JP2001272452A - Method for measuring position during loss of satellite radio wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position measuring method for a mobile station during the loss of a satellite radio wave (when there are less than three supplementary satellites). SOLUTION: By this position measuring method, the position (XB, YB) of the mobile station is found by a regular analysis expression which is used when carrier waves can be received from four satellites while the elliptic body height of the mobile station is made constant. The position (XA, YA, ZA) of a base station in an earth coordinate system is already known, a pseudo-noise code signal of an L1 band (1575.42 MHz) or an L2 band (1227.6 MHz) from an artificial satellite is received by a GPS receiving antenna and decoded by the GPS receiver, and its corrected data are sent to the mobile station through a corrected data transmitter and a transmitting antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a position of a mobile station, and more particularly to a method for measuring a position when a satellite wave is lost.

[0002]

2. Description of the Related Art Conventionally, GPS (Global Position) using an artificial satellite has been used as a method for measuring the position of a mobile station.
ing System) is known. This GPS
The center frequencies subjected to the spread spectrum processing using the pseudo noise code signals from a plurality of satellites respectively have L1 band (1575.42 [MHz]) and L2 band (1227.6).
[MHz]), the mobile station side and the base station simultaneously receive the ranging signals (orbit information and clock information, etc.) of the four satellites, and the phase of the carrier wave is transmitted. There is a method of measuring the position of the mobile station with high accuracy (several tens of cm or less) by comparing and measuring data.

[0003]

As described above, in order to accurately measure the position of the mobile station, it is well known that the position coordinates (XB, XB, ZB) of the mobile station and the time t are used.
Are unknowns. Therefore, in order to solve them, it is necessary to receive ranging signals of at least four satellites. However, a mobile station cannot always receive ranging signals from four satellites due to an obstruction in the sky. 3
If the number of mobile stations becomes less than the number, there arises a problem which cannot be dealt with by the conventional method of measuring a mobile station. Therefore, the present invention provides a calculation method that enables accurate position measurement even in such a case.

[0004]

According to the position measuring method of the present invention, the ellipsoidal height (h) of the mobile station is made constant in a normal analysis formula used when a carrier wave from four satellites can be received. Is what you want. More specifically, first, in (Equation 1), ZB is obtained from the position (XB, YB) of the mobile station, and in (Equation 2), the correction amounts ΔX and ΔY are close to “0” (permissible). XB and YB at (within error) are the positions of the mobile station to be obtained. or,
According to the position measuring method of the present invention, when the elevation angles (θ1, θ2) with respect to the two satellites are equal (Equation 5), when the azimuth measuring device provided in the mobile station measures the azimuth, the traveling direction linear expression ( By solving equation (6), the position of the mobile station (X
B, YB).

[0005]

FIG. 1 is a conceptual diagram of the present invention.
The relation between the four artificial satellites, the base station and the mobile station is shown. The base station and the mobile station receive simultaneously from a plurality of satellites, and transmit the phase data of the carrier as correction information and phase information to the mobile station. The mobile station measures the position with high accuracy based on the data. That is, the position of the base station in the earth coordinate system (XA, YA, ZA) is known, and the L1 band (1575.42 [MHz]) or the L2 band (12
27.6 [MHz]) is received by a GPS receiving antenna, and GPS (Global Position) is received.
(Ioning System) The decoding is performed by the receiver, and the correction data is transmitted to the mobile station via the correction data transmitter and the transmission antenna. Also, the position of the mobile station is determined by DGPS with the base station.
(Differential Global Posi
The mobile station is provided with a GPS receiver and a correction data receiving antenna for receiving correction data from the base station, and a correction data receiver for measuring by the Tying System.

The position coordinates of the mobile station are (XB, YB, Z
B) and the coordinates of the first satellite that can be supplemented (X1, Y1,
Z1), coordinates of the second satellite (X2, Y2, Z2), coordinates of the third satellite (X3, Y3, Z3), coordinates of the fourth satellite (X4,
Y4, Z4). Also, as is well known, the position coordinates (XB, YB, ZB) of the mobile station are obtained by using a pseudo noise code signal (C / A, P code, etc.) and carrier phase data.
To obtain the four unknowns of the clock error Δt
It is necessary to solve a normal analysis formula based on the position coordinates of the satellites No. to No. 4, and this normal analysis formula is well known and will not be described.

