Abstract:
An information receiver comprising a unit receiving information having a package number identifying the information, a first storage section where said package number is stored, a second storage section where reception information indicating whether or not said information associated with said package number was received, and a third storage section where display information indicating whether or not said information associated with said package number was displayed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a method of information transmission between an information transmitter and an information receiver. It also relates to the information transmitter and the information receiver.  
           [0002]    Conventionally, when information is broadcast from an information transmitter to an information receiver, the information receiver records whether or not the information has been received. In this recording method, the date and time the information was received and the number of channel through which data was transmitted are recorded.  
           [0003]    This method assumes that the received information is television programs, that is, video and sounds played back in real time, and that the received information is displayed at the same time it is received. However, the received information is sometimes recorded on such devices as a video cassette recorder but will not actually be played back. In addition, when multiple pieces of information are received in a specific period of time concurrently, only one of them is sometimes displayed and others are not.  
           [0004]    Another type of received information is data, that is, text or still images. Unlike TV program video, these are independent of the time for the TV program, in other words, the TV broadcasting time. That is, a TV program is usually broadcast in a specific period of time through a specific channel according to the TV program, while data may be broadcast multiple times a day or across multiple channels. In this case, the conventional method in which the date/time and the number of channel are recorded does not determine which data was received.  
           [0005]    Data, one type of received information, is also easy to record on a storage unit, meaning that there is also the problem that data was received but not was displayed and, as a result, the program rating cannot be determined.  
           [0006]    Another problem is that, when the audience received but did not displayed data, there is no device to estimate the reason for it.  
           [0007]    The conventional method by which the reception date/time and the number of channel used for reception are recorded does not indicate whether or not the audience actually displayed the received information.  
           [0008]    In particular, when the received information is data, the method does not indicate which data was received.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide a device and a method indicating which information was received and whether or not the received information was displayed when information is sent from sending equipment to receiving equipment.  
           [0010]    It is another object of the present invention to provide a device indicating, when the audience received but not displayed data, the reason for it.  
           [0011]    To achieve the above objects, the present invention attaches an identification number, called a package number, to transmission information. A receiver manages reception and display separately with package numbers as the key, and records the reception time and the display time so that data received but not displayed can be identified. The present invention also adds a content code representing the contents of received information to received information, and a display code representing a display priority to transmission data. This makes it possible, when the audience received but not displayed data, to estimate the reason for it.  
           [0012]    A system according to the present invention has a configuration described below. An information transmitter transmitting information comprises a unit creating a package number identifying the transmission information, a unit adding the package number to the transmission information, and a unit transmitting the transmission information having the package number to an information receiver.  
           [0013]    The information receiver comprises a unit receiving the transmission information having the package number identifying the transmission information and a unit determining, with the use of the package number, if the received transmission information was displayed on a display unit.  
           [0014]    The unit determining if the received transmission information was displayed, which is included in the information receiver, may determine if the received transmission information was displayed on the display unit based on a reception time at which the transmission information was received and a display time at which the transmission information was displayed.  
           [0015]    The information receiver has a first storage unit where the fact that the transmission information was received and the package number are stored and a second storage unit where, when the transmission information was displayed, the fact that the transmission information was displayed and the package number are stored. The unit determining if the received transmission information was displayed may determine whether the information was displayed, based on the contents stored in the first and second storage units.  
           [0016]    The information receiver may further comprise a unit adding a content code indicating the contents of the transmission information received by the unit receiving the transmission information and a display code indicating the display priority of the transmission information.  
           [0017]    The present invention also provides a method for use in the information receiver where information indicating whether or not the transmission information is to be displayed is stored, the information receiver receiving the transmission information from the information transmitter transmitting the information. The method comprises the steps of receiving the transmission information having the package number added by the information transmitter and identifying the transmission information, storing the fact that the transmission information was received and the package number added to the received transmission information, storing, when the received transmission information was displayed on the display unit of the information receiver, the fact that the transmission information was displayed and the package number added to the displayed transmission information, and determining whether or not the transmission information was displayed based on the stored package number.  
