JP2012021808A - Position finding support apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position finding support apparatus that makes possible, in a receiver device of a position finding system to which satellite navigation is applied, quick identification of the speed or position of a navigation satellite applied to position finding, and realize starting of highly accurate position finding at low cost without requiring substantial alteration of hardware or software.SOLUTION: A position finding support apparatus that figures out under feedback control physical quantities pertaining to a navigation satellite to be newly applied to position finding is provided with estimation means that estimates a convergence value of physical quantities substituted as roots of simultaneous equations into an equation representing a transitional response of the feedback control of a sequence of the physical quantities figured out according to sailing data having arrived in a sequence of time series from the navigation satellite, and position finding accelerating means that applies the convergence value to the position finding.

Description

  The present invention relates to a positioning support apparatus capable of promptly identifying the speed or position of a navigation satellite applied to positioning in a positioning system receiving apparatus to which satellite navigation is applied.

GPS (Global
Many GNSS (Global Navigation Satellite Systems) receivers, including Positioning System, have a pseudo-distance acquisition, DLL (Delay Lock Loop), and AFC (Automatic Frequency Control) that realizes the tracking of the carrier wave frequency and phase of the received wave. ), A feedback control system such as PLL (Phase Locked Loop) is incorporated.

  In such a receiving apparatus, for the purpose of ensuring the desired positioning accuracy, for example, any GPS satellite to be newly applied to positioning after starting or in a steady state, a time constant specific to the feedback control system. The distance and the speed are identified as values at the time of waiting until the transient response corresponding to the value converges with a desired accuracy (≈ideal convergence value).

  As a prior art related to the present invention, as described in Patent Document 1 described later, “the initial position calculation time (TTFF) for determining the position of the GPS receiver is reduced using backup navigation data”. A non-volatile storage unit for storing the backup navigation data and communicates with the non-volatile storage unit so that information can be exchanged between the non-volatile storage unit and the backup navigation data. And the local time reference is calculated without using an RTC circuit when the GPS receiver is turned on, and the GPS reception is performed using the backup navigation data and the local time reference. A positioning unit having a function of reducing the TTFF during the position determination period for the device By providing a GPS receiver capable of calculating a local time reference without using an RTC circuit and storing backup navigation data using a non-volatile storage unit, the local time reference and backup navigation data are There is a receiver characterized in that the TTFF of the GPS receiver can be reduced.

JP 2008-197084 A

By the way, in the above-described conventional example, since the time required for convergence of the transient response is as long as several seconds, it occupies most of the time TTFF (Time to First Fix) required for starting the positioning from the start.
However, in recent years, the use and needs of positioning systems using GPS and the like have been diversified, and there is a strong demand for a significant shortening of the TTFF particularly in application systems incorporated in mobile phone terminals incorporating GPS receivers. .

  As shown in FIG. 4B, the positioning result started before the transient response sufficiently converges generally involves an error of several tens of meters to several hundreds of meters. Therefore, there has been a strong demand for a technique that can shorten the TTFF without lowering the positioning accuracy.

  An object of the present invention is to provide a positioning support device that can realize the start of positioning with high accuracy at low cost without significantly changing the configuration of hardware or software.

According to the first aspect of the present invention, in the positioning support apparatus for obtaining a physical quantity relating to a navigation satellite newly applied for positioning under feedback control, the estimating means is adapted to the navigation data arriving in time series from the navigation satellite. The convergence value of the physical quantity is estimated as the root of the simultaneous equation in which the column of the physical quantity obtained accordingly is substituted into an expression indicating a transient response of the feedback control. The positioning promoting means applies the convergence value to the positioning.
That is, the convergence value applied to positioning is quickly estimated by an arithmetic operation performed before the transient response of the feedback control converges.

According to the second aspect of the present invention, in the positioning support apparatus for obtaining a physical quantity relating to a navigation satellite newly applied for positioning under feedback control, the estimating means is adapted to the navigation data arriving in time series from the navigation satellite. As a root of a plurality of N sets of simultaneous equations in which the column of the physical quantity obtained in response is substituted into an expression indicating a transient response of the feedback control, N candidates of the convergence value of the velocity are obtained, and the N Among the candidates, a specific candidate having the smallest error or falling below a predetermined threshold is estimated as the convergence value. The positioning promoting means applies the specific candidate to the positioning.
That is, the convergence value applied to positioning is estimated quickly and accurately by an arithmetic operation performed before the transient response of the feedback control converges.

