JPH03108681A - Gps receiver - Google Patents

Abstract

PURPOSE:To obtain an apparatus enabling precise measurement of a position at all times by a method wherein a plurality of GPS satellites are selected by a position- measuring position computing means, a position-measuring position is computed for each combination of the satellites, and the position is determined by a GPS satellite determining means on the basis of the degree of dispersion of the position. CONSTITUTION:Signals fG emitted by GPS satellites 5 are inputted to a reception processing element 2 of an apparatus 10, and after they are amplified and demodulated, the orbit and pseudo-data of each satellite 5 are computed from the data of the signals and stored in a memory 3 for the reception processing element 2, while a position- measuring position is obtained simultaneously by using them. Then, three of four satellites 5 are selected from the ones wherefrom the signals can be received and the computation of the position-measuring position is executed for each of these satellites 5, while the dispersion of a computed value is determined. When this is a prescribed reference value or above and the dispersion calculated for other than some specified GPS satellite is the prescribed reference value or below, this GPS satellite is regarded as an inadequate satellite deteriorating the precision of position measurement and not selected for the computation for the position measurement thereafter. According to this method, the position-measuring position can be obtained precisely.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to Global Positioning
G using System (hereinafter referred to as GPS)
A flash appears on the PS receiver.

(Prior art) Conventionally, as this type of device, for example, Japanese Patent Application Laid-open No. 61-19
The one described in Publication No. 8074 is known, and three or four GPS satellites are selected from among the receivable GPS satellites (three for two-dimensional positioning, four for three-dimensional positioning). The positioning satellites are selected using the combination that minimizes the DOP value, which indicates geometric accuracy divergence, in order to increase the positioning accuracy as a satellite selection criterion. It is configured to be

(Problem to be solved by the invention) However, in the conventional device as described in 1-1, the DO
The P value is an index value determined only by the satellite placement situation, and does not take into account the following errors.

(1) Errors caused by satellite position data.

(2) Error caused by ionospheric radio wave propagation delay.

(3) Error due to tropospheric radio wave propagation delay.

Therefore, the combination of satellites with the minimum DOP value is not necessarily the optimal f? There was a problem that it was not a combination of i stars.

This invention has been made in view of the following problems: 1-) To perform positioning calculations by excluding GPS satellites whose positioning accuracy decreases when used for positioning calculations among receivable GI'S satellites. The objective is to provide a GI'S receiving device that can always perform accurate positioning.

(Means for solving the problem) This invention has the following features: 1. In order to solve the problems mentioned above, the system is constructed as shown in Fig. 1, and is designed to receive radio waves from a plurality of GPS satellites and calculate a measured position.

Then, the positioning position calculation means a selects a GPS satellite by changing the combination of satellites from among the plurality of GPS satellites, and calculates the positioning position for each selected combination of GPS satellites.

In addition, the GI'S satellite determining means uses the degree of dispersion of the positioning position calculated by the positioning position calculation means a.
A combination of PS satellites is determined.

(Operation) In this invention, a plurality of GPS satellites are selected, a positioning position calculation is performed for each combination of the selected satellites, the variance of the calculated positioning position is calculated, and the GPS satellite is determined based on the degree of variance. Determine the combination of

(Description of Embodiments) Next, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 is a block diagram showing the basic configuration of the first embodiment to which the present invention is applied.

In the same figure, a portion 10 surrounded by a dashed-dotted line is a GPS receiver, and a signal f6 emitted from a GPS satellite 5 is manually inputted to a reception processing unit 2 via an antenna 1, and the signal is amplified.
After demodulation, the orbit data and pseudorange data of each satellite 5 are calculated from the demodulated data, and are stored in the reception processing unit memory 3.
The measured position is obtained using the data.

This calculated positional information is then output to the outside and used in a navigation system or the like.

By the way, in this embodiment, - in the reception processing section 2, a
Satellites whose positioning accuracy is estimated to deteriorate if used for the 11th position calculation are registered, and are configured not to be selected during subsequent positioning calculations for a certain period of time.

Hereinafter, the process procedure 1-1 executed by the reception processing unit 2 will be explained with reference to the flowchart shown in FIG.

In the same figure, when the program is started, the number of satellites 5 that can be received at present is counted, and the number of satellites 5 that can be received at present is counted. When 6 or more (1-) receivable satellites 5 are extracted (YES at step 1"00), 3 or 4 of them are extracted.
The satellites 5 are selected, positioning calculations are performed for all combinations, and the determined position and the combination of satellites used at that time are stored in the reception processing unit memory 3 (step 1).
10).

Here, if three satellites are selected and calculated, the positioning position of two-dimensional coordinates -1- is obtained, and if four satellites are selected and calculated, the positioning position of three-dimensional coordinates 1- is δi! IT1'/, the position will be determined. Which one to choose depends on GPS receiver 1
All you have to do is follow the request of the device connected to 0.

In addition, in the process of step 100, the reason for extracting one or more receivable satellites than the number originally required for positioning is because the combination of satellites is extracted in the process of registering satellites with poor accuracy described below. This is because a plurality of positioning positions that are calculated differently are required.

For example, when there are 5 receivable satellites, the combination of selecting 3 satellites from among them is s C3 = 10, so 10 different positioning positions can be obtained.

When each positioning position for each selected satellite is calculated in this way, the variance σ of the positioning position is calculated by calculating the standard deviation of each positioning position (step 120).

That is, a = ryx21-ry, y2 2 becomes.

n: Number of pieces of J1 Ma: (I ratio in the xh direction f: y) I4 ratio in the j direction Here, if this variance σ is less than the predetermined reference value α, then (
YES in step 130)1. It is thought that there are satellites with poor accuracy among the receivable satellites, so step 1
If the variance σ is less than the reference value α (NO in step 130), it is determined that there are no satellites with poor accuracy, and the lever program is terminated.

Then, in step 3.40, focusing on one satellite, a specific satellite i is measured by a combination of 3 rare and 1
It is checked whether there is a position where the variance σ(i) of the η positions is less than or equal to the reference value α. If only one such satellite is found (YES in step 140), ;'q is regarded as a satellite with poor accuracy and stored in the memory 3 for the reception processing section.
(step 150).

On the other hand, if the variance σ(i) is not less than the reference value α, or if two or more satellites of 1° are found to be defective satellites (NO in step 140), the satellites with poor accuracy cannot be identified. Exit the program.

For example, the satellites that can be received are A, B, C, and D.

Five satellites of E are extracted, and from these five satellites, three
When selecting satellites, there are the following 10 combinations.

(1) A, B, C (2) A, B, D (3) A, B, E (4) A, C, D (5) A, C, E (6) A, D, E (7 ) B, C, D (8) B, C, E (9) B, D, E (!, 0) C, D, E Here, the measured positions from (1) to (i], O”) The variance σ of is 1− less than the reference value α, and for example, −1] is a combination in which the satellite is not used among the combinations (7) to (
When the dispersion σ(A) of the positioning positions up to 10) is less than the reference value α, it is considered that the i star Δ increases the dispersion, so the satellite is presumed to be a defective satellite.

Therefore, if only one such satellite can be found, that satellite will be registered as a defective satellite.

In this embodiment, 3 satellites are selected from among the receivable satellites as described in 1-1.
Select one or four satellites, calculate the positioning position for each selected satellite, and find the variance of these calculated values,
If the variance is less than a predetermined reference value and a specific G
P By executing the process as described in -1- in parallel with the positioning calculation and not using the satellites registered in step 15 (1) for subsequent positioning calculations, it is possible to obtain the positioning position with high accuracy. Become.

On the other hand, when using the DOP value, depending on the geometrical arrangement of the satellite, it may be considered a defective satellite even if the accuracy of the satellite itself has not deteriorated. However, in this example, when used for positioning, Satellites whose positioning accuracy may deteriorate are registered without external support, so if the satellite placement situation changes after a certain period of time, they will be removed from registration as defective satellites in the next calculation and re-registered as normal satellites. It will be used for positioning.

In this way, in this embodiment, satellites that deteriorate positioning accuracy are registered without calculating the DOP value, and combinations of satellites that have poor geometric placement conditions that deteriorate positioning accuracy are automatically excluded. It turns out.

In addition, in step 11n, positioning calculations are performed for each combination of selected satellites, but in order to reduce the burden of calculation processing or to register defective satellites with high accuracy, the DOP value is calculated in advance and the DOP value is calculated in advance. Step 110 is performed only for combinations whose values are equal to or less than a predetermined value.
The following calculation may be performed.

In addition, in the case of a receiving device with low calculation processing capacity, it is a heavy burden to perform the registration process of unselected satellites as described above in parallel with the positioning calculation, but in this case, the GPS receiving device is not moving. It is also possible to perform the above processing only occasionally. For example, when the program is mounted on a vehicle, it may be executed while the vehicle is stopped.

Furthermore, if the process described in -1- is executed only when the vehicle is stopped or when the vehicle speed is below a certain level, the accuracy of the variance σ obtained in step 120 will be improved. If the vehicle is installed in a vehicle, it may be determined whether or not the vehicle speed is below a predetermined reference vehicle speed before the processing in step 100, and the processing in steps 100 and subsequent steps may be performed only if the vehicle speed is below the predetermined reference vehicle speed. It is possible.

Next, a second embodiment of the invention will be described. Note that this second embodiment differs from the first embodiment only in the GPS satellite selection processing procedure executed by the reception processing section 2, and the basic configuration of the device is the same as shown in FIG. - to 2nd 1st
Since this embodiment is exactly the same as that of the embodiment, the explanation thereof will be omitted.

Therefore, the GPS satellite selection processing procedure executed by the reception processing section 2 will be explained below with reference to flowchart 1 in FIG.

First, in the processing of steps 200 and 210, as in the first embodiment, five or more receivable satellites are extracted, and from among these, three or one satellite is extracted by changing the combination of satellites. satellites are selected, and the positioning position is calculated for each combination of the selected satellites.

Then, in the subsequent step 220, the variance σ(i) of the calculated positioning positions is calculated by excluding one specific satellite i from the extracted satellites.

For example, the satellites that can be received are A, B, C, and D.
.

There are 5 satellites of E, and the combinations for selecting 3 satellites from among them are as described above, as described in -1- (1) to (10
) There are 10 ways.

For example, if we start with satellite, the combinations excluding satellite are (7), (8), and (9).

There are four ways (10). Therefore, the variance σ(A) of the positioning position obtained by these four combinations excluding the satellite is defined as the variance σ(A).

Then, in the subsequent steps 230 and 240, all the extracted satellites are focused on and the variance of the calculated position is calculated excluding the satellites.

Therefore, for example, in the example described in 1-1, satellite B was excluded (4
) , (5) , (6) , (Il]) The variance σ(B) of the measured 11γ positions is determined by the four combinations of (Il).

Furthermore, σ(C), σ(D), and σ(E) are determined in the same manner.

In this way, once the variance of the positioning positions calculated for all the extracted satellites excluding one satellite is determined (NO in step 230), the priority order of each satellite is determined based on the magnitude of the variance (step 250).

For example, the variance calculated excluding satellites A, B, C, D, and E is σ(8) 〉σ(B) 〉σ(C) 〉σ(D) 〉σ
(E) (1) If Satellite B is excluded than Satellite A, then Satellite B
Since the variance is smaller when excluding satellite A, it is presumed that the positioning accuracy is worse for a combination that includes satellite B than for satellite A. Therefore, in this case, the priority level for the satellite is set higher than for satellite B.

Therefore, when the dispersion order as shown in equation (1) is obtained, the priority of each satellite is determined in the order of A, B, C, D, and E.

The above processing is performed in parallel with normal positioning calculations, and during positioning calculations, satellites to be used are selected according to the 1-2 priority order.

Therefore, in the example in I-, A and B have high priority.

Three satellites C are selected and positioning calculations are performed. For example, if satellite A is blocked by a building or the like and cannot be received, the next highest priority satellite is used instead.

The second embodiment prioritizes receivable satellites (=J) and selects the satellite to be used so that the positioning accuracy is the highest. This means that it is possible to calculate the proximal position with higher accuracy <i':IIJ compared to the above.

(Effects of the Invention) As described in -, the GPS receiving device selects a plurality of GPS satellites, calculates the positioning position for each selected satellite, and calculates the variance of the calculated positioning position. Since the combination of GPS satellites is determined based on the degree of dispersion, defective satellites that degrade positioning accuracy are automatically eliminated, and the accuracy is always maintained without external support.
? It has effects such as being able to calculate the 1st position.

[Brief explanation of drawings]

Fig. 1 is a corresponding diagram of glue 1/no 1 of the present invention, Fig. 2 is a block diagram showing the basic configuration of the first embodiment, and Fig. 3 is a flowchart 1 showing the processing procedure of the first embodiment. Figure 4 is the second
2 is a flowchart showing the processing procedure of the embodiment. 1... Antenna 2... Reception processing unit 3... Memory for reception processing unit 5... GPS satellite 10... GPS receiving device

Claims (1)

[Claims] 1. In a GPS receiving device that receives radio waves from a plurality of GPS satellites and calculates a positioning position, a GPS satellite is selected by changing the combination of satellites from among the plurality of GPS satellites, and the selected GPS satellite is selected. and a GPS satellite determining means for determining the combination of GPS satellites based on the degree of dispersion of the positioning positions calculated by the positioning position calculation means. A GPS receiving device characterized by: