Abstract:
An object of the present invention is to provide a multi-channel transmission system suitable for a digital broadcasting system that broadcasts television programs of many channels. Specifically, a selected one of television programs of a plurality of channels is supplied to an AV adjusting device. At this time, the selected television program is supplied to a monitor to allow recognition of its adjustment state. Since video signals and audio signals of television programs supplied from respective program supplying companies and program producing companies have different characteristics, they need to be adjusted to have common characteristics. Adjusted television programs and unselected television programs are supplied to a multiplexing section via routers.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a signal transmission system and method, a signal adjusting apparatus and method, and a routing apparatus that are used in multi-channel digital broadcasting systems. In particular, the invention relates to a system which efficiently adjusts and routes a video signal and/or an audio signal that is included in a multi-channel television program. 
     2. Description of the Related Art 
     At present, digital broadcasting systems are proposed in which video data or audio data is compressed and coded by using the MPEG2 (Moving Picture Experts Group Phase 2) and a resulting coded stream is broadcast by ground waves or satellite-relayed waves. Such digital broadcasting systems can transmit television programs of 100 or more channels simultaneously even by using an existing transmission bandwidth because a video signal and an audio signal of each channel are compressed by using the MPEG standard. 
     FIG. 1 shows an example configuration of a conventional 1-channel broadcasting system. A broadcast program schedule planning section  1  generates and registers in itself a program schedule table for management of the broadcast hours of program materials that are supplied from program suppliers. Further, the broadcast program schedule planning section  1  supplies proper control commands to a program material providing section  2  and a multiplexing section  3  so that television programs will be broadcast according to the generated program schedule table. 
     The program material providing section  2  performs switching and image processing such as special-effects processing on a video signal and an audio signal of a television program that is supplied from an editing studio or a news studio within a broadcasting station, and outputs, to the multiplexing section  3 , a program (a video signal and an audio signal) that is based on the program schedule table supplied from the broadcast program schedule planning section  1 . 
     Based on the program schedule table supplied from the broadcast program schedule planning section  1 , the multiplexing section  3  codes the video signal and the audio signal that are supplied from the program material providing section  2  according to the MPEG standard, and multiplexes encoded video and audio signals. 
     As described above, future digital broadcasting systems are required to transmit television programs of 100 or more channels. However, it is difficult for existing broadcasting stations to produce television programs of 100 or more channels by themselves. Therefore, it is a common practice that broadcasting stations are supplied with a plurality of program supplying companies or program producing companies. 
     In this case, since each program supplying company or program producing company produces television programs by using its own broadcasting equipment, the characteristics of a video signal and an audio signal that constitute a television program vary depending on the program supplying company or program producing company. The characteristics of a video signal mean its level, the gain value of its chroma component, the gain and hue offset values, etc. The characteristics of an audio signal mean the levels of the respective audio channels such as the levels of the first to fourth audio channels to which a plurality of languages (English, Japanese, and French) are assigned and the levels of the respective audio channels to which stereo sounds (right audio and left audio) are assigned, and other characteristics. 
     That is, a broadcasting station is supplied, from respective program supplying companies and program producing companies, with pairs of video signals and audio signals that have different characteristics. Therefore, if television programs that are supplied from the respective program supplying companies and program producing companies were broadcast to homes as they are, that is, without being modified, viewers would have a sense of incongruity when they change the channel of television programs. For example, if channels of television programs have a difference in video signal level, there occurs a problem that the brightness of a television picture varies when a viewer switches between those channels. There is another problem that the language of a sound that is output from a television receiver varies when a viewer switches the channel from one television program in which English is assigned to the first audio channel and Japanese is assigned to the second audio channel to another television program in which French is assigned to the first channel and English is assigned to the second audio channel. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a multi-channel transmission system suitable for a digital broadcasting system that broadcasts television programs of many channels. 
     Another object of the invention is to provide a signal adjusting apparatus that modifies television programs having different characteristics that are supplied from respective program supplying companies and program producing companies into ones having common characteristics. 
     A further object of the invention is to make it possible to adjust television programs of a plurality of channels easily in a short time in adjusting the signal characteristics of the respective television programs. 
     According to an aspect of the invention, there is provided a transmission system for transmitting television programs of a plurality of channels, comprising means for receiving a plurality of source television programs supplied from a plurality of program supply sources, respectively; routing means for selecting at least one of the plurality of source television programs, and for routing the selected source television program; means for adjusting a video signal and/or audio signal included in the selected television program so that the video signal and/or the audio signal of the selected source television program and video signals and/or audio signals of the other source television programs have common settings; and transmitting means for multiplexing an adjusted television program that is output from the adjusting means with the other television programs that are output from the routing means, and transmitting multiplexed television signals. 
     According to another aspect of the invention, there is provided a signal adjusting apparatus for adjusting video signals and/or audio signals constituting a plurality of television programs, comprising means for receiving a plurality of source television programs; routing means for routing the plurality of source television programs, and for selecting at least one of the plurality of source television programs; and means for adjusting a video signal and/or audio signal of the selected television program so that the video signal and/or the audio signal of the selected television program and video signals and/or audio signals of the other television programs have common characteristics. 
     According to a further aspect of the invention, there is provided a routing apparatus for routing a plurality of source television programs, comprising selecting means for selecting at least one of the plurality of source television programs; routing means for routing television programs; adjusting means for adjusting a characteristic of a video signals and/or an audio signals of a source television signal, and for outputting an adjusted television program; and control means for controlling the routing means so that the selected source television program is supplied to the adjusting means and that the adjusted television program and source television programs that were not selected by the selecting means are supplied to multiplexing means. 
     According to a still further aspect of the invention, there is provided a routing apparatus for routing a plurality of source television programs, comprising selecting means for selecting at least one of the plurality of source television programs; routing means for routing television programs; adjusting means for adjusting a characteristic of a video signals and/or an audio signals of a source television signal, and for outputting an adjusted television program; monitoring means for monitoring a video signal and/or an audio signal of the adjusted television program; and control means for controlling the routing means so that the selected television program is supplied to the adjusting means and that the adjusted television program that is output from the adjusting means is supplied to the monitoring means so that a result of an adjustment by the adjusting means of the video signal and/or the audio signal of the adjusted television program can be monitored on a real-time basis by the monitoring means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing an example configuration of a conventional broadcasting system; 
     FIG. 2 is a block diagram showing an example configuration of a digital broadcast system according to the present invention; 
     FIG. 3 is a block diagram showing an example configuration of a program material providing section  2  shown in FIG. 2; 
     FIG. 4 shows an example of a monitor selector CP  21 A- 1  shown in FIG. 3; 
     FIG. 5 shows an example of an AV remote controller CP  31 A- 1  shown in FIG. 3; 
     FIGS.  6 (A) and  6 (B) are tables showing adjustment items of a video signal; 
     FIGS.  7 (A) and  7 (B) are tables showing adjustment items of audio signals; 
     FIG. 8 is a table showing a display example in a display section D- 4 ; 
     FIG. 9 is a block diagram showing an example configuration of an AV remote controller  31 - 1  shown in FIG. 3; 
     FIG. 10 is a block diagram showing an example configuration of a portion of a display section  45  that corresponds to a setting button S- 4  of a manipulation section  44  shown in FIG. 9; 
     FIG. 11 is a circuit diagram showing an example configuration of a portion of the display section  45  that corresponds to an adjustment button C- 1  of the manipulation section  44  shown in FIG. 9; 
     FIG. 12 is a block diagram showing an example configuration of a PCNS control device  32  shown in FIG. 3; 
     FIG. 13 shows memory areas of a nonvolatile memory RAM  84  shown in FIG. 12; 
     FIG. 14 is a block diagram showing an example configuration of an AV adjusting device  33 - 1  shown in FIG. 3; 
     FIG. 15 is a flowchart showing an LED turning-on process; 
     FIG. 16 is a circuit diagram showing another example configuration of the portion of the display section  45  that corresponds to the adjustment button C- 1  of the manipulation section  44  shown in FIG. 9; and 
     FIG. 17 is a flowchart illustrating a process for prohibiting program adjustments. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 shows an example configuration of a digital broadcast system. A program schedule table for management of the broadcast hours of program materials etc. that are supplied from program suppliers is registered in a broadcast program schedule planning system  1 . According to the program schedule table, the broadcast schedule planning system  1  controls a customer management system  2  to a modulation circuit  11 . 
     The customer management system  2  manages information relating to customer management such as customer registration information and accounting information, and generates information to be supplied to a customer viewing permission system  3  such as information relating to the contracts with viewers and information relating to the setting of scrambling for disabling viewing of programs. 
     The customer viewing permission system  3  encodes information that is supplied from the customer management system  2  and generates packet data that will be multiplexed in a multiplexer system  9 . 
     An EPG system  4  generates data for introducing programs such as broadcast hours and program contents (hereinafter referred to as “EPG data”) and supplies it to the multiplexer system  9 . 
     A program material providing system  5  adjusts, when necessary, video signals and audio signals of programs that are supplied from program suppliers and outputs resulting signals to a server system  6 . 
     Constituted of disk drives that are connected together in array form, a control computer, etc., the server system  6  holds programs that are supplied from the program material providing system  5 . Further, the server system  6  generates programs of the respective channels according to the program schedule table of the broadcast program schedule planning system  1  and supplies those programs to a routing system  7 . 
     According to the program schedule table that is supplied from the broadcast program schedule planning system  1 , the routing system  7  performs routing so that a plurality of programs that are supplied from the server system  6  are output on proper channels. 
     Controlled by a control unit  10 , an encoding system  8  encodes, according to the MPEG 2  standard, for example, video signals and audio signals of programs that are supplied from the routing system  7 , and outputs resulting signals to the multiplexer system  9 . 
     The control unit  10  acquires, via a LAN  12 , packet data that are generated by the customer viewing permission system  3  and supplies those to the multiplexer system  9 . Controlled by the control unit  10 , the multiplexer system  9  multiplexes information that is supplied from the control unit  10  with EPG data that is supplied from the EPG system  4  and signals that are supplied from the encoding system  8  and outputs a resulting signal to the modulation circuit  11 . 
     The modulation circuit  11  modulates a multiplexed signal that is supplied from the multiplexer system  9  and transmits a resulting signal to a satellite (not shown). 
     FIG. 3 shows a specific configuration of the program material providing section  100 . In this example, there are two buses: a router bus  20  and a PCNS (processor control network system) bus  30 . N monitor selectors  21 - 1  to  21 -N, a video router  22 , an audio router  23 , a monitor selector control device  24 , and an output controller  25  are connected to the router bus  20 . N AV remote controllers  31 - 1  to  31 -N, a PCNS control device  32 , L AV adjusting devices  33 - 1  to  33 -L are connected to the PCNS bus  30 . 
