JP6152663B2 - Method for controlling position calculation apparatus and position calculation apparatus - Google Patents

Description

  The present invention relates to a control method for a position calculation device and the like.

  A GPS (Global Positioning System) is widely known as a position calculation system using a positioning signal from a positioning satellite. In GPS, orbit information (ephemeris and almanac) superimposed on a GPS satellite signal is acquired, the position of the satellite is specified, and the position is calculated based on the pseudorange.

  Since the ephemeris is not held at the time of the initial position calculation, it is necessary to acquire the ephemeris first. However, since this takes about several tens of seconds, the initial position calculation time (TTFF: Time to First Fix) is Increase.

  Therefore, in order to shorten the initial position calculation time, there is a method of predicting the locus of a GPS satellite and calculating satellite orbit information corresponding to the ephemeris. However, calculation of this satellite orbit information requires information such as the position and velocity of the GPS satellite. For example, positioning such as the Quasi-Zenith Satellites (QZS) described in Non-Patent Document 1 is required. A method of transmitting information necessary for calculating satellite orbit information from a satellite for use can be considered.

Quasi-Zenith Satellite System User Interface Specification, IS-QZSS Ver. 1.3, June 22, 2011, p. 79-101

  However, more accurate satellite orbit information can be calculated by using high-resolution information. However, since the amount of data that can be transmitted from the quasi-zenith satellite is limited, it can be transmitted from the quasi-zenith satellite. There is a limit to the resolution of information necessary for calculating satellite orbit information. Therefore, if the information necessary for satellite orbit information is acquired from the quasi-zenith satellite, the accuracy of the calculated satellite orbit information is limited.

  The present invention has been made in view of the above problems, and an object thereof is to calculate more accurate satellite orbit information in position calculation using satellite signals from positioning satellites.

  According to a first aspect of the present invention, the first positioning support information is received from a first transmission source that transmits the first positioning support information that is a basis for calculating the orbit information of the positioning satellite. And, when reception of the first positioning support information is successful, calculating first trajectory information using the first positioning support information, and receiving the first positioning support information If the second positioning support information is attempted to be received from the second transmission source that transmits the second positioning support information that is less accurate than the first positioning support information. When the positioning support information is successfully received, the second trajectory information is calculated using the second positioning support information, and at least one of the first trajectory information and the second trajectory information Orbital information and satellite signals from the positioning satellite And calculating a position, a control method of the position calculating device including a.

  As another invention, a signal from the first transmission source that transmits the first positioning support information that is a basis for calculating the orbit information of the positioning satellite, and a first signal that is less accurate than the first positioning support information. A position calculation device capable of receiving a signal from a second transmission source that transmits the second positioning support information, and attempts to receive the first positioning support information; and When the reception is successful, the first positioning support information is used to calculate the first trajectory information, and when the reception of the first positioning support information fails, the second positioning support information When the second positioning support information is successfully received, calculating the second trajectory information using the second positioning support information, and the first trajectory information and Of the second orbit information, at least one of the orbit information and the And calculating the position using satellite signals from position satellite, it is also possible to configure the position calculating device for execution.

  According to the first invention and the like, first, the first positioning support information is tried to be received from the first transmission source. And when reception of 1st positioning assistance information fails, reception of 2nd positioning assistance information is tried from the 2nd transmission source of lower precision than 1st positioning assistance information. That is, priority is given to receiving the first positioning support information with higher accuracy than the second positioning support information. Therefore, it is possible to calculate more accurate trajectory information. In addition, when the reception of the first positioning support information fails, the reception of the second positioning support information is attempted. Then, when the second positioning support information is successfully received, the trajectory information is calculated from the second positioning support information. Thereby, even when the first positioning support information cannot be acquired, the trajectory information can be calculated from the second positioning support information.

  As a second invention, a signal carrying the orbit information over a predetermined carrying time is superimposed on the satellite signal in the control method of the first invention, and the first transmission source is The first positioning support information is transmitted in a shorter time than the transport time, and the second transmission source transmits the second positioning support information in a shorter time than the transport time, and the first positioning support information The reception of information receives the first positioning support information in a shorter time than acquiring the orbit information from the satellite signal, and the reception of the second positioning support information receives the orbit information from the satellite signal. A control method for receiving the second positioning support information in a shorter time than the acquisition may be configured.

  According to the second aspect of the invention, the first transmission source and the second transmission source transmit the first positioning support information and the second positioning support information in a shorter time than the carrying time in which the satellite signal carries the orbit information. Send each one. In other words, it is possible to receive the first positioning support information and the second positioning support information in a shorter time than acquiring the orbit information from the satellite signal. Therefore, position calculation can be started more quickly than when satellite signals are received.

  According to a third aspect of the invention, there is provided a control method in which the first positioning support information in the control method of the first or second invention is information having a larger number of significant digits than the second positioning support information. It is good to do.

  According to the third aspect of the invention, the first positioning support information is information having a larger number of significant digits than the second positioning support information. Therefore, information with higher accuracy than the second positioning support information is provided. It is possible to transmit from one transmission source.

  As a fourth invention, in the control method according to any one of the first to third inventions, when reception of the second positioning support information fails, the satellite signal is superimposed on the satellite signal. It is good also as comprising the control method which further includes acquiring the orbit information which exists.

  According to the fourth aspect of the invention, when the reception of the second positioning support information fails, the orbit information superimposed on the satellite signal is acquired from the satellite signal. Thus, even when the second positioning support information cannot be acquired, the position can be calculated using the orbit information acquired from the satellite signal.

  Further, as a fifth invention, calculating the position in the control method according to any one of the first to fourth inventions comprises calculating a reference date and time of the first trajectory information and a reference date and time of the second trajectory information. It is good also as configuring a control method including selecting trajectory information used for position calculation with reference.

  According to the fifth aspect, the trajectory information used for position calculation is selected with reference to the reference date and time of the first trajectory information and the reference date and time of the second trajectory information. For example, by selecting the trajectory information with a new reference date and time, the position can be calculated using the newer trajectory information.

  Further, as a sixth invention, selecting the trajectory information in the control method of the fifth invention uses a difference between a reference date and time of the first trajectory information and a reference date and time of the second trajectory information. A control method including selecting trajectory information used for position calculation may be configured.

  According to the sixth aspect, the trajectory information used for position calculation is selected using the difference between the reference date and time of the first trajectory information and the reference date and time of the second trajectory information. For example, even if the reference date and time of the first trajectory information is older than the reference date and time of the second trajectory information, the first trajectory information if the difference between the reference dates and times is within a predetermined time. By selecting, the position can be calculated using more accurate trajectory information.

  Further, as a seventh invention, the first and second positioning support information in the control method of any one of the first to sixth inventions includes information on the position and velocity of the positioning satellite. Calculating the first orbit information using the equation of motion representing the motion of the satellite orbiting the earth and the position and velocity of the positioning satellite included in the first positioning support information, Calculating the first orbit information, wherein calculating the second orbit information uses the equation of motion and the position and velocity of the positioning satellite included in the second positioning support information. Then, a control method including calculating the second trajectory information may be configured.

  According to the seventh aspect of the invention, the first orbit information is obtained by using the equation of motion representing the motion of the satellite orbiting the earth and the position and velocity of the positioning satellite included in the first positioning support information. It can be calculated appropriately. The same applies to the second trajectory information.

The figure which shows an example of the system configuration | structure of a position calculation system. The figure which shows an example of a function structure of a baseband process circuit part. The figure which shows an example of the table structure of the table for flag setting. The flowchart which shows the flow of a position calculation process. The flowchart which shows the flow of a positioning assistance information acquisition process.

  Hereinafter, an example of a preferred embodiment to which the present invention is applied will be described with reference to the drawings. This embodiment is an embodiment in which GPS (Global Positioning System) is applied as a satellite positioning system. However, it is needless to say that embodiments to which the present invention is applicable are not limited to the embodiments described below.

1. System Configuration FIG. 1 is a diagram illustrating an example of a system configuration of a position calculation system in the present embodiment.
The position calculation system includes a position calculation device 1, a GPS satellite 3, an IMES (Indoor Messaging System) transmitter 5, and a quasi-zenith satellite 7.

  The GPS satellite 3 is a kind of positioning satellite, and transmits a navigation message including orbit information such as almanac and ephemeris on a GPS satellite signal which is a kind of positioning signal. The GPS satellite signal is a 1.57542 [GHz] communication signal modulated by a CDMA (Code Division Multiple Access) method known as a spread spectrum method by a C / A (Coarse and Acquisition) code which is a kind of spreading code. is there. The C / A code is a pseudo random noise code having a repetition period of 1 ms with a code length of 1023 chips as one PN frame, and is a code unique to each GPS satellite 3.

  The IMES transmitter 5 is a type of ground communication device, and transmits first positioning support information that is information for supporting positioning by the position calculation device 1. The IMES transmitter 5 is installed in various facilities / buildings such as shopping malls, underground malls, airports, movie theaters, and hotels. A PRN code different from that of the GPS satellite 3 is assigned to the IMES transmitter 5, and the first positioning support information is transmitted by the same spread spectrum method as that of the GPS satellite 3 using the assigned PRN code. . At this time, the IMES transmitter 5 transmits the first positioning support information in a shorter time than the transport time in which the GPS satellite signal transports the ephemeris. The IMES transmitter 5 corresponds to a first transmission source.

  The first positioning support information transmitted from the IMES transmitter 5 is information serving as a basis for calculating orbit information (more specifically, ephemeris) of the GPS satellite 3. In the present embodiment, the first positioning support information includes satellite position speed information of each GPS satellite 3, a reference date and time, and an Earth Orientation Parameter (EOP).

  The satellite position speed information includes the satellite position r0 and the satellite speed v0 at the reference date and time t0 of each GPS satellite 3 and a clock error. In addition, the earth attitude parameters that are earth attitude information are UT1-UTC, length of day (LOD), X-pole motion, X-pole motion speed, Y-pole motion, and Y-pole motion speed. Contains.

  The IMES transmitter 5 is controlled by a management server (not shown) so as to update and transmit the first positioning support information at regular timing. Specifically, the management server periodically acquires the latest ephemeris of the GPS satellite 3 from, for example, GNSS (Global Navigation Satellite System) base stations installed around the world. When the ephemeris is acquired from the GNSS base station, the satellite position r0 and the satellite velocity v0 at the reference date and time t0 are calculated using the values of the satellite orbit parameters included in the ephemeris. Then, control is performed so as to generate first positioning support information in which the satellite position speed information, clock error information, reference date and time, and EOP are collected and transmitted from the IMES transmitter 5. The reference date and time may be, for example, time information when the management server acquires the ephemeris from the GNSS base station, or may be time information at the beginning of the acquired effective period of the ephemeris. In any case, the information represents the new or old of the ephemeris.

  The quasi-zenith satellite 7 is a kind of artificial satellite and is a satellite of the quasi-zenith satellite system plan known as a Japanese satellite positioning system. In the present embodiment, the quasi-zenith satellite 7 receives the second positioning support information that is information for supporting the positioning by the position calculation device 1 as a message superimposed on the L1-SAIF signal that is the submeter class reinforcement signal. Send. The PZN code different from that of the GPS satellite 3 and the IMES transmitter 5 is assigned to the quasi-zenith satellite 7, and the second positioning is performed by the same spread spectrum method as that of the GPS satellite 3 using the assigned PRN code. Send support information. At this time, the quasi-zenith satellite 7 transmits the second positioning support information in a shorter time than the transport time in which the GPS satellite signal transports the ephemeris. The quasi-zenith satellite 7 corresponds to a second transmission source.

  The quasi-zenith satellite 7 is managed by a control control station (not shown), and is configured to update and transmit the second positioning support information at regular timing. That is, as with the IMES transmitter 5 described above, the satellite position speed information and the reference date and time information transmitted from the quasi-zenith satellite 7 are periodically updated, and new second positioning support information is transmitted to the broadcast at any time. The

Here, the resolution of the value regarding the “velocity” of the GPS satellite 3 that can be transmitted from the quasi-zenith satellite 7 in the second positioning support information is about 0.001 = 10 ⁻³ [m / s]. If this is considered as a speed error, a simple calculation results in an error of 0.001 × 4 × 3600 = 14 [m] when a satellite orbit of 4 hours is predicted. When estimating the satellite orbit for a long period of time to some extent, it is ideal that the accuracy of the “velocity” is about 10 ⁻⁶ to 10 ⁻⁷ [m / s].

