WO2005055477A1 - Method of masking an unwanted electromagnetic noise generated by a motor vehicle computer and corresponding device - Google Patents
Method of masking an unwanted electromagnetic noise generated by a motor vehicle computer and corresponding device Download PDFInfo
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- WO2005055477A1 WO2005055477A1 PCT/EP2004/013835 EP2004013835W WO2005055477A1 WO 2005055477 A1 WO2005055477 A1 WO 2005055477A1 EP 2004013835 W EP2004013835 W EP 2004013835W WO 2005055477 A1 WO2005055477 A1 WO 2005055477A1
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- noise
- vehicle
- parasitic
- masking
- magnetic field
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R25/00—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles
- B60R25/20—Means to switch the anti-theft system on or off
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R25/00—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles
- B60R25/01—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles operating on vehicle systems or fittings, e.g. on doors, seats or windscreens
- B60R25/04—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles operating on vehicle systems or fittings, e.g. on doors, seats or windscreens operating on the propulsion system, e.g. engine or drive motor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R25/00—Fittings or systems for preventing or indicating unauthorised use or theft of vehicles
- B60R25/20—Means to switch the anti-theft system on or off
- B60R25/2072—Means to switch the anti-theft system on or off with means for preventing jamming or interference of a remote switch control signal
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B15/00—Suppression or limitation of noise or interference
- H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
- G07C9/00—Individual registration on entry or exit
- G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
- G07C2009/00753—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys
- G07C2009/00769—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means
- G07C2009/00793—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means by Hertzian waves
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
- G07C9/00—Individual registration on entry or exit
- G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
- G07C9/00309—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks
Definitions
- the present invention relates to a method for masking parasitic electromagnetic noise generated by a motor vehicle control unit and a corresponding device. More particularly, it is a computer placed in the passenger compartment of the vehicle and suitable for controlling access and "hands-free" starting of the vehicle. Interference noise is generated when the vehicle's internal antennas are activated. It is already known to provide a motor vehicle with a so-called "hands-free" system. Such a system allows the holder of a badge to lock or unlock access to his vehicle without having to actuate remote control buttons.
- a radio frequency (eg 433 MHz) and / or low frequency (eg 125 kHz) dialogue is established between a badge and the vehicle so that when the badge is approached, the vehicle detects the presence of the latter and unlocks the vehicle. Likewise when the badge is removed, the vehicle is locked.
- This hands-free system can be extended to the vehicle starting function. In this case when the badge is detected inside the vehicle, pressing a start button causes the engine to start.
- Such a "hands-free" access and starting system therefore requires being able to very precisely locate the badge (s) relative to the vehicle.
- the vehicle is provided with antennas (transmitter / receiver) both outside and inside the vehicle.
- the vehicle must in particular be able to detect the presence of a badge inside the passenger compartment. This detection is done by a request sent by the vehicle to the badge (s), followed by a response from the badges present.
- the vehicle uses a low frequency magnetic field (eg 125 kHz) to send its request. This type of magnetic field allows precise interior / exterior location due to the characteristic properties of low frequencies.
- the cabin computer incorporates a power amplifier which controls low-frequency antennas placed in the cabin of the vehicle.
- this low frequency amplifier in certain embodiments, requires a higher supply voltage than the voltage of the battery available in the vehicle.
- the computer includes a voltage booster circuit.
- This type of circuit is well known in the electronic field and uses a circuit switching a current in a choke.
- This type of assembly generates strong currents at frequencies close to that used for the magnetic field of the vehicle's "hands-free" system. These strong currents also radiate a magnetic field.
- this field presents locally (ie near the place where it is generated - in our case near the computer) a higher amplitude than that radiated by the antennas of the system itself. Consequently, this field (emitted by the voltage booster circuit) is a parasitic magnetic field which locally disturbs the good emission of the antennas internal to the vehicle and which locally covers the useful signal emitted by the passenger compartment computer and creates a zone of non-detection of the badge. inside the living space.
