Patent Description:
For satellite positioning, there is a positioning technique of obtaining an accurate positioning solution by correcting errors contained in a ranging signal transmitted by a positioning satellite by means of positioning augmentation information (hereinafter denoted as augmentation information) and solving an integer value bias which is uncertainty of carrier phase. Augmentation information as error information is provided as a quantity of state corresponding to each error factor, and techniques for independently performing accurate positioning using error information include PPP-AR (Precise Point Positioning Ambiguity Resolution) and PPP-RTK (Precise Point Positioning Real-Time Kinematic). In the PPP-AR positioning approach, a positioning apparatus of a user acquires information on satellite orbit error, satellite clock error, and satellite signal bias, and corrects errors contained in ranging signals. Since satellite signal bias as error information differs from signal type to signal type, such as L1C/A, L2P, and L2C, they are provided to the positioning apparatus of the user for each signal type.

In the PPP-AR, for tropospheric delay and ionospheric delay, correction with a model is performed or they are estimated and removed by an estimation filter such as a Kalman filter. In the PPP-RTK positioning approach, error information related to tropospheric delay and ionospheric delay is provided in addition to satellite orbit error, satellite clock error, and satellite signal bias, and the positioning apparatus of the user can correct errors contained in ranging signals from such error information (Patent Literature <NUM>, for instance). An approach to provide a positioning device capable of solving a problem in conventional GNSS receivers that the flexibility is insufficient regarding use of reinforcement signal is known (Patent Document <NUM>, for instance). Herein, the troposphere error, the ionospheric error, and the satellite clock error and the satellite orbit error are used to calculate a carrier phase correction value and a pseudo range correction value. If these pieces of information are not available, it is not possible to calculate the correction values. A device to generate positioning augmentation information for isolated islands, which are regions where a service may not be received due to regional remoteness from a service range of a reference station network, without influencing positioning augmentation information for the service range when the positioning augmentation information for the isolated islands is distributed to the isolated islands is also known (Patent Document <NUM>, for instance).

Augmentation information includes error information that is different from one ranging signal to another; only when the signal type of a ranging signal received by the positioning apparatus of the user matches the signal type of error information contained in augmentation information, errors contained in the ranging signal can be corrected with the error information contained in the augmentation information.

In other words, some of multiple pieces of error information contained in augmentation information cannot be used for correction of errors contained in a ranging signal unless they match the signal type of the ranging signal, and error information could be unusable for correction of errors contained in a ranging signal depending on difference in signal type.

As mentioned above, when the signal type of a ranging signal and the signal type of error information do not match, error correction cannot be performed on the ranging signal and thus the ranging signal cannot be used in positioning calculation, which leads to an issue of lowered positioning accuracy.

The present disclosure aims to provide apparatuses for converting error information to error information of a usable signal type when the signal type of a ranging signal and the signal type of the error information do not match.

The technical problem is solved by the subject-matter of the independent claims. The dependent claims describe further preferred embodiments, and this description explains how the present invention may be carried out.

As the present disclosure enables error correction on a ranging signal when the signal type of the ranging signal and the signal type of error information do not match, use of the ranging signal in positioning calculation becomes possible and reduction in positioning accuracy can be suppressed.

A positioning apparatus <NUM> in Embodiment <NUM> is described below with reference to drawings.

The positioning apparatus <NUM> performs positioning using the PPP-RTK positioning approach. A feature of the positioning apparatus <NUM> is that it has a function of converting error information to a signal type that is applicable to a ranging signal in question when the signal type of a ranging signal transmitted by a positioning satellite does not match the signal type of error information contained in augmentation information, like a signal bias related to pseudorange or a signal bias related to carrier phase, and the error information cannot be applied to the ranging signal.

<FIG> is a diagram illustrating error factors in positioning using ranging signals. Ranging signals transmitted by positioning satellites that constitute a GNSS (Global Navigation Satellite System), such as a GPS satellite <NUM>, a Galileo satellite <NUM>, and a quasi-zenith satellite <NUM>, have orbit error, satellite clock error, and satellite signal bias as errors originating from positioning satellites. In the embodiments below, satellite signal bias will be divided into signal bias related to pseudorange and signal bias related to carrier phase in description. Signal bias related to pseudorange is denoted as CB and signal bias related to carrier phase is denoted as PB. In <FIG>, the signal bias CB related to pseudorange and the signal bias PB related to carrier phase are shown with a ranging signal L1 of the GPS satellite <NUM> and a ranging signal E1b of the Galileo satellite <NUM>.

Errors originating from a propagation channel of a ranging signal include ionospheric propagation delay error and tropospheric propagation delay error (hereinafter denoted as ionospheric error and tropospheric error). Errors originating from a reception circuit of the positioning apparatus <NUM> include receiver clock error, receiver noise, and also multipath caused by interference between a ranging signal reflected on a building and a ranging signal received directly from a positioning satellite.

When positioning is performed using augmentation information provided in a state space representation (SSR), error correction cannot be performed on a ranging signal that does not match the signal type of a satellite signal bias contained in augmentation information, so that the ranging signal cannot be used in positioning calculation.

<FIG> is a diagram explaining that augmentation information cannot be used with a ranging signal of a different signal type. <FIG> shows the following. The GPS satellite <NUM> transmits a transmission signal 311a.

