Abstract:
A positioning apparatus for receiving a positioning standard code which is used as a standard of positioning from a positioning satellite, comprising: analysis assistance code generating means for generating an analysis assistance code for determining which positioning satellite corresponds to the positioning standard code based on the received positioning standard code; positioning standard code identifying means for analyzing the positioning standard code and the analysis assistance code, and identifying which positioning satellite corresponds to the positioning standard code; and current position information generating means for generating current position information indicating a current position based on an identified result by the positioning standard code identifying means.

Description:
[0001]     This application claims the priorities benefit under 35 U.S.C.§119 of Japanese Patent Application No. 2005-138093 filed on May 11, 2005, which is hereby incorporated in its entirety by reference.  
       BACKGROUND  
       [0002]     1. Technical Field  
         [0003]     The present invention relates to a positioning apparatus and a positioning method which use radio waves from positioning satellites.  
         [0004]     2. Related Art  
         [0005]     Conventionally, positioning systems for positioning a current position of each GPS (Global Positioning System) receiver using a satellite navigation system such as GPS have been used.  
         [0006]     Such GPS receiver receives a C/A (Clear and Acquisition or Coarse and Access) code, which is one of the pseudo random noise codes (hereinafter, referred to as PN (Pseudo random Noise code)) putted on radio waves from GPS satellites (hereinafter, referred to as satellite radio waves), based on satellite information indicating a GPS satellite orbit (rough satellite orbit information: almanac, accurate orbit information: ephemeris). The C/A code is a code serving as a positioning standard.  
         [0007]     The GPS receiver then identifies which GPS satellite transmits the C/A code, and calculates the distance (pseudo distance) between the GPS satellite and the GPS receiver based on the time at which the C/A code is transmitted and the time at which it is received. The GPS receiver then positions the position of the GPS receiver based on the pseudo distance of three or more of GPS satellites and the position of each GPS satellite on the satellite orbit (e.g., JP-A-10-339772).  
         [0008]     Here, since the above-mentioned satellite radio waves are subjected to PSK modulation by PN code such as the C/A code, spectral width expands. This causes degradation of signal to noise ratio (hereinafter, referred to as SNR (Signal to Noise Ratio)) of satellite radio waves, making it difficult to extract the C/A code.  
         [0009]     Accordingly, the GPS receiver receives C/A codes from the identical GPS satellite multiple times, and then integrates the sampling results of the C/A codes, thereby improving the SNR. Hereinafter, integration of the sampling results is simply referred to as integration. In addition, integration of codes and integration of the sampling results of codes are identical actions.  
         [0010]     However, since a C/A code is repeatedly transmitted for every 1 msec (ms), it takes 20 msec (ms) to receive it 20 times. This develops a problem that it requires a certain time determined by the transmission interval period of the C/A code to integrate the number of times required for extracting the C/A code.  
       SUMMARY  
       [0011]     Accordingly, an advantage of some aspects of the invention is to provide a positioning apparatus and a positioning method for integrating the number of times required f or extracting a positioning standard code without restrictions imposed by transmission interval period of positioning standard codes.  
         [0012]     In order to achieve the above object, a positioning apparatus for receiving positioning standard codes which is used as a standard of positioning from positioning satellites according to a first aspect of the invention includes: analysis assistance code generating means for generating analysis assistance codes for identifying which positioning apparatus corresponds to the positioning standard code based on the received positioning standard codes, positioning standard code identifying means for analyzing the positioning standard codes and the analysis assistance codes and identifying which positioning satellite corresponds to the positioning standard code, and current position information generating means for generating current position information indicating a current position based on the identified result by the positioning standard code identifying means.  
         [0013]     With the structure according to the first aspect of the invention, the positioning apparatus can generate analysis assistance codes for analyzing the positioning standard codes using the analysis assistance code generating means.  
         [0014]     The positioning apparatus can also analyze the positioning standard codes and the analysis assistance codes, and identify which positioning satellite corresponds to the positioning standard code using the positioning standard code identifying means.  
         [0015]     Accordingly, when receiving the positioning standard codes once, the positioning apparatus can generate the number of analysis assistance codes required for identifying which positioning satellite corresponds to the positioning standard code based on the positioning standard code. This means that it is unnecessary for the positioning apparatus to receive the number of positioning standard codes required for identifying which positioning satellite corresponds to the positioning standard code. Accordingly, the positioning apparatus can integrate the sampling results of the positioning standard codes required for extracting the positioning standard codes without restrictions imposed by transmission interval period of the positioning standard codes.  
