JP2001318135A - Positioning system equipped with range finding function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a range finder measuring the distance to an object without emitting radio wave. SOLUTION: The range finder comprises a first receiving antenna receiving waves directly from GPS satellites, a first GPS receiver for calculating positioning data including time, position and speed based on signals received by the first receiving antenna, a second receiving antenna receiving signals from GPS satellites reflected on a reflector, a second GPS receiver for calculating positioning data including time, position and speed based on signals received by the second receiving antenna, and an operating section for calculating the distance from the reflector based on the positioning data outputted from the first and second GPS receivers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device, and more particularly, to a method for converting signals from the same GPS satellite into separate GPS satellites.
The present invention relates to a positioning device having a distance measuring function of calculating a distance (altitude) from a reflector based on a difference in a route by receiving the signal by a receiver.

[0002]

2. Description of the Related Art FIG. 5 shows a G operating as a conventional positioning device.
An example of a PS (Global Positioning System) receiver is briefly shown. As shown in FIG. 5, a conventional GPS receiver has a G
A signal from a PS satellite is received by a receiving antenna 1, and positioning data is calculated (positioned) by a GPS receiver 2 based on the received signal. The data includes the time on the GPS Time,
Normally, earth fixed coordinates and WGS-84 (World Geodetic S
ystem-84) is positioning data including the position, speed, etc. in a coordinate system. The positioning data is an absolute position in the coordinate system or the like, and is relative to the actual surrounding environment, that is,
The relative distance relationship must be detected using another distance measuring device.

FIG. 6 schematically shows an example of a conventional distance measuring device. As shown in FIG. 6, a conventional distance measuring device emits a signal generated by a transmitter 3 of a measurer to the outside world via a transmission antenna 4 and reflects the signal on a reflection surface (reflection object) of the outside world. Then, the signal returning to the subject is received by the receiving antenna 5 of the subject, and the received signal is detected by the receiver 6,
The signal processor 7 measures the relative distance H from the reflecting surface (reflecting object) from the difference between the transmission timing time T1 [sec] and the reception timing time T2 [sec] according to the following relationship.

H = (C × Δt) / 2 H: distance [m] from reflecting surface (reflecting object) C: speed of light (≒ 3.0 × 10 ⁸ [m / s]) Δt: transmission / reception timing difference (Δt) = T2-T1 [se
c]) Therefore, in the conventional distance measuring device, only the relative distance H to the reflecting surface (reflecting object) can be obtained, and in order to obtain the absolute position and the like, no other positioning device is used. Not be.

[0005]

As described above, in the prior art, the GPS receiver only detects the absolute position in the coordinate system, and it is difficult to detect the relative distance relationship with the surrounding environment. . The distance relationship with this surrounding environment is
It is one of the important factors for an object that can actually move to know its relative relationship. In order to detect the relationship with the surrounding environment, the relative distance relationship must be detected by a distance measuring device.

On the other hand, the conventional distance measuring device can only detect a relative distance relationship with the surrounding environment. In order to know the absolute positional relationship, a positioning device using a GPS receiver or the like is separately provided. There is a need to have. As described above, each of the prior arts has advantages and disadvantages, and different systems are used together in the overall system. Therefore, the problem of matching (integration) of output data, the problem of cost increase, and the measurement shown in FIG. When a radio wave is naturally transmitted like a distance device, there are many problems such as deterioration of frequency use efficiency, isolation of each device due to radio wave leakage, and the like.

An object of the present invention is to provide a positioning device having a distance measuring function capable of obtaining original positioning data using radio waves transmitted from a GPS satellite and also obtaining a relative distance relationship with the surrounding environment. It is intended to provide.

[0008]

According to a first aspect of the present invention, a first receiving antenna for receiving a signal from a GPS satellite, and positioning including time, position, speed, and the like based on the received signal from the first receiving antenna. A first GPS receiver for calculating data, a second receiving antenna for receiving a signal reflected from a reflector of a signal from a GPS satellite, and a positioning including time, position, speed, etc. based on the received signal of the second receiving antenna A second GPS receiver for calculating data, first and second GPS
The present invention proposes a positioning device having a distance measuring function constituted by an arithmetic unit for calculating a distance from a reflector based on positioning data output from a receiver.

According to a second aspect of the present invention, in the positioning device having the positioning function according to the first aspect, the first receiving antenna measures an elevation angle θ facing the GPS satellite from the positioning data, and the second reception antenna measures the elevation angle θ. Φ = 90 ° -θ related to
The present invention proposes a positioning device having a distance measuring function configured to obtain a distance from the reflective surface by being directed to the reflective surface to be measured at an angle of. [Operation] According to the present invention, the position is measured as usual using radio waves transmitted from GPS satellites, and the same GPS is used.
The satellite radio waves are received by two receivers with a path difference,
The distance to the reflecting surface on which the path difference has occurred can be obtained by calculation based on the positioning data of the two receivers.

Therefore, according to the present invention, a distance measuring function can be added to the positioning function originally provided in the GPS receiver. Particularly, it is suitable for measuring altitude (distance in the height direction), and has an advantage that a distance measuring function can be obtained without naturally emitting radio waves.

[0011]

FIG. 1 shows an embodiment of a positioning device having a distance measuring function according to the present invention. The positioning device having the distance measuring function according to the present invention includes first and second receiving antennas R.
1, R2 and two first and second GPS receivers 2A, 2A
B and the arithmetic unit 8. First
In the example shown in FIG. 2, the receiving antenna R1 has a normal receiving characteristic, that is, the signal transmitted by the GPS satellite T is a right-handed polarized wave. ) Is used. This first receiving antenna R1
Receives a direct wave from the GPS satellite T.

On the other hand, the second receiving antenna R2 has a normal GP
An antenna having a left-handed rotational polarization receiving characteristic opposite to the first antenna R1 for receiving a signal from the S satellite is used. By using the antenna having the left-handed rotationally polarized wave reception characteristic, a radio wave whose rotational polarization characteristic reflected by the object is reversed is received. The signal of the GPS satellite is right-handed polarization, and the signal reflected odd number of times has left-handed rotation polarization characteristics. In addition, since the signal strength is degraded each time the light is reflected due to an increase in the number of times of reflection, only one reflection signal can be extracted by setting an appropriate threshold, for example. Therefore, the first GPS receiver 2A outputs position information obtained by a direct wave, and the second GPS receiver 2B generates position information by a reflected wave reflected once.

A path difference ΔL is given to a direct wave received by the first receiving antenna R1 and a single reflected wave received by the second receiving antenna R2. The arithmetic unit 8 calculates a distance H (altitude) from the path difference ΔL to, for example, the second receiving antenna R2 and the reflection surface S (see FIG. 2). Using FIG.
The method of the arithmetic processing will be described. The position of the GPS satellite is T (x ₁ , y ₁ ) Positioning data The position of the first receiving antenna R 1 is R 1 (x ₂ , y ₂ ) Positioning data The angle at which the GPS satellite T is looked up from the first receiving antenna R 1. θ Positioning data (this angle θ is equal to the angle θ when the signal of the GPS satellite T is reflected by the reflector) The difference between the position of the second receiving antenna R2 and the position of the first receiving antenna R1 is represented by (Δx, Δy ) ... known data The point at which the signal of the GPS satellite T is reflected by the reflecting surface is represented by S and the line segment T.
Let D be the intersection of a line segment perpendicular to -R1 and line segment TS, and let H [m] be the distance from the reflective surface.

Further, since the GPS satellite T is sufficiently far from the receiving point, the line segment TR1 and the line segment TDS can be regarded as parallel line segments. Therefore, the path difference Δ Δ between the receiving points
L is DSR2. This path difference ΔL is equal to each GP
ΔL = | PR1−PR2 | PR1: Pseudorange of GPS receiver 2A ... Positioning data PR2: Pseudo GPS receiver 2B Distance ... Obtained as positioning data. By obtaining the path difference ΔL, the distance H from the reflecting surface to the second receiving antenna R2 becomes

[0015]

(Equation 1)

Thus, the relative distance (altitude) H from the reflecting surface can be measured only by the combination of the GPS receiver.
The process of deriving the expression (A) will be described below. Condition: Line segment T-R1 and TDS are parallel. Satellite T
Are the coordinates x ₁ and y ₁ , and the coordinates of the first receiving antenna R1 are x
_2, when the y _2, line T-R1 is expressed by the following equation.

[0017]

(Equation 2)

Since the line segments T-R1 and T-D are equal, the path difference ΔL between the receiving points R1 and R2 is DSR2. Further, when the line segment R2-S is extended and the intersection point with the line segment perpendicular to the reflecting surface from the point D is defined as Q, the path difference ΔL (DSR)
Are equal in length of the line segment R2-SQ. Therefore, the coordinates of the point Q can be expressed as follows. Q _x = x ₂ + Δx + ΔL cos θ (3) Q _y = y ₂ −Δy−ΔL sin θ (4) Therefore, the intersection of the line segment R1-D (equation 2) and the line segment DQ (equation 3) Is

[0019]

(Equation 3)

[0020]

(Equation 4) Therefore, the height H from the reflecting surface is

[0021]

(Equation 5)

Equation (A) is derived. Next, a method in which the first receiving antenna R1 receives a direct wave and the second receiving antenna R2 receives a reflected wave once will be described. In general, a signal arriving at a receiving antenna is a signal obtained by combining a direct wave and a reflected wave reflected on an object or the like. The autocorrelation characteristic of this combined signal (the receiving side demodulates by taking the autocorrelation on the receiving side since the GPS uses a spread communication system)
Due to the influence of the polarization plane characteristics and the spatial propagation distance, the signal accuracy deteriorates, the bit error and the like cause the correlation value to be lower than the signal arriving first. Therefore, in the configuration of the present invention, a direct wave + an even number of reflected waves (FIG. 3A) is applied to the GPS receiver 2A and an odd number of reflected waves (FIG. 3B) is applied to the GPS receiver 2B from the polarization characteristics of the antenna. ) Will be detected.

As shown in FIG. 3, each GPS receiver 2A,
By setting appropriate thresholds SH1 and SH2 in 2B, the GPS receiver 2A can detect only a direct wave, and the GPS receiver 2B can detect only a single reflected wave. Reflected waves,
Noise can be separated. Further, by synchronizing with the detected correlation interval, it is possible to reduce the influence of unnecessary signals.

Regarding the positioning timing chart of the pseudo distances PR1 and PR2, as can be understood from the above description,
In the first GPS receiver 2A, the propagation delay time of the direct wave is
Also, the second GPS receiver 2B measures the propagation delay time of the signal that has been reflected once and arrived. In FIG.
4 shows a positioning timing chart of the S receivers 2A and 2B.
As can be seen from FIG. 4, the measurement after the synchronization of the GPS positioning conditions can be performed 1000 times for 1 second, which is a normal GPS positioning interval, and by averaging these data. Accuracy can also be improved. Also, the update rate can be sufficiently supported.

[0025]

As described above, according to the present invention, in addition to the ordinary GPS positioning system, a configuration in which the GPS receiving system using the second receiving antenna R2 for left-handed rotational polarization and the arithmetic unit 8 are added. By using the conventional GPS
It is possible to measure the distance from the reflector, which could not be measured by the receiver alone. Furthermore, in the present invention, the measurement results between the GPS receivers are input to the calculation unit 8, so that the compatibility of data is maintained, whereby the calculation unit 8 can be simplified.

Further, in the present invention, since the distance measuring function is obtained by using a GPS receiver which can be obtained at a relatively low price, there is obtained an advantage that it can be manufactured at a lower cost as compared with a conventionally used radio emission type radio altimeter. Can be Further, according to the present invention, since the radio wave is not naturally emitted, there is obtained an advantage that the frequency use efficiency can be improved. Further, when the positioning device having the distance measuring function according to the present invention is mounted on an aircraft, for example, as an altimeter, since it does not emit radio waves, it does not interfere with other devices and can be easily incorporated. In particular, the radio altimeter that measures altitude has a large transmission power, so it has a large interference with other devices, and its countermeasures are costly.However, this invention can be mounted on an aircraft at a low cost in this regard. is there.

Further, according to the present invention, each GPS receiver 2
By taking the difference ΔL between the pseudo-ranges PR1 and PR2 of A and 2B, a GPS-specific SA (Selective Ava
Error components due to ilability), tropospheric delay, ionospheric delay, etc., are almost negligible, providing the advantage of being able to measure accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an embodiment of the present invention.

FIG. 2 is a diagram for explaining a distance measuring function of the positioning device according to the present invention.

FIG. 3 is a timing chart for explaining the operation of the present invention.

FIG. 4 is a timing chart for explaining the operation of the present invention as in FIG. 3;

FIG. 5 is a block diagram for explaining a conventional technique.

FIG. 6 is a block diagram for explaining another example of the related art.

[Explanation of symbols]

 R1 First receiving antenna R2 Second receiving antenna 2A, 2B GPS receiver 8 Operation unit T GPS satellite

Claims (2)

[Claims] 1. A. First Embodiment A. A first receiving antenna for receiving signals from GPS satellites; B. a first GPS receiver that calculates positioning data including time, position, speed, and the like based on the reception signal of the first reception antenna; B. a second receiving antenna for receiving a signal reflected from a reflector of the signal from the GPS satellite; B. a second GPS receiver that calculates positioning data including time, position, speed, and the like based on the reception signal of the second reception antenna; A positioning device having a distance measurement function, comprising: a calculation unit that calculates a distance from a reflector based on positioning data output from the first and second GPS receivers. 2. The positioning device according to claim 1, wherein said first receiving antenna measures an elevation angle θ of said GPS satellite from positioning data, and said second reception antenna measures an elevation angle θ of said GPS satellite. A positioning device provided with a distance measuring function, which is directed to a reflection surface to be measured at an angle of φ = 90 ° −θ and calculates a distance from the reflection surface.