According to a third aspect of the present invention, in the positioning support apparatus according to the first or second aspect, the physical quantity is a speed of the navigation satellite.
That is, even when the physical quantity applied for positioning is the speed of the navigation satellite, the convergence value of the speed is estimated quickly and accurately by the arithmetic operation described above.

According to a fourth aspect of the present invention, in the positioning support apparatus according to the first or second aspect, the physical quantity is a distance of the navigation satellite.
That is, even when the physical quantity applied to positioning is the distance of the navigation satellite, the convergence value of the distance is estimated quickly and accurately by the arithmetic operation described above.

According to a fifth aspect of the present invention, in the positioning support device according to any one of the first to fifth aspects, the equation is an approximate equation that approximates the transient response.
That is, the arithmetic operation performed to calculate the convergence value is realized at high speed without unnecessarily increasing the processing amount within the accuracy range of the approximate expression.

In the positioning system to which the present invention is applied, not only at the time of start-up, but also when the number of navigation satellites to be applied for positioning increases, the responsiveness is improved without reducing the positioning accuracy.
In addition, the positioning system to which the present invention is applied improves responsiveness while maintaining high positioning accuracy even when starting and when the number of navigation satellites to be applied for positioning increases.

Furthermore, the positioning system to which the present invention is applied has improved positioning response.
Further, according to the positioning system to which the present invention is applied, both desired accuracy and responsiveness can be obtained.

  Therefore, according to the present invention, positioning is performed accurately and stably even when the propagation path of radio signals coming from navigation satellites is frequently blocked, and the results of positioning can be applied to various fields. It becomes possible.

It is a figure which shows one Embodiment of this invention. It is an operation | movement flowchart of the signal processing part in this embodiment. It is a figure explaining operation | movement of this embodiment. It is a figure which shows the subject of a prior art example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of the present invention.
In the figure, the antenna terminal of the radio unit 12 is connected to the feeding point of the antenna 11 from which a radio signal comes from a GPS satellite (not shown), and the output of the radio unit 12 is connected to the input of the signal processing unit 13. The The output of the signal processor 13 includes the position of the GPS satellite (hereinafter referred to as “satellite position”), distance (hereinafter referred to as “satellite distance”) speed (hereinafter referred to as “satellite speed”), acceleration ( Hereinafter, all or part of “satellite acceleration”) is output.

FIG. 2 is an operation flowchart of the signal processing unit in the present embodiment.
FIG. 3 is a diagram for explaining the operation of the present embodiment.
The operation of this embodiment will be described below with reference to FIGS.

The basic operation of each part of this embodiment is as follows.
The radio unit 12 generates an intermediate frequency signal by detecting a received wave arriving at the antenna 11 from a GPS satellite, and generates a digital signal by A / D converting the intermediate frequency signal.

The signal processing unit 13 performs the following processing.
(1) GPS satellites are sequentially selected based on a predetermined algorithm, the Doppler shift of the received wave is estimated for each selected GPS satellite, and the received wave in a predetermined frequency band including the center value of the Doppler shift is Take correlation.
(2) Among the C / A codes that can be received from the GPS satellites in parallel, the frequency that maximizes the correlation with the C / A code received from the corresponding GPS satellite and the phase of the C / A code are detected. To capture GPS satellites.

(3) For any GPS satellite, after the acquisition is completed, tracking of the carrier wave and the phase of the C / A code is continued.
(4) By measuring the phase of the C / A code received from the GPS satellite, the time when the received wave was transmitted (hereinafter referred to as “transmission time”) is obtained.

(5) Deviation from “transmission time” of “time given by a clock (hereinafter,“ built-in clock ”) built in the GPS receiver according to the present embodiment (hereinafter, simply“ receiver ”). Is obtained as the required propagation time T of the received wave coming from the corresponding GPS satellite.
(6) The pseudo distance of the GPS satellite is obtained as the product of the required propagation time T and the nominal value C of the propagation speed of the received wave.

(7) By demodulating the received wave, almanac (including rough orbit information of all GPS satellites in orbit) and ephemeris (clock correction coefficient and orbit information of the GPS satellite from which the received wave is transmitted) Including).
(8) The satellite position of each GPS satellite in the three-dimensional coordinate system with the center of the earth as the origin is obtained based on the ephemeris.

