JP2009109478A - Initial output positioning location determination method, program, positioning device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the accuracy of initially outputting positioned location and to improve the accuracy of initial output positioned location while suitably shortening TTFF according to the receiving environment. <P>SOLUTION: In the initial positioning, one or more times of positioning processing to compute the determined current location P are performed based on a caught GPS satellite signal. In this respective positioning processing, when the determined current location P and a time error T are calculated, it is determined whether the calculated determined current location P and time error T satisfy predetermined "altitude difference condition" and "convergence condition". When it is determined to satisfy at least one of the conditions, the determined current location P is outputted as an initial positioned location. After the initial positioned location is determined and outputted, the computed determined current location P is outputted as a positioned location for each positioning processing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an initial output positioning position determination method and the like for determining a positioning position to be output first after starting positioning.

  GPS (Global Positioning System) is widely known as a positioning system using an artificial satellite, and is used in a car navigation device or the like. In GPS, a GPS satellite signal is transmitted from each of a plurality of GPS satellites orbiting the earth orbit, and the GPS receiver calculates (positions) the current position based on the received GPS satellite signal.

By the way, the captured GPS satellite signal may include a GPS satellite signal that is affected by a multipath or the like. If a GPS satellite signal that is affected by a multipath or the like is used, The current position may not be accurately calculated (positioning). Therefore, a method for improving positioning accuracy by using an altitude table (city altitude information) is known in a multipath frequent occurrence area where buildings such as many high-rise buildings are lined up, for example, in central Tokyo. This altitude table is a data table in which an urban area having a small elevation difference is divided into a predetermined number (specifically, 9) of mesh areas, and altitudes corresponding to the mesh areas are determined (see, for example, Patent Document 1). ).
JP 2006-177773 A

  The GPS receiver repeatedly performs a positioning calculation for calculating the current position every predetermined time (for example, every second), and outputs the calculated current position as a positioning position. However, the first positioning position is output from the start of positioning. Until then, it usually requires multiple positioning calculations. If the TTFF is shortened between the time TTFF (Time to First Fix) and the positioning accuracy required from the start of positioning to the output of the first positioning position, the positioning accuracy decreases. Conversely, priority is given to improving the positioning accuracy. If it does, there exists a relationship that TTFF tends to become long. Which of the positioning accuracy and TTFF should be given priority depends on the reception environment. For example, in a reception environment with low overall positioning accuracy such as a multipath environment, positioning accuracy is given priority over shortening TTFF. After the Z count included in the GPS satellite signal is decoded and positioning accuracy is improved, the positioning position is It is preferable to output. On the other hand, since the positioning accuracy is high in the open sky environment, it is possible to prioritize the shortening of TTFF and output the positioning position without waiting for the decoding of the Z count.

  The present invention has been made in view of the above circumstances, and its object is to improve the accuracy of the first positioning position to be output. Another object is to achieve both shortening of the TTFF appropriate for the reception environment and improvement of the accuracy of the initial positioning position.

  A first invention for solving the above-mentioned problem is the first output positioning for performing a positioning calculation of the current position using a satellite signal transmitted from a positioning satellite and determining a positioning position to be output first after the positioning is started. A position determination method, which performs a positioning process using a received satellite signal to calculate a positioning position, and based on current and past positioning results each time the positioning process is performed. Determining whether or not a predetermined convergence condition is satisfied as a condition for determining that the positioning result of the positioning process repeatedly executed has converged, and if it is determined that the convergence condition is satisfied, An initial output positioning position determination method including determining a calculated positioning position as a positioning position to be output first.

  The tenth aspect of the invention includes a positioning calculation unit that performs a positioning calculation using a satellite signal transmitted from a positioning satellite and calculates a positioning position, and for each time the positioning process is performed, A convergence determination unit that determines whether or not a predetermined convergence condition is satisfied as a condition for determining that a positioning result of the positioning process that is repeatedly executed has converged based on past positioning results; and the convergence determination unit The positioning device includes an initial output positioning position determination unit that determines the positioning position calculated this time as the first output positioning position when it is determined that the convergence condition is satisfied.

  An eleventh aspect of the invention is an electronic apparatus including the positioning device of the tenth aspect of the invention.

  According to the first, tenth or eleventh invention, the positioning result of the positioning process is calculated every time the positioning process is performed by performing the positioning calculation using the satellite signal transmitted from the positioning satellite. It is determined whether or not a convergence condition that is a condition for determining convergence has been satisfied. And when it determines with satisfy | filling convergence conditions, the positioning position calculated this time is determined as a positioning position output first.

  For example, in a so-called multipath environment in which the received satellite signal includes satellite signals affected by multipath, etc., so-called multipath environment, the positioning accuracy tends to be low. It is highly possible that the convergence condition is not satisfied. That is, there is a high possibility that the convergence condition is not satisfied, and as a result, the positioning accuracy is prioritized over the shortening of TTFF. On the other hand, since the positioning accuracy is relatively high in the open sky environment, variation in positioning results in each positioning process is small, and there is a high possibility that the convergence condition is satisfied. That is, there is a high possibility that the convergence condition is satisfied, and as a result, TTFF can be shortened. As described above, when the convergence condition is satisfied, the calculated positioning position is determined as the initial output positioning position, so that the highly accurate initial output positioning position can be obtained, and an appropriate TTFF according to the reception environment can be obtained. Shortening is possible.

