JP4797574B2 - Positioning device, positioning calculator and positioning calculation method - Google Patents

Description

  The present invention relates to a positioning device, a positioning calculator, and a positioning calculation method in a satellite navigation system.

In a GPS (Global Positioning System) that measures the position of a positioning device using a positioning satellite, the positioning device measures the radio wave propagation time between the positioning satellite and the positioning device, and calculates the distance by multiplying the radio wave propagation time by the speed of light. The position is measured by using the distance information measured and the position information of the GPS satellite. The radio wave propagation time is measured using a clock provided in the positioning device and synchronized with the atomic clock of the positioning satellite. For this reason, an extremely stable clock is required for the timepiece in the positioning device. In applications that require high positioning accuracy, a TCXO (Temperature Compensated Xtal Oscillator) having a compensation circuit that compensates for fluctuations in oscillation frequency due to temperature is used as the internal clock of the positioning device (for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-133553 (page 4, FIG. 4)

However, since TCXO is expensive, it is desirable to apply XO (Xtal Oscillator) without a temperature compensation circuit to the positioning device in terms of cost. However, a positioning device using an inexpensive clock such as XO has the following problems.
First, since XO has a large clock error and poor stability, there has been a problem that positioning calculation that requires accurate time information causes a large error in positioning.
Further, XO prevents the increase of the clock error by forcibly resetting the clock when the accumulated clock error exceeds a certain value, but there is a problem that the positioning result becomes discontinuous with the occurrence of the clock reset.

The present invention has been made to solve such a problem, and an object of the present invention is to easily obtain a highly accurate positioning result even in a positioning apparatus using an inexpensive clock such as XO as an internal clock.
Another object of the present invention is to prevent discontinuity in the positioning result even when the clock is reset by the XO.

A positioning apparatus according to the present invention is a positioning apparatus that includes a signal receiving unit that receives a positioning signal from a positioning satellite, calculates a pseudo distance based on the positioning signal, and a positioning calculation unit that performs a positioning calculation using the pseudo distance. The signal receiving unit has an XO (Xtal Oscillator) as an internal clock, and performs clock reset when the clock error of the XO exceeds a predetermined value with respect to a reference clock used by the positioning satellite. A clock reset function for preventing an increase, and when the positioning calculation unit detects that the clock reset has been executed, a difference- converted clock before the clock reset is detected by calculating a difference between the pseudo distances before and after the clock reset is detected. and offset correction to the error and distance conversion clock error after the clock reset detection, those Positioning calculation is performed using the distance-converted clock error after the offset correction.

In a satellite navigation system that measures the position of a positioning device using a positioning satellite such as GPS, even a positioning device that applies an inexpensive clock such as XO to the internal clock can easily obtain highly accurate positioning results. Obtainable.
In addition, it is possible to prevent discontinuity in the positioning result even when the clock is reset for the synchronization of XO.

In addition to GPS, satellite navigation systems that measure the position of a positioning device using positioning satellites include Glonus (GLONASS, Global Navigation Satellite System), Galileo, and the like. In the following first to seventh embodiments, GPS will be described as an example of a satellite navigation system.
Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a positioning device 100 according to the first embodiment.
In FIG. 1, the positioning device 100 includes a positioning signal receiving unit 200 and a positioning calculation unit 300.
A positioning signal receiving unit (hereinafter referred to as a signal receiving unit) 200 receives a positioning radio signal (hereinafter referred to as a positioning signal) 10 from a plurality of GPS satellites.
The GPS satellite 1 transmits a C / A (Clear and Acquisition) code and a navigation message on a carrier wave of 1,575.42 MHz (L1 band). The navigation message includes parameters for correcting the ionosphere, correction values for the on-board clock, and the like in addition to satellite orbit-related information necessary for positioning calculation and the like.

The signal receiving unit 200 obtains positioning information 295 based on the received positioning signal 10. Here, the positioning information 295 refers to pseudo distance, carrier phase, Doppler, signal strength (S / N), data reception time, and navigation message. The signal receiving unit 200 outputs the positioning information 295 to the positioning calculation unit 300.
Here, as will be described later, the data reception time is a time output by a clock provided in the signal receiving unit 200, and means a time when the signal receiving unit 200 receives the positioning signal 10 from a GPS satellite.

  The positioning calculation unit 300 performs a positioning calculation using the positioning information 295 and outputs a positioning calculation result 395. Here, the positioning calculation result 395 refers to the position of the positioning device (latitude, longitude, altitude) obtained by the positioning calculation and the clock error of the clock mounted on the signal receiving unit 200. The clock error means a time lag between the time of the clock mounted on the signal receiving unit 200 and the time of the reference clock mounted on the GPS satellite.

FIG. 2 is a configuration diagram of the signal receiving unit 200.
In FIG. 2, the signal receiving unit 200 includes a positioning signal receiving antenna 205, an RF (Radio Frequency) front-end processing unit 220, an A / D (Analog / Digital) conversion unit 230, and a baseband chip processing unit 260.
The RF front end processing unit 220 includes an XO 221 that is a watch mounted on the positioning device 100.

Next, the operation of the signal receiving unit 200 will be described with reference to FIG.
The positioning signal receiving antenna 205 receives the positioning signal 10 from at least four or more GPS satellites 1.
The XO 221 generates a reference signal of about 20 MHz, for example.
The RF front-end processing unit 220 performs high-frequency analog processing on the received positioning signal 10. Specifically, since it is difficult to directly digitally process the positioning signal 10 having a frequency of 1,575.42 MHz, the frequency of the positioning signal 10 is set to 2 MHz by performing the mixing process a plurality of times using the reference signal generated by the XO 221. Processing to drop to about 10 MHz.
The A / D conversion unit 230 converts the positioning signal 10 processed by the RF front end processing unit 220 from an analog signal to a digital signal.
The baseband chip processing unit 260 performs spectrum despreading on the digitally converted positioning signal 10. By performing the spectrum despreading, the carrier wave before the spectrum spread is extracted from the positioning signal 10 transmitted by the spectrum spread by the GPS satellite. Then, the phase difference between the carrier wave extracted by performing spectrum despreading and the reference signal generated by the XO 221 is detected.

  The baseband chip processing unit 260 obtains the positioning signal propagation time from the detected phase difference. Then, the pseudo distance between the GPS satellite that has transmitted the positioning signal and the signal receiving unit 200 is calculated by multiplying the obtained propagation time of the positioning signal by the speed of light.

Based on the received positioning signal 10, the baseband chip processing unit 260 obtains information such as pseudorange, navigation message, data reception time, carrier phase, Doppler, signal strength (S / N), and the like. The baseband chip processing unit 260 outputs the positioning information 295 to the positioning calculation unit 300.

In the present invention, a positioning calculation unit 300 is provided outside the signal receiving unit 200, and the positioning calculation unit 300 inputs positioning information 295 to perform positioning calculation.

FIG. 29 to FIG. 32 show an example of the positioning result in the conventional positioning device.
FIG. 29 is an example of the data reception time t output by the signal reception unit 200. GPS employs a time system called GPS time, which is the time engraved by the atomic clock of the GPS satellite and is the number of seconds since the beginning of the week.

The data reception time is a time that is output based on the second signal generated by the XO 221 synchronized with the atomic clock of the GPS satellite 1 included in the signal reception unit 200 at the GPS time, and the signal reception unit 200 performs positioning from the GPS satellite. The time when the signal 10 is received.

