EP0909112A1 - Wireless system with digital transmission for loudspeakers - Google Patents

Abstract

A digital audio signal is compressed, converted to serial, passed to a quadrature phase modulator (101) and transmitted to a receiver (RX), attached to a loudspeaker (HP). Serial conversion adds protocol information, destination address, loudspeaker control information, and encryption key. The receiver checks the packet address and carries out decryption if it matches its own.

Description

The present invention relates to a wireless transmission system digital speaker.

Wireless speaker systems are known in which a analog audio signal is converted to frequency modulation signal, this frequency modulated signal being transmitted over power lines AC from a home network. The signal received by the network domestic product is then converted back to an audio signal after extracting the modulated frequency signal.

Such teaching is notably disclosed by U.S. patent 4 829,570. This patent also contemplates the use of a device for compression to allow compression of analog signals delivered by a compact disc player, whose wide dynamic range requires a very wide bandwidth to allow transmission in frequency modulation. Broadband and large deviations pose many problems which are solved in this document by the use of a compressor circuit to reduce the total dynamic range audio signal. This document already allows us to become aware of a first difficulty which is the limitation of stereophonic systems in particular using frequency modulation and operating with analog systems such as variable frequency oscillators.

When you want to go from simple stereophonic quality to "Digital CD" type stereo quality, the amount of information to be transmit is such that one is very quickly limited in frequency modulation by bandwidth.

Finally, this type of system taught by U.S. Patent 4,829,570 is acceptable for private use on the home network a personal home but can be difficult to set up in a building or even less in communities or complexes commercial. Indeed, the music broadcast on the power network will picked up at the same time by all installed and connected speakers to the network. This poses a copyright issue and it is therefore desirable to provide a device which makes it possible to avoid a diffusion widespread.

Finally, such a device requires, in order to have the two channels stereophonic, to provide a first carrier frequency for the first channel and a second carrier frequency for the second channel. These frequencies will have to be selected according to very precise conditions, this which will also limit the possibilities of bandwidth.

A first object of the invention is to propose a wireless system with digital transmission for loudspeakers which allows the diffusion of digital compact disc quality stereo signals and / or the remote control.

• des moyens de compression du fichier représentatif du signal numérique audio de type "Compact disque", un dispositif d'émission comportant des moyens de transformation de ce signal compressé en signal série circulant par paquets à destination d'un circuit modulateur à quadrature de phases et des moyens de transmettre les signaux sortant du circuit modulateur à quadrature de phases au réseau domestique d'alimentation en électricité ;
• un dispositif de réception comportant des moyens de branchement sur ce réseau domestique et d'extraire du signal d'alimentation en électricité par un démodulateur à quadrature de phases les paquets d'informations véhiculant le signal numérique audio pour le transformer en un signal numérique parallélisé envoyé vers un circuit de décompression ;
• des moyens de transformer les signaux numériques décompressés en un signal analogique destiné à alimenter un haut-parleur après amplification adéquate.

This first goal is achieved by the fact that the digital transmission wireless system for loudspeakers comprises:

• means for compressing the file representative of the digital audio signal of the "Compact disc" type, a transmission device comprising means for transforming this compressed signal into a serial signal circulating in packets intended for a phase quadrature modulator circuit and means for transmitting the signals leaving the phase quadrature modulator circuit to the domestic electricity supply network;
• a reception device comprising means of connection to this home network and of extracting from the power supply signal by a quadrature phase demodulator the information packets carrying the digital audio signal to transform it into a parallelized digital signal sent to a decompression circuit;
• means for transforming the decompressed digital signals into an analog signal intended to supply a loudspeaker after adequate amplification.

A second goal is to allow the emission of several signals to different speakers.

This object is achieved by the fact that the serialization means include means for inserting into the serialized signal packets a destination address;
and in that the reception means comprise means for comparing the address appearing in the received packet with the address specific to the reception device to which the loudspeaker is connected.

According to another particular feature, the serialization device comprises means for multiplexing multiple frames of digital files representative of a different audio signal to different addresses.

Another object of the invention is to propose a system which allows to ensure that copyright cannot be defrauded.

This third goal is achieved by the fact that the transmission circuits have an encryption circuit and the receiving device connected includes a decryption circuit using a secret key stored in the memory of the deserialization circuit.

According to another particular feature, the information of the digital signal are serialized according to a protocol comprising a first part constitutive of protocol information, a second constitutive part of the recipient's address, a third part constituting the signal digital or multiplexed digital signals, and a fourth part constituting the end of protocol information.

In another feature, the protocol includes a fifth component of the speaker control information.

In another feature, the protocol includes a sixth component of at least one encryption key.

