to this truncation are then rejected out of this band. In the application according to the invention, the length of the output words is 1 bit. In addition, at the output of the modulator, the output flow is faster than the input one and can be adjusted to obtain an integer multiplication factor.

L'invention cherche à améliorer l'efficacité du canal de réception audio de la seconde solution tout en utilisant un minimum de composants linéaires, dissipateurs de puissance. Ce canal doit convertir les données d'entrée numériques en un signal analogique pour permettre un contrôle du volume par l'utilisateur, sans perte dans le rapport signal-bruit, et piloter un haut-parleur à faible impédance.The invention seeks to improve the efficiency of the audio reception channel of the second solution while using a minimum of linear components, power dissipators. This channel should convert the digital input data to a analog signal to allow volume control by the user, without loss in the signal-to-noise ratio, and drive a low impedance speaker.

L'invention concerne un système de réception audio comprenant un modulateur pour moduler un premier signal audionumérique avec un premier taux en un second signal audionumérique avec un second taux supérieur au premier, ledit second signal comprenant une pluralité de mots de longueur de 1 bit sur une période prédéterminée ; ainsi qu'un dispositif de sortie comportant un haut-parleur et des moyens pour transmettre le second signal, sous forme analogique, au haut-parleur.The invention relates to an audio reception system comprising a modulator for modulating a first digital audio signal with a first rate in a second digital audio signal with a second rate higher than the first, said second signal comprising a plurality of words of 1 bit length over a period predetermined; as well as an output device comprising a loudspeaker and means for transmitting the second signal, in analog form, to the loudspeaker.

Suivant une réalisation particulière, ces moyens sont des transistors de commutation d'une sortie de classe D.According to a particular embodiment, these means are transistors of switching of a class D output.

Le système comporte en outre un dispositif de contrôle, connecté d'une part au modulateur en recevant le second signal, et d'autre part au dispositif de sortie. Le dispositif de contrôle est apte à contrôler le dispositif de sortie à partir d'une partie de ladite période prédéterminée, la longueur de ladite partie étant déterminée en fonction du volume désiré.The system further includes a control device, connected to a part to the modulator by receiving the second signal, and secondly to the output device. The control device is able to control the output device from a part of said predetermined period, the length of said part being determined as a function desired volume.

L'invention concerne également un procédé de réception audio comprenant une étape de modulation d'un premier signal audionumérique avec un premier taux en un second signal audionumérique avec un second taux supérieur au premier, ledit signal comprenant une pluralité de mots de longueur de 1 bit sur une période prédéterminée et une étape de réception dudit second signal dans un haut-parleur.The invention also relates to an audio reception method comprising a step of modulating a first digital audio signal with a first rate in a second digital audio signal with a second rate greater than first, said signal comprising a plurality of words of length of 1 bit on a predetermined period and a step of receiving said second signal in a loudspeaker.

Le premier signal audionumérique est avantageusement modulé dans un premier modulateur du type Sigma-Delta et comporte une pluralité de mots de longueur de 1 bit.The first digital audio signal is advantageously modulated in a first modulator of the Sigma-Delta type and comprises a plurality of words length of 1 bit.

Préalablement à l'étape de réception, le haut-parleur est commandé en fonction d'une partie de ladite période prédéterminée, la longueur de ladite partie étant déterminée en fonction du volume désiré. Dans une variante, la longueur de ladite partie commande un court-circuit de l'alimentation.Prior to the reception step, the loudspeaker is controlled depending on part of said predetermined period, the length of said part being determined according to the desired volume. Alternatively, the length of said part controls a short circuit of the power supply.

Le signal de sortie du modulateur Sigma-Delta est un flux de 1 bit, avec une fréquence supérieure à la fréquence de Nyquist. Le bruit de quantification à cette sortie se situe principalement dans les hautes fréquences. On pilote directement les transistors de commutation de la sortie de classe D avec cet échantillonnage. Le filtre passe-bas dans la sortie de classe D est constitué par un filtre RLC du second ordre dans lequel la résistance forme le haut-parleur.The Sigma-Delta modulator output signal is a 1-bit stream, with a frequency higher than the Nyquist frequency. The quantization noise at this output is mainly located in the high frequencies. We directly pilot Class D output switching transistors with this sampling. The filter low pass in class D output is constituted by a second order RLC filter in which resistance forms the speaker.

