JP2012242107A - Multipath detection method, multipath detection program, multipath detection device, and gnss signal receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a multipath detection method capable of more accurately calculating multipath delay quantity.SOLUTION: A receiving signal is acquired (S101) and a multipath state including an amplitude ratio between a direct wave signal and an indirect wave signal is detected (S102). By using three pairs of early correlation processing signals and late correlation processing signals, a first pseudo distance ρ, a second pseudo distance ρand a third pseudo distance ρare respectively calculated (S103). By using the first pseudo distance ρ, the second pseudo distance ρand the third pseudo distance ρ, a first pseudo distance difference value Δρand a second pseudo distance difference value Δρare calculated (S104). The first pseudo distance difference value Δρand the second pseudo distance difference value Δρare corrected and normalized based on the amplitude ratio (S105). The multipath delay quantity is determined from a relation table between the pseudo distance difference values and the multipath delay quantity based on the normalized first pseudo distance difference value Δρand second pseudo distance difference value Δρ(S106).

Description

  The present invention relates to a multipath error detection method for detecting a multipath error of a GNSS signal that may occur depending on a reception environment.

  In a GNSS receiver that receives a GNSS (Global Navigation Satellite System) signal such as a GPS (Global Positioning System) signal and measures a pseudorange, multipath is one of the factors that degrade the measurement accuracy of the pseudorange. is there. Multipath occurs when a multipath signal, which is a GNSS signal that reaches the receiver after being reflected by a high-rise building or the like around the receiver, is received together with the GNSS signal that has arrived directly.

  Conventionally, as shown in Patent Document 1 and Patent Document 2, various methods and apparatuses for detecting a multipath have been devised. For example, in the apparatus of Patent Literature 1, the current pseudo distance is estimated based on the previously calculated pseudo distance, and if the difference between the current estimated pseudo distance and the present calculated pseudo distance is equal to or greater than a predetermined threshold, the multipath is determined. Judging that there is. Further, in the apparatus of Patent Document 2, if the difference value between the actual correlation result by the received signal and the replica signal and the ideal correlation result on the assumption that there is no multipath is greater than or equal to a predetermined threshold value, Judge that there is multipath. Further, the difference value is estimated and calculated from a predetermined delay amount table in accordance with the difference value.

JP 2002-328157 A JP-A-2005-207815

  However, the conventional multipath detection methods described in the above-mentioned patent documents can simply detect the presence or absence of multipath, detect the presence or absence of multipath based on an ideal correlation result, and delay amount Therefore, an accurate multipath delay amount cannot be calculated.

  An object of the present invention is to realize a multipath detection method capable of calculating a multipath delay amount more accurately than simply detecting the presence or absence of multipath.

  The present invention relates to a multipath detection method, a multipath detection program, and a multipath detection apparatus that detect a multipath generated when a GNSS signal is received. This multipath detection method includes an early rate correlation signal generation step, a pseudorange calculation step, a pseudorange difference value calculation step, and a multipath delay amount calculation step.

  In the early-late correlation processing signal generation step, at least three pairs of early correlation processing signals and late correlation processing signals are generated based on the correlation processing signals having the spreading code of the GNSS signal. Generate. At this time, the code phase interval is made different between the sets of correlation processing signals or the correlation processing codes are made different.

  In the pseudo distance calculation step, correlation processing is performed on each set of Early correlation processing signal and Late correlation processing signal and the received signal, and a pseudo distance is calculated from each correlation processing result.

  In the pseudo distance difference value calculating step, the pseudo distance difference value is calculated using a combination of different pseudo distances.

  In the multipath delay amount calculation step, the multipath delay amount is calculated based on at least two pseudo-range difference values.

  In this method, the pseudo distance based on the EL correlation value that is the difference between the early correlation value and the late correlation value differs depending on the code interval between the early correlation processing signal and the late correlation processing signal and each correlation processing code. Moreover, the fact that it differs depending on the amount of multipath delay is utilized. Furthermore, this method utilizes the fact that the pseudo-range difference value obtained by subtracting each pseudo-distance differs depending on the combination of the pseudo-distance calculation specification and the pseudo-distance, and also differs depending on the multipath delay amount. If a plurality of pseudo distance difference values having such characteristics are calculated, the calculation specifications of each pseudo distance difference value (specifically, the specifications of the Early correlation processing signal and the Late correlation processing signal), and the pseudo distance difference value The multipath delay amount is substantially uniquely determined by the combination with the above set.

  In the multipath detection method of the present invention, the pseudo distance difference value calculating step sets one reference pseudo distance and calculates each pseudo distance difference value based on the difference with respect to the reference pseudo distance.

  This method shows a specific calculation method of the pseudorange difference value.

  In the multipath detection method according to the present invention, the early-late correlation processing signal generation step includes at least three pairs of early correlation processing signals and late correlation processing signals as a single set. The correlation processing signals are used to generate the code phase intervals differently.

  This method shows a specific method for generating each pair of the Early correlation processing signal and the Late correlation processing signal. By using this method, three EL correlation values having different spacings can be calculated for one type of correlation processing signal. If these three EL correlation values are used, two difference values for the pseudorange can be calculated, and the multipath delay amount can be calculated. Therefore, for example, the multipath delay amount can be calculated using only the replica signal of the GNSS signal used for code acquisition and code tracking.

  In addition, the multipath detection method of the present invention includes a subcarrier generation step for generating subcarriers to be superimposed on the correlation processing signal. The signal processing step for early late correlation processing includes at least three pairs of early correlation processing signals and late correlation processing signals, a basic correlation processing signal generated from a spreading code, and a spread in which subcarriers are superimposed. It is generated using the subcarrier superposition type correlation processing signal generated from the code.

  This method shows a specific method for generating each pair of the Early correlation processing signal and the Late correlation processing signal. By using this method, there are a plurality of types of correlation processing signals before code phase control for generating each set of Early correlation processing signals and Late correlation processing signals. For example, the multipath delay amount is calculated using the replica signal of the GNSS signal described above and a signal obtained by superimposing a predetermined subcarrier on the replica signal. Thereby, the characteristic of the pseudo-range difference value with respect to the multipath delay amount can be made more diverse.

  In the multipath detection method of the present invention, the multipath delay amount calculation step stores in advance a relationship table between at least two combinations of pseudorange difference values and the multipath delay amount. In the multipath delay amount calculation step, the multipath delay amount is calculated using each calculated pseudo distance difference value and the relation table.

  In this method, for each set of pseudorange difference values, each pseudorange difference value with respect to the multipath delay amount is stored as a relation table, and the relation table is read with reference to each calculated pseudorange difference value. Determine the amount of delay. Thereby, it is not necessary to perform the calculation processing of the multipath delay amount every time each pseudo distance difference value is acquired, and the multipath delay amount can be calculated at a higher speed.

  In addition, the multipath detection method of the present invention includes a multipath state detection step of detecting an amplitude ratio between the direct wave signal and the indirect wave signal of the GNSS signal that causes multipath. In the multipath delay amount calculating step, the multipath delay amount is calculated in consideration of the amplitude ratio.

  In this method, correction based on the amplitude ratio is performed on the calculated multipath delay amount. As a result, a more accurate multipath delay amount can be calculated.

  The present invention also relates to a GNSS signal receiving method, a GNSS signal receiving program, and a GNSS signal receiving apparatus. The GNSS signal receiving method of the present invention includes any of the multipath detection methods described above, and has a positioning calculation step of performing a positioning calculation using the pseudorange and the multipath delay amount.

  In this method, since the positioning calculation is performed using the multipath delay amount accurately calculated as described above, a highly accurate positioning result can be obtained.

  According to the present invention, the amount of multipath delay can be detected more accurately than in the past.

It is a block diagram which shows the main structures of the GNSS signal receiver 1 containing the multipath detection apparatus which concerns on 1st Embodiment. It is a figure which shows the characteristic of the pseudorange difference value with respect to the amount of multipath delays when the multipath detection method according to the first embodiment is used. 5 is a flowchart of a multipath detection method according to the first embodiment. It is a block diagram which shows the main structures of GNSS signal receiver 1A containing the multipath detection apparatus which concerns on 2nd Embodiment. It is a waveform diagram of a signal for BPSK correlation processing, a BOCcos subcarrier, a signal for BOCcos correlation processing, a BOCmod subcarrier, and a signal for BOCmod correlation processing. It is a figure which shows the characteristic of the pseudorange difference value with respect to the amount of multipath delays when the multipath detection method according to the second embodiment is used. It is a block diagram which shows the main structures of the GNSS signal receiver 1B containing the multipath detection apparatus which concerns on 3rd Embodiment. It is a figure which shows the characteristic of the pseudorange difference value with respect to the amount of multipath delays when the multipath detection method according to the third embodiment is used. It is a block diagram which shows the main structures of GNSS signal receiver 1C containing the multipath detection apparatus which concerns on 4th Embodiment. It is a figure which shows the characteristic of the pseudorange difference value with respect to the amount of multipath delays when the multipath detection method according to the fourth embodiment is used. It is a block diagram which shows the main structures of the mobile terminal 300 provided with the GNSS signal receiver 1 of embodiment of this invention.

  A multipath detection method, a multipath detection program, and a multipath detection apparatus according to an embodiment of the present invention will be described. In the present embodiment, a GNSS signal reception method, a GNSS signal reception program, and a multipath detection method, a multipath detection program, and a multipath detection device in a GNSS signal reception device are shown as examples. In the present embodiment, a GPS signal is used as the GNSS signal.

  FIG. 1 is a block diagram illustrating a main configuration of a GNSS signal receiving apparatus 1 including a multipath detection apparatus according to the present embodiment.

  The GNSS signal receiving apparatus 1 includes an antenna 50, an RF processing unit 51, a multipath state detection unit 52, a carrier NCO 53, a baseband conversion unit 54, and a positioning calculation unit 55, as well as code tracking and multipath delay calculation. The functional part which performs is provided.

  The antenna 50 receives the GPS signal broadcast from each GPS satellite and outputs the received signal to the RF processing unit 51. At this time, the antenna 50 is an array antenna in which a plurality of individual antennas are arranged in a predetermined pattern.

  The RF processing unit 51 down-converts the received GPS signal to generate an intermediate frequency signal (IF signal) and outputs it to the multipath state detection unit 52 and the baseband conversion unit 54. The RF processing unit 51 is preferably provided for each individual antenna.

  The multipath state detection unit 52 applies the MUSIC method to the IF signals obtained by receiving a plurality of individual antennas, so that the arrival direction of the direct wave signal and the indirect wave signal constituting the reception signal, the indirect wave The number of signals and the amplitude ratio between the direct wave signal and the indirect wave signal are calculated. The multipath state detection unit 52 outputs multipath state information having at least an amplitude ratio between the direct wave signal and the indirect wave signal (hereinafter simply referred to as an amplitude ratio) to the multipath delay amount calculation unit 15. If another multipath state detection method is used and the multipath state can be detected even with a single antenna, the antenna 50 may be a single antenna, and in this case, only one RF processing unit 51 may be used.

The baseband converting unit 54, by multiplying the carrier frequency signal from the carrier NCO53 the IF signal to generate a baseband signal S _B. The baseband signal S _B is output to the function unit for performing the code tracking and multipath delay amount calculation. The functional unit that performs this code tracking and multipath delay amount calculation corresponds to the “multipath detection device” of the present invention.

Function unit for performing a code tracking and multipath delay time calculation is described below a detailed structure and process, using the so-called Early-Late correlation processing result, as well as tracking processing a baseband signal S _B of the GPS signals, Calculate the multipath delay amount. Then, this functional unit outputs the Prompt correlation value, the pseudo distance obtained from the Early-Late correlation processing result, and the multipath delay amount to the positioning calculation unit 55.

  The positioning calculation unit 55 decodes the navigation message from the Prompt correlation value. The positioning calculation unit 55 performs positioning calculation by a known method using the navigation message and the pseudo distance. At this time, the positioning calculation unit 55 can perform more accurate positioning calculation by using the carrier phase from the carrier NCO 53. Furthermore, the positioning calculation unit 55 can perform the positioning calculation with higher accuracy by correcting the pseudo distance and the like using the multipath delay amount calculated with high accuracy.

  Next, a specific configuration and processing of a functional unit that performs code tracking and multipath delay amount calculation will be described. As shown in FIG. 1, functional units that perform code tracking and multipath delay amount calculation are a P correlation unit 11, an E-L correlation unit 121, 122, 123, a pseudo distance calculation unit 131, 132, 133, and an adder. 141, 142, a multipath delay amount calculation unit 15, and a correlation processing signal generation unit 20.

The baseband signal _{S B} is, P correlation unit 11, the first E-L correlation unit 121, the second E-L correlation unit 122, is input to a third E-L correlator 123.

First, the configuration of the correlation processing signal generator 20 for generating a correlation processing signals utilizing the correlation between the baseband signal S _B. Based on the first code phase difference information output from the E-L correlation unit 121, the correlation processing signal generation unit 20 includes a spreading code (C / A code or P code) used for the GPS signal. Next, each correlation processing signal including the correlation processing signal is generated.

Correlation signal generating unit 20 at the timing as E-L correlation value becomes 0, and generates a Prompt correlation processing signals SR _P. Correlation signal generating unit 20, around the timing the timing of the Prompt correlation processing signals SR _P, code phase interval (spacing) of a first 1Late correlation process and the 1Early correlation processing signals _{SR E1} consisting 0.1chip A signal SR _L1 is generated. Prompt correlation signal SR _P is outputted to the P correlator 11. The first Early correlation processing signal SR _E1 and the first Late correlation processing signal SR _L1 are output to the EL correlation unit 121.

Correlation-phase signal generating portion 20, around the timing the timing of the Prompt correlation processing signals SR _P, code phase interval (spacing) of a first 2Late correlation process and the 2Early correlation processing signals _{SR E2} consisting 1.0chip A signal SR _L2 is generated. Second Early correlation processing signal SR _E2 and second Late correlation processing signal SR _L2 are output to EL correlation section 122.

Correlation signal generating unit 20, around the timing the timing of the Prompt correlation processing signals SR _P, code phase interval (spacing) of a first 3Early correlation processing signals _{SR E3} and the 3Late correlation processing consisting 1.2chip A signal SR _L3 is generated. The third early correlation processing signal SR _E3 and the third late correlation processing signal SR _L3 are output to the E-L correlation unit 123.

P correlation unit 11 outputs the Prompt correlation value by multiplying the signal Prompt correlation processing SR _P and the baseband signal _{S B.} The Prompt correlation value is output to the positioning calculation unit 56.

E-L correlation unit 121 calculates a first 1Early correlation value by multiplying the first 1Early correlation processing signals _{SR E1} and the baseband signal _{S B.} E-L correlation unit 121 calculates a first 1Late correlation value by multiplying the first 1Late correlation processing signals _{SR L1} and the baseband signal _{S B.} The E-L correlation unit 121 subtracts the first Late correlation value from the first Early correlation value to calculate a first EL correlation value. The E-L correlation unit 121 integrates the first E-L correlation values for a predetermined time, calculates first code phase difference information, and outputs the first code phase difference information to the pseudo distance calculation unit 131. The first code phase difference information is also output to the correlation processing signal generation unit 20.

E-L correlation unit 122 calculates a first 2Early correlation value by multiplying the first 2Early correlation processing signals _{SR E2} and the baseband signal _{S B.} E-L correlation unit 122 calculates a first 2Late correlation value by multiplying the first 2Late correlation processing signals _{SR L2} and the baseband signal _{S B.} The E-L correlation unit 122 subtracts the second Late correlation value from the second Early correlation value to calculate a second EL correlation value. The E-L correlation unit 122 accumulates the second E-L correlation values for a predetermined time, calculates second code phase difference information, and outputs the second code phase difference information to the pseudo distance calculation unit 132.

E-L correlation unit 123 calculates a first 3Early correlation value by multiplying the first 3Early correlation processing signals _{SR E3} and the baseband signal _{S B.} E-L correlation unit 123 calculates a first 3Late correlation value by multiplying the first 3Late correlation processing signals _{SR L3} and the baseband signal _{S B.} The E-L correlation unit 123 subtracts the third Late correlation value from the third Early correlation value to calculate a third E-L correlation value. The E-L correlation unit 123 integrates the third E-L correlation values for a predetermined time, calculates third code phase difference information, and outputs the third code phase difference information to the pseudo distance calculation unit 133.

Pseudorange calculation unit 131 first calculates a pseudo-range [rho ₁ using the first code phase difference information based on the 1E-L correlation values. The pseudo distance calculation unit 131 outputs the first pseudo distance ρ ₁ to the adders 141 and 142.

Pseudorange calculator 132, second calculates the pseudorange [rho ₂ using a second code phase difference information based on the 2E-L correlation values. The pseudo distance calculation unit 132 outputs the second pseudo distance ρ ₂ to the adder 141.

The pseudo distance calculation unit 133 calculates the third pseudo distance ρ ₃ using the third code phase difference information based on the third E-L correlation value. The pseudo distance calculation unit 133 outputs the third pseudo distance ρ ₃ to the adder 142.

The adder 141 calculates the first pseudo distance difference value Δρ ₂₁ by subtracting the first pseudo distance ρ ₁ from the second pseudo distance ρ ₂ and outputs the first pseudo distance difference value Δρ ₂₁ to the multipath delay amount calculation unit 15.