- a badge however well located inside the passenger compartment, can be considered by the vehicle as not being there. This is quite simply due to its non-response to the request made by the computer. Indeed if this request is parasitized it is not received by the badge which therefore does not respond. The magnetic radiation emitted by the voltage raising circuit thus disturbs the location of the badge inside the vehicle. To overcome this drawback, it would be possible to filter the currents generated by the computer using additional components. But these components are expensive. We therefore seek to overcome the parasitic magnetic field without using expensive components and without complicating the signal processing. To this end, the present invention proposes to mask the spurious signal with the useful signal of the system.
- the present invention relates to a method for masking a parasitic electromagnetic noise in a passenger compartment of a motor vehicle, said method being characterized in that it comprises the following step: - creation of a useful magnetic field by means of a current loop (20; 30), this useful magnetic field being adapted to locally superimpose the parasitic signal generated and having a radiation greater than that emitted by said parasitic field so as to cover this field and locally improve the signal ratio on noise.
- the step of creating the masking magnetic field consists in creating a current loop. This current loop is formed either by a printed circuit track supporting the voltage booster, or by a power cable from an interior antenna of the vehicle.
- the present invention also relates to a corresponding device.
- a useful magnetic field is created near the passenger compartment computer with the useful signal from the system.
- a track is used on the computer circuit board traversed by the current transmitted to the interior antennas of the vehicle.
- This track must have the form of a loop with a sufficient surface to generate the useful magnetic field capable of locally covering the parasitic signal.
- This loop must be traversed by the current sent to the interior antennas, since in this specific case, the system seeks to detect a badge inside the vehicle. It is therefore in this case that the parasitic noise generated by the voltage-raising circuit is annoying.
- the current loop is produced by one of the wires of the wiring of an indoor antenna.
- an electronic computer 10 intended to be placed in the passenger compartment of a vehicle comprises a generator 11 of carrier for example of 125 kHz intended to generate a signal for requesting the presence of a badge.
- This generator 11 receives a signal from request to be modulated 12 and sends a modulated request signal to an analog multiplexer 14 13.
- the multiplexer 14 makes it possible, in a manner known per se, to select the type of antenna 15 (interior or exterior for example) and sends the modulated signal to a voltage booster device 16 comprising an amplifier 17.
- This voltage booster is a conventional circuit using a circuit switching a current in a choke.
- the modulated and amplified signal is then transmitted to an external 18 or internal antenna 19.
- this voltage booster circuit generates an electromagnetic field (noise) parasitically locally (in the vicinity of the computer).
- a current loop 20 making it possible to locally generate a useful magnetic field covering the noise of the voltage booster circuit 16 is produced by a track of the printed circuit traversed by the signal delivered to the indoor antenna. Therefore the device according to the invention is adapted to issue a request to one (or more) badge (s), so as to detect its (their) presence (s). The badge receives this request even if it is near the computer because the masking field created by the current loop 20 is stronger (locally) than the stray field.
- the detection of the badge is made possible despite the parasitic radiation of the computer, without having to shield the computer or to filter its signal in a sophisticated and expensive manner.
- the creation of the useful magnetic field and the parasitic magnetic field is simultaneous. Consequently, the parasitic field no longer covers the badge detection request signal when the badge is placed near the computer.
- the disappearance of the badge non-detection zone near the computer does not require additional costly components or complex filtering of the signal.
- a simple loop carried out by a track of the computer makes it possible to mask the parasitic noise by creating a useful signal stronger than the parasitic noise and therefore by improving the signal to noise ratio locally.
- the current loop 30 according to the invention can be produced in the wiring of the indoor antenna 19, itself.
- this current loop 30 is produced on the wiring at the location where the parasitic signal is strongest.
- the purpose of this loop is to locally generate a masking magnetic field and to locally improve the signal to noise ratio.
- Such a loop is therefore effective if it is placed at the place where the signal is parasitized.
- This current loop is therefore suitable for masking noise whatever its origin.
- the sizing of the current loop (whatever the embodiment) is easy to carry out, it suffices simply to have a signal of sufficient intensity.
- the synchronization between the emission of the parasitic magnetic field and the magnetic field emitted by the current loop is automatic since these two fields are created simultaneously as soon as one activates the search for one (or more) badge (s) inside the vehicle.
