Abstract:
Methods and systems for automatic configuration of wireless speakers are disclosed. A system is described whereby a wireless speaker is configured to use an audio tone to generate a sound wave. The sound wave is received by an audio input/output device, which uses the received sound wave to generate audio information. A processor is configured to use the audio information to determine a distance between the wireless speaker and the audio input/output device, and to configure an audio parameter of the wireless speaker as a function of the distance.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. Nonprovisional patent application Ser. No. 11/860,004, entitled “Methods and Systems to Provide Automatic Configuration of Wireless Speakers” and filed on Sep. 24, 2007; which is incorporated by reference herein in its entirety for all purposes. 
     
    
     FIELD 
       [0002]    Embodiments of the invention pertain to methods and systems to provide automatic configuration of wireless speakers. 
       BACKGROUND 
       [0003]    In the consumer electronics and computer industries, transmission of audio signals from a host player to remote device speakers has generally been accomplished over an analog wired interface comprising speaker. With the advent of digital audio content, the desire to maintain the pristine digital audio signal as far as possible along the audio signal chain has motivated designers to pursue digital interfaces to replace unsightly, signal-loss-prone analog speaker wires. 
         [0004]    The High-Definition Multimedia Interface (HDMI) is an all-digital audio/video interface capable of transmitting uncompressed streams. HDMI is compatible with High-bandwidth Digital Content Protection (HDCP) Digital Rights Management technology. HDMI provides an interface between any compatible digital audio/video source, such as a set-top box, a DVD player, a PC, a video game console, or an audio video (AV) receiver and a compatible digital audio and/or video monitor, such as a digital television (DTV). 
         [0005]      FIG. 1  shows an example of a conventional prior art audio video system that includes a source, HDMI AV receiver, with a centralized amplifier connected via an HDMI cable to HDMI DVD player and also connected via an HDMI cable to a display (HDMI TV). The HDMI AV receiver is also connected via analog speaker wires to a set of 6 speakers, each connected point-to-point from the HDMI AV receiver. Speakers in  FIG. 1  are identified as follows: Front Left (FL), Front Right (FR), Center (C), Surround Left (SL), Surround Right (SR), and Low Frequency Effect (LFE), also commonly referred to as a “subwoofer.” 
         [0006]      FIG. 1  contains components which can maintain pristine digital audio and video from source to display through HDMI interconnects. The interconnects from the source to the speakers still comprise analog via conventional speaker wires. For prior art systems containing 6 individual speakers, and other, more advanced systems that support up to 8 speakers or more, the speaker wire interconnections not only suffer from analog signal loss, but the speaker wire interconnections can be an eyesore or be a wire-hiding challenge. 
         [0007]    Additionally, configuration and calibration of the speakers in  FIG. 1  is performed with a wired analog microphone coupled by a wire to the HDMI AV receiver. Test tones are sent from the AV receiver to a test speaker, which reproduces the test tones. The wired microphone coupled to the AV receiver listens for the test tones reproduced by the test speaker. The AV receiver then calculates delay and volume parameters for the test speaker. The wired microphone is limited in its location and convenience of use by the wire coupled to the AV receiver. The wired microphone also provides analog audio input, rather than pristine digital audio. 
       SUMMARY 
       [0008]    For certain embodiments of the present invention, an apparatus is described that includes an AV receiver with a wireless audio module (WAM) host. The apparatus further includes a plurality of wireless speakers each having a WAM device to enable bidirectional communications with the WAM host. The apparatus further includes a wireless input/output device to enable bidirectional communications with the WAM host in order to automatically configure the plurality of wireless speakers to optimize audio parameters of the wireless speakers. The automatic configuration includes determining a location for each speaker in order to identify each speaker. The automatic configuration further includes setting time delay parameters for each speaker. The automatic configuration further includes setting volume parameters for each speaker. 
         [0009]    For some embodiments of the present invention, a method for automatic configuration of a plurality of wireless speakers is described. The method includes sending an audio test tone from a wireless audio module (WAM) host located in an audio receiver to the plurality of wireless speakers. The method further includes sending the audio test tone from each wireless speaker to a wireless input/output device located in an optimum location for configuring audio parameters associated with the plurality of wireless speakers. The method further includes sending audio information from the wireless input/output device to the receiver in order to enable an automatic configuration of the plurality of wireless speakers. 