           [0018]    According to the present invention, when information is transmitted from transmission equipment to reception equipment, it is possible to determine which information was received and whether received information was displayed.  
           [0019]    The present invention also provides materials for use in estimating, when audience received but did not display data, the reason for it. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a diagram showing an example of the configuration of the system of a first embodiment.  
         [0021]    [0021]FIG. 2 is a diagram showing an example of the functional configuration of a data transmitter.  
         [0022]    [0022]FIG. 3 is a diagram showing an example of the hardware configuration of the data transmitter.  
         [0023]    [0023]FIG. 4 is a flowchart showing an example of main processing of the data transmitter.  
         [0024]    [0024]FIG. 5 is a diagram showing an example of the configuration of the management menu screen displayed on the data transmitter.  
         [0025]    [0025]FIG. 6 is a diagram showing an example of the configuration of the content code management table of the data transmitter.  
         [0026]    [0026]FIG. 7 is a diagram showing an example of the configuration of the data file of the data transmitter.  
         [0027]    [0027]FIG. 8 is a diagram showing an example of the configuration of the content code definition screen used by the content code definition function of the data transmitter.  
         [0028]    [0028]FIG. 9 is a diagram showing an example of the configuration of the package management table of the data transmitter.  
         [0029]    [0029]FIG. 10 is a diagram showing an example of the configuration of the packet management table of the data transmitter.  
         [0030]    [0030]FIG. 11 is a diagram showing an example of the format of a data packet.  
         [0031]    [0031]FIG. 12 is a diagram showing an example of the configuration of the table indicating the correspondence between the channel number and the packet ID.  
         [0032]    [0032]FIG. 13 is a diagram showing an example of the functional configuration of the data receiver.  
         [0033]    [0033]FIG. 14 is a diagram showing an example of the hardware configuration of the data receiver.  
         [0034]    [0034]FIG. 15 is a flowchart showing an example of main processing of the data receiver.  
         [0035]    [0035]FIG. 16 is a diagram showing an example of the configuration of the user attribute definition screen displayed on the data receiver.  
         [0036]    [0036]FIG. 17 is a diagram showing an example of the configuration of the content code management table of the data receiver.  
         [0037]    [0037]FIG. 18 is a diagram showing an example of the configuration of the channel management table of the data receiver.  
         [0038]    [0038]FIG. 19 is a diagram showing an example of the configuration of the execution management table of the data receiver.  
         [0039]    [0039]FIG. 20 is a diagram showing the relation between the provider display code and the audience display code.  
         [0040]    [0040]FIG. 21 is a diagram showing an example of the format of a program rating data packet. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0041]    An embodiment of the present invention will be described below.  
         [0042]    [0042]FIG. 1 is a diagram showing the configuration of the embodiment according to the present invention.  
         [0043]    This system comprises at least one data transmitter  10 , at least one data receiver  20 - 1 , . . . ,  20 -n, a communication satellite  1  acting as a medium through which these devices communicate, at least one total calculator  30  calculating data received from the data receivers, and a network  2  which is a medium via which the total calculator  30  communicates with the data receivers  20 - 1 , . . . ,  20 -n, and the data transmitters  10 . The communication media may be via radio waves or cable. It should be noted that the communication medium between the data receivers  20  and the total calculator  30  and between the data receivers  20  and the total calculator  30  may be the same or different.  
         [0044]    [0044]FIG. 2 shows the detailed functional configuration of the data transmitter  10 . The data transmitter  10  has five basic functions, that is, a packet transmission function  101 , a package management function  102 , a data management function  103 , a content code management function  104 , and an input/output management function  105 , and four tables, that is, a packet management table  107 , a package management table  108 , a data file  109 , and content code management table  110 . The packet transmission function  101  sends packets to the communication satellite  1 , which acts as a transmission medium, via a broadcasting transmitter  111 . The input/output management function  105  manages input/output to or from an input/output device  112  such as a display, keyboard, disk, and communication device.  
