Abstract:
A technique is provided for reducing power consumption of an internally powered console in an audio system through frequency based signal routing. A system employing the technique includes a base unit having an interface for receiving a signal representative of acoustic information. The base unit includes a filter system for splitting the signal into low-frequency and high-frequency component signals. The low-frequency signal is routed to a first audio driver for reproduction. The high-frequency signal is routed to a device that includes a second audio driver. By removing the need to reproduce the low-frequency portion of the acoustic information, the power consumption of the device is reduced.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to audio reproduction, and more particularly to reduction of power consumption in audio conferencing system components through frequency filtered signal routing. 
     2. Description of the Prior Art 
     Audio conferencing systems have become an increasingly popular and valuable business communications tool. Conferencing systems are often connected to a network, such as the public-switched telephone network, and are thus being utilized to facilitate natural communication between persons or groups of persons located remotely from each other. 
     Enterprise conference or meeting rooms are typically configured with conferencing systems, often with an audio console being the centerpiece of the conference table. Configuring a conference room as such maximizes the pick-up range of the integrated microphones to efficiently capture as much of the local speech as possible, and maximizes the audible range of the audio reproduced by the integrated speakers. Configuring a conference room with a conferencing system which has one or more audio consoles located on one or more conference tables has an inherent disadvantage when utilizing a “wired” system because connecting cables must be routed from a power source to the table-top console and possibly among various table-top consoles or other system components. Therefore, there is a need for a wireless conferencing system. 
     A wireless conferencing system may be configured with either all components being battery or otherwise internally powered, or possibly with some components being internally powered and a main unit being externally powered. Development of a wireless conferencing system must overcome the ever-present trade-off between power supply/availability and system component/battery size. 
     In addition, components of a wired conferencing system employed in a large conference room may be “daisy-chained” or connected in series. Power availability in such a system configuration needs addressing since the power supply and the cables connecting the system components must provide enough power to supply the entire series arrangement. 
     In addressing the power issues in both wireless and wired conferencing systems, one possible solution is to offer more power to system components. This is not an optimal solution, especially in a wireless system including battery-powered components. An alternative solution, which is additionally needed in the art, is a system and method for reducing power consumption in an audio conferencing system. 
     SUMMARY 
     Systems and methods are provided for reducing power requirements of an internally powered console in a wireless networked conferencing system. The system includes a base unit having a network interface for receiving an signal representative of speech or other acoustic information from a remote conference endpoint. The base unit includes a filter system for splitting the signal into low-frequency component and high-frequency component signals. The low-frequency component signal is routed over an electrical connection to a first audio driver for reproduction of the low-frequency portion of the acoustic information. The high-frequency component signal is routed to a transmitter, which encodes the signal for transmission over a wireless channel to the internally powered console. The console includes a receiver for receiving and decoding the high-frequency component signal and a second audio driver, coupled to the receiver, for reproducing the high-frequency portion of the acoustic information. By removing the need to reproduce the low-frequency portion of the acoustic information, the console&#39;s power consumption is reduced and battery life is correspondingly lengthened. The base unit may additionally include a delay module for delaying the low-frequency component signal relative to the high-frequency component signal in order to localize the conference participants&#39; attention to the console. 
     The power requirement reduction technique described is equally applicable to externally powered audio reproduction components that may benefit from reduced power requirements, and audio systems other than conferencing systems, in which audio drivers are internally powered. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the accompanying drawings: 
         FIG. 1  depicts an exemplary operating environment of a system and method for reducing power consumption in components of an audio conferencing system through selective signal routing, in accordance with an embodiment of the invention; 
         FIG. 2  depicts an exemplary architecture of a base unit of a wireless audio conferencing system such as that depicted in  FIG. 1 , in accordance with an embodiment of the invention; 
         FIG. 3  depicts exemplary frequency response curves of an audio conferencing system provided by the systems and methods described herein, in accordance with an embodiment of the invention; 
         FIG. 4  depicts an exemplary architecture of a console of a wireless audio conferencing system such as that depicted in  FIG. 1 , in accordance with an embodiment of the invention; and 
         FIG. 5  depicts a second exemplary operating environment of a system and method for reducing power consumption in components of an audio conferencing system-through selective signal routing, according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  depicts an exemplary operating environment of a system and method for reducing power consumption in components of an audio conferencing system through selective signal routing, according to an embodiment of the invention. The depiction is essentially a top view of an exemplary audio conferencing system (ACS)  100  located in a conference room  101 . A wireless ACS  100  is utilized in the embodiment shown and described in reference to this figure. 