FIG. 30 shows an example of the clock error δ obtained by the positioning calculation described later. The clock error σ indicates a time lag between the time of the XO 221 and the time of the reference clock mounted on the GPS satellite.
In the example of the clock error δ shown in FIG. 30, the clock error δ increases with the passage of time, and shows a saw-like characteristic in which the value changes discontinuously from the plus side to the minus side at a certain time. As described above, the discontinuity in the clock error δ is caused by the fact that the clock error of the XO 221 which is the internal clock of the positioning device 100 is large, and the clock error accumulated after the positioning is started becomes equal to or greater than a certain value. This is a result of the signal receiving unit 200 forcibly resetting the clock at the time when synchronization with the clock is lost and trying to synchronize with the atomic clock in the GPS satellite again.

  As described above, the data reception time t output from the signal receiving unit 200 includes the clock error δ due to the accuracy of the clock XO in the signal receiving unit 200. When the clock error is integrated and exceeds a certain value, a clock reset occurs, and as a result, a discontinuity also occurs at the data reception time t.

  FIG. 31 shows an example of a conventional positioning result. Positioning was performed by measuring a position where an accurate position was known in advance. The vertical axis represents the amount of error (Δlatitude, Δlongitude) in the latitude and longitude directions of the position obtained by the positioning calculation. The error amount has a tendency to correlate with a change in clock error. When the clock reset occurs, it shows a saw-like characteristic in which the error amount changes discontinuously and shows a tendency correlated with a change in clock error. As described above, the clock error has greatly influenced the positioning result.

FIG. 32 is a plot of positioning results for each elapsed time, where the vertical axis is Δlatitude and the horizontal axis is Δlongitude.
In the example of FIG. 32, an error of about −8 (m) at the maximum is shown (area indicated by a in FIG. 32). Further, the value of the error amount is discontinuously large when the clock reset occurs.

As described above, when the positioning calculation unit 300 is conventionally provided outside the signal receiving unit 200 and the positioning calculation unit 300 inputs the positioning information 295 and performs the positioning calculation, the positioning position output by the positioning calculation unit 300 is a large positioning. There was an error, and when the clock reset occurred, the positioning position was discontinuously large and the value changed.

FIG. 3 is an example of a configuration diagram of the positioning calculation unit 300 according to the first embodiment.
The positioning calculation unit 300 includes a time correction unit 340, a satellite position calculation unit 370, a pseudo distance correction unit 380, a positioning calculation unit 390, a determination unit 392, and a control unit 301 that controls the operation of the entire positioning calculation unit. In addition, a pseudo distance correction value receiving unit 382 connected to the pseudo distance correcting unit 380 is provided, and the pseudo distance correcting unit 380 acquires correction information from the outside through a communication line, and corrects the pseudo distance using the correction information. Good.
FIG. 4 is a diagram illustrating an operation flow of the positioning calculation unit 300.

  Next, the operation of the positioning calculation unit 300 in the first embodiment will be described with reference to FIGS. 3 and 4.

  (1) First, the positioning calculation unit 300 receives the positioning information 295 from the signal receiving unit 200 (step S101 in FIG. 4, hereinafter referred to as S101).

(2) Next, the satellite position calculation unit 370 calculates the satellite position of the GPS satellite (S102). The satellite position is calculated by a known method using orbit information (ephemeris) included in the navigation message.

Here, the trajectory information is as follows.
toe: reference time of orbital element M0: average near point separation angle at toe e: eccentricity A: orbital radius Ω0: ascending intersection red
i0: Orbital tilt angle ω: Peripheral arguments e and A define the shape of an ellipse, and M0 defines the position of the satellite at a certain moment above it. Ω0, i0, and ω define the orientation of this orbital plane in space.
The position (Xs _i (t), Ys _i (t), Zs _i (t)) of the GPS satellite i at time t is expressed as follows using t, toe, M0, e, A, Ω0, i0, ω as parameters. Can be calculated as follows.

(Xs _i (t), Ys _i (t), Zs _i (t)) = f (t, toe, M0, e, A, Ω0, i0, ω)
Here, f is a predetermined function. The calculation of the satellite position is described in, for example, Navstar GPS Space Segment / Navigation User Interfaces, Interface Control Document, ICD-GPS-200, rev. C, Oct. 1993.

Here, the process of calculating the position of the GPS satellite using the orbit information (ephemeris) is shown in FIG. The satellite position calculation unit 370 receives the positioning information 295 from the signal reception unit 200. The positioning information 295 includes a data reception time t when the signal receiving unit 200 receives data from a plurality of GPS satellites (i, j, k,...), A pseudorange PR for each GPS satellite, a carrier phase, a navigation message, and the like. It is. By dividing the pseudo-range PR for each GPS satellite by the speed of light c, the radio wave propagation time of the radio wave transmitted by the GPS satellite can be calculated. By subtracting the calculated radio wave propagation time from the data reception time t, The transmission time can be calculated.
On the other hand, the orbit information of each GPS satellite can be acquired from the navigation message.
As described above, the satellite position calculation unit 370 calculates the satellite position of the GPS satellite by using the calculated time when the GPS satellite transmits the radio wave and the orbit information of the GPS satellite.

(3) The pseudorange correction unit 380 corrects the pseudorange PR received from the signal receiving unit 200 based on the information regarding the ionosphere delay and the troposphere delay in the navigation message (S103).
(4) Next, the positioning calculation unit 390 performs positioning calculation and calculates the position (Xgps, Ygps, Zgps) of the positioning device 100 (S104). Specifically, the position (Xgps, Ygps, Zgps) of the positioning device is calculated by solving simultaneous equations of the following equations (1a) to (4a). More specifically, the position of the positioning device is the position of the signal receiving unit 200.

PR ₁ (t) = √ {(Xs ₁ (t) −Xgps) ² + (Ys ₁ (t) −Ygps) ² + (Zs ₁ (t) −Zgps) ² } + ΔS (t) Equation (1a)
PR ₂ (t) = √ {(Xs ₂ (t) −Xgps) ² + (Ys ₂ (t) −Ygps) ² + (Zs ₂ (t) −Zgps) ² } + ΔS (t) Equation (2a)
PR ₃ (t) = √ {(Xs ₃ (t) −Xgps) ² + (Ys ₃ (t) −Ygps) ² + (Zs ₃ (t) −Zgps) ² } + ΔS (t) Equation (3a)
PR ₄ (t) = √ {(Xs ₄ (t) −Xgps) ² + (Ys ₄ (t) −Ygps) ² + (Zs ₄ (t) −Zgps) ² } + ΔS (t) Equation (4a)

Here, PR _i (t) (GPS satellite number i = 1 to 4) is a pseudo distance between the GPS satellite i and the positioning device 100 obtained based on the positioning information 295 at the data reception time t. Xs _i (t), Ys _i (t), and Zs _i (t) (GPS satellite numbers i = 1 to 4) respectively indicate the X coordinate position, the Y coordinate position, and the Z coordinate position of the GPS satellite i. ΔS (t) is a distance-converted clock error obtained by converting the clock error δ, which is time information, into a distance. The clock error obtained based on the positioning information 295 at the data reception time t is δ (t), and the speed of light is c. Then, it can be expressed as ΔS (t) = c · δ (t).

  The simultaneous equations of equations (1a) to (4a) can be solved by, for example, the least square method. Here, by solving the simultaneous equations of the equations (1a) to (4a), the distance conversion clock error ΔS (t) is obtained together with the position of the positioning device (Xgps, Ygps, Zgps).

  (5) Next, the determination unit 392 determines whether the positioning calculation based on the positioning information 295 at the data reception time t is the first time or the second time (S105).

  (6) As a result of the determination, if it is the first positioning calculation based on the positioning information 295 at the data reception time t, the time correction unit 340 performs the time correction and the corrected reception time which is the corrected data reception time. tcal is obtained (S106).