         [0016]     This allows the positioning apparatus to integrate the number of times required for extracting the positioning standard codes without restrictions imposed by transmission interval period of the positioning standard codes.  
         [0017]     A second aspect of the invention is a positioning apparatus with a structure according to the first aspect of the invention, wherein the analysis assistance code generating means generates the analysis assistance codes so that the total number of the positioning standard codes and the analysis assistance codes equals the number required for identifying which positioning satellite corresponds to the positioning standard code.  
         [0018]     With the structure according to the second aspect of the invention, the analysis assistance code generating means can generate the sufficient number of analysis assistance codes required for identifying which positioning satellite corresponds to the positioning standard code.  
         [0019]     A third aspect of the invention is a positioning apparatus with the structure according to any of the first and the second aspect of the invention, wherein the analysis assistance code generating means generates the analysis assistance codes within a range of delay in which the positioning standard code identifying means can identify standard unit code which is a standard unit configuring the positioning standard codes.  
         [0020]     In order to identify which positioning satellite corresponds to the positioning standard code, it is necessary to integrate the standard unit codes with each other allocated at the identical position in the positioning standard codes.  
         [0021]     With the structure according to the third aspect of the invention, the analysis assistance code generating means can generate the analysis assistance codes within a range of delay in which the analysis means can identify standard unit code which is a standard unit configuring the positioning standard codes. Thus, the positioning standard code identifying means can identify which positioning satellite corresponds to the positioning standard code reliably.  
         [0022]     A fourth aspect of the invention is a positioning apparatus with the structure according to any of the first through the third aspect of the invention, wherein the analysis assistance code generating means generates the analysis assistance codes with respect to a part of the positioning standard code.  
         [0023]     It is possible to determine which positioning satellite corresponds to the positioning standard code by analyzing a part of the positioning standard code, not all of it.  
         [0024]     With the structure according to the fourth aspect of the invention, the analysis assistance code generating means can generate the analysis assistance codes with respect to a part of the positioning standard code. This allows the positioning standard code identifying means to reduce the time required for analysis and identify which positioning satellite corresponds to the positioning standard code.  
         [0025]     In order to achieve the above object, a positioning method according to a fifth aspect of the invention includes: an analysis assistance code generating step in which a positioning apparatus for receiving positioning standard code which is a positioning standard from a positioning apparatus generates analysis assistance code for determining which positioning satellite corresponds to the positioning standard code based on the received positioning standard code, a positioning standard code identifying step in which the positioning apparatus analyzes the positioning standard code and the analysis assistance code, and identifies which positioning satellite corresponds to the positioning standard code, and a current position information generating step in which the positioning apparatus generates current position information indicating a current position based on an identified result by the positioning standard code identifying step.  
         [0026]     With the structure according to the fifth aspect of the invention, as with the first aspect of the invention, it is possible to integrate the number of times required for extracting positioning standard codes without restrictions imposed by transmission interval period of positioning standard codes.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]     The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.  
         [0028]      FIG. 1  schematically shows a positioning system in an embodiment according to the invention.  
         [0029]      FIG. 2  schematically shows codes C 1  and the like.  
         [0030]      FIG. 3  schematically shows codes C 1  and the like.  
         [0031]      FIG. 4  schematically shows a main structure of a GPS apparatus.  
         [0032]      FIG. 5  schematically shows a main hardware structure of a terminal.  
         [0033]      FIG. 6  schematically shows a main software structure of the terminal.  
         [0034]      FIG. 7  schematically shows a flowchart of an operation example of the positioning system.  
         [0035]      FIG. 8  schematically shows a main structure of the GPS apparatus.  
         [0036]      FIG. 9  schematically shows codes C 1  and the like. 
     
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0037]     Hereinafter, with reference to the drawings, the preferred exemplary embodiments of the invention will be described in detail.  
         [0038]     The following embodiments are given various limitations that are preferable technically because they are the exemplary specific examples of the invention, however, the scope of the invention is not limited to these aspects unless there is a particular description to limit the invention in the following description.  
         [0039]      FIG. 1  schematically illustrates a positioning system  10  according to an embodiment of the invention.  
         [0040]      FIGS. 2 and 3  schematically illustrate codes C 1  and the like transmitted from GPS satellites  12   a  and the like.  
