WO2014083745A1

WO2014083745A1 - Control method for position calculating device and position calculating device

Info

Publication number: WO2014083745A1
Application number: PCT/JP2013/006003
Authority: WO
Inventors: 村木　清孝
Original assignee: セイコーエプソン株式会社
Priority date: 2012-11-30
Filing date: 2013-10-08
Publication date: 2014-06-05
Also published as: JP2014109442A

Abstract

The purpose of the present invention is to shorten the time to first fix (TTFF). A position calculating device (1) determines whether orbital information for a GPS satellite (3) stored in memory satisfies prescribed useful conditions. If the determination is negative, positioning assistance information is acquired from an IMES transmitter (5), which is a type of ground communication device that sends the positioning assistance information that is the basis for calculating orbital information. In addition, the orbital information is calculated using the acquired positioning assistance information, the orbital information stored in memory is updated, and the position of the position calculating device (1) is calculated using the signal from the GPS satellite (3) and the orbital information stored in memory.

Description

Method for controlling position calculation apparatus and position calculation apparatus

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

GPS (Global Positioning System) is widely known as a position calculation system using positioning signals from positioning satellites. 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.

In recent years, portable electronic devices such as portable telephones, PDAs, portable navigation devices, and wristwatches have been equipped with position calculation devices that are not only used outdoors like car navigation devices, but also in buildings. It is also used in various places such as underground and underground. However, there is a problem that the position calculation device cannot receive the GPS satellite signal at all in the building or underground, or it is difficult to receive the GPS satellite signal, and the position calculation cannot be performed.

Therefore, for example, Patent Document 1 discloses a position information providing system using an indoor transmitter as a technique for providing position information to a position calculation device in a place where a GPS satellite signal does not reach.

JP 2009-85928 A

Certainly, according to the technique disclosed in Patent Document 1, even when the position calculation device exists indoors, the position calculation device specifies the position of the own device based on the position information transmitted from the indoor transmitter. be able to. However, the problem here is the case where the position calculation is performed after the position calculation device goes out of the room.

For example, in a facility such as a shopping mall or underground mall, a user carrying a position calculation device may stay indoors for many hours. However, of the orbit information broadcast from the GPS satellite, the effective period of the ephemeris is a maximum of 4 hours in the current satellite operation. For this reason, even if the position calculation device receives the GPS satellite signal and acquires the orbit information before entering the room, the orbit information cannot be used for position calculation when the user stays indoors for a long time. There is a case.

In this case, since the expiration date of the trajectory information has passed, when the position calculation is started by moving from indoors to the outdoors, it becomes a so-called warm start state (note that even the almanac is not held or has expired) A cold start in some cases). In this state, the position calculation device cannot perform position calculation unless it acquires an ephemeris from a GPS satellite after going outdoors. However, demodulation of the ephemeris requires a time of at least about 30 seconds per satellite, which inevitably increases the initial position calculation time (TTFF: Time To First Fix).

The present invention has been made in view of the above problems, and its object is to shorten the initial position calculation time (TTFF).

A first invention for solving the above problem is a control method of a position calculation device, wherein it is determined whether orbit information of a positioning satellite stored in a storage unit satisfies a predetermined useful condition. And, when the result of the determination is a negative determination, executing a first acquisition process of acquiring the positioning support information from the ground communication device that transmits the positioning support information that is the basis of the calculation of the trajectory information; The orbit information is calculated using the obtained positioning support information, the orbit information stored in the storage unit is updated, the signal from the positioning satellite, and the orbit stored in the storage unit. Calculating the position of the position calculating device using information.

As another invention, a storage unit that stores orbit information of a positioning satellite, a determination unit that determines whether orbit information stored in the storage unit satisfies a predetermined useful condition, and When the determination result is negative, the acquisition unit that acquires the positioning support information from the ground communication device that transmits the positioning support information that is the basis of the calculation of the orbit information, and the acquired positioning support information Using the calculation unit that calculates the orbit information and updates the orbit information stored in the storage unit, the signal from the positioning satellite, and the orbit information stored in the storage unit, the position calculation device A position calculation apparatus including a position calculation unit that calculates a position may be configured.

According to the first aspect of the invention, when the orbit information of the positioning satellite stored in the storage unit does not satisfy the predetermined useful condition, the positioning support information is acquired from the ground communication device, and the orbit information is used by using this information. Is calculated and the trajectory information in the storage unit is updated. This makes it possible to store useful orbit information in the storage unit before performing position calculation using signals from positioning satellites. Then, the initial position calculation time can be shortened by calculating the position of the position calculation device using the signal from the positioning satellite and the orbit information stored in the storage unit.

As a second invention, in the control method of the first invention, the orbit information includes 1) first orbit information calculated from the positioning support information, and 2) a signal from the positioning satellite. A control method including at least one of the second orbit information obtained by demodulation may be configured.