Therefore, in the present embodiment, the management server controls the IMES transmitter 5 to transmit the first positioning support information including speed information with accuracy of 10 ⁻⁶ [m / s], and the control control station A description will be given assuming that the second positioning support information including the speed information with accuracy of 10 ⁻³ [m / s] is transmitted from the quasi-zenith satellite 7. That is, regarding satellite speed information, the first positioning support information will be described as storing information having a larger number of effective digits than the second positioning support information.

2. Principle of Ephemeris Calculation (Prediction) The position calculation device 1 uses the first positioning support information received from the IMES transmitter 5 or the second positioning support information received from the quasi-zenith satellite 7. The principle of calculating (predicting) the ephemeris will be described.

  The first positioning support information and the second positioning support information include satellite position speed information (position and speed information) of each GPS satellite 3, a reference date and time, and an earth attitude parameter (EOP). Yes. Using these pieces of information, the satellite orbit of each GPS satellite 3 is calculated (predicted). The satellite orbit calculation method is the same when the first positioning support information is used and when the second positioning support information is used.

上式（１）において、ｍはＧＰＳ衛星３の質量、ＦはＧＰＳ衛星３に作用する力、ｒは時刻ｔにおけるＧＰＳ衛星３の位置、である。また、ａは、ＧＰＳ衛星３に作用する加速力であり、次式（２）で与えられる。

上式（２）において、ａ_ｇは重力加速度、ａ_ｍｏｏｎは月の引力、ａ_ｓｕｎは太陽の引力、ａ_ｓｒｇは太陽輻射圧、である。すなわち、式（１）と式（２）により、宇宙空間における地球を周回する衛星の運動を表わす運動方程式が決まる。 First, the equation of motion of the following equation (1) is established for the GPS satellite 3.

In the above formula (1), m is the mass of the GPS satellite 3, F is the force acting on the GPS satellite 3, and r is the position of the GPS satellite 3 at time t. Further, a is an acceleration force acting on the GPS satellite 3, and is given by the following equation (2).

In the above formula (2), _{a g} is the gravitational _{acceleration, a moon} is attraction of the _moon, are _{a sun} attraction of the _{sun, a srg} is solar radiation pressure. That is, equation (1) and equation (2) determine the equation of motion representing the motion of the satellite orbiting the earth in outer space.

ここで与える初期値を、第１の測位支援情報又は第２の測位支援情報に含まれる、基準日時ｔ０におけるＧＰＳ衛星３の衛星位置ｒ０及び衛星速度ｖ０とする。衛星軌道が求められると、この衛星軌道に適合するエフェメリスを算出することができる。 For the equation of motion of equation (1), GPS integration at time t is performed by performing numerical integration with satellite position r (t0) = r0 at time t0 and satellite velocity v (t0) = v0 as initial values. The satellite position r (t) of the satellite 3, that is, the orbit function indicating the satellite orbit is obtained as the following equation (3).

The initial values given here are the satellite position r0 and the satellite velocity v0 of the GPS satellite 3 at the reference date and time t0, which are included in the first positioning support information or the second positioning support information. When a satellite orbit is obtained, an ephemeris that matches the satellite orbit can be calculated.

  The position calculation device 1 can also estimate an ephemeris having a valid period equal to the broadcast ephemeris broadcast from the GPS satellite 3 based on the above principle, or an ephemeris having a longer valid period than the broadcast ephemeris ( (Hereinafter referred to as “long-term prediction femeris”).

  By the way, the above equation of motion (Equation (1)) representing the motion of the satellite is defined in the Earth Centered Inertial (ECI) coordinate system which is an inertial coordinate system based on the earth center. On the other hand, the position calculated by the position calculation device 1 and the position and velocity of the GPS satellite 3 included in the positioning support information are based on the earth center and are fixed to the earth. Fixed: defined in the ECEF) coordinate system.

式（４）において、Ａは極運動の回転行列、Ｂは恒星時の回転行列、Ｃは章動の回転行列、Ｄは歳差の回転行列、を表す。これらの行列Ａ，Ｂ，Ｃ，Ｄは、時刻ｔと、測位支援情報に含まれる地球姿勢パラメーター（ＥＯＰ）とによって決まる。換言すると、地球姿勢パラメーターによってこれらの行列Ａ，Ｂ，Ｃ，Ｄが示され、座標変換行列Ｑが決まるとも言える。 For this reason, when calculating the satellite orbit, coordinate conversion between the earth center inertia (ECI) coordinate system and the earth center earth fixed (ECEF) coordinate system is necessary. As is well known, the coordinate transformation matrix Q between the earth center inertia (ECI) coordinate system and the earth center earth fixed (ECEF) coordinate system is given by the following equation (4).

In Equation (4), A represents a polar motion rotation matrix, B represents a stellar rotation matrix, C represents a nutation rotation matrix, and D represents a precession rotation matrix. These matrices A, B, C, and D are determined by time t and the earth attitude parameter (EOP) included in the positioning support information. In other words, it can be said that these matrixes A, B, C, and D are indicated by the earth attitude parameter, and the coordinate transformation matrix Q is determined.

3. Configuration of Position Calculation Device FIG. 1 is a block diagram illustrating an example of a functional configuration of the position calculation device 1.
The position calculation device 1 includes an antenna 10, a receiving unit 20, a host processing unit 30, an operation unit 31, a display unit 32, a sound output unit 33, a clock unit 34, and a storage unit 35. Is done.

  The antenna 10 is an RF (Radio Frequency) signal including a GPS satellite signal transmitted from the GPS satellite 3, an IMES signal transmitted from the IMES transmitter 5, and a quasi-zenith satellite signal transmitted from the quasi-zenith satellite 7. Is an antenna for receiving the signal.

  The receiving unit 20 includes an RF receiving circuit unit 21 and a baseband processing circuit unit 22. For example, a navigation message including an ephemeris is acquired from a GPS satellite signal received by the antenna 10, first positioning support information is acquired from an IMES signal, or second positioning support information is acquired from a quasi-zenith satellite signal. Process such as.

  The first positioning support information and the second positioning support information have a smaller data amount than the ephemeris carried by the GPS satellite signal. For this reason, in the reception of the first positioning support information and the second positioning support information, the reception is completed in a shorter time than acquiring the ephemeris from the GPS satellite signal.

