JP2012032331A - Gps positioning operation method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of improving positioning accuracy at a measuring point as a result of improving calculation accuracy while simplifying a method for calculating a pseudo distance.SOLUTION: A GPS positioning operation device 10 performs positioning operation (S111) by: (S105) acquiring, from orbit information included in a signal sent from a GPS satellite, orbit information on a position A, an orbit speed v, time tb, an altitude h of the GPS satellite at the time when the GPS satellite sends the signal; (S105) calculating, from the orbit speed v, time tb and a time difference t=tr-tb, a position B of the GPS satellite at the time tr when a measuring point receives the signal; (S106) calculating, from a length ct of a first line segment connecting the position B of the GPS satellite and the position O of the measuring point, and the altitude h, a first angle α of the horizon with respect to the first line segment; and (S107) calculating the length of a second line segment cs connecting the position A of the GPS satellite and the position O of the measuring point, based on the length ct of the first line segment, the first angle α and the orbit speed v.

Description

  The present invention relates to a GPS positioning calculation method and a positioning calculation apparatus that receive signals emitted from a plurality of GPS (Global Positioning System) satellites and detect the positions of measurement points on the ground.

  In order for the GPS receiver to detect the position of the current location, it is necessary to know the distance to the GPS satellite and the position of the GPS satellite. In the signal sent from the GPS satellite, data called a navigation message (hereinafter referred to as navigation data) is modulated, and orbit information is included in the navigation data.

  A GPS receiver receives navigation data from a plurality of GPS satellites and measures the position of the GPS satellites and the distance from the GPS satellites to a measurement point, for example, an automobile, a ship, an aircraft, a work vehicle, a portable terminal For example, the position of the moving body as the measurement point is detected.

  By the way, in the GPS receiver, a time difference is generated between a transmission time point when a signal is transmitted from a GPS satellite and a reception time point when the signal is received. In this case, if the time completely matches between the clock provided to the GPS receiver and the atomic clock provided to the GPS satellite, the navigation data is received with a delay of the radio wave propagation time. . Therefore, the GPS receiver can calculate the distance to the GPS satellite by multiplying the propagation time of the radio wave by the speed of light (the propagation speed of the electromagnetic field).

  However, in many cases, the time is not exactly the same between both watches. For this reason, the GPS receiver obtains the distance from the GPS satellite as a “pseudo-range” including a time error. Here, the “pseudo distance” means a distance from the GPS satellite to the GPS receiver, and is measured by adding an error due to the advance of the clock of the GPS receiver to an accurate distance. That is, the GPS receiver obtains the pseudo distance by multiplying the propagation time obtained by subtracting the time when the GPS satellite transmits the signal from the time when the signal is received, by the speed of light. Then, the position of the GPS measurement point is calculated three-dimensionally from the position at the time of transmission of the GPS satellite and the calculated pseudo distance obtained by receiving the ephemeris of the navigation data (for example, Patent Document 1). (See FIG. 8).)

By the way, if the above-mentioned time error is small, the GPS receiver should be able to calculate the position of the measurement point with the three variables xyz based on the signal from the GPS satellite. However, since the time error Δt is very large, a technique for detecting the current location of the measurement point using four variables including one variable of the time error Δt is known.
For example, as shown in FIG. 6, the GPS receiver 105 needs to receive navigation data from at least four GPS satellites 101 to 104.

  In addition, there is a method using navigation data from four or more GPS satellites (see, for example, FIG. 1 of Patent Document 2). According to these techniques, a large error occurs in the calculated pseudo distance. As a result, there was a limit to the improvement of positioning accuracy. Therefore, as shown in FIG. 7, there are various methods for improving accuracy, such as a method of estimating an error in pseudorange from differential data that is a positioning result in a reference ground base station (fixed station receiver 106). Proposed. These methods have disadvantages such as increasing the complexity of the system and increasing the calculation time and cost.

  Possible causes of errors include clock errors and orbit errors in GPS satellites, ionospheric refraction and tropospheric refraction in signal propagation, and changes in antenna phase center, clock errors, and multipaths in GPS receivers. In addition, the clock error includes a time error due to the error of the clock itself, a special relativity called a relativistic effect, and a general relativity. Furthermore, the influence of random noise can be considered.

Many attempts have been made to suppress the influence of these errors. However, at present, there are no decisive measures, and there is still trial and error. Therefore, as described above, a method has been used in which data is acquired from four or more GPS satellites, or a pseudo-range is estimated from a positioning result at a reference ground base station.
Further, for example, as shown in FIG. 8, the relationship between the elevation angle and the positioning error is shown by a graph, and the dependence characteristic on the elevation angle (or zenith angle) is clarified as a factor of the error. For this reason, it is common to preferentially use GPS satellite data with a relatively small elevation error and a large elevation angle, and these errors complicate the pseudorange calculation method and system.