         [0041]     As illustrated in  FIG. 1 , the positioning system  10  includes positioning satellites, such as the GPS satellites  12   a,    12   b,    12   c  and  12   d.  The GPS  12   a  and the like transmit radio waves S 1 , S 2 , S 3  and S 4 , respectively, on which various codes are putted. One of these codes is C/A code. The codes C 1  through C 20  in  FIG. 2  are C/A codes. The codes C 1  through C 20  are, for example, the identical code continuously transmitted from the GPS satellite  12   a.  For example, the code C 1  is the C/A code transmitted prior to the code C 2 . The codes C 1  and the like are an example of positioning standard code. The codes C 1  and the like are also an example of a PRN (Pseudo Random Noise) code.  
         [0042]     The positioning system  10  includes a terminal  20 . The terminal  20  includes a GPS apparatus  30 , and thus can receive the codes C 1  and the like putted on the radio waves S 1  and the like from the GPS satellites  12   a  and the like.  
         [0043]     The terminal  20  then receives C/A codes from three or more of different GPS satellites  12   a  and the like, allowing positioning of a current position. The codes C 1  and the like have a cycle of 1 msec (ms), which corresponds to the distance of 300 kilometers (km). The codes C 1  and the like differ for each of the GPS satellites  12   a  and the like.  
         [0044]     First, the terminal  20  identifies which GPS satellite corresponds to the code C 1  or the like. Hereinafter, identification which GPS satellite corresponds to the code C 1  or the like is referred to as extraction of the code C 1  or the like or the C/A code. Next, the distance between each of the GPS satellites  12   a  and the like and the terminal  20  (hereinafter, referred to as pseudo distance) is calculated using light-speed propagation of the radio wave S 1  on which codes are putted based on the difference between the time at which the codes C 1  and the like are transmitted from each of the GPS satellites  12   a  and the like and the time at which the code C 1  is received. A current position is then positioned based on the position of each of the GPS satellites  12   a  and the like on the satellite orbit at the current time and the above-mentioned pseudo distance.  
         [0045]     It should be noted that four GPS satellites  12   a  and the like are illustrated in  FIG. 1 , however, the number of the GPS satellites  12   a  and the like may be three or five or more.  
         [0046]     As illustrated in  FIG. 3 ( a ), the code C 1  is configured with 1,023 chips P 1  through P 1023 . The chips P 1  and the like are a standard unit, which configures the code C 1  and indicates a numerical value of 0 or 1. The chips P 1  and the like are an example of standard unit code.  
         [0047]     In order to extract the C/A code, it is necessary to identify each chip P 1  or the like is either 0 or 1. Hereinafter, identification of each chip P 1  or the like being either 0 or 1 is referred to as identification of chip P 1  and the like. The identification of chip P 1  and the like is an example of analysis.  
         [0048]     However, since the above-mentioned radio waves S 1  and the like are subjected to PSK modulation by PN code such as C/A code, spectral width expands. This causes degradation of SNR, making it difficult to identify each chip P 1  or the like.  
         [0049]     Assuming that the GPS receiver receives the C/A code three times from the GPS satellite  12   a,  and integrates the sampling results of the C/A codes to improve the SNR, for example, as illustrated in  FIG. 3 ( b ), it takes (2+ 1/1023) msec (ms) to identify the chip P 1 . This is because the code  1  should be received first, the code  2  should then be received, and the chip P 1  section of the code C 3  should then be received in order to receive the chip P 1  three times. In other words, it takes a certain time determined by a cycle of the C/A code to receive the chip P 1 .  
         [0050]     With the following structure, the terminal  20  in the embodiment according to the invention can identify the chips P 1  and the like without restrictions imposed by a certain time determined by the cycle of the C/A code.  
         [0051]     Structure of GPS Apparatus  30   
         [0052]      FIG. 4  schematically illustrates a structure of the GPS apparatus  30 .  
         [0053]     As illustrated in  FIG. 4 , the GPS apparatus  30  includes an RF section  32  and a base band section  34 .  
         [0054]     The RF section  32  receives C/A codes using an antenna  32   a.  An amplifier LNA  32   b  amplifies the C/A codes. A mixer  32   c  then converts the frequency of the C/A codes. A delay circuit  32   d  including an IQ detector carries out IQ separation of the C/A codes. A/D converters  32   e   1  and  32   e   2  then converts the C/A codes subjected to IQ separation into digital signals, respectively.  
