JP2013190335A - Position calculation method and position calculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly perform switchover between long-term prediction orbital data and satellite orbital data acquired from a positioning satellite and further to improve accuracy of a position calculation at the time of the switchover.SOLUTION: First, a value of each parameter of hybrid orbital data is initially set by long-term prediction orbital data at the time of an initial position calculation. Then, a position calculation using the hybrid orbital data is performed while the value of each parameter of the hybrid orbital data is being updated by a value acquired every time a parameter of an ephemeris contained in a received GPS satellite signal (positioning signal) is acquired. When acquisition of the ephemeris is completed, the position calculation using the ephemeris is performed thereafter.

Description

  The present invention relates to a position calculation method and a position calculation apparatus.

  GPS (Global Positioning System) is widely known as a position calculation system using positioning signals, and is used in a position calculation device built in a mobile phone or the like. In the GPS, the position of the own device is calculated based on information such as the position of each of a plurality of GPS satellites and a pseudo distance that is a distance from each GSP satellite. In GPS position calculation, orbit data (almanac and ephemeris) superimposed on a GSP satellite signal (positioning signal) transmitted from a GPS satellite is acquired, and the position of each GPS satellite is calculated based on this. Almanac is information that indicates the approximate satellite orbit of all GPS satellites, but is generally not used for position calculation because the accuracy of the satellite orbit is low. On the other hand, the ephemeris is information indicating an accurate satellite orbit of the GPS satellite, and since the accuracy of the satellite orbit is high, this is used for position calculation.

  However, at the time of initial position calculation, for example, since the ephemeris is not held, it is necessary to acquire the ephemeris first, but this takes about several tens of seconds. Therefore, a configuration is known that connects to a server system that generates and provides long-term predicted ephemeris (long-term predicted orbit data), which is an ephemeris for a long period of time such as one week, and performs position calculation using the acquired long-term predicted orbit data (For example, refer to Patent Document 1).

JP 2010-066099 A

  However, the long-term predicted orbit data has a lower accuracy of the satellite orbit than the ephemeris acquired from the GPS satellite signal. For this reason, position calculation is performed using long-term predicted orbit data only until the ephemeris is acquired from the GPS satellite signal. When the ephemeris is acquired from the GPS satellite signal, the position calculation using this ephemeris is switched. Was normal. However, switching is not possible until the ephemeris is completely acquired, and the accuracy of position calculation before and after the switching changes, and so-called position jumps may occur.

  The present invention has been made in view of the above circumstances, and the object is to smoothly switch between long-term predicted orbit data and satellite orbit data acquired from a positioning satellite, and to calculate the position at the time of switching. Is to improve the accuracy.

  A first form for solving the above-described problem is that a positioning signal is received from a positioning satellite, and among parameters of satellite orbit data, a parameter whose value can be obtained from the received positioning signal is described above. A position calculation method including, using a value of long-term predicted trajectory data acquired in advance for a parameter for which a value could not be acquired from the received positioning signal. is there.

  As another form, a receiving unit that receives a positioning signal from a positioning satellite, and among parameters of satellite orbit data, the parameter that can be obtained from the received positioning signal is the obtained value. A position calculation unit including a position calculation unit that calculates a position using a value of long-term predicted trajectory data acquired in advance for a parameter for which a value cannot be acquired from the received positioning signal. May be.

  According to the first embodiment, among the parameters of the satellite orbit data, the acquired value is used for the parameter that can be acquired from the received positioning satellite signal, and the parameter that cannot be acquired is acquired in advance. The position is calculated using the long-term predicted orbit data. In other words, when all the parameters of the satellite orbit data have not been received, the parameters of the long-term predicted orbit data acquired in advance and the parameters of the satellite orbit data included in the received positioning satellite signal are used. Position calculation is performed.