     The monitor selector  21 - 1  generates a control signal to cause a monitor  26 - 1  to display video of the program of a channel that is selected by the user&#39;s manipulation of a monitor selector control panel (hereinafter abbreviated as “monitor selector CP”)  21 A- 1  and to cause a speaker  27 - 1  to output its sound, and outputs the control signal to the monitor selector control device  24  via the router bus  20 . As shown in FIG. 4, the monitor selector CP  21 A- 1  is composed of channel buttons M C  that are manipulated to select a channel, a lock button M L  for disabling use of the monitor selector CP  21 A- 1 , a protect button M T  for disabling adjustments for a selected channel, and an error display portion D E . 
     Further, connected to the AV remote controller  31 - 1  via a  9 P cable  10 - 1  with an RS- 422 C interface, the monitor selector  21 - 1  supplies the number of a selected channel to the AV remote controller  31 - 1 . 
     The monitor selectors  21 - 2  to  21 -N are configured in the same manner as the monitor selector  21 - 1  and hence will not be described. 
     The monitor selector control device  24  stores control signals that are output from the monitor selectors  21  in a built-in memory, and reads out the control signals and outputs those to the video router  22  and the audio router  23  via the router bus  20 . 
     Directly connected to the AV adjusting devices  33  and the monitors  26 , the video router  22  performs routing so that a video signal that is output from an AV adjusting device  33  corresponding to a channel specified by a control signal that is output from the monitor selector control device  24  is supplied to a similarly specified monitor  26 . This configuration allows the user to monitor video of the program of a selected channel. 
     Directly connected to the AV adjusting devices  33  and the speakers  27 , the audio router  23  performs routing so that an audio signal that is output from an AV adjusting device  33  corresponding to a channel specified by a control signal that is output from the monitor selector control device  24  is supplied to a specified speaker  27 . This configuration allows the user to monitor sound of the program of a selected channel. 
     The video signal and the audio signal that are output from the video router  22  and the audio router  23 , respectively, are also supplied to the multiplexing section  3 . This is controlled by the output controller  25  that is connected to the router bus  20 . 
     The AV remote controller  31 - 1  receives and stores a control signal (described later) that is transmitted from the PCNS control device  32  via the PCNS bus  30 . The AV remote controller  31 - 1  is supplied with a channel number from the remote controller  21 - 1  via the  9 P cable  10 - 1 . 
     When an adjustment condition (i.e., an adjustment item and its adjustment value) is set by the user&#39;s manipulation of the AV remote controller control panel (hereinafter abbreviated as “AV remote controller CP”)  31 A- 1 , the AV remote controller  31 - 1  compares the adjustment condition thus set with a stored adjustment condition that was set by a control signal that was supplied from the PCNS control device  32 . If they are different from each other, the AV remote controller  31 - 1  generates a control signal based on the channel number that was supplied from the monitor selector  21 - 1  and the thus-set adjustment condition and outputs it to the PCNS control device  32  via the PCNS bus  30 . 
     In this example, communication between the AV remote controller  31 - 1  and the PCNS control device  32  is performed by polling in which the AV remote controller  31 - 1  and the PCNS control device  32  are made a slave and a host, respectively. Therefore, the AV remote controller  31 - 1  outputs a generated control signal to the PCNS control device  32  after its transmission is permitted by the PCNS control device  32 . 
     FIG. 5 shows an example of the AV remote controller CP  31 A. In this example, the AV remote controller CP  31 A serves for adjustment of a video signal of a 1-channel program and audio signals of 4-channel programs. Four adjustment buttons C- 1  to C- 4  are selected in adjusting a video signal. The user sets an adjustment value by selecting any of those buttons and manipulating a volume dial T. 
     As shown in FIG.  6 (A), the user can adjust the gain of a video signal in a range of −20 to +20 IRE by selecting the adjustment button C- 1 . Similarly, the user can adjust the gain of a chroma signal in a range of −30% to +30% by selecting the adjustment button C- 2 , can adjust the offset in a range of −7.5 to +7.5 IRE by selecting the adjustment button C- 3 , and can adjust the hue in a range of −20 to +20 degrees by selecting the adjustment button C- 4 . Adjustment values of the respective items are displayed in a display section D- 1  in percent (−100% to +100%) or in hexadecimal form (00h to FFh). FIG.  6 (B) shows initial values of the gain of a video signal, the gain of a chroma signal, the offset, and the hue as well as percent display examples (000%) and hexadecimal display examples (80h) in the display section D- 1 . 
     Four adjustment buttons C- 5  to C- 8 , which are disposed on the right of the adjustment button C- 4 , are selected in adjusting the levels of audio signals. The user can adjust the levels of audio signals of programs of four channels CH 1 -CH 4  in a range of −6 to +6 dB as shown in rows “C-5” to “C-8” in FIG.  7 (A), respectively, by selecting any of those buttons and manipulating the volume dial T. Adjustment values of the respective items are displayed in a display section D- 2  in percent (−100% to +100%) or in hexadecimal form (00h to FFh). FIG.  7 (B) shows, in rows “C-5” to “C-8, ” initial values of the audio signal levels as well as percent display examples (000%) and hexadecimal display examples (80h) in the display section D- 2 . 