- the present invention is not limited to the embodiments described above. Thus it is possible to mask any parasitic magnetic field by the realization of a current loop at the place where the parasitic magnetic field is strongest.
Abstract
The invention relates to a method of masking an unwanted electromagnetic noise generated by a motor vehicle computer (10). The inventive method is characterised in that it comprises the following step, namely: the creation of a magnetic field using a current loop (20), said magnetic field being adapted to superimpose locally the signal generated by the computer and having a radiation greater than that emitted by the electromagnetic noise, such as to cover said noise and locally improve the signal/noise ratio. The invention also relates to a corresponding device.
Description
Procédé de masquage d'un bruit électromagnétique parasite généré par un calculateur de véhicule automobile et dispositif correspondant La présente invention concerne un procédé de masquage d'un bruit électromagnétique parasite généré par un calculateur de véhicule automobile et un dispositif correspondant. Plus particulièrement il s'agit d'un calculateur placé dans l'habitacle du véhicule et adapté pour commander l'accès et le démarrage "mains libres" du véhicule. Le bruit parasite est quant à lui, généré lors de l'activation d'antennes internes du véhicule. Il est déjà connu de munir un véhicule automobile d'un système dit "mains libres". Un tel système permet au détenteur d'un badge de verrouiller ou de déverrouiller l'accès à son véhicule sans avoir à actionner de boutons de télécommande. En effet, dans un tel système, un dialogue en radio fréquence (ex 433 MHz) et/ou en basse fréquence (ex 125 kHz) s'établit entre un badge et le véhicule de telle sorte qu'à l'approche du badge, le véhicule détecte la présence de celui-ci et déverrouille le véhicule. De même lors de l'éloignement du badge le verrouillage du véhicule est commandé. Ce système mains libres peut être étendu à la fonction de démarrage du véhicule. Dans ce cas lorsque le badge est détecté à l'intérieur du véhicule, l'appui sur un bouton de démarrage provoque le démarrage du moteur. Un tel système d'accès et de démarrage "mains libres" nécessite donc de pouvoir localiser très précisément le (ou les) badge(s) par rapport au véhicule. A cet effet le véhicule est muni d'antennes (emettrice / réceptrice) tant à l'extérieur qu'à l'intérieur du véhicule. Le véhicule doit être en mesure notamment de détecter la présence d'un badge à l'intérieur de l'habitacle. Cette détection se fait par une requête envoyée par le véhicule vers le ou les badge(s), suivi d'une réponse des badges présents. Le véhicule utilise un champ magnétique basse fréquence (par ex 125 kHz) pour envoyer sa requête. Ce type de champs magnétique permet une localisation intérieure / extérieure précise du fait des propriétés caractéristiques des basses fréquences. Pour générer ce champ magnétique basses fréquences le calculateur habitacle intègre un amplificateur de puissance qui commande des antennes basses fréquences placées dans l'habitacle du véhicule. Or cet amplificateur basse fréquence, dans certains modes de réalisation, nécessite une tension d'alimentation plus élevée que la tension de la batterie disponible dans le véhicule.
Pour pallier cet inconvénient le calculateur comprend un circuit élévateur de tension. Ce type de circuit, est bien connu dans le domaine électronique et utilise un circuit commutant un courant dans une self. Ce type de montage génère de fort courants à des fréquences proches de celle utilisée pour le champ magnétique du système "mains libres" du véhicule. Ces forts courants rayonnent eux aussi un champ magnétique. Or ce champ présente localement (c'est à dire près de l'endroit où il est généré - dans notre cas à proximité du calculateur) une plus forte amplitude que celui rayonné par les antennes du système lui-même. En conséquence ce champ (émis par le circuit élévateur de tension) est un champ magnétique parasite qui perturbe localement la bonne émission des antennes internes au véhicule et qui couvre localement le signal utile émis par le calculateur habitacle et crée une zone de non détection du badge à l'intérieur de l'habitable. Ainsi, un badge, pourtant bien situé à l'intérieur de l'habitacle, peut être considéré par le véhicule comme n'y étant pas. Ceci tout simplement en raison de sa non-réponse à la requête émise par le calculateur. En effet si cette requête est parasitée elle n'est pas reçue par le badge qui ne réponds donc pas. Le rayonnement magnétique émis par le circuit élévateur de tension perturbe ainsi la localisation du badge à l'intérieur du véhicule. Pour pallier cet inconvénient il serait possible de filtrer les courants générés par le calculateur en utilisant des composants supplémentaires. Mais ces composants sont coûteux. On cherche donc à s'affranchir du champ magnétique parasite sans employer de composants coûteux et sans complexifier le traitement du signal. A cet effet la présente invention propose de masquer le signal parasite avec le signal utile du système. Ainsi la présente invention concerne un procédé de masquage d'un bruit électromagnétique parasite dans un habitacle de véhicule automobile, le dit procédé étant caractérisé en ce qu'il comporte l'étape suivante: - création d'un champ magnétique utile au moyen d'une boucle de courant (20; 30), ce champs magnétique utile étant adapté pour se superposer localement au signal parasite généré et ayant un rayonnement supérieur à celui émis par le dit champ parasite de sorte à couvrir ce champ et à améliorer localement le rapport signal sur bruit.