  Position calculation using satellite orbit data acquired from a positioning satellite is more accurate than position calculation using long-term predicted orbit data. For this reason, immediately after the start of receiving the positioning signal, the position calculation using the parameters of the long-term predicted orbit data is performed, but the satellite orbit among the parameters of the orbit data used for position calculation in accordance with the reception of the satellite orbit data. The ratio of data parameters is increased, and the accuracy of position calculation is expected to be improved. Therefore, since it is possible to start position calculation using long-term predicted orbit data without waiting for reception of all parameters of satellite orbit data, it is possible to smoothly switch satellite orbit data and until all are received. The accuracy of position calculation during the period can be improved.

  Further, as a second mode, the position calculation method according to the first mode further includes detecting reception of all parameters of the satellite orbit data, and performing the position calculation includes: You may comprise the position calculation method including performing position calculation using the parameter of the said satellite orbit data received.

  According to the second aspect, after receiving all the parameters of the satellite orbit data, the position calculation is performed using the parameters of the received satellite orbit data.

  Further, as a third mode, the position calculation method according to the first or second mode, wherein the position calculation includes a reference time of the long-term predicted orbit data and a reference time of the received satellite orbit data. , The position calculation method including correcting the parameter of the long-term predicted orbit data to a value suitable for the reference time of the satellite orbit data may be configured.

  According to the third embodiment, when the reference time of the long-term predicted orbit data is different from the reference time of the received satellite orbit data, the parameters of the long-term predicted orbit data are adapted to the reference time of the satellite orbit data. It is corrected to the value. In a state where the parameters of the long-term predicted orbit data and the parameters of the satellite orbit data are used in combination, the accuracy of position calculation may be reduced if the reference times of both orbit data are different. For this reason, when the reference time is different, it is possible to prevent a decrease in the accuracy of position calculation by correcting the parameters of the long-term predicted orbit data in accordance with the reference time of the satellite orbit data with good position calculation accuracy. .

The block diagram of the mobile telephone in embodiment. The functional block diagram of a baseband process circuit part. Data configuration example of hybrid orbit data. The flowchart of a baseband process. The flowchart of the baseband process in a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the applicable embodiment of the present invention is not limited to this.

[Constitution]
FIG. 1 is a block diagram illustrating an example of an internal configuration of the mobile phone 1 according to the present embodiment. The mobile phone 1 includes a GPS antenna 10, a GPS 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, a storage unit 35, and a mobile phone. Wireless communication circuit unit 40 and mobile phone antenna 50.

  The GPS antenna 10 is an antenna that receives an RF (Radio Frequency) signal including a GPS satellite signal transmitted from a GPS satellite. The GPS satellite signal is a 1.57542 [GHz] communication signal modulated by a CDMA (Code Division Multiple Access) method, which is a type of spread spectrum method, by a C / A (Coarse and Acquisition) code, which is a type of spreading code. It is. 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.

  The GPS receiver 20 measures the position of the mobile phone 1 based on the signal received by the GPS antenna 10. The GPS receiving unit 20 includes an RF receiving circuit unit 21 and a baseband processing circuit unit 22. 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 and corresponds to a receiving unit that receives a positioning signal. As the circuit configuration, for example, an RF signal received by the GPS antenna 10 may be converted into a digital signal by an A / D converter and the digital signal may be processed, or may be received by the GPS antenna 10. Alternatively, the RF signal may be processed as an analog signal and finally A / D converted to output a digital signal to the baseband processing circuit unit 22.

  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 GPS 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. After being equalized, it 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 GPS satellite signal by performing carrier removal and correlation processing on the signal received by the RF receiving circuit unit 21. Based on satellite orbit data such as ephemeris extracted from the GPS satellite signal, time data, and the like, a predetermined position calculation is performed to calculate the position (positional coordinates) of the mobile phone 1 and a clock error.

  The host processing unit 30 is realized by an arithmetic device such as a CPU, for example, and comprehensively controls each unit of the mobile phone 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 call request, a mail transmission / reception request, and 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 mobile phone 1 and includes an oscillation circuit such as a crystal oscillator.

  The storage unit 35 is realized by a storage device such as a ROM or a RAM, for example, and the system program for the host processing unit 30 to comprehensively control the mobile phone 1, the various programs and data for executing various application processes, and the like. Remember.