         [0010]    Other features and advantages of embodiments of the present invention will be apparent from the accompanying drawings and from the detailed description that follows below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Embodiments of the present invention are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which: 
           [0012]      FIG. 1  is a block diagram of an example of a prior art AV system having a HDMI AV receiver coupled to analog speaker wires and an analog microphone. 
           [0013]      FIG. 2  is a block diagram of an apparatus having an AV receiver with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. 
           [0014]      FIG. 3  is a block diagram of an AV system having a DVD player with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. 
           [0015]      FIG. 4  is a block diagram of an AV system having a display with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. 
           [0016]      FIG. 5  is a block diagram of an AV system having a integrated DVD player and display with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. 
           [0017]      FIG. 6  is a flowchart of a method for configuring wireless speakers with a wireless input/output device in accordance with an embodiment of the present invention. 
           [0018]      FIG. 7  is a block diagram of an AV system having a source with a WAM host in communication with wireless speakers having embedded input/output devices in accordance with an embodiment of the invention. 
           [0019]      FIG. 8  is a flowchart of a method for configuring wireless speakers having embedded input/output devices in accordance with an embodiment of the present invention. 
           [0020]      FIG. 9A  is a block diagram of a wireless speaker with a WAM Device in accordance with an embodiment of the invention. 
           [0021]      FIG. 9B  is a block diagram of a system with a WAM Host communicating with a WAM Device in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    A method for automatic configuration of a plurality of wireless speakers is described. The method includes sending an audio test tone from a WAM host located in a source (e.g., an AV receiver, a DVD player, a display, a integrated DVD player/display, a HDMI AV receiver, a HDMI DVD player, a HDMI display, or an HDMI integrated DVD player/display) to the plurality of wireless speakers. The method further includes sending the audio test tone from each wireless speaker to a wireless input/output device located in an optimum location for configuring audio parameters associated with the plurality of wireless speakers. The method further includes sending audio information from the wireless input/output device to the source in order to enable an automatic configuration of the plurality of wireless speakers. 
         [0023]    An intended advantage of providing automatic configuration of wireless speakers is that the wireless input/output device is not coupled to the source. A consumer can easily configure the wireless speakers by locating the wireless input/output device in an ideal listening and configuration position. Another intended advantage is that bidirectional communications between the source and wireless input/output device can optimize the configuration and calibration procedures. Another intended advantage is that the wireless input/output device can be embedded in a remote source controller or in the wireless speakers. 
         [0024]      FIG. 2  is a block diagram of an apparatus having an AV receiver with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. The apparatus  200  includes the AV receiver  202  with a WAM host  204 . The AV receiver  202  is coupled to a TV  220  and a DVD player  290 . For certain embodiments, the AV receiver  202  is a HDMI AV receiver which is coupled to a HDMI TV and a HDMI DVD player. For one embodiment, the apparatus  200  further includes a plurality of wireless speakers  230 ,  240 ,  250 ,  260 ,  270 , and  280  each having a respective WAM device  232 ,  242 ,  252 ,  262 ,  272 , and  282  to enable communication with the WAM host  204 . For another embodiment, the WAM devices and WAM host communicate control and data information bidirectionally. 
         [0025]    The apparatus  200  further includes a wireless input/output device  210  to enable bidirectional communications with the WAM host  204  in order to automatically configure the plurality of wireless speakers  230 ,  240 ,  250 ,  260 ,  270 , and  280  and to optimize audio parameters of the wireless speakers  230 ,  240 ,  250 ,  260 ,  270 , and  280 . 
         [0026]    The automatic configuration of the wireless speakers includes determining a location for each speaker in order to identify each speaker. The automatic configuration further includes setting time delay parameters for each speaker. The automatic configuration further includes setting volume parameters for each speaker. 
         [0027]    For one embodiment, the wireless input/output device  210  is a wireless microphone. For another embodiment, the wireless input/output device  210  is embedded in a remote control device that operates the HDMI receiver. The HDMI receiver can be a separate component or located in a HDMI TV, a HDMI DVD player, or an integrated HDMI TV/DVD player. 
         [0028]    The wireless speakers  230 ,  240 ,  250 ,  260 ,  270 , and  280  may represent a front left speaker  240 , a front right speaker  260 , a center speaker  250 , a surround left speaker  270 , a surround right speaker  280 , and a subwoofer speaker  230 . Additional types and kinds of wireless speakers may be added to the apparatus  200  in accordance with certain embodiments. 
         [0029]    For some embodiments, the apparatus  200  will adjust various audio parameters to optimize playback based on room acoustics for a given location of the apparatus  200 . Communication between the wireless input/output device  210  and the HDMI AV receiver is handled wirelessly to simplify the operation for the end user or consumer. The wireless input/output device  210  can be easily located in an ideal listening position for configuration of the wireless speakers. A consumer can easily configure audio equipment to optimize audio quality in order to match room acoustics. 
         [0030]    The wireless audio topology of  FIG. 2  reduces clutter and also enables consolidation of devices and multiple locations of the WAM host, as shown in  FIGS. 2-5 . In each of  FIGS. 3-5 , the AV receiver separate component has been combined with an HDMI DVD player  302  ( FIG. 3 ) or an HDMI TV  402  ( FIG. 4 ) or an integrated HDMI DVD player/TV  502  ( FIG. 5 ). This consolidation is possible with the wireless audio topology because a major portion of the AV receiver—namely, the centralized amplifier for the speakers—has been effectively distributed to each of the speakers. With this often large and heat-producing section removed from the core components, replaced with a single WAM host, it is possible to economically create multi-channel audio output capabilities from a source. Such a WAM host can reside inside a DVD player or TV chassis. Even better, neither the DVD player nor the TV need to add any extra connectors to provide such support, as the capability is made available via a wireless system, when the associated antennas are located internal to the box that contains the WAM host. 
         [0031]    Note that the topology between WAM host and WAM devices is point-to-multi-point, implemented via a Ultra Wideband (UWB) Host/Device architecture. Also noteworthy is the ability for bidirectional communications over the wireless link, as depicted with the wireless beacon-like icons. The majority of the data transferred in such an audio application is from host to devices, but very important, infrequent data is sent from the devices to the host, communicating acknowledgements of data transfers and application-specific information, such as packet reception reliability statistics. Such bidirectional communication is also useful to enable detection of devices, which allows for many ease-of-use capabilities, such as auto-configuration of the audio system optimized to the speakers available for output. Additionally, the absence of speaker wires enables a simpler-to-setup, less cluttered environment, and allows the pristine digital audio content to reach the speakers with no signal loss. 
         [0032]      FIG. 3  is a block diagram of an AV system having a DVD player with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. The system  300  includes the HDMI DVD player  302  with the WAM host  304 . The HDMI DVD player  302  is coupled to a HDMI TV  320 . For one embodiment, the system  300  further includes a plurality of wireless speakers  330 ,  340 ,  350 ,  360 ,  370 , and  380  each having a respective WAM device  332 ,  342 ,  352 ,  362 ,  372 , and  382  to enable communication with the WAM host  304 . The WAM devices and WAM host communicate control and data information bidirectionally for various purposes including configuring and calibrating audio parameters of the wireless speakers. 
         [0033]    The system  300  further includes a wireless input/output device  310  to enable bidirectional communications with the WAM host  304  in order to automatically configure the plurality of wireless speakers  330 ,  340 ,  350 ,  360 ,  370 , and  380  and to optimize audio parameters of the wireless speakers  330 ,  340 ,  350 ,  360 ,  370 , and  380 . 
         [0034]    For an embodiment, the DVD player  302  is a home theatre in a box (HTiB) with a wireless audio module (WAM) host  304 . The plurality of wireless speakers each having a wireless transceiver (e.g., WAM device  332 ,  342 ,  352 ,  362 ,  372 , or  382 ) to enable bidirectional communications with the WAM host  304 . 