  The second invention is an initial output positioning position determination method according to the first invention, wherein a reference altitude corresponding to the two-dimensional position of the positioning position calculated this time is set as predetermined altitude information or predetermined every time the positioning process is performed. Determining whether the difference between the altitude of the positioning position calculated this time and the acquired reference altitude satisfies a predetermined altitude difference condition, and determining the positioning position The initial output positioning position determination method is to determine the positioning position calculated this time as the first output positioning position when it is determined that the altitude difference condition is satisfied and the convergence condition is determined It is.

  According to the second aspect of the invention, each time the positioning process is performed, it is further determined whether the difference between the currently calculated positioning position altitude and the predetermined reference altitude satisfies the predetermined altitude condition. When it is determined that the altitude condition is satisfied and the convergence condition is determined, the currently determined positioning position is determined as the positioning position to be output first.

  For example, in a multipath environment, since the positioning accuracy tends to be low, the difference between the calculated positioning position and the reference altitude is large, and there is a high possibility that the altitude difference condition is not satisfied. That is, there is a high possibility that neither the convergence condition nor the altitude difference condition is satisfied, and as a result, the positioning accuracy is prioritized over TTFF. On the other hand, in the open sky environment, since the positioning accuracy is relatively high, the difference between the calculated positioning position and the reference altitude is small, and there is a high possibility that the altitude difference condition is satisfied. Both are highly likely to be satisfied, and as a result, TTFF can be shortened. As described above, when both the convergence condition and the altitude difference condition are satisfied, the calculated positioning position is determined as the initial output positioning position, thereby making it possible to shorten the TTFF more appropriately according to the reception environment.

  A third aspect of the invention is an initial output positioning position determination method according to the second aspect of the invention, wherein the satellite signal reception environment is determined and the altitude difference condition is varied according to the determined reception environment. Is the first output positioning position determination method.

  According to the third aspect of the invention, the altitude difference condition is varied according to the satellite signal reception environment. If the altitude difference conditions are different, even if the positioning position is the same, the determination result of whether the altitude difference condition is satisfied differs, and as a result, the time from the start of positioning to the determination of the first positioning position to be output, that is, TTFF Is different. Also, if the reception environment is different, the positioning accuracy is different, and the difference between the positioning position altitude and the reference altitude is different, so the determination result of the altitude difference condition is different. For example, in a reception environment with relatively good positioning accuracy such as an open sky environment, the difference between the altitude of the positioning position and the reference altitude is small, and there is a high possibility that the altitude difference condition is satisfied. In a poor reception environment, the difference between the altitude of the positioning position and the reference altitude is large, and there is a high possibility that the altitude difference condition is not satisfied. That is, when the altitude difference condition is the same regardless of the reception environment, in the reception environment where the positioning accuracy is poor such as a multipath environment, the altitude difference condition is not easily satisfied, and the TTFF may become too long. For this reason, the determination of a more appropriate initial output positioning position is realized by varying the altitude difference condition according to the reception environment.

  A fourth invention is a first-time output positioning position determination method according to any one of the first to third inventions, wherein the reception environment of the satellite signal is determined, and according to the determined reception environment, An initial output positioning position determination method including changing a convergence condition.

  According to the fourth aspect of the invention, the convergence condition is varied according to the satellite signal reception environment. If the convergence condition is varied, even if the positioning result is the same, the determination result of whether the convergence condition is satisfied is different, and as a result, the TTFF is different. In addition, when the reception environment is different, since the dispersion of the positioning result is different due to the difference in positioning accuracy, the determination result of the convergence condition is different. For example, in a reception environment with relatively good positioning accuracy such as an open sky environment, there is a high possibility that the result of the positioning result is small and the convergence condition is satisfied. On the other hand, in a reception environment where the positioning accuracy is relatively poor, such as a multipath environment, there is a large possibility of satisfying the convergence condition due to large variations in positioning results. In other words, when the convergence condition is the same regardless of the reception environment, in a reception environment with poor positioning accuracy such as a multipath environment, the convergence condition is not easily satisfied, and the TTFF may become too long. For this reason, the determination of a more appropriate initial output positioning position is realized by varying the convergence condition according to the reception environment.

  A fifth invention is the first output positioning position determination method according to any one of the first to fourth inventions, wherein the determination as to whether the convergence condition is satisfied is performed by positioning processing before and after the positioning processing that is repeatedly executed. This is an initial output position determination method including determining the number of consecutive times when the calculated positioning position difference satisfies a predetermined short distance condition.

  According to the fifth invention, in determining whether the convergence condition is satisfied, the number of consecutive times that the difference between the positioning positions calculated in the positioning process before and after the repeatedly executed positioning process satisfies the predetermined short-distance condition Is included. Thereby, for example, by determining whether or not the convergence condition is satisfied based on whether or not the number of consecutive times satisfying the short distance condition exceeds a predetermined number, variation in positioning position along the time series is reduced. It is possible to determine that the convergence condition has been satisfied at the time when it is determined that it has converged.

  A sixth invention is an initial output positioning position determining method according to the fifth invention, wherein the reception environment of the satellite signal is determined, and the short distance condition is varied according to the determined reception environment. Is the first output positioning position determination method.

  According to the sixth aspect of the invention, the short distance condition is varied in accordance with the reception environment determined based on the received satellite signal. When the short distance condition is varied, even if the positioning result of the positioning process is the same, the determination result of whether the short distance condition is satisfied is different, and as a result, the determination result of whether the convergence condition is satisfied is different. Also, if the reception environment is different, the positioning result varies depending on the positioning accuracy, so the determination result of the short distance condition is different. For this reason, by determining the short-distance condition according to the reception environment, it is possible to determine a more appropriate initial output positioning position.

