A weight determination method and system for weakening pseudorange and carrier multipath

Abstract

The present invention proposes a weighting method for weakening pseudorange and carrier multipath, which relates to the field of GNSS positioning technology, including: obtaining pseudorange observations and carrier observations; subtracting the pseudorange observations and the carrier observations and constructing a 2-fold first-order ionospheric delay coefficient, eliminating the 2-fold first-order ionospheric delay contained in the difference residual, obtaining a non-combined pseudorange multipath, and processing it by sliding window smoothing; extracting a weighting index of the pseudorange observations according to the smoothed pseudorange observations; extracting a weighting index of the carrier observations according to dual-frequency or higher carrier observations; determining the weights of each observation in the positioning algorithm according to the two weighting indexes, and completing the weighting process of weakening pseudorange and carrier multipath. The present invention also proposes a weighting system, which extracts the weighting index of the pseudorange observations and the weighting index of the carrier observations to determine the weights of each observation in the positioning algorithm, thereby weakening the influence of multipath on the accuracy of the final positioning result.

Description

Technical Field

[0001] The present invention relates to the field of GNSS positioning technology, and in particular to a weight determination method and system for weakening pseudorange and carrier multipath. Background Art

[0002] The global satellite navigation system GNSS is increasingly used in the field of precision positioning; GNSS observations include tropospheric and ionospheric delay errors, GLONASS FDMA signal frequency deviations, and multi-system GNSS positioning system deviations. In GNSS precision positioning, determining appropriate observation weights can effectively control the impact of various errors and improve positioning accuracy. The observation weighting methods currently used mainly include equal-precision weighting method, altitude angle weighting method, and signal-to-noise ratio weighting method. The altitude angle weighting method takes into account the characteristics that errors such as tropospheric and ionospheric delays and multipath effects on the satellite signal propagation path increase with decreasing altitude angles, and is easy to program and implement, so it has been widely used. The signal-to-noise ratio weighting method has been widely used in the case of severe multipath effects. The accuracy of satellite orbits and clock errors is also one of the important factors affecting GNSS precision positioning. For systems such as GPS, GLONASS, and Galileo, the accuracy of each satellite orbit and clock error is similar, and their influence is not considered when determining weights. However, the BeiDou satellite navigation system consists of three types of satellites at different altitudes: GEO, IGSO and MEO. The orbit and clock accuracy of each type of satellite varies greatly. Currently, the three-dimensional accuracy of GEO satellites reaches the meter level, the three-dimensional accuracy of IGSO is 20-30cm, and that of MEO is 10-20cm. For GPS / GLONASS / Galileo / BDS multi-system joint precision positioning, the satellite orbit and clock accuracy of different systems are also different. The current equal-precision weighting method, altitude angle weighting method, signal-to-noise ratio weighting method, etc. do not take into account the accuracy differences of satellite orbits and clock errors. Therefore, in the precision positioning of multiple orbit types and multiple GNSS systems, how to appropriately weight the observation values ​​to improve positioning accuracy has become an urgent problem to be solved.

[0003] However, in the study of existing public observation value weighting methods, it was found that multipath error is one of the main errors that lead to a decrease in positioning accuracy. Its variation is related to the environment and it is difficult to accurately eliminate it in a dynamic environment, which affects the improvement of positioning accuracy. Summary of the invention

[0004] In order to solve at least one of the above technical defects, the present invention provides a method and system for weakening pseudorange and carrier multipath weighting, by extracting pseudorange multipath as a weighting index of pseudorange observation value, and by extracting carrier frequency multipath as a weighting index of carrier observation value, so as to determine the weight of each observation value in the positioning algorithm, so as to achieve the purpose of weakening the influence of multipath on the accuracy of the final positioning result.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A weight determination method for weakening pseudorange and carrier multipath comprises the following steps:

[0007] S1: During the positioning process, obtain the pseudo-range observation value and carrier observation value of the ith frequency point without difference and combination;

[0008] S2: Subtract the pseudorange observation value from the carrier observation value, construct a 2x first-order ionospheric delay coefficient using dual-frequency or higher carrier observation values, eliminate the 2x first-order ionospheric delay contained in the residual difference between the pseudorange observation value and the carrier observation value, and obtain the non-combined pseudorange multipath;

[0009] S3: Eliminate the ambiguity and second-order ionospheric delay in the non-combined pseudorange multipath through sliding window smoothing to obtain the smoothed pseudorange observation value;

[0010] S4: extracting pseudo-range multipath according to the smoothed pseudo-range observation value as a weighting index of the pseudo-range observation value;

[0011] S5: extracting carrier frequency multipath according to the carrier observation values ​​of two or more frequencies as a weighting index of the carrier observation value;

[0012] S6: Determine the weight of each observation value in the positioning algorithm according to the weighting index of the pseudorange observation value and the weighting index of the carrier observation value, and complete the weighting process of weakening the pseudorange and carrier multipath.

[0013] In the above scheme, this scheme extracts pseudorange multipath as the weighting index of pseudorange observation value, and extracts carrier frequency multipath as the weighting index of carrier observation value, so as to determine the weight of each observation value in the positioning algorithm, thereby weakening the influence of multipath on the accuracy of the final positioning result and effectively improving the positioning accuracy.

[0014] Among them, in the step S1, the error components of the pseudo-range observation value and the carrier observation value of the non-differenced and non-combined i-th frequency point are:

[0015]

[0016]

[0017] Among them, P i represents the pseudorange observation value; L i represents the carrier observation value; f i Indicates frequency; represents the multipath of the carrier observation value, and its maximum value is Represents the carrier observation noise, which is generally smaller than the pseudorange observation noise Two orders of magnitude; ρ is the actual satellite-to-earth distance; c is the speed of light; dt r Indicates the receiver clock error; dt s represents the satellite clock error; T represents the tropospheric delay; A is the first-order ionospheric delay coefficient; B is the second-order ionospheric delay coefficient; N i represents the ambiguity of the carrier observation value;

[0018] In step S2, the pseudorange observation value and the carrier observation value are subtracted to obtain P i -L i , ignoring the multipath of the carrier observations and represents the carrier observation noise get:

[0019]

[0020] Among them, o means negligible; then, for dual-frequency or higher carrier observation values, the 2 times first-order ionospheric delay coefficient is specifically expressed as:

[0021]

[0022] in, represents the ionosphere-free combination; L1 represents the carrier observation value of frequency point 1; λ1 represents the wavelength of frequency point 1; N A Indicates fuzziness; ∈ A represents noise; n represents the number of frequency points, n≥2; a i represents the combination coefficient; D1 and D2 both represent intermediate variables; by combining equation (1) and equation (2), we get the non-combined pseudorange multipath expression, which is specifically expressed as:

[0023]

[0024]

[0025] in, Indicates multipath components; Bias i represents an item that does not change during the sliding window time. Eliminate when smoothing.

[0026] The implementation process of step S3 is specifically as follows:

[0027] For a window length of m, the Bias at the kth moment i，k , calculated using the following sliding average method, where Substituting into the following formula, the calculated E m (X k ) is Bias i，k , specifically:

[0028]

[0029]

[0030] in, Represents the multipath component at the kth moment; obtains the smoothed pseudorange observation value remember Pseudorange noise is and the carrier noise is Specifically expressed as:

[0031]

[0032]

[0033] in, represents the smoothed pseudorange observation noise;

[0034] In step S4, the smoothed pseudorange observation value noise is extracted to determine the multipath condition of the current pseudorange, and the weighted index of the pseudorange observation value is obtained by taking the inverse thereof.

[0035] In the above scheme, the double first-order ionospheric delay observation is constructed using the carrier observation values ​​of dual frequencies or more. To eliminate the difference P between pseudo-range carrier observations i -L i The residual contains twice the first-order ionospheric delay, and then the ambiguity and second-order ionospheric delay are eliminated through sliding window smoothing to extract the non-differenced and non-combined pseudorange multipath.

[0036] Among them, in the step S5, for the carrier observation values ​​of two or more frequencies, the i-th and j-th frequency points are taken as the inter-frequency single difference, where i≠j, so as to eliminate all the quantities that are independent of the frequency and have the same sign, and obtain:

[0037] L ij =L i -L j =-I ij +λ i N i -λ j N j +M ij +∈ ij

[0038] Among them, L ij Represents the single difference between frequency points i and j; I ij represents the single difference of ionospheric delay between frequencies i and j; N i N represents the ambiguity of the carrier observation value at frequency point i; jrepresents the ambiguity of the carrier observation value at frequency point j; M ij Represents the multipath frequency difference of frequency points i and j; ∈ ij represents the single-difference combined noise between frequencies i and j; where, due to the spatial correlation of ionospheric delay and its own characteristics, I ij changes slowly and is a constant term within a certain period of time; when the carrier observation value does not have a cycle slip, the ambiguity N i 、N j is a constant term; the operator for the difference between epochs is By eliminating the corresponding constant term through inter-epoch difference, the inter-frequency single-difference carrier multipath at the kth moment is obtained, which is specifically expressed as:

[0039]

[0040]

[0041] So far, we have obtained the carrier frequency multipath of the i-th and j-th frequencies at the k-th time. As a weighting indicator for carrier observation values.

[0042] Wherein, in step S6, the positioning algorithm is specifically expressed as:

[0043]

[0044]

[0045]

[0046] Among them, for the kth moment, K k is the gain matrix, H k is the observation model coefficient matrix, is the one-step forecast covariance matrix, is the state covariance matrix, is the one-step prediction state, is the state containing the position parameters, y k is a vector containing pseudorange and carrier observations; R k It is the observation noise matrix, and it is also the key matrix of the weighted index to weaken the multipath error and indirectly affect the positioning result. It is generated based on the pseudo-range noise and carrier noise Therefore, in the weighting process of weakening pseudorange and carrier multipath in step S6, when substituting pseudorange noise and carrier noise When additional and The jth frequency point only needs to satisfy j≠i; It represents the square of the weighted index of the pseudo-range observation value of the ith frequency point extracted at the kth time; It represents the square of the weighted index of the carrier observation value extracted at the i-th frequency point at the k-th time.

[0047] In the above solution, the positioning algorithm adopts the Kalman filtering algorithm.

[0048] The present invention also provides a weight determination system for weakening pseudorange and carrier multipath, which is used to implement a weight determination method for weakening pseudorange and carrier multipath, specifically comprising an observation value acquisition module, a non-combined pseudorange multipath calculation module, a smoothing processing module, a weight determination index extraction module and an observation value weight determination module; wherein:

[0049] The observation value acquisition module is used to obtain the non-difference non-combined pseudo-range observation value and carrier observation value of the i-th frequency point during the positioning process;

[0050] The non-combined pseudorange multipath calculation module is used to make a difference between the pseudorange observation value and the carrier observation value, and construct a 2 times first-order ionospheric delay coefficient using dual-frequency or higher carrier observation values, eliminate the 2 times first-order ionospheric delay contained in the difference residual between the pseudorange observation value and the carrier observation value, and obtain the non-combined pseudorange multipath;

[0051] The smoothing processing module eliminates the ambiguity and second-order ionospheric delay in the non-combined pseudorange multipath through sliding window smoothing to obtain a smoothed pseudorange observation value;

[0052] The weighted index extraction module is used to extract the pseudorange multipath as the weighted index of the pseudorange observation value according to the smoothed pseudorange observation value, and at the same time, extract the carrier frequency multipath as the weighted index of the carrier observation value according to the dual-frequency or more carrier observation value;

[0053] The observation value weight determination module is used to determine the weights of each observation value in the positioning algorithm according to the weight determination index of the pseudorange observation value and the weight determination index of the carrier observation value, and complete the weight determination process of weakening the pseudorange and carrier multipath.

[0054] Among them, in the observation value acquisition module, the error components of the pseudo-range observation value and the carrier observation value of the non-differenced and non-combined i-th frequency point are specifically expressed as follows:

[0055]

[0056]

[0057] Among them, P i represents the pseudorange observation value; L i represents the carrier observation value; f i Indicates frequency; represents the multipath of the carrier observation value, and its maximum value is Represents the carrier observation noise, which is generally smaller than the pseudorange observation noise Two orders of magnitude; ρ is the actual satellite-to-earth distance; c is the speed of light; dt r Indicates the receiver clock error; dt s represents the satellite clock error; T represents the tropospheric delay; A is the first-order ionospheric delay coefficient; B is the second-order ionospheric delay coefficient; N i represents the ambiguity of the carrier observation value;

[0058] In the non-combined pseudorange multipath calculation module, the pseudorange observation value and the carrier observation value are subtracted to obtain P i -L i , ignoring the multipath of the carrier observations and represents the carrier observation noise get:

[0059]

[0060] Among them, o means negligible; then, for dual-frequency or higher carrier observation values, the 2 times first-order ionospheric delay coefficient is specifically expressed as:

[0061]

[0062] in, represents the ionosphere-free combination; L1 represents the carrier observation value of frequency point 1; λ1 represents the wavelength of frequency point 1; N A Indicates fuzziness; ∈ A represents noise; n represents the number of frequency points, n≥2; α i represents the combination coefficient; D1 and D2 both represent intermediate variables; by combining equation (1) and equation (2), we get the non-combined pseudorange multipath expression, which is specifically expressed as:

[0063]

[0064]

[0065] in, Indicates multipath components; Bias i represents an item that does not change during the sliding window time. Eliminate when smoothing.

[0066] Among them, in the smoothing processing module, for a window length of m, the Bias at the kth moment i，k , calculated using the following sliding average method, where Substituting into the following formula, the calculated E m (X k ) is Biasi，k , specifically:

[0067]

[0068]

[0069] in, Represents the multipath component at the kth moment; obtains the smoothed pseudorange observation value remember Pseudorange noise is and the carrier noise is Specifically expressed as:

[0070]

[0071]

[0072] in, represents the smoothed pseudorange observation noise.

[0073] Among them, in the weighted index extraction module, the smoothed pseudorange observation value noise is extracted to judge the multipath situation of the current pseudorange, and the weighted index of the pseudorange observation value is obtained after taking the inverse thereof; at the same time, for the carrier observation values ​​of dual frequencies or more, the i-th and j-th frequency points are taken as the inter-frequency single difference, where i≠j, so as to eliminate all the quantities that are independent of the frequency and have the same sign, and obtain:

[0074] L ij =L i -L j =-I ij +λ i N i -λ j N j +M ij +∈ ij

[0075] Among them, L ij Represents the single difference between frequency points i and j; I ij represents the single difference of ionospheric delay between frequencies i and j; N i N represents the ambiguity of the carrier observation value at frequency point i; j represents the ambiguity of the carrier observation value at frequency point j; M ij Represents the multipath frequency difference of frequency points i and j; ∈ ij represents the single-difference combined noise between frequencies i and j; where, due to the spatial correlation of ionospheric delay and its own characteristics, I ij changes slowly and is a constant term within a certain period of time; when the carrier observation value does not have a cycle slip, the ambiguity N i 、Nj is a constant term; the operator for the difference between epochs is By eliminating the corresponding constant term through inter-epoch difference, the inter-frequency single-difference carrier multipath at the kth moment is obtained, which is specifically expressed as:

[0076]

[0077]

[0078] So far, we have obtained the carrier frequency multipath of the i-th and j-th frequencies at the k-th time. As a weighting indicator for carrier observation values.

[0079] Wherein, in the observation value weight determination module, the positioning algorithm is specifically expressed as:

[0080]

[0081]

[0082]

[0083] Among them, for the kth moment, K k is the gain matrix, H k is the observation model coefficient matrix, is the one-step forecast covariance matrix, is the state covariance matrix, is the one-step prediction state, is the state containing the position parameters, y k is a vector containing pseudorange and carrier observations; R k It is the observation noise matrix, and it is also the key matrix of the weighted index to weaken the multipath error and indirectly affect the positioning result. It is generated based on the pseudo-range noise and carrier noise Therefore, in the weight determination process of the observation value weight determination module to weaken the pseudorange and carrier multipath, when the pseudorange noise is substituted and carrier noise When additional and The jth frequency point only needs to satisfy j≠i; It represents the square of the weighted index of the pseudo-range observation value of the ith frequency point extracted at the kth time; It represents the square of the weighted index of the carrier observation value extracted at the i-th frequency point at the k-th time.

[0084] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0085] The present invention proposes a method and system for weighting pseudorange and carrier multipath, which extracts pseudorange multipath as a weighting index of pseudorange observation value, and extracts carrier frequency multipath as a weighting index of carrier observation value, so as to determine the weight of each observation value in the positioning algorithm, thereby achieving the purpose of weakening the influence of multipath on the accuracy of the final positioning result, and effectively improving the positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 It is a schematic diagram of the process of the method of the present invention;

[0087] Figure 2 A schematic diagram of a process of indirectly weakening multipath in one embodiment of the present invention;

[0088] Figure 3 This is a schematic diagram of the connection of the system modules of the present invention. DETAILED DESCRIPTION

[0089] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0090] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0091] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0092] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0093] Example 1

[0094] like Figure 1 As shown, a weight determination method for weakening pseudorange and carrier multipath includes the following steps:

[0095] S1: During the positioning process, obtain the pseudo-range observation value and carrier observation value of the ith frequency point without difference and combination;

[0096] S2: Subtract the pseudorange observation value from the carrier observation value, construct a 2x first-order ionospheric delay coefficient using dual-frequency or higher carrier observation values, eliminate the 2x first-order ionospheric delay contained in the residual difference between the pseudorange observation value and the carrier observation value, and obtain the non-combined pseudorange multipath;

[0097] S3: Eliminate the ambiguity and second-order ionospheric delay in the non-combined pseudorange multipath through sliding window smoothing to obtain the smoothed pseudorange observation value;

[0098] S4: extracting pseudo-range multipath according to the smoothed pseudo-range observation value as a weighting index of the pseudo-range observation value;

[0099] S5: extracting carrier frequency multipath according to the carrier observation values ​​of two or more frequencies as a weighting index of the carrier observation value;

[0100] S6: Determine the weight of each observation value in the positioning algorithm according to the weighting index of the pseudorange observation value and the weighting index of the carrier observation value, and complete the weighting process of weakening the pseudorange and carrier multipath.

[0101] In the specific implementation process, this embodiment extracts pseudorange multipath as a weighting indicator for pseudorange observation values, and extracts carrier frequency multipath as a weighting indicator for carrier observation values, so as to determine the weights of each observation value in the positioning algorithm, thereby weakening the impact of multipath on the accuracy of the final positioning result and effectively improving the positioning accuracy.

[0102] More specifically, in step S1, the error components of the pseudorange observation value and carrier observation value of the ith frequency point that are not differentially combined are:

[0103]

[0104]

[0105] Among them, P i represents the pseudorange observation value; L i represents the carrier observation value; f i Indicates frequency; represents the multipath of the carrier observation value, and its maximum value is Represents the carrier observation noise, which is generally smaller than the pseudorange observation noise Two orders of magnitude; ρ is the actual satellite-to-earth distance; c is the speed of light; dt r Indicates the receiver clock error; dt s represents the satellite clock error; T represents the tropospheric delay; A is the first-order ionospheric delay coefficient; B is the second-order ionospheric delay coefficient; N i represents the ambiguity of the carrier observation value;

[0106] In step S2, the pseudorange observation value and the carrier observation value are subtracted to obtain P i -L i , ignoring the multipath of the carrier observations and represents the carrier observation noise get:

[0107]

[0108] Among them, o means negligible; then, for dual-frequency or higher carrier observation values, the 2 times first-order ionospheric delay coefficient is specifically expressed as:

[0109]

[0110] in, represents the ionosphere-free combination; L1 represents the carrier observation value of frequency point 1; λ1 represents the wavelength of frequency point 1; N A Indicates fuzziness; ∈ A represents noise; n represents the number of frequency points, n≥2; a i represents the combination coefficient; D1 and D2 both represent intermediate variables; by combining equation (1) and equation (2), we get the non-combined pseudorange multipath expression, which is specifically expressed as:

[0111]

[0112]

[0113] in, Indicates multipath components; Bias i represents an item that does not change during the sliding window time. Eliminate when smoothing.

[0114] More specifically, the implementation process of step S3 is as follows:

[0115] For a window length of m, the Bias at the kth moment i，k , calculated using the following sliding average method, where Substituting into the following formula, the calculated E m (X k ) is Bias i，k , specifically:

[0116]

[0117]

[0118] in, Represents the multipath component at the kth moment; obtains the smoothed pseudorange observation value remember Pseudorange noise is and the carrier noise is Specifically expressed as:

[0119]

[0120]

[0121] in, represents the smoothed pseudorange observation noise;

[0122] In step S4, the smoothed pseudorange observation value noise is extracted to determine the multipath condition of the current pseudorange, and the weighted index of the pseudorange observation value is obtained by taking the inverse thereof.

