JPS6340878A - Gps position measuring instrument - Google Patents

Abstract

PURPOSE:To prevent errors and increase accuracy of position measuring calculation by comparing a rectilinear range to a satellite measured on the basis of a satellite radio wave and that obtained by dead reckoning with each other and, when a difference between both is larger than a prescribed value, stopping a position calculation. CONSTITUTION:Satellite radio waves received by an antenna 1 are amplified, detected and inputted to a CPU 15 via a data detecting filter 14. Thus, the three-dimensional position of an object whose position is to be measured on terrestrial coordinates is measured. On the other hand, a dead reckoning instrument 25 connected to a bearing sensor and a vehicle speed sensor detects the quantity of vehicle movement in a vector value and the predicted value of the quantity of the movement of synchronous timing between before and after the movement is obtained by a synchronism monitor 24. When synchronism is impossible or there is a large difference between the quantity of movement calculated from the output of a voltage controlled oscillator 9, the CPU 15 stops a position calculation whereby the error of the calculation is prevented and an accuracy in a position measurement is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is based on GPS (Global Pos.
itionin.

3 system).

[Prior art] A GPS positioning device receives radio waves from an artificial WI star for multiple satellites necessary for positioning.
It measures the position of aircraft, ships, vehicles, and other objects to be positioned, and its principles and methods are described in Japanese Patent Application Laid-Open No. 60-1
5573, Electronic Communication (Technical Research Report of the Society of Engineering VOI, 84.
ff1.78.5ANE84-12. Automotive technology 198
5. Vol, 39-1 (Satellite Navigation Global Positioning System), Voyage No. 62 NAVSTAR/G
Familiar with PS (Worldwide Positioning System), etc.

However, since these conventional GPS position measurements are based on receiving waves directly from satellites, if the receiver receives interference waves such as reflected waves from a building fence, However, there was a problem in that the position of the object to be measured was incorrectly determined.

[Object of the invention] This invention improves the above problems and provides a GP that does not perform incorrect positioning even if the receiver receives interference waves.
The purpose of this invention is to provide an S position measurement neck device.

[Summary of the Invention] In order to achieve the above object, the present invention includes a GPS position measuring device that includes a heavy-duty capture means that captures satellite radio waves, and a positioning device that detects a positioning object based on satellite data such as the straight-line distance from the captured satellite. a position calculation means for calculating a position; a straight-line distance calculation means for determining the straight-line distance between the object to be measured and a predetermined satellite as a tri'i4 value by knowing the current position of the object to be measured by dead reckoning navigation; The obtained estimated value is compared with the actual value actually measured based on the satellite radio waves of the predetermined satellite, and if the difference between the measured values is greater than a predetermined meter, the position is determined by the position calculation means. and a calculation stop command means for stopping the calculation, so as to stop the positioning calculation using interference waves as a counter-contamination to the calculation.

[Example] Hereinafter, the present invention will be described in detail using the accompanying drawings.

FIG. 1 is a block diagram of a GPS position 81 measuring device for a vehicle according to an embodiment of the present invention, FIG. 2 is a flowchart for synchronous monitoring processing, and FIG. 3 is an explanatory diagram of the running state of the vehicle. FIG. 4 is an explanatory diagram showing an outline of calculations in clj in the synchronization monitoring process.

This example shows an example of a GPS position measuring device that detects reflected waves as interference waves and takes measures to stop positioning calculations for the reflected waves.

To briefly explain the principle of the receiver, as shown in FIG. is amplified. On the other hand, the same PN signal as that on the satellite side is generated from the PN signal generator 5, and this is multiplied by the signal output from the broadband intermediate frequency amplifier 4 in the mixer 6, and then input to the band pass filter 7. Ru.

At this time, it is necessary to completely overlap the PN code of the PN signal generator 5 and the PN code of the received signal.
(+)]9 is provided.

The PN phase difference detector 8 detects the phase difference between the two PN codes, changes the frequency of the voltage controlled oscillator based on the difference, and controls the phase of the PN signal generator 5.

The signal that has passed through the band pass filter 7 is multiplied by the signal output from the detection voltage control oscillator [VC○(2)] 10 in the mixer 11, and then passed through the low pass filter 12. The signal is passed through, converted into a data code, and output to the central processing unit 15 via a data detection filter 14 controlled by a bit synchronization controller 13.

Phase synchronization between the signal oscillated by the voltage 1iIJti1 oscillator 10 and the signal passed through the bandpass filter 7 is performed by a carrier tracking circuit composed of two frequency doublers 16, 17 and a mixing PJ 18.

Since the carrier wave oscillated by the voltage fi controlled oscillator 10 has a Doppler shift of the same value as the received band, by taking the difference between this and the reference signal generated by the stable oscillator 19, the carrier wave between the WI star and the receiver is calculated. ? A Doppler count corresponding to one linear velocity is measured by a Doppler measuring device 20.

Furthermore, the difference between the time generated by the clock generator 21 based on the signal oscillated by the stable oscillator 19 and the time generated by the PN signal generator 5 and generated by the clock generator 22 is measured. Accordingly, the cohesive distance is determined by the pseudo-range measuring device 23.

Based on the above principle, the central processing unit 15 can receive satellite data for a predetermined number of satellites from the data detection filter 14, and the earth P of the vehicle, which is the object to be positioned! ! The three-dimensional position on the elevation will be measured.

The attached dead reckoning navigation device 25 is connected to a direction sensor and a vehicle speed sensor (not shown), and detects the movement m of the vehicle with respect to a reference position using vector values.

The synchronization monitoring device 24 functionally includes a straight-line distance calculation means that calculates the straight-line distance between the vehicle and the satellite as an estimated value, and a calculation stop command means that outputs a calculation stop command when a reflected wave is detected. are doing.

Synchronous supervisor? The operation of the fl device 24 is shown in FIG.

Step 201 shows the process of taking in the output signal of the voltage controlled fI1 oscillator 9.

Step 202 shifts the synchronization timing f based on the frequency of the input voltage 11111un signal from the oscillator 9.
7J shows the process of calculating ffiΔt.

In step 203, the dead reckoning device 25 sends the vehicle
This shows the process of inputting ta as a vector value (azimuth and distance ti>).

In step 204, the central processing unit 15 determines the elevation angle θ of the satellite.
This shows the process of inputting azimuth data.

Step 205 is a synchronization timing shift 1FJI ffi
It shows the process of calculating the predicted value ΔT'. This n-output method will be explained using FIGS. 3 and 4.

'As shown in the IS3 diagram, the vehicle 26 is at a predetermined 1f at point PA.
It is assumed that positioning is performed by receiving the signal Wa of star fi S1 and other satellite signals, and then the next positioning is performed when the vehicle moves to point Pa. At point PA, the exact position is required because all 9 signals are directly received, but at point PB, the direct wave wb from satellite Si is blocked by buildings and the reflected wave wb -, which has a long propagation path, is received, so measurements were taken. The position error becomes large.

Therefore, the purpose of this calculation is to eliminate positioning errors caused by such reflected waves Wb'. Vehicle 26 is at point PA
The position of satellite 3i when it is at point P[3 is assumed to be PSA, and the position when it is at point P[3 is PSa.

First, referring to FIG. 4, in step 203,
Using the input dead reckoning data, the position PSn of the satellite 3i after movement and the position i? of the vehicle 26 after movement are determined. ? Assuming a plane F that includes a straight line LB connecting the plane Ps and intersects the road surface 27 at right angles, the projected distance a of the movement m of the vehicle 2G onto the plane F is determined.

Second, the vehicle position PA before movement and the satellite position PS after movement.
1) Find the ILM. Vehicle position P before movement
A is determined three-dimensionally in the previous positioning, and t=
Satellite position after movement PSB4. is determined from the orbit data, so this distance 11L1. l is uniquely determined.

Thirdly, the distance LB and distance! ! 1ffL1. Difference from l△
Find 1-1.

△L+ = LM - Ln = a - cos θ Fourth, the vehicle position PA before movement and the satellite position PSA before movement
Let LA be the distance between the two, and calculate the distance difference ΔL between the distance LB and the distance MLA.

8L=LB-LA=toL++(LM-LA)=ΔL1+ΔL2 Fifth, the above distance l1li difference ΔL is divided by the speed of light to obtain the predicted synchronization timing movement amount ΔT'.

The predicted value Δ of the movement amount of the synchronization timing obtained in this way
If the radio waves from the satellite St reach the small mountain directly, T- is the PN phase difference detector 8. at the point ρB after moving. Voltage control transmitter9. This shows the amount of movement of the timing at which synchronization can be achieved in the PLL constituted by the PN signal generator 5.

Returning to FIG. 2, step 206 is the PN phase difference detector 8.
3 shows a process of determining whether the PLL is out of synchronization based on a signal output from the PLL. The inability to synchronize is caused by the occurrence of ringtones, diffused reflections, etc. If synchronization is not possible,
The process moves to step 209, and if synchronization is not impossible, the process moves to step 207.

Step 207 calculates the shift amount Δ of the synchronization timing outputted in step 202 and the shift of the synchronization timing predicted in step 205! It shows the process of comparing IJ FlyAT'.

Step 208 is to determine the comparison result of step 207, and if the comparison result substantially matches, it is determined that the radio waves from satellite Si are almost directly incident on the vehicle, and the process is interrupted here, and the comparison is made. If there is a slight difference in the results, step 2
Processing is moved to step 10. Step 209 is 11
F A predicted value of synchronization timing corresponding to the current position of the vehicle is obtained based on navigation data and satellite data, and this is output to the voltage controlled oscillator 9.

Step 210 is for outputting a position calculation stop signal to the central processing unit 15 based on the inability to synchronize P L L or based on the fact that the movement amount of the synchronization timing is significantly different from the predicted value. .

As mentioned above, in this embodiment, the GPS position 1
In one device, the synchronization failure state of the PLL is detected and a prediction of the amount of movement of the synchronization timing at the time of reception is made, and when synchronization is impossible and the actual value of the movement amount of the synchronization timing is significantly different from the predicted value, the central processing 5A The positioning calculation at position 15 can be stopped.

Therefore, in the GPS position measuring device according to this example, reflected waves,
Since it is possible to effectively detect out-of-synchronization due to interference waves such as noise and stop positioning calculations as appropriate, the central processing unit 1
5 errors in positioning calculation can be prevented.

In addition, in this example, the predicted synchronization timing is determined by the voltage controlled oscillator 9.
Since the synchronization monitoring device 24 is configured to output to It is.

[Effects of the Invention] As described above, according to the present invention, it is possible to prevent the adverse effects of radio waves other than direct waves such as reflected waves, and to smoothly perform highly sensitive positioning. The neck can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a GPS position measuring device for a vehicle according to an embodiment of the present invention, FIG. 2 is a flowchart from t-1 showing the synchronization monitoring process, and FIG. 3 is an explanatory diagram of the running state of the vehicle. FIG. 4 is an explanatory diagram showing an outline of operation c7 in the synchronization monitoring process. 5...PNIΔ generator 8...PN phase difference detector 9...Voltage controlled oscillator 24...Synchronization monitoring device 25...Dead reckoning navigation device

Claims (2)

[Claims] (1) A satellite acquisition means that captures satellite radio waves, a position calculation means that calculates the position of the object based on satellite data such as the straight-line distance from the captured satellite, and a dead reckoning method to determine the current position of the object. a straight-line distance calculation means for calculating the straight-line distance between the object to be measured and a predetermined satellite as an estimated value; and a computation stop command means for discontinuing the position computation in the position computation means when the difference between the actual measured value and the estimated value is greater than a predetermined amount.
PS position measuring device. (2) The estimated value and the measured value are calculated by converting them into radio wave propagation delay times.
PS position measuring device.