Wireless system with digital transmission for loudspeakers

The present invention relates to a wireless transmission system for digital speakers.

It is known wireless speaker systems in which a analog audio signal is converted into frequency-modulated signal, frequency-modulated signal being transmitted over the power lines the alternating current of a home network. The signal received by the network Domestic is then converted into an audio signal after the extraction frequency modulated signal.

Such education is especially disclosed by US 4 829 570. This patent also envisages the use of a device compression to allow the compression of analogue signals issued by a compact disc player, the wide dynamic range requires very high bandwidth to enable transmission in frequency modulation. Broadband and significant deviations many problems that are fixed in this document the use of a compressor circuit to reduce the total dynamic range the audio signal. This document already allows us to realize a first difficulty is the limitation of stereophonic systems in particular using frequency modulation and operating with analog systems such as variable frequency oscillators.

When we want to move from simply stereophonic quality to stereophonic quality of the type "CD Digital", the amount of information transmitted is such that it is very quickly limited by frequency modulation by bandwidth.

Finally, this type of system taught by US Patent 4,829,570 is acceptable for uses for private purposes in the home network a personal residence but can be easily implemented in a building or even less in communities or groups commercial. Indeed, the music played on the power network will be captured at the same time by all the speakers installed and connected to the network. This poses a copyright settlement problem and it is therefore desirable to provide a device that avoids a diffusion widespread.

Finally, such a device requires, for both channels stereo, providing a first carrier frequency for the first channel and a second carrier frequency for the second channel. These frequencies should be selected according to specific conditions, which will also limit the possibilities of bandwidth.

A first object of the invention to provide a wireless system Digital transmission for speakers that allow the dissemination of stereophonic signal quality compact digital disc and / or remote control.

This first object is achieved by the fact that the wireless system Digital transmission for speakers includes:<ul><li>compression means Representative signal file type of Digital Audio "Compact Disc", a transmitting device comprising means for transforming this compressed signal into signal series circulating packet to a quadrature modulator circuit phases and means to transmit the output signals of the circuit phase quadrature modulator to the feed home network electricity ;</li><li>a receiving device comprising connection means on the home network and extract the power supply signal by a phase quadrature demodulator in the information packets carrying the digital audio signal to transform it into a signal Digital parallelized sent to a decompression circuit;</li><li>ways to convert digital signals uncompressed into an analogue signal intended to supply a loudspeaker after adequate amplification.</li></ul>

A second purpose is to allow the transmission of multiple signals music to different speakers.

This object is achieved in that the serialization means comprise means for inserting in the signal packets a serialized destination address ; and in that the receiving means comprise means for compare the address in the received packet to the specific address receiving device to which the speaker is connected.

In another feature, the serialization device comprises means for multiplexing several frames of digital files representative of a different audio to different addresses.

Another object of the invention is to provide a system for to ensure that copyright can not be defrauded.

This third object is achieved in that the transmission circuits comprise an encryption circuit and the connected reception device comprises a decryption circuit using a secret key stored in memory deserialization circuit.

According to another embodiment, the digital signal information is serialized according to a protocol comprising a first part constituting protocol information, a second constituent part the address of the recipient, a third part constituting the signal digital or the multiplexed digital signals, and a fourth portion constitutive information End protocol.

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

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

In another feature, the system comprises means for include control command to the individual adjustment each speaker in the series signal flowing per pack.

In another feature, the system includes conversion of an analog signal means digital signal, arranged upstream of the file compression means representative of the audio signal when the audio signal to be transmitted is analog type.