The adder 142 calculates the second pseudo distance difference value Δρ ₃₁ by subtracting the first pseudo distance ρ ₁ from the third pseudo distance ρ ₃ and outputs the second pseudo distance difference value Δρ ₃₁ to the multipath delay amount calculation unit 15.

  The method of combining the pseudo distances for calculating the pseudo distance difference value is not limited to this, and other combinations may be used. However, as shown in the present embodiment, each pseudo-range difference value may be calculated based on one pseudo-distance, and furthermore, based on the pseudo-distance based on the code phase difference information used for generating the correlation processing signal. Better to use.

The multipath delay amount calculation unit 15 calculates the multipath delay amount based on the first pseudo distance difference value Δρ ₂₁ and the second pseudo distance difference value Δρ ₃₁ . At this time, the multipath delay amount calculation unit 15 calculates the multipath delay amount with reference to the multipath state information.

  Specifically, the multipath delay amount calculation unit 15 calculates the multipath delay amount by the following process. FIG. 2 is a diagram showing the characteristics of the pseudorange difference value with respect to the multipath delay amount when the multipath detection method according to the present embodiment is used.

2, a solid line indicates a transition of the first pseudorange difference value [Delta] [rho] ₂₁ to multipath delay, a broken line indicates a transition of the second pseudorange difference value [Delta] [rho] ₃₁ to multipath delay. As shown in FIG. 2, a first pseudorange difference value [Delta] [rho] ₂₁ In the second pseudorange difference value [Delta] [rho] _31, the transition state to multipath delay is different.

For example, as shown in FIG. 2, when the first pseudo-range difference value Δρ ₂₁ is about 23 m, the multipath delay amount is about 60 m or about 330 m. When the second pseudo distance difference value Δρ ₃₁ is about 30 m, the multipath delay amount is about 75 m or about 330 m. Thus, the multipath delay due to multipath delay amount and the second pseudorange difference value [Delta] [rho] ₃₁ according to the first pseudo-range differential value [Delta] [rho] ₂₁ matches, the multipath delay amount to be determined is approximately 60 m.

Using this principle, the multipath delay amount calculation unit 15 stores the pseudorange difference values Δρ ₂₁ and Δρ ₃₁ for the multipath delay amount in advance as a relation table. When the multipath delay amount calculation unit 15 acquires the first pseudo distance difference value Δρ ₂₁ and the second pseudo distance difference value Δρ ₃₁ , the multipath delay amount candidate corresponding to each pseudo distance difference value is obtained from the relation table. Are extracted, and multipath delay amounts that match at each pseudorange difference value are output. By making such a relationship table, it is possible to output the multipath delay amount at a higher speed than calculating the multipath delay amount every time the pseudorange difference value is acquired.

  At this time, the multipath delay amount calculation unit 15 corrects each pseudo-range difference value based on the amplitude ratio of the multipath state information and uses it for determining the multipath delay amount. This is based on the fact that the pseudorange changes according to the amplitude ratio between the direct wave signal and the indirect wave signal, and the relationship between the amplitude ratio and the correction value may be stored in a table. Then, by correcting the pseudo-range difference value based on the amplitude ratio in this way, it is not necessary to have a relationship table for each amplitude ratio, and resources for calculating the multipath delay amount can be saved.

  In the above description, the case where each process is executed for each functional block is shown. However, the process of these functional blocks is programmed and stored, and the program is executed by an arithmetic unit such as a CPU. May be. FIG. 3 is a diagram illustrating an execution flow of a program that performs multipath delay amount calculation processing. Note that the execution flow is a flow when the CPU performs the process performed by the above-described functional unit, and therefore, the description of each process will be simplified.

  First, an incoming signal is received and a received signal is acquired (S101). Next, a multipath state including the amplitude ratio between the direct wave signal and the indirect wave signal is detected based on the received signal (S102).

Next, the first pseudo distance ρ ₁ , the second pseudo distance ρ ₂ , and the third pseudo distance ρ ₃ are respectively calculated using the three sets of Early correlation processing signals and Late correlation processing signals (S103).

Next, the first pseudo distance difference value Δρ ₂₁ and the second pseudo distance difference value Δρ ₃₁ are calculated using the first pseudo distance ρ ₁ , the second pseudo distance ρ ₂ , and the third pseudo distance ρ ₃ (S104). .

Next, based on the amplitude ratio, the first pseudo distance difference value Δρ ₂₁ and the second pseudo distance difference value Δρ ₃₁ are corrected and normalized (S105).

Then, based on the first pseudo-range differential value [Delta] [rho] ₂₁ were normalized and the second pseudorange difference value [Delta] [rho] _31, from the relationship table between pseudorange difference value and the multi-path delay amount, determines a multi-path delay ( S106).

  As described above, by using the configuration and processing of this embodiment, the multipath delay amount can be calculated with higher accuracy than in the past. Further, by using such a highly accurate multipath delay amount, highly accurate positioning calculation can be performed.

  Next, a multipath detection device according to a second embodiment will be described with reference to the drawings. FIG. 4 is a block diagram illustrating a main configuration of a GNSS signal receiving apparatus 1A including the multipath detection apparatus according to the present embodiment. In FIG. 4, only the portions corresponding to the multipath detection device are shown. The GNSS signal receiving apparatus 1A according to the present embodiment is different from the GNSS signal receiving apparatus according to the first embodiment in the processing of the correlation processing signal generation unit 20A. The table is different. Therefore, only different points will be described.

  FIG. 5 is a waveform diagram of a BPSK correlation processing signal, a BOCcos subcarrier, a BOCcos correlation processing signal, a BOCmod subcarrier, and a BOCmod correlation processing signal.

Correlation signal generating unit 20A, like the correlation processing signal generator 20 of the first embodiment, Prompt correlation signal SR _P consisting of BPSK correlation processing signals, first, second 2Early correlation processing signal SR _E1 and SR _E2 , and first and second late correlation processing signals SR _L1 and SL _L2 are generated. The Prompt correlation processing signal is output to the P correlation unit 11. The first Early correlation processing signal SR _E1 and the first Late correlation processing signal SR _L1 are output to the E-L correlation unit 121. Second Early correlation processing signal SR _E2 and second Late correlation processing signal SL _L2 are output to EL correlation section 122.

  Further, the correlation processing signal generation unit 20A generates each of the following correlation processing signals including a BOCcos correlation processing signal obtained by multiplying the above-described BPSK correlation processing signal by the BOCcos subcarrier signal.

  Here, as shown in FIG. 5, the BOC cos subcarrier is a signal in which sign inversion occurs within one chip period of the BPSK correlation processing signal (replica signal). The BOC cos subcarrier is a signal that is at the Hi level over the period of 0.5 chip, centering on the intermediate timing (0.5 chip timing) of the 1 chip period, and is at the Low level during the other period. That is, the signal is a low level from the start timing of 1 chip to 0.25 chip, a high level from 0.25 chip to 0.75 chip, and a low level from 0.75 chip to 1.0 chip.

  As shown in FIG. 5, in the BOCcos correlation processing signal, the waveform of the BOCcos subcarrier appears as it is in the chip whose base BPSK correlation processing code is Hi, and the sign of the BPSK correlation processing signal is Low. In the chip, this is a signal that appears by inverting the waveform of the BOC cos subcarrier.

Correlation signal generating unit 20A is composed BOCcos correlation processing signals, around the timing the timing of the Prompt correlation processing signals SR _P, code phase interval (spacing) consists 1.0chip the 4Early correlation processing signal The SR _EC and the fourth late correlation processing signal SR _LC are generated.

The fourth Early correlation processing signal S R _EC and the fourth Late correlation processing signal SL _LC are output to the E-L correlation unit 123.

  The correlation process of the P correlation unit 11, the E-L correlation unit 121, and the E-L correlation unit 122, the pseudo distance calculation process of the pseudo distance calculation units 131 and 132, and the subtraction process of the adder 141 are the same as those in the first embodiment. It is the same as the processing shown.

E-L correlation unit 123 calculates a first 4Early correlation value by multiplying the first 4Early correlation processing signals _{SR EC} and the baseband signal _{S B.} E-L correlation unit 123 calculates a first 4Late correlation value by multiplying the first 4Late correlation processing signals _{SR LC} and the baseband signal _{S B.} The E-L correlation unit 123 subtracts the fourth Late correlation value from the fourth Early correlation value to calculate a fourth EL correlation value. The E-L correlation unit 123 integrates the fourth E-L correlation value for a predetermined time, calculates fourth code phase difference information, and outputs the fourth code phase difference information to the pseudo distance calculation unit 133.

The pseudo distance calculation unit 133 calculates the fourth pseudo distance ρ _C using the fourth code phase difference information based on the fourth E-L correlation value. The pseudo distance calculation unit 133 outputs the fourth pseudo distance ρ _C to the adder 142.

The adder 142 calculates a third pseudo distance difference value Δρ _C1 by subtracting the first pseudo distance ρ ₁ from the fourth pseudo distance ρ _C and outputs the third pseudo distance difference value Δρ _C1 to the multipath delay amount calculation unit 15.

The multipath delay amount calculation unit 15 calculates the multipath delay amount based on the first pseudo distance difference value Δρ ₂₁ and the third pseudo distance difference value Δρ _C1 . At this time, the multipath delay amount calculation unit 15 calculates the multipath delay amount with reference to the multipath state information.

  Specifically, the multipath delay amount calculation unit 15 calculates the multipath delay amount by the same processing as in the first embodiment. FIG. 6 is a diagram showing the characteristics of the pseudorange difference value with respect to the multipath delay amount when the multipath detection method according to the present embodiment is used.

6, a solid line indicates a transition of the first pseudorange difference value [Delta] [rho] ₂₁ to multipath delay, chain line indicates the transition of the third pseudorange difference value [Delta] [rho] _C1 to multipath delay. As shown in FIG. 6, the first pseudo-range differential value [Delta] [rho] ₂₁ in the third pseudorange difference value [Delta] [rho] _C1, transition state to multipath delay is different.

For example, in the case shown in FIG. 6, when the first pseudo distance difference value Δρ ₂₁ is about 30 m, the multipath delay amount is about 75 m or about 317 m. When the third pseudo distance difference value Δρ _C1 is about −42 m, the multipath delay amount is about 75 m. Thus, approximately 75m of the multipath delay due to multipath delay and a third pseudorange difference value [Delta] [rho] _C1 by the first pseudo-range differential value [Delta] [rho] ₂₁ match becomes the multipath delay amount to be determined.

  As described above, even when the configuration and processing of the present embodiment are used, the multipath delay amount can be calculated reliably and with high accuracy. Furthermore, if subcarriers are used as in the present embodiment, a variety of pairs of Early correlation processing signals and Late correlation processing signals can be configured. As a result, the characteristics of the pseudo-range difference value with respect to the multipath delay amount are diversified, and it is easy to set a combination that can more reliably detect the multipath delay amount.

  Next, a multipath detection device according to a third embodiment will be described with reference to the drawings. FIG. 7 is a block diagram illustrating a main configuration of a GNSS signal reception apparatus 1B including the multipath detection apparatus of the present embodiment. In FIG. 7, only the portions corresponding to the multipath detection device are shown. The processing of the correlation processing signal generation unit 20B is different from that of the GNSS signal reception device of the first and second embodiments in the GNSS signal reception device 1B of the present embodiment. The related table to be referenced is different. Therefore, only different parts will be described in detail.

Correlation signal generating unit 20B, similar to the correlation processing signal generator 20A of the second embodiment, Prompt correlation signal SR _P consisting of BPSK correlation processing signals, first, second 2Early correlation processing signal SR _E1 and SR _E2 , and first and second late correlation processing signals SR _L1 and SL _L2 are generated. The Prompt correlation processing signal is output to the P correlation unit 11. The first Early correlation processing signal SR _E1 and the first Late correlation processing signal SR _L1 are output to the E-L correlation unit 121. Second Early correlation processing signal SR _E2 and second Late correlation processing signal SL _L2 are output to EL correlation section 122.

  Further, the correlation processing signal generation unit 20B generates each of the following correlation processing signals including a BOCmod correlation processing signal obtained by multiplying the above-described BPSK correlation processing signal by the BOCmod subcarrier signal.

  Here, as shown in FIG. 5, the BOCmod subcarrier is a signal in which sign inversion occurs within one chip period of the BPSK correlation processing signal (replica signal). The BOCmod subcarrier is a signal that becomes Hi level for a predetermined chip period (for example, 0.25 chip period) around the intermediate timing (0.5 chip timing) of 1 chip period and becomes Low level in other periods. . That is, this signal is a low level from the start timing of 1 chip to 0.375 chip, a high level from 0.375 chip to 0.625 chip, and a low level from 0.625 chip to 1.0 chip. This state transition is an example, and other state transitions may be applied.

  As shown in FIG. 5, in the BOCmod correlation processing signal, the waveform of the BOCmod subcarrier appears as it is in the chip whose base BPSK correlation processing signal code is Hi, and the code of the BPSK correlation processing signal is Low. In the chip, the BOCmod subcarrier waveform is inverted and appears.

Correlation signal generating unit 20B is composed BOCmod correlation processing signals, around the timing the timing of the Prompt correlation processing signals SR _P, code phase interval (spacing) consists 1.0chip the 5Early correlation processing signal The SR _EM and the fifth Late correlation processing signal SR _LM are generated.

The 5Early correlation processing signals _{SR EM} and the 5Late correlation processing signals _{SL LM} is output to E-L correlator 123.

  The correlation process of the P correlation unit 11, the E-L correlation unit 121, and the E-L correlation unit 122, the pseudo distance calculation process of the pseudo distance calculation units 131 and 132, and the subtraction process of the adder 141 are the same as those in the first embodiment. It is the same as the processing shown.

E-L correlation unit 123 calculates a first 5Early correlation value by multiplying the first 5Early correlation processing signals _{SR EM} and the baseband signal _{S B.} E-L correlation unit 123 calculates a first 5Late correlation value by multiplying the first 5Late correlation processing signals _{SR LM} and the baseband signal _{S B.} The E-L correlation unit 123 subtracts the fifth Late correlation value from the fifth Early correlation value to calculate a fifth EL correlation value. The E-L correlation unit 123 integrates the fifth E-L correlation value for a predetermined time, calculates fifth code phase difference information, and outputs the fifth code phase difference information to the pseudo distance calculation unit 133.

The pseudo distance calculation unit 133 calculates the fifth pseudo distance ρ _M using the fifth code phase difference information based on the fifth E-L correlation value. The pseudo distance calculation unit 133 outputs the fifth pseudo distance ρ _M to the adder 142.

The adder 142 calculates the fourth pseudo distance difference value Δρ _M1 by subtracting the first pseudo distance ρ ₁ from the fifth pseudo distance ρ _M and outputs the fourth pseudo distance difference value Δρ _M1 to the multipath delay amount calculation unit 15.

The multipath delay amount calculation unit 15 calculates the multipath delay amount based on the first pseudo distance difference value Δρ ₂₁ and the fourth pseudo distance difference value Δρ _M1 . At this time, the multipath delay amount calculation unit 15 calculates the multipath delay amount with reference to the multipath state information.

  Specifically, the multipath delay amount calculation unit 15 calculates the multipath delay amount by the same processing as in the first embodiment. FIG. 8 is a diagram illustrating the characteristics of the pseudorange difference value with respect to the multipath delay amount when the multipath detection method according to the present embodiment is used.

8, a solid line indicates a transition of the first pseudorange difference value [Delta] [rho] ₂₁ to multipath delay, the two-dot chain line indicates a transition of the fourth pseudorange difference value [Delta] [rho] _M1 to multipath delay. As shown in FIG. 8, a first pseudorange difference value [Delta] [rho] ₂₁ In the fourth pseudorange difference value [Delta] [rho] _M1, transition state to multipath delay is different.

For example, in the case shown in FIG. 8, when the first pseudo-range difference value Δρ ₂₁ is about 25 m, the multipath delay amount is about 65 m or about 340 m. When the fourth pseudo-range difference value Δρ _M1 is about −12 m, the multipath delay amount is about 10 m or about 65 m. Thus, approximately 65m of the multipath delay due to multipath delay and a fourth pseudorange difference value [Delta] [rho] _M1 by the first pseudo-range differential value [Delta] [rho] ₂₁ match becomes the multipath delay amount to be determined.

  As described above, even when the configuration and processing of the present embodiment are used, the multipath delay amount can be calculated reliably and with high accuracy.

  Next, a multipath detection device according to a fourth embodiment will be described with reference to the drawings. FIG. 9 is a block diagram illustrating a main configuration of a GNSS signal receiving apparatus 1C including the multipath detection apparatus according to the present embodiment. In FIG. 9, only the portions corresponding to the multipath detection device are shown. The GNSS signal receiving apparatus 1C according to the present embodiment differs from the GNSS signal receiving apparatuses according to the first, second, and third embodiments in the processing of the correlation processing signal generation unit 20C, thereby calculating a multipath delay amount. The related table referred to by the unit 15 is different. Therefore, only different parts will be described in detail.

Correlation signal generating unit 20C, like the correlation processing signal generator 20 of the first embodiment, Prompt correlation signal SR _P consisting of BPSK correlation processing signals, the 1Early correlation processing signals _{SR E1,} and generating a second 1Late correlation processing signals _{SR L1.} The Prompt correlation processing signal is output to the P correlation unit 11. The first Early correlation processing signal SR _E1 and the first Late correlation processing signal SR _L1 are output to the E-L correlation unit 121.

Similarly to the correlation processing signal generation unit 20A of the second embodiment, the correlation processing signal generation unit 20C includes the fourth Early correlation processing signal SR _EC and the fourth Late correlation processing signal, which are BOC cos correlation processing signals. Generate SR _LC . The fourth Early correlation processing signal S R _EC and the fourth Late correlation processing signal SL _LC are output to the E-L correlation unit 123.

Moreover, the correlation processing signal generation unit 20C, like the correlation processing signal generator 20B of the third embodiment, the 5Early correlation processing signals _{SR EM} and the 5Late correlation processing signals consisting BOCmod correlation processing signal Create SR _LM . The 5Early correlation processing signals _{SR EM} and the 5Late correlation processing signals _{SL LM} is output to E-L correlator 123.

  The correlation process of the P correlation unit 11 and the E-L correlation unit 121 and the pseudo distance calculation process of the pseudo distance calculation unit 131 are the same as the processes shown in the first embodiment.

E-L correlation unit 122 calculates a first 4Early correlation value by multiplying the first 4Early correlation processing signals _{SR EC} and the baseband signal _{S B.} E-L correlation unit 123 calculates a first 4Late correlation value by multiplying the first 4Late correlation processing signals _{SR LC} and the baseband signal _{S B.} The E-L correlation unit 123 subtracts the fourth Late correlation value from the fourth Early correlation value to calculate a fourth EL correlation value. The E-L correlation unit 123 integrates the fourth E-L correlation value for a predetermined time, calculates fourth code phase difference information, and outputs the fourth code phase difference information to the pseudo distance calculation unit 132.

E-L correlation unit 123 calculates a first 5Early correlation value by multiplying the first 5Early correlation processing signals _{SR EM} and the baseband signal _{S B.} E-L correlation unit 123 calculates a first 5Late correlation value by multiplying the first 5Late correlation processing signals _{SR LM} and the baseband signal _{S B.} The E-L correlation unit 123 subtracts the fifth Late correlation value from the fifth Early correlation value to calculate a fifth EL correlation value. The E-L correlation unit 123 integrates the fifth E-L correlation value for a predetermined time, calculates fifth code phase difference information, and outputs the fifth code phase difference information to the pseudo distance calculation unit 133.

The pseudo distance calculation unit 132 calculates the fourth pseudo distance ρ _C using the fourth code phase difference information based on the fourth E-L correlation value. The pseudo distance calculation unit 132 outputs the fourth pseudo distance ρ _C to the adder 141.

The pseudo distance calculation unit 133 calculates the fifth pseudo distance ρ _M using the fifth code phase difference information based on the fifth E-L correlation value. The pseudo distance calculation unit 133 outputs the fifth pseudo distance ρ _M to the adder 142.

The adder 141 calculates the third pseudo distance difference value Δρ _C1 by subtracting the first pseudo distance ρ ₁ from the fourth pseudo distance ρ _C and outputs the third pseudo distance difference value Δρ _C1 to the multipath delay amount calculation unit 15.

The adder 142 calculates the fourth pseudo distance difference value Δρ _M1 by subtracting the first pseudo distance ρ ₁ from the fifth pseudo distance ρ _M and outputs the fourth pseudo distance difference value Δρ _M1 to the multipath delay amount calculation unit 15.

The multipath delay amount calculation unit 15 calculates the multipath delay amount based on the third pseudo distance difference value Δρ _C1 and the fourth pseudo distance difference value Δρ _M1 . At this time, the multipath delay amount calculation unit 15 calculates the multipath delay amount with reference to the multipath state information.

  Specifically, the multipath delay amount calculation unit 15 calculates the multipath delay amount by the same processing as in the first embodiment. FIG. 10 is a diagram illustrating the characteristics of the pseudorange difference value with respect to the multipath delay amount when the multipath detection method according to the present embodiment is used.

In FIG. 10, the one-dot chain line indicates the transition of the third pseudo-range difference value Δρ _C1 with respect to the multipath delay amount, and the two-dot chain line indicates the transition of the fourth pseudo-range difference value Δρ _M1 with respect to the multi-path delay amount. . As shown in FIG. 10, the third pseudorange difference value Δρ _C1 and the fourth pseudorange difference value Δρ _M1 have different transition states with respect to the multipath delay amount.

For example, in the case shown in FIG. 10, when the third pseudo-range difference value Δρ _C1 is about −30 m, the multipath delay amount is about 45 m or about 100 m. When the fourth pseudo-range difference value Δρ _M1 is about 5 m, the multipath delay amount is about 100 m, about 245 m, about 275 m, or about 420 m. Thus, about 100m to the multipath delay due to multipath delay and a fourth pseudorange difference value [Delta] [rho] _M1 according to a third pseudorange difference value [Delta] [rho] _C1 match becomes the multipath delay amount to be determined.

  As described above, even when the configuration and processing of the present embodiment are used, the multipath delay amount can be calculated reliably and with high accuracy. Furthermore, as shown in the present embodiment, by further increasing the signals from which the Early correlation processing signal and the Late correlation processing signal are generated, the characteristics of the pseudorange difference value with respect to the multipath delay amount are further diversified. It is easy to set a combination that can detect the multipath delay amount more reliably.

  In each of the above-described embodiments, an example is shown in which two pseudo-range difference values are calculated using three different early correlation processing signals and late correlation processing signals, and the multipath delay amount is calculated. However, if the number of pairs of Early correlation processing signals and Late correlation processing signals is three or more and the number of pseudo-range difference values is two or more, the multipath delay amount can be calculated similarly.

  Moreover, although the example using the BOCcos subcarrier and the BOCmod subcarrier as the subcarrier has been described in the above description, other subcarriers may be used. In the above description, an example in which one subcarrier cycle is superimposed on one chip of the BPSK correlation processing signal is shown. However, a plurality of subcarrier cycles are superimposed on one chip of the BPSK correlation processing signal. Thus, a correlation processing signal may be generated.

  Such a GNSS signal receiving apparatus and GNSS signal receiving function are used in a mobile terminal 300 as shown in FIG. FIG. 11 is a block diagram illustrating a main configuration of a mobile terminal 300 including the GNSS signal receiving apparatus 1 according to the present embodiment. Here, the GNSS signal receiving apparatus 1 will be described as an example, but the present invention can be similarly applied to the GNSS signal receiving apparatuses 1A, 1B, and 1C of other embodiments.

  A mobile terminal 200 as illustrated in FIG. 11 is, for example, a mobile phone, a car navigation device, a PND, a camera, a clock, and the like, and includes the GNSS signal reception device 1 and an application processing unit 300. The GNSS signal receiving apparatus 1 has the above-described configuration.

  Based on the positioning result output from the GNSS signal receiving apparatus 1, the application processing unit 300 displays the own apparatus position and the own apparatus speed, and executes processing for use in navigation and the like.

  In such a configuration, by obtaining the above-described highly accurate positioning result, highly accurate position display, navigation, and the like can be realized.

1, 1A, 1B, 1C: GNSS signal receiving device, 11: P correlation unit, 121, 122, 123: E-L correlation unit, 131, 132, 133: pseudorange calculation unit, 141, 142: adder, 15 : Multipath delay amount calculation unit, 20, 20A, 20B, 20C: correlation processing signal generation unit, 50: antenna, 51: RF processing unit, 52: multipath information detection unit, 53: carrier NCO, 54: baseband Conversion unit, 55: positioning calculation unit,
200: Mobile terminal, 300: Application processing unit

Claims (10)

A multipath detection method for detecting a multipath that occurs when a GNSS signal is received,
Based on the correlation processing signal having the spreading code of the GNSS signal, at least three pairs of early correlation processing signals and late correlation processing signals are respectively set with different code phase intervals or for correlation processing. A signal generation process for early late correlation processing generated by different codes;
A pseudo-range calculation step of performing a correlation process between each set of early correlation processing signal and late correlation processing signal and the received signal, and calculating a pseudo-range from each correlation processing result;
A pseudo-range difference value calculating step of calculating a pseudo-range difference value with a combination of different pseudo-ranges,
A multipath delay amount calculating step of calculating a multipath delay amount based on at least two pseudo-range difference values. The multipath detection method according to claim 1,
The pseudo-range difference value calculation step is a multipath detection method in which one pseudo-distance is set as a reference, and each pseudo-range difference value is calculated based on a difference with respect to the reference pseudo-range. The multipath detection method according to claim 1 or 2, wherein:
The early rate correlation processing signal generation step includes:
A multipath detection method, wherein a set of at least three early correlation processing signals and late correlation processing signals is generated using a single correlation processing signal with different code phase intervals. The multipath detection method according to claim 1 or 2, wherein:
A subcarrier generation step of generating a subcarrier to be superimposed on the correlation processing signal;
The early rate correlation processing signal generation step includes:
The at least three sets of early correlation processing signals and late correlation processing signals are divided into basic correlation processing signals generated from the spreading codes and subcarriers generated from spreading codes on which the subcarriers are superimposed. A multipath detection method, which is generated using a superposition type correlation processing signal. A multipath detection method according to any one of claims 1 to 4,
In the multipath delay amount calculation step, a relation table between the combination of the at least two pseudorange difference values and the multipath delay amount is stored in advance.
A multipath detection method for calculating a multipath delay amount using each calculated pseudorange difference value and the relation table. A multipath detection method according to any one of claims 1 to 5,
A multipath state detection step of detecting an amplitude ratio between a direct wave signal and an indirect wave signal of the GNSS signal that generates a multipath;
The multipath delay amount calculating step calculates the multipath delay amount in consideration of the amplitude ratio. A multipath detection program for causing a computer to execute a process of detecting a multipath that occurs when a GNSS signal is received,
Based on the correlation processing signal having the spreading code of the GNSS signal, at least three pairs of early correlation processing signals and late correlation processing signals are respectively set with different code phase intervals or for correlation processing. Signal generation processing for early late correlation processing generated by different codes,
A pseudo-distance calculation process for performing a correlation process between each set of early correlation processing signal and late correlation processing signal and the received signal, and calculating a pseudo-range from each correlation processing result;
A pseudo-range difference value calculation process for calculating a pseudo-range difference value by a combination of different pseudo-ranges,
And a multipath delay amount calculation process for calculating a multipath delay amount based on at least two pseudorange difference values. A multipath detection device for detecting a multipath generated when a GNSS signal is received,
Based on the correlation processing signal having the spreading code of the GNSS signal, at least three pairs of early correlation processing signals and late correlation processing signals are respectively set with different code phase intervals or for correlation processing. An early-late correlation processing signal generator that generates different codes;
A pseudo-range calculation unit that performs correlation processing between each set of early correlation processing signal and late correlation processing signal and the received signal, and calculates a pseudo-range from each correlation processing result;
A pseudo-range difference value calculating unit for calculating a pseudo-range difference value by a combination of different pseudo-ranges,
A multipath detection apparatus comprising: a multipath delay amount calculation unit that calculates a multipath delay amount based on at least two pseudorange difference values. A multipath detection device according to claim 8;
A GNSS signal receiving apparatus comprising: a positioning calculation unit that performs a positioning calculation using the pseudo distance and the multipath delay amount. GNSS signal receiving device according to claim 9,
A mobile terminal comprising: an application processing unit that executes a predetermined application using a positioning calculation result of the positioning calculation unit.

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