     Four adjustment buttons C- 9  to C- 12 , which are disposed on the right of the adjustment button C- 8 , are selected in adjusting the phases of audio signals. The user can adjust the positive phases of audio signals of programs as shown in rows “C-9” to “C-12” in FIG.  7 (A), respectively, by selecting any of those buttons and manipulating the volume dial T. 
     The user can also adjust the negative phases of audio signals of programs as shown in rows “R P -1” to “R P -4” in FIG.  7 (A), respectively, by manipulating a setting button S- 1 . In this case, the switching among the adjustment items is made by a toggle operation. Adjustment values of the respective items are displayed in a display section D- 3 . FIG.  7 (B) shows, in rows “C-9” to “C-12,” initial values of the phases of audio signals as well as percent display examples and hexadecimal display examples in the display section D- 3 . 
     An adjustment button C- 13  is selected in adjusting the delay of an audio signal. The user can adjust the delay in a range of 0 to 15 fields as shown in row “C-13” in FIG.  7 (A) by selecting the adjustment button C- 13  and manipulating the volume dial T. An adjustment value is displayed in a display section D- 4 . FIG.  7 (B) shows, in row “C-13,” an initial value of the delay of an audio signal as well as a percent display example and a hexadecimal display example in the display section D- 4 . 
     An adjustment button C- 14  is to display the status of a video signal of a selected program. When the adjustment button C- 14  is selected, for example, a display as shown in FIG. 8 is made in the display section D- 4  in accordance with the status of a video signal. FIG. 8 shows explanations of the contents of displays and hexadecimal data of the respective displays. 
     An adjustment button C- 15  is to display the status of an audio signal of a selected program. An adjustment button C- 16  is manipulated in setting all adjustment values at initial values. When the adjustment button C- 15  or C- 16  is manipulated, a display as shown in FIG. 8 is made in the display section D- 4 . FIG. 8 shows, in addition to the display examples in the display section D- 4 , the contents of displays and hexadecimal data of the respective displays. 
     The number of a selected channel is displayed in a display section D- 5 . 
     A setting button S- 2  is manipulated in setting an initial value for a selected adjustment item. A setting button S- 3  is selected to disable the use of this AV remote controller CP  31 A- 1 . A setting button S- 4  is selected to disable adjustments for a selected channel. 
     Since the AV remote controllers  31 - 2  to  31 -N have the same configuration as the AV remote controller  31 - 1 , they will not be described. 
     Returning to FIG. 3, the PCNS control device  32  inquires, on a regular basis, the AV remote controllers  31  of presence/absence of a transmission request. If a transmission request is present, the PCNS control device  32  gives transmission permission to the AV remote controller  31  concerned unless the PCNS control device  32  has another item to be processed hastily. As a result, the AV controller  31  transmits a control signal (adjustment condition). The PCNS control device  32  receives and stores it, and then outputs it to the PCNS bus  30 . 
     Programs (video signals and audio signals) supplied from program suppliers are input to the AV adjusting devices  33 . The AV adjusting devices  33  have a switch (not shown), such as a DIP switch, which enables setting of an address when manipulated. When a control signal that is transmitted from the PCNS control device  32  via the PCNS bus  30  is directed to the address set in such a manner, the AV adjusting device  33  acquires it. The Av adjusting device  33  performs adjustments on an input video signal and audio signal based on the acquired control signal and outputs a resulting video signal to the video router  22  and a resulting audio signal to the audio router  23 . 
     Next, the operations of the monitor selectors  21  to the speakers  27  will be described. When the user makes setting to monitor both video and sound of a program of a certain channel P by manipulating the channel button M C  on the monitor selector CP  21 A- 1  (see FIG. 4) of the monitor selector  21 - 1 , for example, the monitor selector  21 - 1  supplies the number of the thus-set channel P to the AV remote controller  31 - 1  via the  9 P cable  10 - 1  and generates a control signal for controlling the video router  22  and the audio router  23  and outputs it to the monitor selector control device  24  via the router bus  20 . 
     The monitor selector control device  24  stores the number of channel P that is supplied from the monitor selector  21 - 1  in the built-in memory, and reads it out and outputs it to the video router  22  and the audio router  23  via the router bus  20 . 
     The video router  22  performs routing so that a video signal that is output from an AV adjusting device  33 -i (i=1, 2, 3, . . . , L) that adjusts the program of channel P specified by a control signal that is supplied from the monitor selector control device  24  is supplied to the monitor  26 - 1 . The audio router  23  performs routing so that an audio signal that is output from the AV adjusting device  33 -i specified by the control signal is supplied to the speaker  27 - 1 . As a result, video of the program of channel P is displayed on the monitor  26 - 1  and sound of the program of channel P is output from the speaker  27 - 1 . 
     In this manner, the program of the selected channel P is monitored by the operations of the monitor selector  21  to the speaker  27 . 
     Next, the operations of the AV remote controllers  31  to the AV adjusting devices  33  will be described. First, example configurations of the AV remote controllers  31 , the PCNS control device  32 , and the AV adjusting devices  33  will be described. 
     FIG. 9 shows an example configuration of the AV remote controller  31 - 1 . A flash ROM  42  stores various programs to be executed by a CPU  41 , the ID of the AV remote controller  31 - 1 , and initial values of adjustment items (i.e., adjustment items that can be selected by the adjustment buttons C). A RAM  43  stores, when necessary, various data that are necessary when the CPU  41  executes various processes, and also stores a control signal that is supplied from the PCNS control device  32 . 
