How to reject anomalous phase measurements and extend navigation solutions

Abstract

A method is described for rejecting anomalous phase measurements and extending navigation solutions and / or phase measurements. In a first variant, rapidly varying total phase (FP) portions are removed by subtracting calculations related to navigation satellite motion, receiver motion, and receiver time scale variations from the total phase. In this variant, slowly varying FPs (e.g., slow total phases) that are independent for different navigation satellites are isolated. These slow portions are then tracked by an individual loop (IL). The IL output signal is either a prediction or an estimation of those slow FPs. In a second variant, rapidly varying FP portions are tracked directly. The rapid FP variations are caused by navigation satellite, receiver motion, and receiver time scale variations.

Description

FIELD OF THE INVENTION

[0001] The present invention relates generally to the operation of navigation receivers, and more particularly to detecting anomalous measurements of a mobile navigation receiver (also known as a rover) and extending a navigation solution over a time interval to correct for the anomalous measurements.

[0002] A navigation receiver receives radio signals from multiple navigation satellites (NS). By processing these signals, a mobile receiver or rover determines the position and rate of movement of its antenna, i.e., it provides a position, velocity and timing (PVT) solution.

[0003] Under difficult rover operating conditions, for example, when radio signals are partially blocked and / or when there are strong multipath signals, anomalous signals with unacceptably large errors may appear and disrupt the rover's operation. If these anomalous measurements (anomalies) are not removed, they will cause unacceptably large errors in the PVT solution. What is needed is a robust PVT solution that provides accurate information despite the anomalies. Overview

[0004] According to one embodiment, a method for rejecting anomalous measurements and extending a navigation solution of a GNSS receiver includes calculating an estimated full phase (FP) of a tracked navigation satellite (NS) based on coordinate predictions of the GNSS receiver. Next, individual loop (IL) discriminator signals of the tracked NS are calculated. M number of NS discriminator signals are rejected and a corresponding flag is generated. A common loop (CL) discriminator signal is calculated based on K number of IL discriminator signals that are not rejected. Next, a current estimate of the coordinate and a GNSS receiver's time scale (RTS) are calculated. FP of the tracked NS is calculated based on the current estimate of the GNSS receiver's coordinate. Corrected IL discriminator signals are calculated for M number of NS. An estimate of integer ambiguity (IA) is calculated. A corrected IL discriminator signal based on the IA estimate is recalculated. An FP residual estimate is calculated. An SF signal is calculated based on the current estimate and prediction of the receiver coordinates, and then a prediction of the receiver coordinates is calculated.

[0005] According to one embodiment, a method for rejecting anomalous measurements and extending FP includes calculating an IL discriminator signal for a tracked NS. M number of IL discriminator signals for the NS are rejected and a corresponding flag is formed. A CL discriminator from the K non-rejected signals of the IL discriminator is then calculated. A corrected discriminator signal based on the CL discriminator signal is calculated. An FP estimate, Doppler frequency, and rate of change of Doppler frequency for the tracked NS are calculated to calculate an FP prediction, Doppler frequency, and rate of change of Doppler frequency for the tracked NS.

[0006] According to one embodiment, a method for generating an IL discriminator signal in a multi-frequency receiver for NS radiation signals in K frequency bands includes generating an IL discriminator signal for each frequency band f. determining the value obtained from TIFF2026506936000001.tif613 TIFF2026506936000002.tif613 is the threshold h snr The SNR of the jth NS in frequency band f is greater than the threshold h φ Less than The signal is checked based on the absolute value of TIFF2026506936000003.tif613. For TIFF2026506936000004.tif611, if one of the criteria is not met, the corresponding signal is rejected and a corresponding flag is generated. Using TIFF2026506936000005.tif726, we obtain the composite IL discriminator signal from the jth NS's unrejected L signal. TIFF2026506936000006.tif613 is formed, where an estimate of the energy potential of the fth signal, or another value that characterizes the value of the fth signal, can be used as the weight. In one embodiment, substituting the terms in the above formula gives the equation TIFF2026506936000007.tif1129 is generated.

[0007] Systems configured to perform the above-identified methods are also described herein. [Brief explanation of the drawings]

[0008] FIG. 1 illustrates a Global Navigation Satellite System (GNSS) receiver according to one embodiment.

[0009] FIG. 2 shows a block diagram of a buffer compensator block according to one embodiment.

[0010] FIG. 3 shows a block diagram of a buffer compensator block according to one embodiment.