Time correction is performed according to equation (5). That is, the corrected reception time tcal is the clock error δ () obtained by dividing the distance conversion clock error ΔS (t) obtained by the equations (1a) to (4a) from the data reception time t included in the positioning information 295 by the light speed c. This is done by subtracting t).

   tcal = t−ΔS (t) / c = t−δ (t) Equation (5)

  The time correction unit 340 outputs a corrected reception time tcal 396, which is a corrected data reception time, to the satellite position calculation unit 370.

  (7) Next, the satellite position calculation unit 370 calculates the satellite position (Xsi (t), Ysi (t), Zsi (t)) of each GPS satellite using the corrected reception time tcal (S106). . Similarly to step S102, the satellite position calculation unit 370 receives the corrected reception time tcal and uses the orbit information (ephemeris) to determine the satellite position (Xsi (tcal), Ysi (tcal), Zsi (tcal) at the corrected reception time tcal. )) (I = 1 to 4) are calculated and output to the positioning calculation unit 390.

(8) The positioning calculation unit 390 performs positioning calculation again using the corrected satellite position (Xsi (tcal), Ysi (tcal), Zsi (tcal)) (i = 1 to 4) (S102).
That is, the position (Xgps, Ygps, Zgps) of the positioning device is calculated by solving the following simultaneous equations (1b) to (4b).

PR ₁ (t) = √ {(Xs ₁ (tcal) −Xgps) ² + (Ys ₁ (tcal) −Ygps) ² + (Zs ₁ (tcal) −Zgps) ² } + ΔS (t) Equation (1b)
PR ₂ (t) = √ {(Xs ₂ (tcal) −Xgps) ² + (Ys ₂ (tcal) −Ygps) ² + (Zs ₂ (tcal) −Zgps) ² } + ΔS (t) Equation (2b)
PR ₃ (t) = √ {(Xs ₃ (tcal) −Xgps) ² + (Ys ₃ (tcal) −Ygps) ² + (Zs ₃ (tcal) −Zgps) ² } + ΔS (t) Equation (3b)
PR ₄ (t) = √ {(Xs ₄ (tcal) −Xgps) ² + (Ys ₄ (tcal) −Ygps) ² + (Zs ₄ (tcal) −Zgps) ² } + ΔS (t) Equation (4b)

  (9) Next, the determination unit 392 determines whether the positioning calculation by the positioning calculation unit 390 is the first time or the second time (S105).

  (10) In the case of the second positioning calculation, the determination unit 392 uses the position (Xgps, Ygps, Zgps) obtained by solving the simultaneous equations (1b) to (4b) as the position of the positioning device as text data. For example, data is serially output to a personal computer or the like (S107).

  (11) The control unit 301 determines whether or not to continue positioning (S108). If the positioning is continued, the control unit 301 returns to step S101 and receives the positioning information 295.

As described above, in the first embodiment of the present invention, first, the data reception time is calculated using the distance conversion clock error ΔS (t) obtained by solving the simultaneous equations expressed by the equations (1a) to (4a). t was corrected.
Next, the satellite position (Xs _i (tcal), Ys _i (tcal), Zs _i (tcal)) of each GPS satellite is calculated based on the corrected data reception time tcal.
Then, by solving the simultaneous equations (equations (1b) to (4b)) using the calculated satellite positions (Xs _i (tcal), Ys _i (tcal), Zs _i (tcal)), the position of the positioning device ( Xgps, Ygps, Zgps).

As described above, in the first embodiment, the positioning calculation is performed again using the satellite position calculated using the data reception time corrected based on the distance conversion clock error ΔS (t) obtained by the first positioning calculation. Therefore, even in a positioning device that applies an inexpensive clock such as XO to the internal clock, a highly accurate positioning result can be obtained easily.
Further, by providing the positioning calculation unit 300 that performs the positioning calculation by processing the positioning information 295 output from the signal receiving unit 200 outside the signal receiving unit 200, the calculation processing method can be easily changed and improved, and There is an effect that a positioning result with high accuracy can be easily obtained.

  Note that the positioning calculation unit 300 may be in the signal receiving unit 200, and the signal receiving unit 200 may output the positioning calculation result 395. Further, the signal receiving unit 200 may be in the positioning calculation unit 300, and the positioning calculation unit 300 may receive the positioning signal 10 from the positioning signal.

Embodiment 2. FIG.
In the first embodiment, in a positioning device using an inexpensive clock such as XO as an internal clock, the positioning calculation unit 390 always performs the second positioning calculation and outputs a positioning calculation result 395 for the purpose of improving accuracy. It was. In the second embodiment, the magnitude of the clock error δ (t) (= ΔS (t) / c) obtained in the first positioning calculation is determined. If the clock error δ (t) is small, the second time is calculated. The positioning calculation is not performed, and the first calculation result is output as the positioning calculation result 395.

  FIG. 3 shows a configuration of positioning calculation section 300 in the second embodiment. The configuration of the positioning calculation unit 300 is the same as that of the first embodiment.

  FIG. 6 is a diagram illustrating an operation flow of the positioning calculation unit 300 according to the second embodiment. In the second embodiment, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

Next, the operation of the positioning calculation unit 300 will be described with reference to FIGS. 3, 6, and 7.
(1) First, a clock error threshold δclock is set in the determination unit 392 as a reference value for determining the magnitude of the clock error δ (t) (S200). The clock error threshold δclock is set to 2 (milliseconds) as shown in FIG. 7, for example, but the set value may be changed according to the required positioning accuracy.

  (2) The positioning calculation unit 390 performs satellite position calculation (S102) and pseudorange correction (S103) based on the received positioning information 295, and the positioning calculation unit 390 determines the position of the positioning device (Xgps, Ygps, Zgps). ) And clock error δ (t) are calculated and output (S104).

(3) Next, the determination unit 392 compares the clock error δ (t) with the clock error threshold value δclock (S205).
(4) When the clock error δ (t) is larger than the clock error threshold δclock, it is determined that the error included in the positioning result is large, and time correction is performed in the same manner as in the first embodiment. A reception time tcal is obtained (S106).
(5) The satellite position calculation unit 370 calculates the satellite position (Xs _i (tcal), Ys _i (tcal), Zs _i (tcal)) (i = 1 to 4) at the inputted corrected reception time tcal. (S207).
(6) The positioning calculation unit 390 uses the satellite position calculated in S207 to build simultaneous equations of Formulas (1b) to (4b) and performs positioning calculation again (S208), and positioning results (Xgps, Ygps , Zgps) is output (S107).

  As described above, in the second embodiment, the clock error δ (t) calculated by the positioning calculation is compared with the preset clock error threshold δclock, and when the clock error δ (t) is small, the calculation result (Xgps, Ygps, Zgps) is determined to have a small error, and this result is output as a positioning calculation result 395.

In the second embodiment, when the clock error δ (t) obtained by the first positioning calculation is small, time correction is not performed and the second positioning calculation is omitted, so the load on the positioning calculation unit 390 is reduced. And the time until the positioning calculation result 395 is obtained is shortened.
Further, by providing the positioning calculation unit 300 that performs the positioning calculation by processing the positioning information 295 output from the signal receiving unit 200 outside the signal receiving unit 200, the calculation processing method can be easily changed and improved, and There is an effect that a positioning result with high accuracy can be easily obtained.

  Note that the positioning calculation unit 300 may be in the signal receiving unit 200, and the signal receiving unit 200 may output the positioning calculation result 395. Further, the signal receiving unit 200 may be in the positioning calculation unit 300, and the positioning calculation unit 300 may receive the positioning signal 10 from the positioning signal.