International Publication No. 2005/017552 Pamphlet Japanese Patent No. 3524018

  It is an object of the present invention to provide a technique capable of improving the calculation accuracy while simplifying the pseudo distance calculation method and consequently improving the detection accuracy of the current location at the measurement point.

  The invention according to claim 1 is a GPS positioning calculation method in which a signal transmitted by at least three GPS satellites is received by a receiver, and an arithmetic unit measures the position of a measurement point on the horizon based on the signal, Orbit information including the position A of the GPS satellite, the time tb, the orbital velocity v, and the altitude h from the navigation data included in the signal received by the receiver. From the obtained orbital velocity v and time tb, the measurement point obtains the position B of the GPS satellite at time tr when the measurement point received the signal. The first angle α of the horizon with respect to the first line segment calculated from the time difference t = tr−tb and connecting the position B of the GPS satellite and the position O of the measurement point is determined as the first line segment. Calculated from distance ct and altitude h The GPS satellite position A and the measurement based on the second step, the distance ct of the first line segment, the first angle α calculated in the second step, and the orbital velocity v. A third step of calculating the distance cs of the second line segment connecting the point position O, the position A of the at least three GPS satellites calculated in the third step, and the position O of the measurement point And a fourth step of calculating the position O of the measurement point from each distance cs between the first and second points.

  In the invention according to claim 2, in the GPS positioning calculation method according to claim 1, the second step includes the calculated first angle α and the orbital velocity of the GPS satellite acquired in the first step. v is used to calculate a second angle β of the horizon with respect to a second line segment connecting the position A of the GPS satellite at the time of emitting the signal and the current location O of the measurement point. .

According to a third aspect of the present invention, in the GPS positioning calculation method according to the first or second aspect, in calculating the first angle α or the second angle β, the second step has the following angular relationship. Expression (1) is calculated.

In the invention according to claim 4, in the GPS positioning calculation method according to claim 1, the third step calculates the following relational expression (2) in calculating the distance cs of the second line segment. It is characterized by that.

In the invention according to claim 5, in the GPS positioning calculation method according to claim 1, the third step calculates the distance cs of the second line segment by the following relational expressions (3) and (4 ) To calculate the speed in the rotational motion.

In the invention according to claim 6, in the GPS positioning calculation method according to claim 1, in calculating the position O of the measurement point, the fourth step calculates the following relational expression (5). And

The invention according to claim 7 is a GPS positioning arithmetic unit in which a receiver receives signals emitted from at least three GPS satellites, and an arithmetic unit calculates a position O of a measurement point on the horizon. A navigation data acquisition unit for acquiring orbit information including a position A, a time tb, an orbital velocity v, and an altitude h of the GPS satellite at the time of emitting the signal from the navigation data included in the signal; From the acquired orbital velocity v and time tb, the position B of the GPS satellite at the time tr when the measurement point receives the signal is calculated from the time difference t = tr−tb. An elevation angle calculation unit that calculates a first angle α of the horizon with respect to a first line segment connecting the position O of the measurement point from a distance ct and an altitude h of the first line segment;
Based on the distance ct of the first line segment, the first angle α calculated by the elevation angle calculation unit, and the orbital velocity v, the position A of the GPS satellite and the position O of the measurement point are connected. And a second distance between each position A of the respective GPS satellites calculated by the pseudo distance calculation unit and the position O of the measurement point. And a positioning calculation unit that calculates a position O of the measurement point from a distance cs of minutes.

  According to the first aspect of the present invention, the computing unit at the time tr when the measurement point receives the signal from the orbital velocity v acquired from the signal received by the receiver and the time tb in the second step. The position B of the GPS satellite is calculated, the first angle α of the horizon with respect to the first line segment connecting the position B of the GPS satellite and the position O of the measurement point, the distance ct of the first line segment and the altitude Calculate from h. Then, based on the distance ct of the first line segment in the third step, the first angle α calculated in the second step, and the orbital velocity v, the position A of the GPS satellite and the position O of the measurement point The distance cs of the second line segment connecting the two is calculated as a pseudo distance.

  Therefore, in order to calculate the pseudorange, information on the orbital velocity v and the angle α is newly required. However, the distance ct between the GPS satellite and the measurement point at the time of signal reception, which is conventionally used as the pseudorange, The pseudo distance can be calculated by replacing the distance cs between the GPS satellite and the measurement point at the time of signal transmission. Therefore, the pseudo distance can be easily calculated with high accuracy.