[0011] FIG. 4 shows a flowchart of a method for rejecting anomalous measurements and extending the navigation solution of a GNSS receiver, according to one embodiment.

[0012] FIG. 5 shows a flowchart of a method for rejecting abnormal measurements and extending FP, according to one embodiment.

[0013] FIG. 6 shows a flowchart of a method for generating an IL discriminator signal in a multi-frequency receiver for NS radiation signals in the K frequency band, according to one embodiment.

[0014] 7 shows a high-level block diagram of a computer according to an embodiment.

[0015] In one embodiment, the receiver coordinate x i , y i , z i and NS coordinates (jth satellite) TIFF2026506936000008.tif43, TIFF2026506936000009.tif43, TIFF2026506936000010.tif43, Radius Range TIFF2026506936000011.tif43, receiver time scale q i and N-S time scale TIFF2026506936000012.tif45, wavelength λ, total phase (measured TIFF2026506936000013.tif43, residual TIFF2026506936000014.tif45, calculated TIFF2026506936000015.tif47, corrected TIFF2026506936000016.tif48), (Individual Loop TIFF2026506936000017.tif48 and common loop TIFF2026506936000018.tif45, corrected It should be noted that the discriminator output signal (in the case of TIFF2026506936000019.tif47) is measured in meters (m).

[0016] This document describes a method for rejecting anomalies that can cause errors in a position, velocity, and timing (PVT) solution. Additionally, a method for extending (e.g., extrapolating, extending) a PVT solution is also described. To obtain a PVT solution in a GNSS receiver, a least squares method (LSM) using satellite measurements (after rejecting anomalies) is typically used. More precisely, the LSM is typically used with the deviations of those measurements, rather than with predicted values ​​of those measurements. However, after a small number of measurements, the LSM stops functioning (no longer produces useful results), which leads to the need for extension. This problem does not occur if the LSM is replaced with Kalman filtering (KF), but such a replacement leads to significant computational complexity. Many methods have been proposed for performing extension without the computational complexity caused by the transition from LSM to KF, but each method has significant drawbacks. This document describes a different method for extension that does not suffer from the drawbacks of previously proposed methods.

[0017] Various algorithmic solutions are used to implement methods for anomaly rejection and PVT solution extension. These solutions share important characteristics. In one embodiment, the solutions are implemented by a buffer corrector (BC) in the GNSS receiver, operating as shown in the drawings and described below. This disclosure describes two BC variants:

[0018] In a first variant, rapidly varying total phase (FP) portions are removed by subtracting calculations related to navigation satellite motion, receiver motion, and receiver time scale variations from the total phase. In this variant, slowly varying FPs (e.g., slow total phases) that are independent for different navigation satellites are isolated. These slow portions are then tracked by an individual loop (IL). The IL output signal is either a prediction or an estimate of those slow FPs.

[0019] In a second variant, the rapidly varying FP portion is tracked directly, which is caused by the navigation satellite, the receiver motion, and the receiver time scale variations.

[0020] The following notations, terms and abbreviations are used in this specification:

[0021] Co-Op A conditional specification of a heuristic algorithm that uses both a common loop that tracks relatively fast, wideband effects common to all GNSS satellites (e.g., antenna phase center offset and receiver quartz variations), and individual loops that track relatively slow, narrowband effects specific to each satellite (e.g., frequency variations in a given satellite's onboard reference, atmospheric delays in signal propagation).

[0022] Single Parameter Co-Op This has only one common loop, specifically a quartz loop designed to track the receiver quartz standard frequency (phase), i.e., to track variations in the receiver time scale.

[0023] Multi-parameter Co-Op: This has at least three geometric common loops for tracking phase center motion along each of the three axes (e.g., along axes X, Y, Z in a geometric coordinate system, or along East, North, Up (E, N, U) in a local coordinate system) in addition to the common quartz loop.

[0024] Primary Co-Op: This is intended for the primary processing of the radio signal, i.e., carrier phase synchronization. In other embodiments, these tasks are performed by the phase-locked loop (PLL) or frequency-locked loop (FLL) of the carrier synchronization system, respectively. The tuning frequency of the tracking system in the primary processing is typically around 200-1000 Hz.

[0025] Second Order Co-Op This is intended to process FP measurements. In one embodiment, the regulation / control frequency in the IL and common loop is at least 5 Hz.

[0026] In this disclosure, only secondary Co-Ops are used, so the adjective "secondary" is omitted.

[0027] In one embodiment, the common loop and the individual loops include a discriminator and a loop filter.

[0028] In one embodiment of a multi-parameter Co-Op, there is one composite CL discriminator in the form of an LSM block for the IL discriminator signal. The composite signal at the output of this composite CL discriminator consists of four components, for example, according to the geometric coordinates X, Y, and Z, and according to the receiver time scale q. Thus, possibly, each output of each of the four common loop discriminators contains its own scalar signal based on the above mentioned coordinates.

[0029] In the single-parameter Co-Op case, only one CL discriminator signal is formed using a weighted sum of the IL discriminator signals by the receiver time scale q.

[0030] In one embodiment, a loop filter is used to generate the order of unstable behavior of CL and IL and the equivalent noise bandwidth of the corresponding loop.

[0031] In various embodiments, the Co-Op works with FPs or with FP function transforms. These FPs contain fast parts caused by NS motion, receiver motion, Earth rotation, and timescale variations. In addition, each FP contains slow parts caused by variations in NS timescales, atmospheric variations, and / or phase shift prediction errors due to NS motion. These slow effects are tracked by the IL.

[0032] The rapid portion of the FP (having a narrowband component) caused by the movement of the NS is unique to each NS, and the rapid portion can be calculated using ephemeris data and corrected based on the results of the calculation using the ephemeris.

[0033] The rapid part of the FP (with broadband components) due to receiver motion and time scale variations is caused by effects common to all satellites. In one embodiment, CL is used to track them.

[0034] Pseudo Measurements (PM) In this disclosure, there is a coordinate PM (CPM). The estimate of the antenna phase center (i.e., the three geometric coordinates) and the receiver time scale can be used as the CPM. The positioning algorithm processes both real measurements (RM) and PM together. In one embodiment, the RM is considered to have a larger weight and the PM is considered to have a smaller weight.

[0035] External Applications Applications that are external to the BC algorithm, such as smoothing filters (SF), navigation algorithms (RTK, DGPS, etc.), etc.

[0036] LSM One composite CL discriminator signal Least squares method to generate the four CL discriminator signals, which are components of TIFF2026506936000020.tif56.

[0037] Positioning algorithms such as RTK, PPP, and standalone can be used to determine various information along with BC.

[0038] BC-min An algorithm that operates based on data from one of the positioning algorithms once at the start or after recovery of the PVT solution, and then operates independently. Its primary purpose is to reject anomalies, and its secondary purpose is to extend the original navigation.

[0039] BC with one-sided weak integration BC with one-sided weak integration differs from BC-min only in the periodic corrections (approximately every 2-10 seconds) by the positioning algorithm, which leads to a significant improvement in extension accuracy due to the reduced extension time.

[0040] Using weak integration, BC is calculated by the equation It is corrected periodically (for example, every 2 seconds or after recovery of the navigation solution) according to the navigation algorithm data used as shown in TIFF2026506936000021.tif524.

[0041] BC with Bilateral Weak Integration BC with bilateral weak integration differs from BC with unilateral weak integration only in that it outputs a health flag from the raw data to the positioning algorithm. This flag is used as an additional catcher during positioning.

[0042] Using double-sided weak integration, the BC generates a signal to reject anomalous FP measurements and initially to reject tracking of the reflected signal in situations where the amplitude of the reflected signal is larger than the amplitude of the direct signal.

[0043] Epoch The time interval by which measurements are received by the BC.

[0044] Step Epoch Number

[0045] FIG. 1 shows a GNSS receiver 101 according to one embodiment. The GNSS receiver 101 can be located on a rover and can be mobile (referred to as a mobile receiver). Radio signals emitted by GNSS satellites are received by an antenna 102 and then processed by an RF section 111 of the GNSS receiver 101. The output of the RF section 111 is input to an ADC 110, where it is converted to a digital signal. A digital reading of the correlation component is output from the ADC and input to a primary processing block 103, which performs primary processing of the received signal. The primary processing block 103 measures the total phase (FP) of the carrier of the received NS signal, the code delay of the received NS signal, measures the signal-to-noise ratio (SNR), and also processes information transmitted from the satellites (e.g., ephemeris information). These measurements and received information are input to a secondary processing block 104, which uses the measurements and received information to solve navigation tasks. The secondary processing block 104 estimates the position and / or velocity of the mobile receiver (i.e., the antenna of the mobile receiver) and outputs the estimate via line 105. Output.