     A manipulation section  44  is composed of the setting buttons S- 1  to S- 4 , the adjustment buttons C- 1  to C- 16 , and the volume dial T of the AV controller CP  31 A- 1  shown in FIG.  5  and other parts. When any of those buttons etc. is manipulated by the user, the manipulation section  44  outputs a command corresponding to the manipulation to the CPU  41 . 
     A display section  45  has the display sections D- 1  to D- 5  of the AV remote controller CP  31 A- 1  shown in FIG.  5  and displays prescribed alphanumeric characters therein. Further, the display section  45  has a configuration shown in FIG. 10 that can cause the setting buttons S- 1  to S- 4  to output light and a configuration shown in FIG. 11 that can cause the adjustment buttons C- 1  to C- 16  to output light. 
     FIG. 10 shows an example configuration of a portion of the display section  45  that corresponds to the setting button S- 4  of the manipulation section  44 . A decoder  50  decodes a command that is supplied from the CPU  41  and outputs a resulting signal to a driver  51 . The driver  51  switches the output to be supplied to an LED  52  to H or L according to the signal from the decoder  50 . One terminal of the LED  52  is connected to a 5 V voltage source and the other terminal is connected to the driver  51 . The LED  52  emits light when the output of the driver  51  is L. For example, when the LED  52  emits light, the window W that is provided at the center of the setting button S- 4  of the AV remote controller CP  31 A- 1  shines. Checking whether the window W shines or not, the user can recognize whether the setting button S- 4  was manipulated properly or not. Portions of the display section  45  that correspond to the setting buttons S- 2  to S- 4  of the manipulation section  44  have the same configuration as the portion of the display section  45  that corresponds to the setting button S- 1 , they will not be illustrated nor described. 
     FIG. 11 shows an example configuration of a portion of the display section  45  that corresponds to the adjustment button C- 1  of the manipulation section  44 . The decoder  50  that is the same as in the portions of the display section  45  that correspond to the setting buttons S- 1  to S- 4  is connected to a driver  61 , and decodes a command that is supplied from the CPU  41  and outputs a resulting signal. The driver  61  is connected to the respective cathodes of an LED  62  that emits green light and an LED  63  that emits orange light. The respective anodes of the LEDs  62  and  63  are connected to a 5 V voltage source. 
     A latch  71  of the driver  61  is connected to the base of an NPN transistor  72 . The emitter of the transistor  72  is grounded. The collector of the transistor  72  is connected to the 5 V voltage source via a resistor  74  and to the cathode of the LED  62  via a resistor  75 . The base of an NPN transistor  73  is connected to the collector of the transistor  72 . The emitter of the transistor  73  is grounded, and its collector is connected to the cathode of the LED  63  via a resistor  76 . 
     Having an SIO (serial I/O interface), for example, a communication section  46  shown in FIG. 9 outputs or receives a signal via the PCNS bus  30  to which the SIO is connected. Further, having an RS-422C interface, the communication section  46  receives a channel number from, for example, the monitor selector  21 - 1  via the  9 P cable  10 - 1 - to which the RS-422C interface is connected. An interface  47 , which is provided between the CPU  41  and the manipulation section  44  to the communication section  46 , performs interface operations. 
     Since the AV remote controllers  31 - 2  to  31 -N have the same configuration as the AV remote controller  31 - 1 , they will not be illustrated nor described. 
     FIG. 12 shows an example configuration of the PCNS control device  32 . A CPU  81  executes various processes according to various programs that are stored in a flash ROM  82 . A RAM  83  stores, when necessary, various data that are necessary when the CPU  81  executes various processes. For example, as shown in FIG. 13, a nonvolatile RAM  84  is provided with memory areas corresponding to addresses that are set in the AV adjusting devices  33 - 1  to  33 -L. Adjustment conditions and setting conditions (described later) that are set in control signals supplied from the AV remote controllers  31  are stored in the corresponding memory areas. 
     An input section  85  is manipulated by the user when necessary in inputting a prescribed command to the CPU  81 . A display section  86  displays prescribed characters or an image. Having an SIO, for example, a communication section  87  outputs or receives a signal to or from the PCNS bus  30  to which the SIO is connected. An interface  88 , which is provided between the CPU  81  and the input section  85  to the communication section  87 , performs interface operations. 
     FIG. 14 shows an example configuration of the AV adjusting device  33 - 1 . Connected to the PCNS bus  30 , a bus interface  92  receives or outputs data via the PCNS bus  30 . An address setting section  93  is formed by a DIP switch, for example, and the address of the AV adjusting device  33 - 1  is set in the address setting section  93 . An AV adjusting section  94  performs necessary adjustments on a video signal or an audio signal that is input from a program supplier, and outputs a resulting video signal to the video router  22  or a resulting audio signal to the audio signal  23 . 
     A control section  91  controls the bus interface  92  to the AV adjusting section  94  and executes various processes. For example, when a control signal that is transmitted via the PCNS bus  30  is directed to the address that is set in the address setting section  93 , the control section  91  controls the bus interface  91  to have it receive the control signal. Further, the control section  91  extracts an adjustment condition from the received control signal and controls the AV adjusting section  94 . 
     The AV remote controllers  31 , the PCNS control device  32 , and the AD adjusting devices  33  are configured as described above. Next,-their operations will be described. 
