Abstract:
A position detecting system includes an RFID terminal configured to transmit an identification information signal by radio; a plurality of receiving devices configured to receive the identification information signal; and a position detecting server configured to receive a reception notification of the identification information signal from each of the receiving device and configured to estimate a position of the RFID terminal. The RFID terminal includes a part configured to perform radio transmission of a plurality of identification information signals having different radio strengths. The position detecting server includes a part configured to integrate the reception notifications of the identification information signals having different radio strengths and configured to estimate the position of the RFID terminal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a U.S. continuation application filed under 35 USC 111(a) claiming benefit under 35 USC 120 and 365(c) of PCT application JP05/003528, filed Mar. 2, 2005. The foregoing applications are hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention generally relates to position detecting systems and active RFID (Radio Frequency Identification) terminals. More particularly, the present invention relates to a position detecting system for position detecting by using an active RFID terminal and the RFID terminal.  
         [0004]     2. Description of the Related Art  
         [0005]      FIG. 1  is a structural view of an example of a related art position detecting system. As shown in  FIG. 1 , plural receivers  12   a  through  12   j  are fixed within a position detecting area  10 . In addition, an active RFID terminal  14  moves in the position detecting area  10 .  
         [0006]     The active RFID terminal  14  sends a identification information signal by itself within a designate time interval. A reaching area (receivable area) of the identification information signal is shown by a circle  15 . Because of this, the receivers  12   a ,  12   b ,  12   c , and  12   d  situated in the circle  15  receive the identification information signal from the active RFID terminal  14 .  
         [0007]     When each of the receivers  12   a  through  12   j  receives the identification information signal, ID information demodulated from the identification information signal is sent to a server  16  via, for example, a LAN (Local Area Network).  
         [0008]     When the server  16  receives the notification of the ID information from the receivers  12   a ,  12   b ,  12   c , and  12   d , which have received the identification information signal from the active RFID terminal  14 , the server  16  calculates center of gravity  17  of positions of the receivers  12   a ,  12   b ,  12   c , and  12   d  so as to estimate the center of gravity  17  as a present position of the active RFID terminal  14 .  
         [0009]      FIG. 2  is a block diagram of the RFID terminal  14  shown in  FIG. 1 . As show in  FIG. 2 , the ID information for identifying the RFID terminal is stored in an ID-ROM part  20 . A transmission control part  21  codes the ID information read from the ID-ROM part  20  and supplies coded ID information to the RF part  22  with a designated time interval. The RF part  22  modulates the coded ID information and transmits it as an identification information signal of a specific frequency from an antenna  23 .  
         [0010]      FIG. 3  is a structural view of another example of the related art position detecting system. In  FIG. 3 , parts that are the same as the parts shown in  FIG. 1  are given the same reference numerals, and explanation thereof is omitted.  
         [0011]     As shown in  FIG. 3 , when a server  18  receives the ID information from the receivers  12   a ,  12   b ,  12   c , and  12   d  receiving the identification information signal from the active RFID terminal  14 , the server  18  weights each of positions of the receivers  12   a ,  12   b ,  12   c , and  12   d  by using larger weights as the number of identification information signals received by the receivers  12   a ,  12   b ,  12   c , and  12   d  is larger. Then the server  18  calculates the center of gravity  19  so as to estimate the center of gravity  19  as a present position of the active RFID terminal  14 .  
         [0012]     Here, the number of receptions of the identification information signals by the receiver  12   c  near the active RFID terminal  14  is large. The number of receiving the identification information signal by the receiver  12   a  far from the active RFID terminal  14  is small. The present position of the active RFID terminal  14  is estimated by being biased to a side of the receiver  12   c  where the number of received signal is large by weighting the number of received signals so that the position estimation precision of the active RFID terminal  14  is improved.  
         [0013]     Patent Publication 1 mentioned below describes that an electric wave transmitted from the RFID is received by plural receivers so that the position of the RFID is specified by positions of the plural receivers.  
         [0014]     Patent Publication 2 mentioned below describes that an electric wave transmitted from the portable terminal is received by plural receivers so that the position of the portable terminal is specified based on each of received levels at which plural receivers receive.  
         [0015]     Patent Publication 3 mentioned below describes that an electric wave transmitted from the RFID is received by plural receivers and a position corresponding to the receiver closest to the RFID is specified as the position of the RFID based on the received radio strength of plural receivers.  
         [0016]     Patent Publication 4 mentioned below describes that an electric wave transmitted from the portable terminal is received by plural local control stations and the position of the portable terminal is specified by position of the local control station or received radio strength.  
         [0000]     [Patent Document 1] Japanese Laid-Open Patent Application Publication No. 10-124781  
         [0000]     [Patent Document 2] Japanese Laid-Open Patent Application Publication No. 8-307917  
         [0000]     [Patent Document 3] Japanese Laid-Open Patent Application Publication No. 11-224400  
         [0000]     [Patent Document 4] Japanese Laid-Open Patent Application Publication No. 11-169353  
         [0017]     However, in the above-discussed related art cases, the position of the RFID is specified based on the position of the receiver which receives the identification information signal or by weighting the number of receptions of the identification information signal to the position of the receiver. Therefore, there is limitation of precision for specifying the position of the RFID. In addition, in an area where the electric wave reaches, depending on the difference of frequency of the electric wave or reflection, there may be a position where the electric wave is not easily received by the receiver. This may cause degradation of precision for specifying the position of the RFID.  
       SUMMARY OF THE INVENTION  
       [0018]     Accordingly, embodiments of the present invention may provide a novel and useful position detecting system and RFID terminal solving one or more of the problems discussed above.  
         [0019]     More specifically, the embodiments of the present invention may provide a position detecting system whereby position specifying accuracy can be improved and a RFID terminal.  
         [0020]     One aspect of the present invention may be to provide a position detecting system, including an RFID terminal configured to transmit an identification information signal by radio; a plurality of receiving devices configured to receive the identification information signal; and a position detecting server configured to receive a reception notification of the identification information signal from each of the receiving device and configured to estimate a position of the RFID terminal; wherein the RFID terminal includes a part configured to perform radio transmission of a plurality of identification information signals having different radio strengths; and the position detecting server includes a part configured to integrate the reception notifications of the identification information signals having different radio strengths and configured to estimate the position of the RFID terminal.  
         [0021]     Another aspect of the present invention may be to provide a position detecting system, including: an RFID terminal configured to transmit an identification information signal by radio; a plurality of receiving devices configured to receive the identification information signal; and a position detecting server configured to receive a reception notification of the identification information signal from each of the receiving device and configured to estimate a position of the RFID terminal; wherein the RFID terminal includes a part configured to perform radio transmission of a plurality of identification information signals having different radio frequencies; and the position detecting server includes a part configured to integrate the reception notifications of the identification information signals having different radio frequencies and configured to estimate the position of the RFID terminal.  
         [0022]     Other aspect of the present invention may be to provide an RFID terminal of a position detecting system, in which the position detecting system an identification information signal transferred by radio from the RFID terminal is received by a plurality of receivers, and reception notification of the identification information signal from each of the receivers is received by a position detecting server, so that a position of the RFID terminal is estimated, the RFID terminal including a part configured to perform radio transmission of a plurality of the identification information signals having different radio strengths.  
         [0023]     Other aspect of the present invention may be to provide an RFID terminal of a position detecting system, in which position detecting system an identification information signal transferred by radio from the RFID terminal is received by a plurality of receivers, and reception notification of the identification information signal from each of the receivers is received by a position detecting server, so that a position of the RFID terminal is estimated, the RFID terminal including a part configured to perform radio transmission of a plurality of the identification information signals having different radio frequencies.  
         [0024]     Other aspect of the present invention may be to provide a position detecting system, including an RFID terminal configured to transmit an identification information signal by radio; a plurality of receiving devices configured to receive the identification information signal; and a position detecting server configured to receive a reception notification of the identification information signal from each of the receiving devices and configured to estimate the position of the RFID terminal; wherein the RFID terminal includes a part configured to perform radio transmission of a plurality of the identification information signals having different radio strengths and frequencies; and the position detecting server includes a part configured to integrate the reception notifications of the identification information signals having different radio frequencies and radio strengths and configured to estimate the position of the RFID terminal. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]      FIG. 1  is a structural view of an example of a related art position detecting system;  
         [0026]      FIG. 2  is a block diagram of a RFID terminal  14  shown in  FIG. 1 ;  
         [0027]      FIG. 3  is a structural view of another example of the related art position detecting system;  
         [0028]      FIG. 4  is a structural view of a position detecting system of a first embodiment of the present invention;  
         [0029]      FIG. 5  is a block diagram of an active RFID terminal  34  shown in  FIG. 4 ;  
         [0030]      FIG. 6  is a flowchart of a control process executed by a transmission control part  41 ;  
         [0031]      FIG. 7  is a flowchart of a position specifying process executed by a position detecting server  38 ;  
         [0032]      FIG. 8  is a view for explaining the first embodiment of the present invention;  
         [0033]      FIG. 9  is a view showing a display screen of the position detecting server  38 ;  
         [0034]      FIG. 10  is a structural view of a position detecting system of a second embodiment of the present invention;  
         [0035]      FIG. 11  is a block diagram of an active RFID terminal  54  shown in  FIG. 10 ;  
         [0036]      FIG. 12  is a flowchart of a control process executed by a transmission control part  61 ;  
         [0037]      FIG. 13  is a flowchart of a position specifying process executed by a position detecting server  58 ;  
         [0038]      FIG. 14  is a view for explaining the second embodiment of the present invention;  
         [0039]      FIG. 15  is a view showing a display screen of the position detecting server  58 ;  
         [0040]      FIG. 16  is a schematic view showing an example where the first embodiment of the present invention is applied; and  
         [0041]      FIG. 17  is a view showing a display screen of the position detecting server  38 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0042]     A description will now be given, with reference to  FIG. 1  through  FIG. 14 , of embodiments of the present invention.  
         [0043]     A description will be given briefly below, with reference to  FIG. 4  through  FIG. 17 .  
       First Embodiment of the Present Invention  
       [0044]      FIG. 4  is a structural view of a position detecting system of a first embodiment of the present invention. As shown in  FIG. 4 , plural receivers  32   1  through  32   3  are fixed within a position detecting area  30 . In addition, an active RFID terminal  34  moves in the position detecting area  30 .  
         [0045]     The active RFID terminal  34  transmits identification information signals with plural kinds (for example, two kinds) of radio strength at a designated time interval. Reaching areas (receivable areas) of a first identification information signal having a high radio strength and a second identification information signal having a low radio strength are shown by circles  35  and  36 . The receivers  32   1  through  32   3  situated in the circle  35  receive the first identification information signal having high radio strength from the active RFID terminal  34 . Only the receiver  32   1  situated in the circle  36  receives the second identification information signal having low radio strength. When each of the receivers  32   1  through  32   3  receives the first identification information signal or the second identification information signal, ID information demodulated from the first identification information signal or the second identification information signal is reported to the position detecting server  38  via, for example, a LAN (Local Area Network).  
         [0046]      FIG. 5  is a block diagram of the active RFID terminal  34  shown in  FIG. 4 . As shown in  FIG. 5 , the ID information for identifying the RFID terminal is stored in an ID-ROM part  40 . A transmission control part  41  codes the ID information read from the ID-ROM part  40  and supplies the coded ID information to the RF part  42  with a designated time interval.  
         [0047]     The RF part  42  modulates the coded ID information and transmits it as an identification information signal of a specific frequency to an attenuator part  43 . The attenuator part  43  switches attenuation to the identification information signal by control of the transmission control part  41  so that the first identification information signal having no attenuation and the second identification information having 50% attenuation are mutually supplied to a non-directional antenna  44  so that ration transmission is made.  
         [0048]      FIG. 6  is a flowchart of a control process executed by a transmission control part  41 . As shown in  FIG. 6 , a timer is set in step S 10 . Whether time indicated by the timer is a transmission time to the RF part  42  is determined in step S 1 . When the time becomes the transmission time, the ID information is read from the ID-ROM part  40  in step S 12  and the ID information is coded in step S 13 .  
         [0049]     Next, whether it is time for turning on the attenuator part  43 , namely second identification information signal output timing, is determined in step S 14 . In a case where it is the time for turning on the attenuator part  43 , the attenuator part  43  is turned on in step S 15 . In a case where it is not the time for turning on the attenuator part  43 , the attenuator part  43  is turned off in step S 16 . Next, the coded ID information is supplied to the RF part  42  in step S 17  so that the identification information signal of the specific frequency modulated by the RF part  42  is transmitted.  
         [0050]      FIG. 7  is a flowchart of a position specifying process executed by a position detecting server  38 . As shown in  FIG. 7 , notification of the ID information is received from a single or plural receivers situated in the position detecting area  30  in step S 20  so that a center A of gravity of positions of the receivers receiving the notification is calculated.  
         [0051]     Next, whether a process timing of this time is a time for outputting the first identification information signal of the active RFID terminal  34  is determined in step S 21 . If the number of receivers reporting the same ID information at the process timing of this time is greater than the number of receivers reporting the same ID information at the process timing of last time, it is determined that it is the time for outputting the first identification information signal of the active RFID terminal  34 .  
         [0052]     In a case where the process timing of this time is the time for outputting the first identification information signal, in step S 22 , a weighting factor α is applied to the center of gravity A of this time so that the center of gravity B and the center of gravity C of last time are calculated. This center of gravity C is estimated as the present position of the active RFID terminal  34 .  
         [0053]     On the other hand, in a case where the process timing of this time is not the time for outputting the first identification information signal, in step S 23 , a weighting factor α is multiplied to the center of gravity B of last time so that the center of gravity A of this time and the center of gravity C of last time are calculated. This center of gravity C is estimated as the present position of the active RFID terminal  34 .  
         [0054]     After this, in step S 24 , the center of gravity A is renewed by holding the center of gravity A as the center of gravity B of last time so that this process is ended.  
         [0055]     Here, the weighting factor α is calculated by dividing the radius of the circle where the first identification information signal reaches with the radius of the circle where the second identification information signal reaches.  
         [0056]     As shown in  FIG. 4 , the identification information signals with high radio strength from the active RFID terminal  34  are received by the receivers  32   1  through  32   3  situated in the circle  35  so that the position  39  of the center of gravity is calculated. In addition, the identification information signal with low radio strength from the active RFID terminal  34  is received by only the receiver  32   1  situated in the circle  36  so that the position of the center of gravity is the position of the receiver  32   1 . In this case, the position  39  of the center of gravity and the position  40  of center of gravity where the position of the receiver  32   1  is weighted are estimated as the present position of the RFID terminal  34  so that position specifying accuracy can be improved.  
         [0057]      FIG. 8  is a view for explaining the first embodiment of the present invention. A case shown in  FIG. 8  where plural receivers  32   1  through  32   n  are situated in a certain area and a person holding the active RFID terminal  34  moves from the position of the receiver  32   6  to the position of the receiver  32   4  is discussed.  
         [0058]     (1) In the vicinity of the receiver  32   6 , the first identification information signal with high radio strength from the active RFID terminal  34  is received by the receivers  32   2 ,  32   3 ,  32   5 , and  32   6  and the second identification information signal with low radio strength is received by the receivers  32   6 . Because of this, as shown in  FIG. 9 , a person  42  holding the RFID terminal  34  is displayed near the receiver  32   6  on the display screen of the position detecting server  38 . Here,  FIG. 9  is a view showing a display screen of the position detecting server  38 .  
         [0059]     (2) Next, if the person holding the RFID terminal  34  moves to a side of the receivers  32   5 , the first identification information signal is received by the receivers  32   2  and  32   5 , and  32   6  and the second identification information signal is received by only the receivers  32   5 . Because of this, the person  42  holding the RFID terminal  34  is displayed near the receiver  32   5  on the display screen of the position detecting server  38 .  
         [0060]     (3) As the person holding the RFID terminal  34  moves, the receiver receiving the identification information signal moves. Finally, the first identification information signal is received by the receivers  32   1 ,  32   4 , and  32   5 , and the second identification information signal is received by only the receivers  32   4 . Because of this, the person  42  holding the RFID terminal  34  is displayed near the receiver  32   4  on the display screen of the position detecting server  38 .  
         [0061]     Thus, it is possible to implement position detecting with high precision so that movement of the person  42  holding the RFID terminal  34  is displayed near the receiver  32   4  on the display screen of the position detecting server  38 , smoothly and accurately.  
       Second Embodiment of the Present Invention  
       [0062]      FIG. 10  is a structural view of a position detecting system of a second embodiment of the present invention. As shown in  FIG. 10 , plural receivers  52   1  through  52   3  are fixed within a position detecting area  50 . In addition, an active RFID terminal  54  moves in the position detecting area  50 .  
         [0063]     The active RFID terminal  54  transmits identification information signal with plural kinds (for example, two kinds) of frequencies at a designated time interval. Reaching areas (receivable areas) of a identification information signal of a first frequency (for example, several hundreds MHz) are, for example, inside a circle  55   a , areas of a circle  55   a  and a circle  55   b , and areas of a circle  55   c  and a circle  55   d . Reaching areas (receivable areas) of a identification information signal of a second frequency (for example, several GHz) are, for example, inside a circle  55   a , and areas of a circle  55   b  and a circle  55   c.    
         [0064]     The receivers  52   1  and  52   2  situated in the circles  55   c  and  55   d  receive the first identification information signal having the first frequency from the active RFID terminal  34 . Only the receiver  52   3  situated in the circles  55   b  and  55   c  receives the identification information signal having a second frequency from the active RFID terminal  34 .  
         [0065]     When each of the receivers  52   1  through  52   3  receives the identification information signal, ID information demodulated from the identification information signal is reported to the position detecting server  58  via, for example, a LAN (Local Area Network).  
         [0066]      FIG. 11  is a block diagram of the active RFID terminal  54  shown in  FIG. 10 . As shown in  FIG. 10 , the ID information for identifying the RFID terminal is stored in an ID-ROM part  60 . A transmission control part  61  encodes the ID information read from the ID-ROM part  60  and supplies the coded ID information to the RF part  42  with a designated time interval. A selection part  62  mutually switches the RF part  63   a  or the RF part  63   b  as a part where the identification information signal should be supplied, by control of the transmission control part  61 .  
         [0067]     The RF part  63   a  modulates the coded ID information supplied from the selection part  62  and transmits it by radio as an identification information signal of a first frequency from non-directional antenna  64   a . The RF part  63   b  modulates the coded ID information supplied from the selection part  62  and transmits it by radio as an identification information signal of a first frequency from non-directional antenna  64   b.    
         [0068]     In a case where the RF parts  63   a  and  63   b  under a structure shown in  FIG. 11  output first and second identification information signal having different radio strength at the same specific frequency, this can be applied to the first embodiment of the present invention.  
         [0069]      FIG. 12  is a flowchart of a control process executed by the transmission control part  61 . As shown in  FIG. 12 , a timer is set in step S 30 . Whether time indicated by the timer is a transmission time to the RF part  62  is determined in step S 31 . When the time becomes the transmission time, the ID information is read from the ID-ROM part  60  in step S 32  and the ID information is encoded in step S 33 .  
         [0070]     Next, whether it is time for selecting the RF part  63   a  is determined in step S 34 . In a case where it is the time for selecting the RF part  63   a , the part to be supplied the identification information signal is set in the selection part  62  in step S 35 . In a case where it is not the time for selecting the RF part  63   b , the part to be supplied the identification information signal is set in the selection part  62  in step S 36 . Next, the ID information is supplied to the RF part  63   a  or the RF part  63   b  selected by the selection part  62  in step S 37  so that the identification information signal of the specific frequency modulated by the RF part  42  is transmitted.  
         [0071]      FIG. 13  is a flowchart of a position specifying process executed by a position detecting server  58 . The notification of the ID information is received from one or more receivers in the position detection area  50  in step S 40  and the receiver notifying reception of the ID information receiving of the last time is added to the receiver notifying reception of the ID information receiving of this time. After that, as the number of receptions of the identification information signal of each of the receivers compared to the same ID information becomes larger, the larger weight is used for weighting the position of the corresponding receivers so that the position D of the center of gravity is calculated. This position D of the center of gravity is estimated as the present position of the active RFID terminal  34 .  
         [0072]     As shown in  FIG. 7 , notification of the ID information is received from a single or plural receivers situated in the position detecting area  30  in step S 20  so that a center of gravity A of a position of each of the receivers receiving the notification is determined.  
         [0073]     Next, in step S 41 , renewal is made by holding the receiver of the ID information receiving notification of this time as the receiver of the ID information receiving notification of the last time so that this process is ended.  
         [0074]     As shown in  FIG. 10 , the identification information signal at a timing of the first frequency is transmitted from the active RFID terminal  54  by the receivers  52   1  and  52   2  situated in the area of the circle  55   c  and circle  55   d , and the identification information signal at a timing of the second frequency is transmitted from the active RFID terminal  54  by the receiver  52   3  situated in the area of the circle  55   b  and circle  55   c.    
         [0075]     In this embodiment, the information reception notification of the receivers  52   1  and  52   2  and the ID information reception notification of the receiver  52   3  are integrated so that the position  57  of the center of gravity obtained from the receivers  52   1 ,  52   2  and  52   3  is estimated as the present position of the active RFID  54  and position specifying accuracy can be improved.  
         [0076]     Here, a case shown in  FIG. 14  where plural receivers  52   1  through  52   n  are situated in a certain area and a person holding the active RFID terminal  54  moves from the position of the receiver  52   6  to the position of the receiver  52   4  is discussed.  FIG. 14  is a view for explaining the second embodiment of the present invention.  
         [0077]     (1) In the vicinity of the receiver  52   6 , the identification information signal of the first frequency from the active RFID terminal  54  is received by the receivers  52   2  and  52   3  and the identification information signal with the second frequency is received by the receivers  52   5  and  52   6 . Because of this, as shown in  FIG. 15 , a person  70  holding the RFID terminal  54  is displayed near the receiver  52   6  on the display screen of the position detecting server  38 . Here,  FIG. 15  is a view showing a display screen of the position detecting server  58 ;  
         [0078]     (2) Next, if the person holding the RFID terminal  35  moves to a side of the receivers  52   5 , the identification information signal of the first frequency and the identification information signal of the second frequency are received by the receivers  52   2  and  52   5  situated in the receiving area of the frequencies. Because of this, the person  70  holding the RFID terminal  54  is displayed near the receiver  52   5  on the display screen of the position detecting server  58 .  
         [0079]     (3) As the person  70  holding the RFID terminal  54  moves, the receiver receiving the identification information signal moves. Finally, the identification information signal of the first frequency is received by the receivers  52   1 , and  52   5 , and the identification information signal of the second frequency is received by only the receivers  52   4 . Because of this, the person  70  holding the RFID terminal  54  is displayed near the receiver  52   4  on the display screen of the position detecting server  58 .  
         [0080]     Thus, it is possible to implement position detecting with high precision so that movement of the person  70  holding the RFID terminal  54  is displayed on the display screen of the position detecting server  58 , smoothly and accurately.  
         [0081]     In this embodiment, a time for outputting the identification information signal of the first frequency from the active the RFID terminal  54  is different from a timing for outputting the identification information signal of the second frequency from the active the RFID terminal  54 . However, the present invention is not limited to this. The identification information signal of the first frequency and the identification information signal of the second frequency may be output concurrently.  
       An Example where the First Embodiment of the Present Invention is Applied  
       [0082]      FIG. 16  is a schematic view showing an example where the first embodiment of the present invention is applied.  FIG. 17  is a view showing a display screen of the position detecting server  38 . In this example, plural receivers  32   1  through  32   n  are situated in a certain area and a person holding the active RFID terminal  34  moves is discussed. In this example, a service is implemented where useful information about a store is automatically provided by portable e-mail when the person holding the active RFID terminal  34  passes in the vicinity of a store such as a convenient store  90  or a facility such as a sports ground.  
         [0083]     (1) When the person  80  holding the RFID terminal  34  moves in the vicinity of the convenience store  90 , the identification information signal transmitted from the active RFID terminal  34  is received by the receiver  32   1 ,  32   4  and  32   5  situated in the vicinity of the RFID terminal  34 , and the information is forwarded to the position detecting server  38 .  
         [0084]     (2) The position detecting server  38  specifies the position of the active RFID terminal  34  from the positions of the receiver  32   1 ,  32   4  and  32   5  so as to search whether there is a store or facility near the active RFID terminal  34 , the store or facility being registered in advance.  
         [0085]     (3) In a case where there is a store or facility near the active RFID terminal  34 , the store or facility being registered in advance, registered advertisement information (good buy information in a case of the convenience store) is sent to an e-mail address of a portable phone  81  of the person  80  holding the RFID terminal via the Internet.  
         [0086]     The advertisement information sent via a portable phone system  82  is received by the portable phone  81  of the person  80  holding the RFID terminal so that the advertisement information can be known.  
         [0087]     Thus, it is possible for the person  80  holding the RFID terminal  34  to have sent out the advertisement information registered in advance such as the shop or the facility in real time when passing in the vicinity of the store or facility.  
         [0088]     As discussed above, in the first embodiment of the present invention, plural identification information signals having different radio strengths are output from the active RFID terminal. In the second embodiment of the present invention, plural identification information signals having different radio frequencies are output from the active RFID terminal. There embodiments may be integrated so that plural identification information signals having different radio strengths and frequencies are output from the active RFID terminal. In this case, a structure of the active RFID terminal is the same as that shown in  FIG. 11 .  
         [0089]     The attenuator part  43  discussed above corresponds to an attenuation switching part of claims mentioned below. The RF part  63   a  discussed above corresponds to a first modulating part of claims mentioned blow. The RF part  63   b  discussed above corresponds to a second modulating part of claims mentioned blow. A selection part  62  discussed above corresponds to a selection part of claims mentioned blow.  
         [0090]     The present invention can be applicable to a technical field, especially, requiring position information with high precision. For example, the present invention can be applied in various ways such as confirming a place in a building, confirming a lost child in a play facility, or searching for a person who has wandered away from an old people&#39;s home.  
         [0091]     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.