On notera que l'étape de création du champ magnétique de masquage consiste à créer une boucle de courant. Cette boucle de courant est constituée soit par une piste du circuit imprimé supportant l'élévateur de tension, soit par un câble d'alimentation d'une antenne intérieure du véhicule. La présente invention concerne également un dispositif correspondant. Ainsi pour masquer le signal parasite on crée un champ magnétique utile à proximité du calculateur habitacle avec le signal utile du système. Plutôt que d'utiliser une antenne supplémentaire, on utilise une piste sur le circuit imprimé du calculateur parcouru par le courant transmis aux antennes intérieures du véhicule. Cette piste doit avoir la forme d'une boucle d'une surface suffisante pour générer le champ magnétique utile capable de couvrir localement le signal parasite. Cette boucle doit être parcourue par le courant envoyé aux antennes intérieures, puisque dans ce cas précis, le système cherche à détecter un badge à l'intérieur du véhicule. C'est donc dans ce cas là, que le bruit parasite généré par le circuit élévateur de tension est gênant. Selon un second mode de réalisation, la boucle de courant est réalisée par l'un des fils du câblage d'une antenne intérieure. La boucle de courant créée par le câblage de l'antenne masque ainsi localement le bruit parasite du calculateur mais peut être également utilisée pour masquer tout autre bruit généré par l'électronique du véhicule. De préférence la boucle est réalisée sur le câblage à l'endroit où le signal parasite est le plus fort. D'autres objets, caractéristiques et avantages de la présente invention ressortiront d'ailleurs de la description qui suit, à titre d'exemple non limitatif, en référence aux dessins annexés dans lesquels: - La figure 1 représente, de manière schématique, un dispositif de masquage selon un premier mode de réalisation de l'invention, et - La figure 2 représente, de manière schématique, un dispositif de masquage selon un second mode de réalisation de l'invention. Selon le mode de réalisation représenté à la figure 1 , un calculateur électronique 10 destiné à être placé dans l'habitacle d'un véhicule comporte un générateur 11 de porteuse par exemple de 125 kHz destiné à générer un signal de requête de la présence d'un badge. Ce générateur 11 reçoit un signal de
requête à moduler 12 et envoie vers un multiplexeur analogique 14 un signal de requête modulé 13. Le multiplexeur 14 permet, de manière connue en soi, de sélectionner le type d'antennes 15 (intérieure ou extérieure par exemple) et envoie le signal modulé vers un dispositif élévateur de tension 16 comportant un amplificateur 17. Cet élévateur de tension est un circuit classique utilisant un circuit commutant un courant dans une self. Le signal modulé et amplifié est ensuite transmis vers une antenne extérieure 18 ou intérieure 19. De manière connue ce circuit élévateur de tension génère un champ électromagnétique (bruit) parasite localement (au voisinage du calculateur). Selon l'invention une boucle de courant 20 permettant de générer localement un champ magnétique utile couvrant le bruit du circuit élévateur de tension 16 est réalisée par une piste du circuit imprimé parcourue par le signal délivré à l'antenne intérieure. De ce fait le dispositif selon l'invention est adapté pour émettre une requête vers un (ou des) badge(s), de manière à détecter sa (leurs) présence(s). Le badge reçoit cette requête même s'il se trouve à proximité du calculateur car le champ de masquage créé par la boucle de courant 20 est plus fort (localement) que le champ parasite. De ce fait la détection du badge est rendue possible malgré le rayonnement parasite du calculateur, sans avoir à blinder le calculateur ou à filtrer son signal de manière sophistiquée et onéreuse. On notera que la création du champ magnétique utile et du champ magnétique parasite est simultannée. En conséquence le champ parasite ne couvre plus le signal de requête de détection du badge lorsque le badge est placé près du calculateur. Dés lors il n'existe plus de zone de non détection du badge à proximité du calculateur. Avantageusement la disparition de la zone de non détection du badge à proximité du calculateur ne nécessite pas de composants coûteux supplémentaires ni de filtrage complexe du signal. Une simple boucle réalisée par une piste du calculateur permet de masquer le bruit parasite en créant un signal utile plus fort que le bruit parasite et donc en améliorant le rapport signal sur bruit localement. L'invention permet donc de résoudre à moindre coût le problème de la non détection du badge à proximité du calculateur.