         [0045]    [0045]FIG. 3 shows the detailed hardware configuration of the data transmitter  10 . The data transmitter  10  comprises a CPU bus  121 , an expansion bus  122 , a bridge  123 , a CPU (central processing unit)  124 , a cache memory  125 , a memory  126 , an interrupt controller  127 , a broadcasting transmission controller  128 , a communication controller  129 , a disk controller  130 , an audio controller  131 , an input controller  132 , and a screen controller  133 . The cache memory  125  and the memory  126  each contain a controller, and the memory  126  contains a ROM and a RAM.  
         [0046]    The CPU bus  121  is a bus connecting to the CPU (central processing unit)  124 . The bridge  123 , CPU  124  cache memory  125 , memory  126 , and interrupt controller  127  are connected to the CPU bus  121 .  
         [0047]    The CPU  124  interprets instructions and controls execution, and the memory  126  stores programs and data. The cache memory  125  allows for high-speed access. The interrupt controller  127  controls an interrupt signal to the CPU, that is, a signal which suspends the current CPU processing temporarily and makes its own interrupt processing request. The bridge  123  is a circuit connecting the CPU bus  121  to the expansion bus  122 .  
         [0048]    The expansion bus  122  is a bus via which data is transferred to or from various input/output devices. To the expansion bus  122  is connected the broadcasting transmission controller  128 , communication controller  129 , disk controller  130 , audio controller  131 , input controller  132 , and screen controller  133 . The broadcasting transmission controller  128 , which controls broadcasting transmission via the communication satellite  1 , is connected to a broadcasting transmission device  134  which sends broadcasting waves to the communication satellite  1 . The communication controller  129  controls communication with other devices (other data receivers  20  or data transmitters  10 ) via a communication device  135  such as a modem or an ISDN terminal adapter over the network  2  such as a public network or ISDN network. The disk controller  130  is a controller such as an SCSI disk controller. It is connected to a package disk unit  136 , such as a CD-ROM drive or a DVD (Digital Video Disk) drive on which a package disk  3 , a removable recording medium, is mounted, and to a hard disk drive  137 . The audio controller  131 , which controls audio input and output, is connected to an audio input/output device  138  such as an microphone and speaker. The input controller  132  controls an input device  139  such as a keyboard or a mouse. The screen controller  133  controls a screen display device  140  such as a CRT, LCD, or PDP.  
         [0049]    The relation between the functional configuration shown in FIG. 2 and the hardware configuration shown in FIG. 3 will be described. All functions shown in FIG. 2 are achieved by the CPU  124  which interprets and executes programs implementing each function. When a function is executed, the corresponding program is in the memory  126  or cache memory  125 . At execution time, all tables and files shown in FIG. 2 are also in the memory  126  or cache memory  125 . At non-execution time, the programs, tables and files for the functions are in the memory  126  or on the hard disk drive  137 .  
         [0050]    The packet transmission function  101 , interpreted by the CPU  124 , issues instructions controlling the broadcasting transmitter  111  to the broadcasting transmission controller  128 . The input/output management function  105 , interpreted by the CPU  124 , controls input/output devices  120  such as the communication device  135 , package disk unit  136 , hard disk drive  137 , audio input/output device  138 , input device  139 , and screen display device  140  via the communication controller  129 , disk controller  130 , audio controller  131 , input controller  132 , and screen controller  133 .  
         [0051]    The functional operation of the data transmitter  10  will be described with reference to the drawings.  
         [0052]    [0052]FIG. 4 is a flowchart showing the main flow executed by the CPU  124  of the data transmitter  10 .  