The transmission signal 311a includes ranging signals L1C/A and L2C, which are of multiple signal types with different frequencies. The Galileo satellite <NUM> transmits a transmission signal 312a. The transmission signal 312a includes ranging signals E1b, E5a, and E5b, which are of multiple signal types with different frequencies. The quasi-zenith satellite <NUM> transmits a transmission signal 313a. The transmission signal 313a includes ranging signals L1C/A and L2C, which are of multiple signal types with different frequencies, and augmentation information [L6]. The symbol [ ] indicates being error information. The augmentation information [L6] may be information adherent to SSR compression format (Compact SSR) corresponding to the PPP-RTK positioning, capable of positioning on the order of centimeters, as a state space representation.

For the GPS satellite <NUM>, the augmentation information [L6] includes error information [L1C/A] and error information [L2C] respectively compatible with the respective signal types of ranging signals. For the quasi-zenith satellite <NUM>, the augmentation information [L6] includes error information [L1C/A] and error information [L2C] respectively compatible with the respective signal types of ranging signals. For the Galileo satellite <NUM>, the augmentation information [L6] includes error information [E1b] and [E5a] respectively compatible with the respective signal types of the ranging signals E1b and E5a. However, the augmentation information [L6] does not include error information [E5b] compatible with the signal type of the ranging signal E5b.

The positioning apparatus <NUM> accordingly converts the error information [E5a] of a signal type not compatible with the ranging signal E5b to error information [E5b] compatible with the ranging signal E5b. The positioning apparatus <NUM> uses the error information [E5b] converted from the error information [E5a] to correct errors contained in the ranging signal E5b.

<FIG> shows features of the positioning apparatus <NUM>. With reference to <FIG>, conversion of the error information [E5a] to the error information [E5b] by the positioning apparatus <NUM> is described. The error information is the signal bias PB related to carrier phase and the signal bias CB related to pseudorange. Error information before conversion is indicated by the suffix "i" and error information after conversion is indicated by the suffix "j". That is, error information before conversion is a signal bias PBi related to carrier phase and a signal bias CBi related to pseudorange, and error information after conversion is a signal bias PBj related to carrier phase and a signal bias CBj related to pseudorange. In the following, the signal bias PBj related to carrier phase and signal bias CBj related to pseudorange may be denoted as signal bias PBj and signal bias CBj. As shown in <FIG>, the quasi-zenith satellite <NUM> is transmitting augmentation information [L6] including error information [E5a].

The way of computing the conversion formula F(λi, λj, CBi, PBi) is described. The expression (<NUM>) below shows the conversion formula F(λi, λj, CBi, PBi) specifically. In expression (<NUM>), the signal bias PBj after conversion is denoted as PBj bar, with a line above. The signal bias PBi is error information for the ranging signal E5a and the signal bias PBj is error information for the ranging signal E5b. FORMULA <NUM> <MAT>.

Expressions (<NUM>) to (<NUM>) below are observation equations relating to ranging signals of the frequency fi and the frequency fj. A ranging signal of the frequency fi corresponds to the ranging signal E5a of the Galileo satellite <NUM>. A ranging signal of the frequency fj corresponds to the ranging signal E5b of the Galileo satellite <NUM>.

Eliminating the geometric distance ρ through expressions (<NUM>) to (<NUM>) yields expressions (<NUM>) and (<NUM>): <MAT>.

The portion enclosed by a broken line in expression (<NUM>) is known to take a particular value regardless of satellite and time. It can also be freely set at any value because it will be canceled at a position calculation unit 29a, discussed later. Thus, it is assumed as zero here. The expression enclosed by a broken line in expression (<NUM>), "δPj - δPi", is also known to take a particular value regardless of time. Thus, the portion enclosed by a broken line in expression (<NUM>) can be denoted as expression (<NUM>-<NUM>). In expression (<NUM>-<NUM>), Const = <NUM> holds. Expression (<NUM>-<NUM>) is further turned into expression (<NUM>-<NUM>). The portion enclosed by a broken line in expression (<NUM>) can be denoted as expression (<NUM>-<NUM>) and further as expression (<NUM>-<NUM>). <MAT> δφ and δP are read as Phase Bias and Code bias for a CLAS correction amount.

For the ranging signal of a frequency fk, δφk × λk = PBk and δPk = CBk hold. That is, using expressions (<NUM>-<NUM>) and (<NUM>-<NUM>) above, expressions (<NUM>-<NUM>) and (<NUM>-<NUM>) can be derived. In expression (<NUM>-<NUM>), setting Const = <NUM> can yield expression (<NUM>). In expression (<NUM>-<NUM>), for the speed of light c, c = fλ and c = fi × λi = fj × λj hold. The PBj hat in expression (<NUM>-<NUM>) is the PBj bar in expression (<NUM>).

For expression (<NUM>-<NUM>), by setting Const = Δp, it can be denoted as expression (<NUM>):
FORMULA <NUM> <MAT>.

<FIG> shows the conversion table <NUM>. As discussed later, a second bias conversion unit <NUM> of the positioning apparatus <NUM> converts CBi to CBj by making reference to the conversion table <NUM>. The conversion table <NUM> is described. For the signal bias CB related to pseudorange, a conversion value Δp for use in conversion is prepared on a per-satellite basis because the signal bias CB related to pseudorange has small variations with time. The second bias conversion unit <NUM> reads Δp and converts CBi to CBj according to expression <NUM>. The satellite number in the conversion table <NUM> is indicative of the type of the Galileo satellite <NUM>. Signal type before conversion refers to the pseudorange signal bias CBi before conversion. Signal type after conversion refers to the pseudorange signal bias CBj after conversion. The conversion value Δp is Δp in expression (<NUM>).