Selon un second mode de réalisation, schématisé à la figure 2, la boucle de courant 30 selon l'invention peut être réalisée dans le câblage de l'antenne intérieure 19, elle-même. Avantageusement cette boucle de courant 30 est réalisée sur le câblage à l'endroit où le signal parasite est le plus fort. En effet le but de cette boucle est de générer localement un champs magnétique de masquage et d'améliorer localement le rapport signal sur bruit. Une telle boucle est donc efficace si elle se trouve placée à l'endroit où le signal est parasité. Cette boucle de courant est donc adaptée pour masquer un bruit quelle qu'en soit sa provenance. Le dimensionnement de la boucle de courant (quel que soit le mode de réalisation) est facile à réaliser, il suffit simplement d'avoir un signal d'intensité suffisante. On notera également que la synchronisation entre l'émission du champ magnétique parasite et le champ magnétique émis par la boucle de courant est automatique puisque ces deux champs sont créés simultanément dés lors que l'on active la recherche d'un (ou des) badge(s) à l'intérieur du véhicule. Bien entendu, la présente invention n'est pas limitée aux modes de réalisations ci-dessus décrits. Ainsi il est possible de masquer tout champ magnétique parasite par la réalisation d'une boucle de courant à l'endroit où le champ magnétique parasite est le plus fort.
The present invention relates to a method for masking parasitic electromagnetic noise generated by a motor vehicle control unit and a corresponding device. More particularly, it is a computer placed in the passenger compartment of the vehicle and suitable for controlling access and "hands-free" starting of the vehicle. Interference noise is generated when the vehicle's internal antennas are activated. It is already known to provide a motor vehicle with a so-called "hands-free" system. Such a system allows the holder of a badge to lock or unlock access to his vehicle without having to actuate remote control buttons. Indeed, in such a system, a radio frequency (eg 433 MHz) and / or low frequency (eg 125 kHz) dialogue is established between a badge and the vehicle so that when the badge is approached, the vehicle detects the presence of the latter and unlocks the vehicle. Likewise when the badge is removed, the vehicle is locked. This hands-free system can be extended to the vehicle starting function. In this case when the badge is detected inside the vehicle, pressing a start button causes the engine to start. Such a "hands-free" access and starting system therefore requires being able to very precisely locate the badge (s) relative to the vehicle. For this purpose the vehicle is provided with antennas (transmitter / receiver) both outside and inside the vehicle. The vehicle must in particular be able to detect the presence of a badge inside the passenger compartment. This detection is done by a request sent by the vehicle to the badge (s), followed by a response from the badges present. The vehicle uses a low frequency magnetic field (eg 125 kHz) to send its request. This type of magnetic field allows precise interior / exterior location due to the characteristic properties of low frequencies. To generate this low-frequency magnetic field, the cabin computer incorporates a power amplifier which controls low-frequency antennas placed in the cabin of the vehicle. However, this low frequency amplifier, in certain embodiments, requires a higher supply voltage than the voltage of the battery available in the vehicle. To overcome this drawback, the computer includes a voltage booster circuit. This type of circuit is well known in the electronic field and uses a circuit switching a current in a choke. This type of assembly generates strong currents at frequencies close to that used for the magnetic field of the vehicle's "hands-free" system. These strong currents also radiate a magnetic field. However, this field presents locally (ie near the place where it is generated - in our case near the computer) a higher amplitude than that radiated by the antennas of the system itself. Consequently, this field (emitted by the voltage booster circuit) is a parasitic magnetic field which locally disturbs the good emission of the antennas internal to the vehicle and which locally covers the useful signal emitted by the passenger compartment computer and creates a zone of non-detection of the badge. inside the living space. Thus, a badge, however well located inside the passenger compartment, can be considered by the vehicle as not being there. This is quite simply due to its non-response to the request made by the computer. Indeed if this request is parasitized it is not received by the badge which therefore does not respond. The magnetic radiation emitted by the voltage