         [0053]    The input/output management function  105  of the data transmitter  10  first displays a management menu on the screen display device  140  ( 1001 ) and enters the event-wait status ( 1002 ). The event-wait status refers to a status in which the function waits for an event, such as a click on a button or the reception of a packet, to occur.  
         [0054]    [0054]FIG. 5 shows an example of the management menu described above. A management menu  113  contains a content code management button  1131 , a data management button  1132 , a transmission management button  1133 , an end button  1134 , and a help button  1135 . Clicking the data management button  1132  with the use of the input device  139  causes a content code management event. Similarly, clicking the data management button  1132  causes a data management event, clicking the transmission management button  1133  causes a package management event, and clicking the end button  1134  causes an end event. Clicking the help button  1135  displays a brief description of each button.  
         [0055]    The following describes the operation that will be performed when an event is caused by clicking a button. (1) Referring to FIGS. 4 and 6, the following describes the operation that will be performed when a content code management event is caused by clicking the content code management button  1131  in the management menu  113 .  
         [0056]    The input/output management function  105  of the data transmitter  10  checks the type of event ( 1003 ) and calls the content code management function  104  because the event is a content code management event ( 1004 ).  
         [0057]    The content code management function  104  first displays the content code definition screen to prompt the user (transmission manager) to enter a content code definition. Based on this input, data is written into the content code management table  110 . When the user ends the content code definition, the content code management function ends.  
         [0058]    [0058]FIG. 6 shows an example of the structure of the content code management table  110 . This table has two fields: content code  1101  and definition  1102 . The content code  1101  is a code indicating the contents of data such as “the data is for men in their thirties”, “the data is for people living in Tokyo”, or “the data is for sports fans”. (2) Referring to FIGS. 4 and 7, the following describes the operation that will be performed when a data management event is caused by clicking the data management button  1132  in the management menu  113 .  
         [0059]    The input/output management function  105  of the data transmitter  10  checks the type of event ( 1003 ) and calls the data management function  103  because the event is a data management event ( 1005 ).  
         [0060]    The data management function  103  first displays the data definition screen to prompt the user (transmission manager) to enter a data definition. Based on this input, data is written into the data file  109 . When the user ends the data definition, the data management function ends.  
         [0061]    [0061]FIG. 7 shows an example of the structure of the data file  109 . The data file  109  has five fields: a data number  1091 , a data name  1092 , a data file name  1093 , a content code  1094 , and a provider display code  1095 . The user (transmission manager) defines these five items. The data number  1091 , used to identify data, is usually a number consisting of the code of data owner (owner company) and the number of data. The data name  1092  is the generic name of data. The data file name  1093  indicates the data itself. Sometimes, the data itself is a hybrid type file, for example, a hyper text file, composed of a plurality of files. Simple data is such data as text file data. The data file name  1093  usually contains storage location information such as a directory name. The content code  1094  is the content code of the data.  
         [0062]    The provider display code  1095  represents the provider&#39;s intention regarding the display priority. The provider display code  1095  indicates a criterion on which whether to display data is determined when data is received by the receiver. One of “display”, “non-display”, and “forced display” is selected. Whether or not data is actually displayed is decided by the relation with an audience display code previously set by the audience in the receiver. This relation will be described later. (3) Referring to FIGS. 4 and 8, and  9 , the following describes the operation that will be performed when a package management event is caused by clicking the transmission management button  1133  in the management menu  113 .  
         [0063]    The input/output management function  105  of the data transmitter  10  checks the type of event ( 1003 ) and calls the package management function  102  because the event is a package management event ( 1006 ).  