L'information numérique transmise dans le signal permet de contrôler le volume en modifiant la longueur de chaque donnée de sortie ("0" ou "1") du flux donné par le modulateur Sigma-Delta.The digital information transmitted in the signal makes it possible to control the volume by modifying the length of each output data ("0" or "1") of the stream given by the Sigma-Delta modulator.

Le signal de sortie du modulateur Sigma-Delta est à la fréquence Fe. Le pilote de l'étape suivante a une fréquence de N*Fe, où N est un nombre entier, ce qui permet de diviser la période Te, associée à la fréquence Fe (Te=1/Fe). Pendant une période Te, on utilise deux subdivisions. La première subdivision correspond au temps pendant lequel la charge est connectée à l'alimentation S ou -S, selon la valeur du signal de sortie du modulateur Sigma-Delta (Sdout). La seconde correspond au temps pendant lequel la charge est court-circuité à la masse.The Sigma-Delta modulator output signal is at frequency Fe. The pilot of the next step has a frequency of N * Fe, where N is an integer, which divides the period Te, associated with the frequency Fe (Te = 1 / Fe). During a period Te, two subdivisions are used. The first subdivision corresponds to time during which the load is connected to supply S or -S, depending on the signal value of the Sigma-Delta modulator (Sdout). The second corresponds to the time during which the load is shorted to ground.

La valeur du rapport de la durée de deux subdivisions est utilisée pour régler le volume.The value of the duration ratio of two subdivisions is used to adjust the volume.

Pour éviter une consommation excessive de puissance, ou la destruction des transistors MOS, une période de non chevauchement (TN) garantit que le NMOS et le PMOS du même côté ne sont pas conducteur au même moment.To avoid excessive power consumption, or destruction of the MOS transistors, a non-overlapping period (TN) ensures that the NMOS and PMOS on the same side are not conductive at the same time.

Chaque période du signal de sortie du modulateur Sigma-Delta est divisée en deux subdivisions : la première correspond au temps pendant lequel le haut-parleur est alimenté, et la seconde correspond au temps pendant lequel il est passif. La valeur du rapport entre ces deux subdivisions est utilisée pour régler le volume.Each period of the Sigma-Delta modulator output signal is divided into two subdivisions: the first corresponds to the time during which the loudspeaker is powered, and the second corresponds to the time during which it is passive. The value of the ratio between these two subdivisions is used to adjust the volume.

Tous les terminaux mobiles comportant des moyens de réception audionumérique peuvent utiliser le système selon l'invention.All mobile terminals with reception means digital audio can use the system according to the invention.

L'invention permet d'éviter l'ajout d'un dispositif linéaire comme un amplificateur opérationnel ou des capacités groupées. De plus, le processus numérique est simplifié, ce qui permet de diminuer le coût de la fonction. La précision du contrôle du volume repose sur la précision de l'horloge principale.The invention avoids the addition of a linear device such as a operational amplifier or grouped capacities. In addition, the digital process is simplified, which reduces the cost of the function. Precision of control volume is based on the accuracy of the main clock.

La figure 1 représente un schéma général du système selon l'invention.FIG. 1 represents a general diagram of the system according to the invention.

La figure 2 représente un exemple de codage du signal et les signaux aux bornes des différentes entrées.Figure 2 shows an example of signal coding and signals across the various inputs.