According to another particular feature, the system includes means for include control commands allowing individual adjustment of each loudspeaker, in the serial signal circulating in packets.

According to another feature, the system
comprises means for converting an analog signal into a digital signal, arranged upstream of the means for compressing the file representative of the audio signal, when the audio signal to be transmitted is of the analog type.

• la figure 1 représente une vue schématique du circuit électronique permettant la mise en oeuvre de l'invention ;
• la figure 2 représente une vue schématique d'un système audiovisuel de type "Juke-box" dans lequel le dispositif de l'invention peut être utilisé.

Other characteristics and advantages of the present invention will appear more clearly on reading the description below made with reference to the accompanying drawings in which:

• FIG. 1 represents a schematic view of the electronic circuit allowing the implementation of the invention;
• FIG. 2 represents a schematic view of an audiovisual system of the "jukebox" type in which the device of the invention can be used.

The invention will now be described in conjunction with FIG. 1 on which reference (13) designates the two conductors of a network domestic supply of electrical energy to a building or premises intended to accommodate a public or a community such as for example a bar, a department store, a sports center, etc .... On this network power supply device is connected an emission device (10) comprising the primary winding of a first transformer (108) which delivers by its secondary winding through a diode rectifier circuit a power signal to a power circuit (100) which extracts from the signal of rectified AC power, the signals necessary to the supply of the various circuits of the device. In parallel, on the primary of this first transformer (108) is connected a second transformer (109) whose secondary winding is supplied through a transistor by a phase quadrature modulation circuit (101). This circuit (101) is supplied with voltage by the circuit (100) and receives from a microcontroller (102) packet streams (P1, P2) of data representing information digital serialized according to a protocol (P) shown below. This protocol (P) comprises a first part (IP) constituting the information protocol, a second part (AD) constituting the address of the recipient or the addresses of each recipient, a possible third part (IC) constituting the speaker control information, a possible fourth part (CE) constituting a key encryption or several keys, each for an address, a fifth part (ANS) constituting the digital audio signal or multiplexed audio signals, each signal being associated with one of the addresses of the recipient and finally, a sixth part (IFP) constituting the information end of protocol.

The signals are modulated in phase quadrature by the circuit (101) on a carrier, located between 200 and 300 kHz and are superimposed on the AC signal from the mains via the transformer (109). The digital audio signals from the audio source after compression, represent a digital bit rate of 128 kilo bits per second and are processed by the microcontroller (102) to be sent in packets successive according to the protocol (EP) explained above.

The microcontroller program (102) can be arranged to multiplexing multiple audio sources allowing for example, to send a piece of classical music to a first speaker while sending a song at the same time jazz music to a second speaker, each with a specific address and its own decryption key.

In this case, the device (10) addresses one or more frames to a user identified by a card or a box (11) connected to the loudspeaker. The transmitting device (10) and the receiving device (s) (11) are not connected together only through the electrical conductors of the network domestic power supply.

Finally, the microcontroller operating program (102) will allow upon receipt of orders sent by a box of remote control (12), for example transmitting a wave signal at destination a sensor (1020), to include the commands thus generated by this box (12) in the package, so as to constitute the control information of the loud speaker. This control information allows individual adjustment each speaker by adjusting the right channel, the left channel, the bass, treble, volume, etc .....

When you want to protect the audio information carried on the home network, so that copyright can be collected and prevent the same piece of music from being heard by people not having paid the copyright, we will add in the device a encryption circuit (103) placed between the compression circuit (104) and the microcontroller (102). If the source of the musical signals is not not of the "Digital" type, a converter is added to the device analog digital (106) receiving at its input the output signals an analog amplifier (107) which receives the audio signals analog.

The receiving device (11) is constituted as above by a first transformer (118) allowing using a circuit rectifier, to supply a supply circuit (110) intended to generate the supply signals necessary for the operation of the various circuits of the receiving device (11). A second transformer (119) connected on the primary of the first, using a decoupling capacity, feeds a phase quadrature demodulator (111) which provides on its output serial protocol signals and protocol packets to a microcontroller (112) which transforms these serial signals into parallel signals to a decryption circuit (113), the output of which is connected to a decompression circuit (114). The output of the decompression circuit (114) is itself connected to a digital conversion circuit analog (115), the output of which is intended to supply a loudspeaker (HP). Compression and decompression circuits by an amplifier (116) apply a level 3 "MPEG" algorithm and the encryption (103) and decryption (113) circuit implement a "MMPP" (MultiMedia Protection Protocol) type algorithm.

The memory of the microcontroller (112) of the housing (11) is loaded with the identification address which allows you to compare your address, to the address received in the packet to identify whether the digital information audio are intended for it or are intended for another speaker. Of even, the memory of the microcontroller is loaded during initialization or at manufacturing with a decryption key. Loading during initialization with the decryption key can be done using the fourth protocol area.