  The mobile phone wireless communication circuit unit 40 is a mobile phone communication circuit unit configured by an RF conversion circuit, a baseband processing circuit, and the like. Realize transmission and reception. The cellular phone antenna 50 is an antenna that transmits and receives cellular phone radio signals to and from a radio base station installed by a communication service provider of the cellular phone 1.

  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 device such as a CPU or a DSP, 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. In addition, the processing unit 100 includes a satellite capturing unit 110 and a position calculating unit 120.

  The satellite capturing unit 110 captures GPS satellite signals. First, a GPS satellite to be captured (capture target satellite) is selected. Specifically, at the current time measured by the clock unit 34, a GPS satellite located in the sky at a given reference position is determined using previously acquired almanac or long-term predicted orbit data 220, and the satellite to be captured is acquired. And The reference position is, for example, the position acquired by server assist in the case of the first position calculation after power-on, and the latest calculated position in the second and subsequent position calculations.

  Next, the GPS satellite signal is captured for each capture target satellite. That is, the capture target satellite is captured by performing a correlation operation using the replica C / A code corresponding to the capture target satellite on the reception signal output from the RF reception circuit unit 21. Next, carrier removal is performed on the captured GPS satellite signal, and decoding of the navigation message included in the GPS satellite signal is started. Then, the ephemeris included in the decoded navigation message is stored as the received trajectory data 230, and the hybrid trajectory data 240 is updated by this ephemeris. That is, the ephemeris includes a plurality of parameters, but each time one parameter is acquired, the value of the corresponding parameter in the hybrid trajectory data 240 is updated with the acquired value.

  FIG. 3 is a diagram illustrating an example of a data configuration of the hybrid trajectory data 240. The hybrid orbit data 240 is generated for each GPS satellite, and stores a satellite ID 241 that is an identification number of the corresponding GPS satellite and ephemeris data. The ephemeris data stores a setting value 243 and an update flag 244 in association with each parameter 242. Initially, the setting value 243 stores the value of the corresponding parameter of the long-term predicted orbit data 200, and is sequentially updated by receiving the GPS satellite signal and decoding the ephemeris. The update flag 244 is a flag indicating whether or not the value of the corresponding parameter has been updated with a value acquired from the received GPS satellite signal.

  The position calculation unit 120 calculates the position of the mobile phone 1. Specifically, when the number of GPS satellites captured by the satellite capturing unit 110 reaches a predetermined number (for example, 4 or more) capable of position calculation, position calculation using the hybrid orbit data 240 of each captured satellite. Calculation is performed to calculate the position of the mobile phone 1. Thereafter, when the ephemeris is completely acquired for each of the acquisition target satellites (that is, when the setting values of all the parameters of the hybrid orbit data 240 are updated), thereafter, the received orbit data of each of the acquisition target satellites is acquired. A position calculation operation using 230 (that is, an ephemeris acquired from a GPS satellite signal) is performed. The position calculated by the position calculation unit 120 is accumulated and stored as calculated position data 260 in association with, for example, a calculation time.

  The storage unit 200 is realized by a storage device such as a ROM or a RAM, and stores a system program for the processing unit 100 to control the baseband processing circuit unit 22 in an integrated manner, a program and data for realizing various functions, and the like. In addition to being stored, it is used as a work area for the processing unit 100, and temporarily stores calculation results and the like executed by the processing unit 100 according to various programs. In the present embodiment, a baseband processing program 210, reception trajectory data 230, long-term predicted trajectory data 220, hybrid trajectory data 240, measurement information 250, and calculated position data 260 are stored.

  The long-term predicted orbit data 220 is GPS satellite orbit data for a predetermined period, and is generated for each GPS satellite. The ephemeris, which is orbit data included in the GPS satellite signal, has an effective period as short as about 2 to 4 hours, whereas the long-term predicted orbit data 220 has an effective period of, for example, 2 to 7 days. It is data. The long-term predicted orbit data 220 is acquired by connecting to the Internet from the mobile phone 1, for example, and periodically downloading it from an external server that generates and provides long-term predicted data. In the present embodiment, the long-term predicted orbit data 220 is described as a type of ephemeris acquired from an external server, but may be an almanac acquired from a GPS satellite.