As mentioned in the description of <FIG>, a conversion unit converts first augmentation information PBi for correcting the carrier phase, which is first calculation information for position calculation contained in a first ranging signal E5a having a first frequency, to second augmentation information PBj for correcting the carrier phase, which is second calculation information for position calculation contained in a second ranging signal E5b having a second frequency, based on a first wavelength λi and a second wavelength λj, as shown in expression (<NUM>). A first correction unit <NUM>, discussed later, corrects φj, or the second calculation information, according to expression (<NUM>) discussed later using the second augmentation information PBj converted from the first augmentation information PBi.

For expression (<NUM>), the first calculation information is the carrier phase contained in the first ranging signal E5a as shown above. The second calculation information is the carrier phase contained in the second ranging signal E5b.

The first augmentation information is a signal bias for correcting the carrier phase contained in the first ranging signal E5a. The second augmentation information is a signal bias for correcting the carrier phase contained in the second ranging signal E5b. A first bias conversion unit <NUM>, discussed later, converts the first augmentation information PBi to the second augmentation information PBj based on an expression of linear combination of the signal bias PBi related to carrier phase as the first augmentation information contained in the first ranging signal E5a and the signal bias CBi related to pseudorange as information for correcting a pseudorange contained in the first ranging signal E5a, as shown in expression (<NUM>).

Conversion of the signal bias CBi related to pseudorange using the conversion table <NUM> of <FIG> is done in the following manner. As mentioned in the description of <FIG>, the conversion unit converts the first augmentation information CBi for correcting a pseudorange, which is the first calculation information for position calculation contained in the first ranging signal E5a having the first frequency, to the second augmentation information CBj for correcting a pseudorange, which is the second calculation information for position calculation contained in the second ranging signal E5b having the second frequency, based on a first wavelength λi and a second wavelength λj, as shown in expression (<NUM>). A second correction unit <NUM>, discussed later, corrects Pj, or the second calculation information, according to expression (<NUM>) discussed later using the second augmentation information CBj converted from the first augmentation information CBi.

For expression (<NUM>), the first calculation information is the pseudorange contained in the first ranging signal E5a as shown above. The second calculation information is the pseudorange contained in the second ranging signal E5b. The first augmentation information is the signal bias CBi for correcting the pseudorange contained in the first ranging signal E5a. The second augmentation information is the signal bias CBj for correcting the pseudorange contained in the second ranging signal E5b. The second bias conversion unit <NUM> converts the first augmentation information CBi to the second augmentation information CBj by making reference to the conversion table <NUM>, which is conversion information indicating values Δp for use in conversion to the second augmentation information CBj, as mentioned in the description of <FIG>.

<FIG> is a hardware configuration diagram of the positioning apparatus <NUM>. The positioning apparatus <NUM> includes a GNSS reception unit <NUM>, a processor <NUM>, a main storage device <NUM>, and an auxiliary storage device <NUM> as hardware. The pieces of hardware are connected by a signal line <NUM>.

The GNSS reception unit <NUM> includes an antenna <NUM>, a splitter <NUM>, a ranging signal reception unit <NUM>, and an augmentation information reception unit <NUM>. The antenna <NUM> receives the transmission signal 311a, the transmission signal 312a, and the transmission signal 313a from the GPS satellite <NUM>, the Galileo satellite <NUM>, and the quasi-zenith satellite <NUM>. The splitter <NUM> distributes the signals received by the antenna <NUM> to the ranging signal reception unit <NUM> and the augmentation information reception unit <NUM>. The ranging signal reception unit <NUM> sends ranging signals to a satellite calculation unit <NUM> and a first decoding unit <NUM> out of the signals distributed from the splitter <NUM>. The ranging signal reception unit <NUM> sends carrier phase φ, pseudorange P, and Doppler D to the first decoding unit <NUM>, and navigation messages to the satellite calculation unit <NUM>. The augmentation information reception unit <NUM> sends augmentation information to a second decoding unit <NUM> out of the signals distributed from the splitter <NUM>.

The processor <NUM> includes the satellite calculation unit <NUM>, the first decoding unit <NUM>, the second decoding unit <NUM>, a satellite correction unit <NUM>, a delay calculation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, the first correction unit <NUM>, the second correction unit <NUM>, and the position calculation unit 29a. These functional components are implemented by a program. The program is stored in the auxiliary storage device <NUM>. The functions of the respective components will be described later in Description of operation. The first bias conversion unit <NUM> and the second bias conversion unit <NUM> are the conversion unit. The first correction unit <NUM> and the second correction unit <NUM> are a correction unit.

The auxiliary storage device <NUM> stores the conversion table <NUM> and various types of data, not shown. The processor <NUM> loads data in the auxiliary storage device <NUM> into the main storage device <NUM> and reads the data from the main storage device <NUM>.

The GNSS reception unit <NUM> receives navigation messages, augmentation information, carrier phase, pseudorange, and Doppler. It receives transmission signals transmitted by positioning satellites. Transmission signals from the GPS satellite <NUM> and the Galileo satellite <NUM> include navigation messages and ranging signals. Transmission signals from the quasi-zenith satellite <NUM> include augmentation information as well as navigation messages and ranging signals. A ranging signal contains carrier phase, pseudorange, and Doppler.