Analog to digital converter circuits (CAN / or DAC) encryption compression and amplification of the transmitting device (10) can be realized, for example, by a digital signal processor marketed by MOTOROLA under the reference 563XX and commonly called "D.S.P. (Digital Signal Processor)".

Similarly, the decryption, decompression and digital to analog conversion of the receiving device (11) can be realized in a digital signal processor marketed by MOTOROLA under the reference 563XX and commonly called "D.S.P. (Digital Signal Processor) ".

• compatibilité avec le bus local Vesa,
• antémémoire du processeur : 256 kO,
• ports série et parallèle de haute performance,
• adaptateur graphique type SVGA à microprocesseur,
• contrôleur de bus type SCSl/2,
• mémoire vive RAM statique auto-alimentéé.

It is thus possible, thanks to such a device, to allow the installation of multiple loudspeakers in different premises provided that they are supplied by the same phase of the network to which the transmission device (10) will be connected. This transmission device (10) must firstly be connected to a source of audio signals which may for example be the digital output of a compact disc player or the digital output of a hard drive of a juke- box such as that described in FIG. 2 and corresponding to PCT patent application FR 95 01333 published under the number WO 96/12 256 and on the other hand to the conductors of the electrical supply network of the building or of the premises. The jukebox of FIG. 2 consists of a central unit (1), a microprocessor which is a system compatible with the high performance PC. The choice during implementation fell on a system of the "lntel 80486 DX / 2" type which has storage means and the following characteristics:

• compatibility with the local Vesa bus,
• processor cache: 256 kB,
• high performance serial and parallel ports,
• SVGA graphics adapter with microprocessor,
• bus controller type SCSl / 2,
• self-powered static RAM.

Any other central unit with equivalent performance or higher could be used in the invention.

This central unit controls and manages a control circuit for sound (5), a telecommunication control circuit (4), a circuit (3) input control circuit, a memory control circuit (2) earth, a circuit (6) for controlling the display means. The visualization means consist mainly of a video monitor (62) 14 inch (35.56 cm) flat screen without type interlacing SVGA high resolution and low radiation, this monitor is used for image reproduction (for example, album covers music selections), graphics, or video clips.

Mass storage means (21) using discs high speed and high capacity "SCSl" hard drives are associated with storage means already present in the microprocessor device. These means are used to store digital audiovisual information and compressed.

A high speed telecommunications modem adapter (41) 28.8 kbps is integrated to authorize the link with a distribution network audiovisual information controlled by a central server.

To reproduce the sound information of the selections musical systems, the system includes speakers (54) receiving the signal amplifier-tuner (53) connected to an electronic circuit (5) of the type "Music synthesizer" designed to support a large number of input sources while providing output with a quality of "CD" type (compact disc), such as, for example, the audio adapter microprocessor-based multimedia, "Sound Blaster" card type SBP32AWE from Creative Labs Inc on which two memory buffers (56, 57) are added for the purpose explained later.

Likewise, the display means control circuit also includes two buffer memories (66, 67) for the stated purpose later.

A thermally regulated 240 watt ventilated power supply provides energy to the system. This power supply is protected against overcurrents and overshoots.

The audiovisual reproduction system manages, through its input controller circuit (3), a touch screen (33) "lntelli Touch" of 14 inches (35.56 cm) from Elo Touch Systems Inc., which includes a panel for coating the glass using "advanced surface wave technology" as well as an "AT" type bus controller. This touch screen allows, after have displayed on the video monitor (62) or the screen of a television set (61), various selection information used by customers as well as selection information used by customers, as well as information of orders and management control used by the manager or the system owner. It is also used for maintenance purposes in combination with an external keyboard (34) which can be connected to the system which has a keyboard connector for this, controlled by a key lock (32) through the interface circuit (3).

• d'une télécommande infrarouge de chez Mind Path Technologies Inc., émetteur qui possède 15 touches de commande pour le système à microprocesseur et 8 touches de commande pour dispositif de projection,
• d'un récepteur infrarouge avec adaptateur série de chez Mind Path Technologies Inc.

The input circuit (3) also interfaces with the remote control system (31) consisting for example:

• an infrared remote control from Mind Path Technologies Inc., a transmitter that has 15 control keys for the microprocessor system and 8 control keys for the projection device,
• of an infrared receiver with serial adapter from Mind Path Technologies Inc.

A royalty payment system (35) from National Rejectors Inc. is also connected to the input interface circuit (3). It is also possible to use any other device which allows the reception of any method of payment by coins, tickets, tokens, magnetic cards to chips or combination of means of payment.