  In the present embodiment, when the first positioning support information is attempted to be received from the IMES transmitter 5 and the first positioning support information is successfully received, the first ephemeris is obtained using the first positioning support information. calculate. In addition, when the reception of the first positioning support information fails, the second positioning support information is tried to be received from the quasi-zenith satellite 7, and when the second positioning support information is successfully received, the second positioning support information is received. A second ephemeris is calculated using the positioning support information. Then, one ephemeris is selected from the first ephemeris and the second ephemeris, and the position is calculated using the one ephemeris and the GPS satellite signal from the GPS satellite 3. It is also possible to use both ephemeris for position calculation instead of one of the first ephemeris and the second ephemeris. That is, the position may be calculated using at least one of the first orbit information and the second orbit information and the satellite signal from the positioning satellite.

  The RF receiving circuit unit 21 and the baseband processing circuit unit 22 can be manufactured as separate LSIs (Large Scale Integration) or can be manufactured as one chip.

  The RF receiving circuit unit 21 is an RF signal receiving circuit. As a circuit configuration, for example, an RF signal received by the antenna 10 may be converted into a digital signal by an A / D converter to process the digital signal, or an RF signal received by the antenna 10 may be processed. The digital signal may be output to the baseband processing circuit unit 22 by performing signal processing with the analog signal and finally performing A / D conversion.

  In the latter case, for example, the RF receiving circuit unit 21 can be configured as follows. That is, an oscillation signal for RF signal multiplication is generated by dividing or multiplying a predetermined oscillation signal. Then, by multiplying the generated oscillation signal by the RF signal output from the antenna 10, the RF signal is down-converted to an intermediate frequency signal (hereinafter referred to as IF (Intermediate Frequency) signal), and the IF signal is amplified. Thereafter, the signal is converted into a digital signal by an A / D converter and output to the baseband processing circuit unit 22.

  The baseband processing circuit unit 22 captures a signal by performing carrier removal, correlation processing, and the like on the signal output from the RF receiving circuit unit 21. Successful acquisition means successful signal reception. If acquisition is successful, the information (data; bit value) carried in the signal is decoded. The IMES signal and the quasi-zenith satellite signal are signals modulated by the same frequency and the same modulation method as the GPS satellite signal, except for the PRN code. Therefore, the receiving unit 20 can receive (capture) only the PRN code when receiving any of the GPS satellite signal, the IMES signal, and the quasi-zenith satellite signal.

  When receiving a satellite signal from the GPS satellite 3, the baseband processing circuit unit 22 uses the satellite signal and various ephemeris stored in the storage unit 200 to determine the position (position) of the position calculation device 1. Coordinates) and clock error (clock bias).

  The host processing unit 30 is realized by an arithmetic device such as a CPU (Central Processing Unit), for example, and comprehensively controls each unit of the position calculation device 1 according to various programs such as a system program stored in the storage unit 35. . For example, based on the position coordinates acquired from the baseband processing circuit unit 22, a map indicating the current position is displayed on the display unit 32, or the position coordinates are used for various application processes.

  The operation unit 31 is an input device such as a touch panel or a button switch, and outputs an operation signal corresponding to the performed operation to the host processing unit 30. By operating the operation unit 31, various instructions such as a position calculation request are input.

  The display unit 32 is a display device such as an LCD, and performs various displays based on a display signal input from the host processing unit 30.

  The sound output unit 33 is a sound output device such as a speaker, for example, and outputs various sounds based on an audio signal input from the host processing unit 30.

  The clock unit 34 is an internal clock of the position calculation device 1 and includes a crystal oscillator including a crystal resonator and an oscillation circuit.

  The storage unit 35 is realized by a storage device such as a ROM (Read Only Memory), a flash ROM, or a RAM (Random Access Memory), for example, and a system program for the host processing unit 30 to control the position calculation device 1 in an integrated manner. Various programs and data for executing various application processes are stored.

  FIG. 2 is a functional configuration diagram of the baseband processing circuit unit 22. The baseband processing circuit unit 22 includes a processing unit 100 and a storage unit 200.

  The processing unit 100 is realized by an arithmetic circuit such as a CPU or a DSP (Digital Signal Processor), for example, and performs overall control of the baseband processing circuit unit 22 based on programs, data, and the like stored in the storage unit 200.

  The processing unit 100 includes a GPS satellite signal capturing unit 110, a coordinate transformation matrix generation unit 120, a first ephemeris calculation unit 130, a second ephemeris calculation unit 140, and a position calculation unit 150 as main functional units. As a functional part. However, these functional units are only described as one embodiment, and all of these functional units do not necessarily have to be essential components. Of course, functional units other than these may be added as essential components.

  The GPS satellite signal acquisition unit 110 acquires a GPS satellite signal. That is, the GPS satellite 3 is captured by performing a correlation operation using the replica code of the PRN code assigned to the GPS satellite 3 on the signal output from the RF receiving circuit unit 21. Then, the carrier is removed from the captured GPS satellite signal, the navigation message carried in the GPS satellite signal is demodulated, and the ephemeris included in the navigation message is acquired. The acquired ephemeris is stored in the individual satellite information 250 as a received ephemeris.

  The coordinate transformation matrix generation unit 120 uses the earth attitude parameter (EOP) included in the first positioning support information or the second positioning support information, and the earth center inertia ( The coordinate transformation matrix Q between the ECI) coordinate system and the earth center earth fixed (ECEF) coordinate system is calculated.

  The first ephemeris calculation unit 130 calculates the first ephemeris of each GPS satellite 3 based on the first positioning support information received from the IMES transmitter 5. The calculation of the first ephemeris can be realized according to the above principle using the satellite position, the satellite speed, and the reference date / time included in the first positioning support information.

  The second ephemeris calculating unit 140 calculates the second ephemeris of each GPS satellite 3 based on the second positioning support information received from the quasi-zenith satellite 7. The calculation of the second ephemeris can be realized according to the above principle using the satellite position, the satellite speed, and the reference date / time included in the second positioning support information.

  More specifically, using the coordinate transformation matrix Q generated by the coordinate transformation matrix generator 120, the satellite position r0 and the satellite velocity v0 of the GPS satellite 3 included in the positioning support information are fixed to the Earth Centered Earth (ECEF). Convert from coordinate system to Earth Centered Inertia (ECI) coordinate system.