Next, a description will be given of a measuring method at the time of a lost search in which the carrier of one of the four satellites (the fourth satellite) cannot be received. In this case, the number of unknowns in the normal analysis formula (not shown) is four (XB, Y
In spite of B, ZB, time t), only the carrier waves from three satellites can be received, so that the normal analysis formula cannot be solved. Therefore, assuming that the ellipsoidal height (h) of the mobile station, which is estimated to have the least change in the mobile station, is constant, the WGS84 rectangular coordinate system is represented by (Equation 1).

[0008]

(Equation 1) Here, m: radius of curvature of the wattle line, a: radius of the equator, e: eccentricity, φ: latitude f: oblateness, b: polar radius, h: ellipsoidal height XB: mobile station coordinates, YB: mobile station coordinates Coordinates, ZB: Coordinates of the mobile station.

Next, the relationship between the distances, coordinates and phases between the three satellites and the base station and mobile station is given by (Equation 2).

(Equation 2)

Here, f: frequency of the L1 band from the artificial satellite (1575.42 [MHz]) c: light speed (299792458 m / s) (X1, Y1, Z1): coordinates of the first satellite (X2, Y2, Z2): coordinates of the second satellite (X3, Y3, Z3): coordinates of the third satellite (XB, YB, ZB): position coordinates of the mobile station (XA, YA, ZA): position of the base station The coordinates ΔX and ΔY are correction amounts.

.Phi.12AB and .phi.13AB are double phase differences obtained from the phase data of the first and second satellites measured at the base station and the mobile station, and are obtained from (Equation 3).

(Equation 3) Here, φ1A: phase data of the first satellite received by the base station φ2A: phase data of the second satellite received by the base station φ3A: phase data of the third satellite received by the base station φ1B: phase data received by the mobile station Phase data of one satellite φ2B: Phase data of second satellite received by mobile station φ3B: Phase data of third satellite received by mobile station

Further, N12 and N13 are phase angularity (integer value bias), and the position (X
(B, YB, ZB) is obtained by (Equation 4) at the time when it is known.

(Equation 4)

In the above (Equation 1) to (Equation 4), the mobile station position (XB, YB, ZB) at a known point in time is set as an initial value, and the mobile stations whose correction amounts ΔX, ΔY become “0” are set. Position (X
B, YB, ZB). Note that the position (ZB) of the mobile station is obtained by (Equation 1). Many methods are known for obtaining an equation in which the correction amounts ΔX and ΔY are “0”. In this example, however, a sequential substitution method is employed, and the method does not diverge, and is simply performed by several repeated calculations. I was able to ask. That is, XBi, YBi, and ZBi obtained from Expression 1 are used as initial values, and the correction amounts ΔXi and ΔYi are obtained from Expressions (1) to (Equation 4). Until the position (XB, YB, ZB) is changed to (XBi + ΔXi, YB
i + ΔYi), and repeat the above (Equation 2) to (Equation 4) to calculate.

The values (XBi, YBi, ZBi) when the correction amounts .DELTA.Xi, .DELTA.Yi become equal to or less than an allowable value close to "0" are the positions of the mobile station. As described above, in a state where only three satellites can receive, the ellipsoidal height (h) where the position of the mobile station has the least change is assumed to be constant, but the calculation method is simple and short. And the measurement accuracy is several tens cm or less, which is sufficient for practical use.

Next, a description will be given of a measurement method at the time of a lost search in which only carrier waves from two satellites can be received. In this case, as shown in FIG.
Since the satellites are located far away, assuming that the elevation angle (θ1) of the base station and the mobile station with respect to the first satellite and the elevation angle (θ2) of the second satellite are equal, the difference between the phase data received by the base station and the phase data received by the mobile station is assumed. Is the path difference. Then, considering two satellites capable of receiving the path difference, a straight line equation in which the mobile station exists can be expressed by (Equation 5). This (Equation 5) is an equation in which the altitude difference between the base station and the mobile station is corrected.

[0016]

(Equation 5)

(X1, Y1): coordinates of the first satellite, (X2,
Y2): Coordinate of the second satellite φ1AB: Single phase difference between the first satellite, the base station and the first satellite, and the mobile station φ2AB: Single phase difference between the second satellite, the base station and the second satellite, and the mobile station λ: Wavelength φ12AB: Double phase difference between first and second satellites, base station, and mobile station θ1: Elevation angle from base station to first satellite θ2: Elevation angle from base station to second satellite Δh: Altitude difference between base station and mobile station

FIG. 3 shows the concept of the above (Equation 5). For the first satellite, the base station determines the intersection (straight line U) of the K1 plane (perpendicular to the first satellite) and the tangent plane E (horizontal plane).
1) The mobile station is located at the intersection (straight line D1) between the K1 plane and the tangent plane E (horizontal plane) in consideration of the path difference with respect to the tangent plane E (horizontal plane). Also, for the second satellite, the base station is K2
At the intersection (straight line U2) between the plane (perpendicular to the second satellite) and the tangent plane E (horizontal plane), the mobile station considers the path difference to the tangent plane E (horizontal plane) and the K2 plane and the tangent plane E (horizontal plane). )
At the intersection (straight line D2). Therefore, (Equation 5)
Is the intersection (P) of the straight line U1 and the straight line D2 and the straight line U
2 and a straight line connecting the intersection (Q) of the straight line D1.

The mobile station is provided with an azimuth measuring device for measuring the traveling directions of X and Y, and the azimuth (α)
The linear equation based on (m = tan (α)) is Y−YB = m (X
-XB) (Equation 6). By solving Equations (5) and (6), the position (XB,
YB) can be obtained. As described above, in a state where only two satellites can receive, the position of the mobile station can be easily obtained by assuming that the elevation angles with respect to each satellite are equal, and the measurement accuracy is several tens cm. The following is sufficient and can be practically used.

[0020]

According to the position measuring method of the first aspect, even when the carrier waves from three satellites can be received, the ellipsoidal height (h) of the mobile station is determined to be constant, so that the number can be easily calculated. The position of the mobile station can be measured with an accuracy of 10 cm or less. In addition, the position measuring method according to the second aspect assumes that the elevation angles with respect to the two satellites are the same, so that even when only two satellites can be received, the position measurement method can be easily performed by the following equation.
The position of the mobile station can be measured with an accuracy of less than cm.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a satellite, a base station, and a mobile station.

FIG. 2 is a diagram illustrating elevation angles of a base station and a mobile station with respect to two satellites.

FIG. 3 is a diagram showing positions where base stations and mobile stations exist for two satellites.

[Explanation of symbols]

 (XB, YB, ZB) Position coordinates of mobile station (XA, YA, ZA) Position coordinates of base station (X1, Y1, Z1) Coordinates of first satellite (X2, Y2, Z2) Coordinates of second satellite (X3, Y3, Z3) coordinates of the third satellite (X4, Y4, Z4) coordinates of the fourth satellite

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiromi Okada 1 at 60, Kutsubo, Iwazuka-cho, Nakamura-ku, Nagoya-shi Within Nakanishi Engineering Co., Ltd. (72) Inventor Tadashi Hashimoto 7992 Inaucho, Suzuka-shi, Mie Co., Ltd. Inside Suzuka Circuit Land (72) Inventor Yoshio Uchida 7792 Inamachi, Suzuka City, Mie Prefecture F-term in Suzuka Circuit Land Co., Ltd.

Claims (2)

[Claims] A reference position is calculated at specific time intervals by position correction between a base station and a mobile station using DGPS, and
When a carrier wave from three satellites can be received in the normal analysis formula used when a carrier wave from three satellites can be received, the ellipsoidal height (h) of the mobile station is set constant in the normal analysis formula. And a position (XB, YB). 2. A reference position is calculated at specific time intervals by position correction between a base station and a mobile station using DGPS, and
When a carrier wave from two satellites can be received in the normal analysis formula used when a carrier wave from two satellites can be received, the following equation assumes that the elevation angles with respect to each satellite are equal in the normal analysis formula. , The position of the mobile station (X
B, YB).