  In the fourth step, the position at the measurement point O is calculated by calculating the position of the measurement point O based on the position information at the time of signal transmission of at least three GPS satellites and the calculated pseudoranges. Enables improved detection accuracy. For this reason, it is possible to reduce the number of GPS satellites necessary for the positioning calculation. Further, since the reference positioning data from the ground base station is not required, the pseudo distance calculation method is simplified.

  According to the second aspect of the invention, from the calculated angle α and the orbital velocity v of the GPS satellite acquired in the first step, the position A of the GPS satellite and the current location O of the measurement point when the signal is generated. The angle β of the horizon with respect to the line connecting the two is calculated. For this reason, in addition to the angle α, data on the angle β is required. However, the calculation of the pseudo distance can be easily performed with high accuracy simply by replacing the conventional pseudo distance ct with the original pseudo distance cs. Is possible.

  According to the invention of claim 3, by defining the relationship between the angle α and the angle β by the angle relational expression (1), the pseudo distance can be calculated without depending on the magnitude of the zenith angle (elevation angle). Therefore, the calculation accuracy of the pseudo distance is improved.

  According to the fourth aspect of the present invention, information on the orbital velocity v and the angle α is required to calculate the pseudo distance cs. However, the distance ct between the GPS satellite and the measurement point at the time of signal reception, which was conventionally used as the pseudo distance, is calculated by replacing the distance cs between the GPS satellite and the measurement point at the time of signal transmission, which is the original pseudo distance. Therefore, the pseudo distance can be calculated with high accuracy.

  According to the invention of claim 5, even when the GPS satellite takes an ellipse or other complicated orbits, it is possible to calculate the pseudo distance cs with high accuracy without causing an error.

  According to the invention of claim 6, measurement is performed by calculating the position of the measurement point O based on each position information B and the calculated pseudoranges cs at the time of signal transmission of at least three GPS satellites. The position detection accuracy at the point O can be improved. In addition, since a large number of GPS satellites are not used and reference positioning data from a base station on the ground is not required, the pseudo distance calculation method is simplified.

  According to the seventh aspect of the present invention, the elevation angle calculation unit calculates the time difference between the GPS satellite position B at the time tr when the measurement point receives the signal from the orbital velocity v acquired by the navigation data acquisition unit and the time tb. The first angle α of the horizon with respect to the first line segment connecting the position B of the GPS satellite and the position O of the measurement point is calculated from t = tr−tb, the distance ct of the first line segment and the altitude h Calculate from Then, based on the distance ct of the first line segment, the first angle α calculated by the elevation angle calculator, and the orbital velocity v, the pseudorange calculator calculates the position A of the GPS satellite and the position O of the measurement point. The distance cs of the second line segment connecting the two is calculated.

  For this reason, the number of GPS satellites necessary for the positioning calculation can be reduced, and the pseudo distance can be calculated without using the reference positioning data from the base station on the ground, so that the calculation method is simplified. In addition, when calculating the pseudo distance cs, the information of the angle α and the angle β is required. However, simply replacing the conventional pseudo distance ct with cs enables simple and highly accurate calculation of the pseudo distance. become.

  Then, the positioning calculation unit performs the positioning calculation of the measurement point based on the position information A of the GPS satellite at the time of signal transmission and the calculated pseudo distance cs, thereby improving the detection accuracy of the position at the measurement point. It is possible to provide a GPS positioning calculation device that can be used.

It is a figure which shows the structure of the GPS positioning calculating apparatus which concerns on the Example of this invention. It is the figure which expressed the basic idea of the GPS positioning calculation method based on the Example of this invention with two inertial systems. FIG. 3 is a diagram illustrating a relationship between angles α and β between GPS satellites having a measurement point as a base in the inertial system of FIG. 2. It is a flowchart which shows operation | movement of the GPS positioning calculating apparatus based on the Example of this invention. It is the figure which expressed the basic way of thinking of the GPS positioning calculation method which concerns on the Example of this invention with the rotation inertia system. It is the figure quoted in order to demonstrate the conventional GPS positioning calculation method. It is the figure quoted in order to demonstrate the GPS positioning calculation method using the differential data by the conventional fixed station receiver. It is the figure which showed the relationship between an elevation angle and the ranging error by GPS positioning with the graph.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a GPS positioning calculation apparatus 10 according to an embodiment of the present invention includes a receiver 11, an analog / digital converter 12 (A / D (analog / digital) converter 12), and a correlator 13. And an arithmetic unit 14, a control unit 15, and a storage unit 16. The receiver 11 includes an antenna 11a and a high frequency circuit 11b (hereinafter referred to as an RF (Radio Frequency Circuit) circuit 11b).

