Abstract:
Disclosed is a wireless audio transfer system. The wireless audio transfer system includes an audio transmitting apparatus including a microphone and a modulating/transmitting unit for transmitting radio waves modulated using an audio signal from the microphone, an audio receiving apparatus including a receiving/demodulating unit for receiving the radio waves transmitted from the audio transmitting apparatus and demodulating the audio signal and an audio output terminal for outputting the audio signal demodulated by the receiving/demodulating unit, and an image pickup apparatus including an audio input terminal for inputting the audio signal outputted from the audio receiving apparatus. In this wireless audio transfer system of the embodiment, the audio transmitting apparatus includes a connection terminal and a data transmitting unit, the audio receiving apparatus includes a first communication terminal and a data processing unit, and the image pickup apparatus includes a second communication terminal and a control unit.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present invention contains subject matter related to Japanese Patent Application JP 2007-098597 filed in the Japanese Patent Office on Apr. 4, 2007, the entire contents of which being incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a system that uses a wireless microphone to transfer audio to an image pickup apparatus, a recording apparatus, or an audio mixer, and to a wireless microphone, an audio transmitting apparatus, an audio receiving apparatus, an image pickup apparatus, a recording apparatus, and an audio mixer that include such a system. 
         [0004]    2. Description of the Related Art 
         [0005]    In recent years, when news broadcasts and the like are filmed on location, it has become increasingly common to record audio transferred using wireless microphones.  FIGS. 1A and 1B  show the appearance of two examples of a wireless microphone.  FIG. 1A  shows wireless microphone transmitters (hereinafter simply “transmitters”) as apparatuses for transmitting audio. Each of the transmitters  81 ,  82  fundamentally includes a microphone (in the case of the transmitter  82 , a pin microphone, not shown, that is connected by a cable) and a modulating/transmitting unit that transmits radio waves that have been modulated using an audio signal from the microphone. The transmitter  81  is a hand microphone-type transmitter that is held by hand. Conversely, the transmitter  82  is a transmitter that is attached to a waist belt or the like. 
         [0006]      FIG. 1B  shows a wireless microphone receiver (hereinafter simply “receiver”) as the apparatus for receiving the audio. The receiver  83  fundamentally includes a receiving/demodulating unit that receives radio waves transmitted from the transmitter  81  or transmitter  82  and demodulates the audio signal and an output terminal that outputs the demodulated audio signal to the outside. 
         [0007]      FIGS. 2A and 2B  are diagrams showing examples of an audio transfer system that uses the transmitter  81  and the receiver  83  shown in  FIGS. 1A and 1B  to record audio during ENG (Electronic News Gathering). In the example in  FIG. 2A , the transmitter  81  is used by a reporter conducting an interview. The receiver  83  is attached to a slot provided on a camcorder  91  (i.e., a camcorder integrated with a recorder such as a VTR or optical disk apparatus) or is connected to the camcorder  91  by a cable. The audio signal inputted from the receiver  83  into the camcorder  91  is recorded by the camcorder  91  together with the images picked up by the camcorder  91 . 
         [0008]    In the example in  FIG. 2B , the transmitter  81  is used by a reporter and the receiver  83  is connected by a cable to an audio mixer  92 . The audio signal inputted from the receiver  83  into the audio mixer  92  is mixed or switched inside the audio mixer  92  and the audio signal outputted from the audio mixer  92  is recorded by a VTR or audio recorder or camcorder, not shown. 
         [0009]    In the past, for a wireless microphone such as the examples shown in  FIGS. 1A and 1B , a circuit that emits a tone signal of a predetermined frequency outside the audible spectrum is provided inside the transmitter, such tone signal is superimposed on an audio signal and transmitted from the transmitter, and a circuit that detects this tone signal is provided inside the receiver, so that information can be transmitted as described below, for example.
   The receiver identifies the radio waves from the transmitter and distinguishes the waves from interference   The receiver is informed of a drop in the voltage of a battery inside the transmitter and an indicator on the receiver is lit   
 
         [0012]    In the past, to reduce in size of this kind of wireless microphone, the transmitter and the receiver have been provided with only a minimal number of operation buttons for carrying out setting operations of the respective devices. 
         [0013]    Moreover, for this type of wireless microphone, Japanese Unexamined Patent Application Publication No. 2007-36735 has disclosed a technology where the receiver detects unused frequencies in the radio waves based on the reception level of the radio waves and outputs information showing the detected unused frequencies to a camcorder or audio mixer (such information being displayed by the camcorder or audio mixer) so that the operator of the camcorder or audio mixer can check which frequencies are unused and set the frequency to be used by the wireless microphone. 
       SUMMARY OF THE INVENTION 
       [0014]    In this way, although a tone signal is superimposed on an audio signal and transmitted by an existing wireless microphone, such tone signal is only used to distinguish the signal from interference and/or to give a warning of a drop in battery voltage. 
         [0015]    Also, with an audio transfer system that uses an existing wireless microphone, such as those shown in  FIGS. 2A and 2B , the camcorder or audio mixer is operated either by a specialist operator (such as a cameraman or soundman) other than the reporter or, when the reporter carries out filming alone without such an operator being present, by the reporter himself or herself walking up to the camcorder or audio mixer. 
         [0016]    However, since the reporter has to walk up to the camcorder or audio mixer every time an operation is made, this results in poor operability and can prevent filming from proceeding smoothly. On the other hand, when a specialist operator makes such operations, there is an increase in the number of staff required by filming. 
         [0017]    As one method of having a reporter who is filming alone make such operations without having to walk up to the camcorder or audio mixer, it would be conceivable to provide dedicated operation buttons for remote operation of the camcorder or audio mixer on the transmitter. 
         [0018]    However, if such dedicated operation buttons are added to the transmitter, this would obstruct the ongoing progress in the miniaturization of wireless microphones. 
         [0019]    On the other hand, if small buttons were provided as such dedicated operation buttons to keep the transmitter small, operability would still be poor. 
         [0020]    When such dedicated operation buttons are provided to add a new function (i.e., to make remote operation possible), there is a resulting increase in the number of operation buttons, which makes the configuration of operation system more complex and can lead to erroneous operations. 
         [0021]    Also, the disclosed technology in Japanese Unexamined Patent Application Publication No. 2007-36735 enables the operator of a camcorder or audio mixer to set the frequency used by a wireless microphone and is not a technology for making it easy for the user of a transmitter (such as a reporter) to operate a camcorder or audio mixer. 
         [0022]    According to embodiments of the present invention, for an audio transfer system, such as those shown in  FIGS. 2A and 2B  where an audio signal is inputted from a wireless microphone into an image pickup apparatus, recording apparatus, or audio mixer, aims to improve the operability when a user who is using a transmitter operates the image pickup apparatus, recording apparatus, or audio mixer, while keeping the wireless microphone small. 
         [0023]    A wireless audio transfer system according to an embodiment of the present invention includes 
         [0024]    an audio transmitting apparatus including a microphone and a modulating/transmitting unit for transmitting radio waves modulated using an audio signal from the microphone, 
         [0025]    an audio receiving apparatus including a receiving/demodulating unit for receiving the radio waves transmitted from the audio transmitting apparatus and demodulating the audio signal and an audio output terminal for outputting the audio signal demodulated by the receiving/demodulating unit, and 
         [0026]    an image pickup apparatus including an audio input terminal for inputting the audio signal outputted from the audio receiving apparatus. 
         [0027]    In this wireless audio transfer system of the embodiment, the audio transmitting apparatus includes 
         [0028]    a connection terminal for connecting a human interface device and a data transmitting unit for transmitting, as radio waves, data corresponding to an operation of the human interface device connected to the connection terminal, 
         [0029]    the audio receiving apparatus includes a first communication terminal and a data processing unit for obtaining the data from the received radio waves and outputting a control signal corresponding to the data from the first communication terminal, and 
         [0030]    the image pickup apparatus includes a second communication terminal for inputting the control signal outputted from the first communication terminal of the audio receiving apparatus and a control unit for controlling an inside of the image pickup apparatus in accordance with the control signal inputted into the second communication terminal. 
         [0031]    Another wireless audio transfer system according to an embodiment of the present invention includes 
         [0032]    an audio transmitting apparatus including a microphone and a modulating/transmitting unit for transmitting radio waves modulated using an audio signal from the microphone, 
         [0033]    an audio receiving apparatus including a receiving/demodulating unit for receiving the radio waves transmitted from the audio transmitting apparatus and demodulating the audio signal and an audio output terminal for outputting the audio signal demodulated by the receiving/demodulating unit, and 
         [0034]    a recording apparatus including an audio input terminal for inputting the audio signal outputted from the audio receiving apparatus. 
         [0035]    In this wireless audio transfer system of the embodiment, the audio transmitting apparatus includes 
         [0036]    a connection terminal for connecting a human interface device and a data transmitting unit for transmitting, as radio waves, 
         [0037]    data corresponding to an operation of the human interface device connected to the connection terminal, 
         [0038]    the audio receiving apparatus includes a first communication terminal and a data processing unit for obtaining the data from the received radio waves and outputting a control signal corresponding to the data from the first communication terminal, and 
         [0039]    the recording apparatus includes a second communication terminal for inputting the control signal outputted from the first communication terminal of the audio receiving apparatus and a control unit for controlling an inside of the recording apparatus in accordance with the control signal inputted into the second communication terminal. 
         [0040]    Yet another wireless audio transfer system according to an embodiment of the present invention includes 
         [0041]    an audio transmitting apparatus including a microphone and a modulating/transmitting unit for transmitting radio waves modulated using an audio signal from the microphone, 
         [0042]    an audio receiving apparatus including a receiving/demodulating unit for receiving the radio waves transmitted from the audio transmitting apparatus and demodulating the audio signal and an audio output terminal for outputting the audio signal demodulated by the receiving/demodulating unit, and 
         [0043]    an audio mixer including an audio input terminal for inputting the audio signal outputted from the audio output terminal of the audio receiving apparatus. In this wireless audio transfer system of the embodiment, the audio transmitting apparatus includes 
         [0044]    a connection terminal for connecting a human interface device and a data transmitting unit for transmitting, as radio waves, 
         [0045]    data corresponding to an operation of the human interface device connected to the connection terminal, 
         [0046]    the audio receiving apparatus includes a first communication terminal and a data processing unit for obtaining the data from the received radio waves and outputting a control signal corresponding to the data from the first communication terminal, and 
         [0047]    the audio mixer includes a second communication terminal for inputting the control signal outputted from the first communication terminal of the audio receiving apparatus and a control unit for controlling an inside of the audio mixer in accordance with the control signal inputted into the second communication terminal. 
         [0048]    An embodiment of the present invention further includes a wireless microphone, audio transmitting apparatus, audio receiving apparatus, image pickup apparatus, recording apparatus, and audio mixer that include any of the wireless audio transfer systems described above. 
         [0049]    According to an embodiment of the present invention, an audio transmitting apparatus (or “transmitter”) that includes a wireless microphone includes a connection terminal for connecting a human interface device. By connecting a human interface device to such connection terminal and operating the device, data corresponding to such operation is transmitted as radio waves by a data transmitting unit inside the audio transmitting apparatus. 
         [0050]    In the audio receiving device (or “receiver”), the data processing unit obtains data from the radio waves received from the audio transmitting apparatus and a control signal corresponding to such data is outputted from the communication terminal. 
         [0051]    In an image pickup apparatus, recording apparatus, or audio mixer into which an audio signal is inputted using this wireless microphone, the control signal from the audio receiving apparatus is inputted into a communication terminal. A control unit of the image pickup apparatus, recording apparatus, or audio mixer controls the inside of the image pickup apparatus, recording apparatus, or audio mixer in accordance with this control signal. 
         [0052]    Consequently, the user who uses the audio transmitting apparatus can remotely operate the image pickup apparatus, recording apparatus, or audio mixer using the human interface device connected to the audio transmitting apparatus. 
         [0053]    On the human interface device connected to the audio transmitting apparatus, the number of operation buttons can optionally be increased or decreased in accordance with how the system is used. When complex operations are carried out, a device with a large number of operation buttons may be used, such as a keyboard. Conversely, when simple operations are carried out, a device with around one or two operation buttons may be used, such as a mouse. 
         [0054]    Since it is possible to select a device of a size and form that is easy for the user to operate as the human interface device, it is possible for the user to make operations using his or her preferred control device. 
         [0055]    In addition, since operation buttons for remote operation are not provided on the audio transmitting apparatus itself, the size of the wireless microphone can be kept small as those in the related art. 
         [0056]    Consequently, in an audio transfer system where an audio signal is inputted from a wireless microphone into an image pickup apparatus, recording apparatus, or audio mixer, it is possible to keep the wireless microphone small while improving operability when the user using the audio transmitting apparatus (or “transmitter”) operates a camcorder, recording apparatus, or audio mixer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0057]      FIGS. 1A and 1B  are views showing the appearance of wireless microphones; 
           [0058]      FIGS. 2A and 2B  are views showing examples of audio transfer systems that use a wireless microphone; 
           [0059]      FIG. 3  is a view showing an example of an audio transfer system to which an embodiment of the present invention has been applied; 
           [0060]      FIG. 4  is a block diagram showing an example configuration of a transmitter and a receiver shown in  FIG. 3 ; 
           [0061]      FIG. 5  is a diagram showing an example of table data stored by a microcomputer inside the transmitter in the system shown in  FIG. 3 ; 
           [0062]      FIG. 6  is a block diagram showing the overall configuration of a camcorder shown in  FIG. 3 ; 
           [0063]      FIG. 7  is a view showing another example of an audio transfer system to which an embodiment of the present invention has been applied; 
           [0064]      FIG. 8  is a diagram showing an example of table data stored by a microcomputer inside a transmitter in the system shown in  FIG. 7 ; 
           [0065]      FIG. 9  is a block diagram showing the overall configuration of an audio mixer shown in  FIG. 7 ; 
           [0066]      FIG. 10  is a block diagram showing another example configuration of the transmitter and the receiver shown in  FIG. 3 ; 
           [0067]      FIGS. 11A and 11B  are diagrams showing examples of table data stored by microcomputers inside the transmitter and the receiver in the example shown in  FIG. 10 ; 
           [0068]      FIG. 12  is a block diagram showing yet another example configuration of the transmitter and the receiver shown in  FIG. 3 ; 
           [0069]      FIG. 13  is a block diagram showing yet another example configuration of the transmitter and the receiver shown in  FIG. 3 ; and 
           [0070]      FIG. 14  is a block diagram showing an example configuration of an audio mixer in which a receiver is installed. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0071]    Preferred embodiments of the present invention will now be described in detail with reference to the attached drawings. Note that two systems, which are an audio transfer system for inputting an audio signal from a wireless microphone into a camcorder and an audio transfer system for inputting an audio signal from a wireless microphone into an audio mixer, will be described. 
       [System for Inputting Audio Signals Into a Video Camera] 
       [0072]    System  FIG. 3  is a diagram showing one example of an audio transfer system to which an embodiment of the present invention has been applied. This system inputs audio transferred using a wireless microphone into a camcorder (i.e., a video camera integrated with a recorder such as a VTR or optical disk apparatus) in order to record audio during ENG (Electronic News Gathering).  FIG. 3  is a diagram showing one example of an audio transfer system to which an embodiment of the present invention has been applied. This system inputs audio transferred using a wireless microphone into a camcorder (i.e., a camcorder integrated with a recorder such as a VTR or optical disk apparatus) in order to record audio during ENG (Electronic News Gathering). 
         [0073]    A wireless microphone transmitter (hereinafter simply “transmitter”) is used by a reporter conducting an interview. Although a hand microphone-type transmitter is shown as the transmitter  1  in  FIG. 3 , the transmitter  1  may be a device that is attached to a waist belt or the like (a device of the same form as the transmitter  82  shown in  FIG. 1A ). 
         [0074]    The wireless microphone receiver (hereinafter, simply called “receiver”)  2  is attached to a slot provided on the camcorder  3  (or is attached to the camcorder  3  by a cable). The audio signal transferred to the receiver  2  from the transmitter  1  is inputted into the camcorder  3  from the receiver  2  and is recorded by the camcorder  3  together with the images picked up by the camcorder  3 . 
         [0075]    In the present system, when the reporter is filming alone by himself/herself by himself/herself while reporting, the reporter clicks a USB (Universal Serial Bus)-compliant mouse  4  that the reporter has at hand to remotely operate the camcorder  3 . Next, the configuration of the transmitter  1  and the receiver  2  that make it possible to operate the camcorder  3  according to this method will be described. 
         [0076]      FIG. 4  is a block diagram that shows example configurations of the transmitter  1  and the receiver  2 . In the examples, the transmitter  1  and the receiver  2  includes a digital wireless microphone. 
         [0077]    The transmitter  1  includes a microphone  10 , an A/D converter  11  that carries out analog/digital conversion on an audio signal from the microphone  10 , a packetizing circuit  12  that converts the digital audio signal from the A/D converter  11  to packets, a modulating circuit  13  that transmits radio waves modulated using the packet signal outputted from the packetizing circuit  12 , an amp  14 , and a transmission antenna  15 . When the transmitter  1  is attached to a waist belt or the like, the microphone  10  is a pin microphone connected by a cable. 
         [0078]    In addition, the transmitter  1  includes an USB terminal  16  and a microcomputer  17 . 
         [0079]    The microcomputer  17  stores a program that provides the transmitter  1  with a USB host function. 
         [0080]    The microcomputer  17  also stores a program that generates a packet signal appended with control data corresponding to an operation of a USB-compliant human interface device (such as a mouse or keyboard) connected to the USB terminal  16  as a program for controlling the packetizing circuit  12 . 
         [0081]    Table data such as that shown in  FIG. 5  for associating a left click with control data showing “start recording” and associating a right click with control data showing “stop recording” is provided in the control program for the packetizing circuit  12  as table data showing the correspondence between operations of the mouse and control data. 
         [0082]    The receiver  2  includes a reception antenna  18 , an amp  19 , a demodulating circuit  20  that receive radio waves transmitted from the transmitter  1  and demodulate the packet signal, an unpacketizing circuit  21  that extracts the digital audio signal and the control data from the packet signal demodulated by the demodulating circuit  20 , a D/A converter  22  that carries out digital/analog conversion on the digital audio signal extracted by the unpacketizing circuit  21 , and an audio output terminal  23  that outputs an analog audio signal from the D/A converter  22 . 
         [0083]    The receiver  2  is also equipped with a microcomputer  24  and a communication terminal  25  for serial communication. 
         [0084]    The control data extracted by the unpacketizing circuit  21  is sent to the microcomputer  24 . The microcomputer  24  outputs a control signal, which indicates an operation shown by the control data, from the communication terminal  25 . 
         [0085]      FIG. 6  is a block diagram showing the overall configuration of the camcorder  3  shown in  FIG. 3 . Since the parts of the camcorder  3  labeled as “image pickup system  41 ”, “image signal processing system  42 ”, “audio signal processing system  43 ”, and “recording/reproduction system  44 ” have the same hardware configurations as in a standard camcorder, such parts have been simplified in the drawing. 
         [0086]    The camcorder  3  is also equipped with an audio input terminal  45  for inputting an analog audio signal outputted from the audio output terminal  23  (shown in  FIG. 4 ) of the receiver  2  and a communication terminal  46  for inputting a control signal outputted from the communication terminal  25  (shown in  FIG. 4 ) of the receiver  2 . 
         [0087]    The analog audio signal inputted into the audio input terminal  45  is sent to the audio signal processing system  43 . The control signal inputted into the communication terminal  46  is sent to a microcomputer  47  for carrying out internal control of the camcorder  3 . 
         [0088]    When the control signal indicates “start recording”, in the same way as when a start recording operation has been carried out using an operation panel (not shown) of the camcorder  3 , the microcomputer  47  controls the image signal processing system  42 , the audio processing system  43 , and the recording/reproduction system  44  to start the recording of images and audio. 
         [0089]    On the other hand, when the control signal indicates “stop recording”, in the same way as when a stop recording operation has been carried out using the operation panel, the microcomputer  47  controls the image signal processing system  42 , the audio processing system  43 , and the recording/reproduction system  44  to stop the recording of images and audio. 
         [0090]    In the system shown in  FIG. 3 , when the reporter who uses the transmitter  1  left-clicks the mouse  4  in a state where the mouse  4  is connected to the USB terminal  16  (see  FIG. 4 ) of the transmitter  1 , control data showing the start of recording is transmitted from the transmitter  1  as radio waves. Conversely, when the reporter right-clicks the mouse  4 , control data showing a stopping of recording is transmitted from the transmitter  1  as radio waves. 
         [0091]    In the receiver  2 , the control data is obtained from the radio waves received from the transmitter  1  and a control signal, which indicates an operation shown by the control data, is outputted from the communication terminal  25 . 
         [0092]    In the camcorder  3 , based on the control signal inputted into the communication terminal  46  from the receiver  2 , the microcomputer  47  controls the starting and stopping of recording. 
         [0093]    Consequently, the reporter using the transmitter  1  can remotely control the camcorder  3  using the mouse  4  connected to the transmitter  1 . 
       [System for Inputting Audio Signals Into an Audio Mixer] 
       [0094]      FIG. 7  is a diagram showing another example of an audio transfer system to which an embodiment of the present invention has been applied. In this system, to record audio during ENG (Electronic News Gathering), audio transferred using a wireless microphone is inputted into an audio mixer. 
         [0095]    In this system, since the transmitter  1  and the receiver  2  have the same hardware configurations (see  FIG. 4 ) as in the system shown in  FIG. 3 , the same reference numerals have been assigned as in  FIG. 3 . 
         [0096]    Here also, the microcomputer  17  in the transmitter  1  (see  FIG. 4 ) stores a program that provides the transmitter  1  with a USB host function and also stores a program that generates a packet signal appended with control data corresponding to an operation of a USB-compliant human interface device connected to the USB terminal  16  (see  FIG. 4 ) as a program for controlling the packetizing circuit  12 . 
         [0097]    In the system shown in  FIG. 7 , the transmitter  1  is used by a reporter conducting an interview. The receiver  2  is connected by a cable to the audio mixer  5 . The audio signal inputted into the audio mixer  5  from the receiver  2  is mixed or switched inside the audio mixer  5  and an audio signal outputted from the audio mixer  5  is recorded in a VTR (or an audio recorder or camcorder), not shown. 
         [0098]    In this system, when the reporter is filming alone by himself/herself while reporting, the reporter remotely controls the audio mixer  5  by operating a USB-compliant keyboard  6  that the reporter has at hand. 
         [0099]    Consequently, the program for controlling the packetizing circuit  12  stored in the microcomputer  17  inside the transmitter  1  is provided, as table data showing the correspondence between operations of the keyboard and control data, with table data such as that shown in  FIG. 8 . According to the table, an operation of an up cursor key labeled “↑” is associated with control data showing a raising of output volume, an operation of a down cursor key labeled “↓” is associated with control data showing a lowering of output volume, an operation of a right cursor key labeled “→” is associated with control data showing a raising of input volume, an operation of a left cursor key labeled “←” is associated with control data showing a lowering of input volume, an operation of the “1” key on a ten-key pad is associated with control data showing mixing of an audio signal, and an operation of the “2” key on a ten-key pad is associated with control data showing no mixing of an audio signal. 
         [0100]      FIG. 9  is a block diagram showing the overall configuration of the audio mixer  5  shown in  FIG. 7 . The audio mixer  5  is an audio mixer that can mix audio signals on four channels and includes four audio input terminals  51   a  to  51   d.    
         [0101]    Audio signals inputted into the audio input terminals  51   a  to  51   d  are supplied to a mixing amp  55  via amps  52   a  to  52   d,  variable volume controls (faders)  53   a  to  53   d,  and switches  54   a  to  54   d  that can be switched on or off. The output audio signal from the mixing amp  55  is outputted via a variable volume control  56  from an audio output terminal  57 . 
         [0102]    On the audio mixer  5 , serial communication terminals  58   a  to  58   d  of the same specification as the communication terminal  25  (see  FIG. 4 ) of the receiver  2  are provided so as to correspond one-to-one with the four audio input terminals  51   a  to  51   d.    
         [0103]    The audio output terminal  23  and communication terminal  25  (see  FIG. 4 ) of the receiver  2  are connected to a corresponding audio input terminal and communication terminal out of the audio input terminals  51   a  to  51   d  and communication terminals  58   a  to  58   d  by cables (for example, when the audio output terminal  23  is connected to the audio input terminal  51   a,  the communication terminal  25  is connected to the communication terminal  58   a ). 
         [0104]    The control signal inputted into the communication terminals  58   a  to  58   d  is sent to the microcomputer  59  that carries out internal control of the audio mixer  5 . 
         [0105]    When the control signal indicates a raising of the output volume, in the same way as when an operation that raises the output volume has been made via the operation panel (not shown) of the audio mixer  5 , the microcomputer  59  controls the variable volume control  56  to raise the output volume. 
         [0106]    When the control signal indicates a lowering of the output volume, in the same way as when an operation that lowers the output volume has been made via the operation panel, the microcomputer  59  controls the variable volume control  56  to lower the output volume. 
         [0107]    When the control signal indicates a raising of the input volume, in the same way as when an operation that raises the input volume has been made via the operation panel, the microcomputer  59  controls the variable volume control, out of the variable volume controls  53   a  to  53   d,  supplied with the audio signal inputted into the audio input terminal corresponding to the communication terminal in which the control signal was inputted (for example, the variable volume control  53   a  when a control signal has been inputted into the communication terminal  58   a ) to raise the input volume. 
         [0108]    When the control signal indicates a lowering of the input volume, in the same way as when an operation that lowers the input volume has been made via the operation panel, the microcomputer  59  controls the variable volume control, out of the variable volume controls  53   a  to  53   d,  supplied with the audio signal inputted into the audio input terminal corresponding to the communication terminal in which the control signal was inputted to lower the input volume. 
         [0109]    When the control signal indicates mixing of an audio signal, in the same way as when an operation that indicates mixing of an audio signal from the transmitter  1  has been made via the operation panel, the microcomputer  59  switches on the switch, out of the switches  54   a  to  54   d,  supplied with the audio signal inputted into the audio input terminal corresponding to the communication terminal in which the control signal was inputted (for example, the switch  54   a  when a control signal was inputted into the communication terminal  58   a ). 
         [0110]    When the control signal indicates no mixing of an audio signal, in the same way as when an operation that indicates no mixing of an audio signal from the transmitter  1  has been made via the operation panel, the microcomputer  59  switches off the switch, out of the switches  54   a  to  54   d,  supplied with an audio signal inputted into the audio input terminal corresponding to the communication terminal in which the control signal was inputted. 
         [0111]    In the system shown in  FIG. 7 , when the reporter using the transmitter  1  presses the up cursor key labeled “↑” on the keyboard  6  in a state where the keyboard  6  is connected to the USB terminal  16  of the transmitter  1  (see  FIG. 4 ), control data showing a raising of the output volume is transmitted from the transmitter  1  as radio waves. Conversely when the reporter presses the down cursor key labeled “↓” on the keyboard  6 , control data showing a lowering of the output volume is transmitted from the transmitter  1  as radio waves. 
         [0112]    Similarly, when the reporter presses the right cursor key labeled “→” on the keyboard  6 , control data showing a raising of the input volume is transmitted from the transmitter  1  as radio waves. Also, when the reporter presses the left cursor key labeled “←” on the keyboard  6 , control data showing a lowering of the input volume is transmitted from the transmitter  1  as radio waves. 
         [0113]    Also, when the reporter presses the “1” key on a ten-key pad on the keyboard  6 , control data showing mixing is transmitted from the transmitter  1  as radio waves. When the reporter presses the “2” key on a ten-key pad on the keyboard  6 , control data showing no mixing is transmitted from the transmitter  1  as radio waves. 