         [0064]    The package management function  102  first displays the transmission definition screen to prompt the user (transmission manager) to enter a transmission definition. FIG. 8 shows the transmission definition screen  114 . First, a data number  1142  of data (or product data) to be transmitted is selected. When the data number is selected, a corresponding data name  1141  is displayed. Next, a provider number  1144  of the provider providing the data is entered. The provider refers to a broadcasting company or a common carrier. When the provider number  1144  is entered, a provider name  1143  is displayed. Next, a channel number  1146  provided by the specified provider is entered. The channel number  1146  must be specified for each provider number. Data is sent to the specified channel. When the channel number is selected, a corresponding channel name  1145  is displayed. Next, a program number  1148  of a program of the channel is entered. The channel is divided into programs by broadcasting time. Data is sent to the specified program. When selected, a corresponding program name  1147  is displayed.  
         [0065]    When the user has filled out the above fields, a spot number is calculated. The spot number is the serial number of transmission. It is managed by the package management table  108 . FIG. 9 shows an example of the package management table  108 . The package management table  108  is composed of a provider number  1081 , a channel number  1082 , a program number  1083 , and a current spot number  1084 . The current spot number is an identification number assigned to transmitted data. The spot number is assigned to the combination of the provider number  1081 , channel number  1082 , and program number  1083 . When a new transmission specification is entered on the transmission definition screen  114 , the current spot number corresponding to the provider number  1081 , channel number  1082 , and program number  1083  is incremented by 1 and is displayed in the spot number  1149 , shown in FIG. 8, as a new spot number.  
         [0066]    The combination of the provider number  1144 , channel number  1146 , program number  1148 , and spot number  1149  is called a package number.  
         [0067]    Note that the channel number  1146  and the program number  1148  may be left unspecified. When they are not specified, the value of 0 is specified. When only the program number  1148  is left unspecified, it means that the transmission data does not depend on the program. This is useful when transmitting data to the different programs in the same channel several times repeatedly. When both the channel number  1146  and the program number  1148  are left unspecified, it means that the transmission data does not depend on the channel. This is useful when transmitting data across different channels several times repeatedly.  
         [0068]    Next, a transmission time  1150  is specified. The data is transmitted at the specified time. It is possible to specify the transmission time of “0” to transmit data immediately. When the program number is specified, the range of the specified transmission time that may be specified is limited.  
         [0069]    When the data number  1142  is specified, a content code  1152  and a display code  1153  corresponding to the data specified for the data management function are displayed on the transmission definition screen  114 . To change these settings only for the current transmission, the content code  1152  and/or display code  1153  may be specified. If they are not specified, the values in the data file  109  are set as the “default”.  
         [0070]    When all above values are entered, the user clicks a complete button  1155 . When the complete button  1155  is pressed, the package management function  102  writes information necessary for packet transmission into the packet management table  107  via the packet transmission function  101 .  
         [0071]    [0071]FIG. 10 shows the structure of the packet management table  107 . The packet management table  107  is composed of a package number  1071 , a data number  1072 , a transmission start time  1073 , a content code  1074 , and a provider display code  1075 . The package number  1071  is composed of the provider number  1144 , channel number  1146 , program number  1148 , and spot number  1149 . When there is a one-to-one correspondence between the provider number and the channel number, one of them need be specified. The values specified on the transmission definition screen  114  are assigned to these items.  
         [0072]    The packet transmission function  101 , which manages the packet management table  107 , sends data at the specified transmission time. Each time a record, or a row, is added to the packet management table  107 , the record is sent from the transmission station to the total calculator.  
         [0073]    [0073]FIG. 11 shows an example of the format of a transmission packet. A transmission packet  116  is composed of a packet ID  1161 , a package number  1162 , a content code  1163 , a display code  1164 , a data number  1165 , and data  1166 . These are created based on the packet management table  107 . The package number  1162  is composed of a provider number  11621 , a channel number  11622 , a program number  11623 , and a spot number  11624 . For each channel, the same value is assigned to the packet ID  1161  which is the predetermined ID of a transmission packet. That is, as shown in FIG. 12, the transmission equipment has a packet ID table  117 , the table containing the correspondence between a channel number  1171  and a packet ID  1172 .  
         [0074]    Next, the data receiver will be described.  