[0046] In one embodiment, the data output by the secondary processing block 104 is input to a buffer corrector block 106 (also referred to as BC block 106 or BC106), which detects anomalous measurements and outputs appropriate flags back to the secondary processing block 104. Two different embodiments of the implementation of the BC block 106 are described herein. Both embodiments use a second-order multi-parameter Co-Op.

[0047] 2 shows a block diagram of a first embodiment in which the second-order Co-Op and navigation solution extension is implemented in the BC block 106. In this embodiment, the BC block 106 uses second-order Co-Op bilateral weak integration and FP integer correction. According to this embodiment, the BC block 106 receives information from the secondary processing block 104 and operates as described below.

[0048] In the i-th step of the algorithm for M observed NS (i.e., the number of navigation satellites from which the mobile receiver receives signals), the following value is determined: Measured FPφ defined using TIFF2026506936000022.tif645 i Value for 202 TIFF2026506936000023.tif637 is determined and output from the secondary processing block 104, and the equation Residual prediction of FP defined using TIFF2026506936000024.tif645 TIFF2026506936000025.tif56204 was determined, and the equation Signal-to-noise ratio (dB-Hz) SNR defined using TIFF2026506936000026.tif650 i 206 is output from the secondary processing block 104.

[0049] Using the ephemeris information, the coordinates of the jth NS (coordinates TIFF2026506936000027.tif621) and the time scale drift of NS for the current epoch i. TIFF2026506936000028.tif67 is calculated at the time of signal emission.

[0050] The calculated coordinates of NS and the equation Coordinates calculated using TIFF2026506936000029.tif524 Using the a priori estimate of the receiver coordinates, which are estimates of TIFF2026506936000030.tif54208, the pseudorange a priori is calculated using the equation

number

[0051] Earth's rotation TIFF2026506936000032.tif68, Tropospheric Delay TIFF2026506936000033.tif610 and ionospheric delay The calculated FP including correction for TIFF2026506936000034.tif69 is calculated using the following equation:

number

[0052] A column vector of FP residuals is formed, which is expressed as

number

[0053] For all NSs, the signal of the IL discriminator is given by the equation

number

[0054] The value obtained in the rejection block 244 of FIG. TIFF2026506936000041.tif611 has two criteria, namely, the jth NS TIFF2026506936000042.tif69 is the threshold h snr =10 dB Hz or greater, and modulo operation TIFF2026506936000043.tif510 is the threshold h φ= 0.08 m, which is checked for reliability.

[0055] signal If one of the criteria is not met for TIFF2026506936000044.tif611, the corresponding signal is rejected. A corresponding reject flag is generated in the reject block 244 and sent to the secondary processing block 104.

[0056] The set of N non-rejected signals of the discriminator (shown in Equation 4) is given by Equation 1 for the LSM. IL discriminator defined using TIFF2026506936000045.tif558 Construct a vector of signals from TIFF2026506936000046.tif59.

[0057] Using the LSM algorithm, the CL discriminator The signal in TIFF2026506936000047.tif56212 is expressed as

number

number

[0058] In one embodiment where the navigation solution does not degrade with total loss of all NS tracking, a variant of LSM using coordinate PM (CPM) is used. Furthermore, CPM allows the estimate TIFF2026506936000054.tif56212 is implicitly smoothed. In one embodiment, the degree of smoothing is determined by the CPM weight. In one embodiment, by default, the CPM weight W KPI = 500 (which corresponds to a standard deviation of the prior coordinate prediction error of 0.044 m). When used as a point for linearized PM, the estimated value TIFF2026506936000055.tif529 is always equal to 0, i.e., for j=N+1, …, N+4, TIFF2026506936000056.tif617. In one embodiment, the following equation

number

[0059] Receiver coordinate estimates and receiver time scale drift TIFF2026506936000061.tif54218 is the equation TIFF2026506936000062.tif527, and any particular time is defined using the equation

number

number

[0060] The column vector of differences between observed and calculated estimates of FP is given by the equation

number

[0061] IL discriminator correction signal TIFF2026506936000076.tif57224 is the equation

number

[0062] IL discriminator correction signal TIFF2026506936000078.tif58 is the threshold hφ The signal is compared to the threshold. If the bounds defined by the equation are exceeded, an integer correction is performed, i.e., the estimate of the integer ambiguity (IA) is corrected by the equation

number

number

[0063] In equation 12, floor{} is the operation of rounding up to the previous integer, and in equation 13, The operation replaces the original value with a new value, as shown by TIFF2026506936000082.tif533.