         [0055]     The base band section  34  receives the C/A codes converted into digital signals from the RF section  32 , samples and integrates each chip P 1  or the like (see  FIG. 3 ( a )), and correlates with the C/A codes stored in the base band section  34 , thereby identifying the received C/A codes.  
         [0056]     Main Hardware Structure of Terminal  20   
         [0057]      FIG. 5  schematically illustrates a main hardware structure of the terminal  20 .  
         [0058]     As illustrated in  FIG. 5 , the terminal  20  includes a computer, which is equipped with a bus  22 . A CPU (Central Processing Unit)  24 , a storage apparatus  26 , and the like are connected with the bus  22 . The storage apparatus may be a RAM (Random Access Memory), a ROM (Read Only Memory), or the like.  
         [0059]     An input apparatus  28 , the GPS apparatus  30 , a communication apparatus  36 , a display apparatus  38 , and a clock  40  are also connected with the bus  22 .  
         [0060]     Main Software Structure of Terminal  20   
         [0061]      FIG. 6  schematically illustrates a main software structure of the terminal  20 .  
         [0062]     As illustrated in  FIG. 6 , the terminal  20  includes a control section  100  for controlling each section, a GPS section  102  corresponding to the GPS apparatus  30  in  FIG. 5 , a communication section  104  corresponding to the communication apparatus  36 , a clock section corresponding to the clock  40 , and the like.  
         [0063]     The terminal  20  also includes a first storage section  110  for storing each program and a second storage section  150  for storing each pieces of information.  
         [0064]     As illustrated in  FIG. 6 , the terminal  20  stores satellite orbit information  152  in the second storage section  150 . The satellite orbit information  152  includes almanac  154  and ephemeris  156 . The almanac  154  is information indicating a rough orbit of all GPS satellites  12   a  and the like. The ephemeris  156  is information indicating an accurate orbit of each of the GPS satellites  12   a  and the like. The terminal  20  uses the almanac  154  and the ephemeris  156  for positioning.  
         [0065]     As illustrated in  FIG. 6 , the terminal  20  stores GPS signal receiving program  112  in the first storage section  110 . The GPS signal receiving program  112  is a program that the control section  100  receives the C/A codes putted on the radio wave S 1  from the GPS satellite  12   a  or the like using the GPS section  102 .  
         [0066]     The GPS apparatus  30  (see  FIG. 4 ) instructed by the control section  100  first receives the C/A codes using the antenna  32   a.  For example, it is assumed that the code C 1  is received from the GPS satellite  12   a  (see  FIG. 3 ( c )).  
         [0067]     The code C 1  is received by the delay circuit  32   d  passing through the LNA  32   b  and the mixer  32   c.    
         [0068]     The delay circuit  32   d  generates replica codes C 1 - 1  and C 1 - 2 , which are replicas of the code C 1 , based on the code C 1  (see  FIG. 3 ( c )). The replica codes C 1 - 1  and C 1 - 2  are codes for identifying which GPS satellite corresponds to the code C 1  by the base band section  34 . In other words, the replica codes C 1 - 1  and C 1 - 2  are an example of analysis assistance codes. The delay circuit  32   d  is an example of analysis assistance code generating means.  
         [0069]     As illustrated in  FIG. 3 ( c ), the delay circuit  32   d  generates the replica code C 1 - 1  having a 1-chip delay with respect to the code C 1 , and also generates the replica code C 1 - 2  having a 1-chip delay with respect to the replica code C 1 - 1 .  
         [0070]     The delay circuit  32   d  generates the replica codes C 1 - 1  and the like so that the total number of the code C 1  and the replica codes C 1 - 1  and the like equals the number required for identifying which GPS satellite corresponds to the code C 1  (hereinafter, referred to as the number required for code identification). The number required for code identification may be 20, for example, however, it is three herein for simplifying the description.  
         [0071]     The number required for code identification is not limited as in this embodiment, but may be changeable for each positioning based on the positioning conditions including receiving intensity of the radio waves S 1  and the like, and PDOP (Position Dilution Of Precision) and the like.  
         [0072]     The delay circuit  32   d  generates the code C 1  and the replica codes C 1 - 1  and the like within a range of delay in which the base band section  34  can identify the chip P 1  and the like. For example, when the base band section  34  recognizes that the chips P 1  and the like having a 1-chip delay, respectively, are the chips at the identical position in the code C 1  and the replica codes C 1 - 1  and the like, the replica codes C 1 - 1  and the like having a 1-chip delay, respectively, with respect to the code C 1  are generated as illustrated in  FIG. 3 ( c ).  