raising circuit thus disturbs the location of the badge inside the vehicle. To overcome this drawback, it would be possible to filter the currents generated by the computer using additional components. But these components are expensive. We therefore seek to overcome the parasitic magnetic field without using expensive components and without complicating the signal processing. To this end, the present invention proposes to mask the spurious signal with the useful signal of the system. Thus, the present invention relates to a method for masking a parasitic electromagnetic noise in a passenger compartment of a motor vehicle, said method being characterized in that it comprises the following step: - creation of a useful magnetic field by means of a current loop (20; 30), this useful magnetic field being adapted to locally superimpose the parasitic signal generated and having a radiation greater than that emitted by said parasitic field so as to cover this field and locally improve the signal ratio on noise. It will be noted that the step of creating the masking magnetic field consists in creating a current loop. This current loop is formed either by a printed circuit track supporting the voltage booster, or by a power cable from an interior antenna of the vehicle. The present invention also relates to a corresponding device. Thus, to mask the parasitic signal, a useful magnetic field is created near the passenger compartment computer with the useful signal from the system. Rather than using an additional antenna, a track is used on the computer circuit board traversed by the current transmitted to the interior antennas of the vehicle. This track must have the form of a loop with a sufficient surface to generate the useful magnetic field capable of locally covering the parasitic signal. This loop must be traversed by the current sent to the interior antennas, since in this specific case, the system seeks to detect a badge inside the vehicle. It is therefore in this case that the parasitic noise generated by the voltage-raising circuit is annoying. According to a second embodiment, the current loop is produced by one of the wires of the wiring of an indoor antenna. The current loop created by the antenna wiring thus locally masks parasitic noise from the computer, but can also be used to mask any other noise generated by the vehicle electronics. Preferably the loop is made on the wiring at the point where the parasitic signal is strongest. Other objects, characteristics and advantages of the present invention will also emerge from the description which follows, by way of nonlimiting example, with reference to the appended drawings in which: - Figure 1 shows, schematically, a device masking according to a first embodiment of the invention, and - Figure 2 shows, schematically, a masking device according to a second embodiment of the invention. According to the embodiment represented in FIG. 1, an electronic computer 10 intended to be placed in the passenger compartment of a vehicle comprises a generator 11 of carrier for example of 125 kHz intended to generate a signal for requesting the presence of a badge. This generator 11 receives a signal from request to be modulated 12 and sends a modulated request signal to an analog multiplexer 14 13. The multiplexer 14 makes it possible, in a manner known per se, to select the type of antenna 15 (interior or exterior for example) and sends the modulated signal to a voltage booster device 16 comprising an amplifier 17. This voltage booster is a conventional circuit using a circuit switching a current in a choke. The modulated and amplified signal is then transmitted to an external 18 or internal antenna 19. In a known manner, this voltage booster circuit generates an electromagnetic field (noise) parasitically locally (in the vicinity of the computer). According to the invention a current loop 20 making it possible to locally generate a useful magnetic field covering the noise of the voltage booster circuit 16 is produced by a track of the printed circuit traversed by the signal delivered to the indoor antenna. Therefore the device according to the invention is adapted to issue a request to one (or more) badge (s), so as to detect its (their) presence (s). The badge receives this request even if it is near the computer because the masking field created by the current loop 20 is stronger (locally) than the stray field. Therefore the detection of the badge is made possible despite the parasitic radiation of the computer, without having to shield the computer or to filter its signal in a sophisticated and expensive manner. It will be noted that the creation of the useful magnetic field and the parasitic magnetic field is simultaneous. Consequently, the parasitic