         [0035]    The automatic configuration of the wireless speakers includes determining a location for each speaker in order to identify each speaker. The automatic configuration further includes setting time delay parameters for each speaker. For example, a speaker closer in distance to the WAM host  304  may require a different delay compared to a speaker further from the WAM host  304  in order to optimize audio parameters from the speakers as a group. The automatic configuration further includes setting volume parameters for each speaker. 
         [0036]    For some embodiments, the system  300  will adjust various audio parameters to optimize playback based on room acoustics for a given location of the system  300 . Communication between the wireless input/output device  310  and the DVD player  302  is handled wirelessly to simplify the operation for the end user or consumer. The wireless input/output device  310  can be easily located in an ideal listening position for configuration of the wireless speakers. A consumer can easily configure audio equipment to optimize audio quality in order to match room acoustics. 
         [0037]      FIG. 4  is a block diagram of an AV system having a display with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. The system  400  includes the display or HDMI display  402  with the WAM host  404 . The HDMI display  402  is coupled to a HDMI DVD player  490 . For one embodiment, the system  400  further includes a plurality of wireless speakers  430 ,  440 ,  450 ,  460 ,  470 , and  480  each having a respective WAM device  432 ,  442 ,  452 ,  462 ,  472 , and  482  to enable communication with the WAM host  404 . The WAM devices and WAM host communicate control and data information bidirectionally for various purposes including configuring and calibrating audio parameters of the wireless speakers. 
         [0038]    The system  400  further includes a wireless input/output device  410  to enable bidirectional communications with the WAM host  404  in order to automatically configure the plurality of wireless speakers  430 ,  440 ,  450 ,  460 ,  470 , and  480  and to optimize audio parameters of the wireless speakers  430 ,  440 ,  450 ,  460 ,  470 , and  480 . 
         [0039]    For some embodiments, the system  400  will adjust various audio parameters to optimize playback based on room acoustics for a given location of the system  400 . Communication between the wireless input/output device  410  and the display  402  is handled wirelessly to simplify the operation for the end user or consumer. The wireless input/output device  410  can be easily located in an ideal listening position for configuration of the wireless speakers. A consumer can easily configure audio equipment to optimize audio quality in order to match room acoustics. 
         [0040]      FIG. 5  is a block diagram of an AV system having an integrated DVD player and display with a WAM host in communication with wireless speakers and a wireless input/output device in accordance with an embodiment of the invention. The system  500  includes the integrated DVD player and display or a HDMI integrated DVD player and display  502  with the WAM host  504 . For one embodiment, the system  500  further includes a plurality of wireless speakers  530 ,  540 ,  550 ,  560 ,  570 , and  580  each having a respective WAM device  532 ,  542 ,  552 ,  562 ,  572 , and  582  to enable communication with the WAM host  504 . The WAM devices and WAM host communicate control and data information bidirectionally for various purposes including configuring and calibrating audio parameters of the wireless speakers. 
         [0041]    The system  500  further includes a wireless input/output device  510  to enable bidirectional communications with the WAM host  504  in order to automatically configure the plurality of wireless speakers  530 ,  540 ,  550 ,  560 ,  570 , and  580  and to optimize audio parameters of the wireless speakers  530 ,  540 ,  550 ,  560 ,  570 , and  580 . 
         [0042]    For some embodiments, the system  500  will adjust various audio parameters to optimize audio performance based on room acoustics. Communication between the wireless input/output device  510  and the integrated DVD player and display  502  is handled wirelessly to simplify the operation for the end user or consumer. The wireless input/output device  510  can be easily located in any desired position for configuration of the wireless speakers. A consumer can easily configure the system  500  to optimize audio quality in order to match room acoustics. 
         [0043]      FIG. 6  is a flowchart of a method for configuring wireless speakers with a wireless input/output device in accordance with an embodiment of the present invention. The method  600  includes sending an audio test tone from a WAM host located in a source (e.g., an AV receiver, a DVD player, a display, an integrated DVD player/display, a HDMI AV receiver, a HDMI DVD player, a HDMI display, or a HDMI integrated DVD player/display) to the plurality of wireless speakers at block  602 . The method  600  further includes sending the audio test tone from each wireless speaker to a wireless input/output device located in an optimum location for configuring audio parameters associated with the plurality of wireless speakers at block  604 . The method  600  further includes sending audio information from the wireless input/output device to the source in order to enable an automatic configuration of the plurality of wireless speakers at block  606 . 