[0123] In the specific implementation process, the double first-order ionospheric delay observation is constructed using the carrier observation values ​​of dual frequencies or more. To eliminate the difference P between pseudo-range carrier observations i -L i The residual contains twice the first-order ionospheric delay, and then the ambiguity and second-order ionospheric delay are eliminated through sliding window smoothing to extract the non-differenced and non-combined pseudorange multipath.

[0124] More specifically, in step S5, for the carrier observation values ​​of two or more frequencies, the i-th and j-th frequency points are taken as inter-frequency single differences, where i≠j, so as to eliminate all the quantities that are independent of the frequency and have the same sign, and obtain:

[0125] L ij =L i -L j =-I ij +λ i N i -λ j N j +M ij +∈ ij

[0126] Among them, L ij Represents the single difference between frequency points i and j; I ij represents the single difference of ionospheric delay between frequencies i and j; N i N represents the ambiguity of the carrier observation value at frequency point i; j represents the ambiguity of the carrier observation value at frequency point j; M ij Represents the multipath frequency difference of frequency points i and j; ∈ ij represents the single-difference combined noise between frequencies i and j; where, due to the spatial correlation of ionospheric delay and its own characteristics, I ij changes slowly and is a constant term within a certain period of time; when the carrier observation value does not have a cycle slip, the ambiguity N i 、N j is a constant term; the operator for the difference between epochs is By eliminating the corresponding constant term through inter-epoch difference, the inter-frequency single-difference carrier multipath at the kth moment is obtained, which is specifically expressed as:

[0127]

[0128]

[0129] So far, we have obtained the carrier frequency multipath of the i-th and j-th frequencies at the k-th time. As a weighting indicator for carrier observation values.

[0130] Example 2

[0131] More specifically, based on Example 1, the positioning algorithm is specifically expressed as follows:

[0132]

[0133]

[0134]

[0135] Among them, for the kth moment, K k is the gain matrix, H k is the observation model coefficient matrix, is the one-step forecast covariance matrix, is the state covariance matrix, is the one-step prediction state, is the state containing the position parameters, y k is a vector containing pseudorange and carrier observations; R k It is the observation noise matrix, and it is also the key matrix of the weighted index to weaken the multipath error and indirectly affect the positioning result. It is generated based on the pseudo-range noise and carrier noise As the basis.

[0136] Therefore, in the weighting process of weakening pseudorange and carrier multipath in step S6, the pseudorange multipath index of the i-th frequency point extracted at the k-th time is recorded as The carrier multipath index of the i-th and j-th frequency points is: Its participation indirectly weakens the multipath process such as Figure 2 As shown:

[0137] In general, the pseudorange and carrier observation noise matrix R is generated based on the pseudorange noise and carrier noise If we want to use this weighting method to weaken pseudorange and carrier multipath, we can substitute and When additional and The j-th frequency point only needs to satisfy j≠i.

[0138] In the specific implementation process, the positioning algorithm adopts the Kalman filtering algorithm.

[0139] Example 3

[0140] More specifically, Figure 3 As shown, this embodiment provides a weight determination system for weakening pseudorange and carrier multipath, which is used to implement a weight determination method for weakening pseudorange and carrier multipath, and specifically includes an observation value acquisition module, a non-combined pseudorange multipath calculation module, a smoothing processing module, a weight determination index extraction module and an observation value weight determination module; wherein:

[0141] The observation value acquisition module is used to obtain the non-difference non-combined pseudo-range observation value and carrier observation value of the i-th frequency point during the positioning process;

[0142] The non-combined pseudorange multipath calculation module is used to make a difference between the pseudorange observation value and the carrier observation value, and construct a 2 times first-order ionospheric delay coefficient using dual-frequency or higher carrier observation values, eliminate the 2 times first-order ionospheric delay contained in the difference residual between the pseudorange observation value and the carrier observation value, and obtain the non-combined pseudorange multipath;

[0143] The smoothing processing module eliminates the ambiguity and second-order ionospheric delay in the non-combined pseudorange multipath through sliding window smoothing to obtain a smoothed pseudorange observation value;

[0144] The weighted index extraction module is used to extract the pseudorange multipath as the weighted index of the pseudorange observation value according to the smoothed pseudorange observation value, and at the same time, extract the carrier frequency multipath as the weighted index of the carrier observation value according to the dual-frequency or more carrier observation value;

[0145] The observation value weight determination module is used to determine the weights of each observation value in the positioning algorithm according to the weight determination index of the pseudorange observation value and the weight determination index of the carrier observation value, and complete the weight determination process of weakening the pseudorange and carrier multipath.

[0146] Among them, in the observation value acquisition module, the error components of the pseudorange observation value and carrier observation value of the non-differenced and non-combined i-th frequency point are specifically expressed as follows:

[0147]

[0148]

[0149] Among them, P i represents the pseudorange observation value; L i represents the carrier observation value; f i Indicates frequency; represents the multipath of the carrier observation value, and its maximum value is Represents the carrier observation noise, which is generally smaller than the pseudorange observation noise Two orders of magnitude; ρ is the actual satellite-to-earth distance; c is the speed of light; dt r Indicates the receiver clock error; dt srepresents the satellite clock error; T represents the tropospheric delay; A is the first-order ionospheric delay coefficient; B is the second-order ionospheric delay coefficient; N i represents the ambiguity of the carrier observation value;

[0150] In the non-combined pseudorange multipath calculation module, the pseudorange observation value and the carrier observation value are subtracted to obtain P i -L i , ignoring the multipath of the carrier observations and represents the carrier observation noise get:

[0151]

[0152] Among them, o means negligible; then, for dual-frequency or higher carrier observation values, the 2 times first-order ionospheric delay coefficient is specifically expressed as:

[0153]

[0154] in, represents the ionosphere-free combination; L1 represents the carrier observation value of frequency point 1; λ1 represents the wavelength of frequency point 1; N A Indicates fuzziness; ∈ A represents noise; n represents the number of frequency points, n≥2; a i represents the combination coefficient; D1 and D2 both represent intermediate variables; by combining equation (1) and equation (2), we get the non-combined pseudorange multipath expression, which is specifically expressed as:

[0155]

[0156]

[0157] in, Indicates multipath components; Bias i represents an item that does not change during the sliding window time. Eliminate when smoothing.

[0158] Among them, in the smoothing processing module, for a window length of m, the Bias at the kth moment i，k , calculated using the following sliding average method, where Substituting into the following formula, the calculated E m (X k ) is Bias i，k , specifically:

[0159]

[0160]

[0161] in, Represents the multipath component at the kth moment; obtains the smoothed pseudorange observation value remember Pseudorange noise is and the carrier noise is Specifically expressed as:

[0162]

[0163]

[0164] in, represents the smoothed pseudorange observation noise.

[0165] Among them, in the weighted index extraction module, the smoothed pseudorange observation value noise is extracted to judge the multipath situation of the current pseudorange, and the weighted index of the pseudorange observation value is obtained after taking the inverse thereof; at the same time, for the carrier observation values ​​of dual frequencies or more, the i-th and j-th frequency points are taken as the inter-frequency single difference, where i≠j, so as to eliminate all the quantities that are independent of the frequency and have the same sign, and obtain:

[0166] L ij =L i -L j =-I ij +λ i N i -λ j N j +M ij +∈ ij

[0167] Among them, L ij Represents the single difference between frequency points i and j; I ij represents the single difference of ionospheric delay between frequencies i and j; N i N represents the ambiguity of the carrier observation value at frequency point i; j represents the ambiguity of the carrier observation value at frequency point j; M ij Represents the multipath frequency difference of frequency points i and j; ∈ ij represents the single-difference combined noise between frequencies i and j; where, due to the spatial correlation of ionospheric delay and its own characteristics, I ij changes slowly and is a constant term within a certain period of time; when the carrier observation value does not have a cycle slip, the ambiguity N i 、N j is a constant term; the operator for the difference between epochs is By eliminating the corresponding constant term through inter-epoch difference, the inter-frequency single-difference carrier multipath at the kth moment is obtained, which is specifically expressed as:

[0168]

[0169]

[0170] So far, we have obtained the carrier frequency multipath of the i-th and j-th frequencies at the k-th time. As a weighting indicator for carrier observation values.

[0171] Wherein, in the observation value weight determination module, the positioning algorithm is specifically expressed as:

[0172]

[0173]

[0174]

[0175] Among them, for the kth moment, K k is the gain matrix, H k is the observation model coefficient matrix, is the one-step forecast covariance matrix, is the state covariance matrix, is the one-step prediction state, is the state containing the position parameters, y k is a vector containing pseudorange and carrier observations; R k It is the observation noise matrix, and it is also the key matrix of the weighted index to weaken the multipath error and indirectly affect the positioning result. It is generated based on the pseudo-range noise and carrier noise Therefore, in the weight determination process of the observation value weight determination module to weaken the pseudorange and carrier multipath, when the pseudorange noise is substituted and carrier noise When additional and The jth frequency point only needs to satisfy j≠i; It represents the square of the weighted index of the pseudo-range observation value of the ith frequency point extracted at the kth time; It represents the square of the weighted index of the carrier observation value extracted at the i-th frequency point at the k-th time.

[0176] In the specific implementation process, the system is easy to build and simple to implement. By extracting pseudorange multipath as the weighting index of pseudorange observation value, and by extracting carrier frequency multipath as the weighting index of carrier observation value, the weight of each observation value in the positioning algorithm is determined, thereby weakening the influence of multipath on the accuracy of the final positioning result and effectively improving the positioning accuracy.

[0177] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A weighting method for weakening pseudorange and carrier multipath, characterized in that: The following steps are involved: S1: During the positioning process, obtain the pseudo-range observation value and carrier observation value of the ith frequency point without difference and combination; S2: Subtract the pseudorange observation value from the carrier observation value, construct a 2x first-order ionospheric delay coefficient using dual-frequency or higher carrier observation values, eliminate the 2x first-order ionospheric delay contained in the residual difference between the pseudorange observation value and the carrier observation value, and obtain the non-combined pseudorange multipath; S3: Eliminate the ambiguity and second-order ionospheric delay in the non-combined pseudorange multipath through sliding window smoothing to obtain the smoothed pseudorange observation value; S4: extracting pseudo-range multipath according to the smoothed pseudo-range observation value as a weighting index of the pseudo-range observation value; S5: extracting carrier frequency multipath according to the carrier observation values ​​of two or more frequencies as a weighting index of the carrier observation value; S6: Determine the weight of each observation value in the positioning algorithm according to the weighting index of the pseudorange observation value and the weighting index of the carrier observation value, and complete the weighting process of weakening the pseudorange and carrier multipath; Its expression is: Among them, for the kth moment, K k is the gain matrix, H k is the observation model coefficient matrix, is the one-step forecast covariance matrix, is the state covariance matrix, is the one-step prediction state, is the state containing the position parameters, y k is a vector containing pseudorange and carrier observations; R k It is the observation noise matrix, and it is also the key matrix of the weighted index to weaken the multipath error and indirectly affect the positioning result. It is generated based on the pseudo-range noise and carrier noise Based on, therefore, in the weighting process of weakening pseudorange and carrier multipath in step S6, Substituting the pseudorange noise and carrier noise When additional and The jth frequency point only needs to satisfy j≠i; It represents the square of the weighted index of the pseudo-range observation value of the ith frequency point extracted at the kth time; It represents the square of the weighted index of the carrier observation value extracted at the i-th frequency point at the k-th time.

2. A weight determination method for weakening pseudorange and carrier multipath according to claim 1, characterized in that: In step S1, the error components of the pseudorange observation value and carrier observation value of the ith frequency point that are not differentially combined are: Among them, P i represents the pseudorange observation value; L i represents the carrier observation value; f i Indicates frequency; represents the multipath of the carrier observation value, and its maximum value is Represents the carrier observation noise, which is generally smaller than the pseudorange observation noise Two orders of magnitude; ρ is the actual satellite-to-earth distance; c is the speed of light; dt r Indicates the receiver clock error; dt s represents the satellite clock error; T represents the tropospheric delay; A is the first-order ionospheric delay coefficient; B is the second-order ionospheric delay coefficient; N i represents the ambiguity of the carrier observation value; In step S2, the pseudorange observation value and the carrier observation value are subtracted to obtain P i -L i , ignoring the multipath of the carrier observations and represents the carrier observation noise get: Among them, o means negligible; then, for dual-frequency or higher carrier observation values, the 2 times first-order ionospheric delay coefficient is specifically expressed as: in, represents the ionosphere-free combination; L1 represents the carrier observation value of frequency point 1; λ1 represents the wavelength of frequency point 1; N A Indicates fuzziness; ∈ A represents noise; n represents the number of frequency points, n≥2; a i represents the combination coefficient; D1 and D2 both represent intermediate variables; by combining equation (1) and equation (2), we get the non-combined pseudorange multipath expression, which is specifically expressed as: in, Indicates multipath components; Bias i represents an item that does not change during the sliding window time. Eliminate when smoothing.

3. A weight determination method for weakening pseudorange and carrier multipath according to claim 2, characterized in that: The implementation process of step S3 is specifically as follows: For a window length of m, the Bias at the kth moment i，k , calculated using the following sliding average method, where Substituting into the following formula, the calculated E m (X k ) is Bias i，k , specifically: in, Represents the multipath component at the kth moment; obtains the smoothed pseudorange observation value remember Pseudorange noise is and the carrier noise is Specifically expressed as: in, represents the smoothed pseudorange observation noise; In step S4, the smoothed pseudorange observation value noise is extracted to determine the multipath condition of the current pseudorange, and the weighted index of the pseudorange observation value is obtained by taking the inverse thereof.

4. A method for determining weights for weakening pseudorange and carrier multipath according to claim 3, characterized in that: In step S5, for the carrier observation values ​​of two or more frequencies, the i-th and j-th frequency points are taken as inter-frequency single differences, where i≠j, so as to eliminate all the quantities that are independent of the frequency and have the same sign, and obtain: L ij =L i -L j =-I ij +λ i N i -l j N j +M ij +∈ ij Among them, L ij Represents the single difference between frequency points i and j; I ij represents the single difference of ionospheric delay between frequencies i and j; N i N represents the ambiguity of the carrier observation value at frequency point i; j represents the ambiguity of the carrier observation value at frequency point j; M ij Represents the multipath frequency single difference of frequency points i and j; ∈ ij represents the single-difference combined noise between frequencies i and j; where, due to the spatial correlation of ionospheric delay and its own characteristics, I ij It changes slowly and is a constant term within a certain period of time. When the carrier observation value does not have a cycle slip, the ambiguity N i 、N j is a constant term; the operator for the difference between epochs is By eliminating the corresponding constant term through inter-epoch difference, the inter-frequency single-difference carrier multipath at the kth moment is obtained, which is specifically expressed as: So far, we have obtained the carrier frequency multipath of the i-th and j-th frequencies at the k-th time. As a weighting indicator for carrier observation values.

5. A weight determination system for weakening pseudorange and carrier multipath, using the weight determination method for weakening pseudorange and carrier multipath according to any one of claims 1 to 4, characterized in that: It includes an observation value acquisition module, a non-combined pseudo-range multi-path calculation module, a smoothing processing module, a weighted index extraction module and an observation value weight determination module; wherein: The observation value acquisition module is used to obtain the non-difference non-combined pseudo-range observation value and carrier observation value of the i-th frequency point during the positioning process; The non-combined pseudorange multipath calculation module is used to make a difference between the pseudorange observation value and the carrier observation value, and construct a 2 times first-order ionospheric delay coefficient using dual-frequency or higher carrier observation values, eliminate the 2 times first-order ionospheric delay contained in the difference residual between the pseudorange observation value and the carrier observation value, and obtain the non-combined pseudorange multipath; The smoothing processing module eliminates the ambiguity and second-order ionospheric delay in the non-combined pseudorange multipath through sliding window smoothing to obtain a smoothed pseudorange observation value; The weighted index extraction module is used to extract the pseudorange multipath as the weighted index of the pseudorange observation value according to the smoothed pseudorange observation value, and at the same time, extract the carrier frequency multipath as the weighted index of the carrier observation value according to the dual-frequency or more carrier observation value; The observation value weight determination module is used to determine the weights of each observation value in the positioning algorithm according to the weight determination index of the pseudorange observation value and the weight determination index of the carrier observation value, and complete the weight determination process of weakening the pseudorange and carrier multipath.

6. A weight determination system for weakening pseudorange and carrier multipath according to claim 5, characterized in that: In the observation value acquisition module, the error components of the pseudorange observation value and carrier observation value of the non-differenced and non-combined i-th frequency point are specifically expressed as follows: Among them, P i represents the pseudorange observation value; L i represents the carrier observation value; f i Indicates frequency; represents the multipath of the carrier observation value, and its maximum value is Represents the carrier observation noise, which is generally smaller than the pseudorange observation noise Two orders of magnitude; ρ is the actual satellite-to-earth distance; c is the speed of light; dt r Indicates the receiver clock error; dt s represents the satellite clock error; T represents the tropospheric delay; A is the first-order ionospheric delay coefficient; B is the second-order ionospheric delay coefficient; N i represents the ambiguity of the carrier observation value; In the non-combined pseudorange multipath calculation module, the pseudorange observation value and the carrier observation value are subtracted to obtain P i -L i , ignoring the multipath of the carrier observations and represents the carrier observation noise get: Among them, o means negligible; then, for dual-frequency or higher carrier observation values, the 2 times first-order ionospheric delay coefficient is specifically expressed as: in, represents the ionosphere-free combination; L1 represents the carrier observation value of frequency point 1; λ1 represents the wavelength of frequency point 1; N A Indicates fuzziness; ∈ A represents noise; n represents the number of frequency points, V≥2; a i represents the combination coefficient; D1 and D2 both represent intermediate variables; by combining equation (1) and equation (2), we get the non-combined pseudorange multipath expression, which is specifically expressed as: in, Indicates multipath components; Bias i It means that it is an item that does not change during the sliding window time. Eliminate when smoothing.

7. A weight determination system for weakening pseudorange and carrier multipath according to claim 6, characterized in that: In the smoothing processing module, for a window length of m, the Bias at the kth moment i，k , calculated using the following sliding average method, where Substituting into the following formula, the calculated E m (X k ) is Bias i，k , specifically: in, Represents the multipath component at the kth moment; obtains the smoothed pseudorange observation value remember Pseudorange noise is and the carrier noise is Specifically expressed as: in, represents the smoothed pseudorange observation noise.

8. A weight determination system for weakening pseudorange and carrier multipath according to claim 7, characterized in that: In the weighted index extraction module, the smoothed pseudorange observation value noise is extracted to determine the multipath condition of the current pseudorange, and the weighted index of the pseudorange observation value is obtained after taking the inverse thereof; at the same time, for the carrier observation values ​​of dual frequencies or more, the i-th and j-th frequency points are taken as the inter-frequency single difference, where i≠j, so as to eliminate all the quantities that are independent of the frequency and have the same sign, and obtain: L ij =L i -L j =-I ij +λ i N i -l j N j +M ij +∈ ij Among them, L ij Represents the single difference between frequency points i and j; I ij represents the single difference of ionospheric delay between frequencies i and j; N i N represents the ambiguity of the carrier observation value at frequency point i; j represents the ambiguity of the carrier observation value at frequency point j; M ij represents the multipath frequency difference of frequency points i and j; ∈ij represents the frequency difference combined noise of frequency points i and j; where, due to the spatial correlation of ionospheric delay and its own characteristics, I ij It changes slowly and is a constant term within a certain period of time. When the carrier observation value does not have a cycle slip, the ambiguity N i 、N j is a constant term; the operator for the difference between epochs is By eliminating the corresponding constant term through inter-epoch difference, the inter-frequency single-difference carrier multipath at the kth moment is obtained, which is specifically expressed as: So far, we have obtained the carrier frequency multipath of the i-th and j-th frequencies at the k-th time. As a weighting indicator for carrier observation values.

9. A weight determination system for weakening pseudorange and carrier multipath according to claim 8, characterized in that: In the observation value weight determination module, the positioning algorithm is specifically expressed as: Among them, for the kth moment, K k is the gain matrix, H k is the observation model coefficient matrix, is the one-step forecast covariance matrix, is the state covariance matrix, is the one-step prediction state, is the state containing the position parameters, y k is a vector containing pseudorange and carrier observations; R k It is the observation noise matrix, and it is also the key matrix of the weighted index to weaken the multipath error and indirectly affect the positioning result. It is generated based on the pseudo-range noise and carrier noise Therefore, in the weight determination process of the observation value weight determination module to weaken the pseudorange and carrier multipath, when the pseudorange noise is substituted and carrier noise When additional and The jth frequency point only needs to satisfy j≠i; It represents the square of the weighted index of the pseudo-range observation value of the ith frequency point extracted at the kth time; It represents the square of the weighted index of the carrier observation value extracted at the i-th frequency point at the k-th time.

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