Abstract:
A multi-channel wireless audio system includes a sound card for a computer. The sound card includes a signal broadcasting circuit having a first transceiver for wirelessly transmitting digital audio signals to external speakers, a sound chip electrically connected to the signal broadcasting circuit for processing audio signals sent to the signal broadcasting circuit, and an interface connection for connecting the sound card to the computer. The multi-channel wireless audio system also includes a plurality of wireless speaker modules, each including a second transceiver for receiving the wireless digital audio signals from the signal broadcasting circuit, a digital to analog converter for converting the digital audio signals into analog audio signals, an amplifier for amplifying the analog audio signals, and a speaker for converting the amplified analog audio signals into sound.

Description:
BACKGROUND OF INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a professional audio system, and more specifically, to a professional audio system that uses a sound card to wirelessly transmit multi-channel signals to speakers.  
           [0003]    2. Description of the Prior Art  
           [0004]    In professional audio systems, a large number of audio channels can be used to output sounds for various input devices. For example, compact disc players output sound in stereo format, which uses two audio channels. The Dolby AC-3 standard outputs 5.1 channels, which includes 5 discrete audio channels plus a low frequency channel. In professional audio systems, audio systems with many audio channels are commonly used, and each of the audio channels can be sent to a unique speaker for output. When a computer sound card is used in an audio system, a sound chip in the sound card processes audio signals, and outputs the audio signals in the form of a number of audio channels. Each of these audio channels can then be sent to a speaker through a cable going from the sound card to each speaker. Any number of audio channels and corresponding speakers can be used with the sound card. Sound cards that can accommodate 2 channel, 5.1 channel, or 7.1 channel systems are commonly found.  
           [0005]    Please refer to FIG. 1. FIG. 1 is a block diagram of a wired professional audio system  10  according to the prior art. A sound card  12  is connected to a plurality of speakers  14 , which are positioned in various locations around a room. For example, FIG. 1 shows a front left speaker  14  and a rear right speaker  14 . These speakers  14  are stated as an example only, and any number of speakers  14  can be used. Typically, one speaker  14  is used for each channel provided by the wired professional audio system  10 . In addition to the speakers  14 , the sound card  12  can also be connected to a joystick  16  and to a microphone  18 , as is well known in the art.  
           [0006]    Unfortunately, not only does the setup for the wired professional audio system  10  require a large number of cables connected to the sound card  12 , but it also makes connecting the speakers  14 , the joystick  16 , and the microphone  18  much more troublesome. Care has to be taken to make sure speaker cables are positioned out of the way to allow easy movement around the wired professional audio system  10 . Moreover, if one of the speakers  14  is to be moved, care must be taken to ensure that the corresponding speaker cable is long enough to reach the new location of the speaker  14 . Speaker cables used in professional audio systems are very expensive, and can be 30 to 100 meters long. Moreover, speaker cables have to be carefully designed so that audio output is not affected by RLC characteristics of the cables. For example, suppose that a speaker has a power rating of 1000W with a resistance of 8 Ω. That means that the speaker cable leading to each speaker would have a high amount of current being carried through it. Since the frequency response for the speaker is desired to be above 20 kHz, that means that the total resistance of the speaker cable (including the two ends) has to be less than 1 Ω. Unfortunately, undesirable RLC effects of the speaker cable can affect the quality of the audio output, and adversely affect the frequency response.  
         SUMMARY OF INVENTION  
         [0007]    It is therefore a primary objective of the claimed invention to provide a multi-channel wireless audio system in order to solve the above-mentioned problems.  
           [0008]    According to the claimed invention, a multi-channel wireless audio system includes a sound card for a computer. The sound card includes a signal broadcasting circuit having a first transceiver for wirelessly transmitting digital audio signals to external speakers, a sound chip electrically connected to the signal broadcasting circuit for processing audio signals sent to the signal broadcasting circuit, and an interface connection for connecting the sound card to the computer. The audio system also has a plurality of wireless speaker modules, each including a second transceiver for receiving the wireless digital audio signals from the signal broadcasting circuit, a digital to analog converter for converting the digital audio signals into analog audio signals, an amplifier for amplifying the analog audio signals, and a speaker for converting the amplified analog audio signals into sound.  