According to the second aspect of the invention, the orbit information includes 1) first orbit information calculated from positioning support information, and 2) second orbit information obtained by demodulating a signal from a positioning satellite. And at least one of. Thereby, among the orbit information of the positioning satellite stored in the storage unit, the first orbit information calculated from the positioning support information and the second orbit information obtained by demodulating the signal from the positioning satellite. If it is determined that is not useful, positioning support information can be acquired from the ground communication device.

As a third invention, in the control method of the first or second invention, when the first acquisition process fails, the orbit information is acquired by demodulating a signal from the positioning satellite. It is good also as comprising the control method which further includes performing a 2nd acquisition process.

According to the third invention, when the first acquisition process for acquiring the positioning support information from the ground communication device fails, the second acquisition for acquiring the orbit information by demodulating the signal from the positioning satellite. Execute the process. In other words, the first acquisition process is executed with priority over the second acquisition process. If the first acquisition process executed with priority fails, the second acquisition process is executed because there is a possibility of being outdoors.

According to a fourth aspect of the present invention, in the control method of the third aspect, the ground communication device uses the spread code different from that of the positioning satellite, and uses the same spread spectrum method as the positioning satellite to support the positioning. An information transmitting device, wherein the obtaining includes receiving a signal from the ground communication device in the first obtaining process and receiving a signal from the positioning satellite in the second obtaining process. It is also possible to constitute a control method including realizing by switching the spreading code.

According to the fourth aspect of the invention, the terrestrial communication device is a device that transmits positioning support information using the same spread spectrum method as that of the positioning satellite using a spreading code different from that of the positioning satellite. Therefore, by switching the spreading code, it is possible to realize reception of a signal from the ground communication device in the first acquisition process and reception of a signal from the positioning satellite in the second acquisition process. For the position calculation device, it is possible to receive signals from the ground communication device and signals from the positioning satellite with a common receiving unit.

Further, as a fifth invention, in the control method of any one of the first to fourth inventions, the positioning support information includes position and speed information and time information of the positioning satellite, To calculate the orbit information, using the equation of motion representing the movement of the satellite orbiting the earth, the position and velocity information of the positioning satellite included in the positioning support information and the time information, It is good also as comprising the control method which is calculating.

According to the fifth aspect of the invention, the positioning support information includes the position and speed information of the positioning satellite and the time information. The equation of motion representing the motion of the satellite orbiting the earth, and the positioning support information. Orbital information of the positioning satellite can be calculated by using the position and velocity information and time information of the positioning satellite included in.

Further, as a sixth invention, in the control method of any one of the first to fifth inventions, the storage unit stores an effective period of the orbit information in association with the orbit information, and the determination Doing may constitute a control method including determining whether or not the useful condition is satisfied based on the effective period.

According to the sixth aspect of the invention, the effective period of the orbit information is stored in the storage unit in association with the orbit information. Therefore, the usefulness of the trajectory information can be easily determined based on the effective period.

Further, as a seventh invention, in the control method of the sixth invention, the storage unit stores a reliability index value of the orbit information in association with the orbit information and stores the determination. This may constitute a control method including determining whether or not the useful condition is satisfied based on a combination of the valid period and the reliability index value.

According to the seventh aspect of the invention, the storage unit stores the reliability index value of the orbit information in association with the orbit information. And it is determined whether useful conditions are satisfy | filled based on the combination of an effective period and a reliability parameter | index value. Even if the validity period of the orbit information has not expired, if the reliability of the orbit information is low, the orbit information cannot be said to be useful information. For this reason, based on the combination of the effective period and the reliability index value, it is possible to more accurately determine the usefulness of the 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 position calculation apparatus. The figure which shows an example of a function structure of a baseband process circuit part. The flowchart which shows the flow of a baseband process. The figure which shows the modification of a position calculation system.

Hereinafter, an example of a preferred embodiment to which the present invention is applied will be described with reference to the drawings. In this embodiment, a 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 1000 according to the present embodiment.
The position calculation system 1000 includes a position calculation device 1, a GPS satellite 3, an IMES (Indoor Messaging System) transmitter 5, a GNSS (Global Navigation Satellite System) base station 6, an outdoor GPS receiver 7, and a precise calendar. And a server 8. The IMES transmitter 5, the GNSS base station 6, the outdoor GPS receiver 7, and the fine calendar providing server 8 are connected to each other via a network N.

The network (distribution network, communication line) N is a communication path using, for example, the Internet or a wireless LAN (Local Area Network), and is a LAN using a dedicated line (dedicated cable) or Ethernet (registered trademark) for direct connection. In addition, a communication network such as a telephone communication network, a cable network, and a wireless LAN can be included. The communication method may be wired / wireless.

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 kind of ground communication device, and is arranged in various places in the room, and transmits positioning support information that is information for supporting GPS positioning. In the example of FIG. 1, it is installed on each floor of the building. As the facility where the IMES transmitter 5 is arranged, for example, various indoor facilities such as a shopping mall, an underground mall, an airport, a movie theater, and a hotel are conceivable. A PRN code different from that of the GPS satellite 3 is assigned to the IMES transmitter 5, and positioning support information is transmitted by the same spread spectrum method as that of the GPS satellite 3 using the assigned PRN code.