  The seventh invention is the first output positioning position determination method of any one of the first to sixth inventions, wherein executing the positioning process includes calculating a time error by the positioning process, Determining whether the convergence condition is satisfied includes determining an initial output position including determining the number of consecutive times that the difference in time error calculated in the positioning process before and after the positioning process that is repeatedly executed satisfies a predetermined approximate condition Is the method.

  According to the seventh aspect of the invention, the time error is further calculated by the positioning process, and in determining whether the convergence condition is satisfied, the difference between the time errors calculated in the positioning process before and after the repeatedly executed positioning process is determined. It includes determining the number of consecutive times that satisfies a predetermined approximate condition. Thereby, for example, by determining whether or not the convergence condition is satisfied based on whether or not the number of consecutive times satisfying the convergence condition exceeds a predetermined number, variation in time error along the time series is reduced. It can be determined that the convergence condition is satisfied when it is determined that (convergence has been achieved).

  An eighth invention is an initial output positioning position determination method according to the seventh invention, wherein the reception environment of the satellite signal is determined, and the approximation condition is varied according to the determined reception environment. Is an initial output positioning position determination method.

  According to the eighth aspect, the approximate condition is varied according to the reception environment determined based on the received satellite signal. When the approximation condition is varied, even if the positioning result of the positioning process is the same, the determination result of whether or not the approximation condition is satisfied is different, and as a result, the determination result of whether or not the convergence condition is satisfied is different. Also, if the reception environment is different, the variation in the positioning accuracy is different due to the difference in the positioning accuracy, so the determination result of the approximate condition is different. For this reason, the determination of a more appropriate initial output positioning position is realized by varying the approximation condition according to the reception environment.

  According to a ninth aspect of the present invention, there is provided an initial output positioning position determination method according to any one of the first to eighth aspects of the present invention in a computer built in a positioning apparatus that positions a current position using a satellite signal transmitted from a positioning satellite. Is a program for executing

  According to the ninth aspect, by causing the computer to read this program and executing the arithmetic processing, it is possible to achieve the same operational effects as any one of the first to eighth aspects.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following, an embodiment in which the present invention is applied to a mobile phone having a GPS positioning function will be described. However, the applicable embodiment of the present invention is not limited to this.

[First Embodiment]
First, the first embodiment will be described.
[Constitution]
FIG. 1 is a block diagram showing an internal configuration of the mobile phone 1 according to the first embodiment. According to FIG. 1, the mobile phone 1 includes a GPS antenna 10, a GPS receiving unit 20 that is a positioning device, a host CPU (Central Processing Unit) 61, an operation unit 62, a display unit 63, and a ROM (Read Only). Memory) 64, RAM (Random Access Memory) 65, a portable wireless communication circuit unit 70, and a portable antenna 80.

  The GPS antenna 10 is an antenna that receives an RF signal including a GPS satellite signal transmitted from a GPS satellite, and outputs the received RF signal.

  The GPS receiving unit 20 captures and extracts a GPS satellite signal from the RF signal received by the GPS antenna 10, and performs a positioning calculation based on a navigation message or the like extracted from the GPS satellite signal to calculate a current position. The GPS receiving unit 20 includes an RF (Radio Frequency) receiving circuit unit 21, an oscillation circuit 22, and a baseband processing circuit unit 30. The RF receiving circuit unit 21 and the baseband processing circuit unit 30 can be manufactured as separate LSIs (Large Scale Integration) or as a single chip.

  The RF reception circuit unit 21 multiplies the RF signal input from the GPS antenna 10 by a signal obtained by dividing or multiplying the oscillation signal input from the oscillation circuit 22, thereby multiplying the RF signal by an intermediate frequency signal (IF (Intermediate Frequency) signal), the IF signal is amplified, etc., converted into a digital signal by an A / D converter, and output. The oscillation circuit 22 is a crystal oscillator, for example, and generates and outputs an oscillation signal having a predetermined oscillation frequency.

  The baseband processing circuit unit 30 captures and tracks a GPS satellite signal from the IF signal input from the RF receiving circuit unit 21, decodes the data, and based on a navigation message, time information, etc. It is a circuit part which performs calculation calculation of this, positioning calculation, etc.

  Specifically, the GPS satellite signal is first captured based on the input IF signal. The acquisition of the GPS satellite signal is a process of extracting the GPS satellite signal from the IF signal, and performs a correlation process on the IF signal. Specifically, a coherent process for calculating the correlation between the IF signal and the pseudo-generated replica C / A code (code replica) using an FFT operation is performed, and a correlation value as a result of the coherent process is calculated. Incoherent processing is performed to calculate a correlation integrated value by integration. Thereby, the phase of the C / A code and the carrier frequency included in the GPS satellite signal is obtained.

  If the GPS satellite signal is acquired, then the acquired GPS satellite signal is tracked. The tracking of the GPS satellite signal is a process of performing synchronization holding of a plurality of captured GPS satellite signals in parallel. For example, a cold loop that is realized by a delay lock loop (DLL) and tracks the phase of the C / A code; For example, processing is performed with a carrier loop that is realized by a phase lock loop (PLL) and tracks the phase of the carrier frequency. Then, the data of each tracked GPS satellite signal is decoded to extract a navigation message, and a process of calculating (positioning) the current position by performing a pseudorange calculation, a positioning calculation, or the like is performed.

  The baseband processing circuit unit 30 includes a CPU 31, a ROM 40, and a RAM 50, and includes various circuits such as a replica C / A code generation circuit, a correlation calculation circuit, and a data decoding circuit.

  The CPU 31 comprehensively controls each unit of the baseband processing circuit unit 30 and each unit of the RF receiving circuit unit 21 and performs various arithmetic processes including a baseband process described later.

