JP2014085204A - Precision positioning system, precision positioning device, and precision positioning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precision positioning system capable of minimizing a multi-path error in calculating an observation distance.SOLUTION: A precision positioning system includes a reference point Rs0 and plural observation points Rsa. A reference station performs: obtaining a reference point observation distance and a reference point calculation distance by using a GPS signal received at the reference point Rs0, so that an individual observation station obtains an observation point observation distance and observation point calculation distance by using a GPS signal received at each respective observation point Rsa (S101); calculating a double difference between the reference point Rs0 and the observation point Rsa (S102); calculating an average value of the calculated plural double differences (S103); and calculating a single difference in inter-satellite observation distance and adds the average value of the double difference, to correct the single difference in the inter-satellite observation distance so as to minimize a multi-path error (S104).

Description

  The present invention relates to a precision positioning system that sets a reference station and performs precise positioning using reference station information broadcast from the reference station.

  Conventionally, precise positioning using positioning signals such as GPS signals has been put to practical use in applications such as landslide detection. In such precise positioning, for example, as shown in Patent Document 1, a known reference station antenna whose position does not change is installed, and an observation station antenna is installed at a landslide observation point. The distance between the satellite and the observation point is measured from the positioning signal received by the observation station antenna, and a baseline vector between the reference point and the observation point is calculated. Then, the landslide is detected by detecting the change in the position of the observation point from the change in the baseline vector.

  One technique for such precise positioning is the RTK method (real-time kinematic method). In the RTK method, each observation station can perform its own positioning. At this time, each observation station performs positioning based on the reference station information.

  Here, the reference station information is generated based on the positioning result of the reference station, and includes the observation distance observed at the reference point (distance between the reference point and each satellite) and error information used for calculation of the observation distance.

  Each observation station can improve the positioning accuracy by calculating the observation distance using this reference station information.

JP 2004-144661 A

  Because the system is as described above, if the calculation accuracy of the observation distance of the reference station is improved, the positioning accuracy of the observation station will be improved. End up. Therefore, it is necessary to suppress errors included when calculating the observation distance of the reference station as much as possible. The error factors include ionospheric delay, tropospheric delay, satellite clock error, receiver clock error, and the like, which can be easily suppressed by a known method.

  In a situation where such an error factor can be suppressed, a multipath error that cannot be easily suppressed by the conventional method becomes a problem.

  An object of the present invention is to provide a precise positioning system capable of suppressing a multipath error when calculating an observation distance.

  The present invention calculates the first point observation distance using the carrier phase of positioning signals from a plurality of positioning satellites, and calculates the first point calculation distance using the position of the positioning satellite and the estimated own device position. The second station observation distance is calculated using the first station and the carrier phase of positioning signals from a plurality of positioning satellites, and the second point calculation distance is calculated using the position of the positioning satellite and the estimated position of the own device. The present invention relates to a precision positioning system including a plurality of second stations that are calculated respectively, and has the following characteristics.

  The first station, the second station or other station calculates a double difference deviation from the second point observation distance, the first point observation distance, the second point calculation distance, and the first point calculation distance, The average value of the double difference deviation with respect to the second station is calculated, and the calculation formula of the inter-satellite single phase difference based on the positioning signals from a plurality of positioning satellites is corrected using the average value of the double difference deviation.

  In this configuration, since the average value of the double difference deviation corresponds to the multipath error, the multipath error can be estimated and calculated. Then, by correcting the calculation formula of the inter-satellite single phase difference in the first station with the average value of the double difference deviation which is a multipath error, the calculation accuracy of the observation distance is improved, and highly accurate positioning auxiliary information Can be generated.

  In the precise positioning system of the present invention, the observation distance double difference is calculated from the second point observation distance and the first point observation distance, and the calculation distance double difference is calculated from the second point calculation distance and the first point calculation distance. And the difference of the double difference is calculated from the difference between the observed distance double difference and the calculated distance double difference.

  In the precise positioning system of the present invention, the first station generates and broadcasts positioning assistance information based on the result calculated by the single phase difference between satellites corrected by the average value of the double difference deviation. The second station performs positioning using the positioning assistance information.

  In this configuration, each second station performs positioning using highly accurate positioning auxiliary information. Thereby, the positioning accuracy of each second station is improved.