Other features and advantages of the present invention appear more clearly on reading the following description made reference to the accompanying drawings in which:<ul><li>1 shows a schematic view of the electronic circuit enabling the implementation of the invention;</li><li>2 shows a schematic view of a system type of audiovisual "jukebox" in which the device of the invention can to be used.</li></ul>

The invention will now be described in connection with Figure 1 of wherein the reference (13) denotes the two conductors of a network power domestic electrical energy of a building or premises to house a public or community such as for example a bar, a department store, a sports arena, etc .... On this network power supply is connected a transmitting device (10) comprising the primary winding of a first transformer (108) which delivers by its secondary winding through a diode rectifying circuit a power signal to a circuit (100) which extract power, the signal the rectified AC sector, the signals necessary for supply of the different circuits of the device. In parallel, the primary of the first transformer (108) is connected a second transformer (109) whose secondary winding is fed through a transistor by a circuit (101) of phase quadrature modulation. This circuit (101) is voltage supplied by the circuit (100) and receives from a microcontroller (102) streams of packets of (P1, P2) of data representing information digital serialized according to a protocol (P) shown below. This protocol (P) comprises a first part (IP) constituting information protocol, a second part (AD) constituting the address of the recipient or addresses of each recipient, any third part (IC) constituting the speaker control information, a possible fourth part (EC) constitutes a key Encryption or more keys, each for an address, Part Five (SNA) constituting the digital audio signal or multiplexed audio signals, each signal being associated with one of the addresses recipient, and finally, a sixth part (IFP) constitutive information End protocol.

The signals are quadrature modulated phases by circuit (101) on a carrier, between 200 and 300 kHz are superimposed on the AC signal from sector via the transformer (109). The digital audio signals from the audio source, after compression, represent a data rate of 128 kilobits 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 perform the multiplexing of multiple audio sources for by example, to send a piece of classical music to a first speaker for being sent at the same time a piece of jazz music to a second speaker, each with a specific address and its own decryption key.

In this case, the device (10) address one or more frames to a user identified by a card or a housing (11) connected to the speaker. The transmitting device (10) and the or the receiving devices (11) are not interconnected only through the network of electrical conductors domestic power supply.

Finally, the microcontroller operation program (102) will upon receiving commands sent by a housing remote control (12), emitting for example a wave signal to a sensor (1020) to include the commands thus generated by this housing (12) in the package, so as to constitute the control information of the loud speaker. These control information allows individual adjustment each speaker by adjusting the right channel, the left channel, the bass, treble, volume, etc .....

When one wishes to protect the conveyed audio information on Home network, to allow copyright collection and prevent the same piece of music can be listened to by people did not pay the copyright, add in a device encryption circuit (103) placed between the compression circuit (104) and the microcontroller (102). In the case where the source music signals is not not like "Digital", a converter is assistant device digital analog converter (106) receiving at its input the output signals an analog amplifier (107), which receives the audio signals analog.

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

The memory of the microcontroller (112) of the housing (11) is loaded with the identification address that compares the address to the received address in the packet to identify whether the digital information audio intended for it or are intended for another speaker. Of Similarly, the memory of the microcontroller is loaded at boot or manufacturing with a decryption key. Loading at initialization with the decryption key can be done through the fourth area of ​​the protocol.

The circuits analog-digital converters (ADC / or CNA) compression encryption and amplification of the transmitter device (10) can be achieved, for example, by a digital signal processor sold by MOTOROLA under reference 563XX and commonly called "DSP (Digital Signal Processor)."

Similarly, decryption circuitry, decompression and analog-digital conversion of the receiving device (11) can be made in a digital signal processor sold by MOTOROLA under reference 563XX and commonly called "DSP (Digital Signal Processor) ".

It is thus possible with such a device, enable the implementation of multiple speakers in different rooms provided they are powered by the same phase of the network to which the transmission device (10) will be connected. This transmission device (10) will firstly be connected to a source of audio signals which can be e.g. digital output from a CD player or digital output a hard drive of a jukebox as described in Figure 2 and corresponding to the PCT patent application FR 95 01333 published under the No. WO 96/12 256 and secondly to the power system conductors power supply of the building or premises. The jukebox of Figure 2 is constituted by a central unit (1), a microprocessor which is a system compatible high performance PC. The choice when setting out fell on a system of the "Intel 80486 DX / 2" has storing means and the following characteristics:<ul><li>compatibility with the local Vesa bus,</li><li>processor cache: 256 kB,</li><li>serial and parallel ports of high-performance,</li><li>Graphics adapter SVGA type microprocessor</li><li>Bus Controller SCSI / 2,</li><li>RAM static self-powered.</li></ul>

Any other central unit with equivalent performance or greater can be used in the invention.