         [0075]    [0075]FIG. 13 shows the detailed functional configuration of the data receiver  20 . The data receiver  20  has five basic functions, that is, a packet selection reception function  201 , a channel management function  202 , a content code management function  203 , a data execution function  204 , and an input/output management function  205 , and three tables, that is, an execution management file  206 , a channel management table  207 , and a content code management table  208 . The packet selection reception function  201  receives packets from the communication satellite  1 , which is a transmission medium, via a broadcasting receiver  234 . The input/output management function  205  manages input/output to or from an input/output device  220  such as a display, keyboard, disk, and communication device.  
         [0076]    [0076]FIG. 14 shows the detailed hardware configuration of the data receiver  20 . The data receiver  20  comprises a CPU bus  221 , an expansion bus  222 , a bridge  223 , a CPU (central processing unit)  224 , a cache memory  225 , a memory  226 , an interrupt controller  227 , a broadcasting reception controller  228 , a communication controller  229 , a disk controller  230 , an audio controller  231 , an input controller  232 , and a screen controller  233 . The cache memory  225  and the memory  226  each contain a controller, and the memory  226  contains a ROM and a RAM.  
         [0077]    The CPU bus  221  is a bus connecting to the CPU (central processing unit)  224 . The bridge  223 , CPU  224  cache memory  225 , memory  226 , and interrupt controller  227  are connected to the CPU bus  221 .  
         [0078]    The CPU  224  interprets instructions and controls execution, and the memory  226  stores programs and data. The cache memory  225  is a unit executing high-speed access. The interrupt controller  227  controls an interrupt signal to the CPU, that is, a signal which suspends the current CPU processing temporarily and makes its own interrupt processing request. The bridge  223  is a circuit connecting the CPU bus  221  to the expansion bus  222 .  
         [0079]    The expansion bus  222  is a bus via which data is transferred to or from various input/output devices. To the expansion bus  222  is connected the broadcasting reception controller  228 , communication controller  229 , disk controller  230 , audio controller  231 , input controller  232 , and screen controller  233 . The broadcasting reception controller  228 , which controls broadcasting transmission via the communication satellite  1 , is connected to a broadcasting receiver  234  which receives broadcasting waves from the communication satellite  1 . The communication controller  229  controls communication with other devices (other data receivers  20  or data transmitters  10 ) via a communication device  235 , such as a modem or an ISDN terminal adapter, over the network  2  such as a public network or an ISDN network. The disk controller  230  is a controller such as an SCSI disk controller. It is connected to a package disk unit  236 , such as a CD-ROM drive or a DVD (Digital Video Disk) drive on which a package disk  3 , a removable recording medium, is mounted, to a hard disk drive  237 , and to an IC card device  238 . The audio controller  231 , which controls audio input and output, is connected to an audio input/output device  239  such as an microphone and speaker. The input controller  232  controls an input device  240  such as a keyboard or a mouse. The screen controller  233  controls a screen display device  241  such as a CRT, LCD, or PDP.  
         [0080]    The relation between the functional configuration shown in FIG. 13 and the hardware configuration shown in FIG. 14 will be described. All functions shown in FIG. 13 are achieved by the CPU  224  which interprets and executes programs implementing each function. When a function is executed, the corresponding program is in the memory  226  or cache memory  225 . At execution time, all tables and files shown in FIG. 13 are also in the memory  226  or cache memory  225 . At non-execution time, the programs for implementing the functions, tables, and files are in the memory  226 , the hard disk drive  237 , or IC card device  238 .  
         [0081]    The packet reception function  201 , interpreted by the CPU  224 , issues instructions controlling the broadcasting receiver  234  to the broadcasting reception controller  228 . The input/output management function  205 , interpreted by the CPU  224 , controls input/output devices  220  such as the communication device  235 , package disk unit  236 , hard disk drive  237 , IC card device  238 , audio input/output device  239 , input device  240 , and screen display device  241  via the communication controller  229 , disk controller  230 , audio controller  231 , input controller  232 , and screen controller  233 .  
