JP2007278864A - Position measuring instrument, control method for the position measuring instrument, control program for the position measuring instrument, and computer-readable recording medium for therein storing control program for the position measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position measuring instrument or the like accurately measuring a present position, even in the middle of incoherent processing. <P>SOLUTION: This position measuring instrument 20 receives a basic positioning code from a transmission source and performs correlation processing, comprising coherent processing and incoherent processing to measure the present position. This measuring instrument 20 comprises a basic information calculation means for calculating basic information including the phase of the positioning code and signal intensity in receiving the positioning code, a reliability calculation means calculating the reliability of the phase, based on the signal intensity, a reliability evaluation means evaluating the reliability, and an incoherent processing midway position measuring means for measuring the present position in the middle of the incoherent processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a positioning device that uses radio waves from a transmission source, a positioning device control method, a positioning device control program, and a computer-readable recording medium that records the positioning device control program.

Conventionally, a positioning system that measures the current position of a GPS receiver by using, for example, a GPS (Global Positioning System) that is a satellite navigation system has been put into practical use.
This GPS receiver uses radio waves from GPS satellites (hereinafter referred to as satellite radio waves) based on navigation messages (including approximate satellite orbit information: almanac, precision satellite orbit information: ephemeris, etc.) indicating the orbits of GPS satellites. A C / A (Clear and Acquisition or Coarse and Access) code, which is one of pseudo noise codes (hereinafter referred to as PN (Psuedo random noise code) codes), is received. The C / A code is a code that is the basis of positioning.
The GPS receiver specifies the GPS satellite from which the C / A code is transmitted, and, for example, based on the transmission time and reception time of the C / A code, the GPS satellite and the GPS reception are performed. The distance of the machine (pseudo distance) is calculated. The GPS receiver measures the position of the GPS receiver based on the pseudoranges of three or more GPS satellites and the position of each GPS satellite on the satellite orbit (Japanese Patent Laid-Open No. Hei 10-2010). No. 339772).
In order to receive a signal from a GPS satellite, it is necessary to match the phase of the received C / A code and the replica C / A code generated inside the GPS receiver.
Further, the pseudo distance is calculated by specifying the phase of the received C / A code. That is, the C / A code has a bit rate of 1.023 Mbps and the code length is 1023 chips. Therefore, it can be considered that the C / A code runs side by side at intervals of about 300 kilometers (km), which is the distance traveled by radio waves in 1 millisecond (ms). Therefore, the number of C / A codes between the GPS satellite and the GPS receiver is calculated from the position of the GPS satellite on the satellite orbit and the approximate position of the GPS receiver, and the phase of the C / A code is calculated. If specified, the pseudo distance can be calculated.
In order to match the phase of the received C / A code with the phase of the replica C / A code generated inside the GPS receiver, correlation processing is performed while shifting the phase of the replica C / A code and the reception intermediate (IF) frequency. It has been broken.
This correlation processing is composed of coherent and incoherent.
Coherent is a process of synchronously integrating the received C / A code and calculating a correlation result with each chip of the replica C / A code. An output value obtained by coherent processing is called a coherent value. For example, if the coherent time is 20 msec, a coherent value at a time of 20 msec is calculated. As a result of the coherent processing, a correlated phase and a coherent value are output.
Incoherent is a process of calculating an incoherent value by integrating the coherent values. Since the C / A code is modulated by the navigation message, the coherent value deteriorates when the coherent time is increased. For this reason, after limiting the coherent time to a certain time, incoherent integration of coherent values is performed (for example, Patent Document 1).
JP-A-2005-321301

However, although the signal intensity from the GPS satellite is weak, the degree thereof varies, and for example, a C / A that can be used for positioning without requiring an incoherent time of, for example, 1 second (s). There is a possibility that the phase of the code can be obtained. In this case, there is a problem that positioning is delayed when the incoherent time has elapsed.
In this specification, “signal strength” is used synonymously with “radio wave strength”.

  Therefore, the present invention provides a positioning device that can accurately measure the current position even in the middle of incoherence, a positioning device control method, a positioning device control program, and a computer reading that records a positioning device control program. An object is to provide a possible recording medium.

  According to the first aspect of the present invention, there is provided a positioning device that receives a positioning basic code from a transmission source, performs a correlation process including coherent and incoherent, and measures a current position. Basic information calculation means for calculating basic information including the phase of the code and the signal strength of the positioning basic code, reliability calculation means for calculating the reliability of the phase based on the signal strength, and the reliability A positioning device comprising: a reliability evaluation unit to evaluate; and an incoherent midway positioning unit that performs positioning of a current position in the middle of the incoherent based on an evaluation result of the reliability evaluation unit. Achieved.