           [0009]    It is an advantage of the claimed invention that the multi-channel wireless audio system does not need speaker cables to connect speakers to the sound card. This makes positioning the speakers much easier, and no speaker cables have to be hidden out of the way. Speakers can easily be moved to new positions without worrying about the length of speaker cables. Additionally, wirelessly broadcasting digital signals eliminates the need for expensive speaker cables that can adversely affect audio output characteristics, and wireless transmission does not lead to audio quality degradation.  
           [0010]    These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]    [0011]FIG. 1 is a block diagram of a wired professional audio system according to the prior art.  
         [0012]    [0012]FIG. 2 is a block diagram of a wireless professional audio system according to the present invention.  
         [0013]    [0013]FIG. 3 is a functional block diagram of a sound card of the wireless professional audio system.  
         [0014]    [0014]FIG. 4 is a functional block diagram of a single channel speaker module used in the wireless professional audio system.  
         [0015]    [0015]FIG. 5 is a functional block diagram of a multi-channel speaker module used in the wireless professional audio system.  
         [0016]    [0016]FIG. 6 is a functional block diagram of a joystick and a joystick adapter according to the present invention.  
         [0017]    [0017]FIG. 7 is a functional block diagram of a microphone and a microphone adapter according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0018]    Please refer to FIG. 2. FIG. 2 is a block diagram of a wireless professional audio system  20  according to the present invention. A sound card  22  contains an interface  30 , such as a PCI bus interface  30 , for interfacing with a host computer. A sound chip  24  is connected to the interface  30 , and is capable of processing sound and joystick signals. A signal broadcasting circuit  32  is connected to the sound chip  24 , and is used to wirelessly send multiple audio channels to corresponding speaker modules  34 . The signal broadcasting circuit  32  is also used to send and receive signals to and from a joystick  26 , and to receive signals from a microphone  28 . In the present invention, a joystick adapter  27  can be used to enable joystick  26  to be used to send and receive wireless signals to and from the signal broadcasting circuit  32 . Likewise, the microphone  28  can be outfitted with a microphone adapter  29  so that audio signals produced by the microphone can be wirelessly transmitted to the signal broadcasting circuit  32 .  
         [0019]    As with the example described in the prior art, the following description will assume that the wireless professional audio system  20  uses a plurality of audio channels and corresponding speaker modules  34 . Of course, the present invention can easily be extended to include any number of audio channels used in a professional audio system. With the present invention, the signal broadcasting circuit  32  receives audio signals from the sound chip  24 , and uses a transceiver  46  to wirelessly broadcast these audio signals to all speaker modules  34 . As will be described later, each speaker module  34  only produces sound generated by the audio channel corresponding to that speaker module  34 .  
         [0020]    Please refer to FIG. 3. FIG. 3 is a functional block diagram of the sound card  22  of the wireless professional audio system  20 . The sound chip  24  mixes audio signals, and separates the signals into distinct audio channels. Audio signals from each of the audio channels are then fed from the sound chip  24  into a multiplexer  36 . To minimize the complexity of the signal broadcasting circuit  32 , the multiplexer is used to select one audio channel at a time for processing and transmission. A sampling and control circuit  44  is used to select one of the inputted audio channels to be outputted from the multiplexer  36 . Signals from the selected audio channel are then converted into digital signals via an analog-to-digital converter (ADC)  38 . Operation of the ADC  38  is also controlled by the sampling and control circuit  44 . Digital audio signals are then sent from the ADC  38  to a processor  40  so that the signals can be appropriately packaged and compressed for wireless transmission, and the sampling and control circuit  44  helps to control operation of the processor  40 . Finally, the processor  40  sends the digital signals to the transceiver  46  for wireless transmission to the speaker modules  34 . During the packaging operation, a unique channel identifier is put into the packaged signals to denote which channel signal is being transmitted.  