In this embodiment, the IMES transmitter 5 acquires the ephemeris of the GPS satellite 3 distributed from the GNSS base station 6 via the network N (hereinafter referred to as “distributed ephemeris”). Then, positioning support information generation processing for generating positioning support information for all GPS satellites 3 is performed using the acquired distribution ephemeris, and the positioning support information is included in the IMES signal compliant with the GPS satellite signal standard (communication standard). To send.

The positioning support information transmitted from the IMES transmitter 5 is information serving as a basis for calculating the orbit information of the GPS satellite 3, and in this embodiment, the satellite position speed information of each GPS satellite 3 and the earth attitude parameter (Earth Orientation Parameter: EOP).

The satellite position speed information includes the satellite position r0 and the satellite speed v0 at a certain reference time t0 of each GPS satellite 3 and a clock error. The Earth attitude parameters, which are the Earth attitude information, are UT1-UTC, day length (Length Of Day: LOD), X-pole motion, X-pole motion speed, Y-pole motion, and Y-pole motion speed. Contains.

When the IMES transmitter 5 acquires the distribution ephemeris from the GNSS base station 6, the IMES transmitter 5 performs positioning support information generation processing. First, a reference time t0 is set. The reference time t0 may be, for example, the time when the distribution ephemeris is acquired, or may be the start time of the effective period of the distribution ephemeris. Then, the satellite position r0 and the satellite velocity v0 at the reference time t0 are calculated using the values of the satellite orbit parameters included in the distribution ephemeris, and these information, clock error information, and earth attitude parameter EOP information are collected. Thus, positioning support information is generated.

The GNSS base station 6 is installed, for example, in various parts of the world, receives satellite signals from a plurality of types of GNSS satellites including the GPS satellite 3, and acquires and distributes data necessary for positioning. In the present embodiment, the GNSS base station 6 periodically receives a GPS satellite signal from the GPS satellite 3, and acquires a broadcast ephemeris (broadcast calendar) from the received GPS satellite signal. Then, the acquired broadcast ephemeris is distributed as a distribution ephemeris to the IMES transmitter 5 via the network N.

The outdoor GPS receiver 7 is, for example, a GPS receiver disposed on the roof of a building where the IMES transmitter 5 is installed, and a predetermined vicinity condition (for example, within 1 km) from the position of the IMES transmitter 5 in the ground plane coordinates. The GPS satellites 3 are installed at positions where the sky arrangement of the GPS satellites 3 can be said to be substantially the same, such as a position that satisfies The outdoor GPS receiver 7 then acquires a navigation message by demodulating the GPS satellite signal received from the GPS satellite 3. Then, the ephemeris obtained from the acquired navigation message is transmitted to the IMES transmitter 5 via the network N.

The precision calendar providing server 8 is a server that provides a precision calendar that is a high-precision GPS calendar. The precision calendar providing server 8 is a server or server system installed in an organization or organization established for the purpose of, for example, observing the GPS satellite 3 or analyzing the data and distributing the observation data of the high-precision GPS satellite. is there. In the present specification, the precision calendar providing server 8 will be described as transmitting a breaking calendar or a super breaking calendar, which is a kind of the precision calendar, to the IMES transmitter 5 via the network N.

In this embodiment, the IMES transmitter 5 acquires broadcast ephemeris related to all GPS satellites 3 from the GNSS base station 6, and uses this to generate and transmit positioning support information for all GPS satellites 3. . In this case, the position calculation device 1 acquires the positioning support information of all the GPS satellites 3 from the IMES transmitter 5 indoors. And the ephemeris of all the GPS satellites 3 is calculated using this, and the ephemeris memorize | stored in the memory | storage part is updated. When the signal from the GPS satellite 3 can be received, the position of the own device is calculated using the signal from the GPS satellite 3 and the ephemeris stored in the storage unit.

2. Principle of Ephemeris Calculation (Estimation) The principle of the position calculation device 1 calculating (estimating) the ephemeris of the GPS satellite 3 based on the positioning support information acquired from the IMES transmitter 5 will be described. The positioning support information includes satellite position speed information (position and speed information) of each GPS satellite 3 and an earth attitude parameter (EOP).

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 equation (2), a _g is gravitational acceleration, a _moon is lunar attraction, a _sun is solar attraction, and 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.

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 time t0, which are included in the 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 transmitted by the IMES transmitter 5 are based on the earth center, which is a coordinate system fixed to the earth. Defined in the Earth Centered Earth Fixed (ECEF) coordinate system.

For this reason, when estimating the satellite orbit, coordinate conversion between the Earth Center Inertia (ECI) coordinate system and the Earth Center Earth Fixed (ECEF) coordinate system is required. 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. 2 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 satellite signal 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. Configured.