  Next, numerical integration is performed on the orbit function r (t) of Equation (3) described above using the satellite position r0 and the satellite velocity v0 after coordinate conversion as initial values to obtain an orbit function r (t ) Then, an ephemeris that matches the satellite orbit represented by the orbit function r (t) is calculated. The ephemeris is calculated by, for example, a numerical calculation (for example, a least square method) that minimizes a difference between a satellite orbit based on a predetermined ephemeris parameter value and a satellite orbit represented by an orbit function r (t). it can. However, it goes without saying that other methods may be used.

  The position calculation unit 150 calculates the position of the position calculation device 1. Specifically, using the ephemeris and measurement information of each captured satellite stored in the storage unit 200, for example, a known position calculation based on a least square method or a Kalman filter algorithm is performed, and the position of the position calculation device 1 Calculate the clock error.

  The storage unit 200 is realized by a storage device such as a ROM, a flash ROM, or a RAM, and a system program for the processing unit 100 to control the baseband processing circuit unit 22 in an integrated manner, a program for realizing various functions, Data etc. are memorized. Further, calculation results used as a work area of the processing unit 100 and executed by the processing unit 100 according to various programs are temporarily stored.

  In the present embodiment, the storage unit 200 stores a position calculation program 210, a flag setting table 220, first positioning support information 230, second positioning support information 240, individual satellite information 250, and calculation results. Data 260 is stored.

  The position calculation program 210 is a program that is read by the processing unit 100 and executed as a position calculation process (see FIG. 4). The position calculation program 210 includes a positioning support information acquisition program 211 executed as positioning support information acquisition processing (see FIG. 5) as a subroutine. These processes will be described later in detail using a flowchart.

  The flag setting table 220 is a table for setting a flag for determining which ephemeris of the first ephemeris and the second ephemeris is used for position calculation, and an example of the table configuration is shown in FIG. Shown in

  In the flag setting table 220, a condition No. 221 indicating a condition number, a condition content 223 indicating a specific content of the condition, and a flag 225 set when the condition is satisfied are defined in association with each other. .

  The first condition is “the elapsed time from the reference date and time of the first ephemeris has reached the first threshold time, and the elapsed time from the reference date and time of the second ephemeris is the second threshold time. Has been reached. In this case, “no setting” is set for the flag. The first threshold time and the second threshold time may be the same time or different times. The flag “no setting” means that neither the first ephemeris nor the second ephemeris is used for position calculation.

  This first condition is that a fixed time has elapsed from the reference date and time of the first ephemeris 252 stored in the storage unit 200 and the reference of the second ephemeris 253 stored in the storage unit 200. When a certain time has passed since the date and time, it indicates that neither the first ephemeris 252 nor the second ephemeris 253 is used for position calculation. That is, in this case, the navigation message is demodulated from the GPS satellite signal to obtain the reception ephemeris 254, and the position is calculated using this.

  The second condition defines that “the reference date and time of the first ephemeris is newer than the reference date and time of the second ephemeris”. Further, “first” is defined as the flag in this case. This indicates that when the reference date and time of the first ephemeris 252 stored in the storage unit 200 is newer than the reference date and time of the second ephemeris 253, the first ephemeris 252 is used for position calculation. .

  The third condition defines that “the reference date and time of the second ephemeris is newer than the reference date and time of the first ephemeris”. In addition, when this condition is satisfied, two more conditions are set. Specifically, “first” is set as a flag when the condition “the difference between the reference dates of two ephemeris is within a predetermined time” is satisfied, and “the difference between the reference dates of two ephemeris exceeds a predetermined time”. "Second" is defined as a flag when the condition "is satisfied.

  Even if the reference date and time of the second ephemeris 253 stored in the storage unit 200 is newer than the reference date and time of the first ephemeris 252, if the time difference between the reference dates and times is within a predetermined time, It shows that the first ephemeris 252 is preferentially selected and used for position calculation. If the reference date and time of the second ephemeris 253 is newer than the reference date and time of the first ephemeris 252 and the time difference between the reference dates and times exceeds a predetermined time, the second ephemeris 253 is positioned. It is used for calculation.

  The trajectory information used for position calculation is selected with reference to the reference date and time of the first ephemeris (first trajectory information) and the reference date and time of the second ephemeris (second trajectory information). Further, according to the third condition, the position is calculated using the difference between the reference date and time of the first ephemeris (first trajectory information) and the reference date and time of the second ephemeris (second trajectory information). The trajectory information to be used is selected.

  The first positioning support information 230 includes satellite-specific information 231, a reference date and time 232, and an earth attitude parameter (EOP) 233. The satellite-specific information 231 is individual information for each GPS satellite 3, and includes satellite number 231A, satellite position information 231B, satellite speed information 231C, and satellite clock error information 231D.

  The type of information included in the second positioning support information 240 is the same as that of the first positioning support information 230. However, in the second positioning support information 240, the accuracy of the satellite speed information is lower than that of the first positioning support information 230 as described above.

  The individual satellite information 250 is individual information of each GPS satellite 3 and is information generated for each GPS satellite 3. The individual satellite information 250 includes a satellite number 251, a first ephemeris 252, a second ephemeris 253, a received ephemeris 254, and measurement information 255.

  The first ephemeris 252 is an ephemeris calculated using the first positioning support information 230, and the second ephemeris 253 is an ephemeris calculated using the second positioning support information 240. The reception ephemeris 254 is an ephemeris obtained by demodulating a GPS satellite signal.

  The measurement information 255 is data of various quantities (for example, code phase and Doppler frequency) related to GPS satellite signals obtained by performing so-called phase search and frequency search.

  The calculation result data 260 is data in which a position (position coordinates) and a clock error (clock bias) calculated by the position calculation unit 150 performing a position calculation process are stored.

4). Processing Flow FIG. 4 is a flowchart for explaining the flow of position calculation processing executed by the processing unit 100 in accordance with the position calculation program 210 stored in the storage unit 200. This position calculation process is a process executed when, for example, a position calculation execution instruction operation is performed by the user via the operation unit 31.

  First, the processing unit 100 performs a positioning support information acquisition process according to the positioning support information acquisition program 211 stored in the storage unit 200 (step A1).