Embodiment 3 FIG.
In the second embodiment, the positioning time is shortened by omitting the second positioning calculation when the clock error δ (t) calculated by the positioning calculation unit 390 is small.
Here, a positioning interval at which the positioning device 100 receives the positioning signal 10 from the GPS satellite 1 and performs positioning is referred to as an epoch. One epoch is, for example, 1 (second). In the third embodiment, the clock error δ (t) in the current epoch is changed to the clock error δ (t−1) in the previous epoch or the clock error δ (t−2) in the second epoch. And the like, and the data reception time t is corrected using the estimated clock error δ (t) of the current epoch. By calculating the satellite position using the corrected data reception time tcal and performing the positioning calculation using the calculated satellite position, a highly accurate positioning result is obtained in real time with only one positioning calculation.

FIG. 8 is a configuration diagram of the positioning calculation unit 700 in the third embodiment.
The positioning calculation unit 700 is an overall operation of the time correction unit 340, the clock error time extrapolation unit 350, the clock drift calculation unit 360, the satellite position calculation unit 370, the pseudorange correction unit 380, the positioning calculation unit 390, and the positioning calculation unit 700. The control part 301 which controls this is provided. A pseudo distance correction value receiving unit 382 connected to the pseudo distance correcting unit 380 may be provided, and the pseudo distance correcting unit 380 may acquire correction information from the outside, and correct the pseudo distance using the correction information. In the third embodiment, the same or corresponding parts as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 9 is a diagram illustrating an operation flow of the positioning calculation unit 700 according to the third embodiment. FIG. 10 is a diagram showing a continuation of the operation flow of the positioning calculation unit 700 in the third embodiment. FIG. 11 is a diagram showing the data reception time t and the distance conversion clock error ΔS for explaining the operation flow of the positioning calculation unit 700. FIG. 12 is a diagram for explaining the data flow of the clock error.

Next, the operation of the positioning calculation unit 700 in the third embodiment will be described with reference to FIGS. 8 and 9 to 12.
(1) First, the control unit 301 initializes an epoch counter that counts the number of positioning times (S301). At the start of positioning, the epoch counter I is initialized as “0”.

(2) The positioning calculation unit 700 receives the positioning information 295 from the signal receiving unit 200 (S302).

(3) The control unit 301 determines whether or not the epoch counter I is less than 3 (S303).

(4) If the epoch counter I is less than 3, the control unit 301 adds 1 to the epoch counter I (S304).

(5) The control unit 301 determines whether or not the epoch counter I is 3 or more (S305). If it is not after the third epoch, the process proceeds to S320 in FIG.

(6) In S320 of FIG. 10, the control unit 301 determines whether or not it is the first epoch (S320).

(7) If it is the first epoch, the satellite position calculation unit 370 calculates the satellite position of the GPS satellite (S321). The satellite position calculation unit 370 inputs the data reception time t and based on the orbit information (ephemeris) given by the navigation message, the satellite position (Xs _i (t), Ys _i (t), Zs _i (t)) (GPS The satellite number i = 1 to 4) is calculated.

(8) The pseudorange correcting unit 380 corrects the pseudorange PR received from the signal receiving unit 200 based on the information regarding the ionospheric delay and the tropospheric delay included in the navigation message (S322). Here, when the pseudo distance correction value reception unit 382 is provided, the pseudo distance correction unit 380 may acquire correction information of DGPS (Differential GPS) and correct the pseudo distance.

(9) Next, the positioning calculation unit 390 performs positioning calculation and calculates the position (Xgps, Ygps, Zgps) of the positioning device 100 (S323). Specifically, the position of the positioning device (Xgps, Ygps, Zgps) is calculated by solving the simultaneous equations (1a) to (4a) as in the first embodiment. Here, by solving the simultaneous equations of the equations (1a) to (4a), the distance conversion clock error ΔS (t) is obtained together with the position of the positioning device. The positioning calculation unit 390 outputs the distance conversion clock error ΔS (t) to the clock drift calculation unit 360.

(10) The clock drift calculation unit 360 stores the inputted distance conversion clock error ΔS (t) as the distance conversion clock error ΔS−2 two epochs before (S324). Next, the process returns to S302.

(11) If it is the second epoch in the determination of S320, the positioning calculation unit 390 performs the satellite position calculation, the pseudorange correction, and the positioning calculation as in the first epoch (S325 to S327). The positioning calculation unit 390 outputs the distance conversion clock error ΔS to the clock drift calculation unit 360.

(12) The clock drift calculator 360 stores the input distance-converted clock error ΔS (t) as the distance-converted clock error ΔS−1 one epoch before (S328). Next, the process returns to S302.

(13) If it is after the third epoch in S305, the following is performed. The clock drift calculation unit 360 calculates a difference ΔSd between the distance converted clock error ΔS-1 before one epoch and the distance converted clock error ΔS-2 before two epochs (S306, see FIG. 11). The difference ΔSd is output to the clock error time extrapolation unit 350 (ΔSd = ΔS−1 ΔS−2).

(14) Next, the clock error time extrapolation unit 350 adds the distance converted clock error ΔS-1 one epoch before and the difference ΔSd obtained in S305 to estimate the distance converted clock error estimate ΔS in the current epoch. 'Is calculated (S307, see FIGS. 11 to 12). The calculated ΔS ′ is output to the time correction unit 340 (ΔS ′ = ΔS−1 + ΔSd).

(15) The time correction unit 340 obtains the estimated value ΔS ′ of the distance conversion clock error and corrects the time. The data reception time tgps is corrected by equation (7) to obtain a corrected data reception time tcal (S308). Here, c is the speed of light.
tcal = tgps−ΔS ′ / c Equation (7)
The time correction unit 340 outputs the corrected reception time tcal 396 to the satellite position calculation unit 370.

(16) Next, the satellite position calculation unit 370 determines the satellite position (Xs _i (t), Ys _i (t), Zs _i (t)) (i = 1) of each GPS satellite based on the corrected reception time tcal. ˜4) is calculated (S309). The satellite position calculation unit 370 obtains the corrected satellite position by giving the corrected reception time tcal to the orbit information (ephemeris) given by the navigation message. Thus, the satellite position (Xs _i (tcal), Ys _i (tcal), Zs _i (tcal)) (i = 1 to 4) at the corrected reception time tcal is acquired. The acquired satellite positions (Xs _i (tcal), Ys _i (tcal), Zs _i (tcal)) are output to the positioning calculation unit 390.

(17) The pseudo distance correcting unit 380 corrects the pseudo distance PR received from the signal receiving unit 200 based on information regarding ionospheric delay and tropospheric delay included in the navigation message of the positioning information 295 (S310). The corrected pseudo distance is output to the positioning calculation unit 390.

(18) Next, the positioning calculation unit 390 performs positioning calculation to calculate the position (Xgps, Ygps, Zgps) of the positioning device 100 (S311). Specifically, the satellite position (Xs _i (tcal), Ys _i (tcal), Zs _i (tcal)) input from the satellite position calculation unit 370 and the pseudo distance PRi (t ) Using (i = 1 to 4), the simultaneous equations of the expressions (1b) to (4b) in the first embodiment are established. Then, the position of the positioning device is calculated by solving the simultaneous equations.
Here, by solving the simultaneous equations of the equations (1b) to (4b), the distance conversion clock error ΔS is obtained together with the position of the positioning device (Xgps, Ygps, Zgps). The positioning calculation unit 390 outputs the distance conversion clock error ΔS to the clock drift calculation unit 360.

(19) Next, the clock drift calculation unit 360 stores the distance converted clock error ΔS-1 one epoch before in the distance converted clock error ΔS-2 two epochs before (S312; see FIG. 12).

(20) The clock drift calculation unit 360 stores the inputted distance conversion clock error ΔS (t) as the distance conversion clock error ΔS-1 one epoch before storing the data (S313, see FIG. 12).