<FIG> is a flowchart illustrating the operation of the positioning apparatus <NUM>. Referring to <FIG>, the operation of the positioning apparatus <NUM> is described. The GNSS reception unit <NUM> receives signals transmitted by the GPS satellite <NUM>, the Galileo satellite <NUM>, and the quasi-zenith satellite <NUM> via the antenna <NUM>. The splitter <NUM> distributes signals received from the satellites. The splitter <NUM> sends ranging signals from the GPS satellite <NUM>, the Galileo satellite <NUM>, and the quasi-zenith satellite <NUM> to the ranging signal reception unit <NUM>, and augmentation information received from the quasi-zenith satellite <NUM> to the augmentation information reception unit <NUM>. The ranging signal reception unit <NUM> sends the carrier phase, the pseudorange, and Doppler contained in ranging signals to the first decoding unit <NUM>. The augmentation information reception unit <NUM> sends augmentation information to the satellite correction unit <NUM>, the delay calculation unit <NUM>, the first bias conversion unit <NUM>, and the second bias conversion unit <NUM>.

At step S111, the first decoding unit <NUM> decodes a ranging signal. The first decoding unit <NUM> decodes the ranging signal and sends the pseudorange P to the second correction unit <NUM>, the carrier phase φ to the first correction unit <NUM>, and Doppler shift to the position calculation unit 29a.

At step S112, the second decoding unit <NUM> decodes augmentation information. The second decoding unit <NUM> sends satellite position error δo and satellite clock error δt to the satellite correction unit <NUM>, tropospheric delay T and ionospheric delay I to the delay calculation unit <NUM>, the signal bias CB related to the pseudorange to the second bias conversion unit <NUM>, and the signal bias PB related to the carrier phase to the first bias conversion unit <NUM>.

At step S113, the satellite calculation unit <NUM> calculates the satellite position and satellite time of the positioning satellite from a navigation message.

At step S114, the satellite correction unit <NUM> performs correction of the satellite position and correction of the satellite time. The satellite correction unit <NUM> corrects the satellite position and satellite time determined by the satellite calculation unit <NUM> using error information related to the position and time of the GNSS satellite contained in augmentation information, and sends the corrected satellite position and satellite time to the position calculation unit 29a.

At step S115, the delay calculation unit <NUM> performs calculation for atmospheric correction. The delay calculation unit <NUM> calculates a tropospheric delay amount and an ionospheric delay amount at the positioning location of the positioning apparatus <NUM> from quantities of state of the troposphere and the ionosphere contained in the augmentation information. For the ionospheric delay amount, the ionospheric delay amount is converted to a value of the frequency of signals used by the positioning apparatus <NUM> because the delay amount differs from frequency to frequency. The delay calculation unit <NUM> sends calculated tropospheric delay amount dtrop and ionospheric delay amount dion to the first correction unit <NUM> and the second correction unit <NUM>.

At step S116, the second bias conversion unit <NUM> determines whether any pseudorange signal bias CB compatible with the frequency of the ranging signal is contained in the augmentation information. If none is contained, the processing moves on to step S117. If one is contained, the processing moves on to step S118.

At step S117, the second bias conversion unit <NUM> converts the signal bias CB related to the pseudorange. As mentioned in the description of <FIG>, when the signal bias related to pseudorange contained in the augmentation information is not compatible with the ranging signal, the second bias conversion unit <NUM> acquires the conversion value Δp by making a reference 27a to the conversion table <NUM>, and converts the signal bias CBi related to pseudorange contained in the augmentation information to the pseudorange signal bias CBj compatible with the ranging signal.

At step S118, the first bias conversion unit <NUM> determines whether any carrier phase signal bias PBj compatible with the ranging signal is contained in the augmentation information. If none is contained, the processing moves on to step S119. If one is contained, the processing moves on to step S120.

At step S119, the first bias conversion unit <NUM> converts the carrier phase signal bias PBi to the carrier phase signal bias PBj. That is, the first bias conversion unit <NUM> converts the carrier phase signal bias PBi contained in augmentation information to the carrier phase signal bias PBj by using expression (<NUM>), as mentioned in the description of <FIG>.

At step S120, the second correction unit <NUM> corrects a pseudorange observable using expression (<NUM>) below. That is, the second correction unit <NUM> corrects a pseudorange observable Pj using the tropospheric delay amount dtrop and the ionospheric delay amount dion, j computed by the delay calculation unit <NUM> and the converted pseudorange signal bias CBj. FORMULA <NUM> <MAT>.

At step S121, the first correction unit <NUM> corrects a carrier phase observable using expression (<NUM>) below. The first correction unit <NUM> corrects a carrier phase observable φj using the tropospheric delay amount dtrop and the ionospheric delay amount dion, j computed by the delay calculation unit <NUM> and the converted carrier phase signal bias PBj. FORMULA <NUM> <MAT>.

At step S122, the position calculation unit 29a calculates the position, velocity, and acceleration of the positioning apparatus <NUM> using expressions (<NUM>) to (<NUM>) below. The position calculation unit 29a determines quantities of state with the Kalman filter or the least squares method based on the observation equations of expressions (<NUM>) to (<NUM>), with the quantities of state being the "position, velocity, and acceleration of the positioning apparatus <NUM>" and an integer value bias Nj, and the observable being the "pseudorange amount, carrier phase, and Doppler shift after correction".