FIG. 5 is a flowchart showing the flow of the positioning support information acquisition process.
First, the processing unit 100 attempts to receive an IMES signal from the IMES transmitter 5 (step B1). Specifically, the correlation calculation with the received signal is performed using the replica code of the PRN number assigned to the IMES transmitter 5, and if the correlation is obtained, it is determined that the reception is successful. If the reception is successful (step B3; Yes), a demodulation process for demodulating the first positioning support information 230 from the received IMES signal is performed (step B5).

  Next, the processing unit 100 determines whether or not to update the first positioning support information 230 (step B7). Specifically, the reference date / time 232 included in the demodulated first positioning support information 230 and the reference date / time 232 included in the first positioning support information 230 stored in the storage unit 200 are compared. Then, when the reference date and time 232 included in the demodulated first positioning support information 230 is newer, it is determined that the first positioning support information 230 is updated.

  If it determines with not updating (step B7; No), the process part 100 will set the setting of a flag with the setting in the last process, and will complete | finish a positioning assistance information acquisition process. On the other hand, if it determines with updating (step B7; Yes), the process part 100 will update and memorize | store the demodulated 1st positioning assistance information 230 in the memory | storage part 200 (step B9).

  After that, the coordinate transformation matrix generation unit 120 uses the earth attitude parameter (EOP) 233 included in the first positioning support information 230 stored in the storage unit 200 to use the earth center inertia (ECI) coordinate system and the earth center earth. A coordinate transformation matrix Q with a fixed (ECEF) coordinate system is generated (step B11).

  Next, the first ephemeris calculation unit 130 performs a first ephemeris calculation process for each GPS satellite 3 (step B13). Specifically, the satellite position r0 and the satellite velocity v0 of the corresponding GPS satellite 3 included in the first positioning support information 230 are coordinate-transformed using the coordinate transformation matrix Q. Then, a motion equation for the GPS satellite 3 is generated, and numerical integration using the satellite position r0 and satellite velocity v0 after coordinate conversion as initial values is performed on the motion equation, thereby predicting the GPS satellite 3. Predict satellite orbit. Then, the first ephemeris 252 is calculated by obtaining the ephemeris parameters based on the predicted satellite orbit.

  Next, the processing unit 100 updates and stores the first ephemeris 252 stored in the individual satellite information 250 of the storage unit 200 for each GPS satellite 3 (step B15).

  Thereafter, the processing unit 100 performs a flag setting process (step B17). Specifically, with reference to the flag setting table 220 stored in the storage unit 200, it is determined which condition content 223 is satisfied in order from the first condition. The flag 225 associated with the condition No. 221 of the established condition content 223 is set. Thereafter, the processing unit 100 ends the positioning support information acquisition process.

  On the other hand, if it is determined in step B3 that reception of the IMES signal has failed (step B3; No), the processing unit 100 attempts to receive a quasi-zenith satellite signal (step B19). Specifically, the correlation calculation with the received signal is performed using the replica code of the PRN number assigned to the quasi-zenith satellite 7, and if the correlation is obtained, it is determined that the reception is successful. If the reception is successful (step B21; Yes), the processing unit 100 performs a demodulation process of demodulating the second positioning support information 240 from the received quasi-zenith satellite signal (step B23).

  Next, the processing unit 100 determines whether or not to update the second positioning support information 240 (step B25). Specifically, the reference date / time 242 included in the demodulated second positioning support information 240 is compared with the reference date / time 242 included in the second positioning support information 240 stored in the storage unit 200. Then, when the reference date and time 242 included in the demodulated second positioning support information 240 is newer, it is determined that the second positioning support information 240 is updated.

  If it determines with not updating (step B25; No), the process part 100 will set the setting of a flag as it was in the last process, and will complete | finish a positioning assistance information acquisition process. On the other hand, if it determines with updating (step B25; Yes), the process part 100 will update-store the demodulated 2nd positioning assistance information 240 in the memory | storage part 200 (step B27).

  After that, the coordinate transformation matrix generation unit 120 uses the earth orientation parameter (EOP) 243 included in the second positioning support information 240 stored in the storage unit 200 to use the earth center inertia (ECI) coordinate system and the earth center earth. A coordinate transformation matrix Q with a fixed (ECEF) coordinate system is generated (step B29).

  Next, the second ephemeris calculation unit 140 performs a second ephemeris calculation process for each GPS satellite 3 (step B31). Specifically, the satellite position r0 and the satellite velocity v0 of the corresponding GPS satellite 3 included in the second positioning support information 240 are coordinate-transformed using the coordinate transformation matrix Q. Then, a motion equation for the GPS satellite 3 is generated, and numerical integration using the satellite position r0 and satellite velocity v0 after coordinate conversion as initial values is performed on the motion equation, thereby predicting the GPS satellite 3. Predict satellite orbit. Then, the second ephemeris 253 is calculated by obtaining the ephemeris parameters based on the predicted satellite orbit.

  Next, the processing unit 100 updates and stores the second ephemeris 253 stored in the individual satellite information 250 of the storage unit 200 for each GPS satellite 3 (step B33). And the process part 100 complete | finishes a positioning assistance information acquisition process, after performing a flag setting process similarly to step B17 (step B35).

  If it is determined in step B21 that reception of the IMES signal has failed (step B21; No), the processing unit 100 performs flag setting processing in the same manner as in step B17 (step B37). Then, the processing unit 100 ends the positioning support information acquisition process.

  Returning to the position calculation process of FIG. 4, if the positioning support information acquisition process is performed, the processing unit 100 determines whether or not a flag is set (step A3). If it is determined that it is set (step A3; Yes), the position calculation unit 150 performs GPS position calculation processing using the ephemeris according to the setting (step A5).

  Specifically, when the flag is set to “first”, the first ephemeris 252 stored in the storage unit 200 is selected, and when the flag is set to “second”, the memory is stored. The second ephemeris 253 stored in the unit 200 is selected. In this case, the GPS satellite signal acquisition unit 110 obtains measurement information 255 by performing a correlation operation between the received signal and the replica code. Then, using the selected ephemeris and measurement information 255, a known position calculation based on the pseudo distance is performed. The processing unit 100 stores the calculated position and clock error in the storage unit 200 as calculation result data 260.

