JPH0666917A - Gps location system - Google Patents

Abstract

PURPOSE:To establish a system, which is hard to be affected by the selection availability function of an actually operating satellite by storing the error in position measurement and updating the error in position measurement at every time when the passing position of a vehicle is obtained. CONSTITUTION:A correcting means 102 is constituted of a GPS measured-position introducing means 1, a measured-position-error introducing means 2, a measured-position-error memory means 3 and a measured-position correcting means 4. The measured-position-error introducing means 2 obtains the error at a receiving point based on the measurement of the receiving point and the difference between the measured position of the receiving point and the passing position of a vehicle obtained with a beacons 200 provided on a road at a constant interval. The measured-position-error memory means 3 stores the error in measured position and updates the error of the measured position at every time the passing position of the vehicle is obtained. The measured-position correcting means 4 performs the correction with the error of the measured position of the receiving point, and the corrected measured position is displayed on a display device 300. In the measured-position-error introducing means 2, the measured position of the receiving point and the specified position on a map displayed on the display device 300 are established when the vehicle has passed. The error of the measured position can be obtained based on the difference from the passing position of the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS (Global Positioning System) using a satellite whose coverage is on the whole earth. In particular, the present invention corrects positioning deteriorated by intentional deterioration of accuracy on the satellite side. To improve the positioning accuracy G
Related to PS Location System.

[0002]

2. Description of the Related Art GPS is a worldwide radio wave positioning system using artificial satellites, which is planned and implemented by the US Department of Defense, and finally 24 including three spare satellites.
Four satellites will be launched into each of the six orbital planes. Some of these satellites belong to "Block I" and some belong to "Block II", and 18 satellites are currently in operation. The satellites belonging to "block I" are used for testing, and the satellites belonging to "block II" are used for actual operation. By receiving radio waves from four of these satellites, it becomes possible to perform three-dimensional positioning (longitude, latitude, altitude) of the receiving point. However, two-dimensional positioning of the receiving point is possible by receiving radio waves from three satellites. In the case of three-dimensional positioning, the receiver adopts four systems and receives four satellite radio waves by multi-channel or high-speed switching. Further, positioning calculation can be performed by capturing four or more satellites and always selecting a satellite combination from which a positioning error is the smallest.

By the way, a satellite for actual operation belonging to "Burok II" has a function called Select Availability (SA) that can control positioning accuracy when using GPS.
This function can be used intentionally to detect the satellite synchronization clock and degrade the positioning accuracy of the receiver. The test satellite belonging to "Block I" does not have such a function.

[0004]

However, three-dimensional positioning requires reception of radio waves from at least four satellites,
At present, there is no choice but to use the satellite radio waves including the actual operation satellite, so that if the actual operation satellite fulfills the SA function, the reception accuracy is deteriorated by 100 m to 200 m.

Therefore, in view of the above problems, it is an object of the present invention to provide a GPS location system which is less likely to be affected by the select reliability function of the actual operation satellite of "Block II".

[0006]

In order to solve the above problems, the present invention provides a GPS location system that receives signals from a plurality of satellites to obtain the positioning of a reception point, a positioning error deriving means, and a positioning error storage. Means and positioning correction means are provided. The positioning error deriving unit derives the positioning error of the receiving point from the difference between the positioning of the receiving point and the passing position of the vehicle obtained by the beacons installed at regular intervals on the road.

The positioning error storage means stores the positioning error and updates the positioning error each time the passing position of the vehicle is obtained. The positioning correction means corrects the positioning of the reception point by the positioning error and causes the display to display the corrected positioning. The positioning error deriving means determines the positioning of the receiving point and the positioning error of the receiving point based on the difference between the position of the vehicle and a predetermined position on the map displayed on the display when the vehicle passes through the position. It may be derived.

[0008]

According to the GPS location system of the present invention, the reception is obtained from the difference between the positioning of the receiving point by the positioning error deriving means and the passing position of the vehicle obtained by the beacons installed on the road at regular intervals. The positioning error is derived, the positioning error is stored in the positioning error storage unit, and the positioning error is updated within a period of 1 to 2 hours each time the passing position of the vehicle is obtained. The positioning of the receiving point is corrected by the error of the positioning by the means, and the corrected positioning is displayed on the display. Therefore, the accuracy can be improved even at the time of SA.

The positioning error deriving means determines the positioning of the receiving point and the positioning error of the receiving point based on the difference between the positioning of the receiving point and the passing position of the vehicle. Similarly, the accuracy for actual operation can be improved by deriving.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a GPS location system according to a first embodiment of the present invention. Note that, throughout the drawings, the same reference numerals or symbols are used to represent the same components. In the positioning accuracy control by Select Availability (SA) of the satellite for actual operation belonging to "Block II", the positioning accuracy of the receiver is deteriorated by intentionally detecting the synchronous clock in a cycle of about 1 to 2 hours, and the error is systematic. It is known that the error is. Focusing on this control cycle (about 1 to 2 hours), the GPS location system shown in this figure performs positioning by performing the demodulation processing of the antenna 100 that receives radio waves from the satellite and the radio waves received by the antenna 100. GPS receiver 101 to be derived and the GP
A positioning correction means 102 for correcting the positioning with data from a beacon receiver described later in the S receiver 101, and a spot communication road device for providing position information, road information, etc. An in-vehicle antenna 201 that receives radio waves from a beacon 200 installed every ~ 5 km, and demodulates the received radio waves of the antenna 201 to derive the position of the passing point, and the position data of the passing point. A beacon receiver 202 for transmitting the position to the positioning correction means 102, and a display 300 for displaying the positioning corrected by the positioning correction means 102.

The beacon 200 is used for RACS (Road-to-Vehicle Information System).
It may be used for S (new car traffic information and communication system), and is a VIC that integrates RACS and AMTICS.
The one used for S may be used. In these road-to-vehicle information systems, etc., errors are accumulated in dead reckoning using a sensor and a map matching type location device using a map. There is. This beacon 100
Are installed every 2 to 5 km, it is possible to provide position information (x0, y0, z0) to the GPS location system mounted on the vehicle within the control cycle (about 1 to 2 hours).

FIG. 2 is a diagram showing the configuration of the GPS receiver shown in FIG. In the GPS receiver 101 shown in the figure, the antenna 100 receives a transmission signal modulated by a C / A code from a plurality of artificial satellites. In this transmission signal, 1575.
The 42 MHz carrier is phase-modulated by a digital code called C / A code. The C / A code is called a pseudo noise code (PN), and there are 36 types of patterns. Different C / A codes are assigned to each satellite, which is known to the user. The above-mentioned phase modulation is called spread spectrum modulation, and each satellite can be identified even with the same frequency. Further, data required for positioning called "navigation message" is superimposed on the C / A code. This navigation message includes orbit information of each satellite, correction values of atomic clocks mounted on the satellites, propagation delay correction coefficient by the ionosphere, general information of all satellites, and the like. At the US Department of Defense ground station,
In addition to operation management to maintain accurate orbits with a satellite accurate orbital element measurement system, daily corrections such as time bases, orbital elements, position correction parameters, etc. are performed to maintain GPS functions, and quality control is performed. It is carried out.

Returning to FIG. 1, the preamplifier 103 connected to the antenna 1 is built in the antenna 1. An RF amplifier 104 connected to the preamplifier 103 amplifies an RF signal received from the GPS receiver 101. The oscillator 105 is a temperature-compensated crystal oscillator. A PLL (Phase Locked Loop) 106 connected to the oscillator forms a signal for local oscillation using the oscillator 105 as a reference signal. The mixer 107 connected to the RF amplifier 104 mixes the RF signal of 1575.42 MHz from the RF amplifier 104 with a local oscillation signal and frequency-converts it to an intermediate frequency (IF signal) of 4.092 MHz. The mixer 107
The intermediate frequency filter amplifier 108 connected to
The signal converted at 07 is amplified by about 110 dB. An A / D converter (Analog to Digital Converter) 109 connected to the intermediate frequency filter amplifier 108 converts the analog signal amplified by the A / D converter 9 into a 1-bit digital signal, and a DSP (Digital Signal Processor) ) 11
Output to 0. In the DSP 110, the A / D converter 1
When a digital signal is input from 09, the frequency is adjusted to the satellite radio wave, and at the same time, the C / A code corresponding to each satellite is generated and the phase of the C / A code is adjusted to despread the spectrum and demodulate the data. The DSP 11
The data demodulated by 0 is the central processing unit 111,
ROM (Read Only Memory) 112, RAM (Random Acces
s Memory) 113, a microcomputer including an I / O interface 114 and the like derives and corrects positioning. The I / O interface 114 inputs the position data from the beacon receiver 202, and displays the corrected positioning on the display 300.

FIG. 3 is a diagram showing the configuration of the positioning correction means shown in FIG. The positioning correction means 102 shown in the figure includes a GPS positioning deriving means 1 which is formed in the microcomputer and derives the positioning from the navigation message. The GPS
The positioning derivation means 1 obtains a pseudo distance RP including an error with respect to the true distance between the satellite and the receiving point. This pseudo distance R
As for P, the C / A code is sent at the timing exactly synchronized with the atomic clock mounted on each satellite.
It is derived from the phase shift amount of the / A code. Furthermore, the satellite and the receiving position are represented by three-dimensional coordinates from the orbit information of each satellite, the correction value of the atomic clock mounted on the satellite, the correction coefficient of the propagation delay due to the ionosphere, and the orbit information of all satellites. Here, x, y, and z are coordinates of a receiving point, u, v, and w are coordinates of satellites, and pseudo distances RPi, coordinates ui, vi, and wi (i = 1,2,3) for each of four satellites. , 4), the following equation holds.

RPi = [(ui −x) ² + (vi −y) ²
+ (Wi-z) ² ] ^1/2 + CΔtr where C represents high speed and Δtr represents the difference between the GPS reference time and the reception time. The satellite positions ui, vi, wi can be obtained by solving the Kepler equation from the orbital parameters in the navigation message. Therefore, the receiving points x, y, and z can be obtained by solving the above equation.

From the GPS positioning derivation means 1, the receiving point x,
The positioning error deriving means 2 which has obtained the y and z data derives the positioning error as follows when the position x0, y0 and z0 data position data from the beacon receiver 202 is present. Δx = x−x0 Δy = y−y0 Δz = z−z0 Positioning errors Δx, Δy, Δ from the positioning error deriving means 2
The positioning error storage means 3 for storing z is the positioning error deriving means 2
The positioning error stored in the latest positioning error obtained in step 1 is updated.

From the GPS positioning derivation means 1, the receiving point x,
The positioning correction means 4 that has obtained the y and z data reads out the positioning error from the positioning error storage means 3 each time it receives the reception point data, and corrects it as follows. x = x−Δx y = y−Δy z = z−Δz The positioning data thus obtained is displayed on the display device 300.

According to this embodiment, the accuracy can be improved even when the actual operation satellite belonging to the "block II" which detects the synchronous clock at a constant cycle and deteriorates the positioning accuracy is used. FIG. 4 shows a GP according to a second embodiment of the present invention.
It is a figure which shows an S location system. G shown in this figure
In the PS location system, instead of the beacon receiver 202 of the first embodiment shown in FIG. 1, the map display control means 301 for providing map data to the display 300 is the GP display control means 301.
The position information (x
0, y0, z0). The map display control means 3
The map data storage means 302 formed of a CDROM for providing map data to 01 has a positioning error correction point database. This positioning error correction point is the display 3
00, and provides location information to correct the GPS positioning. Intersections, stations, etc. are selected as the points to be corrected. The operation key 303 for giving an instruction to the map display control means 301, when the vehicle passes through the positioning correction error correction point displayed on the display device 300, if a predetermined key is pressed, the position information is sent to the positioning correction means 102. (X
0, y0, z0) are provided. The key operation is performed manually.

FIG. 5 is a flow chart for explaining a series of operations of the second embodiment. In step 1 shown in the figure, GPS positioning processing is performed by the GPS positioning deriving means 1,
Positioning x, y, z by GPS is obtained. In step 2, the correction point is displayed on the map of the display 300 while the vehicle is traveling, and when the correction point is passed, the operation key 3
It is determined whether 03 is pressed.

In step 3, when the operation key 303 is pressed while passing through the correction point, the position information (x0, y0, z0) of the correction point is fixed, and the positioning error deriving means 2 calculates the error = positioning-corrected position. As a result, Δx, Δy, and Δz can be obtained. This error is obtained each time the operation key 303 is pressed at the correction point, and is stored and updated in the positioning error storage means 3.

In step 4, the positioning correction means 4 obtains the new position as new position = positioning−error, and step 5
Then, this result is displayed on the display 300, and if there is a positioning request in step 6, the process returns to step 1 and the above procedure is repeated. According to this embodiment, the same effect as that of the first embodiment can be obtained.

[0022]

As described above, according to the present invention, the positioning of the receiving point can be determined from the difference between the positioning of the receiving point and the passing position of the vehicle obtained by the beacons installed at regular intervals on the road. An error is derived, the positioning error is stored, and the positioning error is updated every time a vehicle passing position is obtained. The positioning error is corrected within a period of 1 to 2 hours, and the positioning of the receiving point is corrected by the positioning error. Since it is displayed on the display, the accuracy can be improved even when the satellite for actual operation belonging to “Block II” that deteriorates the positioning accuracy by detecting the synchronous clock at a constant cycle is used.

[Brief description of drawings]

FIG. 1 is a diagram showing a GPS location system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a receiver shown in FIG.

FIG. 3 is a diagram showing a configuration of a positioning correction means in FIG.

FIG. 4 is a diagram showing a GPS location system according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating a series of operations of the second embodiment.

[Explanation of symbols]

 1 ... GPS positioning derivation means 2 ... Positioning error derivation means 3 ... Positioning error storage means 4 ... Positioning correction means 101 ... GPS receiver 102 ... Positioning correction means 200 ... Beacon 202 ... Beacon receiver 300 ... Display 301 ... Map display control Means 302 ... Map data storage means 303 ... Operation keys

Claims (2)

[Claims] 1. A GPS location system for receiving signals from a plurality of satellites to measure the position of a receiving point, the vehicle being obtained by the positioning of the receiving point and beacons installed at regular intervals on a road. Positioning error deriving means (2) for deriving the positioning error of the receiving point from the difference with the passing position of
And a positioning error storage means (3) for storing the positioning error and updating the positioning error each time the passing position of the vehicle is obtained.
And a positioning correction means (4) for correcting the positioning of the reception point with the positioning error and displaying the corrected positioning. 2. The positioning error deriving means (2) determines the position of the receiving point and is determined when the vehicle passes a predetermined position on the displayed map, and the receiving point is determined from the difference between the passing position of the vehicle. The GPS location system according to claim 1, which derives an error in positioning of the.