<FIG> shows an example of applying the positioning apparatus <NUM> to PPP-RTK positioning that uses augmentation information of CLAS (Centimeter Level Augmentation Service). In the following description, GPS indicates the GPS satellite <NUM>, Galileo indicates the Galileo satellite <NUM>, and QZS indicates the quasi-zenith satellite <NUM>. The CLAS is a service that distributes error information related to satellite orbit error, satellite clock error, satellite signal bias, tropospheric delay, and ionospheric delay to positioning users. The satellite signal bias includes error information related to L1C/A, L2P, L2C, and L5 of the GPS, QZS L1C/A, L2C, and L5, and Galileo E1b and E5a. On the positioning apparatus <NUM> of the user, ranging signals for GPS L1C/A and L2C, QZS L1C/A and L2C, and Galileo E1b and E5b can be received. Thus, with a conventional positioning apparatus, correction of errors contained in a ranging signal is possible for GPS L1 C/A and L2C, QZS L1C/A and L2C, and Galileo E1b among the signals that can be received by the user's positioning terminal, while positioning by two frequencies has not been feasible with Galileo E5b. The positioning apparatus <NUM> is able to convert a satellite signal bias related to Galileo E5a of the CLAS to a signal bias for Galileo E5b through a conversion scheme of pseudorange signal bias and a conversion scheme of signal bias related to the carrier phase. Thus, the positioning apparatus <NUM> of the user can also utilize ranging signals for Galileo E5b in positioning computation.

<FIG> illustrates an effect of using the augmentation information [E5b]. As the positioning apparatus <NUM> converts the error information [E5a] of ranging signal E5a to the error information [E5b] usable with the ranging signal E5b, the error information can be used for each of the six kinds of ranging signals. Consequently, as shown in <FIG>, positioning errors decrease when error information is used for each of the six kinds of ranging signals by making use of converted error information. The length of a side of a broken-line cell represents an error of <NUM>. The left side on the horizontal axis indicates west and the right side indicates east, and the upper side on the vertical axis indicates north and the lower side indicates south.

As the number of ranging signals available for positioning computation increases, the accuracy of a float solution improves. Further, since an integer value bias can be turned into an integer, further improvement in positioning accuracy and shortening of initial convergence time become possible.

<FIG> shows an example of pieces of error information that can be converted mutually. In <FIG>, Galileo, BeiDou, GLONASS, and GPS are illustrated as GNSS. Galileo [E5a] and Galileo [E5b] can be converted. Galileo [E5b] and Galileo [E5altboc] can be converted. Further, BeiDou [B1I] and BeiDou [B1C] can be converted.

As described above, the positioning apparatus <NUM> is a positioning apparatus to process a first ranging signal having a first frequency and a second ranging signal having a second frequency which are transmitted from a plurality of positioning satellites.

As described above, the first augmentation information, like the signal bias CBi related to pseudorange and the signal bias PBi related to carrier phase, is transmitted from one positioning satellite of a plurality of positioning satellites. In the description above, the one positioning satellite is the quasi-zenith satellite <NUM>. The first augmentation information is provided in a state space representation from the quasi-zenith satellite <NUM>.

Note that the first augmentation information, like the signal bias CBi related to pseudorange and the signal bias PBi related to carrier phase, may also be transmitted from a public line such as the Internet. The first augmentation information is provided in a state space representation.

The first augmentation information is obtained from outside. As an example of the outside, the first augmentation information is obtained from a transmission device that transmits positioning augmentation information including the first augmentation information. The transmission device can be a device like the quasi-zenith satellite <NUM> or an augmentation information generation apparatus <NUM>, discussed later in Embodiment <NUM>.

The first augmentation information is dependent on the first frequency, and the conversion unit converts the first augmentation information to the second augmentation information so as to match the second frequency. In Embodiment <NUM>, the signal bias CBi and the signal bias PBi as the first augmentation information are dependent on the "frequency of the ranging signal E5a of the Galileo satellite <NUM>", or the first frequency. The conversion unit converts the first augmentation information to the second augmentation information so that the first augmentation information matches the "frequency of the ranging signal E5b of the Galileo satellite <NUM>", or the second frequency. The second augmentation signal is the signal bias CBj and the signal bias PBj.

Referring to <FIG> and <FIG>, a positioning apparatus <NUM> in Embodiment <NUM> is described. The positioning apparatus <NUM> is a device that performs positioning by the PPP-AR positioning approach.

<FIG> is a hardware configuration diagram of the positioning apparatus <NUM>.

<FIG> is a flowchart illustrating the operation of the positioning apparatus <NUM>.

Since in the PPP-AR no augmentation information related to atmospheric delay amount is included, the position calculation unit 29a performs model correction of the atmospheric delay amount or estimates the atmospheric delay amount along with user position. Thus, the delay calculation unit <NUM> is not present in the positioning apparatus <NUM>. Additionally, in the positioning apparatus <NUM>, processing at the second correction unit <NUM>, the first correction unit <NUM>, and the position calculation unit 29a is different.

Steps S211 to S222 correspond to steps S111 to S122. In Embodiment <NUM>, there is no step corresponding to step S115, since for the tropospheric delay and the ionospheric delay, model correction is performed or they are estimated by an estimation filter along with user position.

Specifically, step S111 corresponds to step S211; step S112 corresponds to step S212; step S113 corresponds to step S213; and step S114 corresponds to step S214. Further, step S116 corresponds to step S216; step S117 corresponds to step S217; step S118 corresponds to step S218; step S119 corresponds to step S219; step S120 corresponds to step S220; step S121 corresponds to step S221; and step S122 corresponds to step S222.

As the processing at steps S211 to S214 and steps S216 to S219 is the same as in Embodiment <NUM>, steps S220 to S222 will be described.

At step S220, the second correction unit <NUM> corrects a pseudorange observable using expression (<NUM>) below. Specifically, the second correction unit <NUM> corrects an observable Pj of pseudorange using the converted pseudorange signal bias CBj. FORMULA <NUM> <MAT>.