         [0114]    In the receiver  2 , the control data is obtained from the radio waves received from the transmitter  1  and a control signal, which indicates an operation shown by the control data, is outputted from the communication terminal  25 . 
         [0115]    In the audio mixer  5 , based on the control signal inputted from the receiver  2 , the microcomputer  59  controls the output volume, the input volume of the audio signal from the receiver  2 , or whether the audio signal from the receiver  2  is to be mixed. 
         [0116]    Consequently, the reporter using the transmitter  1  can remotely operate the audio mixer  5  using the keyboard  6  connected to the transmitter  1 . 
         [0117]    As described above, in an audio transfer system to which an embodiment of the present invention has been applied, the reporter that uses the transmitter  1  can remotely operate a camcorder or audio mixer using a common human interface device (for example, a mouse or keyboard) connected to the transmitter  1 . 
         [0118]    Here, on the human interface device connected to the transmitter  1 , the number of operation buttons can optionally be increased or decreased in accordance with how the system is used. When complex operations are carried out, a device with a large number of operation buttons may be used, such as the keyboard  6  in the system shown in  FIG. 7 . Conversely, when simple operations are carried out, a device with around one or two operation buttons may be used, such as the mouse  4  in the system shown in  FIG. 7 . 
         [0119]    Since it is possible to select a device of a size and form that is easy for the user to operate out of commercially available devices as the mouse or keyboard connected to the transmitter  1 , it is possible for the user to make operations using his or her preferred control device. 
         [0120]    In addition, since operation buttons for remote operation are not provided on the transmitter  1  itself, the size of the wireless microphone can be kept small as in the past. 
         [0121]    Consequently, in an audio transfer system where an audio signal is inputted from a wireless microphone into a camcorder or audio mixer, it is possible to keep the wireless microphone small while improving operability when the user using the transmitter  1  operates the camcorder or audio mixer. 
         [0122]    Next, examples of alternative configurations of the transmitter  1  and the receiver  2  described above (i.e., alternatives to the configurations shown in  FIG. 4 ) will be described with reference to  FIGS. 10 to 13 . 
         [0123]      FIG. 10  is a block diagram showing other example configurations of the transmitter  1  and the receiver  2 . Parts that are the same as in  FIG. 4  are assigned the same reference numerals. In this example also, the transmitter  1  and the receiver  2  include a digital wireless microphone. 
         [0124]    The transmitter  1  is also provided with a modulating circuit  26 , an amp  27 , and a transmission antenna  28  for transmitting a subcarrier of a different frequency band to a main carrier, the main carrier being the radio waves transmitted by the modulating circuit  13 , the amp  14 , and the transmission antenna  15 . 
         [0125]    In this example also, a program that provides the transmitter  1  with a USB host function is stored in the microcomputer  17 . In this example, the microcomputer  17  supplies control data (control data such as that shown in  FIGS. 5  or  8 ) corresponding to an operation of a USB-compliant human interface device connected to the USB terminal  16  to the modulating circuit  26  so that the control data is transmitted as the subcarrier from the transmission antenna  28 . 
         [0126]    In addition to the reception antenna  18 , the amp  19 , and the demodulating circuit  20 , the receiver  2  includes a reception antenna  29 , an amp  30 , and a demodulating circuit  31  to receive the subcarrier transmitted from the transmitter  1  and demodulate the control signal. 
         [0127]    The control data demodulated by the demodulating circuit  31  is sent to the microcomputer  24 . The microcomputer  24  outputs a control signal, which indicates an operation shown by the control data, from the communication terminal  25 . 
         [0128]      FIG. 11  is a block diagram showing other example configurations of the transmitter  1  and the receiver  2 . Parts that are the same as in  FIG. 4  are assigned the same reference numerals. In this example, the transmitter  1  and the receiver  2  transfer an analog audio signal. 
         [0129]    The transmitter  1  includes a tone signal generating circuit  32 , which generates a tone signal of a frequency outside the audible spectrum, and an adding circuit  33 . 
         [0130]    Here also, a program that provides the transmitter  1  with a USB host function is stored in the microcomputer  17 . 
         [0131]    A program for causing the tone signal generating circuit  32  to generate a tone signal of a frequency corresponding to an operation of a USB-compliant human interface device connected to the USB terminal  16  is also stored in the microcomputer  17  as a program for controlling the tone signal generating circuit  32 . 
         [0132]    Table data, such as that shown in  FIG. 12A  for example, that associates a left click with a tone signal of a specified frequency F 1  outside the audible spectrum and associates a right click with a tone signal of a specified frequency F 2  (≠F 1 ) outside the audible spectrum is provided in the program for controlling the tone signal generating circuit  32  as table data showing the correspondence between operations of the mouse and tone signals. 