(9) Among these GPS satellites, for four or more GPS satellites, as a solution of simultaneous equations established for the “satellite position” and “pseudorange” at the “transmission time”, The position (X, Y, Z) and the deviation of the time given by the “built-in clock” of the receiver are obtained, and these position and deviation are output.

  The features of this embodiment are “satellite distance” and “satellite speed” calculated based on almanac and ephemeris in the process of the above-described processes (1) to (9) (hereinafter referred to as “positioning process”). Among these physical quantities, the physical quantity to be applied to the subsequent positioning process is determined based on the procedure described later.

  Note that the process of simply calculating the physical quantity from the radio signal arriving from a GPS satellite is not a feature of the present invention, and can be realized using various known techniques, and therefore the description thereof is omitted here.

  When the signal processing unit 13 identifies a GPS satellite to be applied to the positioning process after start-up or a GPS satellite to be newly applied to the positioning process, the “satellite distance”, “satellite speed”, and the like of the corresponding GPS satellite Are appropriately calculated in the order of time series.

  The physical quantity is calculated by the presence of a feedback control system (not shown) incorporated in the radio unit 12 and the signal processing unit 13 and linked under a predetermined function distribution or load distribution. Such a feedback system corresponds to, for example, the above-described DLL, AFC, PLL, or the like.

  Therefore, the physical quantity V calculated in the order of the time series t in cooperation with the feedback control system is, for example, a transient that changes with the overall time constant τ of the corresponding feedback control system, as shown by a thick line in FIG. As a dynamic response (hereinafter referred to as “observed value V”).

Such an observed value V is, for example, a physical quantity to be calculated for the first time for the corresponding GPS satellite (hereinafter referred to as “initial observed value V1”), the convergence value V0 of the transient response, the time series t and the time constant described above. τ can be approximated (or expressed) by an exponential function V (t) expressed by the following equation.
V (t) = V1 · exp (−t / τ) + V0 (a)

  As shown in FIG. 3, the signal processing unit 13 has observed values (= V (t1), V (t2), and V (t3)) at three time points (= t1, t2, and t3) that are different in order of the time series t. (Step S1, FIG. 2, (1), (2), (3) in FIG. 2), the following processing is performed.

(1) Processing for obtaining observation values (= V (t4) to V (tn) (≈V0)) at time points (= t4 to tn) subsequent to the above three time points (= t1, t2, t3) The “convergence value acquisition process” is omitted (step S2 in FIG. 2).

(2) The above formula (a) is constructed by substituting these time points (= t1, t2, t3) and observed values (= V (t1), V (t2), V (t3)). As a solution of the following simultaneous equations, a convergence value V0 is obtained (step S3 in FIG. 2, FIG. 3 (4)).
V (t1) = V1 · exp (−t1 / τ) + V0
V (t2) = V1 · exp (−t2 / τ) + V0
V (t3) = V1 · exp (−t3 / τ) + V0

(3) As shown by the thick straight line in FIG. 3, by applying the convergence value V0 in place of the observed value V (tn) obtained by the previously described “convergence value acquisition process”, the “positioning process” is performed. This is performed (step S4 in FIG. 2).

  That is, the convergence value V0 can be obtained with high accuracy and high speed despite the reduction in the time and processing amount required for the “convergence value acquisition process” described above.

As described above, according to the present embodiment, not only at the time of start-up, but also when the number of GPS satellites to be applied for positioning increases, the responsiveness and accuracy of positioning processing are maintained high.
Therefore, the GPS receiver according to the present embodiment includes a point where a radio signal propagation path between GPS satellites is obstructed or interrupted by features (high-rise buildings, etc.) or terrain, and the interior of the building. In addition, positioning immediately after moving from the underground passage to the outside is realized at a much higher speed and accuracy than the conventional example.

In addition, since the processing performed as described above (steps S1 to S4 in FIG. 2) requires significantly less processing than the “convergence value acquisition processing”, the surplus processing amount of the signal processing unit 13 is utilized. A reliable realization is possible.
Therefore, according to the present embodiment, it is possible to flexibly adapt to various fields and needs using existing navigation satellites such as GPS.