The antenna 10 is an antenna that receives a GPS satellite signal transmitted from the GPS satellite 3 and an RF (Radio Frequency) signal including the IMES signal transmitted from the IMES transmitter 5.

The satellite signal receiving unit 20 includes an RF receiving circuit unit 21 and a baseband processing circuit unit 22. For example, the satellite signal receiving unit 20 demodulates the positioning support information from the IMES signal received by the antenna 10, or is received by the antenna 10. Performs processing such as demodulating navigation messages from GPS satellite signals. Further, the ephemeris is calculated using the positioning support information, and the position of the position calculation device 1 is calculated by performing a known position calculation using a pseudorange based on the satellite position obtained from the ephemeris. The RF receiving circuit unit 21 and the baseband processing circuit unit 22 can be manufactured as separate LSIs (Large Scale Integration) or as a single 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 used. The digital signal may be output to the baseband processing circuit unit 22 by subjecting the signal to analog signal processing and finally 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 performs carrier removal, correlation processing, and the like on the signal received by the RF receiving circuit unit 21 to capture a GPS satellite signal and an IMES signal. In the present embodiment, the baseband processing circuit unit 22 determines whether or not the ephemeris 232 of the GPS satellite 3 stored in the storage unit 200 satisfies a predetermined useful condition. If the determination result is negative, the positioning support information 220 is acquired from the IMES transmitter 5, the ephemeris is calculated using the positioning support information 220, and the ephemeris 232 stored in the storage unit 200 is updated. To do. Then, using the signal from the GPS satellite 3 and the ephemeris 232 stored in the storage unit 200, the position (position coordinates) and clock error (clock bias) of the position calculation device 1 are calculated.

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 and includes an oscillation circuit such as a crystal oscillator.

The storage unit 35 is implemented 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. 3 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 also functions as a GPS satellite signal acquisition unit 110, an IMES signal acquisition unit 120, a useful condition determination unit 130, a coordinate transformation matrix generation unit 140, an ephemeris calculation unit 150, and a position calculation unit 160. Have as 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 capturing unit 110 captures GPS satellite signals. 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 reception 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 ephemeris acquired in advance in an outdoor environment or the like is stored in the storage unit 200 as the ephemeris 232 of the GPS satellite 3.

The IMES signal capturing unit 120 captures the IMES signal. That is, similar to the acquisition of the GPS satellite 3 by the GPS satellite signal acquisition unit 110, the PRN code replica code assigned to the IMES transmitter 5 is used for the reception signal output from the RF reception circuit unit 21. The IMES signal is captured by performing a correlation operation. Then, the positioning support information 220 is demodulated and acquired from the captured IMES signal and stored in the storage unit 200.

The useful condition determination unit 130 determines whether or not the ephemeris (orbit information) 232 stored in the storage unit 200 satisfies a predetermined useful condition. In the present embodiment, the useful condition determination unit 130 determines whether the useful condition is satisfied based on the validity period of the ephemeris 232.

The coordinate transformation matrix generation unit 140 uses the earth attitude parameter (EOP) 222 included in the positioning support information 220, the earth center inertia (ECI) coordinate system defined as the above-described equation (4), and the earth center A coordinate transformation matrix Q with respect to the earth fixed (ECEF) coordinate system is calculated.

The ephemeris calculation unit 150 calculates the ephemeris 232 of each GPS satellite 3 based on the positioning support information 220 acquired from the IMES transmitter 5. Specifically, using the coordinate transformation matrix Q generated by the coordinate transformation matrix generation unit 140, the satellite position r0 and the satellite velocity v0 of the GPS satellite 3 included in the positioning support information 220 are fixed to the center of the 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 232 that matches the satellite orbit represented by the orbit function r (t) is calculated. The ephemeris 232 is calculated by, for example, a numerical calculation (for example, the least square method) that minimizes the difference between the satellite orbit based on the specified ephemeris parameter value and the satellite orbit represented by the orbit function r (t). Can do. However, it goes without saying that other methods may be used.

The position calculation unit 160 calculates the position of the position calculation device 1. Specifically, using the ephemeris 232 and measurement information 233 of each captured satellite stored in the storage unit 200, for example, a known position calculation using a least square method or a Kalman filter is performed, and the position of the position calculation device 1 is detected. And the clock error is calculated.

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, a baseband processing program 210, positioning support information 220, individual satellite information 230, and calculation result data 240 are stored.

The baseband processing program 210 is a program that is read by the processing unit 100 and executed as baseband processing (see FIG. 4).

The positioning support information 220 includes satellite-specific information 221 and an earth attitude parameter (EOP) 222. The satellite-specific information 221 is individual information for each GPS satellite 3, and includes satellite number 221A, reference time information 221B, satellite position information 221C, satellite speed information 221D, and satellite clock error information 221E. It is.

The individual satellite information 230 is individual information of each GPS satellite 3 and is information generated for each GPS satellite 3. Specifically, a satellite number 231, an ephemeris 232, and measurement information 233 are included.