         [0133]    The tone signal generated by the tone signal generating circuit  32  is superimposed on the audio signal from the microphone  10  by the adding circuit  33  and is sent to the modulating circuit  13 . 
         [0134]    The receiver  2  includes a tone signal detecting circuit  34  that detects the tone signal from the audio signal demodulated by the demodulating circuit  20 . The tone signal detected by the tone signal detecting circuit  34  is sent to the microcomputer  24 . 
         [0135]    Table data, such as that shown in  FIG. 12B  for example, that associates a tone signal of the frequency F 1  with control data indicating a start of recording and associates a tone signal of the frequency F 2  with control data indicating a stopping of recording is provided in the microcomputer  24 . 
         [0136]    The microcomputer  24  outputs a control signal, which indicates an operation shown by the control data read from the table data corresponding to a frequency of the tone signal from the tone signal detecting circuit  34 , from the communication terminal  25 . 
         [0137]    Note that table data for remotely operating the camcorder  3  shown in  FIG. 3  are shown in  FIGS. 12A and 12B  in the same way, and table data that link respective operations and control data using tone signals of predetermined frequencies are also provided as table data for remotely operating the audio mixer  5  shown in  FIG. 7 . 
         [0138]      FIG. 13  is a block diagram showing other example configurations of the transmitter  1  and the receiver  2 . Parts that are the same as in  FIG. 4  and  FIG. 10  are assigned the same reference numerals. In this example also, the transmitter  1  and the receiver  2  transfer an analog audio signal. 
         [0139]    In this example also, a program that provides the transmitter  1  with a USB host function is stored in the microcomputer  17 . In this example, the microcomputer  17  supplies control data (control data such as that shown in  FIG. 5  and  FIG. 8 ) corresponding to an operation of a USB-compliant human interface device connected to the USB terminal  16  to the modulating circuit  26  so that the control data is transmitted from the transmission antenna  28  as a subcarrier. 
         [0140]    In the receiver  2 , the control data demodulated by the demodulating circuit  31  is sent to the microcomputer  24 . The microcomputer  24  outputs a control signal indicating the operation shown by the control data from the communication terminal  25 . 
         [0141]    Even if the configurations described with reference to  FIG. 10  to  FIG. 13  are used for the transmitter  1  and the receiver  2 , it will still be possible to remotely operate the camcorder  3  shown in  FIG. 3  or the audio mixer  5  shown in  FIG. 5  using a USB-compliant mouse or keyboard connected to the transmitter  1 . 
         [0142]    Note that the correspondence between operations of the mouse or keyboard and the control data shown in  FIG. 5  or  FIG. 8  in the description above are merely examples, and by changing the table data provided in the microcomputer  17  inside the transmitter  1 , it is possible to associate suitable operations of a suitable human interface device with suitable control data for a camcorder or audio mixer. For example, for an audio mixer with a function that applies effects (special effects) to an audio signal, it is possible to associate suitable operations of a keyboard with control data for turning such effect function on and off. 
         [0143]    Also, in the description given above, a system that inputs an audio signal into a camcorder is shown in  FIG. 3 . However, the embodiment of the present invention may also be applied to remote operation (such as remote operation that starts or stops image pickup) of an image pickup apparatus in a system where an audio signal is inputted into an image pickup apparatus that does not have a function for recording images and audio. The embodiment of the present invention may also be applied to remote operation (such as remote operation that starts or stops recording) of a recording apparatus in a system where an audio signal is inputted into a recording apparatus (such as a VTR) that does not have an image pickup function but records images and audio or a dedicated audio recording apparatus. 
         [0144]    As described earlier,  FIG. 7  shows a system where a receiver and an audio mixer are connected by a cable. However, the embodiment of the present invention may be applied to a system where an audio signal is transferred from a transmitter into an audio mixer that has a receiver installed therein. 
         [0145]      FIG. 14  is a block diagram showing an example where the receiver  2  of the configuration shown in  FIG. 4  is installed in the audio mixer  5  of the configuration shown in  FIG. 9 . Parts that are the same as in  FIG. 4  and  FIG. 9  are assigned the same reference numerals. In this example, in place of the audio input terminal  51   a,  an audio signal from the D/A converter  22  is supplied to an amp  52   a.  In place of the communication terminal  58   a,  control data extracted by the unpacketizing circuit  21  is sent directly to the microcomputer  59 , with the microcomputer  59  controlling the variable volume control  56 , the variable volume control  53   a,  or the switch  54   a  in accordance with the control data. 
         [0146]    In the description above, the USB terminal  16  is provided in the transmitter  1 . However, a terminal other than a USB terminal that can connect a human interface device may be provided in the transmitter  1  and data corresponding to an operation of the human interface device connected to such terminal may be transmitted as radio waves from the transmitter  1 . 
         [0147]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.