field no longer covers the badge detection request signal when the badge is placed near the computer. As a result, there is no longer a non-detection zone for the badge near the computer. Advantageously, the disappearance of the badge non-detection zone near the computer does not require additional costly components or complex filtering of the signal. A simple loop carried out by a track of the computer makes it possible to mask the parasitic noise by creating a useful signal stronger than the parasitic noise and therefore by improving the signal to noise ratio locally. The invention therefore makes it possible to solve the problem of non-detection of the badge near the computer at a lower cost. According to a second embodiment, shown diagrammatically in FIG. 2, the current loop 30 according to the invention can be produced in the wiring of the indoor antenna 19, itself. Advantageously, this current loop 30 is produced on the wiring at the location where the parasitic signal is strongest. The purpose of this loop is to locally generate a masking magnetic field and to locally improve the signal to noise ratio. Such a loop is therefore effective if it is placed at the place where the signal is parasitized. This current loop is therefore suitable for masking noise whatever its origin. The sizing of the current loop (whatever the embodiment) is easy to carry out, it suffices simply to have a signal of sufficient intensity. It will also be noted that the synchronization between the emission of the parasitic magnetic field and the magnetic field emitted by the current loop is automatic since these two fields are created simultaneously as soon as one activates the search for one (or more) badge (s) inside the vehicle. Of course, the present invention is not limited to the embodiments described above. Thus it is possible to mask any parasitic magnetic field by the realization of a current loop at the place where the parasitic magnetic field is strongest.
Claims
1. Procédé de masquage d'un bruit électromagnétique parasite généré par un calculateur (10) de véhicule automobile, le dit procédé étant caractérisé en ce qu'il comporte l'étape suivante:1. A method for masking a parasitic electromagnetic noise generated by a computer (10) of a motor vehicle, said method being characterized in that it comprises the following step:
- création d'un champ magnétique utile, ce champs magnétique étant adapté pour se superposer localement au bruit électromagnétique parasite généré par le calculateur et ayant un rayonnement supérieur à celui émis par le bruit électromagnétique de sorte à couvrir ce bruit et à améliorer localement le rapport signal sur bruit.creation of a useful magnetic field, this magnetic field being adapted to locally superimpose the parasitic electromagnetic noise generated by the computer and having a radiation greater than that emitted by the electromagnetic noise so as to cover this noise and locally improve the ratio signal to noise.
2. Procédé de masquage selon la revendication 1 , caractérisé en ce que le champ magnétique utile est créé au moyen d'une boucle de courant (20, 30).2. Masking method according to claim 1, characterized in that the useful magnetic field is created by means of a current loop (20, 30).
3. Procédé selon la revendication 2, caractérisé en ce que la boucle de courant (20) est constituée par une piste de circuit imprimé et est adaptée pour masquer un bruit parasite en provenance d'un calculateur.3. Method according to claim 2, characterized in that the current loop (20) is constituted by a printed circuit track and is adapted to mask parasitic noise coming from a computer.
4. Procédé selon la revendication 2, caractérisé en ce que la boucle de courant (30) est réalisée sur un câble d'alimentation d'une antenne intérieure (19) du véhicule et est adaptée pour masquer un bruit quelle qu'en soit sa provenance.4. Method according to claim 2, characterized in that the current loop (30) is formed on a power cable of an interior antenna (19) of the vehicle and is adapted to mask a noise whatever its origin.
5. Dispositif de masquage de bruit magnétique mettant en œuvre le procédé selon l'une quelconque des revendications précédentes, le dit dispositif comportant un composant générant un bruit magnétique parasite, le dit dispositif étant caractérisé en ce qu'il comporte:5. Magnetic noise masking device implementing the method according to any one of the preceding claims, said device comprising a component generating a parasitic magnetic noise, said device being characterized in that it comprises:
- une boucle de courant (20; 30) générant un champ magnétique utile masquant le dit bruit magnétique.- a current loop (20; 30) generating a useful magnetic field masking said magnetic noise.
6. Dispositif selon la revendication 5, caractérisé en ce que le bruit parasite est émis lors de l'envoie d'une requête (13) en basse fréquence par le véhicule vers des dispositifs portables (appelés badges) cette requête étant émise par des antennes intérieures (19) au véhicule et en ce que la boucle de courant (20) est directement constituée par une piste de circuit imprimé.6. Device according to claim 5, characterized in that the parasitic noise is emitted during the sending of a low frequency request (13) by the vehicle to portable devices (called badges) this request being sent by antennas internal (19) to the vehicle and in that the current loop (20) is directly constituted by a printed circuit track.
7. Dispositif selon la revendication 5, caractérisé en ce que le bruit parasite est émis lors de l'envoie d'une requête (13) en basse fréquence par le véhicule vers des dispositifs portables (appelés badges) cette requête étant émise par des antennes intérieures (19) au véhicule et en ce que la boucle de courant (30) est directement réalisée sur le câble alimentant les antennes intérieures (19). 7. Device according to claim 5, characterized in that the parasitic noise is emitted during the sending of a low frequency request (13) by the vehicle to portable devices (called badges) this request being sent by antennas internal (19) to the vehicle and in that the current loop (30) is directly formed on the cable supplying the internal antennas (19).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR0314328A FR2863424B1 (en) | 2003-12-08 | 2003-12-08 | METHOD OF MASKING A PARASITIC ELECTROMAGNETIC NOISE GENERATED BY A MOTOR VEHICLE CALCULATOR AND CORRESPONDING DEVICE |
| FR0314328 | 2003-12-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2005055477A1 true WO2005055477A1 (en) | 2005-06-16 |
Family
ID=34586349
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP2004/013835 WO2005055477A1 (en) | 2003-12-08 | 2004-12-06 | Method of masking an unwanted electromagnetic noise generated by a motor vehicle computer and corresponding device |
Country Status (2)
| Country | Link |
|---|---|
| FR (1) | FR2863424B1 (en) |
| WO (1) | WO2005055477A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080272246A1 (en) * | 2007-05-02 | 2008-11-06 | Samuel Robert Mollet | Methods and systems for active noise cancellation |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20010000960A1 (en) * | 1998-05-18 | 2001-05-10 | Dettloff Wayne D. | Systems and methods for wirelessly projecting power using multiple in-phase current loops |
| FR2814130A1 (en) * | 2000-09-18 | 2002-03-22 | Valeo Electronique | Automobile vehicle with hands-free access system, uses circuit between vehicle battery and driver of antenna fitted below vehicle roof to raise voltage from 12 V to 42 V |
| FR2823908A1 (en) * | 2001-04-19 | 2002-10-25 | Siemens Automotive Sa | ANTENNA CONTROL PROCESS |
| US6567050B1 (en) * | 2001-12-17 | 2003-05-20 | Briggs James B | Loop antenna compensator |
-
2003
- 2003-12-08 FR FR0314328A patent/FR2863424B1/en not_active Expired - Fee Related
-
2004
- 2004-12-06 WO PCT/EP2004/013835 patent/WO2005055477A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20010000960A1 (en) * | 1998-05-18 | 2001-05-10 | Dettloff Wayne D. | Systems and methods for wirelessly projecting power using multiple in-phase current loops |
| FR2814130A1 (en) * | 2000-09-18 | 2002-03-22 | Valeo Electronique | Automobile vehicle with hands-free access system, uses circuit between vehicle battery and driver of antenna fitted below vehicle roof to raise voltage from 12 V to 42 V |
| FR2823908A1 (en) * | 2001-04-19 | 2002-10-25 | Siemens Automotive Sa | ANTENNA CONTROL PROCESS |
| US6567050B1 (en) * | 2001-12-17 | 2003-05-20 | Briggs James B | Loop antenna compensator |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2863424A1 (en) | 2005-06-10 |
| FR2863424B1 (en) | 2008-08-15 |
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