  On the other hand, if it is determined in step A3 that the flag is not set (step A3; No), the position calculation unit 150 performs normal GPS position calculation processing (step A7). Specifically, the GPS satellite signal acquisition unit 110 acquires the GPS satellite signal from the reception signal, and acquires the reception ephemeris 254 by demodulating the navigation message. Then, using the reception ephemeris 254 and the measurement information 255, a known position calculation based on the pseudorange is performed. Then, the processing unit 100 stores the calculated position and clock error in the storage unit 200 as calculation result data 260.

  In the positioning support information acquisition process, neither the first positioning support information 230 nor the second positioning support information 240 is received, and the first ephemeris 252 and the second ephemeris 253 are stored in the storage unit 200. The situation where neither is memorized is also considered. Of course, since the ephemeris is not held in this case, the ephemeris (reception ephemeris 254) superimposed on the GPS satellite signal is acquired from the GPS satellite signal, and the position is calculated using this. Become. This corresponds to acquiring orbit information superimposed on the satellite signal from the satellite signal when reception of the second positioning support information fails.

  If the processing of step A5 or A7 is performed, the processing unit 100 outputs the calculation result stored in the calculation result data 260 to the host processing unit 30 (step A9). Then, the processing unit 100 ends the position calculation process.

5. Operational Effect The position calculation device 1 tries to receive the first positioning support information from the IMES transmitter 5 that transmits the first positioning support information that is the basis of the calculation of the orbit information of the GPS satellite 3, and the first positioning support When the information is successfully received, the first ephemeris is calculated using the first positioning support information. On the other hand, if the reception of the first positioning support information fails, the second positioning support information is tried to be received from the quasi-zenith satellite 7 that transmits the second positioning support information with lower accuracy than the first positioning support information. . Then, when the second positioning support information is successfully received, the second ephemeris is calculated using the second positioning support information. Then, one ephemeris is selected from the first ephemeris and the second ephemeris, and the position is calculated using the one ephemeris and the satellite signal from the GPS satellite 3.

  That is, priority is given to receiving the first positioning support information with higher accuracy than the second positioning support information. Therefore, it becomes possible to calculate a more accurate ephemeris. In addition, when the reception of the first positioning support information fails, the reception of the second positioning support information is attempted. When the second positioning support information is successfully received, the ephemeris is calculated from the second positioning support information. As a result, even when the first positioning support information cannot be acquired, the ephemeris can be calculated from the second positioning support information.

  Further, before the position calculation is performed, the first positioning support information is received from the IMES transmitter 5 to calculate the first ephemeris. Then, when the reception of the first positioning support information fails, the second positioning support information is received from the quasi-zenith satellite 7 and the second ephemeris is calculated. The initial position calculation time is shortened by selecting one ephemeris from the first ephemeris and the second ephemeris and performing position calculation using the one ephemeris and a satellite signal from a GPS satellite. can do.

  A signal for carrying the ephemeris over a predetermined carrying time is superimposed on the GPS satellite signal. On the other hand, the IMES transmitter 5 transmits the first positioning support information in a shorter time than the transport time, and the quasi-zenith satellite 7 transmits the second positioning support information in a shorter time than the transport time. . The position calculation device 1 receives the first positioning support information in a shorter time than acquiring the ephemeris from the GPS satellite signal, and the second positioning support information in a shorter time than acquiring the ephemeris from the GPS satellite signal. Receive. As a result, the ephemeris can be calculated (predicted) after promptly receiving the positioning support information and used for position calculation.

  In the present embodiment, the ephemeris used for position calculation is selected with reference to the reference date and time of the first ephemeris and the reference date and time of the second ephemeris. Specifically, when the reference date and time of the first ephemeris is newer than the reference date and time of the second ephemeris, the first ephemeris is selected as the ephemeris used for position calculation. The speed information of the GPS satellite 3 included in the first positioning support information is information having a larger number of significant digits than the speed information of the GPS satellite 3 included in the second positioning support information. Accordingly, by calculating the first ephemeris using the first positioning support information, it is possible to obtain orbit information with higher accuracy than in the case of calculating the second ephemeris using the second positioning support information. Can do. As a result, when the position calculation is performed using the first ephemeris, the accuracy of the position calculation is improved as compared with the case where the position calculation is performed using the second ephemeris.

  Even if the reference date and time of the second ephemeris is newer than the reference date and time of the first ephemeris, if the difference between the reference dates and times is within a predetermined time, the first ephemeris is used for position calculation. Select as an ephemeris. This is because it is considered that there is no problem in using the first ephemeris for position calculation if the difference between the reference dates and times is within a predetermined time. Therefore, in order to ensure the accuracy of position calculation, the first priority is given. Of ephemeris. On the other hand, if the difference between the reference dates and times exceeds a predetermined time, the first ephemeris is considered to be out of date, so the second ephemeris that is the new orbital information is used for position calculation. It was decided.

When new first positioning support information is received from the IMES transmitter 5 while the first positioning support information is held, the reference date and time included in the received first positioning support information is held. If it is newer than the reference date and time included in the first positioning support information, the held first positioning support information is updated with the received first positioning support information. Then, a new first ephemeris is calculated and used for position calculation. In this way, it is possible to always use the latest first ephemeris for position calculation.
The same applies to the case where new second positioning support information is received from the quasi-zenith satellite 7 while the second positioning support information is held.

6). Modifications Embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be changed as appropriate without departing from the spirit of the present invention. Hereinafter, modified examples will be described. In addition, about the structure same as the said embodiment, the same code | symbol is attached | subjected and description for the second time is abbreviate | omitted.

6-1. Transmission Source In the above embodiment, the first transmission source has been described as the IMES transmitter 5 which is a kind of ground communication device. However, the first transmission source is not limited to the IMES transmitter 5 and may be a server device having a transmission function inside or outside, a ground communication device such as a mobile phone or a data communication base station. In that case, it is preferable that the ground communication apparatus is configured to transmit by the same transmission method (transmission protocol, transmission frequency, modulation method, etc.) as the above-mentioned artificial satellite. When transmitting by a different transmission method, the position calculation device 1 needs to have a reception function corresponding to the transmission method.

  In the above-described embodiment, the second transmission source is described as the quasi-zenith satellite 7 which is a kind of artificial satellite, but may be a stationary satellite instead of the quasi-zenith satellite 7. A geostationary satellite is suitable when the area where the position calculation device 1 is used is an area near the equator.