  The RF circuit 11b receives signals (radio waves) emitted from at least three GPS satellites 21 to 23 via the antenna 11a, down-converts the signals into intermediate frequency (IF) signals, and performs A / D conversion. To the device 12.

  The A / D converter 12 converts the analog signal output from the RF circuit 11 b into a digital signal and outputs the digital signal to the correlator 13 and the control unit 15.

  The correlator 13 detects the reception frequency based on the input digital signal. Specifically, the correlator 13 demodulates the digital signal output from the A / D converter 12 from the C / A (Coarse and Access) code of the GPS satellite to calculate the radio wave propagation delay.

  The control unit 15 acquires navigation data from the digital signal output from the A / D converter 12 and outputs the navigation data to the computing unit 14, and issues a positioning command including calculation of a pseudo distance to the computing unit 14. The arithmetic unit 14 has a function of performing pseudo distance calculation and positioning calculation.

  By the way, the navigation data used for GPS positioning includes “almanac data” and “ephemeris data”.

  “Almanac data” describes parameters that indicate the approximate positions of all GPS satellites, and can be used for about two weeks. This time limit is a limit due to the GPS satellite orbit shifting with time, and corresponds to the valid period of data. “Ephemeris data” is data describing detailed parameters of each satellite orbit information, and is used when the control unit 15 calculates the position of each GPS satellite. The time limit for the ephemeris data is about 2 hours.

  The computing unit 14 performs the following first to fourth steps under program control by the control unit 15.

Specifically, in the first step, from the navigation data included in the signal received by the RF circuit 11b, the positions A1, A2, and A3 of the GPS satellites 21 to 23 at the time of transmitting the signal (that is, the position A). Orbit information including each time tb, orbital velocity v, and altitude h is acquired.
In the subsequent second step, each position of the GPS satellites 21 to 23 at the time tr when the measurement point (GPS positioning calculation device 10) receives the signal from the orbital velocity v and the time tb acquired in the first step, respectively. B1, B2, and B3 (that is, position B) are calculated from the time difference t = tr−tb, and the first horizon of the horizon with respect to the first line segment connecting the position B of the GPS satellite and the position O of the measurement point is calculated. The angle α is calculated from the distance ct and the height h of the first line segment.

  Next, in the third step, the distance ct of the first line segment connecting the position B of each GPS satellite 21 to 23 calculated in the second step and the position O of the measurement point is calculated in the second step. Based on the first angle α and the orbital velocity v acquired in the first step, the distances cs1, cs2, cs3 (that is, distances cs1, cs2, cs3) connecting the position A of the GPS satellite and the position O of the measurement point. , Cs).

  In the fourth step, the distance cs (cs1 to cs1) between the position A (A1 to A3) of at least three GPS satellites 21 to 23 calculated in the third step and the position O of the measurement point is calculated. The position O of the measurement point is calculated from cs3).

  The first to fourth steps described above are programmed in advance and stored in the storage unit 16. The control unit 15 is configured by, for example, a microprocessor, and sequentially reads and executes a program stored in the storage unit 16, thereby causing the computing unit 14 to calculate the angle α and the pseudo distance cs. Finally, the positioning calculation of the position O of the measurement point is performed.

  In addition, the storage unit 16 also stores information such as the center position and radius r of the earth, the frequencies of the GPS satellites 21 to 23 that are GPS signal reception targets, and the speed of light c, which are referred to by the control unit 15. Yes.

  The calculation of the angle α and the positioning calculation of the pseudo distance cs and the measurement point position O are all described as being performed by the computing unit 14 under the control of the control unit 15. Instead, the control unit 15 may execute it.

  Hereinafter, the operation of the GPS positioning calculation apparatus 10 according to the embodiment of the present invention will be described. Before that, the basic concept of the GPS positioning calculation for explaining the embodiment will be described with reference to FIGS. And explain briefly.

  Here, as shown in FIG. 2 (a), a signal emitted from a GPS satellite at position A at time 0 (Time = 0) is received by the GPS positioning calculation device 10 at the measurement point O (P). Assume that At the time when the GPS positioning calculation device 10 of the measurement point receives the signal, the GPS satellite has already moved to the position B, not to the position A. In the following description, for convenience, the position A is referred to as a GPS satellite reference position, and the position B is referred to as a GPS satellite current position. In FIG. 2 (a), the GPS satellite is indicated by the symbol S.

  This state will be described with reference to the K coordinate indicated by a square (parallelogram) dotted line in FIG. 2B, that is, the coordinates of a GPS satellite, and the Q coordinate indicated by a square dotted line in FIG. To do.