         [0044]    The method  600  further includes determining a location for each wireless speaker in order to identify each wireless speaker at block  608 . The method  600  further includes setting time delay parameters for each wireless speaker at block  610 . The method  600  further includes setting volume parameters for each wireless speaker at block  612 . 
         [0045]    The wireless input/output device can be a separate wireless microphone or embedded in a remote controller of the source. For example, in addition to enabling auto-configuration of the wireless speakers, the wireless input/output device can also be used as a microphone for karaoke or other types of entertainment. 
         [0046]    The wireless input/output device is not coupled to the source in contrast to a prior approach for configuring speakers, wired or wireless. A consumer can easily configure the wireless speakers by locating the wireless input/output device in an ideal listening and configuration position. Also, in contrast to the prior art having one-directional communication, bidirectional communications between the source and wireless input/output device can optimize the configuration and calibration procedures. 
         [0047]      FIG. 7  is a block diagram of an AV system having a source with a WAM host in communication with wireless speakers having embedded input/output devices in accordance with an embodiment of the invention. The system  700  includes the source  702  (e.g., an AV receiver, a DVD player, a display, an integrated DVD player/display, a HDMI AV receiver, a HDMI DVD player, a HDMI display, or a HDMI integrated DVD player/display) with the WAM host  704 . The source  702  may optionally be coupled to a HDMI TV  720  and HDMI DVD player  790  as illustrated in  FIG. 7 . Alternatively, one or more of these components may be included in the source  702 . For one embodiment, the system  700  further includes a plurality of wireless speakers  730 ,  740 ,  750 ,  760 ,  770 , and  780  each having a respective WAM device  732 ,  742 ,  752 ,  762 ,  772 , and  782  to enable communication with the WAM host  704 . The WAM devices and WAM host communicate control and data information bidirectionally for various purposes including configuring and calibrating audio parameters of the wireless speakers. 
         [0048]    Each speaker further includes an embedded wireless input/output device (e.g.,  734 ,  744 ,  754 ,  764 ,  774 , and  784 ) to enable bidirectional communications with the WAM host  704  in order to adjust audio parameters of the plurality of wireless speakers  730 ,  740 ,  750 ,  760 ,  770 , and  780  and to optimize these audio parameters of the wireless speakers  730 ,  740 ,  750 ,  760 ,  770 , and  780 . The embedded wireless input/output device may be an additional separate component as illustrated in  FIG. 7  or it may be an existing component of a speaker such as a speaker cone used to perform the functionality of the input/output device (e.g., a microphone). For example, a speaker can be configured to perform the functionality of a microphone. 
         [0049]    The automatic configuration of the wireless speakers includes determining a location for each speaker in order to identify each speaker. For example, an algorithm with a certain number of reference points may be used to determine a location for each speaker. The automatic configuration further includes setting time delay parameters for each speaker. The automatic configuration further includes setting volume parameters for each speaker. For example, a speaker closer in distance to the WAM host  704  may require a different volume parameter compared to a speaker further from the WAM host  704  in order to optimize audio parameters from the speakers as a group. 
         [0050]    The wireless input/output devices  734 ,  744 ,  754 ,  764 ,  774 , and  784  located in the respective wireless speakers  730 ,  740 ,  750 ,  760 ,  770 , and  780  are not physically coupled to the source in contrast to a prior wired approach for configuring speakers, wired or wireless. The system  700  performs an auto-configuration of the wireless speakers without a wired microphone or remote controller, and without a dependence upon location of the microphone. Also, in contrast to the prior art having a one directional communication, bidirectional communications between the source and wireless input/output devices can optimize the configuration and calibration procedures. 