  In the precision positioning system of the present invention, positioning auxiliary information is generated and broadcast by at least one of the first station and the second station. The precision positioning system includes a third station that performs positioning using positioning auxiliary information and a positioning signal generated in at least one of the first station and the second station.

  With this configuration, it is possible to realize a precise positioning system that can broadcast positioning assistance information not only at the first station but also at the second station. At this time, each third station can use the positioning accuracy information with high accuracy as described above, so that the positioning accuracy of the third station is improved.

  The present invention also relates to a precision positioning device that performs positioning using positioning signals from a plurality of positioning satellites, and has the following characteristics. The precision positioning device calculates a first observation distance using a receiving unit that receives a positioning signal, and carrier wave phases of positioning signals from a plurality of positioning satellites, and determines the position of the positioning satellite and the estimated own device position. And a calculation unit that calculates the first point calculation distance and a wireless communication unit that receives the second point observation distance and the second point calculation distance at a second point different from the first point from the outside. The calculation unit calculates the double difference deviation from the second point observation distance, the first point observation distance, the second point calculation distance, and the first point calculation distance, and averages the double difference deviation for a plurality of second stations. A value is calculated, and a formula for calculating a single phase difference between satellites based on positioning signals from a plurality of positioning satellites is corrected using an average value of double difference deviation.

  In this configuration, since the average value of the double difference deviation corresponds to the multipath error, the multipath error can be estimated and calculated.

  According to the present invention, it is possible to sufficiently suppress the multipath error included in the observation distance of the reference station and generate highly accurate reference station information (positioning auxiliary information).

It is a schematic block diagram of the precise positioning system of this invention. It is a block diagram which shows the structure of the reference | standard station 100 and the observation station 110 of the precise positioning system of this invention. It is a flowchart which shows the processing flow of the precise positioning method of this invention.

  A precision positioning system and a precision positioning method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a precision positioning system of the present invention. FIG. 2 is a block diagram showing the configuration of the reference station 100 and the observation station 110 of the precision positioning system of the present invention. Note that FIG. 2 illustrates only the observation station 110 at the observation point Rs1, but the other observation points Rs2 and Rs3 also include observation stations having the same configuration as the observation station 101. The reference station 100 corresponds to the “first station” of the present invention, and the observation station 110 corresponds to the “second station” of the present invention.

  In the present embodiment, the case where precise positioning is performed by the RTK method (real kinematic method) using a GPS signal is shown. However, the present invention is not limited to the GPS signal, and the configuration and method of the present invention can be applied when using other positioning signals.

  The precision positioning system of the present invention includes a GPS antenna ANT0 installed at a reference point Rs, a GPS antenna ANT1 installed at an observation point Rs1, a GPS antenna ANT2 installed at an observation point Rs2, and a GPS antenna installed at an observation point Rs3. ANT3 is provided. Note that the number of observation points is not limited to this, but may be two or more, and a larger number of observation points is preferable. The reference point corresponds to the “first point” of the present invention, and the observation point corresponds to the “second point” of the present invention.

  The precise positioning system of the present invention includes GPS satellites Sat0, Sat1, Sat2, and Sat3 that can be simultaneously observed by the GPS antennas ANT0, ANT1, ANT2, and ANT3. The number of GPS satellites that can be observed simultaneously may be other numbers as long as it is four or more.

  Each GPS satellite Sat0, Sat1, Sat2, Sat3 broadcasts a GPS signal composed of a carrier wave of the same frequency in synchronization with the GPS time. The GPS signal is a signal that is code-modulated with a unique code that differs for each of the GPS satellites Sat0, Sat1, Sat2, and Sat3.

  As shown in FIG. 2, the reference station 100 includes a GPS antenna ANT0, and also includes a GPS receiving unit 101, a calculation unit 102, a wireless communication unit 103, and a wireless communication antenna DANT0.

  The GPS receiving unit 101 captures and tracks the code phase and carrier phase (carrier phase) of the GPS signal received by the GPS antenna ANT0, and sequentially outputs tracking results such as a code phase difference and a carrier phase difference to the calculation unit 102.

