JP2000275320A - Gps receiver and gps reception method applied to the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of the navigating/positioning accuracy and navigation/positioning of a GPS receiver. SOLUTION: When the position of a user having a GPS(global positioning system) receiver and the initial estimated value of a clock error are set (step S11), the GPS receiver sets the parameter value indicating the state of its own device (step S12), acquires the observation data of all visible GPS satellites (step S13), and evaluates a Lagrangian factor term (step S14). Then the receiver successively solves navigation equations based on the evaluated results (step S15) and sets the status parameter of its own device by performing the processing in the step S12 based on the calculated results of the equations. Namely, the receiver sets a threshold for evaluating the quality of observation data from the visible GPS satellites.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a GPS (Global
Positioning System) A GPS receiver that measures the position of its own device using a satellite, and a GP applied to this device.
In the S receiving method, particularly, navigation or positioning accuracy and reliability in navigation or positioning are improved.

[0002]

2. Description of the Related Art As is well known, a GPS receiver mounted on a mobile body such as an automobile receives a satellite signal from a GPS satellite, for example, and determines a moving direction and a moving position of the mobile body from the received signal. Measuring. This type of GPS receiver can receive satellite signals from four visible GPS satellites. That is, in this GPS receiving apparatus, when satellite signals from four or more visible GPS satellites are received and positioning is continuously performed, a GPS satellite with a minimum positioning error is predicted, and the GPS satellite is moved with movement. The GPS satellites to be received are switched one after another so that the positioning accuracy is always optimized.

However, in the above-mentioned GPS receiving apparatus, positioning is performed using satellite signals from four GPS satellites. However, if there is a large error in one satellite signal, positioning is performed using three satellite signals, so that positioning accuracy is large. This has the effect of reducing the reliability of navigation or positioning. In addition, navigation or positioning data is discontinuous due to switching of GPS satellites. In addition,
An error is given in advance to a satellite signal from a GPS satellite, and also in a system that performs differential navigation, an error is given to, for example, orbit data from a ground station.

[0004] Therefore, recently, a GPS receiving apparatus which can suppress discontinuity of navigation or positioning data due to switching of GPS satellites, improve accuracy, and further ensure scalability to differential navigation. Improvement is strongly desired.

[0005]

As described above, in the conventional GPS receiver, positioning is performed using satellite signals from four GPS satellites. However, if one satellite signal has a large error, three satellite signals are used. Since positioning is performed by satellite signals, positioning accuracy is greatly affected, and there is a problem that reliability in navigation or positioning is reduced. There is also a problem that the navigation or the positioning data becomes discontinuous due to the switching of the GPS satellites.

An object of the present invention is to provide a GPS capable of minimizing the discontinuity of navigation / positioning data due to switching of a selected satellite and improving the navigation / positioning accuracy and the reliability in navigation / positioning. An object of the present invention is to provide a receiving device and a GPS receiving method applied to the receiving device.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided a GPS receiving apparatus for measuring the position of an own apparatus using a GPS satellite, receiving means for receiving satellite signals from all visible GPS satellites, and the receiving means. Observation data extraction means for extracting observation data including pseudorange data or carrier phase data relating to the visible GPS satellites and broadcast calendar data of the visible GPS satellites from the obtained satellite signals of all the visible GPS satellites, and this observation data extraction means Error observation value calculation means for inputting the observation data of all the visible GPS satellites obtained in the above and calculating the error value given to the satellite signal or the error estimation value which gives the maximum to the estimation probability of the error value occurring in the own device. And, based on the error estimation value calculated by the error estimation value calculation means, the observation data of all the visible GPS satellites obtained by the reception means. Observation data from the necessary GPS satellites is obtained as provided with the observed data determining means for determining.

According to this configuration, observation data from all the visible GPS satellites is fetched, and the maximum probability is given to the error value given to the satellite signal or the estimation probability of the error value occurring in the own device using these observation data. An estimated value of the error is calculated, and the required observation data from the GPS satellites is determined from the observation data of all the visible GPS satellites based on the estimated error value. That is, input observation data,
An estimated value of the error that maximizes the estimated probability is calculated, and the observed data and the visible GPS estimated based on the estimated value are calculated.
By comparing and checking the observation data of all satellites, the quality of the observation data can be evaluated, and based on this result, observation data with a deviation of less than a predetermined value can be selected as highly reliable observation data, and deviations larger than the predetermined value can be selected. Observation data can be discarded because it is judged to be unreliable observation data.

For this reason, it can be seen in normal navigation,
Since the discontinuity of navigation / positioning data due to switching of the selected satellite is minimized and the available observation data is optimally used, the navigation / positioning accuracy and the reliability in navigation / positioning are improved. It becomes possible to plan. Furthermore, resistance to quality deterioration of some observation data due to a failure of a GPS satellite or the like can be obtained.

In the above configuration, the receiving means has means for receiving a ground station signal transmitted from a ground station installed at a predetermined position and containing pseudorange data and observation time data by the ground station. The observation data extraction means has means for extracting pseudorange data and observation time data from the ground station signal received by the reception means, and the error estimation value calculation means calculates pseudorange data and observation time data by the ground station. The apparatus further comprises means for calculating an estimated value for inputting the maximum value to the estimation probability of the error value of the observation satellite position by the ground station. By doing so, highly accurate and highly reliable navigation can be realized when performing differential navigation.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit block diagram showing an embodiment of a GPS receiver according to the present invention. FIG. 2 is a diagram showing a positional relationship between the GPS receiver and a plurality of GPS satellites and a positioning concept.

In FIG. 1, for example, a GPS satellite signal transmitted from a GPS satellite is received by an antenna 11,
Immediately thereafter, the signal is low-noise amplified by the low-noise amplifier 12, converted into an RF (Radio Frequency) signal, and supplied to one input terminal of the multiplier 13. The other input terminal of the multiplier 13 has a GPS signal generated from the local oscillator 14 connected thereto.
A first local signal is provided which is obtained by multiplying a local signal having a center frequency by a multiplier 15. Then, the multiplier 13 performs frequency conversion to an IF (intermediate frequency) band by multiplying the RF signal by the first local signal.

The IF signal is a visible GPS satellite signal that can be received at that time, and a plurality of predetermined amplitudes are spread in accordance with a PN (pseudo noise) code for identifying each GPS satellite. This IF signal is supplied to the baseband units 101 to 10N, respectively.

In the baseband processing section 101, the input IF signal is supplied to one input terminal of the PN code canceler 16. The other input terminal of the PN code canceler 16 is supplied with a PN code oscillation signal generated by the PN code generator 17 and assigned to the own device. Then, the PN code release unit 16 outputs the P signal to the IF signal.
Despread by multiplying the N code oscillation signal,
Each GPS satellite signal assigned to the own device can be extracted. Therefore, the baseband processing units 101 to 10
The number N is the number of channels of the GPS receiver and is the maximum number of receivable satellites.

The satellite identification signal extracted by the PN code canceler 16 is supplied to a phase comparator 18 where it is transmitted to an NC.
G generated by O (Newmedical Control Ocial) 19
By comparing the phase with the second local signal having the PS center frequency, the phase difference component is extracted as a received signal. This reception signal is supplied to the reception control unit 200.

The reception control unit 200 calculates a PN code phase set value to be set in the PN code generator 17 and a carrier phase set value to be set in the NCO 19 in real time based on the input received signal. A certain PN code phase setting signal and a carrier phase setting signal are supplied to a PN code generator 17 and an NCO 19, respectively, so as to perform a phase tracking for signals input to a PN code canceler 16 and a phase comparator 18, respectively. In addition, the reception control unit 200 performs positioning of observation data including pseudorange data or carrier phase data calculated based on the input received signal and broadcast GPS data of a visible GPS satellite obtained by demodulating the received signal. Output to the arithmetic unit 300. This processing is performed for each of the baseband units 101 to 10N.
Is performed independently for each GPS satellite signal.

The positioning operation section 300 executes positioning operation processing based on observation data for each of the baseband processing sections 101 to 10N, thereby obtaining positioning data indicating the position of the own apparatus. The positioning data obtained here is, as shown in FIG. 2, three-dimensional information (X, Y, Z) indicating the position of the GPS receiver viewed from, for example, four GPS satellites 401 to 404, and the change (speed). (DX / dt, dY)
/ Dt, dZ / dt).

In FIG. 2, the GPS receiver is
Position information of the X component in the own device is obtained using the GPS satellite 401, position information of the Y component in the own device is obtained using the GPS satellite 402, and Z component in the own device is used using the GPS satellite 403. Is obtained.
Further, the operation time information of the own device can be obtained using the GPS satellite 404.

The above is the configuration of a general GPS receiver.

Next, the visible G in the GPS receiver is
The concept of processing observation data from the entire PS satellite will be described. First, in the conventional GPS receiving apparatus, one of the information is incorrect because the position of the own apparatus is measured using the three-dimensional position information (X, Y, Z) and the time information (T). It is highly possible that the data is insufficient and a large error occurs due to lack of data.

Therefore, the present invention fetches satellite signals from all visible GPS satellites and determines high quality observation data using the majority rule. That is, satellite signals from all visible GPS satellites to be received include each GPS
The error includes an error given in advance by a satellite and an error generated in the GPS receiver.

The positioning operation unit 300 receives the observation data of all the visible GPS satellites supplied from the reception control unit 200 and gives the maximum to the error value given to the satellite signal or the estimation probability of the error value generated in the own device. Calculate the estimated value of the error. That is, as an expression for obtaining the error estimates, introduced TOTAL Lagrangian (total Lagrangian) as shown in the following equation (1), TOTAL Lagrangian: L (Δz "G, Δz ') = L1 + L2 + L3 + L4 ... (1) below By solving the variational equation for this Lagrange shown in Expression (2), an estimated value of the user position / clock error that gives the maximum estimated probability is calculated.

Navigation equation: ∂L / ∂Δz ″ ^G = 0 ∂L / ∂Δz ′ = 0 (2) where Δz ″ ^G is a value obtained from broadcast calendar data on the position / clock error of the visible GPS satellite ♯G. SAGNAC for deviation
It shows the effect, that is, the value to which the correction coefficient by the rotation of the earth is added. Δz ′ is a four-dimensional variable representing the deviation of the user's position from the pre-update position and the clock error of the own device, which is the estimation target.

Next, the meaning and operation of each of the above L1, L2, L3 and L4 terms used in the total Lagrange will be described. First, L1 is a Lagrangian equation of a priori estimation of the GPS receiver position / clock deviation, and is given by the following equation (3).

(Equation 1)

Here, S is a covariance matrix before acquisition / update of observation data. That is, L1 represents the estimation of the state of the GPS receiver immediately before the observation is performed.

L2 is the Lagrange's equation for estimating the position of the GPS receiver, and is expressed by the following equation (4).

(Equation 2)

Here, σ _GR is the GP obtained by the GPS receiver.
This is the receiver error level of the S satellite $ G. ε _G is a data adoption flag, which takes 1 or 0 according to whether or not to adopt data of the GPS satellite ΔG. V ^G is the time component 1
And a four-dimensional vector composed of unit vectors in the direction of the GPS satellite ♯G as viewed from the position of the GPS receiver before the estimation update as a spatial component. Δy ^G is a guided observation amount calculated in consideration of ionospheric propagation delay correction and tropospheric propagation delay correction to observation data (pseudorange). Σ _G is visible GPS
Represents the sum of all satellites. That is, L2 is the visible G
This indicates the state estimation resulting from the observation data for the PS satellite.

Next, L3 is the Lagrange's equation for a priori estimation relating to the satellite position / clock error, and is given by the following equation (5).

(Equation 3)

Here, σ _GE represents the ephemeris accuracy of the GPS satellite ΔG. That is, the satellite position information provided by the GPS satellite broadcast calendar is not completely accurate, and accuracy information is also added thereto. Thus, the satellite position / clock error calculated from the satellite broadcast calendar is also weighted according to the accuracy information and used as an estimated variable.

Next, L4 is a Lagrange's equation for estimating the satellite position observed by the ground station installed at a predetermined position, and is given by the following equation (6).

(Equation 4)

Here, σ _GB is, for example, G
It represents the receiver error level of PS satellite $ G. That is, L4 is introduced when performing differential navigation. When the differential navigation is not performed, L4 becomes 0. Σ _GB
Is the sum of all visible GPS satellites at ground station B.

Next, the processing of the positioning operation unit 300 using the Lagrangian equation will be described with reference to the flowcharts of FIGS. In FIG. 3, the positioning calculation unit 3
First, when an initial estimated value of the position and clock error of the user who owns the GPS receiving device is set (step S11), a parameter value indicating the state of the own device is set (step S12), and the visible GPS satellite is set. All observation data is acquired (step S13), and the Lagrange element term is evaluated (step S14). That is, the above L1,
The parameter values in the terms L2, L3, L4 are evaluated. Then, based on the evaluation result, a sequential solution of the navigation equation is performed (step S15), and based on the calculation result, the state parameter of the own device is set in the process of step S12. That is, a threshold for evaluating the quality of observation data from the visible GPS satellites is set.

FIG. 4 shows the details of the processing in step S14. That is, the positioning calculation unit 300, at the time when the observation data of all the visible GPS satellites is input in step S13, the Lagrange element terms L1, L2, L3,
It is determined whether or not L4 is equal to or greater than a predetermined value (step S1).
41), when the predetermined value is not satisfied (NG), it is determined whether or not two consecutive NGs (step S142).
In the case of two consecutive NGs (YES), it is determined whether or not the number of visible GPS satellites is greater than four. If the number is greater than 4 (YES), the Lagrange element term L
2. The parameter value ε _{G of} L4 is set to 0 (step S144), and the observation data is rejected. If the evaluation value is equal to or more than the predetermined value in step S141 (GOOD) or if the NG is only once in step S142 (NO), the visible GPS is determined in step S143.
If the number of satellites is 4 or less (NO), ε _G is set to 1 (step S145).

FIG. 5 shows the details of the processing in step S15. That is, the positioning calculation unit 300
By solving the navigation equation as shown in the above equation (2), error estimation values Δz ′, Δz ″ ^G at which the estimation probability becomes the maximum are obtained (step S151).
It is determined whether the observation data input to the observation data estimated based on Δz ″ ^G converges (step S15).
2) In the case of convergence (YES), the state parameters set in the GPS receiver are updated (step S).
153). In step S152, if the convergence does not occur (NO), it is determined whether the sequential solution of the navigation equation has been performed more than three times (step S154). (Step S155).

As described above, according to the above-described embodiment, the positioning calculation unit 300 fetches observation data from all visible GPS satellites, and uses these observation data to obtain an error value given to a satellite signal or its own device. An error estimation value that gives the maximum to the estimation probability of the error value that occurs in is calculated, and based on the error estimation value, required observation data from GPS satellites is determined from observation data of all visible GPS satellites.
That is, the positioning calculation unit 300 receives the observation data of all the visible GPS satellites, calculates an error estimation value that gives the maximum to the estimation probability of the error value, and compares the observation data estimated based on the error estimation value with the actual observation data. The quality of the observation data can be evaluated by comparing and checking the observation data of all visible GPS satellites, and based on the result, the observation data with a deviation of a predetermined value or less can be selected as highly reliable observation data, and the predetermined value can be selected. Observation data with a larger deviation can be judged as unreliable observation data and rejected.

For this reason, it can be seen in normal navigation,
Discontinuity of navigation / positioning data due to switching of selected satellites is minimized, and optimal use of available observation data improves navigation / positioning accuracy and reliability in navigation / positioning. It becomes possible. Furthermore, resistance to quality deterioration of some observation data due to multipath or the like can be obtained.

Further, when performing the differential navigation, since it is secured by adding the Lagrange element term L4 as shown in the above equation (1), the extension to the differential navigation is simplified. Further, since each term constituting the above equation (1) is given in a quadratic form of the observation residual, when the number of visible GPS satellites is larger than 4, ε _G = 0 is set, so that low reliability observation is performed. Data can be rejected.

Further, if the GPS receiver according to the above embodiment is used, the navigation of the currently used automobile and ship,
In addition, the present invention can be immediately implemented for civil engineering, construction, surveying positioning, and the like, and highly accurate positioning and navigation can be realized.

In the above embodiment, the total Lagrangian equation is used as an operation algorithm for calculating the estimated value of the error, but the least square method for minimizing the estimated error value is also used in the same manner. Can be implemented.

In addition, the configuration of the GPS receiver, the operation algorithm for calculating the estimated value of the error, and the like can be variously modified without departing from the gist of the present invention.

[0041]

As described in detail above, according to the present invention,
The present invention is applied to a GPS receiver and a GPS receiver capable of minimizing discontinuity of navigation / positioning data due to switching of a selected satellite and improving navigation / positioning accuracy and reliability in navigation / positioning. A GPS receiving method can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a GPS receiver according to the present invention.

FIG. 2 shows a GPS receiver and a plurality of G's in the embodiment.
The figure which shows the positional relationship with a PS satellite, and a positioning concept.

FIG. 3 is a flowchart showing the operation of the positioning calculation unit shown in FIG. 1;

FIG. 4 is a flowchart showing a detailed process of step S14 shown in FIG. 3;

FIG. 5 is a flowchart showing a detailed process of step S15 shown in FIG. 3;

[Explanation of symbols]

11 antenna, 12 low-noise amplifier, 13 multiplier
14 local oscillator, 15 multiplier, 16 PN code canceller, 17 PN code generator, 18 phase comparator,
19 ... NCO (Newmedical Control Ocial), 101-1
0N: baseband processing unit, 200: reception control unit, 30
0: Positioning calculation unit, 401 to 404: GPS satellites.

Claims (14)

[Claims] 1. A GPS receiving device that measures the position of its own device using a GPS (Global Positioning System) satellite, receiving means for receiving satellite signals from all visible GPS satellites, Observation data extraction means for extracting observation data including pseudorange data or carrier phase data relating to the visible GPS satellites and broadcast calendar data of the visible GPS satellites from all satellite signals of the visible GPS satellites, Error estimation value calculation means for inputting observation data of all the visible GPS satellites and calculating an error value given to the satellite signal or an error estimation value which gives a maximum to an estimation probability of an error value occurring in the own device; Based on the estimated value calculated by the error estimated value calculating means, the observation data of all visible GPS satellites obtained by the receiving means GPS receiver apparatus characterized by comprising; and a monitoring data determining means for determining the observation data of al necessary GPS satellites. 2. The method according to claim 1, wherein the error estimation value calculating means is a visible GPS.
2. The GPS receiving apparatus according to claim 1, further comprising means for inputting observation data of all satellites and calculating an estimated value indicating a deviation of the position of the own apparatus from the pre-update position and a clock error of the own apparatus. . 3. The apparatus according to claim 2, wherein said error estimation value calculating means is a visible GPS.
Means for inputting observation data of all the satellites and calculating an estimated value indicating a value obtained by adding a correction coefficient due to the rotation of the earth to a deviation from the broadcast calendar data regarding the position / clock error of the visible GPS satellite. The GP according to claim 1,
S receiver. 4. The GPS according to claim 1, wherein said error estimated value calculating means further comprises means for calculating an estimated value that gives a maximum to an estimated probability of an error value of a position / clock of a visible GPS satellite. Receiver. 5. The receiving means has means for receiving a ground station signal transmitted from a ground station installed at a predetermined position and including pseudorange data and observation time data by the ground station. The data extracting means has means for extracting the pseudorange data and the observation time data from the ground station signal received by the receiving means, and the error estimation value calculating means has the pseudorange data and the observation data obtained by the ground station. 2. The GPS receiving apparatus according to claim 1, further comprising means for inputting time data and calculating an estimated value which gives a maximum to an estimated probability of an error value of an observation satellite position by the ground station. 6. The method according to claim 6, wherein the error estimation value calculating means includes a visible GPS
2. The GPS receiving apparatus according to claim 1, wherein the observation data of all the satellites is input, and an estimated value of the error is calculated by an arithmetic algorithm using Lagrange's equation. 7. The apparatus according to claim 1, wherein said error estimation value calculating means includes a visible GPS
2. The GPS receiving apparatus according to claim 1, wherein the observation data of all the satellites is input, and an estimated value of the error is calculated by an arithmetic algorithm using a least square method. 8. A GPS receiving method applied to a GPS receiving device that measures the position of its own device using GPS satellites, wherein satellite signals are received from all visible GPS satellites, and all of the obtained visible GPS satellites are received. Visible GPS from satellite signals
Extraction of observation data including pseudorange data or carrier phase data relating to satellites and broadcast calendar data of visible GPS satellites, and using the obtained observation data of all visible GPS satellites, an estimated error value given to the satellite signal Alternatively, an estimated value that gives the maximum to the estimated probability of the error value generated in the own device is calculated. Based on the calculated estimated value, observation data of the necessary GPS satellites is obtained from observation data of all the visible GPS satellites. A GPS receiving method, characterized by determining. 9. The GPS receiving method according to claim 8, wherein the estimated value indicates a deviation of the position of the GPS receiver from the pre-update position and a clock error of the GPS receiver. 10. The GPS receiving apparatus according to claim 8, wherein the estimated value indicates a value obtained by adding a correction coefficient due to the rotation of the earth to a deviation from broadcast calendar data relating to a position / clock error of a visible GPS satellite. Method. 11. The GPS receiving method according to claim 8, wherein the estimated value is further calculated such that the estimated probability of the error value of the position / clock of the visible GPS satellite is maximized. 12. When the GPS receiving apparatus receives a ground station signal including pseudo distance data and observation time data transmitted from a ground station installed at a predetermined position and received by the ground station, the GPS receiver receives the received GPS signal. The pseudo-range data and observation time data are extracted from the ground station signal, and the extracted pseudo-range data and observation time data by the ground station are input, and the estimation probability of the error value of the observation satellite position by the ground station is maximized. The GPS receiving method according to claim 8, wherein an estimated value to be given is calculated. 13. The GPS receiving method according to claim 8, wherein the estimated value is calculated by inputting observation data of all visible GPS satellites and using an arithmetic algorithm using Lagrange's equation. 14. The GPS receiving method according to claim 8, wherein the estimated value is calculated by inputting observation data of all visible GPS satellites and using an arithmetic algorithm using a least squares method.