     The ACS  100  includes a console  102  (depicted on a table  103 ) which is powered by an internal battery or other local power source, and a base unit  104 . Sub-system components of console  102  are described in reference to  FIG. 4  and sub-system components of base unit  104  are described in reference to  FIG. 2 . Base unit  104  is provided with a network connection port  106  for connecting to a network. The system and methods described herein are network independent, but exemplary networks include a circuit-switched network such as the public-switched telephone network (PSTN), a packet-switched network such as the Internet, or an Integrated Services Digital Network (ISDN). The network connection port  106  serves as the communication interface between the base unit  104  and the network, thus providing the capability to exchange signals with remote parties via the network. The signals typically represent the speech originating from conference participants at the local endpoint (conference room  101 ) and from remote endpoints (not shown) connected to and communicating through the network. 
     The base unit  104  is preferably provided with a power port  108  for connecting to a power source, such as an electrical wall socket, in conference room  101 . Alternative embodiments of the base unit  104  may utilize external power sources other than a wall socket, or may utilize an internal power source such as a battery. The base unit  104  is further provided with an internal or external audio driver  110 , commonly referred to as a speaker, for producing sound from an signal. A preferred ACS  100  functions in a manner such that the base unit  104  is utilized to produce the lower end of the audio frequency spectrum, whereas the console  102  is utilized to produce the higher end of the spectrum. Finally, the base unit  104  is also provided with a transmitter  112 , the function of which is described in more detail in reference to  FIG. 2 . Thus, due to the amount of energy required to produce the low frequency audio reproduction and to drive the transmitter  112 , the base unit  104  is preferably externally powered. 
       FIG. 2  depicts an exemplary architecture of the base unit  104  of a wireless ACS  100  ( FIG. 1 ), which preferably functions as the hub of the ACS  100 . The base unit  104  is depicted as an externally powered unit as in  FIG. 1 , but an internally powered unit is also contemplated and within the scope of the present invention. The base unit  104  is connected to the network connection  106  through a network interface  202 , such as a conventional network interface circuit, and preferably to an external power source through a power port  108 . 
     An analog signal representing audio that is received through the network interface  202  routes through an analog-to-digital codec (ADC)  204  in order to convert the analog signal into a digital signal. Note that if the network connection  106 , network interface  202 , and network (e.g., a LAN utilizing technology such as Ethernet, or a WAN such as the Internet) are digital signal based, then it is not necessary to convert an analog signal to a digital signal as described above in reference to the ADC  204 . The digital signal is passed to a processing system  206 , such as a digital-signal processor (DSP), for processing in accordance with embodiments of the invention and as described below. The processing system  206  comprises at least a filtering system  208 , a delay means  210 , and an acoustic characterizer  212 . The filtering system  208  comprises a low pass filter  214  and a high pass filter  216 . 
     Upon engagement with the filtering system  208 , the signal is bifurcated into a low frequency band signal and a high frequency band signal through a standard implementation of a high-order cross-over function. The low pass filter  214  is operative to pass the low frequency signal to the delay means  210 . A preferred cross-over frequency of the filtering system  208  is approximately 400 Hertz, but may vary and still fall within the scope of the present invention. The delay means  210  is operative to delay the low band signal to the audio driver  110  of the base unit  104 , in order to provide an “imaging” function to the console  102  ( FIG. 1 ). By delaying the low band signal (which audio information is reproduced by the audio driver  110  of base unit  104 ) in relation to the high band signal (which audio information is reproduced by console  102 ), a listener is likely to “image” (i.e., direct ones attention and vision) upon the console  102  as opposed to the base unit  104 , since audio precedence has a significant localizing influence. Focusing listeners&#39; attention to the table  103  ( FIG. 1 ) area as opposed to the location of the base unit  104  (e.g., a wall or corner of room  101  of  FIG. 1 ) is a preferred scenario in audio conferencing systems and applications. 
     The delay duration is adjustable and is selected based on information generated by the acoustic characterizer  212 , which is operative to characterize the acoustic response of a room or other operating environment based on known active or passive analysis of acoustic signals. The signal delay provided by the delay means  210  is preferably effected in the digital domain, and is preferably on the order of but not limited to 5 milliseconds. The delay means  210  preferably utilizes conventional methods for providing digital signal delay, such as software or firmware code executing digital delay algorithms by an integrated circuit or other form of processor. 