  According to FIG. 2B, there are an O point and a B point on the diagonal of the K coordinate. Further, according to FIG. 2C, there is a point A on the right side of the upper side of the Q coordinate. The K coordinate moves in the right direction at a velocity v with respect to the Q coordinate. Here, the GPS satellite S is always at the B point of the K coordinate. FIG. 2D shows a state in which these two inertia systems (a coordinate system in which the law of inertia is established) are overlapped at Time = 0.

  In FIG. 2D, the reference position A and the current position B overlap. In this state, if the GPS satellite emits a signal at a radio wave propagation speed (light velocity c) from the point A to the point O of the K inertial system at the time of Time = 0, Time = t after the elapse of time t. The signal reaches point O. Thus, the distance between point B and point O is set to be ct. The distance between the O point and the P point is set to be vt.

  FIG. 2E shows a state when Time = t and point O and point P overlap after time t has elapsed. According to FIG.2 (e), the signal transmitted from the B point by the GPS satellite reaches the O point. The GPS positioning arithmetic unit 10 located in another Q inertial system appears as if the signal emitted from the point A has reached the point P. At this time, since the signal propagates at the speed of light even in the Q inertial system, the distance from the point A to the point P is cs.

  FIG. 3 shows an angle reflected in the relationship between the signal and the motion shown by the inertial system in FIG. Here, the elevation angle at the time of signal transmission of the GPS satellite (the angle of the line segment connecting the reference position A of the GPS satellite S and the position O of the measurement point with respect to the horizon e) is β, and the GPS positioning arithmetic unit 10 receives the signal. The elevation angle (the angle of the line segment connecting the current position B of the GPS satellite and the position O of the measurement point with respect to the horizon e) is α. Note that the altitude of the GPS satellite S is h, and the information on the altitude h and other information about the orbital speed v and the time t are all calculated from the navigation data transmitted from the GPS satellite S.

  From FIG. 3, the distance cs can be expressed by the following arithmetic expression (6) from the three-square theorem based on the right triangle ΔAOC.

  Here, ct · sin α is equal to the height h. Substituting the above equation (6) into ct · sin α = cs · sin β, which is the relationship between the lengths of two right triangles (ΔOAC, ΔOBD), leads to the following relationship (7). Is done. When this is further modified, the following angular relational expression (8) is derived. Subsequently, when the above length relational expression is considered with respect to this angular relational expression (8), the following time change expression (9) is derived.

  According to the angular relational expression (8), the measurement points are the angle α with respect to the horizon e of the line segment connecting the current position B of the GPS satellite S and the position O of the measurement point, the reference position A of the GPS satellite, and the measurement point. The angle β with respect to the horizon e of the line segment connecting the position O can be calculated. Then, from the angle α calculated by the angle relational expression (8), the pseudo distance cs between the measurement point and the GPS satellite S at the time of signal reception from the GPS satellite S is obtained by the following relational expression (10).

By the way, in the above angle relational expression (8), when β = π / 2, α = cos ⁻¹ (v / c), and the time variation expression (9) at this time is expressed by the following calculation expression (11). Deformed.

  The above arithmetic expression (11) coincides with the time delay due to the special relativity. That is, the special relativity indicates that the relationship between the angle α and the angle β cannot be considered. For this reason, conventionally, as shown in the graph of FIG. 8, the error tends to increase unless the pseudorange is calculated based on a signal from a satellite having a large elevation angle. This tendency is similar to the amount of zenith angle delay that has been reported as a conventional error. That is, as the zenith angle increases, the amount of delay increases at a rate of approximately 1 / cos, so the error increases.

  On the other hand, in the present embodiment, the relationship between the angle α and the angle β is reflected in the calculation of the pseudo distance, thereby making it possible to calculate the pseudo distance with high accuracy independent of the zenith angle. Further, it is not necessary to delay the GPS satellite clock with respect to the clock of the receiving station in consideration of special relativity. That is, the GPS satellite clock and the receiving station clock may be synchronized. The above is the idea that is the basis for the pseudorange calculation of two inertial systems that perform relative motion.

  Next, the operation of the GPS positioning calculation apparatus 10 according to the first embodiment of the present invention shown in FIG. 1 will be described in detail with reference to the processing flowchart of the control unit 15 shown in FIG.

  First, in step S101, the control unit 15 sets “0” to the value i of the counter assigned to the program. The counter counts the number of GPS satellites that are the targets of signal reception. Here, it is assumed that the position of the measurement point is detected using n (for example, three) GPS satellites 21 to 23. explain.

  Next, in step S102, the control unit 15 determines whether or not the RF circuit 11b has received a high-frequency analog signal transmitted from the first GPS satellite 21 that is the target of signal reception. In step S103, the IF signal Down-converted and output to the A / D converter 12.