At step S221, the first correction unit <NUM> corrects the observable of the carrier phase using expression (<NUM>) below. Specifically, the first correction unit <NUM> corrects an observable φj of the carrier phase using the converted carrier phase signal bias PBj. FORMULA <NUM> <MAT>.

At step S222, the position calculation unit 29a uses expressions (<NUM>) to (<NUM>) below to estimate the position, velocity, and acceleration of the positioning apparatus <NUM> with the Kalman filter or the least squares method. For the tropospheric delay and the ionospheric delay, the position calculation unit 29a performs model correction of the atmospheric delay or estimates the atmospheric delay with an estimation filter along with the user position. The position calculation unit 29a also determines the uncertainty of the carrier phase.

According to Embodiment <NUM>, the signal bias CBi related to pseudorange can be converted to the signal bias CBj related to pseudorange and the signal bias PBi related to the carrier phase can be converted to the signal bias PBj related to the carrier phase also for a positioning apparatus that performs positioning by the PPP-AR positioning approach. Thus, the accuracy of positioning by the PPP-AR can be improved.

Embodiment <NUM> describes an augmentation information generation apparatus <NUM> that generates augmentation information by using the conversion of expression (<NUM>), described in <FIG>, and the conversion of expression (<NUM>).

<FIG> is a hardware configuration diagram of the augmentation information generation apparatus <NUM>.

<FIG> is a flowchart illustrating the operation of the augmentation information generation apparatus <NUM>.

A conversion unit of the augmentation information generation apparatus <NUM> converts, based on the first frequency and the second frequency, augmentation information transmitted from a first positioning satellite for correcting the first calculation information for position calculation, the first calculation information being contained in a first ranging signal having the first frequency, to the second augmentation information for correcting the second calculation information for position calculation, the second calculation information being contained in a second ranging signal having the second frequency transmitted from a positioning satellite.

A first bias conversion unit <NUM> and a second bias conversion unit <NUM> form the conversion unit as described later.

The augmentation information generation apparatus <NUM> includes a GNSS data reception unit <NUM>, a processor <NUM>, a main storage device <NUM>, an auxiliary storage device <NUM>, and a transmission device <NUM> as hardware.

The GNSS data reception unit <NUM> receives ranging information and navigation messages from multiple GNSS receivers. The GNSS receivers are fixed in an environment with open surroundings. For example, the GNSS receivers are set at GPS-based control station. The GNSS receivers receive ranging signals and navigation messages for generating augmentation information from positioning satellites and deliver these signals to the augmentation information generation apparatus <NUM>.

The processor <NUM> includes an augmentation information generation unit <NUM>, a first bias conversion unit <NUM>, a second bias conversion unit <NUM>, and an augmentation information compression unit <NUM> as functional components. These functional components are implemented by a program. The program is stored in the auxiliary storage device <NUM>. The function of the first bias conversion unit <NUM> is the same as the function of the first bias conversion unit <NUM> in Embodiment <NUM>. The function of the second bias conversion unit <NUM> is the same as the function of the second bias conversion unit <NUM> in Embodiment <NUM>. The first bias conversion unit <NUM> and the second bias conversion unit <NUM> are the conversion unit. The augmentation information compression unit <NUM> is a transmission control unit. The transmission control unit provides the first augmentation information in a state space representation by relaying via the quasi-zenith satellite <NUM>.

The auxiliary storage device <NUM> stores the conversion table <NUM>. Referring to <FIG>, the operation of the augmentation information generation apparatus <NUM> is described below.

At step S301, the GNSS data reception unit <NUM> receives ranging signals and navigation messages as GNSS data from multiple GNSS data receivers: a GNSS data receiver #<NUM> to a GNSS data receiver #N. The ranging signals include information such as carrier phase, pseudorange, and Doppler.

At step S302, the augmentation information generation unit <NUM> calculates augmentation information from the navigation messages and ranging signals received by the GNSS data reception unit <NUM>. This augmentation information is satellite orbit error, satellite clock error, satellite phase bias, ionospheric delay amount, and tropospheric delay amount.

At step S303, the second bias conversion unit <NUM> determines whether any pseudorange signal bias CBj compatible with the ranging signals that are acquired by the positioning user is contained in the augmentation information generated by the augmentation information generation unit <NUM>. If the second bias conversion unit <NUM> determines none is contained (NO at step S303), the processing moves on to step S304, and if it determines one is contained (YES at step S303), the processing moves on to step S305.

At step S304, the second bias conversion unit <NUM> makes a reference 227a to the conversion table <NUM> and converts the pseudorange signal bias CBi generated by the augmentation information generation unit <NUM> to the pseudorange signal bias CBj.

At step S305, the first bias conversion unit <NUM> determines whether any carrier phase signal bias PBj compatible with the ranging signals that are acquired by the positioning user is contained in the augmentation information generated by the augmentation information generation unit <NUM>. If the first bias conversion unit <NUM> determines none is contained (NO at step S305), the processing moves on to step S306, and if it determines one is contained (YES at step S305), the processing moves on to step S307.

At step S306, the first bias conversion unit <NUM> converts the carrier phase signal bias PBi to the carrier phase signal bias PBj with PBj= F(λi, λj, CBi, PBi) using the pseudorange signal bias CBi generated by the augmentation information generation unit <NUM>, the values of carrier phase signal bias PBi, λ<NUM>, and λj, and expression (<NUM>).

At step S307, the augmentation information compression unit <NUM> compresses the generated augmentation information so as to meet the limitation of line capacity in distribution to the user.

At step S308, the transmission device <NUM> distributes the compressed augmentation information to the user via a satellite or a land line.

According to Embodiment <NUM>, the augmentation information generation apparatus <NUM> converts the signal bias CBi related to pseudorange to the signal bias CBj related to pseudorange, converts the signal bias PBi related to carrier phase to the signal bias PBj related to carrier phase, and transmits them in augmentation information.

Thus, the user need not have a positioning apparatus with conversion functionality, such as the positioning apparatus <NUM> or the positioning apparatus <NUM>, which improves the user's convenience.

Embodiment <NUM> is an embodiment in which the signal bias CBi related to pseudorange is converted to the signal bias CBj related to pseudorange and the signal bias PBi related to carrier phase is converted to the signal bias related to the carrier phase PBj by further using an error value ΔI of the ionospheric delay amount in addition to the configuration of Embodiment <NUM> described above.

Accordingly, only differences from Embodiment <NUM> will be described in the following description and the other arrangements will not be described.

<FIG> is a block diagram showing a positioning apparatus <NUM> according to Embodiment <NUM>.

In <FIG>, the positioning apparatus <NUM> has an ionospheric error calculation unit <NUM> to calculate the error ΔI of the ionospheric delay amount in addition to the configuration of the positioning apparatus <NUM> described in Embodiment <NUM>.

The ionospheric error calculation unit <NUM> calculates the error value ΔI of the ionospheric delay amount, which is the difference between a predicted value of the ionospheric delay amount at the user's positioning location and the value of the ionospheric delay amount calculated by the delay calculation unit <NUM> from ionospheric delay information contained in augmentation information.

Specifically, the ionospheric error calculation unit <NUM> uses a Klobuchar model to calculate an ionospheric delay amount error value from ionospheric delay parameters contained in a navigation message acquired at the GNSS reception unit <NUM>.

Alternatively, the ionospheric error calculation unit <NUM> may calculate the error value ΔI of the ionospheric delay amount from a geometry-free combination of pseudorange observables, which are the user's ranging signals, calculated at the delay calculation unit <NUM>.

In <FIG>, the first bias conversion unit <NUM> and the second bias conversion unit <NUM> each acquire the error value ΔI of the ionospheric delay amount from the ionospheric error calculation unit <NUM> and convert the signal bias related to carrier phase and the signal bias related to pseudorange, respectively. Their respective conversion processes will be described later.

<FIG> is a flowchart illustrating the operation of the positioning apparatus <NUM> according to Embodiment <NUM>.

In <FIG>, steps S411 to S416, step S417, step S418, and steps S419 to S422 correspond to steps S111 to S122 in <FIG> of Embodiment <NUM>.

In <FIG>, step S416-<NUM> is present between step S416 corresponding to step S116 and step S417 corresponding to step S117, compared to <FIG>.

In addition, step S418-<NUM> is present between step S418 corresponding to step S118 and step S419 corresponding to step S119.

Thus, regarding <FIG>, only steps with different processing from <FIG> will be described.

As steps S411 to S416 are similar processing to steps S111 to S116, they will not be described.

At step S416-<NUM>, the ionospheric error calculation unit <NUM> calculates the error ΔI of the ionospheric delay amount and outputs the error ΔI of the ionospheric delay amount to the second bias conversion unit <NUM>.

At step S417, the second bias conversion unit <NUM> performs conversion of the signal bias related to the pseudorange further using the error ΔI of the ionospheric delay amount, compared to step S117 in Embodiment <NUM>.

At step S418-<NUM>, the ionospheric error calculation unit <NUM> calculates the error ΔI of the ionospheric delay amount and outputs the error ΔI of the ionospheric delay amount to the first bias conversion unit <NUM>. If the error ΔI of the ionospheric delay amount was calculated at step S416-<NUM>, the ionospheric error calculation unit <NUM> may use the calculated error ΔI.

At step S419, the first bias conversion unit <NUM> performs conversion of the signal bias related to the carrier phase further using the error ΔI of the ionospheric delay amount, compared to step S119 in Embodiment <NUM>.

As the contents of processing at steps S420 to S422 are the same as steps S120 to S122, they will not be described.

A conversion process using the error value ΔI of the ionospheric delay amount at the first bias conversion unit <NUM> and the second bias conversion unit <NUM> is described below.

The second bias conversion unit <NUM> converts the signal bias CBi related to pseudorange to the signal bias CBj related to pseudorange using expression (<NUM>) shown below.

Expression (<NUM>) additionally includes a term for the error value ΔI of the ionospheric delay amount, compared to expression (<NUM>). FORMULA <NUM>.

The first bias conversion unit <NUM> converts the signal bias PBi for the carrier phase to the signal bias PBj for the carrier phase using expression (<NUM>) shown below.

Expression (<NUM>) additionally includes a term for the error value ΔI of the ionospheric delay amount, compared to expression (<NUM>). FORMULA <NUM>.

The way of computing expressions (<NUM>) and (<NUM>) is shown below.

The observation equation for the case of assuming that an error of ΔI is included in the ionospheric delay amount contained in augmentation information is the following, where Ii is the true value of the ionospheric delay.

Let I'i be an ionospheric delay amount having an error of ΔI and let δP'/δφ' be the pseudorange/carrier phase signal bias at that time.

The following relationships can be derived: <MAT>.

Conversion formula of the pseudorange signal bias: <MAT>.

