System for wireless audio signal distribution between a plurality of active loudspeakers

• US 20070160225A1
• Filed: 12/28/2006
• Published: 07/12/2007
• Est. Priority Date: 12/29/2005
• Status: Active Grant

• Current Assignee: Henri Seydoux
• Original Assignee: Henri Seydoux
• Inventors: Seydoux, Henri
• Granted Patent: US 8,054,987 B2
• Time in Patent Office: Days
• US Class Current: 381/79
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04W 40/246 Connectivity information discovery
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

Each loudspeaker (10, 10′) comprises means, e.g. of the Bluetooth type, for establishing a wireless interface with every other loudspeaker of the system. The network configures itself automatically by each loudspeaker searching for the other loudspeakers with which a wireless link can be established directly, by drawing up a table of mutual visibilities, and, on the basis of said table, defining a hierarchical network topology. One of the loudspeakers is designated as the network head so as to be capable of searching for and setting up a wireless link with a remote peripheral capable of transmitting a coded audio signal (A2DP) and/or a control signal (AVRCP). The other loudspeakers receive audio signals sent to them encapsulated in messages that include routing data, either directly, or after said signals have been relayed via another loudspeaker.

Claims

1. A system for distributing audio signals between a plurality of active loudspeakers for playing back said signals by the respective loudspeakers,

the system comprising at least two active loudspeakers (L, R, C, W, L1, L2, R1, R2, L′

, R′

;

10, 10′

), each having;

acoustic transducer means (34, 36);

associated amplifier means (72, 74);

wireless interface means (50, 56, 60) comprising transmitter and receiver means suitable for searching for and establishing a wireless link with any other loudspeaker of the system;

means for applying an audio channel signal to the amplifier means for playback by the transducer means, the audio channel signal being derived from the signal received by the wireless interface means; and

means for configuring the loudspeakers in a network;

the system being characterized in that;

the loudspeakers are initially configured between one another relative to the network in a non-hierarchical manner; and

the configuration means for configuring the loudspeakers into a network are means that operate automatically and that are suitable for;

a) enabling each loudspeaker to search for the other loudspeakers with which it can establish a direct wireless link;

b) on the basis of the results of said search, drawing up a mutual visibility table for each loudspeaker with the others;

c) designating one of the loudspeakers as a network head loudspeaker; and

d) on the basis of the mutual visibility table, defining a network topology that is hierarchical from the head loudspeaker as designated in this way.

2. The system of claim 1, in which the automatic configuration means are also suitable for:

e) making at least one loudspeaker suitable for searching for and establishing a wireless link with a remote peripheral (S;

16, 18, 20, 22) that is capable of transmitting an encoded multichannel audio signal (A2DP) and/or a control signal (AVRCP), the other loudspeakers being designated as dependent loudspeakers.

3. The system of claim 2, in which said loudspeaker suitable for searching for and establishing a wireless link with a remote peripheral is the network head loudspeaker.

4. The system of claim 2, in which the automatic configuration means are also suitable for:

f) making the dependent loudspeakers unsuitable for searching for and establishing a wireless link with a remote peripheral capable of transmitting a coded multichannel audio signal and/or a control signal.

5. The system of claim 2, in which the automatic configuration means are also suitable for:

g) on the basis of the hierarchical network topology, defining for the network a directed graph for broadcasting audio signals to be reproduced by the system of loudspeakers, said broadcasting being performed from the head loudspeaker towards the other loudspeakers of the network either directly from said head loudspeaker, or indirectly with signals being relayed by one or more other loudspeakers of the network.

6. The system of claim 5, in which the system can occupy as alternatives two functional states, namely:

an in-use state in the presence of audio signals broadcast within the network; and

a ready state in the absence of audio signals broadcast within the network;

and in which the automatic configuration means are inhibited while the system is in the in-use state.

7. The system of claim 5, in which the automatic configuration means are also suitable for:

h) receiving from a dependent loudspeaker an order to swap roles and for transmitting said order to the head loudspeaker; and

i) for temporarily attributing dependent loudspeaker status to the head loudspeaker, temporarily attributing head loudspeaker status to the dependent loudspeaker that issued the role swapping order, and adapting the directed broadcast graph accordingly.

8. The system of claim 5, in which said audio signals broadcast over the network are audio signals encapsulated in digital data messages further including message routing data determined from said broadcast graph defined by the configuration means.

9. The system of claim 8, in which the loudspeakers are individualized by respective addresses, said message routing data comprising the address of the loudspeaker transmitting the message, the address of the destination loudspeaker for the message, and a flag specifying whether the destination loudspeaker is to reproduce the audio signals or is to relay them to one or more other loudspeakers of the network.

10. The system of claim 5, in which said audio signals broadcast over the network are multichannel audio signals, and in which the loudspeakers include means (108, 110) for extracting from the multichannel audio signal they receive, the audio channel signal for which they are the destination, for applying said signal of the audio channel to the amplifier means, and optionally for relaying the other audio channel signals to at least one other loudspeaker of the system.

11. The system of claim 1, in which the automatic configuration means are means activated on request by pressing on a button (48) of a loudspeaker, and/or are means activated on each occasion the power supply circuits of a loudspeaker are switched on.

12. The system of claim 1, in which the automatic configuration means are also suitable, in the event of configuration failing, for activating the system in a degraded mode in which a plurality of different audio channel signals are initially combined with one another and are then broadcast to a reduced number of network loudspeakers for playing back by the transducer means thereof.

13. The system of claim 1, further comprising:

means for evaluating the relative transfer times of the audio channel signals to the various respective loudspeakers of the system; and

time shift means for applying to at least some of the audio channel signals respective delays suitable for compensating the differences between the evaluated relative transfer times.

14. The system of claim 1, in which at least one of the loudspeakers of the network further includes wire connection means (52, 76) for connection to a source (24) of audio signals, and analog-to-digital converter means (68) for converting them into a corresponding digital audio signal.

15. The system of claim 1, further including system control means suitable for receiving a control signal from a peripheral and for responding thereto by performing corresponding actions modifying operating parameters of the system, including:

selecting one audio signal source from a plurality of sources that are simultaneously active;

varying the overall volume or the relative volume of the signals played back by the transducer means of the various loudspeakers of the system; and

/or temporarily muting the sound.

16. The system of claim 1, in which the means suitable for designating one of the loudspeakers as the network head loudspeaker operates as a function of predetermined criteria comprising one or more of the following criteria:

MAC address number;

possibility of setting up a direct link between the head loudspeaker and each of the other loudspeakers of the network;

searching for the simplest network topology;

the acoustic role of the loudspeaker in the network.

17. The system of claim 1, in which the means suitable for designating one of the loudspeakers as the network head loudspeaker are means suitable for dynamically redesignating the head loudspeaker in the event of a change in said mutual visibilities of the loudspeakers and/or of said predetermined criteria.

18. The system of claim 1, in which the means in each loudspeaker suitable for searching for the other loudspeakers with which a wireless link can be established directly comprise means for mutual authentication between the loudspeakers.

19. The system of claim 18, in which the mutual authentication means of the loudspeakers are means of the public key algorithm type in which the public key and the private key are predetermined and common to all of the loudspeakers of the system.