This CPU controls and manages a control circuit its (5), a circuit (4) for controlling the telecommunications circuitry (3) control input, a circuit (2) for controlling the storage mass, a circuit (6) for controlling the display means. The display means comprise mainly a video monitor (62) 14-inch flat panel display (35.56 cm) without interlacing type SVGA high resolution and low radiation, it is this monitor which is used for image reproduction (for example, album covers musical selections), graphics or video clips.

Mass storage means (21) using disks hard type "SCSI" high speed and high capacity are associated with storage means already present in the microprocessor device. These means are used to store digitized audiovisual information and compressed.

A telecommunications modem adapter (41) High Speed 28.8 kbps is integrated to allow connection to a distribution network audiovisual information controlled by a central server.

To reproduce the audio data selections musical, the system includes speakers (54) receiving the signal amplifier receiver (53) connected to an electronic circuit (5) type "Music Synthesizer" designed to support a large number of input sources while providing an output having a quality Type "CD" (CD), as for example, the audio adapter multimedia microprocessor, type "map" Sound Blaster "" SBP32AWE from Creative Labs Inc. on which two memory buffers (56, 57) are added in purpose to be explained.

Similarly, the control circuit of the display means also includes two buffers (66, 67) in the explicit purpose later.

A thermally controlled 240 watt ventilated power provides power to the system. This power supply is protected against the surges and harmonics.

The audiovisual reproduction system manages, through its input controller circuit (3), touch screen (33) "Intelli Touch" 14 inches (35.56 cm) from Elo Touch Systems, Inc., includes a panel of glass coated using "advanced surface wave" and a bus controller type "AT". This touch screen allows, after be displayed on the video monitor (62) or a TV Screen (61) various selection information used by customers as well as the selection data used by customers, as well as information controls and management controls 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 it has to a keyboard connector, controlled by a key lock (32) through the interface circuit (3).

The input circuit (3) also interface with the system remote control (31) consisting, for example:<ul><li>an infrared remote control from Mind Path Technologies Inc., an emitter which has 15 control keys for the system microprocessor and 8 control keys for the projection device,</li><li>an infrared receiver with serial adapter from Mind Path technologies Inc.</li></ul>

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

To house the system, it is further provided a frame or frame in steel with external customizable fittings.

Besides these components, a microphone (55) is connected to the wireless the controller (5), which transforms it into a powerful system of announcements and information to the public or possibly a karaoke machine. Similarly, a speaker system Wireless can be used by the system.

The assembly (31) remote control allows the manager, by example from behind the bar, access and control various commands as :<ul><li>the on-off control of the microphone,</li><li>control muting the speakers,</li><li>control volume control,</li><li>ordering cancel the musical selection being heard.</li></ul>

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

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

This information is transmitted via the unit central (1) to the card (105) on which the elements were added corresponding to the circuit (10), the encryption circuit (103) being directly connected to the buffer circuits (56, 57) in the case where information is already compressed, or by a first connector (1021), avoiding the circuit encryption (103), if the information is already encrypted or not need be, either by a second connector (1031), using the circuit encryption (103), whether the information should be encrypted. In the case where information is not compressed, the buffer will be connected (56, 57) at a third connector (1041) so as to use the circuit of compression.

Thus, by connecting the output of the transformer (108) on the sector, it is possible by connecting the reception circuits (11) in different locations on the sector, supply various loudspeakers remotely, in addition speakers normally provided in the jukebox system (54). This allow a sound system of good quality in all different local ensuring the manager can adjust the volume as local or as loudspeakers provisions.

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