Le dispositif de contrôle 2 selon l'invention est disposé après le modulateur Sigma-Delta 1 et reçoit son signal de sortie, comme on peut le voir dans la figure 1. Le signal est alors modulé dans le dispositif de contrôle 2 à une fréquence Fc multiple de celle de sortie Fe du modulateur Sigma-Delta 1. Dans cet exemple, m=6 et Fe=2MhZ, de telle manière que Fc=12MhZ. La modulation est effectuée grâce à une seconde horloge 3. Cette seconde horloge peut être couplée à l'horloge du modulateur Sigma-Delta 4. Ce dispositif de contrôle 2 intègre ainsi les données liées au volume dans les subdivisions du signal, en définissant les intervalles de temps qui contiennent le signal utile.The control device 2 according to the invention is arranged after the Sigma-Delta 1 modulator and receives its output signal, as can be seen in the figure 1. The signal is then modulated in the control device 2 at a frequency Fc multiple of that of output Fe of the modulator Sigma-Delta 1. In this example, m = 6 and Fe = 2MhZ, so that Fc = 12MhZ. The modulation is carried out thanks to a second clock 3. This second clock can be coupled to the modulator clock Sigma-Delta 4. This control device 2 thus integrates the data linked to the volume in signal subdivisions, defining the time intervals that contain the useful signal.

Le dispositif de sortie 11 représente un pont de sortie de classe D. Les différentes bornes du dipôle (CMDP, CMDPZ, CMDM, CMDMZ) permettent de contrôler le signal de sortie, en fonction du signal émis par le dispositif de contrôle 2. Ce pont comporte, de manière classique, un pont RLC 5. Ce pont RLC permet de réaliser un filtre passe-bas améliorant la qualité du signal sonore émis par la résistance 10 qui joue le rôle de haut-parleur. Bien entendu, le filtre passe-bas peut être réalisé d'une autre manière. Le dispositif de sortie 11 est d'une part alimenté par une tension V fixe et d'autre part mis à la masse.The output device 11 represents a class D output bridge. different dipole terminals (CMDP, CMDPZ, CMDM, CMDMZ) allow you to control the output signal, depending on the signal emitted by the control device 2. This bridge comprises, in a conventional manner, an RLC bridge 5. This RLC bridge allows a filter to be produced low pass improving the quality of the sound signal emitted by the resistor 10 which plays the speaker role. Of course, the low-pass filter can be made from another way. The output device 11 is on the one hand supplied by a fixed voltage V and on the other hand grounded.

Le système selon l'invention est destiné à un réglage statique du volume : il est bien connu qu'un utilisateur règle le volume de son appareil une à deux fois lors de l'utilisation. L'invention utilise également le fait qu'à haute fréquence, l'utilisateur n'entend pas les interruptions temporaires d'émission sonore.The system according to the invention is intended for static adjustment of the volume: it is well known that a user adjusts the volume of his device one by two times during use. The invention also makes use of the fact that at high frequency, the user does not hear the temporary interruptions of sound emission.

La figure 2 permet de comprendre comment le volume est modulé dans le signal transmis. Dans ce cas, le signal utile est transmis dans les trois premières périodes Tc (correspondant à la fréquence de sortie Fc) du train d'ondes. On note cette valeur Tt. Les valeurs numériques choisies dans cet exemple permettent de disposer de six périodes Tc dans une période Te. Le haut-parleur, au lieu d'être sollicité une fois dans le temps Te, est sollicité Tt/Tc fois dans le temps Tt. Le réglage du volume consiste à définir ce nombre Tt/Tc.Figure 2 shows how the volume is modulated in the transmitted signal. In this case, the useful signal is transmitted in the first three periods Tc (corresponding to the output frequency Fc) of the wave train. We note this Tt value. The numerical values chosen in this example allow to have six periods Tc in a period Te. The loudspeaker, instead of being used once in time Te, is requested Tt / Tc times in time Tt. The volume adjustment consists to define this number Tt / Tc.

L'oreille humaine ne permet pas de remarquer le changement de fréquence du haut-parleur. Les mots de 1 bits à la fréquence Fe sont représentés dans la ligne 6. Les lignes 7 et 8 représentent respectivement les périodes Tc et Te. L'ensemble des lignes 9a, 9b, 9c, 9d représentent respectivement le signal aux bornes CMDP, CMDPZ, CMDM, CMDMZ du pont de sortie. Dans cette exemple, le signal utile est transmis dans les trois premières périodes Tc : Tt/Tc=3. L'information concernant le volume est alors le rapport Tt/Te.The human ear does not notice the change in speaker frequency. The 1-bit words at the frequency Fe are represented in the line 6. Lines 7 and 8 respectively represent the periods Tc and Te. All lines 9a, 9b, 9c, 9d respectively represent the signal at the terminals CMDP, CMDPZ, CMDM, CMDMZ of the output bridge. In this example, the useful signal is transmitted in the first three periods Tc: Tt / Tc = 3. Information regarding the volume is then the ratio Tt / Te.