         [0073]     The invention is not limited to this embodiment, for example, when the base band section  34  recognizes that the chips P 1  and the like having a 2-chip delay, respectively, are the chips at the identical position in the code C 1  and the replica codes C 1 - 1  and the like, the replica codes C 1 - 1  and the like having a 2-chip delay, respectively, with respect to the code C 1  may be generated.  
         [0074]     The delay circuit  32   d  also generates the replica codes C 1 - 1  and the like with respect to a part of the code C 1 . It is not necessary to sample all chips P 1  and the like in the code C 1  but, for example, only 500 chips when the base band section  34  identifies which GPS satellite corresponds to the code C 1 . Accordingly, the delay circuit  32   d  replicates the code C 1  in a range required for the base band section  34  to identify which GPS satellite corresponds to the code C 1 .  
         [0075]     In  FIG. 3 ( c ), all 1,023 chips are duplicated for convenience of the description.  
         [0076]     The code C 1  and the replica codes C 1 - 1  and the like are subjected to IQ separation by the detector in the delay circuit  32   d,  and the results are transmitted to the A/D converters  32   e   1  and  32   e   2 , respectively. As soon as being generated, the code C 1  and the replica codes C 1 - 1  and the like converted into digital signals are then transmitted to the base band section  34 .  
         [0077]     In the base band section  34 , the code C 1  and the replica codes C 1 - 1  and the like are sampled in units of the chip P 1  or the like, and the sampling results are integrated. The integrated sampling results and the C/A codes stored in the base band section  34  are then correlated, thereby identifying which GPS satellite corresponds to the received code C 1 . In other words, the base band section  34  is an example of the positioning standard code identifying means.  
         [0078]     Here, the replica codes C 1 - 1  and the like are generated so as to have a 1-chip delay with respect to the code C 1 , respectively. Paying attention to the first chip P 1  in the codes C 1  and the like, it has a delay of 1/1023 msec (ms), respectively. Accordingly, the base band section  34  takes 3/1023 msec (ms) to receive the replica codes C 1 - 1  and C 1 - 2  after receiving the code C 1 .  
         [0079]     If we receive the C/A code three times, and receive the respective chips P 1  three times, for example, it takes (2+ 1/1023) msec (ms) as described above.  
         [0080]     On the other hand, according to this embodiment, the base band section  34  takes extremely shorter time, only 3/1023 msec (ms) to receive the replica codes C 1 - 1  and C 1 - 2  after receiving the code C 1 .  
         [0081]     The base band section  34  identifies which GPS satellite corresponds to the code  1 , as well as the phase of the code C 1 .  
         [0082]     As illustrated in  FIG. 6 , the terminal  20  stores positioning program  114  in the first storage section  110 . The positioning program  114  is a program that the control section  100  generates current position information  158  indicating a current position based on the identified results by the GPS section  102 . In other words, the positioning program  114  and the control section  100  are an example of the current position information generating means.  
         [0083]     The terminal  20  is configured as described above.  
         [0084]     As mentioned above, the terminal  20  can generate the replica codes C 1 - 1  and the like.  
         [0085]     The terminal  20  samples the code C 1  and the replica codes C 1 - 1  and the like, and can identify which GPS satellite corresponds to the code C 1 .  
         [0086]     Accordingly, when receiving the code C 1  once, the terminal  20  can generate the number of replica codes C 1 - 1  and the like required for identifying which GPS satellite corresponds to the code C 1  based on the code C 1 . This means that it is unnecessary for the terminal  20  to receive the number of codes C 1  and the like required for identifying which GPS satellite corresponds to the code C 1 . Thus, the terminal  20  may integrate the sampling results of the code C 1  and the replica codes C 1 - 1  and the like required for extracting the code C 1  without restrictions imposed by transmission interval period of the codes C 1  and the like.  
         [0087]     This allows the terminal  20  to integrate the number of times required for extracting the codes C 1  and the like without restrictions imposed by transmission interval period of the codes C 1  and the like.  
         [0088]     The terminal  20  also generates the replica codes C 1 - 1  and the like so that the total number of the code C 1  and the replica codes C 1 - 1  and the like equals the number required for identifying which GPS satellite corresponds to the code C 1 .  