(21) Next, return to S302 and continue positioning.

  As described above, in the third embodiment, the clock error ΔS in the current epoch is estimated by linear extrapolation using the clock error values one epoch and two epochs before, and the data reception time is estimated using the estimated clock error. Perform tgps time correction. Then, the satellite position is calculated based on the corrected data reception time, and the positioning calculation is performed based on the calculated satellite position and pseudorange.

As a result, even in a positioning device that applies an inexpensive clock such as XO to the internal clock, the clock error in the current epoch can be accurately estimated. As a result, a highly accurate positioning result can be easily obtained in real time. Obtainable.
Further, by providing the positioning calculation unit 700 that processes the positioning information 295 output from the signal receiving unit 200 and performs the positioning calculation outside the signal receiving unit 200, the calculation processing method can be easily changed and improved, and There is an effect that a positioning result with high accuracy can be easily obtained.

  In the third embodiment, the clock error is estimated by linear extrapolation using the clock error values before and after two epochs. However, the number of clock errors used for the estimation is not limited to two but three. Needless to say, the clock error may be estimated by a higher-order function.

  Note that the positioning calculation unit 700 may be in the signal receiving unit 200, and the signal receiving unit 200 may output the positioning calculation result 395. Further, the signal receiving unit 200 may be in the positioning calculation unit 300, and the positioning calculation unit 300 may receive the positioning signal 10 from the positioning signal.

Embodiment 4 FIG.
In the third embodiment, the clock error in the current epoch is estimated using the past clock error value, the time is corrected using the estimated clock error, and the positioning calculation in the current epoch is performed. In a positioning device that applies an inexpensive clock such as XO to the internal clock, when the clock error in the current epoch is estimated from the value of the past clock error in this way, a clock reset due to clock accuracy occurs. At the time of reset, there is a large difference between the estimated clock error and the actual clock error value. In the fourth embodiment, the positioning calculation unit has a function of detecting a clock reset, and prevents a discontinuity from occurring in the positioning result when the clock is reset.

  FIG. 13 is a configuration diagram of the positioning calculation unit 800 in the fourth embodiment. The positioning calculation unit 800 according to the fourth embodiment is newly added to the configuration of the positioning calculation unit 700 according to the third embodiment, and includes a data reception time lag calculation unit 310, a clock reset detection unit 320, and a clock reset compensation unit 330. Is provided. In the fourth embodiment, the same or corresponding parts as those in the first to third embodiments are denoted by the same reference numerals and description thereof is omitted. One epoch is 1 (second).

FIG. 14 is a diagram of an operation flow of the positioning calculation unit 800 in the fourth embodiment. 15 to 17 are diagrams showing a continuation of the operation flow of the positioning calculation unit 800 according to the fourth embodiment. FIG. 18 is a diagram showing the data reception time t and the distance conversion clock error ΔS for explaining the operation flow of the positioning calculation unit 800.

Next, the operation of the positioning calculation unit 800 in the fourth embodiment will be described with reference to FIGS. 13 and 14 to 18.
(1) The operations of S401 to S404 are the same as the operations of S301 to S304 in the third embodiment.

(2) In S405, the data reception time deviation calculation unit 310 performs a process of rounding down or rounding up the fractions after the decimal point of the data reception time tgps output in units of seconds in the number of seconds passed from the beginning of the week. The data reception time tgps output from the signal receiving unit 200 does not become an integer due to a clock error included in the positioning device, but a fraction occurs below the decimal point of tgps. Then, a value after rounding down or rounding up the fraction of the data reception time tgps is set to tgps_true.

For example, when the data reception time tgps is 3.004 (seconds), the data reception time shift amount calculation unit 310 performs processing of truncating the decimal part of tgps, and the value tgps_true after the truncation is 3.000 (seconds). It becomes. When the data reception time tgps is 2.995 (seconds), processing for rounding up the decimal point of tgps is performed, and the value tgps_true after rounding up is 3.000 (seconds).
In this way, the data reception time deviation amount calculation unit 310 performs processing for converting the data reception time tgps into an integer. The determination of rounding down or rounding up depends on, for example, rounding down if the decimal place is less than 0.5, and rounding up if 0.5 or more.

(3) In S406, the positioning time deviation calculation unit 310 calculates the difference Δtgps between the data reception time tgps and tgps_true (Δtgps = tgps−tgps_true).

(4) In S407, it is determined whether or not the positioning calculation is based on positioning information after the third epoch (I ≧ 3) after starting positioning. If it is after the third epoch, the process proceeds to S408. If it is not after the third epoch, the operation proceeds to S430 to S440 (FIG. 17).

(5) In S430 to S438, the same operations as S320 to S328 in the third embodiment are performed. That is, based on the received positioning information 295, the satellite position is calculated and the pseudorange is corrected, and then the positioning calculation is performed by equations (1a) to (4a) to calculate the positioning result. At the same time, the distance conversion clock error ΔS obtained is stored in the clock error ΔS-1 before one epoch or the clock error ΔS-2 before two epochs according to the determination in S430.

(6) Next, in S439, the difference Δtgps obtained in S405 is stored as a value Δtgps-1 one epoch before. Next, in S440, the pseudo-range PR of the current epoch corrected in S432 is stored in the pseudo-distance PR_OLD in the previous epoch.

(7) If the determination result is the third and subsequent epochs in S407, the difference ΔSd between the distance converted clock error ΔS-1 before one epoch and the distance converted clock error ΔS-2 before two epochs is calculated in S408. (ΔSd = ΔS−1−ΔS−2).

(8) In S409, the positioning time lag calculation unit 310 calculates the time difference Δtgps_reset for clock reset detection using the equation (8). Here, Δtgps-1 is a difference value between the data reception time tgps-1 one epoch before and tgps_true-1 obtained by rounding up or rounding down the fraction of tgps-1 (Δtgps-1 = tgps-1−tgps_true) -1).

      Δtgps_reset = | Δtgps Δtgps-1 | Formula (8)

(9) In S410, the positioning time lag calculation unit 310 stores the calculated Δtgps as a value Δtgps-1 one epoch before.

(10) In S411, the clock reset detection unit 320 compares Δtgps_reset with a preset threshold Clock_reset. From this comparison, it is determined whether or not a clock reset has occurred.
The threshold Clock_reset for clock reset detection is set to 9 (milliseconds), for example, but may be set according to the specification of the signal receiving unit 200.

(11) When a clock reset is detected in S411, the clock reset compensator 330 compensates for the distance conversion clock error ΔS in S412 to S414.

(12) In S412, the difference ΔPR between the pseudo-range PR_OLD of the previous epoch and the pseudo-range PR of the current epoch is calculated (ΔPR = PR−PR_OLD).

(13) In S413, the clock reset compensator 330 determines whether the clock error ΔS-1 before one epoch is positive or negative.

(14) In S414 and S415, the clock reset compensator 330 adds or subtracts the pseudo-range difference ΔPR to the clock error ΔS-1 before one epoch according to the sign of ΔS-1 in S413. Thus, an estimated value ΔS ′ of the distance conversion clock error in the current epoch is calculated (ΔS ′ = ΔS−1−ΔPR or ΔS ′ = ΔS−1 + ΔPR).

(15) If no clock reset is detected in S411, time extrapolation of the clock error is performed in S416, and an estimated value ΔS ′ of the distance conversion clock error in the current epoch is calculated (ΔS ′ = ΔS−1). + ΔSd).

(16) In S417 to S422, the same operations as S308 to S313 in the third embodiment are performed.
That is, the time correction unit 340 corrects the data reception time tgps based on the estimated distance conversion clock error ΔS ′ (S417).
Then, using the pseudo distance corrected by the pseudo distance correction unit 380 and the GPS satellite position calculated based on the data reception time tcal after correction by the satellite position calculation unit 370, the positioning calculation is performed according to equations (1b) to (4b). (S420).
Next, the clock drift calculation unit 360 stores the distance converted clock error ΔS-1 before one epoch as the distance converted clock error ΔS-2 two epochs before (S421).
The clock drift calculation unit 360 stores the distance conversion clock error ΔS obtained simultaneously with the positioning calculation in the clock error ΔS−1 one epoch before (S422).
Returning to S302, positioning is continued.

  FIGS. 19 to 21 show examples of positioning results of the positioning device 800 according to the fourth embodiment. FIG. 19 is a diagram showing the clock error δ obtained by the positioning calculation with respect to the elapsed time. FIG. 20 is an example of a positioning result in the fourth embodiment. The vertical axis represents the amount of error (Δlatitude, Δlongitude) in the latitude and longitude directions of the position obtained by the positioning calculation. FIG. 21 is a plot of positioning results for each elapsed time, where the vertical axis is Δlatitude and the horizontal axis is Δlongitude.

  Compared with the example of the conventional positioning results of FIGS. 29 to 32, it can be seen that there is no correlation with the change of the clock error and the accuracy is improved. It can also be seen that there is no discontinuity in the positioning results even when the clock is reset.

  Thus, in the fourth embodiment, the difference Δtgps between the data reception time tgps in the current epoch and the tgps_true obtained by rounding up or rounding down the fraction of tgps, and the data reception times tgps-1 and tgps-1 in the previous epoch The absolute value of the difference from the difference Δtgps-1 from tgps_true-1 rounded up or rounded down was obtained, and the time difference Δtgps_reset for clock reset detection was shown.

  Then, it was shown that the clock reset is detected by comparing the magnitude of this Δtgps_reset with a preset threshold value Clock_reset.

  If a clock reset is detected, the difference ΔPR (ΔPR = PR−PR_old) between the pseudorange PR at the current epoch and the pseudorange PR_old at the previous epoch is obtained as a clock error ΔS−1 at the previous epoch. It was shown that the distance conversion clock error ΔS is corrected by clock reset by adding or subtracting to.

As described above, in the fourth embodiment, the positioning calculation unit 800 includes the data reception time lag calculation unit 310, the clock reset detection unit 320, and the clock reset compensation unit 330, and detects clock reset and clock error when clock reset occurs. The correction was implemented. As a result, even in a positioning device using an inexpensive clock such as XO as an internal clock, it is possible to prevent discontinuity of positioning results caused by clock reset and obtain highly accurate positioning results in real time. effective.
Further, by providing a positioning calculation unit 800 that performs positioning calculation by processing the positioning information 295 output from the signal receiving unit 200 outside the signal receiving unit 200, the calculation processing method can be easily changed and improved, and There is an effect that a positioning result with high accuracy can be easily obtained.

  In the fourth embodiment, since the data reception time tgps output from the signal receiving unit 200 is used for detecting the clock reset, there is an effect that the clock reset can be easily detected.

  To supplementarily explain this effect, in the fourth embodiment, the clock reset is detected based on the data reception time t. However, the clock reset is detected based on the fluctuation of the pseudo distance PR output from the signal receiving unit 200. Also good. However, in the detection using the pseudorange PR, if a shield or the like enters between the satellite observing the pseudorange and the positioning device, the positioning signal from the satellite cannot be received, and the pseudorange information cannot be acquired. In some cases, clock reset detection may fail. For this reason, in order to reliably detect a clock reset based on a pseudorange, it is necessary to input a pseudorange of a plurality of GPS satellites and to detect a clock reset by monitoring the pseudoranges of the plurality of GPS satellites. The amount of calculation increases. On the other hand, in the detection based on the data reception time t, since the data reception time t is a common value for all GPS satellites, even if positioning signals from some GPS satellites cannot be received suddenly by an obstruction, The reception time t can be acquired. For this reason, it is only necessary to pay attention to only one variable of the data reception time t in detecting the clock reset, and there is an effect that the detection of the clock reset can be simplified.

  The positioning calculation unit 800 may be in the signal receiving unit 200, and the signal receiving unit 200 may output the positioning calculation result 395. Further, the signal receiving unit 200 may be in the positioning calculation unit 300, and the positioning calculation unit 300 may receive the positioning signal 10 from the positioning signal.

Embodiment 5 FIG.
In the third and fourth embodiments, for the third and subsequent epochs after the start of positioning, the clock error data of the current epoch is estimated by using the clock error data obtained by the first and second epoch positioning calculations. It was possible to perform positioning calculation at the current epoch using the estimated clock error. For this reason, in the positioning calculation immediately after the start of positioning, such as the first epoch or the second epoch, or immediately after unpositioned, such as after passing through the tunnel, the clock error can be estimated because there is no previous clock error data. However, accuracy degradation occurs in the positioning result immediately after the start of positioning. In the fifth embodiment, the positioning accuracy immediately after the start of positioning is improved.

FIG. 22 is a configuration diagram of the positioning calculation unit 900 according to the fifth embodiment. FIG. 23 is a diagram for explaining an operation flow of the positioning calculation unit 900.
The positioning calculation unit 900 includes an epoch determination unit 601, a first positioning calculation unit 605, a second positioning calculation unit 606, and a control unit 301 that controls the overall operation of the positioning calculation unit 900.

The configuration of the first positioning calculation unit 605 is the same as the configuration of the positioning calculation unit 300 in the first embodiment shown in FIG. 3, and the operation of the first positioning calculation unit 605 is the first embodiment shown in FIG. This is the same as the operation flow of the positioning calculation unit 300 in FIG.

 The configuration of the second positioning calculation unit 606 is the same as the configuration of the positioning calculation unit 800 in the fourth embodiment shown in FIG. 13, and the operation of the second positioning calculation unit 606 is shown in FIGS. It is the same as the operation flow of the positioning calculation unit 800 in the fourth embodiment.

Next, the operation of the positioning calculation unit 900 in the fifth embodiment will be described with reference to FIGS.
(1) The control unit 301 resets the epoch counter I to 0 when the power of the positioning device is turned on (S600).

(2) Upon receiving the positioning information 295, the control unit 301 adds 1 to the epoch counter, and the epoch determination unit 601 determines whether the epoch counter I is less than 3 (I <3) (S610).

 (3) If the epoch counter I is less than 3, the control unit 301 determines that there is no past clock error data, and the first positioning calculation unit 605 receives the positioning information 295 and performs the positioning calculation (S620). . The first positioning calculation unit 605 calculates the satellite position after correcting the time using the distance-converted clock error ΔS obtained by the first positioning calculation as described in the first embodiment, and calculates the second positioning calculation. The positioning calculation result 395 obtained by the above is output.

 (4) If the epoch counter I is not less than 3, the control unit 301 determines that there is past clock error data, and the second positioning calculation unit 606 receives the positioning information 295 and performs positioning calculation (S630). . The second arithmetic unit 606 calculates the estimated value ΔS ′ of the distance-converted clock error at the current clock from the past distance-converted clock error value as described in the fourth embodiment, and performs positioning using the estimated value ΔS ′. The calculation is performed, and the obtained result is output as a positioning calculation result 395.

As described above, the fifth embodiment includes the first positioning calculation unit 605 and the second positioning calculation unit 606. When there is no previous clock error value, the clock error corrected by the first positioning calculation unit is used. The second positioning calculation unit outputs the obtained result as a positioning calculation result 395, and when there is a previous clock error value, the second positioning calculation unit calculates the clock error at the current epoch from the previous clock error. Since the positioning calculation is performed by estimation and the obtained result is output as the positioning calculation result 395, a highly accurate positioning result can be obtained even immediately after the positioning is started.
Further, by providing a positioning calculation unit 900 that processes the positioning information 295 output from the signal receiving unit 200 and performs the positioning calculation outside the signal receiving unit 200, the calculation processing method can be easily changed and improved, and The effect that a positioning result with high accuracy can be easily obtained can be obtained.

  Although the fifth embodiment has been described with reference to an example immediately after the start of positioning such as the first epoch or the second epoch, this embodiment is also used for positioning calculation immediately after an unpositioned state such as after passing through a tunnel. The invention in 5 can obtain the same effect.

  Note that the positioning calculation unit 900 may be in the signal receiving unit 200, and the signal receiving unit 200 may output the positioning calculation result 395. Further, the signal receiving unit 200 may be in the positioning calculation unit 300, and the positioning calculation unit 300 may receive the positioning signal 10 from the positioning signal.

Embodiment 6 FIG.
In the third to fifth embodiments, the clock error of the current epoch is estimated using the clock error data of the previous epoch. In the sixth embodiment, the temperature sensor 500 and the clock drift storage unit 352 are provided in the positioning device 100, and the value of the clock drift ΔSdrift with respect to the temperature stored in the clock drift storage unit 352 is used, thereby converting the distance in the current epoch. Estimate the clock error ΔS ′.

Here, the clock drift ΔSdrift refers to the time change rate of the distance conversion clock error ΔS.

FIG. 24 is a configuration diagram of the positioning device 100 according to the sixth embodiment. FIG. 25 is a configuration diagram of the positioning calculation unit 1000 according to the sixth embodiment.
The positioning device 100 according to the sixth embodiment includes a temperature sensor 500, and the positioning calculation unit 300 includes a clock drift storage unit 352. In the sixth embodiment, the same or corresponding parts as those in the first to fifth embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 26 shows an example of a correspondence table between the clock temperature T stored in the clock drift storage unit 352 and the clock drift ΔSdrift. When an inexpensive XO without a temperature compensation circuit is used for the internal clock of the positioning apparatus 100, since there is no temperature compensation, XO shows a different clock error for each temperature, and a distance conversion clock error ΔS is as shown in FIG. Temperature dependence. Thus, since the clock error ΔS varies with temperature, the clock drift ΔSdrift also shows temperature dependence.

In the example shown in FIG. 26, the clock drift ΔSdrift is about +7 (μs / s) at a low temperature of −10 ° C., but decreases to about −7 (μs / s) at a high temperature of 60 ° C. Thus, by measuring the clock drift ΔSdrift that fluctuates with respect to the temperature in advance and storing the measurement result in the clock drift storage unit 352, the clock drift can be estimated by inputting the apparatus temperature information. .

  The operation of the positioning calculation unit 300 according to the sixth embodiment will be described with reference to FIGS. In the sixth embodiment, the same or corresponding parts as those in the first to fifth embodiments are denoted by the same reference numerals and description thereof is omitted.

(1) The temperature sensor 500 installed in the vicinity of the signal receiving unit 200 outputs temperature information 505 that is the temperature of the installation location to the clock error time extrapolating unit 350.

(2) The clock error time extrapolation unit 350 that has received the temperature information 505 accesses the clock drift storage unit 352 and acquires information on the clock drift ΔSdrift corresponding to the received temperature.

(3) The clock error time extrapolation unit 350 outputs the acquired clock drift ΔSdrift to the time correction unit 340.

(4) The time correction unit 340 calculates the clock error ΔS ′ at the current epoch by adding the clock drift ΔSdrift acquired at the current epoch to the clock error ΔS−1 one epoch before (ΔS ′ = ΔS -1 + ΔSdrift).

 (5) Thereafter, for example, the positioning calculation is performed according to the operation flow of the positioning calculation unit 300 in the fourth embodiment (steps shown in S408 and subsequent steps in FIG. 15).

As described above, in Embodiment 6, the positioning calculation unit 1000 includes the temperature sensor 500 and the clock drift storage unit 352. By providing a database of the clock drift amount at each temperature in the positioning calculation unit 1000 in advance, the clock error at the current epoch can be estimated easily. And while reducing the calculation load of the positioning calculation part 1000, a highly accurate positioning result can be obtained in real time.
Further, by providing a positioning calculation unit 1000 that processes the positioning information 295 output from the signal receiving unit 200 and performs a positioning calculation outside the signal receiving unit 200, the calculation processing method can be easily changed and improved, and It is easy to obtain a highly accurate positioning result.

Here, another example of the sixth embodiment will be described.
The clock error time extrapolation unit 350 compares the clock drift acquired from the clock drift storage unit 352 (hereinafter referred to as ΔCd_a) with the clock drift acquired from the clock drift calculation unit 360 (hereinafter referred to as ΔCd_b). The calculated clock drift ΔSd may be output to the time correction unit 340.

  As an example, ΔCd_a and ΔCd_b are compared, and if the difference between ΔCd_a and ΔCd_b is within a preset value, ΔCd_b is output to clock correction unit 340 as clock drift ΔCd, and ΔCd_a is clocked if not within the value. The drift ΔCd may be output to the time correction unit 340.

  As a result, even if the clock error ΔSd_b calculated by the clock drift calculation unit 360 suddenly includes a large error, the accuracy of the positioning calculation result 395 is prevented by using ΔCd_a for the positioning calculation. be able to.

  As another example of the sixth embodiment, the clock error time extrapolation unit 350 inputs the distance converted clock errors ΔCd_a and ΔCd_b, and calculates the clock drift ΔSd estimated from the values of ΔCd_a and ΔCd_b. You may make it output to 340.

  As another example of the sixth embodiment, the clock error time extrapolation unit 350 inputs ΔCd_a and ΔCd_b, and outputs the clock drift ΔSd estimated from the values of ΔCd_a and ΔCd_b to the time correction unit 340. At the same time, the estimated clock drift ΔSd and the temperature information 505 at that time may be returned to the clock drift storage unit 352, and the clock drift amount data stored in the clock drift storage unit 352 may be sequentially updated.

  Note that the positioning calculation unit 1000 may be in the signal receiving unit 200, and the signal receiving unit 200 may output the positioning calculation result 395. Further, the signal receiving unit 200 may be in the positioning calculation unit 300, and the positioning calculation unit 300 may receive the positioning signal 10 from the positioning signal.

Embodiment 7 FIG.
In the first to sixth embodiments, the pseudo distance correction information receiving unit 382 may acquire correction information from the outside, and the pseudo distance correcting unit 380 may correct the pseudo distance.

FIG. 28 shows an example of a positioning system to which the positioning device 100 is applied. Here, the positioning device 100 may receive, for example, correction information 11 in a DGPS (Differential-GPS) positioning method from a DGPS reference station (or base station) 50. In addition to this, the positioning apparatus 100 may receive correction information 11 (surface correction parameter) in the positioning method of FKP-DGPS (Flauchen color Parameter-DGPS) from the reference station (or reference station) 50. Good.

As described above, in the seventh embodiment, the positioning device 100 can further improve the positioning accuracy by acquiring the correction information from the outside.

It is a block diagram of the positioning apparatus of Embodiment 1 in this invention. It is a block diagram of the positioning signal receiving part of Embodiment 1 in this invention. It is a block diagram of the positioning calculating part of Embodiment 1 in this invention. It is the figure which showed the operation | movement flow of the positioning calculating part of Embodiment 1 in this invention. It is the figure which showed the calculation process of the satellite position calculation part of Embodiment 1 in this invention. It is the figure which showed the operation | movement flow of the positioning calculation part of Embodiment 2 in this invention. It is a figure which shows the clock error threshold value of Embodiment 2 in this invention. It is a block diagram of the positioning calculation part of Embodiment 3 in this invention. It is the figure which showed the operation | movement flow of the positioning calculating part of Embodiment 3 in this invention. It is the figure which showed the continuation of the operation | movement flow of the positioning calculation part of Embodiment 3 in this invention. It is a figure showing the clock error for demonstrating the operation | movement flow of the positioning calculation part of Embodiment 3 in this invention. It is a figure explaining the flow of the data of the clock error of Embodiment 3 in this invention. It is a block diagram of the positioning calculating part of Embodiment 4 in this invention. It is the figure which showed the operation | movement flow of the positioning calculating part of Embodiment 4 in this invention. It is the figure which showed the continuation of the operation | movement flow of the positioning calculating part of Embodiment 4 in this invention. It is the figure which showed the continuation of the operation | movement flow of the positioning calculating part of Embodiment 4 in this invention. It is the figure which showed the continuation of the operation | movement flow of the positioning calculating part of Embodiment 4 in this invention. It is a figure showing the clock error for demonstrating the operation | movement flow of the positioning calculation part of Embodiment 4 in this invention. It is a figure which shows an example of the positioning result of Embodiment 4 in this invention. It is a figure which shows an example of the positioning result of Embodiment 4 in this invention. It is a figure which shows an example of the positioning result of Embodiment 4 in this invention. It is a block diagram of the positioning apparatus of Embodiment 5 in this invention. It is a block diagram of the positioning calculating part of Embodiment 5 in this invention. It is a block diagram of the positioning apparatus of Embodiment 6 in this invention. It is a block diagram of the positioning calculating part of Embodiment 6 in this invention. It is a figure which shows an example of the clock drift value of Embodiment 6 in this invention. It is a figure which shows an example of the temperature dependence of clock error (DELTA) S in the conventional positioning apparatus. It is a figure which shows an example of the positioning system in Embodiment 7 in this invention. It is an example of the positioning result of the conventional positioning apparatus. It is an example of the positioning result of the conventional positioning apparatus. It is an example of the positioning result of the conventional positioning apparatus. It is an example of the positioning result of the conventional positioning apparatus.

Explanation of symbols

  1 GPS satellite, 10 positioning signal, 100 positioning device, 200 positioning signal receiving unit, 205 positioning signal receiving antenna, 220 RF front end processing unit, 221 XO, 230 A / D conversion unit, 260 baseband chip processing unit, 300 positioning calculation Unit, 301 control unit, 310 positioning time deviation calculation unit, 320 clock reset detection unit, 330 clock reset compensation unit, 340 time correction unit, 350 clock error time extrapolation unit, 355 estimated clock error ΔC ′, 360 clock drift calculation Unit, 365 clock error, 370 satellite position calculation unit, 380 pseudo distance correction unit, 382 reception of pseudo distance correction value, 390 positioning calculation unit, 392 determination unit, 393 distance conversion clock error, 396 reception time after correction, 601 epoch determination unit , 605 First positioning calculation unit, 606 2 positioning calculation unit, 700 positioning calculation unit in the third embodiment, 800 positioning calculation unit in the fourth embodiment, 900 positioning calculation unit in the fifth embodiment, 1000 positioning calculation unit in the sixth embodiment.

Claims (6)

A positioning device comprising a signal receiving unit that receives a positioning signal from a positioning satellite, calculates a pseudo distance based on the positioning signal, and a positioning calculation unit that performs a positioning calculation using the pseudo distance,
The signal receiving unit has an XO (Xtal Oscillator) as an internal clock, and when the clock error of the XO exceeds a certain value with respect to a reference clock used by a positioning satellite, a clock reset is executed to prevent the clock error from increasing. With a clock reset function
When the positioning calculation unit detects that the clock reset has been executed, the difference between the pseudo distances before and after the detection of the clock reset is offset-corrected to a distance conversion clock error before the clock reset detection, and the clock reset detection is performed. after the distance the converted clock error, positioning device, characterized in that the positioning calculation using the distance conversion clock error after the offset correction. The positioning calculation unit determines that the clock reset is executed when a difference in data reception time of the positioning signal repeatedly output by the signal reception unit is equal to or greater than a predetermined threshold value. The described positioning device. A pseudo-range and navigation message of each positioning satellite acquired by a signal receiver having an internal clock substantially synchronized with a reference clock mounted on the positioning satellite from each of the positioning satellites, and the signal reception A positioning calculator that calculates the position of the signal receiver using positioning information including a data reception time output by an internal clock provided in the signal receiver that is a time at which the instrument receives the positioning signal,
The satellite position related to the positioning satellite obtained from the positioning information, the pseudo distance, the position of the signal receiver, and the distance conversion clock error representing the error amount of the pseudo distance caused by the clock error of the internal clock as variables. A time correction unit that calculates a clock error of the internal clock and corrects the data reception time by simultaneous equations
A satellite position calculator that recalculates the satellite position using the corrected data reception time corrected by the time correction unit;
Positioning calculation for calculating the position of the signal receiver by simultaneous equations using the satellite position recalculated by the satellite position calculation unit, the pseudorange, the position of the signal receiver, and the distance conversion clock error as variables. And
A clock reset detector that detects a clock reset that is executed to synchronize the internal clock and the reference clock when the clock error is equal to or greater than a predetermined value;
When the clock reset detection unit detects the clock reset, a clock error is calculated from a difference in pseudo distance before and after the detection of the clock reset, and the clock reset compensation unit outputs the clock error to the time correction unit;
A positioning arithmetic unit comprising: An internal clock that is substantially synchronized with a reference clock mounted on the positioning satellite, receives a positioning signal from the positioning satellite, receives a pseudo distance indicating a distance to the positioning satellite, a navigation message, and the positioning signal. A signal receiving unit that outputs positioning information including a data reception time output by the internal clock at a time;
A positioning calculation unit that calculates the position of the signal receiving unit using the positioning information;
A positioning device comprising:
The positioning calculation unit
The satellite position related to the positioning satellite obtained from the positioning information, the pseudo distance, the position of the signal receiving unit, and the distance conversion clock error representing the error amount of the pseudo distance caused by the clock error of the internal clock as variables. A time correction unit that calculates a clock error of the internal clock and corrects the data reception time by simultaneous equations
A satellite position calculator that recalculates the satellite position using the corrected data reception time corrected by the time correction unit;
Positioning calculation for calculating the position of the signal receiving unit by simultaneous equations using the satellite position recalculated by the satellite position calculating unit, the pseudo distance, the position of the signal receiving unit, and the distance conversion clock error as variables. And
A clock reset detector that detects a clock reset that is executed to synchronize the internal clock and the reference clock when the clock error is equal to or greater than a predetermined value;
When the clock reset detection unit detects the clock reset, a clock error is calculated from a difference in pseudo distance before and after the detection of the clock reset, and the clock reset compensation unit outputs the clock error to the time correction unit.
A positioning device characterized by that. 5. The positioning apparatus according to claim 4, wherein the internal clock is an XO (Xtal Oscillator). This is a positioning calculation method that performs positioning calculation using the pseudo distance output from a signal receiver that has an internal clock XO (Xtal Oscillator), receives a positioning signal from a positioning satellite, and calculates a pseudo distance based on the positioning signal. And
When the signal receiver detects that the clock error of the XO is equal to or greater than a certain value and performs a clock reset to prevent the clock error from increasing, the difference in the pseudo distance before and after the detection of the clock reset is calculated. A positioning calculation method characterized in that an offset correction is performed on a distance conversion clock error before clock reset execution to obtain a distance conversion clock error after the clock reset is detected, and a positioning calculation is performed using the distance conversion clock error after the offset correction.

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