Abstract:
An audio communication system for use in the passenger compartment of a vehicle providing full duplex communication through a plurality of speakers and microphones while substantially eliminating unwanted external interference and feedback. A digital signal processor further integrates an audio entertainment and mobile transceiver subsystems. The subsystems are operated by the microphone from one or more positions within the vehicle so that each passenger has access to a cellular phone or can control the audio entertainment system.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to a communication system, and more particularly to a full duplex communication system for simultaneously transmitting voice information between front and rear seating areas while integrating voice actuated control of vehicle electronic subsystems. 
     In a typical vehicle, a driver of the vehicle must, of necessity, face forward in the direction of forward travel of the vehicle. In passenger compartments containing additional rows of seats, the driver and any other front seat passengers are thus facing away from rear seat occupants. Consequently, a passenger may have difficulty understanding or hearing the speech of the driver or anyone else forward of the passenger. 
     It is known to use a microphone in the front or rear seating area to pick up voices which are then amplified and reproduced by a speaker in another seating area. A particular problem encountered in such a system is acoustic feedback between the speaker and closely spaced microphones located at each occupant position. Microphone reception of vehicle related noise is retransmitted through the microphones and speakers located within the passenger compartment thereby further degrading communication efficiency. Another problem is that known systems allow only one passenger to speak at a time thus preventing the speech of one passenger if either passenger attempts to speak over the other. 
     A further limitation of known systems is associated with the control of vehicle subsystems. Known systems are primarily controlled solely from the operator position and are limited to manual switch activation. However, it is desirable at times to provide passengers with control of vehicle subsystems such as an audio entertainment or cellular phone subsystems to eliminate tasks demanded of the operator. 
     SUMMARY OF THE INVENTION 
     The present invention provides a full duplex communication system for a vehicle passenger compartment which integrates voice actuated control of vehicle electronic and entertainment systems. 
     In general terms, this invention is an audio communication system for use in the passenger compartment of a vehicle which includes a first microphone and a first speaker located at a first position of the passenger compartment, such as proximate to the operator&#39;s position. A second microphone and a second speaker are located a distance away from the first microphone and speaker at a second position within the passenger compartment. The second microphone and the second speaker can be located, for example, at a passenger position in the rear of the vehicle. 
     Preferably, a microphone and a speaker are located at each occupant position within the vehicle passenger compartment. A plurality of microphone and speaker combinations can be located within the passenger compartment and the digital signal processor simultaneously outputs the signals of each microphone through all the attached speakers. The speakers are, preferably, the same audio system speakers commonly installed in passenger vehicles for use with the audio entertainment system. The digital signal processor transmits the signal generated by the microphones while simultaneously canceling non-input signals originating external to the system. The digital signal processor thus allows full duplex communication while substantially eliminating unwanted external interference and feedback. 
     Modem vehicles typically include an audio entertainment subsystem such as a radio and often include a mobile transceiver, such as a cellular phone. The present invention integrates each subsystem into the vehicle communication system. The subsystems are voice actuated from one or more positions within the vehicle. Thus, each passenger has access to a cellular phone or can control the audio entertainment system. 
     In systems intended for high volume vehicle production, it is desirable to reduce the parts and cost of a communication system. The usage of voice actuated vehicle controls and communication through a common processor, microphones, and speakers reduces the quantity of parts and the overall cost of the communication system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows. 
     FIG. 1 is a top view showing a communication system of the present invention incorporated into a passenger compartment of a vehicle; and 
     FIG. 2 is a block diagram showing the communication system of FIG. 1 in greater detail. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a vehicle communication system  10  of the present invention installed in a vehicle passenger compartment  11  having a front end  12  and a rear end  13 . A front seat  14  provides seating for a driver, and a rear seat  15  provides seating for the rear passengers. In the illustrated embodiment, four microphones  20 - 26  are located adjacent four speakers  30 - 36  in the vehicle passenger compartment  11 . The first input microphone  20  and the second input microphone  22  are located at a first position, here illustrated as the front end  12  of the vehicle. A third  24  and fourth  26  input microphone are located at a second position, here illustrated as the rear end  13  of the vehicle. First  30  and second  32  speakers are located adjacent the first  20  and second  22  input microphones in the first position  12  and third  34  and fourth  36  speakers are located adjacent the third  24  and fourth  26  input microphones in the second position. Input signals from microphones  20 - 26  are provided to a signal processing circuit  40  which interprets the signals and provides output signals to the speakers  30 - 36 . Preferably, the speakers  30 - 36  are the same speakers used by an audio entertainment system and therefore any number of speakers can be integrated to the system while duplication of components is minimized. 