         [0021]    In addition to outputting audio signals to speakers, the signal broadcasting circuit  32  is also used to receive audio signals from the microphone  28 . In this case, the transceiver  46  receives a digital form of the microphone  28  audio signals, and sends the signals to the processor  40 . The processor  40  then sends the digital audio signals to a digital-to-analog converter (DAC)  47 , which converts the microphone  28  signals into analog signals. Finally, the analog signals are sent to the sound chip  24  for proper processing of the microphone  28  audio signals.  
         [0022]    Likewise, the present invention sound card  22  is also capable of receiving control signals from the joystick  26 , and sending feedback signals back to the joystick  26 . When the sound card  22  receives control signals from the joystick  26 , the transceiver  46  sends the signals to the processor  40 . The processor  40  then sends these signals to a joystick control circuit  48  for proper processing of the signals from the joystick  26 . Finally, the processed control signals are then sent to the sound chip  24 , and the sound chip  24  can send control signals to the host computer through the PCI interface  30 . On the other hand, the host computer is capable of sending feedback signals to the joystick  26  by sending the signals through the opposite direction. In this case, the feedback signals would first be sent to the PCI bus interface  30 , the sound chip  24 , the joystick control circuit  48 , and the processor  40 . The processor  40  would then append an identifying code to the joystick feedback signals so that the joystick will be able to determine that the joystick is the appropriate target of the signals. Finally, the processor  40  sends the signals to the transceiver  46  for transmission to the joystick  26 .  
         [0023]    Although the joystick  26  and all speaker modules  34  will receive the transmitted wireless signals, only devices with a proper identifying code will be able to process signals containing this code. In order to broadcast signals for all audio channels to the speaker modules  34 , the sampling and control circuit  44  will take turns selecting different audio channels to be output from the multiplexer  36 . Moreover, the switching and transmission of each different audio channel is done quickly so that all audio channels can be broadcast to all speaker modules  34  in real time. In this way, all audio channels can be wirelessly transmitted to all speakers in the wireless professional audio system  20 . Likewise, whenever feedback signals need to be sent to the joystick  26 , the sampling and control circuit  44  will take turns between sending these feedback signals to the joystick  26  and sending audio signals to the speakers  34 .  
         [0024]    Please refer to FIG. 4. FIG. 4 is a functional block diagram of a single channel speaker module  34  used in the wireless professional audio system  20 . The basic structure of each speaker module  34  in the wireless professional audio system  20  is identical, so FIG. 4 can be used to represent each of the speaker modules  34 . A transceiver  50  is used to receive all wireless digital signals transmitted by the transceiver  46  of the signal broadcasting circuit  32 , and these signals are then sent to a processor  54  for appropriate processing. The processor  54  will then compare the channel identifier included in the received signals with a channel identifier stored in a channel selector  52 . If the identifier does not match, the speaker module  34  does no further processing on the received signals. If there is a match, the received digital signals are then sent to a digital-to-analog converter (DAC)  58  for conversion back into analog signals. A timing control circuit  56  communicates with the processor  54 , and helps control timing for operation of the processor  54  and the DAC  58 . Analog signals produced by the DAC  58  are then sent to a mono amplifier  60  for amplification before being sent to a speaker  64  that converts the amplified analog signals into sound. A diagnostic circuit  62  is used to notify the processor  54  of any problems that are detected in the operation of the mono amplifier  60  and the speaker  64 .  
         [0025]    The speaker module  34  shown in FIG. 4 is a single channel speaker, meaning that it is only capable of playing sounds from one audio channel. Please refer to FIG. 5. FIG. 5 is a functional block diagram of a multi-channel speaker module  134  used in the wireless professional audio system  20 . Operation of the multi-channel speaker module  134  is nearly identical to operation of the speaker module  34  shown in FIG. 4. The only difference is the addition of more channels to the speaker. As an example, the multi-channel speaker module  134  shown in FIG. 5 is a three-channel speaker, which produces low, medium, and high frequency sounds, but any number of channels could be used in the present invention.  