Les trois périodes suivant Tt sont inutilisées, en particulier en l'absence de filtre passif aux bornes dans une première variante. Pour supprimer le bruit, un filtre passif est ajouté. The three periods following Tt are unused, in particular in the absence of passive filter at the terminals in a first variant. To suppress noise, a filter passive is added.

Dans le cas d'une utilisation sans filtre passif, il est avantageux mais non obligatoire d'effectuer un court-circuit pendant les périodes résiduelles afin d'éliminer les charges résiduelles. Dans le cas où l'on utilise un filtre passif, un court-circuit permet d'éviter que des charges demeurent et dégradent ledit filtre. L'usage du filtre passif sans court-circuit oblige à employer des moyens supplémentaires qui nuisent à l'efficacité et à la simplicité du dispositif, afin d'éliminer les charges résiduelles.In the case of use without a passive filter, it is advantageous but not compulsory to carry out a short circuit during the residual periods in order to eliminate residual charges. If a passive filter is used, a short circuit prevents charges from remaining and degrading said filter. The use of passive filter without short circuit requires the use of additional means which are harmful the efficiency and simplicity of the device, in order to eliminate residual charges.

Tout élément permettant de découper la période du signal en sous-périodes peut remplacer l'horloge. En particulier, si un découpage en périodes régulières est plus avantageux, tout autre découpage peut être utilisé, ce qui compliquera la lecture de l'information concernant le volume. Pour un réglage de volume donné, tout type de répartition du signal est possible dans la période principale Te.Any element allowing to split the signal period into sub-periods can replace the clock. In particular, if a division into regular periods is more advantageous, any other cutting can be used, which will complicate the reading volume information. For a given volume setting, any type of signal distribution is possible in the main period Te.

L'information la plus importante consiste en le nombre global de sous-périodes utilisées : Tt/Tc. Il n'est pas obligatoire que ces périodes soient toutes consécutives.The most important information is the overall number of sub-periods used: Tt / Tc. These periods do not have to be all consecutive.

Dans ce cas, la partie de la période prédéterminée permettant de régler le volume comporte des sous-périodes non consécutives. La longueur totale Tt contient toujours l'information.In this case, the part of the predetermined period allowing adjusting the volume has non-consecutive sub-periods. The total length Tt always contains the information.

Il est nécessaire que cette répartition soit reproductible.This distribution must be reproducible.

Une variante consiste à modifier la répartition des signaux utiles en fonction du volume. Cette variante permet d'optimiser l'utilisation des différents composants.A variant consists in modifying the distribution of the useful signals by volume function. This variant makes it possible to optimize the use of the different components.

Claims (8)