According to the configuration of the first invention, since the positioning device has the incoherent midway positioning unit, the current position is measured in the middle of the incoherent based on the evaluation result of the reliability evaluation unit. be able to.
That is, the positioning device can perform positioning even in the middle of the incoherent if the reliability of the phase is sufficient.
Thereby, even in the middle of incoherence, the current position can be measured with high accuracy.

  According to a second aspect of the present invention, in the configuration of the first aspect of the invention, the basic information storage unit stores the basic information in the storage unit every time the basic information is generated, and the phase stored in the storage unit. A predicted phase calculating means for calculating a predicted phase at the current time; and a phase correcting means for correcting the phase at the current time based on the predicted phase and calculating a corrected phase. It is a positioning device.

  According to the configuration of the second aspect of the invention, since the positioning device has the phase correction unit, positioning can be performed with higher accuracy even during incoherence.

  According to a third aspect of the present invention, in the configuration of the first aspect or the second aspect, the basic information includes a reception frequency when the positioning basic code is received, and the predicted phase calculation means When the phase cannot be calculated in the positioning device, the positioning device is configured to predict the phase at the current time based on the phase calculated before the current time and the reception frequency. It is.

  According to the configuration of the third invention, when the phase cannot be calculated at the current time, positioning can be performed even in the middle of incoherence.

  According to a fourth aspect of the present invention, in the configuration according to the second aspect or the third aspect, the predicted phase calculation unit is configured to predict a predicted phase at a current time based on all the phases stored in the storage unit. It is the positioning apparatus characterized by the structure which calculates.

  According to the configuration of the fourth aspect of the invention, the phase at the current time can be corrected based on as many of the predicted phases as possible, so that the accuracy of the corrected phase is improved.

  According to a fifth invention, in any one of the configurations of the second invention to the fourth invention, the predicted phase at the current time is determined according to whether or not the deviation from the phase at the current time is within a predetermined allowable range. It is a positioning apparatus characterized by having a predicted phase evaluation means for determining whether or not to use for phase correction.

  According to the configuration of the fifth invention, since the predicted phase can be selected, the accuracy of the corrected phase is further improved.

According to a sixth aspect of the present invention, in the configuration according to any one of the second to fourth aspects, the prediction phase calculation means is “prediction CP _t = CP _(t−dt) + F (Doppler _(t−dt) ) × The positioning device is configured to calculate the predicted phase using an expression “dt”.

  A seventh invention is a positioning device according to any one of the first to sixth inventions, wherein the transmission source is a positioning satellite including a GPS (Global Positioning System) satellite.

  According to an eighth aspect of the present invention, there is provided a positioning device that receives a positioning basic code from a transmission source, performs a correlation process including coherent and incoherent, and determines a current position. A basic information calculation step for calculating basic information including a phase and a signal strength of the positioning basic code; and a reliability evaluation step in which the positioning device evaluates the reliability of the corrected phase based on the signal strength; The positioning device has an incoherent midway positioning step for positioning the current position in the middle of the incoherent based on the evaluation result of the reliability evaluation means. Achieved by:

  According to the configuration of the eighth invention, as in the configuration of the first invention, the current position can be accurately measured even in the middle of incoherence.

  According to the ninth aspect of the present invention, there is provided a positioning device that receives a positioning basic code from a transmission source, performs a correlation process including coherent and incoherent, and determines a current position. A basic information calculating step for calculating basic information including a phase of a basic code and a signal strength of the positioning basic code; and a reliability with which the positioning device evaluates the reliability of the corrected phase based on the signal strength Positioning characterized in that an evaluation step and the positioning device execute an incoherent midway positioning step of positioning a current position in the middle of the incoherent based on an evaluation result of the reliability evaluation unit. Achieved by the device control program.

  According to the tenth aspect of the present invention, there is provided a positioning device that receives a positioning basic code from a transmission source, performs a correlation process consisting of coherent and incoherent, and determines a current position. A basic information calculating step for calculating basic information including a phase of a basic code and a signal strength of the positioning basic code; and a reliability with which the positioning device evaluates the reliability of the corrected phase based on the signal strength Positioning characterized in that an evaluation step and the positioning device execute an incoherent midway positioning step of positioning a current position in the middle of the incoherent based on an evaluation result of the reliability evaluation unit. This is achieved by a computer-readable recording medium that records a control program for the apparatus.