         [0082]    The functional operation of the data receiver  20  will be described with reference to the drawings.  
         [0083]    [0083]FIG. 15 is a flowchart showing the main flow executed by the CPU  224  of the data receiver  20 .  
         [0084]    The data receiver  20  enters an event-wait status ( 2001 ).  
         [0085]    Assume that an audience information addition request is sent to the input/output management function  205  via the input/output device  220 . The input/output management function  205  causes a content code management event. When an event occurs, a check is made for the type of event ( 2002 ) and, if the event is a content code management event, a call is made to the content code management function  203  ( 2011 ).  
         [0086]    The content code management function  203  displays a user attribute definition screen  214  such as the one shown in FIG. 16. The screen is composed of a user name  2141 , a user ID  2142 , an attribute item  2143 , an attribute value  2144 , and a set flag  2145 . The set flag  2145  indicates whether or not the user has set an attribute item. On this screen, the user (audience) types, for example, “Machida 1-1, Machida-shi, Tokyo” into the attribute item “Address” in up to 80 alphanumeric characters which are allowed for the attribute value, or select  0  or a positive integer, which is allowed for the attribute value, into the attribute item “Age”. At this time, the user may reject to specify a final setting. To do so, the user may select and specify the “Reject reply” item. The user may also click the cancel button and does not enter values, for example, because the user is busy.  
         [0087]    A content code management table  208  is set up based on these inputs from the user (audience). FIG. 17 shows the structure of the content code management table  208 . Initially, the content code management table  208  of the data receiver  20  contains a content code  2081  and its definition  2082 . These values are preset values set up when the receiver was shipped. They may be updated when data is received. At input time, the attribute value specified by the user (audience) is compared with the definition  2082  and whether the value is specified or not is set in a status  2083 . The initial value of the status  2083  is set to “not specified”.  
         [0088]    Now, assume that the data receiver  20  has received a packet from the broadcasting receiver  234  and that an event has occurred. When an event occurs, the data receiver  20  checks the type of the event ( 2002 ). When a packet is received, the reception of the packet is considered as a packet reception event and the packet selection reception function  201  is called ( 2003 ). The packet selection reception function  201  selectively receives packets.  
         [0089]    First, at packet reception time, the data receiver inquires of the channel management function  202  about the packet ID of the received packet to determine whether the packet can be received. The channel management function  202  manages the channel management table  207 . FIG. 18 shows an example of the channel management table. The channel management table  207  is composed of a channel number  2071 , a packet ID  2072 , a contract status  2073 , and a reception status  2074 . The channel number  2071  and the packet ID  2072  are the same as those of the transmitter described above. The contract status  2073  represents whether the audience of the receiver has made the reception contract of the channel. The reception status indicates whether or not the audience of the receiver currently desires the reception through that channel. Even if the channel reception contract is made, the audience may not currently desire the reception through that channel for some reason other. For example, for a receiver capable of receiving only two channels at a time, the audience can receive through only two channels even if he or she has four contracted channels.  
         [0090]    If the inquiry result indicates a non-reception status, the packet is discarded ( 2006 ). If the result is a reception status, control goes to the next step.  
         [0091]    Next, the data receiver references the above-described content code management table  208  ( 2004 ), and checks if the content code added to the received packet is registered in the content code management table  208  ( 2005 ). If it is not registered, the packet is discarded ( 2006 ); if it is registered, the packet is received ( 2007 ).  