Conversion formula of the carrier phase signal bias: <MAT>.

Embodiment <NUM> can improve the accuracy of signal bias conversion to enhance the positioning accuracy since it converts the pseudorange signal bias and the carrier phase signal bias by using the error value ΔI of the ionospheric delay amount based on the foregoing configuration and operation.

As Embodiment <NUM>, the hardware configurations of the positioning apparatus <NUM> of <FIG>, the positioning apparatus <NUM> of <FIG>, the positioning apparatus <NUM> of <FIG>, and the augmentation information generation apparatus <NUM> of <FIG> are supplementarily described.

The hardware configuration of the positioning apparatus is described first. In the positioning apparatuses of <FIG>, <FIG>, and <FIG>, the functions of the satellite calculation unit <NUM>, the first decoding unit <NUM>, the second decoding unit <NUM>, the satellite correction unit <NUM>, the delay calculation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, the first correction unit <NUM>, the second correction unit <NUM>, and the position calculation unit 29a are implemented by a program. However, the functions of the satellite calculation unit <NUM>, the first decoding unit <NUM>, the second decoding unit <NUM>, the satellite correction unit <NUM>, the delay calculation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, the first correction unit <NUM>, the second correction unit <NUM>, and the position calculation unit 29a may be implemented by hardware.

<FIG> shows a configuration in which the functions of the positioning apparatus are implemented by hardware. An electronic circuit <NUM> of <FIG> is a dedicated electronic circuit to implement the functions of the satellite calculation unit <NUM>, the first decoding unit <NUM>, the second decoding unit <NUM>, the satellite correction unit <NUM>, the delay calculation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, the first correction unit <NUM>, the second correction unit <NUM>, and the position calculation unit 29a of the positioning apparatus. The electronic circuit <NUM> is connected with a signal line <NUM>. The electronic circuit <NUM> is specifically a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA, an ASIC, or a FPGA. GA is an abbreviation of Gate Array. ASIC is an abbreviation of Application Specific Integrated Circuit. FPGA is an abbreviation of Field-Programmable Gate Array.

The functions of the components of the positioning apparatus may be implemented in one electronic circuit or distributed across a plurality of electronic circuits. Some functions of the functional components of the positioning apparatus may be implemented by an electronic circuit and the remaining functions may be implemented by software.

The respective functions of the satellite calculation unit <NUM>, the first decoding unit <NUM>, the second decoding unit <NUM>, the satellite correction unit <NUM>, the delay calculation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, the first correction unit <NUM>, the second correction unit <NUM>, and the position calculation unit 29a of the positioning apparatus may be implemented by circuitry. For the positioning apparatus, a "unit" may be read as "circuit" or "step" or "procedure" or "process" or "circuitry".

In the augmentation information generation apparatus <NUM> of <FIG>, the functions of the augmentation information generation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, and the augmentation information compression unit <NUM> are implemented by a program. However, the functions of the augmentation information generation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, and the augmentation information compression unit <NUM> of the augmentation information generation apparatus <NUM> may be implemented by hardware, as with the positioning apparatus. That is, the augmentation information generation apparatus <NUM> may also be implemented by the electronic circuit <NUM> shown in <FIG>, as with the positioning apparatus. Likewise, the functions of the augmentation information generation unit <NUM>, the first bias conversion unit <NUM>, the second bias conversion unit <NUM>, and the augmentation information compression unit <NUM> of the augmentation information generation apparatus <NUM> may be implemented by circuitry. For the augmentation information generation apparatus <NUM>, a "unit" may be read as "circuit" or "step" or "procedure" or "process" or "circuitry".

An operation procedure of the positioning apparatus corresponds to a positioning method. A program to implement the operation of the positioning apparatus corresponds to a positioning program. The positioning program may be provided stored on a computer-readable recording medium or provided as a program product.

An operation procedure of the augmentation information generation apparatus <NUM> corresponds to an augmentation information generation method. A program to implement the operation of the augmentation information generation apparatus <NUM> corresponds to an augmentation information generation program. The augmentation information generation program may be provided stored on a computer-readable recording medium or provided as a program product.

Claim 1:
A positioning apparatus (<NUM>) configured to process a first ranging signal (E5a) having a first frequency and a second ranging signal (E5b) having a second frequency which are transmitted from a plurality of positioning satellites (<NUM>, <NUM>, <NUM>), the positioning apparatus (<NUM>) comprising:
a conversion unit (<NUM>,<NUM>) configured to convert first augmentation information for correcting first calculation information for position calculation contained in the first ranging signal (E5a) to second augmentation information for correcting second calculation information for position calculation contained in the second ranging signal (E5b); and
a correction unit (<NUM>,<NUM>) configured to correct the second calculation information using the second augmentation information; wherein
the first calculation information is a carrier phase contained in the first ranging signal (E5a),
the second calculation information is a carrier phase contained in the second ranging signal (E5b),
the first augmentation information is a signal bias (PBi) for correcting the carrier phase contained in the first ranging signal (E5a),
the second augmentation information is a signal bias (PBj) for correcting the carrier phase contained in the second ranging signal (E5b), and
the conversion unit (<NUM>,<NUM>) is configured to convert the first augmentation information to the second augmentation information based on an expression of linear combination of
the signal bias (PBi) as the first augmentation information (PBi) for the carrier phase contained in the first ranging signal (E5a) and
a signal bias (CBi) related to a pseudorange, the signal bias (CBi) related to the pseudorange being information for correcting the pseudorange contained in the first ranging signal (E5a).