  In the baseband processing, the CPU 31 decodes the navigation message included in the captured and tracked GPS satellite signal, and calculates the current position based on the orbit information and time information of the GPS satellite included in the decoded navigation message. That is, from the difference between the transmission time of the GPS satellite signal from each GPS satellite and the reception time of the GPS satellite signal at the GPS receiver, the position of each GPS satellite at the time of transmission of the GPS satellite signal and each GPS from the GPS receiver Calculate the pseudorange to the satellite. Then, a simultaneous equation having four unknowns including the current position and the time error between the GPS satellite and the GPS receiver is set, and the current position is calculated by solving the simultaneous equations. At this time, the current position can be calculated by receiving GPS satellite signals from at least four or more GPS satellites. This is because four coordinate values (x, y, z) of the current position, which is a three-dimensional position, and the time error T of the GPS satellite and the GPS receiver are set as unknowns.

Further, the CPU 31 repeatedly performs a positioning process for calculating the current position at a predetermined time interval (for example, every one second). In the positioning process, a “satellite set” that is a combination of four or more GPS satellites is selected from the captured GPS satellite signals. For example, if eight GPS satellites signals captured, satellite set 163 pieces _{(= 8 C 8 + 8 C} 7 + 8 C 6 + 8 C 5 + 8 C 4) is selected. Next, for each selected satellite set, a positioning calculation using, for example, a least square method is performed to calculate the current position candidate and the time error candidate of the own aircraft. Then, for example, one of these satellite sets is selected according to a predetermined evaluation criterion, and the current position candidate of the selected satellite set is set as the current position P of the current determination, and the time error candidate of the satellite set is set as the current time candidate. Is determined as a time error T. The evaluation standard is realized by a known method such as a position accuracy degradation index PDOP (Position Dilution of Precision) based on the geometric arrangement of GPS satellites in the satellite set or a method based on the signal strength of each GPS satellite signal. Here, out of all the satellite sets generated from the captured GPS satellites, for example, dozens of satellite sets including 6 or more GPS satellites are extracted, and the positioning position and time for the extracted satellite sets are extracted. The error may be determined.

  In the first embodiment, when the positioning position is output for the first time (first positioning), the positioning process is performed once or more, and the determined current position P calculated in the last positioning process is output as the first positioning position ( Positioning output). After the first positioning position is determined, the calculated determined current position P is output as a positioning position (positioning output) for each positioning process.

  That is, in the first positioning, when the determined current position P and the time error T are calculated in each positioning process, the calculated determined current position P and the time error T satisfy the predetermined “altitude difference condition” and “convergence condition”, respectively. Judge whether to meet.

  The “altitude difference condition” is a condition relating to the calculated altitude z of the determined current position P, and is a condition for determining that the altitude difference between the altitude z and the reference altitude is small. Specifically, the CPU 31 refers to the “altitude table” and acquires the altitude z0 corresponding to the horizontal position (that is, the latitude and longitude, so-called two-dimensional position) of the current determined current position P. This altitude z0 is the “reference altitude”. The “altitude table” is a data table in which the altitude is defined for each area (divided area) obtained by dividing the earth's ground surface into a mesh shape. The divided area has a square rectangular shape and is defined so that each side of the square is oriented along the latitude direction or the longitude direction. Here, there are various types of altitude, such as an ellipsoidal height, an altitude above sea level, and an altitude.

  FIG. 2 shows an example of the altitude table 42. According to the figure, the altitude table 42 includes an area ID 42a that is an identification number of the divided area, a center position 42b, an area length 42c that is the length of each side, 42d is stored in association with each other. The center position 42b stores latitude and longitude.

  Next, the CPU 31 calculates a difference (altitude difference) Δz between the altitude z0 corresponding to the horizontal position of the determined current position P acquired from the altitude table 42 and the altitude z of the determined current position P, and calculates the calculated altitude difference Δz and A predetermined altitude difference threshold THz (for example, 200 [m]) is compared. If the altitude difference Δz is equal to or less than the altitude difference threshold THz, it is determined that “the altitude difference condition is satisfied”, and if it exceeds the altitude difference threshold THz, it is determined that “the altitude difference condition is not satisfied”.

  The “convergence condition” is a condition related to the result of the positioning process, and is a condition for determining that the determined current position P and the time error T, which are the positioning results, have converged. Specifically, the CPU 31 calculates a difference (positional difference) ΔP between the current determined current position P and the determined current position P0 calculated in the previous positioning process. If the calculated position difference ΔP is equal to or smaller than the position difference threshold THp (for example, 200 [m]), the position counter is incremented by “1” (counts up). If the position difference exceeds the position difference threshold THp, the position counter is cleared to zero. To do. Here, the position counter is cleared to zero at the start of positioning. That is, this position counter counts the number of times that the position difference ΔP has continuously reached the position difference threshold value THp.

  Further, a difference (time difference) ΔT between the current time error T and the time error T0 calculated in the previous positioning process is calculated. If the calculated time difference ΔT is equal to or less than the time difference threshold THt (for example, 0.02 [seconds]), the time counter is incremented by “1” (counting up), and if the time difference exceeds the time difference threshold THt, the time counter Is cleared to zero. Here, the time counter is cleared to zero at the start of positioning. That is, this time counter counts the number of times that the time difference ΔT is continuously equal to or less than the time difference threshold value THt.

  Next, the position counter value and the time counter value are respectively compared with a predetermined position counter threshold value THcp (for example, “5”) and a time counter threshold value THct (for example, “5”). If the position counter value is equal to or greater than the position counter threshold value THcp, or the time counter value is equal to or greater than the time counter threshold value THct, it is determined that the “convergence condition” is satisfied, and otherwise, the “convergence condition” is satisfied. judge.

  As a result, if it is determined that both the “altitude difference condition” and the “convergence condition” are satisfied, the current determination position P of this time is determined as the first positioning position, and is output to the host CPU 61 at the subsequent stage, for example. On the other hand, if at least one of the “altitude difference condition” and the “convergence condition” is not satisfied, the next positioning process is performed.

  By the way, after the Z count included in each subframe of the GPS satellite signal is decoded, the variation in the time error T becomes almost zero even in a multipath environment. For this reason, when the Z count is decoded, the determined current position P is determined and output as the first positioning position regardless of whether each of the “altitude difference condition” and the “convergence condition” is satisfied.

  The result of the positioning process by the CPU 31 is stored in the positioning result data 51. FIG. 3 shows an example of the data configuration of the positioning result data 51. According to the figure, the positioning result data 51 correlates the positioning time 51a, the calculated determined current position 51b, the time error 51c, and the output determination result 51d for each positioning process from the start of positioning. Storing. The output determination result 51d is a determination result of whether or not to output the determined current position as a positioning position.

  Further, the CPU 31 changes the above-described threshold values TH (the altitude difference threshold value THz, the position difference threshold value THp, and the time difference threshold value THt) according to the reception environment for each positioning process. The reception environment is determined based on, for example, the signal strength of the received GPS satellite signal or PDOP. Then, referring to the threshold value table 43, each threshold value TH is changed to a value corresponding to the determined reception environment.

  FIG. 4 shows an example of the threshold value table 43. According to the figure, the threshold value table 43 stores an altitude difference threshold value 43b, a position difference threshold value 43c, and a time difference threshold value 43d in association with each other for each reception environment 43a. Each threshold value TH is set to be smaller as the reception environment has better (higher) positioning accuracy. This is because the positioning accuracy differs depending on the reception environment. For example, the open sky environment has better positioning accuracy than other environments, and each error such as altitude difference Δz, time difference ΔT, and position difference ΔP is small, so each threshold value TH is set small. In the indoor environment, the positioning accuracy is worse than that in the open sky environment, and each of the errors is large. Therefore, each threshold value TH is set large.

  Returning to FIG. 1, the ROM 40 is a system program for the CPU 31 to control each unit of the baseband processing circuit unit 30 and the RF receiving circuit unit 21, various programs and data for realizing various processes including baseband processing, and the like. Is remembered. FIG. 5 shows an example of the configuration of the ROM 40. According to FIG. 5, the ROM 40 stores a baseband program 41 as a program, and an altitude table 42 and a threshold table 43 as data.

  The RAM 50 is used as a work area of the CPU 31, and temporarily stores programs and data read from the ROM 40, calculation results executed by the CPU 31 according to various programs, and the like. FIG. 6 shows an example of the configuration of the RAM 50. According to FIG. 6, positioning result data 51 is stored in the RAM 50.

  Returning to FIG. 1, the host CPU 61 comprehensively controls each unit of the mobile phone 1 according to various programs such as a system program stored in the ROM 64. Specifically, the telephone function as a telephone is mainly realized, and a navigation screen in which the current position of the mobile phone 1 input from the baseband processing circuit unit 30 is plotted on a map is displayed on the display unit 63. Processing for realizing various functions including a navigation function is performed.

  The operation unit 62 is an input device including operation keys, button switches, and the like, and outputs an operation signal corresponding to an operation by the user to the host CPU 61. By operating the operation unit 62, various instructions such as a positioning start / end instruction are input. The display unit 63 is a display device configured by an LCD (Liquid Crystal Display) or the like, and displays a display screen (for example, a navigation screen or time information) based on a display signal input from the host CPU 61.

  The ROM 64 stores a system program for the host CPU 61 to control the mobile phone 1 and various programs and data for realizing a navigation function. The RAM 65 is used as a work area of the host CPU 61, and temporarily stores programs and data read from the ROM 64, data input from the operation unit 62, calculation results executed by the host CPU 61 according to various programs, and the like.

  The portable antenna 80 is an antenna that transmits and receives radio signals for mobile phones to and from a radio base station installed by a communication service provider of the mobile phone 1. The portable wireless communication circuit unit 70 is a communication circuit unit for a mobile phone that includes an RF conversion circuit, a baseband processing circuit, and the like, and transmits and receives wireless signals under the control of the host CPU 61.

[Process flow]
FIG. 7 is a flowchart for explaining the flow of baseband processing executed by the CPU 31. This process is realized by the CPU 31 executing a process according to the baseband program 41. Prior to the baseband processing, the IF signal digitized through the reception of the RF signal by the GPS antenna 10 and the down-conversion of the IF signal by the RF reception circuit unit 21 is input to the baseband processing circuit unit 30. It shall be.

  According to FIG. 7, the CPU 31 performs a positioning calculation process to calculate the current determined current position P and the time error T (step A1). Subsequently, the reception environment is judged based on the received GPS satellite signal (step A5). Then, based on the determined reception environment, various threshold values are set according to the threshold value table 43 (step A7). Thereafter, count processing is performed to update the values of various counters (step A9).

  FIG. 8 is a flowchart for explaining the flow of the counting process. According to the figure, the CPU 31 calculates a difference (position difference) ΔP between the determined current position P calculated in the previous positioning process and the determined current position P calculated in the current positioning process (step B1). If the calculated position difference ΔP is equal to or smaller than the position difference threshold THp (step B3: YES), the position counter value is incremented by “1” (step B5), and if the position difference ΔP exceeds the position difference threshold THp (step B5). Step B3: NO), the position counter is cleared to zero (Step B7).