         [0092]    Next, the data receiver  20  checks if data may be displayed ( 2008 ). The audience specifies, in advance, an audience display code indicating the audience&#39;s intention about the display priority. One of “all display”, “no specification”, and “all non-display” may be specified. The default is “no specification”. FIG. 20 shows the relation between this audience display code and the provider display code in a packet. When the audience specifies “all display”, all data that may be received is displayed regardless of the provider&#39;s specification. When the audience specifies “no specification”, data is not displayed only when the provider specifies “non-display”. In this case, “no-display” means that “data is not displayed automatically”; it is possible for the audience to specify and display data stored in the storage unit. When the audience specifies “all non-display”, all data that may be received is not displayed regardless of the provider&#39;s specification. The audience may change this display specification any time and may change it by channel or by program.  
         [0093]    If the data may be displayed ( 2008 ), it is displayed automatically ( 2009 ). If not, the data is not displayed ( 2010 ). The data not displayed may be stored in storage units such as a memory or a disk. The data is discarded if it is not stored. In this context, “display” means that, if the data is an executable program, the data is executed.  
         [0094]    In this embodiment, although neither a data display time is specified nor does the transmission format (FIG. 11) contain a data display time, a data display time may be added. When a data display time is added, whether or not data may be displayed is not checked immediately after it is received; instead, the data is once stored in the storage unit and, when the display time arrives, a check is made whether the data may be displayed.  
         [0095]    The data execution function  204  records the reception and display determination results, determined in the above reception flow, into the execution management file  206 . FIG. 19 shows the structure of the execution management file  206 . With the package number  2061  of the received packet as the key, the function stores the reception determination result into a selective reception  2062 , and the display determination result into a display  2063 . The function also stores the start and end times into a display start time  2064  and a display end time  2065 , respectively. The execution management manages the display (execution) of received data. In the display start time column, the time at which the data receiver  20  automatically displays data, as well as the time at which the user displays data, is recorded.  
         [0096]    The display  2063  of the execution management file  206  is not always required. If it is omitted, “displayed” is assumed if the value of the display end time  2065  is larger than the value of the display start time  2064 ; otherwise, “not displayed” is assumed.  
         [0097]    In the manner described above, data packets are sent from the data transmitter  10  to the data receivers  20 - 1 - 20 -n.  
         [0098]    Thus, the execution management files  206  recorded by all the data receivers  20 -n are sent to, and calculated by, the total calculator  30  at a regular interval or when the audience returns a response to received data. The data execution function  204  sends the contents of the execution management file  206  via the input/output management function  205 . This is called the transmission of program rating data.  
         [0099]    [0099]FIG. 21 shows the format of program rating data  215 . The program rating data  215  is composed of the following five items: a destination address  2151 , an audience ID  2152 , a package number  2153 , history data  2154 , and reply data  2155 . The destination address  2151 , preset in the data receiver  20 , is an address used to communicate with the total calculator  30 . The audience ID  2152 , usually obtained from the IC card device  238 , is an ID identifying the audience. The package number  2153  is the package number of a received packet. The history data  2154  is composed of the following four items: a selective reception  2062 , display  2063 , display start time  2064 , and display end time  2065 . The reply data  2155  is stored when the reception data requests the audience to reply and when the audience has replied.  
         [0100]    The display  2063  of the program rating data  215  is not always required. When it is omitted, “displayed” is assumed if the value of the display end time  2065  is larger than the value of the display start time  2064 ; otherwise, “not displayed” is assumed.  
         [0101]    The program rating data  215 , if collected from the receivers of a specific number of people, allows us to understand the status of audience and/or trend of audience. The collection ratio of program rating data on a package number indicates the reception ratio of the data.  
         [0102]    Combining the “selective reception” item in the program rating data with the contents of the packet management table  107  previously sent from the transmission station allows us to estimate which content code&#39;s data the audience received or rejected, that is, why the audience rejected the reception of the data.  
         [0103]    This is because the audience attribute may be estimated from the content code that is specified for him or her. The “display” item indicates whether the audience rejected the display or not. The “display start time” item indicates whether the data is displayed immediately after reception or at a later time. The “display end time” item allows us to estimate how much the audience is interested in the data.