In the ephemeris 232, in addition to the satellite orbit parameters, an epoch time toe that determines the valid period of the ephemeris 232 is stored. This corresponds to the storage unit 200 storing the valid period of the orbit information in association with the orbit information.
The measurement information 233 includes various amounts (for example, code phase and Doppler frequency) related to the received GPS satellite signal acquired by performing so-called phase search and frequency search.

The calculation result data 240 is data in which a calculation result calculated by the position calculation unit 160 performing a position calculation process is stored, and includes a calculated position and a clock error.

4). Processing Flow FIG. 4 is a flowchart illustrating the flow of baseband processing executed by the processing unit 100 according to the baseband processing program 210 stored in the storage unit 200. This baseband 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 determines a GPS satellite 3 that can be used for position calculation (hereinafter referred to as “positioning usable satellite”). Specifically, for example, when an almanac or long-term predicted ephemeris is already stored in the storage unit 200, a GPS satellite positioned in the sky at a given reference position at the current date and time counted by the clock unit 34 3 is determined using these data, and this is used as a positioning usable satellite. The reference position can be, for example, a calculated position obtained by positioning last time.

Next, the useful condition determination unit 130 determines whether or not the ephemeris 232 stored in the storage unit 200 satisfies a predetermined useful condition for each positioning usable satellite (step A3). Specifically, the remaining time until the valid period expires is determined based on the time information toe included in the ephemeris 232 of each positioning usable satellite and the current time. If the valid period has already elapsed or the remaining time is within a predetermined threshold time (for example, within 30 minutes), it is determined that the ephemeris 232 is not useful.

Next, the processing unit 100 determines whether or not the ephemeris 232 that satisfies the useful condition of the positioning usable satellite is stored in the storage unit 200 based on the determination result of Step A3 (Step A5). Specifically, it is determined whether or not the ephemeris 232 stored in the storage unit 200 satisfies the above-described useful conditions for all positioning usable satellites.

If the determination result in step A5 is negative (step A5; No), the IMES signal acquisition unit 120 searches for the IMES signal (step A7). Specifically, using the replica code of the PRN number assigned to the IMES transmitter 5, the correlation calculation with the signal received by the RF receiving circuit unit 21 is performed to determine whether or not the correlation is obtained.

Next, it is determined whether or not the IMES signal has been acquired by searching for the IMES signal (step A9). If it is determined that the IMES signal has been captured (step A9; Yes), the processing unit 100 demodulates the positioning support information 220 from the captured IMES signal and stores it in the storage unit 200 (step A11).

In this embodiment, since the positioning support information 220 of all GPS satellites 3 is transmitted from the IMES transmitter 5, the positioning support information 220 of all GPS satellites 3 is demodulated and stored in the storage unit 200. Further, the process of acquiring the IMES signal and acquiring the positioning support information corresponds to the first acquisition process of acquiring the positioning support information from the ground communication device.

Thereafter, the coordinate transformation matrix generation unit 140 uses the earth attitude parameter (EOP) 222 included in the positioning support information 220 acquired in step A11, and uses the earth center inertia (ECI) coordinate system and the earth center earth fixed (ECEF) coordinates. A coordinate transformation matrix Q with the system is generated (step A13).

Next, the ephemeris calculation unit 150 performs an ephemeris calculation process for each GPS satellite 3 (steps A15 to A23). In the ephemeris calculation process, first, the satellite position r0 and the satellite velocity v0 of the corresponding GPS satellite 3 included in the acquired positioning support information 220 are coordinate-converted using the coordinate conversion matrix Q (step A15).

Next, a motion equation for the GPS satellite 3 is generated (step A17), and numerical integration is performed on the motion equation using the satellite position r0 and the satellite velocity v0 after coordinate conversion as initial values. 3 predicted satellite orbits (step A19).

Then, the ephemeris is calculated by obtaining the ephemeris parameters based on the predicted satellite orbit (step A21), and the ephemeris 232 stored in the storage unit 200 is updated (step A23). After performing the ephemeris calculation process for each GPS satellite 3, the processing unit 100 returns to Step A1.

On the other hand, if the determination result of step A5 is affirmative (step A5; Yes), the GPS satellite signal acquisition unit 110 searches for a GPS satellite signal of a positioning usable satellite (step A25). Specifically, a correlation calculation with the signal received by the RF receiving circuit unit 21 is performed using the replica code of the PRN number assigned to the positioning usable satellite, and it is determined whether or not the correlation is obtained.

As described above, in the IMES signal search (step A7) and the GPS satellite signal search (step A25), the PRN code assigned to the IMES transmitter 5 and the PRN code assigned to the GPS satellite 3 are switched. In this way, two types of signals are captured. This corresponds to realizing the reception of the signal from the ground communication device in the first acquisition process and the reception of the signal from the positioning satellite in the second acquisition process by switching the spreading code.