  Subsequently, it is determined whether or not the Z count has been decoded. If not decoded (step B8: NO), the time error T calculated in the previous positioning process and the time error T calculated in the current positioning process are determined. (Time difference) ΔT is calculated (step B9). If the time difference ΔT is less than or equal to the time difference threshold THt (step B11: YES), the time counter value is incremented by “1” (step B13), and if the time difference ΔT exceeds the time difference threshold THt (step B11). : NO), the time counter is cleared to zero (step B15). When the above process is performed, the count process is terminated.

  When the counting process is finished, the CPU 31 subsequently refers to the altitude table 42 to acquire the altitude z0 corresponding to the determined current position P (step A11), and acquires the acquired altitude z0 and the altitude z of the determined current position P. A difference (altitude difference) Δz is calculated (step A13). Next, the calculated altitude difference Δz is compared with the altitude difference threshold value THz. If the altitude difference Δz is less than the altitude difference threshold value THz (step A15: YES), the position counter value is compared with the position counter threshold value THcp. If the position counter value is equal to or greater than the position counter threshold value THcp (step A17: YES), the current position P determined this time is determined and output as the first positioning position (step A23).

  On the other hand, if the position counter value is less than the position counter threshold value (step A17: NO), it is determined whether or not the Z count has been decoded. If the Z count has been decoded (step A18: YES), the current determined position is determined and output as the first positioning position (step A23). If the Z count has not been decoded (step A18; NO), the time counter value is compared with the time counter threshold value THct. If the time counter value is equal to or greater than the time counter threshold value THct (step A19: YES), the current position P determined this time is determined and output as the first positioning position (step A23).

  On the other hand, if the time counter value is less than the time counter threshold value THct (step A19: NO) or the altitude difference Δz exceeds the altitude difference threshold value THz (step A15: NO), the current determination current position P is the first positioning position. (Step A21), the process returns to Step A1 to perform the next positioning. This is the first positioning.

  When the first positioning is completed, the CPU 31 subsequently performs the second and subsequent positioning. That is, a positioning calculation is performed to calculate the determined current position P (step A25), and the calculated determined current position P is output as a positioning position (step A27). Next, it is determined whether or not the positioning is to be ended. If the positioning is not to be ended (step A29: NO), the process returns to step A25 to perform the next positioning. On the other hand, if the positioning is finished (step A29: YES), the baseband processing is finished.

[Action / Effect]
Thus, according to the first embodiment, in the first positioning, the positioning process for calculating the determined current position P based on the captured GPS satellite signal is repeated one or more times. In each positioning process, when the determined current position P and time error T are calculated, it is determined whether the calculated determined current position P and time error T satisfy the predetermined “altitude difference condition” and “convergence condition”, respectively. If it is determined that at least one of the conditions is satisfied, the determined current position P is output as the first positioning position. Then, after the first positioning position is determined and output, the calculated determined current position P is output as the positioning position for each positioning process. Accordingly, it is possible to appropriately determine whether to give priority to the improvement of positioning accuracy or the shortening of TTFF according to the reception environment.

  That is, for example, in a reception environment with relatively low positioning accuracy such as a multipath environment, the difference between the calculated determined current position P and the reference altitude is large, and there is a high possibility that the altitude difference condition is not satisfied. There is a high possibility that positioning results will vary widely and the convergence condition will not be met. That is, there is a high possibility that both the altitude difference condition and the convergence condition are not satisfied, and as a result, the positioning accuracy is prioritized over the shortening of TTFF. On the other hand, in a reception environment with relatively high positioning accuracy such as an open sky environment, the difference between the calculated determined current position P and the reference height difference is small, and there is a high possibility that the height difference condition is satisfied. There is little possibility of meeting the convergence condition due to small variations in positioning results. That is, there is a high possibility that both the altitude difference condition and the convergence condition are satisfied, and as a result, TTFF can be shortened.

[Second Embodiment]
Next, a second embodiment will be described. However, in the following second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted or simplified.

[Constitution]
The configuration of the mobile phone in the second embodiment is the same as that of the mobile phone 1 in the first embodiment. And it differs from the above-mentioned 1st Embodiment by the point of determination with respect to decoding of Z count contained in each sub-frame of a GPS satellite signal. That is, as described above, after the Z count is decoded, the variation in the time error T becomes almost zero even in a multipath environment. For this reason, after the Z count is decoded, the determined current position P is determined and output as the initial positioning position regardless of whether each of the “altitude difference condition” and the “convergence condition” is satisfied. However, there are cases where there is no need to wait for Z count decoding due to differences in positioning accuracy depending on the reception environment. For example, since the positioning accuracy is better in the open sky environment than in other environments, the first positioning position may be output without waiting for the decoding of the Z count. On the other hand, in a multipath environment or an indoor environment, since the positioning accuracy is worse than that in the open sky environment, it is desirable to output the first positioning position after the Z count is decoded.

  That is, in the baseband processing, the CPU 31 refers to the Z count waiting table 44 and determines whether to wait for Z count decoding.

  FIG. 9 is a diagram illustrating an example of a data configuration of the Z count waiting table 44. According to the figure, the Z count wait table 44 stores a Z count decode wait flag 44b in association with each reception environment 44a. The Z count waiting flag 44b is set to “0” indicating that it is not necessary to wait for the decoding of the Z count in the open sky environment where the positioning accuracy is relatively good. In the reception environment where the positioning accuracy is relatively poor. In a certain multipath environment or indoor environment, “1” indicating that it is necessary to wait is set.