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
The embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

FIG. 1 is a schematic diagram illustrating a terminal 20 and the like according to the embodiment of this invention.
As shown in FIG. 1, the terminal 20 can receive radio waves S1, S2, S3 and S4 from GPS satellites 12a, 12b, 12c and 12d which are positioning satellites. The GPS satellite 12a or the like is an example of a transmission source.
Various codes (codes) are carried on the radio wave S1 and the like. One of them is the C / A code Sca. The C / A code Sca is a signal having a bit rate of 1.023 Mbps and a bit length of 1,023 bits (= 1 msec). The C / A code Sca is composed of 1,023 chips. The terminal 20 is an example of a positioning device that measures the current position, and performs positioning of the current position using the C / A code. This C / A code Sca is an example of a positioning basic code.

  Moreover, there are almanac Sal and ephemeris Seh as information put on the radio wave S1 and the like. Almanac Sal is information indicating the approximate satellite orbit of all the GPS satellites 12a and the like, and Ephemeris Seh is information indicating the precise satellite orbit of each of the GPS satellites 12a and the like. Almanac Sal and Ephemeris Seh are collectively called navigation messages.

For example, the terminal 20 can receive C / A codes from three or more different GPS satellites 12a and the like, and can determine the current position.
First, the terminal 20 specifies to which GPS satellite the received C / A code corresponds. Next, by identifying the phase of the C / A code, the distance between each GPS satellite 12a and the like and the terminal 20 (hereinafter referred to as a pseudorange) is calculated. Subsequently, the current position is calculated based on the position of each GPS satellite 12a or the like on the satellite orbit at the current time and the pseudo distance described above.
The terminal 20 performs a coherent process and an incoherent process, which will be described later, in order to identify the phase of the C / A code.
Note that, unlike the present embodiment, the terminal 20 may perform positioning using, for example, radio waves from a mobile phone communication base station. Further, unlike the present embodiment, the terminal 20 may perform positioning by receiving radio waves from a LAN (Local Area Network).

(Main hardware configuration of terminal 20)
FIG. 2 is a schematic diagram showing a main hardware configuration of the terminal 20.
As shown in FIG. 2, the terminal 20 has a computer, and the computer has a bus 22. A CPU (Central Processing Unit) 24, a storage device 26, and the like are connected to the bus 22. The storage device 26 is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), or the like.
In addition, an input device 28, a power supply device 30, a GPS device 32, a display device 34, a communication device 36, and a clock 38 are connected to the bus 22.

(About the configuration of the GPS device 32)
FIG. 3 is a schematic diagram showing the configuration of the GPS device 32.
As shown in FIG. 3, the GPS device 32 includes an RF unit 32a and a baseband unit 32b.
The RF unit 32a receives the radio wave S1 and the like with the antenna 33a. The amplifier LNA 33b amplifies a signal such as a C / A code carried on the radio wave S1 or the like. Then, the mixer 33c down-converts the signal frequency. Then, the quadrature (IQ) detector 33d performs IQ separation on the signal. Subsequently, the AD converters 33e1 and 33e2 are configured to convert the IQ-separated signals into digital signals, respectively.
The baseband unit 32b receives a signal converted into a digital signal from the RF unit 32a, samples and accumulates each chip (not shown) of the signal, and generates a replica C / A code generated by the baseband unit 32b. It is comprised so that the correlation may be taken. The baseband unit 32b has, for example, 128 correlators (not shown) and accumulators (not shown), and can perform correlation processing at 128 phases simultaneously.
The correlation process is composed of coherent and incoherent.
The correlator is configured to perform coherent processing. The accumulator is configured to perform incoherent processing.
Coherent is a process in which the baseband unit 32b correlates each chip of the received C / A code and replica C / A code.
For example, if the coherent time is 20 msec, the C / A code is synchronously accumulated at a time of 20 msec, and the correlation value between the accumulated C / A code and the replica C / A code is calculated. As a result of the coherent processing, a correlated phase and a correlation value are output.
Incoherent is a process of calculating an incoherent value by accumulating correlation values of coherent results.
As a result of the correlation processing, the phase output by the coherent processing and the incoherent value are output.

(About main software configuration of terminal 20)
FIG. 4 is a schematic diagram showing a main software configuration of the terminal 20.
As illustrated in FIG. 4, the terminal 20 includes a control unit 100 that controls each unit, a GPS unit 102 that corresponds to the GPS device 32 in FIG. 2, a clock unit 104 that corresponds to the clock 38, and the like.
The terminal 20 also includes a first storage unit 110 that stores various programs and a second storage unit 150 that stores various information.