[0064] For signals containing bit information (i.e., data signals), the IA correction is a multiple of 0.5 cycles (0.5λ). For signals without bit information (i.e., pilot signals), the IA is a multiple of 1 cycle (λ).

[0065] Next, predict the FP residuals TIFF2026506936000083.tif540 is calculated for step (i+1) and the equation

number

[0066] In one embodiment, the NS measurement is calculated based on the IL discriminator signal If a vector of TIFF2026506936000085.tif59 is formed, it is rejected. In one embodiment, in the case of loss of tracking NS signal, an IA estimate (Equation 12) and a residual prediction (Equation 14) are generated.

[0067] Coordinate estimates, and equations Receiver time scale defined using TIFF2026506936000086.tif529 After TIFF2026506936000087.tif54218 is formed based on the set of signals of the IL discriminator, the equation Smoothed coordinate estimates defined using TIFF2026506936000088.tif532 TIFF2026506936000089.tif54230 and the equation TIFF2026506936000090.tif535Velocity defined using TIFF2026506936000091.tif54232 and the equation TIFF2026506936000092.tif536 Acceleration defined using TIFF2026506936000093.tif54234 is calculated in the smoothing filter block 250 using a smoothing filter. When applied to a theoretical coordinate (i.e., one of the x, y, z, q coordinates), the smoothed estimate is given by the formula

number

number

[0068] For the smoothing filter at receiver time scale q, the coefficients K1, K2 and K3 are calculated as follows: TIFF2026506936000103.tif717TIFF2026506936000104.tif716K3=0 and z=15

[0069] equation Coordinates defined by TIFF2026506936000105.tif529 Prediction, equation for TIFF2026506936000106.tif54208 Speed ​​defined by TIFF2026506936000107.tif535 TIFF2026506936000108.tif54236 and equation Acceleration defined by TIFF2026506936000109.tif536 TIFF2026506936000110.tif54238 is calculated based on the smoothed estimate of SF (shown in Equation 15). Specifically, for a theoretical coordinate t (i.e., one of the coordinates x, y, z, q),

number

[0070] Thus, a prediction is calculated in extension block 252 in step i-1 and stored in delay blocks 254, 256, 258 shown in FIG. 2 for use in step i.

[0071] The initialization and restart of the buffer compensator 106 is as follows.

[0072] An initialization is performed the first time the BC 106 is turned on, and a restart is performed if the PVT solution is lost.

[0073] When initializing or restarting the BC106, the following conditions must be met: There is a relatively accurate PVT solution (RTK, PPP, etc., and the RMS estimate of the coordinate estimation error is less than 0.04 m). Signals are received from at least a certain number of NSs (e.g., six or more). The estimated accuracy of the available PVT solution is higher than a certain accuracy (i.e., the RMS estimate of the coordinate estimation error is less than 0.04 m).

[0074] If these conditions are met, the initialization or restart will proceed as follows: TIFF2026506936000114.tif526 and TIFF2026506936000115.tif526 is the current coordinate estimate of the navigation solution. Step set in TIFF2026506936000116.tif424, receiver time scale estimate TIFF2026506936000117.tif54 is set to receiver time scale (RTS) q0, step speed TIFF2026506936000118.tif538 is the current estimate of the PVT solution The step is set to TIFF2026506936000119.tif538, and the integer correction estimate is set to zero, i.e., This is done using the steps in TIFF2026506936000120.tif617.

[0075] The initial residuals are given by the equation

number

[0076] In one embodiment, the BC correction is performed every 2 seconds as follows:

[0077] For BC correction, the same conditions as for initialization and restart must be met: a relatively accurate navigation solution (RTK, PPP, etc.) is available, signals are received from at least a certain number of NSs (e.g., six or more), and the estimated accuracy of the available PVT solution is higher than a certain accuracy (i.e., the RMS estimate of the coordinate estimation error is less than 0.04 m).

[0078] If the above conditions are met, the correction is performed as follows: BC coordinates TIFF2026506936000124.tif524 and TIFF2026506936000125.tif524 is the current estimate of the PVT solution TIFF2026506936000126.tif422, and the integer correction estimate is zero, i.e., It is set to TIFF2026506936000127.tif617.

[0079] In one embodiment, tracking of a new NS is performed as follows: At the start of tracking of a new jth NS, an estimate of the integer correction TIFF2026506936000128.tif610 is set to zero and the residual is calculated according to Equation 18.

[0080] In one embodiment, a reject flag is generated for external applications in response to anomalous measurements. In the case of two-sided weak integration, it is necessary to introduce a mechanism for external applications to reject NS measurements (an additional mechanism related to the rejections already allowed). In one embodiment, the condition name "Peak Detector" (also called Peak D) is used.

[0081] In one embodiment, peak D is required in BC because integer corrections are performed, and the FP reject flag is set for only one epoch. For anomalies related to a single FP jump / slip, this approach is acceptable. However, in the case of reflected signal tracking (RST), the FP reject flag is periodic; that is, while the reject flag is generated during integer corrections, when integer corrections are performed, the reject flag is reset without detecting an anomaly.

[0082] The following algorithm is for rejecting anomalous FP measurements (in one embodiment, the entire RST) for external application peak D. In one embodiment, peak D of the test signal for the jth NS generated in the previous epoch TIFF2026506936000129.tif66 is the equation

number

[0083] In one embodiment, Current estimates TIFF2026506936000132.tif64 follows the rules

number

[0084] The signal (Equation 20) is filtered to the outer rejection threshold h φ If it exceeds, the FP external reject flag is set.

[0085] To reduce the rejection delay time in case of very large FP slips, the maximum signal value TIFF2026506936000135.tif32 is Only TIFF2026506936000136.tif719 is limited. Furthermore, when adding a new NS, The file is TIFF2026506936000137.tif610.

[0086] In various embodiments, the Peak D algorithm can be implemented for different frequency ranges.

[0087] It should be noted that multiple adders 248, 260, 262, 264, 266, 268 and 270 are used to sum the inputs to each adder.

[0088] Figure 3 shows a block diagram of a second embodiment in which second-order co-op and FP extension of the navigation solution are implemented in the BC block 106. In this embodiment, BC-min with bilateral weak integration based on second-order co-op with integer FP correction is described.

[0089] The difference between the embodiment shown in FIG. 3 and the embodiment shown in FIG. 2 is that in the embodiment shown in FIG. 2, the PVT solution and the FP residual are extended, while in the embodiment shown in FIG. 3, the FP is extended.

[0090] In the i-th step of the algorithm for M observed NS cases, at the output of the secondary processing block 104, the equation FPφ defined using TIFF2026506936000138.tif636 i 302 at the output of delay block 334, the equation FP prediction defined using TIFF2026506936000139.tif636 TIFF2026506936000140.tif54312, and at the output of the secondary processing block 104, the equation Signal-to-noise ratio (SNR) defined using TIFF2026506936000141.tif650 i 304 was observed.

[0091] For each tracked NS, the difference between the observed and predicted FP is calculated, i.e., Eq.

number

[0092] equation IL discriminator signal defined using TIFF2026506936000143.tif546 Vector of TIFF2026506936000144.tif59.

[0093] The value obtained in the rejection block 324 TIFF2026506936000145.tif611 has two criteria, namely, the jth NS TIFF2026506936000146.tif69 is h snr greater than (for example, 10 dB Hz), and the value obtained by modulo arithmetic TIFF2026506936000147.tif611 is the threshold h φ It is confirmed that the distance is smaller than (for example, 0.08 m).

[0094] signal If one of the above criteria is not met for TIFF2026506936000148.tif611, the corresponding signal is rejected. A reject flag 326 is generated by the reject block 324 and output to the secondary processing block 104.

[0095] N unrejected signals IL discriminator signal using TIFF2026506936000149.tif611 The vector TIFF2026506936000150.tif545 is generated, and the CL discriminator signal is given by the equation

number

[0096] Next, the four-dimensional vector TIFF2026506936000157.tif56 is projected onto the satellite's line of sight. The resulting correction signal The M direction vector of TIFF2026506936000158.tif57 is given by the equation

number

number

[0097] Here, CL TIFF2026506936000166.tif54, TIFF2026506936000167.tif54, Coefficients and IL of TIFF2026506936000168.tif54 TIFF2026506936000169.tif57, TIFF2026506936000170.tif57, The coefficients of TIFF2026506936000171.tif57 are given by the equation

number

[0098] In one embodiment, in Equation 25, k=3 for the CL coefficient and k=27 for the IL coefficient.