  In the present embodiment, the simultaneous equations described above are equal to the total number “3” of unknowns V1, τ, and V0 (= t1, t2, t3) and observed values (= V (t1), V (t2). , V (t3)) is obtained by substituting into the above equation (a).

However, the calculation for obtaining the convergence value v0 may be replaced by the following calculation, for example.
(1) The above simultaneous equations are replaced by “multiple sets of simultaneous equations obtained by substituting observed values obtained for four or more time points into the above equation (a)”.
(2) After the individual solutions of these multiple sets of simultaneous equations are obtained, the convergence v0 included in the most probable solution based on the desired criterion is applied to the “positioning process”. Adopted as power convergence value. Note that such “most likely solution” may be specified based on, for example, the least square method.

  Furthermore, in the present embodiment, the above-described equation (a) is given on the assumption that the observed value V is approximated (represented) by the exponential function V (t), and is reflected in the simultaneous equations.

However, such an expression (a) can be expressed by, for example, the various types listed below if the solution of the simultaneous equations can be obtained with desired response and accuracy within the limit of the surplus processing amount of the signal processing unit 13. An expression or function may be substituted.
(1) Approximate expression obtained by expanding (converting) expression (a) into a polynomial
(2) Monotonically decreasing function or monotonically non-increasing function that can ensure the desired accuracy

  In the present embodiment, the feedback system is not limited to the above-described DLL, AFC, and PLL, and includes hardware that performs feedback control in the analog domain and / or the digital domain, It may be any of “various software that realizes updating of a physical quantity by referring to a desired physical quantity calculated (obtained) in the process in a subsequent process”.

  Furthermore, the present embodiment is not limited to GPS satellites, and can be similarly applied to various navigation satellites such as Glonas, Galileo, Compass, and the like that are being constructed and developed.

  In the present embodiment, the positions of GPS satellites and navigation satellites replacing them may be given in any coordinate system.

  Furthermore, in the present embodiment, the present invention is applied in order to improve the responsiveness while maintaining the positioning accuracy of the GPS receiver.

  However, the present invention is applicable not only to such applications and purposes but also to shortening the time required for starting and starting the GPS receiver, as listed below, for example.

(1) Warm start after valid almanac is stored in the GPS receiver, but no ephemeris is stored or the expiration date of the previously stored ephemeris expires
(2) Hot start when valid almanac and ephemeris are accumulated in the GPS receiver

In addition, the calculation target and calculation procedure of the present embodiment are not limited to those described above, and may be any as long as desired accuracy and responsiveness are achieved.
Furthermore, in the present embodiment, the above-described processing is performed independently by the signal processing unit 13.
However, in such processing, function distribution and load distribution may be achieved in any form for a plurality of processors that perform information processing and signal processing.

  Further, the present invention is not limited to the above-described embodiments, and various configurations of the embodiments are possible within the scope of the present invention, and any improvements may be made to all or some of the components.

11 Antenna 12 Radio Unit 13 Signal Processing Unit

Claims (5)

A positioning support device for finding a physical quantity related to a navigation satellite newly applied for positioning under feedback control,
A convergence value of the physical quantity is defined as a root of a simultaneous equation in which the physical quantity sequence obtained according to the navigation data arriving in time-series order from the navigation satellite is substituted into an expression indicating a transient response of the feedback control. Estimating means for estimating;
Positioning support means for applying the convergence value to the positioning. A positioning support device for finding a physical quantity related to a navigation satellite newly applied for positioning under feedback control,
As a root of a plurality of N sets of simultaneous equations in which the physical quantity sequence obtained according to the navigation data arriving in time series from the navigation satellite is substituted into an expression indicating a transient response of the feedback control, the velocity Estimating means for estimating N candidates of convergence values of the N candidates, and estimating, as the convergence value, a specific candidate having a minimum error or falling below a predetermined threshold among the N candidates;
Positioning support apparatus, comprising: positioning promotion means for applying the specific candidate to the positioning. In the positioning assistance device according to claim 1 or 2,
The physical quantity is
It is the speed of the said navigation satellite. The positioning assistance apparatus characterized by the above-mentioned. In the positioning assistance device according to claim 1 or 2,
The physical quantity is
A positioning support apparatus characterized by being a distance of the navigation satellite. The positioning support device according to any one of claims 1 to 5,
The formula is
A positioning support apparatus that approximates the transient response.