  Next, the control unit 15 issues a signal conversion command to the A / D converter 12. In response to this, the A / D converter 12 converts the IF signal into a digital signal and outputs it to the correlator 13 and the control unit 15 in step S104, and the control unit 15 performs A / D conversion in step S105. Navigation data (orbital velocity v, time t, altitude h) is acquired from the obtained digital signal and output to the computing unit 14. At the same time, a pseudo distance calculation command is issued to the computing unit 14.

  Upon receiving the pseudo distance calculation command from the control unit 15, the computing unit 14 obtains the current position B of the GPS satellite at the time tr when the measurement point receives the signal from the orbital velocity v and the time tb acquired in step S 105. And time difference t = tr−tb. Then, the first angle α of the horizon with respect to the first line segment connecting the position B of the GPS satellite and the position O of the measurement point is calculated from the distance ct and the altitude h of the first line segment. That is, the first angle α is calculated from h = ct · sin α.

  Subsequently, from the first angle α calculated here and the acquired orbital velocity v of the GPS satellite, the reference position A of the GPS satellite and the position O of the measurement point when the signal is transmitted to the horizon e Is calculated based on the angular relational expression (8).

  Next, in step S107, the computing unit 14 determines the position A of the GPS satellite and the measurement based on the first angle α calculated in step S106, the distance ct of the first line segment, and the orbital velocity v. The distance cs of the second line segment connecting the point position O is calculated as a pseudo distance. The pseudo distance cs can be calculated by calculating the relational expression (10) described above. Subsequently, the calculator 14 delivers the calculation result to the control unit 15.

  When receiving the pseudo distance cs from the computing unit 14, the control unit 15 stores the pseudo distance cs in a predetermined area of the storage unit 16 in step S108, and increases the counter value i by “1” in step S109.

  Subsequently, in step S110, the control unit 15 compares the counter value i with the number “n” of GPS satellites to be received. Here, if the number of GPS satellites that have received the signal is less than “n”, the process returns to the GPS signal reception determination process in step S102, and thereafter, with respect to the GPS satellites 22-23, Similar processing (steps S102 to S109) is repeatedly executed.

  When the control unit 15 confirms that the counter value i has reached the number “n” of GPS satellites to be received in step S110, the control unit 15 issues a positioning calculation command to the calculator 14.

  Upon receiving a positioning calculation command from the control unit 15, the calculator 14 receives the three-dimensional positions S (x, y, z) of the GPS satellites 21 to 23 acquired previously and the calculated GPS values in step S <b> 111. Based on the pseudo distances cs1 to cs3 with the satellites 21 to 23, the positioning calculation of the measurement points is performed, and the result is delivered to the control unit 15.

  Note that the calculator 14 performs a positioning calculation of the three-dimensional position O (x, y, z) of the measurement point based on the positions S1 to S3 of the GPS satellites 21 to 23 and the calculated pseudo distances cs1 to cs3. The following relational expression (12) is calculated by calculation.

  By solving the above-described relational expression (12) (positioning relational expression based on simultaneous equations), the three-dimensional position O (x, y, z) of the measurement point can be calculated.

  Finally, in step S112, the control unit 15 passes the position and time of the measurement point to application software for car navigation such as route guidance, and a series of processes for the above-described measurement calculation of the measurement point. Exit.

  In the above-described GPS positioning calculation apparatus 10 according to the embodiment of the present invention, information on the orbital speed v and time tb acquired from the navigation data included in the signals emitted from three or more GPS satellites (here, 21 to 23) From the time difference t = tr−tb, the GPS satellite position B at the time tr when the measurement point receives the signal is calculated, and the first line segment connecting the GPS satellite position B and the measurement point position O is calculated. Is calculated from the distance ct and the altitude h of the first line segment, and based on the distance ct of the first line segment, the first angle α and the orbital velocity v, the GPS The distance cs of the second line segment connecting the position A of the satellite and the position O of the measurement point is calculated.

  For this reason, the calculation method is simplified because a large number of GPS satellites are not used and the reference positioning data from the ground base station is unnecessary. Further, in calculating the pseudo distance cs, data on the speed v and the angle α of the GPS satellite is required. However, by simply replacing the pseudo distance ct at the time of GPS satellite signal reception with the pseudo distance cs at the time of signal transmission, Easy and accurate calculation is possible.

  A measurement point is obtained by performing a positioning calculation of the measurement point O (x, y, z) based on the position A (x, y, z) of the GPS satellite at the time of signal transmission and the calculated pseudo distance cs. It is possible to improve the position detection accuracy at.

  In the flowchart of FIG. 4, step S105 constitutes “position A of the GPS satellite at the time when the signal is generated from the navigation data included in the signal received by the receiver, and time tb. And a navigation data acquisition unit that acquires orbit information including the orbital velocity v and the altitude h.