Système de réception audio comprenant : Un modulateur (1 ) pour moduler un premier signal audionumérique avec un premier taux en un second signal audionumérique avec un second taux supérieur au premier, ledit second signal comprenant une pluralité de mots de longueur de 1 bit sur une période prédéterminée; Un dispositif de sortie (11) comportant un haut-parleur (10) et des moyens pour transmettre le second signal, sous forme analogique, au haut-parleur (10);    caractérisé en ce qu'il comporte en outre un dispositif de contrôle (2), connecté d'une part au modulateur (1) en recevant le second signal et d'autre part au dispositif de sortie (11), le dispositif de contrôle étant apte à contrôler le dispositif de sortie (11) à partir d'une partie de ladite période prédéterminée, la longueur de ladite partie étant déterminée en fonction du volume désiré.Audio reception system comprising: A modulator (1) for modulating a first digital audio signal with a first rate into a second digital audio signal with a second rate greater than the first, said second signal comprising a plurality of words of length of 1 bit over a predetermined period; An output device (11) comprising a loudspeaker (10) and means for transmitting the second signal, in analog form, to the loudspeaker (10); characterized in that it further comprises a control device (2), connected on the one hand to the modulator (1) by receiving the second signal and on the other hand to the output device (11), the control device being able to control the output device (11) from a part of said predetermined period, the length of said part being determined as a function of the desired volume. Système de réception audio selon la revendication 1 caractérisé en ce que le dispositif de sortie comporte un filtre passif sur le haut-parleur.Audio reception system according to claim 1 characterized in that the output device has a passive filter on the speaker. Système de réception audio selon la revendication 1 ou 2 caractérisé en ce que la partie de la période prédéterminée permettant de régler le volume comporte des sous-parties non toutes consécutives.Audio reception system according to claim 1 or 2 characterized in that the part of the predetermined period for adjusting the volume has sub-parts not all consecutive. Système de réception audio selon la revendication 3 caractérisé en ce que la répartition des sous-parties non toutes consécutives est fonction du volume désiré.Audio reception system according to claim 3 characterized in that the distribution of not all consecutive sub-parts depends on the volume longed for. Terminal caractérisé en ce qu'il comporte un système de réception audio selon l'une des revendications 1 à 4.Terminal characterized in that it includes a reception system audio according to one of claims 1 to 4. Procédé de réception audio comprenant : une étape de modulation (3) d'un premier signal audionumérique avec un premier taux en un second signal audionumérique avec un second taux supérieur au premier, ledit signal comprenant une pluralité de mots de longueur de 1 bit sur une période prédéterminée; une étape de réception dudit second signal dans un haut-parleur (10);    caractérisé en ce que préalablement à l'étape de réception, le haut-parleur est commandé en fonction d'une partie de ladite période prédéterminée, la longueur de ladite partie étant déterminée en fonction du volume désiré. Audio reception method comprising: a step of modulating (3) a first digital audio signal with a first rate into a second digital audio signal with a second rate greater than the first, said signal comprising a plurality of words of length of 1 bit over a predetermined period; a step of receiving said second signal in a loudspeaker (10); characterized in that prior to the receiving step, the loudspeaker is controlled as a function of part of said predetermined period, the length of said part being determined as a function of the desired volume. Procédé de réception audio selon la revendication 6 caractérisé en ce que la longueur de ladite partie commande un court-circuit de l'alimentation.Audio reception method according to claim 6 characterized in that the length of said part controls a short circuit of the power supply. Procédé de réception audio selon la revendication 6 ou 7 caractérisé en ce que le premier signal audionumérique est modulé dans un modulateur (1) et comporte une pluralité de mots de longueur de 1 bit.Audio reception method according to claim 6 or 7 characterized in that the first digital audio signal is modulated in a modulator (1) and includes a plurality of words of 1 bit length.
EP00402725A 1999-10-04 2000-10-04 High efficiency transmission channel Withdrawn EP1091534A1 (en)

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FR9912350 1999-10-04
FR9912350A FR2799325B1 (en) 1999-10-04 1999-10-04 HIGH EFFICIENCY AUDIO TRANSMISSION CHANNEL

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JP (1) JP4152105B2 (en)
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US6727752B2 (en) * 2002-05-29 2004-04-27 Texas Instruments Incorporated Modulation scheme for switching amplifiers to reduce filtering requirements and crossover distortion

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US5398003A (en) * 1994-03-30 1995-03-14 Apple Computer, Inc. Pulse width modulation speaker amplifier
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FR2765419A1 (en) * 1997-06-27 1998-12-31 Thomson Csf DEVICE FOR GENERATING ANALOG SIGNALS FROM ANALOG-TO-DIGITAL CONVERTERS, PARTICULARLY FOR DIRECT DIGITAL SYNTHESIS

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FR2799325B1 (en) 2002-05-31
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CN1212045C (en) 2005-07-20
WO2001026416A3 (en) 2001-08-30
US6597241B1 (en) 2003-07-22
FR2799325A1 (en) 2001-04-06
JP4152105B2 (en) 2008-09-17
AU7793700A (en) 2001-05-10

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