     After being delayed by the delay means  210 , the low band signal is converted into an analog signal by a digital-to-analog codec (DAC)  218  and amplified by a conventional amplifier  220 . The amplified low band signal is transmitted to the audio driver  110  for conversion to and presentation of audible sound. 
     Referring back to the cross-over function of filtering system  208 , the high band signal is provided by operation of the conventional high pass filter  216 . The high band signal is routed to the transmitter  112  for wireless transmission to the console  102  ( FIG. 1 ) for processing and presentation, as described in reference to  FIG. 4 . A number of conventional wireless data transmission methods may be utilized by the transmitter  112  to transmit the high band and/or control signals to the console  102 , such as RF signals, infrared signals, or other signals in a suitable part of the spectrum. In addition, the base unit  104  is configured with a receiver  222  for receiving signals representing audio information captured by and transmitted from the console  102 . 
       FIG. 3  depicts exemplary, but not limiting, frequency response curves of the ACS  100  ( FIG. 1 ) provided by the systems and methods, described herein, in accordance with a preferred embodiment. In this depiction, the left curve represents the frequency response of the base unit  104  audio driver  110 , and the right curve represents the frequency response of the console  102  audio driver  416  (see  FIG. 4 ). In this embodiment, the cross-over frequency of the filtering system  208  is approximately 400 Hertz at −6 decibels. As depicted, the ACS  100  frequency response is shown with a low cut commencing at approximately 70 Hertz, employed to minimize distortion in the sound presented by the audio driver  110  ( FIGS. 1 and 2 ) of the base unit  104  ( FIGS. 1 and 2 ). Additionally, the ACS  100  frequency response is depicted with a high cut to minimize the power used by the console  102  to produce inaudible or noise frequency bands. 
       FIG. 4  depicts an exemplary architecture of the console  102  of a wireless ACS  100  ( FIG. 1 ). Being a wireless unit in the preferred embodiment, the console  102  is depicted with a battery  402 , for providing power to at least a transceiver  404 , a processor  406 , and an amplifier  414 . Alternative internal power sources may be provided in the console  102  and still fall within the scope of the invention. The transceiver  404  is operative to receive the high band audio signals and various control signals from the base unit  104  ( FIGS. 1 and 2 ), as described above in reference to  FIG. 2 . In addition, the transceiver  404  is configured to transmit signals representing local (from within room  101  of  FIG. 1 ) audio from the console  102  to the receiver  222  ( FIG. 2 ) of base unit  104  for transmission to the network through the network interface  202  ( FIG. 2 ). An alternative embodiment may employ triple diversity in the transceiver configuration, wherein three antennas are utilized and signals are sampled from each, and the antenna with the best signal strength is used as the active antenna. 
     The transceiver  404  is coupled to the processor  406  whereby the coupling facilitates transmission of signals therebetween. In embodiments wherein the base unit  104  transmits command signals to the console  102 , or in embodiments wherein signals other than the audio signals are transmitted between the base unit  104  and the console  102 , a multiplexer (MUX) and/or demultiplexer (DEMUX) (not shown) may be coupled to the transceiver  404  and the processor  406 , or may be a sub-component of the processor  406 . 
     The processor  406  is capable of performing a number of functions, including for example, acoustic echo cancellation, management of RF or other transmission signals (which may include timing the data flow on the RF signal in a time-division multiplexing scheme), power management, and the like. Next, the console  102  further comprises at least one analog-to-digital codec (ADC)  408  and a digital-to-analog codec (DAC)  412 . Each ADC  408  is configured for converting analog signals representing audio received from at least one microphone  410 . If a multiple microphone  410  configuration is employed, a summing device (not shown) may be utilized to sum the multiple signals from the microphones  410 . Alternative microphone  410  and ADC  408  configurations are contemplated and still within the scope of the invention, such as summing the microphone signals prior to converting to digital format and thus employing a single ADC  408 , or configuring the processor  406  to perform the functionality of the ADC  408 . 
     The processor  406  is further operative to transmit digital audio data to the DAC  412  for conversion to analog format. Again, the DAC  412  functionality may be included in the processor  406  and remain within the scope of the invention. The analog signal is sent to the conventional amplifier  414  for amplification whereby the amplified high band signal is then transmitted to an audio driver  416 , configured for producing sound from the signal. 