         [0051]      FIG. 8  is a flowchart of a method for configuring wireless speakers having embedded input/output devices in accordance with an embodiment of the present invention. The method  800  includes sending an audio test tone from a WAM host located in a source (e.g., an AV receiver, a DVD player, a display, or an integrated DVD player/display, a HDMI AV receiver, a HDMI DVD player, a HDMI display, or a HDMI integrated DVD player/display) to the plurality of wireless speakers at block  802 . The method  800  further includes sending the audio test tone from a wireless test speaker to the other wireless speakers not currently being tested at block  804 . The method  800  further includes sending audio information from each wireless speaker not being tested to the source in order to enable an automatic configuration of the tested speaker at block  806 . The operations of blocks  802 ,  804 , and  806  may be repeated in order to test each wireless speaker individually. The method  800  further includes determining a location for each wireless speaker in order to identify each wireless speaker at block  808 . The method  800  further includes setting time delay parameters for each wireless speaker at block  810 . The time delay parameters may include a time reference or base and time stamps to indicate when a speaker received a test tone. The method  800  further includes setting volume parameters for each wireless speaker at block  812 . 
         [0052]      FIG. 9A  is a block diagram of a wireless speaker subsystem with a WAM device communicating with a WAM host in accordance with an embodiment of the invention. To expand upon the automatic configuration of wireless speakers, it is helpful to understand the internals of the wireless speaker subsystem  900 , an example of which is shown in  FIG. 9A . The wireless speaker subsystem  900  includes the WAM device  920 , which receives wireless audio data, auxiliary packets, and/or audio test tones from the WAM host  910  as well as sends back audio information to the host  910 , as required, and further illustrated in  FIG. 9B . The WAM device  920  may also send audio information to other wireless speakers and/or a wireless input/output device as discussed above. 
         [0053]    The wireless speaker subsystem  900  further includes an audio Digital-to-Analog Converter (DAC)  930 , which takes in the digital audio data from the WAM device  920 , and converts it to analog. This analog line-level signal is then sent to the audio amplifier  940 , which can be specifically designed to match the loudspeaker driver  944 , as it is resident in the same enclosure as the driver  944  in this topology. Power  946  is specifically noted in this block diagram showing that there is a need for power in the wireless speakers to allow the active electronics to be powered, as well as allocating sufficient power for the audio amplifier performance desired for the subsystem  900 . 
         [0054]      FIG. 9B  is a block diagram of a system with a WAM host communicating with a WAM device in accordance with an embodiment of the invention. The WAM host  960  includes an audio-in first-in first-out buffer (“FIFO”)  962 , a microprocessor  964 , memory  966  allocated for packet storage, and a certified wireless USB (“CWUSB”) host device  968 . The WAM device  970  includes an audio-out FIFO  978 , a microprocessor  976 , memory  974  allocated for packet storage, and a UWB device  972 . The system  950  receives digital audio input  980  from a source, sends it wirelessly over UWB, and produces digital audio output  990  from each device  970 . The microprocessor included in each WAM embodiment must perform sophisticated management and execute complex algorithms tailored to the wireless medium and the dynamic system requirements. Although not shown in  FIG. 9B , the WAM host must process and transmit all digital audio channels, while a WAM device might only consume a single audio channel. The WAM host&#39;s management of communications, data routing, and synchronization for all the audio channels supported in a system is a significant task. 
         [0055]      FIGS. 2-5  and  7  illustrate various AV systems with 5.1 surround sound based on having a plurality of wireless speakers including a front left speaker, a front right speaker, a center speaker, a surround left speaker, a surround right speaker, and a first low frequency effect (LFE) speaker. For one embodiment, the various AV systems may further include a side left surround speaker and a side right surround speaker to provide 7.1 surround sound. For another embodiment, the various AV systems may further include a second LFE speaker. The various AV systems can provide up to 127 separate wireless audio channels enabling various surround sound arrangements such as 10.2 theatre surround, 22.2 surround, or 22.3 surround. 
         [0056]    High quality pristine digital audio based on optimized wireless speaker configuration can be provided for various arrangements with no wired microphone required. For example, a consumer can quickly and easily configure the wireless speakers without having to properly position a wired microphone. For one embodiment, a speaker configuration can be performed without having a separate microphone component. 
         [0057]    In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.