     For example, if an adjustment condition is set as a result of selection of an adjustment button C of the AV remote controller CP  31 A- 1  and manipulation of the volume dial T in a state that the number of channel P that is output from the monitor selector  21 - 1  has been received via the  9 P cable  10 - 1  and is displayed in the display section D- 5  of the AV remote controller CP  31 A- 1 , the manipulation section  44  outputs the thus-set adjustment condition to the CPU  41 . If a setting button S of the AV remote controller CP  31 A- 1  is manipulated, the manipulation section  44  outputs a signal corresponding to the manipulation to the CPU  41 . 
     An operation of causing an adjustment button C or a setting button S to output light is performed when a channel number is supplied from a monitor selector  21  or the adjustment button C or the setting button S is manipulated. A procedure of this operation will be described later. 
     The CPU  41  of the AV remote controller  31 - 1  generates a control signal that includes the address of an AV adjusting device  33 -i corresponding to channel P, the ID of the AV remote controller  31 - 1  that is stored in the flash ROM  42 , and an adjustment condition (when it has been set through manipulation of an adjustment button C). When a setting button S is manipulated, the CPU  41  generates a control signal that includes a setting condition corresponding to the manipulated setting button S. In this example, the generated control signal is constituted of 10-byte data for adjustment of a video signal and 10-byte data for adjustment of an audio signal (20 bytes in total). The details of a control signal generation process to be executed when the setting button S- 4  is manipulated will be described later. 
     The CPU  41  of the AV remote controller  31 - 1  outputs the generated control signal to the PCNS control device  32  via the PCNS bus  30  after its transmission is permitted by the PCNS control device  32 . 
     The CPU  81  of the PCNS control device  32  controls the communication section  87  to have it receive the control signal that is transmitted from the AV remote controller  31 - 1 . Then, the CPU  81  extracts the adjustment condition, the setting condition, or the like from the control signal, and stores it in the memory area of the nonvolatile RAM  84  corresponding to the address of the AV adjusting device  33 -i that is set in the control signal. That is, when receiving the control signal from the AV remote controller  31 , the PCNS control device  32  immediately reads out the adjustment condition or the setting condition that has just been stored in the nonvolatile RAM  84 , generates a control signal by adding the address of the AV adjusting device  33 -i to it, and controls the communication section  87  to have it output the generated control signal to the PCNS bus  30 . 
     Further, the PCNS control device  32  reads out, at a constant cycle, an adjustment condition or a setting condition that is stored in the nonvolatile RAM  82 , generates a control signal by adding the address of the corresponding AV adjusting device  33 -i to it, and outputs the generated control signal to the PCNS bus  30 . 
     The control section  91  of the AD adjusting device  33 -i controls the bus interface  92  to have it receive the control signal that is transmitted via the PCNS bus  30  and directed to the AD adjusting device  33 -i. The control section  91  extracts the adjustment condition from the received control signal and supplies it to the AV adjusting section  94 . Based on the adjustment condition supplied from the control section  91 , the AV adjusting section  94  adjusts an input video signal or audio signal of a program of channel P and outputs a resulting signal. 
     Since the video signal that is output from the AV adjusting section  94  of the AV adjusting device  33 -i is routed by the video router  22  so as to be supplied to the monitor  26 - 1 , adjusted video of the program of channel P is displayed on the monitor  26 - 1 . Since the audio signal that is output from the AV adjusting section  94  of the AV adjusting device  33 -i is routed by the audio router  23  so as to be supplied to the speaker  27 - 1 , adjusted sound of the program of channel P is output from the speaker  27 - 1 . 
     The control signal (i.e., the control signal directed to the AV adjusting device  33 -i) that originates from the AV remote controller  31 - 1  and is output from the PCNS control device  32  to the PCNS bus  30  is received by not only the AV remote controller  31 - 1  but also the AV remote controllers  31 - 2  to  31 -N and stored in their respective RAMS  43 . Therefore, the AV remote controllers  31  can recognize adjustment conditions and setting conditions that are set for respective channels, which enables a process of prohibiting adjustment of the program of a prescribed channel (described later). 
     Next, an operation procedure of the AV remote controllers  31  in causing an adjustment button C to output light will be described with reference to a flowchart of FIG.  15 . For example, in the AV remote controller  31 - 1 , in a state that the number of a selected channel P is supplied from the monitor selector  21 - 1  and displayed in the display section D- 5  of the AV remote controller CP  31 A- 1 , at step SI the CPU  41  of the AV remote controller  31 - 1  judges whether an adjustment condition (an adjustment item and an adjustment value) has been set as a result of selection of an adjustment button C-i and manipulation of the volume button T. If an adjustment condition has been set, the process goes to step S 2 , where the adjustment value is extracted from the thus-set adjustment condition. 
     Then, at step S 3 , the CPU  41  reads out, from the flash ROM  42 , the initial value of the adjustment item of the adjustment condition that was judged “set” at step S 1 . At step S 4 , the CPU  41  judges whether the adjustment value that was extracted at step S 2  is equal to the initial value that was read out at step S 3 . If it is judged that the adjustment value is equal to the initial value, the process goes to step S 5 , where an operation of causing the adjustment button C-i to output green light is performed. 
     A portion (not shown) of the display section  45  corresponding to the adjustment button C-i has the same configuration as the portion of the display section  45  shown in FIG. 11 that corresponds to the adjustment button C- 1 . Therefore, in the following description, in the portion of the display section  45  corresponding to the adjustment button C-i, the elements corresponding to the elements of the portion of the display section  45  that corresponds to the adjustment button C- 1  are denoted by adding “-i” to the reference numerals of the latter, respectively. 