     The microphones  20 - 26  are located adjacent each speaker  30 - 36  and are preferably located to provide ready access to the driver and each passenger. Each microphone  20 - 26  and speaker  30 - 36  are connected to a digital signal processing module  40  which can be located behind a vehicle dashboard  16 , for example. 
     FIG. 2 illustrates, in block diagram form, the communication system of FIG. 1 in greater detail. In one embodiment a first microphone signal is generated by the microphone, when, for example, a driver wishes to speak to the vehicle passengers. The signals output from the microphones  20 - 26  are passed to the digital signal processor  40 . As will be further described below the microphone signal is passed by the digital signal processor  40  to the appropriate speakers  30 - 36  or electrical subsystem. 
     When communication is initiated from the driver for example, microphone signals are generated by the first microphone  20 . The microphone signals are passed directly to the digital signal processor  40 . The digital signal processor  40  analyzes the the microphone signals and directs the speech signals generated from the first microphone to an amplifier  42  which amplifies the signal in a known manner. The amplified speech signals are there passed to every speaker  32 - 36  not adjacent to the first microphone  20 . 
     Signals not originating from the first microphone  20  are stripped away by the digital signal processor  40 . However, the speech signals which are input to the first microphone  20  do produce an output from the digital signal processor  40  and are thus amplified and passed to the non-adjacent speakers  32 - 36 . Therefore, the signals output from the speakers  32 - 36  are stripped away and not contributed to the input of the first microphone  20  and acoustic feedback is substantially prevented. 
     The digital signal processor  40  preferably provides a filter between the speakers  30 - 36  and the microphones  20 - 26 . The digital signal processor  40  can additionally provide noise cancellation in circuitry or signal processing software to eliminate low frequency periodic noise such as that which originates from the vehicle engine or tires. 
     The amplifier  42  preferably provides a fixed gain which is adequate to enhance conversation quality in the vehicle but which is at a level where acoustic feedback does not occur. Alternatively, the total gain of the system (i.e, volume) can be controlled by the passengers up to a maximum gain which corresponds to a gain below the level where acoustic feedback is likely to occur. 
     FIG. 2 further shows a preferred embodiment for integrating the communication system of the present invention with voice actuation of vehicle subsystems. Specifically, the communication system shares the microphones  20 - 26  and speakers  30 - 36  with an integral cellular phone  50  and an audio system  52 . Additionally, any vehicle component  56  operated electrically such as lights, windshield wipers, and climate controls can be further integrated with the digital signal processor  40  to provide voice actuation and control. 
     An audio entertainment subsystem  52 , such as, a radio, a cassette player, and/or CD system, generates an output to each of the speakers  30 - 36 . The digital signal processor  40  is connected with the audio entertainment subsystem  52  to control operation of the audio system  52  in response to operator inputs. Preferably, each microphone  20 - 26  receives voice input from the driver or passenger seated adjacent to one of the microphone  20 - 26 . Each passenger is thus able to control the audio entertainment system  52  from any position within the passenger compartment. 
     As the communication system shares the speakers  30 - 36  with the audio entertainment subsystem  52 , the digital signal processor  40  overlays inter-vehicle communication and the output of the audio entertainment subsystem  52 . Additionally, the audio entertainment system  56  can be automatically muted or reduced in volume when inter-vehicle communication is initiated to further improve the ability of the passengers to communicate. 
     The digital signal processor  40  firther integrates a hands-free mobile transceiver subsystem  54 , such as a cellular phone. The digital signal processor  40  couples the microphones  20 - 26  and speakers  30 - 36  to the transceiver subsystem  54  such that each passenger can speak and hear through the cellular phone in hands-free mode. When the transceiver subsystem  54  is not in hands-free mode the digital signal processor  40  switches the speakers  30 - 36  and microphones  20 - 26  to inter-vehicle communication and normal audio entertainment features. Preferably the speakers  30 - 36  are available for normal audio entertainment, and the microphones  20 - 26  remain on standby prior to initiation of inter-vehicle communication. Further, the digital signal processor  40  recognizes selection of the audio entertainment system  52 , or the transceiver subsystem  54 , and configures the microphones and speakers as appropriate for the desired subsystem. 
     Preferably, the transceiver subsystem  54  and audio entertainment subsystem  52  controls can be selectively dedicated to just one microphone. Thus, only the control position, preferably the driver&#39;s position, would have access to each subsystem. Additionally, the control position can preferably connect one or more other positions to have access to the subsystems. Thus, only the driver, or those passengers selected by the driver, would have full access to the subsystems. 
     The foregoing description is exemplary rather than limiting in nature. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.