[0099] The prediction formula for step i (generally for the third floor) is:

number

[0100] In one embodiment, the initialization of the BC 106 of Figure 3 is as follows: When the BC starts, the current receiver coordinates FP calculated based on TIFF2026506936000178.tif526 TIFF2026506936000179.tif610 is used to calculate the IL discriminator signal of the jth NS, FP Used as a prediction for TIFF2026506936000180.tif65.

[0101] In one embodiment, this means that the coordinates of the jth NS at the time of signal emission (coordinates TIFF2026506936000181.tif614) and the NS time scale drift for the current epoch using ephemeris information. TIFF2026506936000182.tif67 and the estimated a priori pseudoranges based on the calculated coordinates of the NS and the geometric coordinates (x0, y0, z0) of the receiver are calculated using the equation

number

[0102] The calculated FP is the rotation of the Earth TIFF2026506936000184.tif69, Tropospheric Delay TIFF2026506936000185.tif611 and ionospheric delay TIFF2026506936000186.tif69, receiver time scale drift q0, and NS time scale drift Including corrections taking into account TIFF2026506936000187.tif67, the equation

number

[0103] Then, for NSj, the equation

number

[0104] After initialization, the BC 106 operates as described above in connection with FIG.

[0105] In one embodiment, when a new NS signal is provided to the BC 106, the IL discriminator signal for the new NS signal is calculated according to Equation 29.

[0106] The buffer compensator operating as described above was considered to function using a single frequency measurement. In one embodiment, the method for generating an IL discriminator signal for a multi-frequency receiver is as follows.

[0107] The NS in modern navigation systems emits radio signals simultaneously in several frequency ranges. Therefore, the CL discriminator signal It is important to use their joint processing to calculate TIFF2026506936000191.tif643.

[0108] In one embodiment, joint processing is used for NSs that radiate signals in, for example, K frequency bands.

[0109] In this embodiment, in the ith step for the jth NS, K measured FPs TIFF2026506936000192.tif619 and K prediction TIFF2026506936000193.tif619 (or FP residual estimates TIFF2026506936000194.tif623).

[0110] The IL discriminator signal is given by the equation TIFF2026506936000195.tif634 or TIFF2026506936000196.tif637 is used to determine for each frequency band.

[0111] Obtained value TIFF2026506936000197.tif613 has two criteria: threshold h snr The SNR of the jth NS in frequency band f is greater than the threshold h φ is smaller than It is confirmed according to the absolute value of TIFF2026506936000198.tif613.

[0112] signal If one of the above criteria is not met for TIFF2026506936000199.tif613, the corresponding signal is rejected. A corresponding reject flag 326 is generated by the reject block 324 and sent to the secondary processing block 104 shown in FIG.

[0113] Composite IL discriminator signal TIFF2026506936000200.tif611 is the equation

number

[0114] The composite signal of the IL discriminator signal (Equation 31) is used in BC to calculate the signal of the CL discriminator. Further operations in BC remain unchanged compared to the single frequency case.

[0115] It should be noted that multiple adders 336, 338, 340, 342, 344, 346, 348 and 350 are used to sum the inputs to each adder.

[0116] FIG. 4 shows a flowchart of a method 400 for rejecting anomalous measurements and extending a navigation solution of a GNSS receiver, according to one embodiment. In step 402, a calculated total phase (FP) for a tracked navigation satellite (NS) is calculated based on the GNSS receiver's coordinate prediction. In step 404, an IL discriminator signal for the tracked NS is calculated. In step 406, M number of NS discriminator signals are rejected and a corresponding flag is generated. In step 408, a CL discriminator signal is calculated based on K number of IL discriminator signals that were not rejected. In step 410, a current estimate of the coordinate and a time scale (RTS) for the GNSS receiver are calculated. In step 412, the FP for the tracked NS is calculated as a current estimate of the GNSS receiver's coordinate. In step 414, a corrected IL discriminator signal for M number of NS is calculated. In step 416, an estimate of the integer ambiguity (IA) is calculated. In step 418, a corrected IL discriminator signal based on the IA estimate is recalculated. In step 420, an FP residual estimate is calculated. In step 422, an SF signal based on the current estimate and prediction of the receiver coordinates is calculated. In step 424, a prediction of the receiver coordinates is calculated.