     Now, the operation of causing the adjustment button C-i to output green light will be described. The CPU  41  outputs a command for causing the LED  62 -i corresponding to the LED  62  shown in FIG. 11 to emit light to the decoder  50  of the display section  45  via the interface  47 . When receiving the command from the CPU  41 , the decoder  50  decodes it and outputs a resulting signal to the driver  61 -i. Based on the signal that is output from the decoder  50 , the output of the latch  71 -i of the driver  61 -i is turned to H. As a result, the transistor  72 -i is turned on, a current flows through the LED  62 -i, and the LED  62 -i emits light. At this time, since the base of the transistor  73 -i is at a low potential (i.e., grounded via the transistor  72 ), the transistor  73 -i is off. As a result, no current flows through the LED  63 -i and it does not emit light. 
     When the LED  62 -i emits light in this manner, the adjustment button C-i outputs green light. 
     If it is judged at step S 4  that the adjustment value is different from the initial value, the process goes to step S 6 , where an operation of causing the adjustment button C-i to output orange light is performed. 
     Now, the operation of causing the adjustment button C-i to output orange (amber) light will be described. The CPU  41  outputs a command for causing the LED  63 -i to emit light to the decoder  50  of the display section  45  via the interface  47 . When receiving the command from the CPU  41 , the decoder  50  decodes it and outputs a resulting signal to the driver  61 -i. Based on the signal that is output from the decoder  50 , the output of the latch  71 -i of the driver  61 -i is turned to L. As a result, the transistor  72 -i is turned off, whereupon a high voltage is applied to the base of the transistor  73 -i via the resistor  74  and the transistor  73 -i is turned on. As a result, a current flows through the LED  63 -i and the LED  63 -i emits light. At this time, since the transistor  72 -i is off, no current flows through the LED  62 -i and it does not emit light. P When the LED  63 -i emits light in this manner, the adjustment button C-i outputs orange (amber) light. 
     If it is judged at step S 1  that no adjustment condition has been set, the process goes to step S 7 , where the CPU  41  extracts, from a control signal that is stored in the RAM  43  and directed to one adjustment button C-i, an adjustment value that is set in the control signal. At step S 8 , the CPU  41  reads out the initial value of this adjustment item from the flash ROM  42 . 
     Then, at step S 9 , the CPU  41  judges whether the adjustment value that was extracted at step S 7  is equal to the initial value that was read out at step S 8 . If it is judged that the adjustment value is equal to the initial value, the process goes to step S 10 . If they are judged different from each other, the process goes to step S 11 . 
     At step S 10 , an operation of causing the adjustment button C-i to output green light is performed. At this step, the same operation as performed at step S 5  is performed. Therefore, this operation is not described here. At step S 11 , an operation of causing the adjustment button C-i to output orange (amber) light is performed. At this step, the same operation as performed at step S 6  is performed. Therefore, this operation is not described here. 
     After the execution of step S 10  or S 11 , the process goes to step S 12 , where the CPU  41  judges whether all adjustment buttons C- 1  to C- 16  are outputting green or orange light. If there remains adjustment buttons C that are not outputting light, the process returns to step S 7  to repeatedly execute the following steps for the portion of the display section  45  corresponding to the next adjustment button C-i (i=i+1) until all adjustment buttons C output light. 
     In this example, one of the LEDs  62  and  63  always emits light. 
     FIG. 16 shows another example of the driver  61 . In this example, to enable adjustment of the emission light intensity of the LEDs  62  and  63 , latches  101  and  102 , NPN transistors  103  and  104 , and resistors  105  and  106  are provided additionally. The latch  101  is connected to the base of the transistor  103 . The emitter of the transistor  103  is grounded and its collector is connected to the cathode of the LED  62  via the resistor  105 . The latch  102  is connected to the base of the transistor  104 . The emitter of the transistor  104  is grounded and its collector is connected to the cathode of the LED  63  via the resistor  106 . 
     For example, if the output of the latch  101  is turned to H and the transistor  103  is thereby turned on in a state that the LED  62  is emitting light (i.e., the output of the latch  71  is H and hence the transistor  72  is on), the current flowing through the LED  62  increases by a current that comes to flow to the transistor  103 . Therefore, the LED  62  comes to emit light that is stronger by an amount corresponding to the increased current. If the output of the latch  102  is turned to H and the transistor  104  is thereby turned on in a state that the LED  63  is emitting light (i.e., the output of the latch  71  is L and hence the transistor  72  is off and the transistor  73  is on), the current flowing through the LED  63  increases by a current that comes to flow to the transistor  103 . Therefore, the LED  63  comes to emit light that is stronger by an amount corresponding to the increased current. 
     The emission light intensity of the LEDs  62  and  63  can be adjusted in this manner. Therefore, for example, when an adjustment button C-i is manipulated (step S 1 ) in a state that all adjustment buttons C are outputting green or orange (amber) light (steps S 7  to S 12 ), the adjustment button C-i is caused to output stronger light (steps S 3  to S 6 ) so that the user can more easily recognize the selection of the adjustment button C-i. 
     Next, an operation procedure for prohibiting adjustment of the program of a prescribed channel will be described with reference to a flowchart of FIG.  17 . 