         [0089]     This allows the terminal  20  to generate the sufficient number of replica codes C 1 - 1  and the like required for identifying which GPS satellite corresponds to the code C 1 .  
         [0090]     The terminal  20  also generates the replica codes C 1 - 1  and the like within a range of delay in which the base band section  34  can identify the chips P 1  and the like which are standard units configuring the code C 1 . In order to identify which GPS satellite corresponds to the code C 1  or the like, the chips P 1  and the like allocated at the identical position in the code C 1  and the replica codes C 1 - 1  and the like must be integrated with each other.  
         [0091]     The terminal  20  generates the replica codes C 1 - 1  and the like within a range of delay in which the base band section  34  can identify which GPS satellite corresponds to the code C 1  or the like. Accordingly, the base band section  34  can identify which GPS satellite corresponds to the code C 1  reliably.  
         [0092]     The terminal  20  also generates the replica codes C 1 - 1  and the like with respect to a part of the code C 1  or the like.  
         [0093]     As described above, it is possible to identify which GPS satellite corresponds to the code C 1  by sampling only a part of the code C 1 , not all of the code C 1 .  
         [0094]     The terminal  20  generates the replica codes C 1 - 1  and the like with respect to a part of the code C 1  or the like. This allows the terminal  20  to reduce the sampling time and identify which GPS satellite corresponds to the code C 1  or the like.  
         [0095]     The structure of the terminal  20  in the embodiment according to the invention is described above. The operation example is hereinafter described mainly using  FIG. 7 .  
         [0096]      FIG. 7  schematically illustrates a flowchart of an operation example of the terminal  20 .  
         [0097]     First, the terminal  20  receives a C/A code C 1  putted on the radio wave S 1  from the GPS satellite  12   a,  for example (step ST 1  in  FIG. 7 ).  
         [0098]     Subsequently, the terminal  20  generates the replica codes C 1 - 1  and the like (see  FIG. 3 ( c )) (step ST 2 ). The step ST 2  is an example of the analysis assistance code generating step.  
         [0099]     Afterwards, the terminal  20  integrates the original code C 1  and the replica codes C 1 - 1  and the like, and identifies which GPS satellite corresponds to the code C 1  (step ST 3 ). The step ST 3  is an example of the positioning standard code identifying step.  
         [0100]     The terminal  20  then positions a current position, and generates the current position information  158  (see FIG.  6 ) (step ST 4 ). The step ST 4  is an example of the current position information generating step.  
         [0101]     Next, the terminal  20  displays the current position information  158  on the display apparatus  38  (see  FIG. 5 ) (step ST 5 ).  
         [0102]     As mentioned above, the terminal  20  can integrate the number of times required for extracting the codes C 1  and the like without restrictions imposed by transmission interval period of the codes C 1  and the like.  
       Modified Example of the Embodiment  
       [0103]     Next, the modified example of the embodiment is described mainly using  FIGS. 8 and 9 .  
         [0104]      FIG. 8  schematically illustrates a structure of a GPS apparatus  30 A in the modified example of the embodiment.  
         [0105]      FIG. 9  schematically illustrates codes C 1  and the like.  
         [0106]     As illustrated in  FIG. 8 , the GPS apparatus  30 A includes a branch circuit  32   f.    
         [0107]     As illustrated in  FIG. 9 , the branch circuit  32   f  generates replica codes C 1 - 1  and C 1 - 2  without delay with respect to the code C 1 .  
         [0108]     This allows a base band section  34  to receive the code C 1  and the replica codes C 1 - 1  and C 1 - 2  simultaneously. Accordingly, the base band section  34  takes only 1/1023 msec (ms) to receive the respective chips P 1  in the code C 1  and the replica codes C 1 - 1  and C 1 - 2 . The base band section  34  can execute sampling for the respective chips P 1  in the code C 1  and the replica codes C 1 - 1  and C 1 - 2  at once.  
         [0109]     If we receive the C/A code three times, and receive the respective chips P 1  three times, for example, it takes (2+ 1/1023) msec (ms) to, as described above.  
         [0110]     On the other hand, according to this embodiment, the base band section  34  takes extremely shorter time, only 1/1023 msec (ms) to receive and sample the replica codes C 1 - 1  and C 1 - 2  after receiving the code C 1 .  
         [0111]     The present invention is not limited to the above-described respective embodiments. Further, the above-described respective embodiments may be combined with each other.