  The computing unit 102 calculates the reference point observation distance from the carrier phase difference. The computing unit 102 demodulates the GPS signal and obtains a navigation message. The calculation unit 102 calculates the reference point calculation distance from the satellite orbit information included in the navigation message and the positioning result based on the reference point observation distance calculated previously.

  The calculation unit 102 stores the position of the reference station 100 (reference point Rs0) in advance, and calculates a positioning error between the observation position obtained from the reference point observation distance and the reference point position. At this time, the calculation unit 102 calculates a positioning error in a state where the multipath error is suppressed using a method described later. The calculation unit 102 generates reference station information (positioning auxiliary information) from this positioning error and other positioning related information, and outputs it to the wireless communication unit 103.

  The wireless communication unit 103 converts the reference station information into a wireless communication format and broadcasts it from the wireless communication antenna DANT0.

  Further, the wireless communication unit 103 receives observation station information including an observation distance (observation point observation distance) and a calculation distance (observation point calculation distance) from each observation station by the wireless communication antenna DANT0, and receives the observation station information. Is demodulated and output to the calculation unit 102.

  The calculation unit 102 performs the above-described multipath error suppression calculation using the observation point observation distance and observation point calculation distance of each observation station included in the observation station information.

  The observation station 101 includes a GPS antenna ANT1, and also includes a GPS receiving unit 111, a calculation unit 112, a wireless communication unit 113, and a wireless communication antenna DANT1.

  The GPS receiving unit 111 captures and tracks the code phase and carrier phase (carrier phase) of the GPS signal received by the GPS antenna ANT1, and sequentially outputs tracking results such as a code phase difference and a carrier phase difference to the calculation unit 112.

  The calculation unit 112 calculates the observation point observation distance from the carrier phase difference. The computing unit 112 demodulates the GPS signal and obtains a navigation message. The calculation unit 112 calculates the observation point calculation distance from the satellite orbit information included in the navigation message and the positioning result based on the observation point observation distance calculated previously.

  The calculation unit 112 generates observation station information including the observation point observation distance and the observation point calculation distance, and outputs the observation station information to the wireless communication unit 113.

  The wireless communication unit 113 converts the observation station information into a wireless communication format and broadcasts it from the wireless communication antenna DANT1.

  Further, the wireless communication unit 113 receives the reference station information from the reference station by the wireless communication antenna DANT1, demodulates the reference station information, and outputs the demodulated information to the calculation unit 112.

  The calculation unit 112 performs positioning using the reference station information.

  Note that the observation stations at the other observation points Rs2 and Rs3 perform the same processing as the observation station 101.

  In such a precise positioning system, multipath errors in the reference station 100 are suppressed based on the following principle.

As shown in FIG. 1, the true distance between the GPS satellite Sat0 and the reference point Rs0 is _Ds0r0 . Let D _s1r0 be the true distance between the GPS satellite Sat1 and the reference point Rs0. The true distance of the GPS satellites Sat0 and observation point Rs1 and _{D s0r1.} Let D _s1r1 be the true distance between the GPS satellite Sat1 and the observation point Rs1.

In this case, the single-satellite single difference at the reference point Rs0 is ( _{Ds1r0− Ds0r0} ). The single difference between the satellites at the observation point Rs1 is (D _s1r1 −D _s0r1 ).

  Therefore, the double difference between the reference point Rs0, the observation point Rs1, and the GPS satellites Sat0 and Sat1 is expressed by the following formula 1.

_{W s1r1 = (D s1r1 -D s0r1} ) - (D s1r0 -D s0r0) - ( Equation 1)
The reference point observation distance between the GPS satellite Sat0 and the reference point Rs0 is _Ms0r0 . The reference point observation distance between the GPS satellite Sat1 and the reference point Rs0 is _Ms1r0 . The observation point observation distance between the GPS satellite Sat0 and the observation point Rs1 is _Ms0r1 . The observation point observation distance between the GPS satellite Sat1 and the observation point Rs1 is _Ms1r1 .

From Expression 1, the double difference MW _s1r1 of the observation distance by the reference point Rs0, the observation point Rs1, and the GPS satellites Sat0 and Sat1 is expressed by the following Expression 2.

MW _s1r1 = (M _s1r1 -M _s0r1 )-(M _s1r0 -M _s0r0 )-(Formula 2)
Further, the reference point calculation distance between the GPS satellite Sat0 and the reference point Rs0 is _Cs0r0 . The reference point calculation distance between the GPS satellite Sat1 and the reference point Rs0 is _Cs1r0 . The observation point calculation distance between the GPS satellite Sat0 and the observation point Rs1 is _Cs0r1 . The observation point calculation distance between the GPS satellite Sat1 and the observation point Rs1 is _Cs1r1 .

From Expression 1, the double difference CW _s1r1 of the calculation distance by the reference point Rs0, the observation point Rs1, and the GPS satellites Sat0 and Sat1 is expressed by the following Expression 3.

CW _s1r1 = (C _s1r1 -C _s0r1 )-(C _s1r0 -C _s0r0 )-(Formula 3)
Double difference deviation _{A S1r1} is because the difference between the observed distance of the double difference _{MW S1r1} and calculated distance of the double difference _{CW S1r1,} the following equation 4.

  When this is transformed, the following equation 5 is obtained.

Here, the GPS satellites SAT0 at an observation point Rs1, Sat1 the by-synthesis multipath error and _{P 01,} the inter-satellite clock error and _{CB 01,} the sum of these errors are observed by GPS satellites SAT0, Sat1 at an observation point Rs1 This corresponds to the difference between the single difference in distance between satellites and the single difference in calculation distance between satellites. Therefore, the following expression 6 is established.

Similarly, when the composite multipath errors of the GPS satellites SAT0, Sat1 at the reference point Rs0 and _{P 01,} the inter-satellite clock error from being a _{CB 01,} the sum of these errors, the GPS satellites at the reference point Rs0 SAT0, This corresponds to the difference between the single difference between satellites in the observation distance by Sat1 and the single difference between satellites in the calculation distance. Therefore, the following expression 7 is established.

By substituting Equations 6 and 7 into Equation 5, the double difference deviation A _s1r1 is expressed by the following equation.

That is, the double difference deviation A _s1r1 is a difference (P ₁₀ −P ₁₁ ) of the combined multipath error.

When such a double difference deviation is performed for each observation point, the double difference deviation A _s1ra between the reference station Rs0, the observation point Rsa, and the GPS satellites Sat0 and _Sat1 is the difference between the combined multipath errors (P ₁₀ −P _1a )

Multipath has a low correlation even if the observation point is different by about 1 m. Therefore, when the double difference deviation A _s1ra for each observation point is added, the combined multipath error P _1a for the observation point becomes approximately zero. Thus, the average value by adding the double difference deviation _{A S1ra} for each observation point, a negative value of the composite multipath error _{P 10} relative to the reference point Rs0 a _{(-P 10).}

  At the reference point Rs0, the following observation equation is established with the GPS satellite Sat0.

Here, Φ _s0r0 is an observation distance between the reference point Rs0 obtained from the carrier phase difference and the GPS satellite Sat0. D _s0r0 is a true distance between the reference point Rs0 obtained from the carrier phase difference and the GPS satellite Sat0. ΔI _r0 is the ionospheric delay amount at the reference point Rs0, and ΔT _r0 is the tropospheric delay amount at the reference point Rs0. Further, ε _s0 is a satellite clock error of the GPS satellite Sat0, and ε _r0 is a receiver clock error of the reference station 100 at the reference point Rs0. N _s0r0 is an integer bias between the reference point Rs0 and the GPS satellite Sat0. ΔP _s0r0 is a multipath error of the GPS positioning signal from the GPS satellite Sat0 at the reference point Rs0. f is the frequency of the carrier wave, and λ is the wavelength of the carrier wave.

  At the reference point Rs0, the following observation equation is established with the GPS satellite Sat1.

Here, Φ _s1r0 is an observation distance between the reference point Rs0 obtained from the carrier phase difference and the GPS satellite Sat1. D _s1r0 is a true distance between the reference point Rs0 obtained from the carrier phase difference and the GPS satellite Sat1. ΔI _r0 is the ionospheric delay amount at the reference point Rs0, and ΔT _r0 is the tropospheric delay amount at the reference point Rs0. Further, ε _s1 is a satellite clock error of the GPS satellite Sat1, and ε _r0 is a receiver clock error of the reference station 100 at the reference point Rs0. N _s1r0 is an integer bias between the reference point Rs0 and the GPS satellite Sat1. ΔP _s1r0 is a multipath error of the GPS positioning signal from the GPS satellite Sat1 at the reference point Rs0.

  Therefore, the single difference of the observation distances of the GPS satellites Sat1 and Sat0 at the reference point Rs0 is expressed by the following equation (11).

In Expression 10, (ΔP _s0r0 −ΔP _s1r0 ) subtracts the multipath error of the GPS positioning signal of the GPS satellite Sat1 at the reference point Rs0 from the multipath error of the GPS positioning signal of the GPS satellite Sat0 at the reference point Rs0. Therefore, this corresponds to a combined multipath error caused by the reference point Rs0 and the GPS satellites Sat0 and Sat1.

  Therefore, the multipath error included in the single difference between the satellites in the observation distance of the GPS satellites Sat1 and Sat0 at the reference point Rs0 can be determined by the double difference deviation.

As a result, by adding and correcting the composite multipath error (−P ₁₀ ) calculated by the double difference deviation A _{s1r1 to} both sides of Equation 10, the single difference between the satellites of the observation distance in which the multipath error is suppressed is corrected. Can be calculated.

By using the inter-satellite single differences [Phi _C after the correction to the reference station information, it is possible to generate a more accurate reference station information. By using such highly accurate reference station information, each observation station can calculate and measure a highly accurate baseline vector.

In addition, although the satellite clock error is included in the above-described single difference Φ _C between the satellites, these satellites are calculated by calculating the observation distance double difference between each observation station, the base station, and each GPS satellite. The clock error is offset and does not affect the positioning result of the observation station. Therefore, each observation station can perform calculation of a highly accurate baseline vector, calculation of a highly accurate baseline vector, and positioning.

  Conventionally, it has been necessary to consider the shape and installation position of the antenna so that it is not easily affected by multipaths. However, by using the configuration of this embodiment, it is not necessary to take these considerations into account. Points and observation points can be installed without restrictions. Furthermore, since the shape of the antenna can be simplified, high-accuracy positioning can be performed with an easy and inexpensive antenna.

  In the above description, the case where multipath error suppression processing is performed in each functional block is shown. However, a program as shown in FIG. 3 is stored in the computer installed in the base station and the computer installed in the observation station. Precise positioning may be realized by storing and executing this program. FIG. 3 is a flowchart showing a processing flow of the precise positioning method of the present invention.

  First, an observation distance and a calculation distance are acquired at a reference point Rs0 and a plurality of observation points Rsa (a according to the number of observation points is a positive integer) (S101). The observation distance of the reference point Rs0 (reference point observation distance) and the calculation distance (reference point calculation distance) are acquired by a reference station connected to the GPS antenna of the reference point Rs0. The Rsa observation distance (observation point observation distance) and the calculation distance (observation point calculation distance) of each observation point are acquired by an observation station connected to the GPS antenna of each observation point.

  Next, a double difference deviation between the reference point Rs0 and the observation point Rsa is calculated (S102). This double difference deviation is calculated for each observation point. This process is executed by the reference station. The method of calculating the double difference deviation is to calculate the difference between the observation distance of the reference point and the observation distance of the reference point and the difference between the calculation distance of the reference point and the calculation distance of the observation point, and further add these differences. A method may be used, and a difference between the observation distance and the calculation distance of the reference point and a difference between the observation distance and the calculation distance of the observation point may be calculated, and the difference may be further added.

  Next, an average value of the plurality of calculated double difference deviations is calculated (S103). This process is also executed by the reference station.

  Next, a single difference between the satellite observation distances is calculated and corrected by adding the average value of the double difference deviation (S104). As a result, it is possible to obtain a highly accurate single difference between the satellite observation distances closer to the true distance while suppressing the influence of the multipath error included in the single difference between the satellite observation distances.

  Then, reference station information is generated from the single difference between the corrected inter-satellite observation distances. By performing such processing, it is possible to generate and broadcast highly accurate reference station information in which multipath errors of the reference station are suppressed.

  Note that such multipath error suppression calculation may be performed by a control center or the like separate from the reference station and the observation station.

  In the above description, the reference station information from the reference station is received by each observation station and used for positioning, for example, a landslide detection system. However, the landslide detection system detects that the observation point is not moving, and the position is fixed and does not fluctuate in the same manner as the reference point.

  Therefore, it is also possible to execute the reference station information generation process in which the multipath error is suppressed at each observation station. By performing such processing, each observation station can be used as a new second reference station.

  For example, a second observation station (corresponding to the “third station” of the present invention) different from these observation stations whose positions are fixed is set, and the reference station or each observation station (second reference station) is set. When the second observation station receives and uses the reference station information, the second observation station can perform highly accurate positioning.

100: reference station,
101, 111: GPS receiver,
102, 112: arithmetic unit,
103, 113: wireless communication unit,
110: Observation station,
ANT0, ANT1, ANT2, ANT3: GPS antenna,
Rs0: reference point,
Rs1, Rs2, Rs3: observation points,
Sat0, Sat1, Sat2, Sat3: GPS satellites,
DANT0, DANT1: Wireless communication antenna

Claims (6)

A first station that calculates a first point observation distance using the carrier phase of positioning signals from a plurality of positioning satellites, and calculates a first point calculation distance using the position of the positioning satellite and the estimated own device position When,
The second point observation distance is calculated using the carrier phase of the positioning signals from a plurality of positioning satellites, and the second point calculation distance is calculated using the position of the positioning satellite and the estimated own device position, respectively. A second station,
A precision positioning system comprising:
A double difference deviation is calculated from the second point observation distance, the first point observation distance, the second point calculation distance, and the first point calculation distance;
Calculating an average value of the double difference deviation for a plurality of second stations;
Using the average value of the double difference deviation, to correct the calculation formula of the inter-satellite single phase difference by the positioning signals from the plurality of positioning satellites,
Precision positioning system. The precision positioning system according to claim 1,
Calculate the observation distance double difference from the second point observation distance and the first point observation distance,
Calculate the calculated distance double difference from the second point calculated distance and the first point calculated distance,
A precision positioning system that calculates a deviation of the double difference from a difference between the observation distance double difference and the calculated distance double difference. The precision positioning system according to claim 1 or claim 2,
The first station is
Based on the result calculated by the single phase difference between the satellites corrected with the average value of the double difference deviation, generate and broadcast positioning auxiliary information,
The second station is
Perform positioning using the positioning auxiliary information,
Precision positioning system. The precision positioning system according to claim 2,
Generating and broadcasting the positioning assistance information in at least one of the first station and the second station;
A third station that performs positioning using the positioning auxiliary information generated by at least one of the first station and the second station and the positioning signal;
Precision positioning system. A precision positioning device that performs positioning using positioning signals from a plurality of positioning satellites,
A receiver for receiving the positioning signal;
A calculation unit that calculates the first point observation distance using the carrier phase of the positioning signals from the plurality of positioning satellites, and calculates the first point calculation distance using the position of the positioning satellite and the estimated own device position;
A wireless communication unit for receiving a second point observation distance and a second point calculation distance at a second point different from the first point from the outside,
The computing unit is
A double difference deviation is calculated from the second point observation distance, the first point observation distance, the second point calculation distance, and the first point calculation distance;
Calculating an average value of the double difference deviation for a plurality of second stations;
Using the average value of the double difference deviation, to correct the calculation formula of the inter-satellite single phase difference by the positioning signals from the plurality of positioning satellites,
Precision positioning device. The first point observation distance is calculated using the carrier phase of the positioning signals from the plurality of positioning satellites in the first station, and the first point calculation distance is calculated using the position of the positioning satellite and the estimated device position. And a process of
A second point observation distance is calculated using the carrier phase of positioning signals from a plurality of positioning satellites in a plurality of second stations, and the second point calculation distance using the position of the positioning satellite and the estimated device position. Calculating
Calculating a double difference deviation from the second point observation distance, the first point observation distance, the second point calculation distance, and the first point calculation distance;
Calculating an average value of the double difference deviation for a plurality of second stations;
Using a mean value of the double difference deviation, correcting a calculation formula of a single phase difference between satellites by positioning signals from the plurality of positioning satellites,
Precision positioning method.

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