If the GPS satellite signal cannot be acquired by searching for the GPS satellite signal (step A27; No), the processing unit 100 determines that the position calculation has failed and ends the baseband processing.

On the other hand, when the GPS satellite signal can be acquired (step A27; Yes), the GPS satellite signal acquisition unit 110 starts a demodulation process for demodulating the navigation message from the GPS satellite signal received from the positioning usable satellite (step A29). ).

Next, the position calculation unit 160 starts the GPS position calculation process (step A31). Specifically, using the ephemeris 232 stored in the storage unit 200 and the measurement information 233 acquired by capturing the GPS satellite signal, the position of the position calculating device 1 A clock error is calculated and stored in the storage unit 200 as calculation result data 240.

In this case, the useful ephemeris of the positioning usable satellite is already stored in the storage unit 200 (step A5; Yes). Therefore, the position calculation can be completed promptly without waiting for demodulation of the ephemeris contained in the signal from the positioning usable satellite. Thereby, shortening of initial position calculation time (TTFF) is realizable. Thereafter, the navigation message demodulation process and the position calculation process are continuously executed until the position calculation end operation is performed. When the end operation is performed (step A33; Yes), the baseband process is ended.

If it is determined in step A9 that the IMES signal could not be captured (step A9; No), the processing unit 100 captures a GPS satellite signal from the positioning use satellite (step A35). The fact that the IMES signal cannot be captured means that the position calculation device 1 is likely to be located outdoors, and therefore searches for and captures GPS satellite signals from positioning-enabled satellites.
Then, the processing unit 100 proceeds to Step A29.

In this case (Step A5; No → Step A9; No), the useful ephemeris of the positioning usable satellite is not stored in the storage unit 200. For this reason, position calculation cannot be performed until demodulation of the ephemeris included in the signal from the positioning enabled satellite is completed. Therefore, it takes a certain amount of time to complete the position calculation.

Step A9; No → Step A35 → Step A29 is the flow of acquiring orbit information by demodulating the signal from the positioning satellite when the first acquisition process for acquiring the positioning support information from the ground communication device fails. This corresponds to executing the second acquisition process.

5. Effects According to the present embodiment, in the position calculation device 1, the useful condition determination unit 130 determines whether or not the ephemeris of the GPS satellite 3 stored in the storage unit 200 satisfies a predetermined useful condition. When the determination result of the useful condition determination unit 130 is negative, the IMES signal acquisition unit 120 obtains the positioning support information from the IMES transmitter 5 that transmits the positioning support information that is the basis of the ephemeris calculation. Execute the acquisition process. Then, the ephemeris calculation unit 150 calculates the ephemeris parameters using the acquired positioning support information, and updates the ephemeris in the storage unit 200. Then, the position calculation unit 160 calculates a position using the signal from the GPS satellite 3 and the ephemeris stored in the storage unit 200.

This makes it possible to calculate a useful ephemeris and store it in the storage unit 200 before calculating the position using the signal from the GPS satellite 3. Then, by calculating the position of the position calculation device 1 using the signal from the GPS satellite 3 and the ephemeris stored in the storage unit 200, when the position calculation device 1 moves from the indoor to the outdoor, Position calculation can be started (so-called hot start), and the initial position calculation time (TTFF) can be shortened.

In this embodiment, positioning support information for all GPS satellites is transmitted from the IMES transmitter 5. Therefore, the position calculation device 1 can acquire not only the current visible satellite positioning support information but also the GPS satellite positioning support information that will become a visible satellite in the future from the IMES transmitter 5. In other words, the ephemeris can be calculated (estimated) indoors in advance and stored in the storage unit for the GPS satellite 3 that can be a visible satellite in the future. As a result, even when the visible satellite changes with time, position calculation can be started promptly.

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. Terrestrial communication apparatus In the above embodiment, the terrestrial communication apparatus has been described as the IMES transmitter 5, but instead of the IMES transmitter 5, a server apparatus having a transmission function inside or outside, a mobile phone, or a data communication device A ground communication device such as a base station may be used. 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 GPS satellite signal. When transmitting by a different transmission method, the position calculation device 1 needs to have a reception function corresponding to the transmission method.

6-2. Determination of useful condition of trajectory information In the above embodiment, it is determined whether or not the ephemeris satisfies the useful condition based on the effective period of the ephemeris stored in the storage unit 200 of the position calculation device 1. The judgment criteria for judging whether are not limited to the valid period.

For example, an ephemeris broadcast from a GPS satellite stores a parameter value called a URA (User Range Accuracy) index (hereinafter simply referred to as “URA”) as an index value indicating the reliability of orbit information. Yes. This URA is represented by a numerical value from “0 to 15”, and the smaller the value, the higher the reliability of the ephemeris as the trajectory information, which is suitable for position calculation. Therefore, it may be determined whether or not the ephemeris satisfies a useful condition by using the URA as a reliability index value of the orbit information and performing a threshold determination on the URA. Specifically, for example, it may be determined as a useful condition that URA is equal to or less than a predetermined threshold (for example, 4).

In this case, it is more effective to determine whether or not the useful condition is satisfied based on the combination of the validity period of the ephemeris described in the above embodiment and the reliability index value. This is because even if the ephemeris is within the effective period, if the position calculation is performed using the ephemeris with low reliability, the accuracy of the position calculation is lowered. Therefore, for example, it may be determined as a useful condition that the remaining time until the expiration date is longer than a predetermined threshold time (for example, 30 minutes) and the URA value is not more than a predetermined threshold (for example, 4). Good.

Also, the ephemeris stored in the storage unit 200 by the position calculation device 1 is not limited to broadcast ephemeris information broadcast from the GPS satellite 3. A configuration in which a broadcast ephemeris is acquired from a server using a so-called server assist technology is conceivable. Therefore, these ephemeris obtained by server assist may be stored in the storage unit 200, and useful conditions may be determined for these ephemeris. Further, the ephemeris acquired by server assist may be a so-called long-term predicted ephemeris.

Also, after the position calculation device 1 receives the positioning support information from the IMES transmitter 5 and estimates the ephemeris, the valid period of the ephemeris may be expired. Therefore, the useful condition of the ephemeris is determined based on the effective period of the ephemeris calculated using the positioning support information. When the negative determination is made, the ephemeris is calculated by acquiring the positioning support information again from the IMES transmitter 5. It may be fixed.

That is, the ephemeris 232 (orbit information) stored in the storage unit 200 is demodulated by 1) a first ephemeris (first orbit information) calculated from positioning support information and 2) a signal from a GPS satellite. The obtained second ephemeris (second orbit information) is at least one. And what is necessary is just to determine whether the ephemeris which satisfy | fills useful conditions is memorize | stored in the memory | storage part 200 in step A3, A5 of FIG.

6-3. Generation / Transmission of Positioning Support Information In the above embodiment, it has been described that the GNSS base station 6 distributes the broadcast ephemeris to the IMES transmitter 5. However, the GNSS base station 6 generates positioning support information and the IMES transmitter 5. It is good also as a structure delivered to.

Further, the IMES transmitter 5 does not generate and transmit the positioning support information based on the broadcast ephemeris distributed from the GNSS base station 6, but based on the breaking calendar or the super breaking bulletin distributed from the precise calendar providing server 8. The IMES transmitter 5 may generate and transmit positioning support information for all GPS satellites 3.

For example, the precise calendar providing server 8 can be configured to transmit and provide the IMES transmitter 5 with a super-rapid calendar including a determined value of the position of the GPS satellite 3 and a highly accurate forecast value. Since the ultra-rapid calendar contains the predicted value of the position of the GPS satellite 3, it can be used in real time in principle.

Here, the ultra-rapid calendar currently in operation is given as discrete data of the satellite position and the satellite clock error at the sampling time every fixed sampling time interval (for example, every 15 minutes). Therefore, in the positioning support information generation process, the IMES transmitter 5 sets, for example, the latest sample time of the current time as the reference time t0, reads the predicted value of the satellite position at the sample time, and includes it in the positioning support information The satellite position is r0. Further, the distance between the satellite position at the reference time t0 and the satellite position at the previous sample time is calculated, and the satellite velocity v0 at the reference time t0 is calculated from the calculated distance and the sample time interval.

Further, the IMES transmitter 5 does not transmit the positioning support information of all the GPS satellites 3, but the GPS satellites 3 (hereinafter referred to as “visible satellites”) that can be observed from the building or facility where the IMES transmitter 5 is installed. The positioning support information may be transmitted. In this case, the IMES transmitter 5 acquires a broadcast ephemeris of a visible satellite from the outdoor GPS receiver 7 illustrated in FIG. Then, using the acquired broadcast ephemeris, the positioning support information is generated for the visible satellites in the same manner as in the above-described embodiment, and the positioning support information is generated and transmitted.

In the above embodiment, the system is configured such that the IMES transmitter 5 directly communicates with the GNSS base station 6 to acquire the distribution ephemeris. However, the IMES transmitter 5 generates positioning support information and supports positioning. It is good also as interposing the delivery server 9 which performs the schedule management of transmission of information.

FIG. 5 is a diagram showing an example of the system configuration of the position calculation system 1100 in this case. However, in this drawing, the position calculation device 1 and the GPS satellite 3 are not shown. In the position calculation system 1100, a plurality of IMES transmitters 5 and a distribution server 9 are communicatively connected via a first network N1, and the distribution server 9 and a plurality of GNSS base stations 6 are connected via a second network N2. It is connected. The distribution server 9 and the first network N1 may be provided for each building or facility where the IMES transmitter 5 is installed, or may be provided for each fixed area, for example.

The distribution server 9 acquires the distribution ephemeris from the GNSS base station 6 via the second network N2. Then, using the acquired distribution ephemeris, positioning support information generation processing is performed in the same manner as in the above embodiment to generate positioning support information. Then, the generated positioning support information is transmitted to the IMES transmitter 5 via the first network N1, and the transmission timing and transmission schedule of the positioning support information by the IMES transmitter 5 are controlled.