         [0026]    A transceiver  150  is used to receive all wireless digital signals transmitted by the signal broadcasting circuit  32 , and these signals are then sent to a processor  154  for processing. The processor  154  will then compare the channel identifier included in the received signals with a set of channel identifiers stored in a channel selector  152 . If the identifier does not match, the multi-channel speaker module  134  does no further processing on the received signals. If there is a match, the received digital signals are then sent to a DSP  157  for signal processing. Based on the channel identifier included with the received signals, the DSP  157  then sends the signals to one of three digital-to-analog converters (DACs)  158  for conversion back into analog signals. A timing control circuit  156  communicates with the processor  154 , and helps control timing for operation of the processor  154  and the DACs  158 . Analog signals produced by each DAC  1158  are then sent to a corresponding mono amplifier  160  for amplification before being sent to a corresponding speaker  164  that converts the amplified analog signals into sound. A diagnostic circuit  162  is used to notify the processor  154  of any problems that are detected in the operation of the mono amplifiers  160  and the speakers  164 .  
         [0027]    Please refer to FIG. 6. FIG. 6 is a functional block diagram of the joystick  26  and the joystick adapter  27  according to the present invention. The present invention uses the joystick adapter  27  so that a conventional joystick such as the joystick  26  can be used to wirelessly transmit to and receive control signals from the sound card  22 . The joystick adapter  27  contains a joystick port  70  for plugging the joystick  26  into the joystick adapter  27 . When the joystick  26  transmits control signals to the sound card  22 , the control signals are sent through the joystick port  70  to an ADC  72  for conversion into digital signals. The digital signals are then sent to a processor  75  for packaging, and then transmitted by a transceiver  78  to the signal broadcasting circuit  32  of the sound card  22 . On the other hand, when the joystick adapter  27  receives feedback signals from the sound card  22 , these signals are first received by the transceiver  78  and then sent to the processor  75 . The processor  75  will then check an identification code embedded in the feedback signals to see if the code matches an identification code stored in a device selector  76 . If the codes do not match, the joystick adapter  27  does nothing. If the codes do match, the processor  75  transmits the feedback signals to a DAC  74  for conversion into analog signals. These analog signals are then sent through the joystick port  70  to the joystick  26 . Thus, the joystick  26  can maintain bidirectional wireless communication with the sound card  22  through the use of the joystick adapter  27 .  
         [0028]    Please refer to FIG. 7. FIG. 7 is a functional block diagram of the microphone  28  and the microphone adapter  29  according to the present invention. The present invention uses the microphone adapter  29  so that a conventional microphone such as the microphone  28  can be used to wirelessly transmit audio signals to the sound card  22 . The microphone adapter  29  contains a microphone port  80  for plugging the microphone  28  into the microphone adapter  29 . When the microphone  28  transmits audio signals to the sound card  22 , the audio signals are sent through the microphone port  80  to an ADC  82  for conversion into digital signals. The digital signals are then sent to a processor  85  for packaging, and then transmitted by a transceiver  86  to the signal broadcasting circuit  32  of the sound card  22 . A timing control circuit  84  communicates with the processor  85 , and helps control timing for operation of the processor  85  and the ADC  82 . Thus, the microphone  28  can wirelessly transmit audio signals to the sound card  22  through the use of the microphone adapter  29 .  
         [0029]    In a preferred embodiment of the present invention, all wireless signals used in communication between the transceiver of the signal broadcasting circuit and the transceivers of the speaker modules, the joystick, and the microphone are direct sequence spread spectrum (DSSS) signals that conform to the IEEE 802.11b networking standard.  
         [0030]    Compared to the prior art, the wireless professional audio system is able to send audio signals from the signal broadcasting circuit of the sound card to speaker modules via wireless transmission, eliminating the need for speaker cables to connect audio processing circuitry with speakers. In addition, the present invention sound card can also be used to support a wireless microphone and a wireless joystick. Transceivers are used in the speaker modules, the joystick, the microphone, and the signal broadcasting circuit of the sound card to facilitate the wireless communication. The flexibility that wireless transmission provides makes positioning the speakers much easier, and speakers can easily be moved to new positions without worrying about the constraint of speaker cables. Additionally, wirelessly broadcasting digital signals eliminates the need for expensive speaker cables that can adversely affect audio output characteristics, and wireless transmission does not lead to audio quality degradation.  
         [0031]    Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.