6-2. Positioning support information In the above-described embodiment, the first positioning support information has been described as including speed information of the GPS satellite 3 with higher accuracy than the second positioning support information. However, instead of this, the first positioning support information may include the position information of the GPS satellite 3 with higher accuracy than the second positioning support information. This can be realized by making the effective number of position information included in the first positioning support information larger than the effective number of position information included in the second positioning support information.

  It should be noted that the first positioning support information has a larger number of significant digits than the second positioning support information for both of the information, not the position information or the speed information of the GPS satellite 3. Of course, it is also good.

6-3. Selection of Ephemeris The selection method of the ephemeris used for position calculation is not limited to the selection method described in the above embodiment. For example, high-precision first positioning support information could be received from the IMES transmitter 5 in a state where the low-precision second positioning support information received from the quasi-zenith satellite 7 is stored in the storage unit 200. In this case, regardless of the reference date and time, the first ephemeris calculated using the received first positioning support information may be selected as the ephemeris used for position calculation.

  In addition, it is possible to receive the low-precision second positioning support information from the quasi-zenith satellite 7 in a state where the high-precision first positioning support information received from the IMES transmitter 5 is stored in the storage unit 200. In addition, when a long period of time has elapsed since the reference date and time included in the first positioning support information, the second ephemeris calculated using the received second positioning support information is used as an ephemeris used for position calculation. It is good also as selecting.

6-4. Position Calculation of GPS Satellite In the above embodiment, the position calculation device 1 obtains the satellite orbit (orbit function r (t)) of the GPS satellite 3 from the positioning support information, and calculates (predicts) the ephemeris representing this satellite orbit. It was to be. However, the position calculation apparatus 1 may directly obtain the position of the GPS satellite 3 from the satellite orbit (orbit function r (t)) and perform position calculation using this satellite position. That is, after calculating the predicted satellite orbit (that is, the orbit function r (t) representing the satellite orbit) for each GPS satellite 3, the position of the GPS satellite 3 at the positioning time t is calculated from the predicted orbit. It may be used for position calculation.

  Then, using the satellite position calculated in this way, for example, a known position calculation using a pseudorange may be performed to calculate the position. According to this, it is possible to obtain an effect that it is not necessary to calculate the ephemeris from the predicted trajectory or to acquire the ephemeris by continuously receiving the GPS satellite signal.

6-5. Satellite Positioning System In the above-described embodiment, the position calculation device 1 that acquires the ephemeris of the GPS satellite 3 and calculates the position has been described as an example. That is, the satellite positioning system has been described as GPS. However, the method of the present invention can be applied substantially to satellite positioning systems such as WAAS (Wide Area Augmentation System), GLONASS (GLObal NAvigation Satellite System), GALILEO, and Beidou.

6-6. Generation of the first positioning support information and the second positioning support information In the above embodiment, the first positioning support information and the second positioning support information are generated using the ephemeris acquired from the GPS satellite 3. The case has been described as an example. However, the method for generating the first positioning support information and the second positioning support information is not limited to this, and the first positioning support information and the second positioning support information are generated using information other than the ephemeris. May be.

  1 position calculation device, 3 GPS satellite, 5 IMES transmitter, 7 quasi-zenith satellite, 10 antenna, 20 reception unit, 21 RF reception circuit unit, 22 baseband processing circuit unit, 30 host processing unit, 31 operation unit, 32 display Unit, 33 sound output unit, 34 clock unit, 35 storage unit, 100 processing unit, 200 storage unit

Claims (6)

Attempting to receive the first positioning support information from a first transmission source that transmits the first positioning support information that is the basis for calculating the orbit information of the positioning satellite;
Calculating the first trajectory information using the first positioning support information when the first positioning support information is successfully received;
Reception of the second positioning support information from a second transmission source that transmits second positioning support information with lower accuracy than the first positioning support information when reception of the first positioning support information fails. And trying
Calculating the second trajectory information using the second positioning support information when the second positioning support information is successfully received;
Of the first trajectory information and the second trajectory information, the trajectory information used for position calculation is calculated using the difference between the reference date and time of the first trajectory information and the reference date and time of the second trajectory information. Selecting and calculating the position using the selected orbit information and the satellite signal from the positioning satellite;
A method for controlling a position calculation device including: The satellite signal is superimposed with a signal carrying the orbit information over a predetermined carrying time,
The first transmission source transmits the first positioning support information in a shorter time than the transport time,
The second transmission source transmits the second positioning support information in a shorter time than the transport time,
The first positioning support information is received in a shorter time than acquiring the orbit information from the satellite signal,
The second positioning support information is received in a shorter time than acquiring the orbit information from the satellite signal.
The control method according to claim 1. The first positioning support information is information having a larger effective digit number than the second positioning support information.
The control method according to claim 1 or 2. Acquiring orbit information superimposed on the satellite signal from the satellite signal when reception of the second positioning support information fails;
The control method according to any one of claims 1 to 3, further comprising: The first and second positioning support information includes information on the position and speed of the positioning satellite,
The calculation of the first orbit information uses the equation of motion representing the motion of a satellite orbiting the earth and the position and velocity of the positioning satellite included in the first positioning support information. Calculating the trajectory information of one,
The calculation of the second orbit information is to calculate the second orbit information using the equation of motion and the position and velocity of the positioning satellite included in the second positioning support information. including,
The control method as described in any one of Claims 1-4 . A signal from the first transmission source that transmits the first positioning support information that is the basis for calculating the orbit information of the positioning satellite and the second positioning support information that is less accurate than the first positioning support information are transmitted. A position calculation device capable of receiving a signal from a second transmission source,
Attempting to receive the first positioning assistance information;
Calculating the first trajectory information using the first positioning support information when the first positioning support information is successfully received;
If reception of the first positioning support information fails, attempting to receive the second positioning support information;
Calculating the second trajectory information using the second positioning support information when the second positioning support information is successfully received;
Of the first trajectory information and the second trajectory information, the trajectory information used for position calculation is calculated using the difference between the reference date and time of the first trajectory information and the reference date and time of the second trajectory information. Selecting and calculating the position using the selected orbit information and the satellite signal from the positioning satellite;
The position calculation device that executes

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