To house the system, a chassis or frame is also provided. steel with customizable exterior fittings.

In addition to these elements, a wireless microphone (55) is connected to the sound controller (5), which turns it into a powerful system of public announcements and information or possibly in a karaoke machine. Likewise, a speaker system wireless can be used by the system.

• la commande marche-arrêt du microphone,
• la commande de mise en sourdine des haut-parleurs,
• la commande de contrôle de volume sonore,
• la commande d'annulation de la sélection musicale en train d'être écoutée.

The remote control assembly (31) allows the manager, for example from behind the bar, to access and control various commands such as:

• microphone on-off control,
• the loudspeaker mute command,
• sound volume control,
• the command to cancel the musical selection currently being listened to.

Two buffers (56, 57) are associated with the sound controller circuit (5) to allow each to store information in an alternative manner corresponding to a quarter of a second of sound. Similarly, two buffers (66, 67) are associated with the video controller circuit (6) each capable and alternatively to memorize a tenth of a second of images. Finally, a respective buffer (46, 36, 26) is associated with each of the controller circuits communication (4), input interface (3) and storage (2).

The digitized and compressed audiovisual data are stored in the storage means (21).

This information is transmitted through the unit central (1) to the map (105) on which the elements have been added corresponding to the circuit (10), the encryption circuit (103) being directly connected to the buffer circuits (56, 57) in the event that the information is already compressed, either by a first connector (1021), avoiding the circuit encryption (103), if the information is already encrypted or has not need to be, either by a second connector (1031), using the circuit encryption (103), if the information is to be encrypted. In the case where the information is not compressed, we will connect the buffers (56, 57) to a third connector (1041) so as to use the circuit compression.

Thus, by connecting the output of the transformer (108) to the sector, by connecting the receiving circuits (11) in different places on the sector, supply different remote speakers, in addition to loudspeakers normally provided in the jukebox system (54). This will allow good quality sound diffusion in different premises while by ensuring that the manager can adjust the volumes according to the local or according to the provisions of the loudspeakers.

In the case where the invention is used on another device such as compact disc player, radio for reception of specialized channels, etc ...., it is possible to equip the payment device using one of the payment methods mentioned above for the jukebox application which as for the jukebox will not allow the operation of the device receipt only once the fee has been paid and for the duration provided for the royalty fee. This duration is determined by a clock associated with the receiving device.

Other modifications within the reach of those skilled in the art make also part of the spirit of the invention.

Claims (9)

Wireless digital transmission system for loudspeakers comprising: means for compressing the file representative of the digital audio signal of the "Compact disc" type, a transmission device comprising means for transforming this compressed signal into a serial signal circulating in packets intended for a phase quadrature modulator circuit and means for transmitting the signals leaving the phase quadrature modulator circuit to the domestic electricity supply network; a reception device comprising means of connection to this home network and of extracting from the power supply signal by a quadrature phase demodulator the information packets carrying the digital audio signal to transform it into a parallelized digital signal sent to a decompression circuit; means for transforming the decompressed digital signals into an analog signal intended to supply a loudspeaker after adequate amplification. Wireless digital transmission system for loudspeakers according to claim 1, characterized in that the serialization means include means for inserting a destination address in the serialized signal packets;
and in that the reception means comprise means for comparing the address appearing in the received packet with the address specific to the reception device to which the loudspeaker is connected. Wireless system with digital transmission for loudspeakers according to claim 1 or 2, characterized in that the device for serialization includes means for multiplexing multiple frames of digital files representative of a different audio signal at destination different addresses. Wireless system with digital transmission for loudspeakers according to claim 1, characterized in that the transmission circuits have an encryption circuit and the receiving device connected includes a decryption circuit using a secret key stored in the memory of the deserialization circuit. Digital transmission system for loudspeakers according to claim 1 to 4 characterized in that the signal information are serialized according to a protocol comprising a first constituent part (IP) of protocol information, a second part (AD) constituting the address of the recipient, a third party (SNA) constituting the digital signal or the multiplexed digital signals, and a fourth part (IFP) constituting the end of protocol information. Digital transmission system for loudspeakers according to claim 5 characterized in that the protocol includes a fifth part (IC) constituting the speaker control information. Digital transmission system for loudspeakers according to claim 5 characterized in that the protocol includes a sixth part (CE) constituting at least one encryption key. Digital transmission system for loudspeakers according to claim 1 to 7 characterized in that it comprises means for include control commands allowing individual adjustment of each loudspeaker, in the serial signal circulating in packets. Digital transmission system for loudspeakers according to claim 1 to 7 characterized in that it comprises means for conversion of an analog signal into a digital signal, arranged upstream means for compressing the file representative of the audio signal, when the audio signal to be transmitted is of analog type.

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