The positioning support information transmitted from the distribution server 9 to the IMES transmitter 5 may be the positioning support information of all GPS satellites 3 or the positioning of visible satellites that can be observed from the building or facility where the IMES transmitter 5 is installed. It may be support information. In the latter case, for example, the location information of the building or facility where the IMES transmitter 5 is installed is stored in the distribution server 9 as a database, and the building where the IMES transmitter 5 is installed based on the location information stored in the database. What is necessary is to determine a visible satellite that can be observed from a facility or the like and generate positioning support information for the visible satellite.

6-4. Providing Ephemeris from IMES Transmitter In the above embodiment, IMES transmitter 5 has been described as transmitting positioning support information including the position and velocity of GPS satellite 3, but instead, broadcast ephemeris is transmitted. You may do it. The broadcast ephemeris transmitted by the IMES transmitter 5 can be acquired from the GNSS base station 6 or the distribution server 9.

In this case, the broadcast ephemeris transmitted from the IMES transmitter 5 may be the broadcast ephemeris of all GPS satellites 3 or the broadcast ephemeris of visible satellites.

Also, a submeter-class augmentation signal L1-SAIF (Submeter-class Augmentation with Integrity Function) signal is transmitted from the quasi-zenith satellite, which is an artificial satellite in the Japanese satellite positioning system. One of the information distributed by the current L1-SAIF signal is AFF (Almanac for First Fix). Therefore, for example, the AFF can be transmitted from the IMES transmitter 5.

6-5. 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 (estimates) 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.

6-6. Data content of positioning support information In the above embodiment, the positioning support information includes one position information and one speed information of the satellite position r0 and the satellite speed v0 at a certain reference time t0. Position information and speed information at a plurality of reference times may be included.

6-7. In the above-described embodiment, the position calculation apparatus 1 that acquires the ephemeris of the GPS satellite 3 and calculates the position has been described as an example. System), GALILEO, Beidou, and other GNSS satellites may be used.

1 position calculation device, 3 GPS satellite, 5 IMES transmitter, 6 GNSS base station, 7 outdoor GPS receiver, 8 precision calendar provision server, 9 distribution server, 10 antenna, 20 satellite signal receiver, 21 RF receiver circuit, 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, 1000, 1100 position calculation system.

Claims

A control method for a position calculating device, comprising:
Determining whether or not the positioning satellite orbit information stored in the storage unit satisfies a predetermined useful condition;
Executing a first acquisition process for acquiring the positioning support information from the ground communication device that transmits the positioning support information that is the basis of the calculation of the trajectory information when the determination result is negative;
Calculating the trajectory information using the acquired positioning support information, and updating the trajectory information stored in the storage unit;
Calculating the position of the position calculating device using a signal from the positioning satellite and orbit information stored in the storage unit;
Control method.
The orbit information includes at least one of 1) first orbit information calculated from the positioning support information and 2) second orbit information obtained by demodulating a signal from the positioning satellite. The
The control method according to claim 1.
Further comprising executing a second acquisition process for acquiring the orbit information by demodulating a signal from the positioning satellite when the first acquisition process fails.
The control method according to claim 1 or 2.
The ground communication device is a device that transmits the positioning support information in the same spread spectrum method as the positioning satellite using a spreading code different from the positioning satellite,
The acquisition is performed by switching the spreading code between reception of a signal from the ground communication device in the first acquisition process and reception of a signal from the positioning satellite in the second acquisition process. Including realizing,
The control method according to claim 3.
The positioning support information includes position and speed information and time information of the positioning satellite,
The orbit information is calculated using the equation of motion representing the motion of the satellite orbiting the earth, the position and velocity information of the positioning satellite included in the positioning support information, and the time information. Is to calculate
The control method according to any one of claims 1 to 4.
The storage unit stores an effective period of the trajectory information in association with the trajectory information,
The determining includes determining whether the useful condition is satisfied based on the validity period.
The control method according to any one of claims 1 to 5.
In the storage unit, a reliability index value of the trajectory information is stored in association with the trajectory information,
The determining includes determining whether the useful condition is satisfied based on a combination of the validity period and the reliability index value.
The control method according to claim 6.
A storage unit for storing orbit information of positioning satellites;
A determination unit that determines whether or not the trajectory information stored in the storage unit satisfies a predetermined useful condition;
When the determination result of the determination unit is a negative determination, an acquisition unit that acquires the positioning support information from the ground communication device that transmits the positioning support information that is the basis of the calculation of the trajectory information;
A calculation unit that calculates the trajectory information using the obtained positioning support information and updates the trajectory information stored in the storage unit;
A position calculation unit that calculates a position of the position calculation device using a signal from the positioning satellite and orbit information stored in the storage unit;
A position calculation device comprising: