JP3437870B2 - Post-mortem satellite positioning system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS (Global Posit
ioning System), GLONASS (GlobalOrbiting N)
The present invention relates to a satellite positioning system such as an avigation satellite system, and more particularly to a post-analysis satellite positioning system in which positioning information collected in a mobile station is collected in a base station and analyzed and corrected. [0002] Moving objects (vehicles, ships,
As a satellite positioning system for measuring (positioning) the position, speed, etc. of a human or the like), GPS developed by the US Department of Defense (DoD) and GLONASS developed in Russia
It has been known. In this type of system, information indicating the orbit of each positioning satellite such as ephemeris data and almanac data, clock data indicating time, and the like are transmitted from the positioning satellites in orbit around the earth after being spread spectrum. . A mobile unit on the earth is equipped with a receiver for receiving the orbit data. This receiver receives and demodulates orbit data etc. transmitted from positioning satellites,
The distance from the positioning satellite to the moving object is obtained by using the clock data received from the positioning satellite and the synchronization information (synchronization information to the carrier and the pseudo noise code) to the signal transmitted from the positioning satellite. This distance includes various errors such as an offset between the clock of the positioning satellite and the clock of the receiver, and the distance is called a pseudo distance. In the receiver, three or four positioning satellites that are considered to provide good positioning accuracy when viewed geometrically are selected from positioning satellites that are in a direction or situation in which the signal can be received, and at least this positioning satellite is selected. The above-mentioned orbit data and pseudo range are obtained for the satellite. If orbit data and pseudoranges are obtained for the selected three or four positioning satellites, the position of the moving object can be obtained by simultaneous polynomial operation based on these data. Further, by detecting a Doppler shift or the like of a signal received from a positioning satellite, it is possible to know the moving speed of the moving object. The reason why four positioning satellites are selected is that the pseudorange contains an error as described above, and this error needs to be treated as an unknown number. Further, there may be a case where three positioning satellites are sufficient, for example, when the altitude is known as in the case of a marine mobile object. In this type of satellite positioning system, the accuracy of a pseudo distance obtained by positioning in a mobile object is limited by, for example, the chip length of a pseudo noise code, and as a result, the accuracy of position and speed is also limited. I have. As a system configuration that overcomes such restrictions on accuracy,
There is a configuration that uses a base station whose exact position is known. This system configuration is called a differential system. In the differential system, positioning is performed in both a receiver (hereinafter, referred to as a mobile station) mounted on a mobile body and a base station. If the mobile station is relatively close to the base station, the pseudorange or position determined at the mobile station can be considered to include an error approximately equal to the pseudorange or position determined at the base station. Further, since the exact position of the base station is known, the error included in the pseudorange or position obtained at the base station can be obtained by comparison with the accurate position of the base station. Therefore, the position of the mobile station can be accurately known by correcting the pseudo distance or the position obtained at the mobile station with the error obtained at the base station. [0004] The differential system is a real-time type in which data is communicated between a mobile station and a base station using a data line such as a wireless line and correction is performed in real time, or a positioning information recorded in the mobile station is later transmitted to the base station. A post-analysis type that collects (takes) and corrects this using the positioning information recorded in the base station, and a pseudo-range or position obtained in the base station is supplied to the mobile station, and the mobile station receives a signal from a positioning satellite. And the non-correction type that does not perform reception. The real-time type is suitable for applications such as vehicle operation because the correction can be executed in real time.The post-analysis type is also suitable for environmental surveys, animal and plant behavior surveys, navigation data recording, tracking the movement trajectory of goods and machine tools, etc.
Suitable for applications that require data analysis. In addition, the post-mortem analysis type can be implemented without using a data line. Uncorrected type is
This is suitable when the mobile station does not require very accurate positioning information. [0005] In the differential system, the position of the mobile station is corrected by using the positioning error of the position, or the pseudorange from the mobile station to the positioning satellite is corrected by using the positioning error of the pseudorange. It can be classified into a correction method and a pseudo distance correction method. As shown in FIGS. 5A and 5B, in the position correction method, both the mobile station and the base station need to record the measurement time, the measurement position, the satellite used, and the positioning state. Here, “measurement time” indicates the time at which positioning was performed, “measurement position” indicates the position of the mobile station or base station obtained by positioning, “used satellite” indicates the combination of positioning satellites used for positioning, and “ Positioning status "
Indicates the effectiveness of positioning. FIG.
As shown in (a) and (b), in the pseudo distance correction method, it is necessary to record the measurement time, the measured raw data, the satellite used, and the reception state in both the mobile station and the base station. Here, "measured raw data" indicates pseudorange and orbit data obtained from the positioning satellite, and "reception state" indicates the reception state of a signal from each positioning satellite. [0006] The differential analysis system of the post-analysis type has an advantage that a data line is not required as described above. However, another problem arises when trying to implement this scheme. For example, it is assumed that a position correction method is adopted in a post-analysis type differential method. In this case, the mobile station only needs to record data having the contents shown in FIG. 5A, and does not need to record raw measurement data as in the pseudo distance correction method. Since the raw measurement data exists for each positioning satellite, it is generally a large amount of data.
Therefore, it can be said that such a position correction method that does not require recording of the raw measurement data is generally preferable for a mobile station having a physical limitation on the data recording capacity.
However, since the error included in the position obtained by positioning differs for each combination of positioning satellites selected for positioning, the base station performs comprehensive position calculation for all combinations of positioning satellites that can be selected by the mobile station. It is necessary to execute and record the measurement position. It is not realistic to perform such a large amount of data processing in the base station. [0008] It is also assumed that a pseudo-distance correction method is employed in the post-analysis type differential method. In this case, the base station only needs to record the raw measurement data for each positioning satellite that may be selected by the mobile station, so that the data processing in the base station is simpler than in the position correction method. In this regard, the pseudo distance correction method can be said to be a more realistic method. However, in this method, it is necessary to record raw measurement data as shown in FIGS. 6A and 6B, and a large amount of data must be recorded. This is a problem especially in a mobile station having a physical restriction on the recording capacity, and causes problems such as price and service time. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a combination of a position correction method and a pseudo distance correction method so that the advantages of both can be enjoyed. It is an object of the present invention to simplify processing and reduce the amount of data recorded in a mobile station, and to realize a system free from problems in terms of price and service. Another object of the present invention is to reduce the amount of data recorded in a base station. [0010] In order to achieve the above object, the present invention provides a mobile station and a base station, wherein information recorded in the mobile station is collected by the base station afterwards and analyzed and corrected. in post-mortem type satellite positioning system, means for the mobile station receives a signal from a positioning satellite of a predetermined number of selected from multiple <br/> number of positioning satellites, to measure the position of the own station based on the received signal , the selected positioning satellite, information identifying the issue time of the orbit data of the positioning satellites contained in the received signal, and means for recording the measured positions and a series of measurement time and measurement time thereof, the base station , which receives the trajectory data as a signal from all of the positioning satellites at least mobile stations among the above SL plurality of positioning satellites might be utilized, erroneous on the basis of the signal propagation time from the positioning satellite to the mobile station Comprising means for measuring a pseudorange including, your base station
The measurement time interval recorded during
The data recording frequency is longer than the measurement time interval
In addition, the base station is a positioning satellite that has received the orbit data, means for recording the received orbit data, the measured pseudorange and the measurement time thereof, and at least the local station among the measurement times recorded in the mobile station. If the measurement time coincides with the recorded measurement time , the position of the own station is determined based on the orbit data and the pseudorange of the positioning satellite selected in the mobile station, and the determined position of the own station is known. The correction amount is obtained by comparing with the exact position of
If the measurement time is not recorded in the mobile station,
In this case, the correction amount at the measurement time
Of the recorded measurement times, the
Multiple measurement times before and after the
Means for obtaining a correction amount by interpolation from the correction amount thus obtained, and correcting the position of the mobile station measured at the mobile station based on the obtained correction amount . According to the present invention, the mobile station records the selected positioning satellite, information for specifying the issue time of the orbit data, the measured position, and the measurement time. The information recorded at the mobile station is subsequently collected at the base station. on the other hand,
The base station receives the orbit data as signals from at least all positioning satellites that may be used by the mobile station, and measures the pseudorange. The base station records the positioning satellite that received the orbit data, the received orbit data, the measured pseudorange, and the measurement time. The base station determines, based on the orbit data and the pseudorange of the positioning satellite selected at the mobile station, at least the measurement time corresponding to the measurement time recorded at the mobile station among the measurement times recorded at the mobile station. Ask for. The base station further compares the determined position of the own station with a known accurate position of the own station, and corrects the position of the mobile station measured by the mobile station based on the result. Therefore, in the present invention,
Since it is not necessary for the base station to perform position calculation for each combination of positioning satellites, data processing at the base station is simplified. In addition, in the present invention, since the mobile station does not need to record the measured raw data such as the orbit data and the pseudo distance, the amount of data recorded in the mobile station is reduced, and a system free from problems in terms of price and service is provided. Is achieved. In the present invention, when correcting the position recorded by the mobile station, interpolation of the correction amount is performed at the base station. That is, when the measurement time not recorded in the own station is not recorded in the mobile station,
The base station obtains the correction amount at the measurement time by interpolation from the correction amounts obtained for a plurality of measurement times before and after the measurement time not recorded at the own station among the measurement times recorded at the own station. . Therefore, it is possible to make the interval of the measurement time recorded in the base station longer than the interval of the measurement time recorded in the mobile station, that is, it is possible to suppress the data recording frequency in the base station. Preferably reduced. Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a post-analysis satellite positioning system according to an embodiment of the present invention. This embodiment is an example in which the present invention is applied to a differential GPS. However, the present invention is also applicable to other systems that perform positioning using trajectory data, pseudoranges and the like, like GPS, for example, GLONASS. The ground portion (user portion) of this embodiment is:
It comprises a base station and a plurality of mobile stations moving within a predetermined range around the base station. Mobile station 1 includes antenna 1
1, a GPS receiver 12, a recorder 13, and a battery 14. The signal transmitted from the GPS satellite is GP
The signal is received by the S receiver 12 using the antenna 11.
The GPS receiver 12 demodulates orbit data of a GPS satellite from the received signal, and calculates a pseudo distance to the GPS satellite. The GPS receiver 12 performs this processing for at least three or four GPS satellites. Target GP
The S satellite, for example, evaluates the geometric arrangement of the GPS satellites and selects so as to obtain the highest positioning accuracy. GPS
The receiver 12 calculates the position and the like of the mobile station 1 using the orbit data, pseudorange, and the like of the selected GPS satellite. The recorder 13 is, as shown in FIG.
2, the position of the mobile station 1 (measurement position), the time at which the measurement position was obtained (measurement time), the combination of GPS satellites selected to obtain the measurement position (use satellite), the orbit of the satellite used The data issue number (IODE) and information indicating the validity of the positioning operation (positioning state) are recorded on the data file 15. If the number of mobile stations is large, an identification code for identifying the mobile station is also recorded on the data file 15. Further, information obtained by various sensors (for example, information obtained by environmental observation, etc.) may be recorded on the data file 15 together. The battery 14 is a portable / portable power supply that supplies power to each unit of the mobile station 1. The mobile station 2 also has an antenna 21, a GPS receiver 22, and a recorder 23 having similar functions.
And the battery 24, and the data file 2
5 and the same information is recorded. The base station 3 comprises an antenna 31, a GPS receiver 32, a recorder 33, a power supply 34, and a processing device 36. The signal transmitted from the GPS satellite is GPS
The signal is received by the receiver 32 using the antenna 31. G
The PS receiver 32 demodulates orbit data of a GPS satellite from the received signal, and obtains a pseudo distance to the GPS satellite. The GPS receiver 32 performs this processing for each of all the GPS satellites that can be used in the mobile stations (1, 2,...) Existing around the GPS receiver 32. GPS receiver 1
2 is a GPS receiver (12, 2, 2) of the mobile station (1, 2,...).
Unlike the case of (2,...), Processing for obtaining a position or the like is not performed assuming possible combinations of GPS satellites. As shown in FIG. 2B, the recorder 33 obtains data (measured raw data) such as pseudo-range and orbit data of each GPS satellite obtained by the GPS receiver 32, IODE, and this measured raw data. The recorded time (measurement time), the GPS satellite (used satellite) from which the raw data was obtained, and the state of the signal from the GPS satellite (reception state) are recorded on the data file 35. Power supply 34
Is a power supply for supplying power to each part of the base station 3,
Unlike the batteries (14, 24, ...), there is no need to make them portable and transportable. The system of this embodiment is a post-analysis type system in which data files (15, 25,...) In which information is recorded by each mobile station (1, 2,...) Are later collected by the base station 3. Is done. FIG. 3 shows an operation flow of the processing device 36 executed using the collected data files (15, 25,...) And the recorded information on the data file 35. As shown in FIG. 1, in the present embodiment, the contents of the data files (15, 25,...) Collected at the time of analysis correction at the base station 3 are processed by the processing unit 36 in units of measurement time. (100). The processing device 36 reads information on the measurement time or the measurement time on which the interpolation (described later) is based from the data file 35 (102). Next, the processing device 36 determines whether or not the measured raw data is present on the data file 35 for three or four GPS satellites constituting the combination used by the mobile station at the measurement time (104). ).
If not, the processing device 36 reads information related to the next measurement time on the collected data files (15, 25,...) (108, 100). If there is no information to be read, the processing of the processing device 36 ends (1
06). G that constitutes the combination used by the mobile station
Raw data for PS satellites is data file 3
5, the processing device 36 performs a positioning operation using the measured raw data in the information read in step 102 to calculate the position of the own station (1).
10). In that case, by the IODE in the orbit data,
Confirm that the base station and the mobile station use orbit data with the same issue number (same issue time). The processing device 36
By subtracting the position obtained in step 110 from the known position of the base station 3, an error in the position obtained by calculation is obtained (112). The processing device 36 uses the obtained error as a correction amount, and adds this correction amount to the measurement position read in step 100 (114). The measurement positions thus obtained are stored on a data file (not shown) or supplied to another processing routine. When calculating the correction amount, the processing unit 36
Performs linear interpolation as needed. That is, as shown in FIG. 4, when calculating the correction amount of the position (latitude and longitude) for a measurement time other than the measurement time (Tn, etc.) recorded in the own station, the correction value is located before and after the measurement time. The correction amount corresponding to the measurement time recorded in the own station is linearly interpolated to obtain the correction amount. For this interpolation, the correction amount of the preceding and following measurement times is necessary, but this may be calculated and stored in advance, or may be calculated again when necessary. Is also good. As described above, in this embodiment, the mobile station (1, 2,...) Records the same information as the conventional position correction method, and the base station 3 records the same information as the conventional pseudo distance correction method. And a method that can be called a position / pseudo-distance correction method is realized. That is, in the present embodiment, the position of the base station 3 is obtained based on the measured raw data of the GPS satellites used in the mobile stations (1, 2,...)
The position correction calculation is performed based on the obtained position. Therefore,
The base station 3 does not need to perform position calculation on all combinations of GPS satellites that may be selected in the mobile station (1, 2,...), And performs measurement on all GPS satellites that may be selected. Since only raw data needs to be recorded, data processing performed at each measurement time can be simplified.
On the other hand, the mobile station (1, 2,...) Does not generally need to record the raw measurement data having a large data amount, but only has to record the measurement position, so that the data recording amount can be reduced. As a result, a system free from problems in terms of price and service can be realized. In this embodiment, the correction amount is interpolated at the time of position correction. Therefore, the data recording frequency in the base station 3 can be suppressed, and the data recording amount in the base station 3 can be reduced. Also, in general, the error of the measurement position does not change so sharply in time,
Even with such interpolation, sufficient practicality can be obtained. It should be noted that the present invention does not need to limit the recording form on the data file, nor does it need to limit what kind of media is used as the data file. As described above, according to the present invention,
The mobile station records the positioning satellite, position and measurement time, and the base station records the positioning satellite, orbit data, pseudorange and measurement time, and the base station records the position when correcting the position recorded by the mobile station. Based on the calculated orbit data and pseudo-range, the position, and thus the correction amount, is calculated, so that it is not necessary to perform position calculation for each combination of positioning satellites at the base station, and the data processing can be simplified. Since it is not necessary to record orbit data, measured raw data such as pseudoranges, and the amount of recorded data can be reduced, it is possible to realize a system free from problems in terms of price and service. According to the present invention, when correcting the position recorded by the mobile station, the correction amount is interpolated in the base station, so that the data recording frequency in the base station can be suppressed. And the amount of data recorded in the base station can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a system according to an embodiment of the present invention. FIG. 2 is a diagram showing the contents of data recorded in this embodiment. In particular, FIG.
(B) is a figure which shows each base station position record data. FIG. 3 is a flowchart showing an operation of the processing device of the base station in this embodiment. FIG. 4 is a diagram illustrating calculation of a correction amount in a base station and an interpolation straight line. 5A and 5B are diagrams showing the contents of data recorded in a conventional position correction method, in particular, FIG. 5A shows mobile station position recording data, and FIG. 5B shows base station position recording data. . FIGS. 6A and 6B are diagrams showing the contents of data recorded in the conventional pseudo-distance correction method, in particular, FIG. 6A shows mobile station position recording data, and FIG. 6B shows base station position recording data. is there. [Description of Signs] 1, 2 mobile station 3 base station 12, 22, 32 GPS receiver 13, 23, 33 recorder 15, 25, 35 data file 36 processor

Continuation of front page (56) References JP-A-61-196179 (JP, A) JP-A-62-272172 (JP, A) JP-A-4-354098 (JP, A) JP-A-5-107333 (JP) JP-A-6-3431 (JP, A) JP-A-6-3433 (JP, A) JP-A-6-18649 (JP, A) JP-A-5-130008 (JP, A) 62-144893 (JP, U) Earl G. BLACKWELL, Overview of Differential GPS Methods, GLOBAL POSITION ING SYSTEM Papers published in NAVIGATION VOLUME III, USA, 1984, ITU-T 88-100 Atsushi Tsuchiya, Tetsuro Imaburi, Guide to GPS Survey and Baseline Analysis, Japan, Japan Survey Association, October 26, 1992, first edition, pp. 127-130 RUDOLPH M.P. KALAFU S et al., Special Committee ee 104 Recommendations for Differential GPS Service, GLOBAL BAL POSITIONING SY STEM Papers, USA, USA, USA, USA, USA, USA, USA, USA, USA, USA, USA, USA, USA. 101-116 PETER LOOMIS, et al., Correction Algorithms for Differential GPS Reference States, GLOBAL POSITON ING SYSTEM IT publishing in the United States, USA, USA, USA. 91-105 (58) Field surveyed (Int. Cl. ⁷ , DB name) G01S 5/00-5/14

Claims (1)

(57) [Claims] [Claim 1] In a post-analysis satellite positioning system having a mobile station and a base station, which collects information recorded in the mobile station afterward and analyzes and corrects the information, Means for receiving signals from a predetermined number of positioning satellites selected from a plurality of positioning satellites, and measuring the position of the own station based on the received signals; selected positioning satellites, orbit data of the positioning satellites included in the received signal Means for recording information specifying the issue time of the above, the measured position and the measurement time for a series of measurement times, wherein the base station may be used by at least the mobile station among the plurality of positioning satellites Means for receiving orbit data from all positioning satellites as signals and measuring a pseudorange including an error based on a signal propagation time from the positioning satellite to the own station.
The measurement time interval recorded in the base station is
Longer than the measurement time interval recorded at
Data recording frequency is suppressed, and the base station receives the orbit data, the positioning satellite, the received orbit data,
Means for recording the measured pseudo-distance and the measurement time thereof, and a field of the measurement time which coincides with at least the measurement time recorded in the own station among the measurement times recorded in the mobile station.
In this case, the position of the own station is obtained based on the orbit data and the pseudorange of the positioning satellite selected by the mobile station, and the calculated position of the own station is compared with the known accurate position of the own station to correct the amount of correction.
And the measurement time not recorded in the own station is
If recorded at
Adjust the correction amount among the measurement times recorded in
Before and after the measurement time not recorded in the own station
Interpolation from the correction amounts obtained for multiple measurement times
And a means for correcting the position of the mobile station measured by the mobile station based on the obtained correction amount, and a post-analysis type satellite positioning system.