     Having described the configuration and functionality of the console  102  and the base unit  104 , it can be appreciated that by selectively routing signals based on audio frequency, an audio conferencing system such as ACS  100  can perform with reduced power consumption by the battery (or other internal power source) powered console, i.e., console  102 . The reduction in power consumption by the console  102  is effected by routing a defined frequency band away from the internally powered console  102  and to the externally powered base unit  104  audio driver  110 , thus reducing the amount of power necessary for the console  102  audio driver  416  to produce its acoustical output. Reducing power consumption results in a system that is more efficient than prior art audio systems in terms of internal power requirements of the console  102 , and thus also results in a spatially efficient console  102  through reduction in battery  402  size. 
     It is additionally contemplated that the frequency based signal routing techniques described herein can benefit audio systems and environments other than audio conferencing systems. One non-limiting example is the benefit offered a home stereo or theater system that includes wireless speakers. Those skilled in the audio art can recognize other implementations of the power reduction techniques described herein that would benefit from utilization thereof. 
     An alternative embodiment of an ACS  100  ( FIG. 1 ) may utilize two or more consoles  102  per table  103  ( FIG. 1 ), wherein each console  102  represents a separate audio channel for the respective microphones  410  and audio drivers  416 . An additional embodiment is contemplated wherein each console  102  may be configured with a low duty cycle processor  406  for acoustic echo cancellation, etc. In such a configuration, the processor  406  is intermittently powered on and off as opposed to remaining constantly powered, thus contributing to the minimization of power usage by the console  102 . 
       FIG. 5  depicts an exemplary operating environment of a system and method for reducing power consumption in components of an audio conferencing system through selective signal routing, according to another embodiment of the invention. The depiction is essentially a top view of an exemplary audio conferencing system (ACS)  500  located in a conference room  501 . An externally powered, or wired, ACS  500  is utilized in the embodiment shown and described in reference to this figure. 
     The ACS  500  includes at least one console  502  (with two consoles  502  depicted on a table  503 ) and a base unit  504 , both of which are powered by an external power source. Sub-system components of console  502  are similar to the components of console  102  ( FIG. 4 ), with the exception of the battery  402  and transceiver  404  ( FIG. 4 ). Sub-system components of base unit  504  are similar to those of base unit  104  ( FIG. 2 ), with the exception of the transmitter  112  and the receiver  222  ( FIG. 2 ). The consoles  502  are coupled together by a cable  505  to transport, for example, power, command, and audio signals between the consoles  502 . 
     Base unit  504  is provided with a network connection port  506  for connecting to a network. The network connection port  506  serves as the communication interface between the base unit  504  and the network, thus providing the capability to exchange signals with remote parties via the network. In addition, the base unit  504  and one of the consoles  502  are coupled together by a cable  507  to transport, for example, power, command, and audio signals between the base unit  504  and the consoles  502 . 
     The base unit  504  is preferably provided with a power port  508  for connecting to a power source, such as an electrical wall socket, in conference room  501 . Alternative embodiments of the base unit  504  may utilize external power sources other than a wall socket, or may utilize an internal power source such as a battery. The base unit  504  is further provided with an internal or external audio driver  510 , commonly referred to as a speaker. The ACS  500  depicted functions in a manner similar to the ACS  100  ( FIG. 1 ) in that the base unit  504  is utilized to produce the lower end of the audio frequency spectrum, whereas the consoles  502  are utilized to produce the higher end of the spectrum. 
       FIG. 5  is used to depict a wired ACS  500  configuration and to describe the advantages that utilization of the techniques described herein offers a wired audio system. In a wired ACS  500 , the amount of power consumed by console  502  remains an important system design parameter and thus the invention described herein consequently offers advantages when employed in a wired system. A wired audio conferencing configuration that would benefit from implementation of embodiments of this invention is one in which several consoles  502  are connected in series, or daisy-chained. Such a system configuration requires power consumption efficiency because the total current requirement of the consoles  502  is additive. Thus, implementing the techniques described herein would result in smaller, and thus cheaper and more user-friendly, cables  505  and  507 . Another example of benefits provided to a wired ACS  500  is extended low frequency, or bass, response from the base unit  504 . It is noteworthy that with an externally powered console  502 , the cross-over frequency would preferably be different than that exemplified above with respect to the wireless ACS  100 . 
     It will be recognized by those skilled in the art that while the invention has been described above in terms of preferred embodiments, it is not limited thereto. Various features and aspects of the above-described invention may be used individually or jointly. Further, although the invention has been described in the context of its implementation in a particular environment and for particular applications, those skilled in the art will recognize that its usefulness is not limited thereto and that it can be utilized in any number of environments and applications and that its scope is limited only by the claims appended hereto.