  FIG. 10 is a diagram illustrating an example of the configuration of the ROM 40B in the second embodiment. According to the figure, the ROM 40B stores a baseband program 41B as a program, and stores an altitude table 42, a threshold table 43, and a Z count waiting table 44 as data.

[Process flow]
FIG. 11 is a flowchart for explaining the flow of the baseband processing in the second embodiment. This process is realized by the CPU 31 executing a process according to the baseband program 41B.

  According to the figure, the CPU 31 performs a positioning calculation process to calculate the current determined current position P and the time error T (step A1). Subsequently, the reception environment is judged based on the received GPS satellite signal (step A5). Then, based on the received reception environment, various threshold values are set according to the threshold value table 43 (step A7). Thereafter, count processing (see FIG. 8) is performed to change the values of various counters (step A9).

  When the count process ends, the CPU 31 refers to the altitude table 42 to acquire the altitude z0 with respect to the determined current position P (step A11), and the difference between the acquired altitude z0 and the altitude z of the determined current position P (altitude) (Difference) Δz is calculated (step A13). Next, the calculated altitude difference Δz and the altitude difference threshold value THz are compared. If the altitude difference Δz is equal to or less than the altitude difference threshold value THz (step A15: YES), the position counter value is compared with the position counter threshold value THcp. If the position counter value is equal to or greater than the position counter threshold value THcp (step C17: YES), the time counter value is compared with the time counter threshold value THct. If the time counter value is equal to or greater than the time counter threshold value THct (step C19: YES), a Z count wait determination process is performed to determine whether to wait for the Z count decoding (step C21).

  FIG. 12 is a flowchart for explaining the flow of the Z count wait determination process. According to the figure, the CPU 31 first determines whether or not the Z count has been decoded. If the Z count has been decoded (step D1: YES), it is determined that the Z count is “not waited” for decoding (step D11).

  If the Z count has not been decoded (step D1: NO), the Z count wait flag corresponding to the reception environment is determined with reference to the Z count wait table 44. If the Z count wait flag is set to “0” (step D3: NO), it is determined that the Z count decoding is “not waited” (step D11).

  On the other hand, if the Z count waiting flag is set to “1” (step D3: YES), the elapsed time from the start of positioning is compared with a predetermined waiting time threshold value THw. Here, the waiting time threshold value THw is a threshold value of the time required for decoding the Z count. That is, since the Z count is decoded when one subframe is decoded, the waiting time threshold THw is set to a time (for example, about 7 to 10 seconds) longer than the subframe period of 6 seconds. .

  If the elapsed time is equal to or greater than the waiting time threshold value THw (step D5: YES), it is determined that the Z count is not to be decoded (step D11). On the other hand, if the elapsed time is less than the waiting time threshold THw (step D5: NO), it is determined whether or not the Z count can be decoded. Whether or not the Z count can be decoded is determined based on whether or not the GPS satellite signal used for positioning includes a signal having a high signal strength. Specifically, the SNR of each GPS satellite signal used for positioning is compared with a predetermined SNR threshold THs, and if the SNR of any signal is equal to or greater than the SNR threshold THs (step D7: YES), the Z count is decoded. Is determined to be “waiting” for decoding of the Z count (step D9). On the other hand, if the SNR of any GPS satellite signal is less than the predetermined SNR threshold value THs (step D7: NO), it is determined that the Z count cannot be decoded, and the Z count is determined not to be “waited” (step S7). Step D11). When the above processing is performed, the Z count determination processing ends.

  If it is determined in the Z count wait determination process that the Z count is not to be decoded (step C23: NO), the CPU 31 determines and outputs the current determined current position P as the initial positioning position (step C25). ). On the other hand, if it is determined to “wait” for the Z count decoding (step C23: YES), the positioning position is not output (step C27). Then, it returns to step A1 and performs the next positioning. This is the first positioning.

  When the first positioning is finished, it is subsequently determined whether or not the positioning is finished. If not finished (step C29: NO), the second and subsequent positioning are performed. That is, a positioning calculation is performed to calculate the determined current position P (step C31), and the calculated determined current position P is output as a positioning position (step C33). Then, it returns to step C29 and it is judged whether positioning is complete | finished. And if positioning is complete | finished (step C29: YES), a baseband process will be complete | finished.

[Action / Effect]
Thus, according to the second embodiment, it is determined whether to wait for the decoding of the Z count according to the reception environment. That is, in the open sky environment, the positioning accuracy is better in the open sky environment than in other environments, so the first positioning position may be output without waiting for the decoding of the Z count. On the other hand, in a multipath environment or an indoor environment, since the positioning accuracy is worse than that in the open sky environment, it is desirable to output the first positioning position after the Z count is decoded. Therefore, by determining whether to wait for the Z count decoding depending on the reception environment, it is possible to appropriately determine whether to give priority to the improvement of positioning accuracy or the shortening of TTFF according to the reception environment. Become.

[Modification]
It should be noted that the applicable embodiments of the present invention are not limited to the above-described two embodiments, and can of course be changed as appropriate without departing from the spirit of the present invention.

(A) Counter Threshold For example, in each of the above-described embodiments, the counter threshold is a fixed value (for example, “5”), but this may be changed according to the reception environment.

(B) Convergence condition In the above-described embodiments, the “convergence condition” is an OR condition of “the position counter value is equal to or greater than the position counter threshold THcp” or “the time counter value is equal to or greater than the time counter threshold THct”. This may be a combination condition of the position counter value and the time counter value. Specifically, for example, when the reception environment is “open sky environment”, “the sum of the counter values of the time counter and the position counter is“ 2 ”or more” is set as the “convergence condition”. When the reception environment is a “multipath environment”, the convergence condition is “the counter values of both the time counter and the position counter are“ 1 ”or more”.

(C) Acquisition of reference altitude Further, in each of the above-described embodiments, the reference altitude is acquired from the altitude table 42, but this may be configured to be acquired from the outside of the mobile phone 1 instead of the altitude table. . Specifically, for example, the position of the base station is received from the base station of the mobile phone 1 by the portable antenna 80, and it is determined whether the height difference condition is satisfied by using the height of the received position of the base station as a reference height. To do.

(D) Assist GPS
In each of the above-described embodiments, the current position is determined using only the received GPS satellite signal. However, the current position is determined as the initial position by receiving the base station position from the mobile base station. Alternatively, the positioning of the above-described embodiment may be performed using a so-called assist GPS function that performs positioning by receiving data such as ephemeris from a mobile base station.

(E) Host CPU
Further, part or all of the processing performed by the CPU 31 of the baseband processing circuit unit 30 may be performed by the host CPU 61 in software.

(F) Positioning device Further, in each of the above-described embodiments, a mobile phone, which is a kind of electronic device provided with a positioning device, has been described. For example, a portable navigation device, an in-vehicle navigation device, a PDA (Personal Digital Assistants) ) And other electronic devices such as wristwatches.

(G) Satellite Positioning System In the above-described embodiments, the case where GPS is used has been described, but it is needless to say that the present invention can be similarly applied to other satellite positioning systems such as GLONASS (GLObal Navigation Satellite System).

(H) Recording medium The baseband program 41 may be recorded on a recording medium such as a CD-ROM and installed in an electronic device such as a mobile phone.

The internal block diagram of the mobile telephone in 1st Embodiment. Example of data structure of altitude table. The example of a data structure of positioning result data. The data structural example of a threshold value table. The example of a structure of ROM. 2 is a configuration example of RAM. The flowchart of a baseband process. The flowchart of the count process performed during a baseband process. The data structural example of the Z count waiting table in 2nd Embodiment. The example of a structure of ROM. The flowchart of a baseband process. The flowchart of the Z count waiting determination process performed during a baseband process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile phone, 10 GPS antenna, 20 GPS receiving part, 21 RF receiving circuit part, 22 Oscillator circuit, 30 Baseband processing circuit part, 31 CPU, 40 ROM,
41 baseband program, 42 altitude table, 43 threshold table,
50 RAM, 51 Positioning result data

Claims (11)

An initial output positioning position determination method that performs a positioning calculation of a current position using a satellite signal transmitted from a positioning satellite and determines a positioning position to be output first after positioning starts,
Performing a positioning process by performing a positioning calculation using the satellite signal to calculate a positioning position;
Each time the positioning process is performed, based on the current and past positioning results, it is determined whether or not a predetermined convergence condition is satisfied as a condition for determining that the positioning result of the positioning process that is repeatedly executed has converged. And
When it is determined that the convergence condition is satisfied, the positioning position calculated this time is determined as a positioning position to be output first;
The first output positioning position determination method including Each time the positioning process is performed, a reference altitude corresponding to the two-dimensional position of the positioning position calculated this time is acquired from predetermined altitude information or a predetermined server, and the altitude of the positioning position calculated this time and the acquired reference altitude Further comprising determining whether the difference between the two satisfies a predetermined altitude difference condition,
Determining the positioning position is to determine the positioning position calculated this time as the first positioning position when it is determined that the altitude difference condition is satisfied and the convergence condition is determined to be satisfied. Is,
The initial output positioning position determination method according to claim 1. Determining the reception environment of the satellite signal;
Varying the altitude difference condition according to the determined reception environment;
The method for determining an initial output positioning position according to claim 2. Determining the reception environment of the satellite signal;
Varying the convergence condition according to the determined reception environment;
The first-time output positioning position determination method according to any one of claims 1 to 3.   The determination as to whether the convergence condition is satisfied includes determining a continuous number of times that a difference in positioning position calculated in a positioning process before and after the positioning process that is repeatedly executed satisfies a predetermined short distance condition. The initial output position determination method as described in any one of -4. Determining the reception environment of the satellite signal;
Varying the short distance condition according to the determined reception environment;
The method for determining an initial output positioning position according to claim 5. Executing the positioning process includes calculating a time error by the positioning process,
The determination as to whether or not the convergence condition is satisfied includes determining the number of consecutive times that the difference in time error calculated in the positioning process before and after the positioning process that is repeatedly executed satisfies a predetermined approximate condition. The initial output position determination method according to any one of claims 6 to 6. Determining the reception environment of the satellite signal;
Varying the approximation condition according to the determined reception environment;
The method for determining an initial output positioning position according to claim 7.   A computer built in a positioning device for positioning a current position using a satellite signal transmitted from a positioning satellite to execute the initial output positioning position determination method according to any one of claims 1 to 8. Program. A positioning calculation unit that performs a positioning process using a satellite signal transmitted from a positioning satellite to calculate a positioning position;
Each time the positioning process is performed, based on the current and past positioning results, it is determined whether or not a predetermined convergence condition is satisfied as a condition for determining that the positioning result of the positioning process that is repeatedly executed has converged. A convergence determination unit;
When it is determined by the convergence determination unit that the convergence condition is satisfied, an initial output positioning position determination unit that determines the positioning position calculated this time as the first output positioning position;
Positioning device equipped with.   An electronic device comprising the positioning device according to claim 10.

Images