As illustrated in FIG. 4, the terminal 20 stores a navigation message 152 in the second storage unit 150. The navigation message 152 includes an almanac 152a and an ephemeris 152b.
The terminal 20 uses the almanac 152a and the ephemeris 152b for positioning.

As illustrated in FIG. 4, the terminal 20 stores an observable satellite calculation program 112 in the first storage unit 110. The observable satellite calculation program 112 is a program for the control unit 100 to calculate the observable GPS satellites 12a and the like with reference to the initial position Q0 indicated by the initial position information 154.
Specifically, the control unit 100 refers to the almanac 152a to determine the GPS satellites 12a and the like that can be observed at the current time measured by the time measuring unit 104. The initial position Q0 is, for example, the previous positioning position.
The control unit 100 stores observable satellite information 156 indicating the observable GPS satellites 12 a and the like in the second storage unit 150.

  As illustrated in FIG. 4, the terminal 20 stores a measurement calculation program 114 in the first storage unit 110. The measurement calculation program 114 is a program for the control unit 100 to calculate a measurement including the code phase, IF frequency, Pmax, and Pnoise based on the coherent result. A measurement is an example of basic information. The measurement calculation program 114 and the control unit 100 are an example of basic information calculation means.

FIG. 5 is an explanatory diagram of the measurement calculation program 114.
In the baseband unit 32b, for example, coherent is performed with a width of 0.1 chip, and the maximum correlation value Pmax is output.
The baseband unit 32b calculates a code phase CPt corresponding to the maximum correlation value Pmax. The code phase is the phase of the C / A code when coherent is performed. The code phase is an example of a phase. Note that “when coherent is performed” is used synonymously with “when a C / A code is received”.
Further, the baseband unit 32b outputs the larger one of the correlation values of the phase shifted by ½ chip from the phase CPt as Pnoise. The terminal 20 regards Pnoise as a noise floor correlation value.
Pmax and Pnoise are examples of signal strength.
The IF frequency Ft is an IF frequency when coherent is performed. The IF frequency is an example of a reception frequency.

As illustrated in FIG. 4, the terminal 20 stores a measurement storage program 116 in the first storage unit 110. The measurement storage program 116 is a program for the control unit 100 to sequentially store the generated measurements in the measurement database 158 during a predetermined incoherent time. The incoherent time is, for example, 1 second.
The measurement database 158 is an example of a storage unit. The measurement storage program 116 and the control unit 100 are examples of basic information storage means.

FIG. 6 is a diagram illustrating an example of the measurement database 158.
As illustrated in FIG. 6, the control unit 100 stores, for example, the code phase CPt, the IF frequency Ft, Pmax, and Pnoise in the order calculated.
The measurement calculation interval is equal to the coherent time, and is, for example, 20 milliseconds (ms).
In the measurement database 158, for example, a measurement calculated during 1 second (s), which is an incoherent time, is stored.

  As illustrated in FIG. 4, the terminal 20 stores a reliability calculation program 118 in the first storage unit 110. The reliability calculation program 118 is a program for the control unit 100 to calculate the reliability Rt based on the Pmax integrated value B and the difference integrated value A. The reliability Rt is an example of reliability. The reliability calculation program 118 and the control unit 100 are examples of reliability calculation means.

FIG. 7 is an explanatory diagram of the reliability calculation program 118.
From the burst band unit 32b (see FIG. 3), PmaxB and signal strength difference A are output every time one coherent operation is completed.
PmaxB is Pmax for each coherent. For example, PmaxB at time t is 100, and the signal strength difference A is 20.
In this case, the reliability Rt is 0.2.

The control unit 100 calculates the reliability Rt by dividing the difference integrated value A by the Pmax integrated value B. The control unit 100 calculates the reliability Rt each time the Pmax integrated value B and the difference integrated value A are output from the baseband unit 32b.
The control unit 100 stores reliability information 160 indicating the reliability Rt in the second storage unit 150.

  As illustrated in FIG. 4, the terminal 20 stores a code phase prediction program 120 in the first storage unit 110. The code phase prediction program 120 is a program for the control unit 100 to calculate the prediction code phase PCP at the current time based on all the code phases stored in the measurement database 158. The prediction code phase PCP is an example of a prediction phase. The code phase prediction program 120 and the control unit 100 are an example of a predicted phase calculation unit.

FIG. 8 is an explanatory diagram of the code phase prediction program 120.
The control unit 100 calculates the predicted phase PCP at the current time t according to Equation 1 in FIG.
As shown in FIG. 8B, it is known that a graph G1 can be drawn for each frequency of one GPS satellite. For example, since the actual reception frequency varies with the movement of the GPS satellite 12a, if the IF frequency generated on the terminal 20 side is fixed, a difference occurs between the actual frequency and the IF frequency on the terminal 20 side. Reflect in the correlation value. The difference between the actual frequency and the IF frequency on the terminal 20 side is due to the Doppler shift due to the movement of the GPS satellite 12a. This means that the code phase CPt at time t after a certain time dt has elapsed can be predicted by Doppler shift. The Doppler shift is calculated based on the actual reception frequency. Since the transmission frequency from the GPS satellite 12a or the like is known, the Doppler shift can be calculated if the actual reception frequency is known.
For this reason, the predicted phase PCP at the current time t can be calculated by Equation 1. In Equation 1, F is a function indicating the relationship between the Doppler shift and the code phase. In Equation 1, the predicted phase PCP and the phase CP ( _t-dt ) at time t-dt are converted into distances.
The function F is a function for converting the Doppler shift into a relative movement speed. The radio waves S1 and the like propagate at the speed of light (3 × 10 ⁸ m / s). For this reason, the speed corresponding to the Doppler shift of 1 Hertz (Hz) can be calculated by dividing the speed of light by the transmission frequency of the radio wave S1 or the like. The transmission frequency is known, for example, 1,575.42 MHz. That the Doppler shift is plus (+) 1 hertz (Hz) means that the GPS satellite 12a is approaching the terminal 20 at a speed of 0.19 meters per second (m / s). The control unit 100 converts, for example, a plus (+) 1 Hertz (Hz) Doppler shift into a relative moving speed of 0.19 meters per second (m / s) by the function F as described above.
Equation 1 is satisfied under the condition that the elapsed time from the previous positioning is short.
Also, unlike the present embodiment, the average value of the Doppler shift at time t-dt and the Doppler shift at the current time may be used as the Doppler shift used in Equation 1. Thereby, the predicted phase PCP can be calculated more accurately.
The control unit 100 calculates the predicted phase PCP based on all the code phases stored in the measurement database 158. Specifically, control unit 100 calculates PCP1 based on code phase CP1 at time t1. Similarly, the control unit 100 calculates PCP2 to PCP15 based on the code phases CP2 to CP15 at times t2 to t15, respectively.
The control unit 100 stores the prediction code phase information 162 indicating the prediction code phase PCP in the second storage unit 150.
Unlike the present embodiment, the predicted phase PCP is not calculated based on all the code phases of the measurement database 158, but is calculated based on a predetermined number of new code phases, for example. You may make it do.

As illustrated in FIG. 4, the terminal 20 stores a code phase evaluation program 122 in the first storage unit 110. The code phase evaluation program 122 is a program for the control unit 100 to determine whether or not to use each predicted phase PCP for correcting the actual phase CPt at the current time t based on the actual phase CPt at the current time. is there. The code phase evaluation program 122 and the control unit 100 are an example of a predicted phase evaluation unit.
Specifically, the control unit 100 converts the difference between the measured phase CPt and each predicted phase PCP into a distance, and if the difference is within, for example, 45 meters (m), the predicted phase PCP is converted to the measured phase. Decide to use for correction of CPt.
If the measured phase CPt cannot be calculated at the current time t, the control unit 100 predicts the measured phase CPt using the measured phase CP _t−1 calculated before the current time t, and measures the measured phase CPt. An alternative to CP. At this time, the above Equation 1 is used. Here, as an actual reception frequency, a corrected frequency shown in corrected frequency information 168 described later is used. Since the accuracy of the Doppler shift is improved by using the corrected frequency, the accuracy of the predicted value of the actually measured phase CPt is also improved.
In this case, the control unit 100 calculates the predicted phase PCP using the measured phase CP _t-2 or the like before the measured phase CP _t-1 immediately before the current time t.

As illustrated in FIG. 4, the terminal 20 stores a code phase correction program 124 in the first storage unit 110. Code phase correction program 124, the control unit 100, based on the predicted phase PCP, to correct the measured code phase CP _t at the current time, a program for calculating the corrected code phase FCP _t. Corrected code phase FCP _{t is} an example of a corrected phase. The code phase correction program 124 and the control unit 100 are examples of actually measured phase correction means.

FIG. 9 is an explanatory diagram of the code phase correction program 124.
The control unit 100 calculates the corrected code phase FCP _{t according} to Equation 2 shown in FIG.
As shown in Equation 2, the control unit 100, by the actual code phase CP _t and the predicted phase PCP predetermined gain alpha, a weighted average. The gain α is, for example, 0.5.
As shown in FIG. 9B, the expression shown in Expression 2 means that the measured phase CP _t is corrected with all the predicted phases PCP. Here, the predicted phase PCP for correcting the measured phase CP _t is the predicted phase PCP determined to be used for correcting the measured phase CP _t by the code phase evaluation program 122 described above.
The control unit 100 stores the corrected code phase information 170 indicating the corrected code phase FCP _t in the second storage unit 150.

As illustrated in FIG. 4, the terminal 20 stores a reliability correction program 126 in the first storage unit 110. Reliability correction program 126, the control unit 100, a reliability _{R t} at the current time, by Pmax and Poise such actual code phase _{CP t-1} corresponding to the predicted phase PCP was used to correct the measured code phase CP _t This is a program for correcting.

FIG. 10 is an explanatory diagram of the reliability correction program 126.
The reliability R _{t at the} current time t1 is 0.2.
This reliability R _t is corrected by Pmax and Poise such as the actual measurement code phase CP _t−1 .
In FIG. 10, the Pmax integrated value C is an integrated value of Pmax such as each measured code phase CPt.
The difference integrated value D is an integrated value of the signal intensity difference A (see FIG. 7) such as each measured code phase CPt.
For example, when the reliability R _t is corrected by Pmax and Poise of the actual measurement code phase CP _{t−1 and the} like at time t2, Pmax at time t1 and Pmax at time t2 are integrated to obtain 200 as a Pmax integrated value C. . Then, 45 is obtained by integrating 20 at time t1 and 25 at time t2 as the difference integrated value D.
Then, 0.22 is obtained as the post-correction reliability FR _t .
In this manner, the control unit 100 calculates the post-correction reliability FR _t by sequentially using Pmax and Poise corresponding to the predicted phase PCP used for correcting the actual measurement code phase CP _t .
The control unit 100 stores corrected reliability information 166 indicating the corrected reliability FR _t in the second storage unit 150.

As illustrated in FIG. 4, the terminal 20 stores a frequency correction program 128 in the first storage unit 110. Frequency correction program 128, the control unit 100 is a an IF frequency at the current time, a program for correcting the IF frequency corresponding to the predicted phase PCP was used to correct the measured code phase CP _t.
More specifically, the control unit 100 calculates the IF frequency at the present time, the average value of the corresponding IF frequency predicted phase PCP was used to correct the measured code phase CP _t, and the corrected frequency.
The control unit 100 stores corrected frequency information 168 indicating the corrected frequency in the second storage unit 150.

As illustrated in FIG. 4, the terminal 20 stores a reliability evaluation program 130 in the first storage unit 110. The reliability evaluation program 130 is a program for the control unit 100 to evaluate the corrected reliability FR _t . The reliability evaluation program 130 and the control unit 100 are examples of reliability evaluation means.
Specifically, the control unit 100 determines whether or not the corrected reliability FR _t is 0.4 or more.

  As illustrated in FIG. 4, the terminal 20 stores a positioning program 132 in the first storage unit 110. The positioning program 132 is a program for the control unit 100 to perform positioning of the current position in the middle of incoherent based on the evaluation result by the reliability evaluation program 130 described above. The positioning program 132 and the control unit 100 are an example of incoherent midway positioning means.

FIG. 11 is a conceptual diagram showing a positioning method.
As shown in FIG. 11, for example, it can be considered that n C / A codes are continuously arranged between the GPS satellite 12 a and the terminal 20. Since the distance between the GPS satellite 12a and the terminal 20 is not necessarily an integer multiple of the length of the C / A code, there is a code fraction C / Aa. That is, between the GPS satellite 12a and the terminal 20, there are a part that is an integral multiple of the C / A code and a fractional part. The total length of the integral multiple of the C / A code and the fractional part is the pseudorange. The terminal 20 performs positioning using this pseudo distance.
The position of the GPS satellite 12a in the orbit can be calculated using the ephemeris 152b. Then, by calculating the distance between the position of the GPS satellite 12a in the orbit and the initial position Q0, a portion that is an integral multiple of the C / A code can be specified.
Then, as shown in FIG. 11, the correlation processing is performed while moving the phase of the replica C / A code in the direction of the arrow X1, for example.
The phase with the maximum correlation value is the code fraction C / Aa. The code fraction C / Aa is the corrected code phase FCP _t .

The control unit 100 calculates a pseudo distance between each GPS satellite 12a and the terminal 20 based on the corrected code phase FCP _t corresponding to three or more GPS satellites 12a and the like. Then, the position of each GPS satellite 12a or the like in the orbit is calculated by the epheris 152b. Then, based on the positions of the three or more GPS satellites 12a or the like in the orbit and the pseudo distance, the current position is measured and the positioning position Q1 is calculated.
The control unit 100 stores positioning position information 172 indicating the positioning position Q1 in the second storage unit 150.