     For example, in a state that the number of channel P that is output from the monitor selector  21 - 1  is received via the  9 P cable  10 - 1  and displayed in the display section D- 5  of the AV remote controller CP  31 A- 1 , at step S 21  the CPU  41  of the AV remote controller  31 - 1  judges whether an adjustment condition has been set as a result of selection of an adjustment button C of the AV remote controller CP  31 A- 1  and manipulation of the volume button T. If no adjustment condition has been set, the process goes to step S 22 , where it is judged whether the setting button S- 4  has been manipulated. 
     If it is judged at step S 22  that the setting button S- 4  has not been manipulated, the process returns to step S 21 ; that is, the CPU  41  waits until an adjustment button C or the setting button S- 4  is manipulated. If it is judged at step S 22  that the setting button S- 4  has been manipulated, the process goes to step S 23 , where the CPU  41  generates a control signal that consists of the address of the AV adjusting device  33 -i corresponding to channel P, the ID of the remote controller  31 - 1  that is stored in the flash ROM  42 , and a setting condition that is a condition that control on the AV adjusting device  33 -i is prohibited (i.e., a control prohibition setting condition). When the setting button S- 4  of the AV remote controller CP  31 A- 1  is manipulated, its window W comes to output light. 
     Then, at step S 24 , the CPU  41  controls the communication section  46  to have it output the control signal to the PCNS control device  32  via the PCNS bus  30  after its transmission is permitted by the PCNS control device  32 . Then, the process is finished. 
     The control signal (i.e., the control signal directed to the AV adjusting device  33 -i) that was generated and output to the PCNS control device  32  in the above manner and in which the control prohibition setting condition for the AV adjusting device  33 -i is set is supplied from the PCNS control device  32  to all AV remote controllers  31 - 1  to  31 -N and stored there. 
     If it is judged at step S 21  that an adjustment condition has been set, the process goes to step S 25 , where the CPU  41  judges whether a control signal directed to the AV adjusting device  33 -i is stored in the RAM  43 . If it is stored, the process goes to step S 26 , where the CPU  41  judges whether a control prohibition setting condition is set in the control signal. 
     If it is judged at step S 26  that the control signal that is stored in the RAM  43  and directed to the AV adjusting device  33 -i includes a control prohibition setting condition, the process goes to step S 27 , where the CPU  41  judges whether its own ID (i.e., the ID of the AV remote controller  31 - 1 ) is set in the control signal. If its own ID is not set, the process is finished. That is, since no control signal for the AV adjusting device  33 -i is generated, the program of channel P is not adjusted. 
     If the CPU  41  judges at step S 25  that no control signal directed to the AV adjusting device  33 -i is stored in the RAM  43 , if the CPU  41  judges at step S 26  that the control signal stored in the RAM  43  and directed to the AV adjusting device  33 -i does not include control prohibition information, or if the CPU  41  judges at step S 27  that its own ID is set in the control signal stored in the RAM  43  and directed to the AV adjusting device  33 -i, the process goes to step S 28 , where the CPU  41  generates a control signal that consists of the address of the AV adjusting device  33 -i and the adjustment condition. That is, no control prohibition setting condition is set in the control signal generated at step S 28 . 
     At step S 29 , the CPU  41  controls the communication section  46  to have it output the control signal that was generated at step S 28  to the PCNS control device  32  via the PCNS bus  30  after its transmission is permitted by the PCNS control device  32 . Then, the process is finished. 
     As described above, a control signal for prohibiting adjustments for a selected channel can be generated by manipulating the setting button S- 4  of the AV remote controller CP  31 A- 1  (steps S 22  and S 23 ). Since a control signal in which a new adjustment condition is set is no longer generated for the AV adjusting device  33  corresponding to the controlprohibited channel (steps S 25 -S 27 ), the program of the selected channel is not adjusted. That is, for example, if a user manipulates the setting button S- 4  after adjusting the program of channel P by setting an adjustment condition by manipulating the AV remote controller CP  31 A- 1  of the AV remote controller  31 - 1  (steps S 28  and S 29 ), another user&#39;s altering the adjustment conditions that have been set for channel P by manipulating the AV remote controller CP of another AV remote controller  312  to  31 -N is prohibited. 
     In a state that adjustments for channel P are prohibited as a result of the user&#39;s manipulating the setting button S- 4  of the AV remote controller CP  31 A- 1  of the AV remote controller  31 - 1 , the setting of prohibition of adjustments for channel P can be cancelled by again manipulating the setting button S- 4  of the AV remote controller CP  31 A- 1 . 
     In the above configuration, video signals and audio signals are input to each AV adjusting device  33  via 150 lines. 
     As described above, an AV remote controller  31  directly acquires the number of a selected channel from a monitor selector  21  and generates a control signal based on the channel number, and the PCNS control device  32  supplies the control signal to an AV adjusting device  33  via the PCNS bus  30 . Therefore, a new AV adjusting device  33  or AV remote controller  31  can be added easily. For example, a new AV adjusting device  33  can be added by setting an address by manipulating a switch and connecting it to the PCNS bus  30 . 
     Since the above configuration eliminates the need for connecting the AV adjusting devices  33  to the AV remote controllers  31  via  9 P cables, the apparatus can be made less expensive and the entire system can be reduced in size. 
     Thirty-two monitor selectors  21  and  32  AV remote controllers  31  can be provided (i.e., N=32). In this case, a total of 1,600 AV adjusting devices  33  can be provided. 
     In the above embodiment, the two buses, that is, the router bus  20  and the PCNS bus  30 , are provided. For example, if the total number of AV adjusting devices  33  is smaller than 250, the two buses can be combined into a single bus.