  The reception orbit data 230 is data for each GPS satellite, and is ephemeris data acquired from the corresponding GPS satellite signal.

[Process flow]
FIG. 4 is a flowchart illustrating the flow of baseband processing. This processing is processing executed by the processing unit 100 in accordance with the baseband processing program 210.

  First, the processing unit 100 determines whether or not the long-term predicted trajectory data 220 is held (step A1). If it is held (step A1: YES), it is determined whether this long-term predicted orbit data 220 is within the valid period (step A3). If the long-term predicted orbit data 220 is not held (step A1: NO), or if it is held but outside the valid period (step A3: NO), for example, a predetermined external server is connected via the network. By connecting and downloading, long-term predicted orbit data is acquired (step A5).

  Subsequently, the processing unit 100 initializes the hybrid orbit data 240 by setting each parameter of the long-term predicted orbit data 220 as a parameter of the corresponding hybrid orbit data 240 for each GPS satellite (step A7). Next, the satellite capturing unit 110 selects a GPS satellite to be captured (step A9). Then, acquisition processing for each selected acquisition target satellite is performed in parallel.

  In the acquisition process, first, acquisition of a corresponding GPS satellite signal is started (step A11). If acquisition is successful (step A13: YES), measurement information (code phase and reception frequency) of the GPS satellite is acquired (step A15), and then decoding of the navigation message is started (step A17). . Then, the hybrid trajectory data 240 is updated with the ephemeris included in the acquired navigation message (step A19). Here, the ephemeris does not have to be completely acquired, and each time one parameter of the ephemeris is acquired, the parameter value in the hybrid trajectory data 240 is updated with the acquired value.

  Subsequently, when the number of captured GPS satellites (the number of captured satellites) reaches a number (for example, 4 or more) capable of position calculation (step A21: YES), the position calculation unit 120 determines that the hybrid orbit data Position calculation using 240 is performed. That is, for each captured satellite, the satellite position is calculated based on the corresponding hybrid orbit data 240 (step A23). Then, position calculation processing using these satellite positions is performed to calculate the position of the mobile phone 1 (step A25), and the calculated position is displayed on the display unit 32, for example (step A27).

  Subsequently, it is determined whether or not the acquisition of the navigation message has been completed for all the capture target satellites. If not completed (step A29: NO), the process returns to step A15 and the same processing is repeated.

  On the other hand, if acquisition of the navigation message is completed for all the capture target satellites (step A29: YES), the position calculation unit 120 performs position calculation using the received orbit data 230. That is, for each captured satellite, the satellite position is calculated based on the corresponding received orbit data 230 (step A31). Then, position calculation processing using these satellite positions is performed to calculate the position of the mobile phone 1 (step A33), and the calculated position is displayed on the display unit 32, for example (step A35).

  Thereafter, the processing unit 100 determines whether or not to end the process. If not (step A37: NO), the processing unit 100 returns to step A31. If the process ends (step A37: YES), the baseband process ends.

[Function and effect]
According to the present embodiment, when calculating the initial position, first, the values of the parameters of the hybrid trajectory data 240 are initially set by the long-term predicted trajectory data 220. Each time an ephemeris parameter included in the received GPS satellite signal (positioning signal) is acquired, the value of the parameter in the hybrid orbit data 240 is updated with the acquired value, and the hybrid orbit data 240 is used. The calculated position is performed. When the acquisition of the ephemeris is completed, position calculation using the acquired ephemeris (reception trajectory data 230) is performed thereafter.

  That is, until the ephemeris included in the GPS satellite signal is completely acquired, position calculation is performed using orbit data in which the acquired ephemeris parameter values and long-term orbit prediction data parameter values are mixed. . More specifically, among the plurality of parameters of the ephemeris, the received value is preferentially used for the received parameter, but for the parameter that has not been acquired, the value of the long-term predicted orbit data 220 is used. Thereby, it is possible to smoothly switch from position calculation using the long-term predicted orbit data 220 to position calculation using the ephemeris included in the GPS satellite signal, and to improve the accuracy of position calculation at the time of switching. Is possible.

[Modification]
It should be noted that embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

(A) Correction of long-term predicted orbit data 220 In the above-described embodiment, the value of each parameter of the hybrid orbit data 240 used for position calculation is the value of the ephemeris acquired from the GPS satellite signal and the long-term predicted orbit data 220. Although the values are mixed, if the reference times of both trajectory data are different, the accuracy of position calculation may be greatly reduced.

  That is, the parameter of the trajectory data is configured so that the trajectory position at the specified time can be calculated based on the time difference between the reference time and the specified time (current time). For this reason, if the parameter values of the orbit data having different reference times are used in combination, the accuracy of position calculation may be greatly reduced.

  Therefore, when the ephemeris reference time acquired from the GPS satellite signal is different from the reference time of the long-term predicted orbit data 220, the values of the parameters of the long-term predicted orbit data 220 are corrected to match the ephemeris reference time. To do. Specifically, according to Kepler's elliptical orbit model, which is one of the approximate models of the satellite orbit, the parameters of the model formula (satellite orbit parameters) with the same reference time as the ephemeris reference time are calculated.

  FIG. 5 is a flowchart for explaining the processing when this correction is performed. In the baseband processing (see FIG. 4) in the above-described embodiment, the hybrid orbit data 240 is updated by the ephemeris acquired from the GPS satellite signal (step A19), and then the following processing is performed.

  That is, it is determined whether or not the reference time is acquired as an ephemeris parameter, and if it is acquired (step B1: YES). The acquired reference time of the ephemeris is compared with the reference time of the long-term predicted orbit data 220 (step B3).

  As a result, if the two reference times do not match (step B5: NO), the values of the parameters of the long-term predicted orbit data 220 are corrected in accordance with the ephemeris reference time (step B7). Next, of the parameters of the hybrid trajectory data 240, the value of the parameter not updated with the value of the ephemeris (that is, the update flag is “0”) is updated with the value of the corrected long-term predicted trajectory data 220 (step B9). ).

(B)
In the above-described embodiment, the case where the present invention is applied to a mobile phone which is a kind of electronic device has been described, but the embodiment to which the present invention can be applied is not limited thereto. For example, the present invention can be similarly applied to other electronic devices such as a car navigation device, a portable navigation device, a personal computer PDA (Personal Digital Assistant), and a wristwatch.

(C)
In the above embodiment, the GPS has been described as an example of the satellite positioning system. The satellite positioning system may be used.

1 cellular phone, 10 GPS antenna, 20 GPS receiver, 21 RF receiver circuit, 22 baseband processor, 30 host processor, 31 operation unit, 32 display unit, 33 sound output unit, 34 clock unit, 35 storage unit 40 mobile phone wireless communication circuit unit 50 mobile phone antenna 100 processing unit 110 satellite acquisition unit 120 position calculation unit 200 storage unit 210 baseband processing program 220 long-term predicted orbit data 230 received orbit data , 240 Hybrid orbit data, 250 measurement information, 260 Calculated position data

Claims (4)

Receiving positioning signals from positioning satellites;
Among the parameters of the satellite orbit data, the acquired value is obtained for the parameter that can be obtained from the received positioning signal, and the parameter that is not obtained from the received positioning signal is obtained in advance. Calculating the position using the value of the long-term predicted orbit data,
Position calculation method including Detecting reception of all parameters of said satellite orbit data;
Performing the position calculation includes performing position calculation using the parameters of the received satellite orbit data after the detection.
The position calculation method according to claim 1. Performing the position calculation means that if the reference time of the long-term predicted orbit data is different from the reference time of the received satellite orbit data, the parameter of the long-term predicted orbit data is set to the reference time of the satellite orbit data. Including correction to a suitable value,
The position calculation method according to claim 1 or 2. A receiving unit for receiving a positioning signal from a positioning satellite;
Among the parameters of the satellite orbit data, the acquired value is obtained for the parameter that can be obtained from the received positioning signal, and the parameter that is not obtained from the received positioning signal is obtained in advance. A position calculation unit that calculates a position using the value of the long-term predicted orbit data,
A position calculation device comprising:

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