  As illustrated in FIG. 4, the terminal 20 stores a positioning position output program 134 in the first storage unit 110. The positioning position output program 134 is a program for the control unit 100 to display the positioning position Q1 on the display device 34.

The terminal 20 is configured as described above.
The terminal 20 can measure the current position by the above positioning program 132 even in the middle of incoherence.
That is, if the corrected reliability FR _t is sufficient, the terminal 20 can perform positioning even in the middle of incoherence.
Thereby, even in the middle of incoherence, the current position can be measured with high accuracy.
Further, since the terminal 20 can correct the actual measurement code phase CPt at the current time by the prediction code phase PCP, the terminal 20 can perform positioning more accurately even during incoherence.
Further, if the measured phase CPt cannot be calculated at the current time t, the terminal 20 predicts the measured phase CPt using the immediately preceding measured phase CP _t−1 and replaces the measured phase CPt. can do. Then, the terminal 20 can calculate the predicted phase PCP using the measured phase CP _t-2 before the measured phase CP _t-1 immediately before the current time t. Thereby, even if it is a case where actual measurement phase CPt cannot be calculated in the present time, positioning can be performed in the middle of incoherent.
Furthermore, since the terminal 20 can calculate the predicted phase PCP at the current time based on all the code phases stored in the measurement database 158, the terminal 20 can calculate the current time based on as many predicted phases PCP as possible. Therefore, the accuracy of the corrected code phase FCP is improved.
Here, since all the code phases are selected in advance according to the deviation distance from the actually measured phase CPt, the accuracy of the corrected code phase FCP is further improved.
Hereinafter, the operation of the terminal 20 will be described in summary with reference to FIG.

FIG. 12 is a diagram illustrating incoherent time and the like.
As shown in FIG. 12A, the terminal 20 performs coherent for 20 milliseconds, for example, and determines the incoherent time as 1 second.
And when 1 second which is incoherent time passes, the reliability R is sufficiently over the threshold value 0.4 as shown, for example in FIG.12 (b).
However, the reliability R may exceed 0.4 as shown in FIG. 12C, for example, even at a time before 1 second, which is the incoherent time, has elapsed.
In this case, the terminal 20 starts positioning without waiting for the incoherent time to elapse.

The above is the configuration of the terminal 20 according to the present embodiment. Hereinafter, an example of the operation will be described mainly using FIGS. 13 and 14.
13 and 14 are schematic flowcharts showing an operation example of the terminal 20.

First, the terminal 20 calculates a measurement (step ST1 in FIG. 13). This step ST1 is an example of a basic information calculation step.
Subsequently, the terminal 20 calculates the prediction code phase PCP at the current time t for all the code phases CP in the measurement database 158 (step ST2).

Subsequently, the terminal 20 determines whether or not the difference between the actual measurement code phase CPt and each prediction code phase PCP is within 45 meters (step ST3).
Subsequently, in step ST3, the terminal 20 determines that the difference between the actual measurement code phase CPt and the prediction code phase PCP is within 45 meters.
Is used to correct the actual measurement code phase CPt (step ST4).
On the other hand, in step ST3, the terminal 20 does not use the prediction code phase PCP for which the difference between the actual measurement code phase CPt and the prediction code phase PCP is determined to be within 45 meters for correcting the actual measurement code phase CPt. Determine (step ST4A).

Subsequently, the terminal 20 calculates the corrected code phase FCP _t based on the predicted code phase PCP determined that the difference between the actual code phase CPt and the predicted code phase PCP is within 45 meters (step in FIG. 14). ST5).

Subsequently, the terminal 20 calculates a corrected frequency (step ST6).
Subsequently, the terminal 20 calculates a corrected reliability FR _t (step ST7).
Subsequently, the terminal 20 determines whether or not the corrected reliability FR _t is larger than the threshold value α (step ST8). This step ST8 is an example of a reliability evaluation step.

In step ST8, when the terminal 20 determines that the corrected reliability FR _t is larger than the threshold value α, positioning is performed (step ST9). This step ST9 is an example of an incoherent midway positioning step.
Subsequently, the terminal 20 outputs the positioning position Q1 (step ST10).

  With the above-described steps, the current position can be measured with high accuracy even in the middle of incoherence.

  The present invention is not limited to the embodiments described above. Furthermore, the above-described embodiments may be combined with each other.

It is the schematic which shows the terminal etc. of embodiment of this invention. It is the schematic which shows the main hardware constitutions of a terminal. It is the schematic which shows the structure of a GPS apparatus. It is the schematic which shows the main software structures of a terminal. It is explanatory drawing of a measurement calculation program. It is a figure which shows an example of a measurement database. It is explanatory drawing of a reliability calculation program. It is explanatory drawing of a code phase prediction program. It is explanatory drawing of a code phase correction program. It is explanatory drawing of a reliability correction program. It is a conceptual diagram which shows an example of a positioning method. It is the schematic which shows incoherent time etc. It is a schematic flowchart which shows the operation example of a terminal. It is a schematic flowchart which shows the operation example of a terminal.

Explanation of symbols

  12a, 12b, 12c, 12d ... GPS satellite, 20 ... terminal, 32 ... GPS device, 112 ... observable satellite calculation program, 114 ... measurement calculation program, 116 ... measurement storage Program 118 118 Reliability calculation program 120 Code phase prediction program 122 Code phase evaluation program 124 Code phase correction program 126 Reliability correction program 128 -Frequency correction program, 130 ... Reliability evaluation program, 132 ... Positioning program, 134 ... Positioning position output program

Claims (10)

A positioning device that receives a positioning basic code from a transmission source, performs a correlation process including coherent and incoherent, and positions a current position,
Basic information calculating means for calculating basic information including the phase of the positioning basic code and the signal strength of the positioning basic code;
Reliability calculation means for calculating the reliability of the phase based on the signal intensity;
A reliability evaluation means for evaluating the reliability;
Based on the evaluation result of the reliability evaluation means, in the middle of the incoherent, incoherent midway positioning means for positioning the current position,
A positioning device comprising: Basic information storage means for storing the basic information in a storage means each time the basic information is generated;
A predicted phase calculating means for calculating a predicted phase at the current time based on the phase stored in the storage means;
Based on the predicted phase, the phase correction means for correcting the phase at the current time and calculating a corrected phase;
The positioning device according to claim 1, comprising: The basic information includes a reception frequency when the positioning basic code is received,
The predicted phase calculation means is configured to predict the phase at the current time based on the phase calculated before the current time and the reception frequency when the phase cannot be calculated at the current time. The positioning device according to claim 1, wherein the positioning device is provided.   4. The prediction phase calculation unit is configured to calculate a prediction phase at a current time based on all the phases stored in the storage unit. A positioning device according to the above.   A prediction phase evaluation unit that determines whether or not the prediction phase is used for correcting the phase at the current time depending on whether or not the deviation from the phase at the current time is within a predetermined allowable range; The positioning device according to any one of claims 2 to 4. The predicted phase calculation means is configured to calculate the predicted phase using an expression of “predicted CP _t = CP _(t−dt) + F (Doppler _(t−dt) ) × dt”. The positioning device according to claim 2, wherein the positioning device is characterized.   The positioning device according to claim 1, wherein the transmission source is a positioning satellite including a GPS (Global Positioning System) satellite. A positioning device that receives a positioning basic code from a transmission source, performs a correlation process including coherent and incoherent, and measures a current position includes a phase of the positioning basic code and a signal strength of the positioning basic code A basic information calculating step for calculating basic information;
A reliability evaluation step in which the positioning device evaluates the reliability of the corrected phase based on the signal strength;
The positioning device, based on the evaluation result of the reliability evaluation means, in the middle of the incoherent, incoherent midway positioning step for positioning the current position,
A method for controlling a positioning device, comprising: On the computer,
A positioning device that receives a positioning basic code from a transmission source, performs a correlation process including coherent and incoherent, and measures a current position includes a phase of the positioning basic code and a signal strength of the positioning basic code A basic information calculating step for calculating basic information;
A reliability evaluation step in which the positioning device evaluates the reliability of the corrected phase based on the signal strength;
The positioning device, based on the evaluation result of the reliability evaluation means, in the middle of the incoherent, incoherent midway positioning step for positioning the current position,
A control program for a positioning device, characterized in that On the computer,
A positioning device that receives a positioning basic code from a transmission source, performs a correlation process including coherent and incoherent, and measures a current position includes a phase of the positioning basic code and a signal strength of the positioning basic code A basic information calculating step for calculating basic information;
A reliability evaluation step in which the positioning device evaluates the reliability of the corrected phase based on the signal strength;
The positioning device, based on the evaluation result of the reliability evaluation means, in the middle of the incoherent, incoherent midway positioning step for positioning the current position,
The computer-readable recording medium which recorded the control program of the positioning apparatus characterized by performing these.

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