  Further, the step S106 calculates "the GPS satellite position B at the time tr when the measurement point receives the signal from the acquired orbital velocity v and the time tb from the time difference t = tr-tb. It corresponds to an “elevation angle calculation unit that calculates the first angle α of the horizon with respect to the first line segment connecting the position B and the position O of the measurement point from the distance ct and the altitude h”.

  Further, the step S107 determines that “the position A of the GPS satellite and the position O of the measurement point are based on the distance ct of the first line segment, the first angle α calculated by the elevation angle calculation unit, and the orbital velocity v. This corresponds to a “pseudo distance calculation unit that calculates the distance cs of the second line segment to be connected”.

  Step S111 calculates "the position O of the measurement point from each distance cs (cs1 to cs3) between each position A (A1 to A3) of each calculated GPS satellite and the position O of the measurement point. Corresponds to the “positioning calculation unit”.

  In the above-described embodiment, the pseudo distance is calculated using two inertia systems. However, in practice, the relationship between the GPS satellites 21 to 23 and the measurement points on the ground is a relative circular orbit, so that it becomes a rotational inertia system. Hereinafter, the relationship between the rotational motion of the rotary inertia system and signal transmission will be described with reference to FIG.

In FIG. 5, the relationship between rotational motion and signal transmission as viewed from the K coordinate is shown in FIG. 5 (a), and the relationship between rotational motion and signal transmission as viewed from the Q coordinate is shown in FIG. 5 (b).
In FIG. 5A, when viewed from the K coordinate, the GPS positioning calculation device 10 at the measurement point on the ground moves from the position P to the position O by the angle ωt at time t. In FIG. 5B, when viewed from the Q coordinate, the GPS satellite moves from the position A to the position B at time t by an angle ωt.

  From this, by calculating the following relational expression (13) with the K coordinate, it is possible to calculate the relation between the movement and time in the rotational movement, and also calculating the following relational expression (14) with the Q coordinate. By doing so, it is possible to calculate the relationship between the motion and time in the rotational motion. Here, ω is the relative angular velocity of the GPS positioning calculation device 10 and the GPS satellites 21 to 23 at the ground positioning point, r is the radius of the earth, and R is the radius of the orbit of the GPS satellite.

  Note that since the relationship between ct, cs, and vrt does not change for ellipses and satellites with more complicated orbits, the pseudo distance cs is calculated by drawing the same triangular vector consisting of ct, cs, and vrt. Is possible. Therefore, in calculating the pseudo distance cs in the GPS positioning calculation device 10, except that the calculation unit 14 calculates the relationship between the motion and the time in the rotational motion by the relational expressions (13) and (14) described above. The same operation as in the above-described embodiment is performed.

  As described above, the relationship between the GPS satellites 21 to 23 performing the circular orbit and the measurement point on the ground can be expressed by a rotational inertia system, and the relational expressions (13) and (14) described above regarding the relationship between the rotational motion and time at this time. In the case of taking a more complicated trajectory such as an ellipse, it is possible to calculate the pseudo distance cs with high accuracy without causing an error, as in the above-described embodiment.

  Note that the GPS positioning calculation method of the present invention, for example, as shown in FIG. 1, receives signals transmitted from at least three GPS satellites 21 to 23 and receives measurement points (GPS positioning calculation device 10 on the horizon e). ) Is a GPS positioning method for performing position detection.

  The GPS positioning method includes, for example, a first step to a fourth step as shown in FIG. Here, as in S105, the first step is based on the navigation data included in the signal received by the receiver, and the position A of the GPS satellite, the time tb, and the orbital velocity v at the time when the GPS satellite transmits the signal. And trajectory information including altitude h. Then, the second step calculates the position B of the GPS satellite at the time tr at which the measurement point receives the signal from the time difference t = tr−tb from the acquired orbital velocity v and the time tb as in S106. Then, the first angle α of the horizon with respect to the first line segment connecting the position B of the GPS satellite and the position O of the measurement point is calculated from the distance ct and the altitude h of the first line segment.

  As in S107, the third step measures the position A of the GPS satellite based on the distance ct of the first line segment, the first angle α calculated in S106, and the orbital velocity v acquired in S105. The distance cs of the second line segment connecting the point position O is calculated. In the fourth step, as in S111, the distances cs () between the positions A (A1 to A3) of at least three GPS satellites calculated in the third step and the position O of the measurement point are calculated. The position O of the measurement point is calculated from cs1 to cs3).

  According to the GPS positioning method of the present invention, the position of a measurement point can be detected with extremely high accuracy. According to the GPS positioning method of the present invention, in order to calculate the pseudo distance cs, information on the speed v and the angle α of the GPS satellite is necessary. Conventionally, ct used as the pseudo distance is simply replaced with cs. A simple calculation with high accuracy is possible. Similarly, in the case of a circular orbit, it is possible to calculate a pseudo distance with high accuracy without causing an error.

  Furthermore, the GPS positioning method of the present invention is a calculation method that can take elevation angle-dependent characteristics into consideration, and this can greatly improve the calculation accuracy of the pseudorange. If the calculation accuracy of the pseudo distance is improved, the accuracy of the position detection of the measurement point is consequently greatly improved. In addition, industrial effects such as simplification of the calculation method and reduction of the number of GPS satellites used are extremely large.

  The GPS positioning calculation apparatus of the present invention is not limited to a car navigation system, but can be used for detecting the position of a moving body that is a measurement point, such as a ship, an aircraft, a work vehicle, or a portable terminal. Further, if a method such as estimating a pseudo-range error from the differential data is adopted, the accuracy can be further improved. In addition to position detection, atmospheric delay, ionospheric delay, and the like can be calculated with high accuracy, so a dramatic improvement in weather observation can be expected.

  DESCRIPTION OF SYMBOLS 10 ... GPS positioning calculating apparatus, 11 ... Receiver, 11a ... Antenna, 11b ... RF circuit, 12 ... A / D converter, 13 ... Correlator, 14 ... Calculator, 15 ... Control part, 16 ... Memory | storage part, 21 -23 GPS satellite.

Claims (7)

A GPS positioning calculation method in which a signal transmitted from at least three GPS satellites is received by a receiver, and a calculator calculates the position of a measurement point on the horizon based on the signal,
Orbit information including the position A of the GPS satellite, the time tb, the orbital velocity v, and the altitude h from the navigation data included in the signal received by the receiver. A first step by which the computing unit obtains:
The computing unit is
From the acquired orbital velocity v and time tb, the position B of the GPS satellite at the time tr when the measurement point receives the signal is calculated from the time difference t = tr−tb. A second step of calculating a first angle α of the horizon with respect to a first line connecting the position O of the measurement point from a distance ct and an altitude h of the first line;
Based on the distance ct of the first line segment, the first angle α calculated in the second step, and the orbital velocity v, the position A of the GPS satellite and the position O of the measurement point are connected. A third step of calculating a distance cs of the second line segment;
A fourth step of calculating the position O of the measurement point from the respective distances cs between the position A of the at least three GPS satellites calculated in the third step and the position O of the measurement point;
A GPS positioning calculation method characterized by comprising: The second step includes
From the calculated first angle α and the orbital velocity v of the GPS satellite acquired in the first step, the position A of the GPS satellite and the current location O of the measurement point when the signal is generated The GPS positioning calculation method according to claim 1, wherein the second angle β of the horizon with respect to a second line segment connecting the two is calculated. The second step includes
3. The GPS positioning calculation method according to claim 1, wherein the following angular relational expression (101) is calculated when calculating the first angle α or the second angle β.

The third step includes
The GPS positioning calculation method according to claim 1, wherein the following relational expression (102) is calculated in calculating the distance cs of the second line segment.

The third step includes
2. The GPS positioning calculation method according to claim 1, wherein, in calculating the distance cs of the second line segment, the following relational expressions (103) and (104) are calculated to calculate the speed in the rotational motion. .

The fourth step includes
The GPS positioning calculation method according to claim 1, wherein the following relational expression (105) is calculated in calculating the position O of the measurement point.

A receiver for receiving signals emitted from at least three GPS satellites, and a computing unit for calculating a position O of a measurement point on the horizon,
Navigation data acquisition for acquiring orbit information including a position A, a time tb, an orbital velocity v, and an altitude h of the GPS satellite at the time of emitting the signal from the navigation data included in the received signal. And
From the acquired orbital velocity v and time tb, the position B of the GPS satellite at the time tr when the measurement point receives the signal is calculated from the time difference t = tr−tb. An elevation angle calculation unit that calculates a first angle α of the horizon with respect to a first line segment connecting the position O of the measurement point from a distance ct and an altitude h of the first line segment;
Based on the distance ct of the first line segment, the first angle α calculated by the elevation angle calculation unit, and the orbital velocity v, the position A of the GPS satellite and the position O of the measurement point are connected. A pseudo distance calculation unit for calculating a distance cs of the two line segments;
Positioning for calculating the position O of the measurement point from the distance cs of each second line segment between the position A of each of the GPS satellites and the position O of the measurement point calculated by the pseudo distance calculation unit. An arithmetic unit;
A GPS positioning calculation device comprising:

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