[0117] FIG. 5 shows a flowchart of a method 500 for rejecting anomalous measurements and extending FP, according to one embodiment. In step 502, an IL discriminator signal of the tracked NS is calculated. In step 504, M number of IL discriminator signals of the NS are rejected and a corresponding flag is formed. In step 506, a CL discriminator from the K non-rejected signals of the IL discriminators is calculated. In step 508, a corrected discriminator signal based on the CL discriminator signal is calculated. In step 510, an FP estimate, Doppler frequency, and rate of change of Doppler frequency of the tracked NS are calculated. In step 512, an FP prediction, Doppler frequency, and rate of change of Doppler frequency of the tracked NS are calculated.

[0118] 6 shows a flowchart of a method 600 for generating an IL discriminator signal in a multi-frequency receiver for NS emitted signals in K frequency bands, according to one embodiment. In step 602, an IL discriminator signal for each frequency band f is generated. TIFF2026506936000202.tif613 is determined. In step 604, the obtained value TIFF2026506936000203.tif613 is the threshold h snr The SNR of the jth NS in frequency band f is greater than the threshold h φ Less than TIFF2026506936000204.tif613. For TIFF2026506936000205.tif613, if one of the criteria is not met, the corresponding signal is rejected and a corresponding flag is generated. TIFF2026506936000206.tif611 is the equation TIFF2026506936000207.tif1129 is used to form the L j-th NS non-rejected signals.

[0119] Any of the components, operations, or methods illustrated in Figures 1-6 may be implemented using a computer. A high-level block diagram of such a computer is illustrated in Figure 7. Computer 702 includes a processor 704 that controls the overall operation of computer 702 by executing computer program instructions that define such operations. The computer program instructions may be stored in storage device 712, or other computer-readable medium (e.g., magnetic disk, CD ROM, etc.), and loaded into memory 710 when execution of the computer program instructions is desired. Consequently, the operations of Figures 2 and 3, and the method steps of Figures 4, 5, and 6, may be defined by computer program instructions stored in memory 710 and / or storage device 712, and the processor 704 may execute the computer program instructions. 2 and 3 and the method steps of FIGS. 4, 5, and 6. Thus, by executing the computer program instructions, processor 704 performs the algorithm defined by the operations of FIGS. 2 and 3 and the method steps of FIGS. 4, 5, and 6. Computer 702 also includes one or more network interfaces 406 for communicating with other devices over a network. Computer 702 also includes input / output devices 708 (e.g., a display, keyboard, mouse, speakers, buttons, etc.) that allow a user to interact with computer 702. Those skilled in the art will appreciate that actual computer implementations may include other components as well, and that FIG. 7 is a high-level depiction of some such computers for illustrative purposes.

[0120] The foregoing detailed description should be understood in all respects to be illustrative and exemplary, but not restrictive, and the scope of the inventive concepts disclosed herein should be determined not from said detailed description, but rather from the claims as interpreted in full accordance with the patent laws. It should be understood that the embodiments shown and described herein are merely illustrative of the principles of the inventive concepts, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the inventive concepts. Various other configuration combinations could be implemented by those skilled in the art without departing from the scope and spirit of the inventive concepts.

Claims

1. 1. A method for rejecting anomalous measurements and extending a navigation solution of a Global Navigation Satellite System (GNSS) receiver, comprising: calculating an estimated full phase (FP) of a tracked navigation satellite (NS) based on coordinate predictions of the GNSS receiver; calculating an IL discriminator signal of the tracked NS; rejecting M number of NS discriminator signals and generating a corresponding flag; calculating a CL discriminator signal based on K number of non-rejected IL discriminator signals; calculating a current estimate of coordinates and a time scale (RTS) of the GNSS receiver; calculating the FP of the tracked NS based on the current estimate of the GNSS receiver coordinates; calculating a corrected IL discriminator signal for M number of the NS; calculating an integer ambiguity (IA) estimate; and recalculating the corrected IL discriminator signal based on the IA estimate. A method comprising: calculating an FP residual estimate; calculating a SF signal based on a current estimate and a prediction of receiver coordinates; and calculating a receiver coordinate prediction.

2. The calculated FP is calculated based on a prediction of the receiver coordinates for the M number of the NS, and The calculated FP for the jth NS based on the Earth's rotation , tropospheric delay and ionospheric delay Correction for receiver time scale drift q ｉ and N-S time scale drift The calculated pseudorange based on is calculated as, and and The method of claim 1 , wherein j is the coordinate of the jth NS at the time of signal emission.

3. The j-th NS IL discriminator signal is the residual And this residual is calculated as the difference between the predicted where the residual is IA Based on the prediction of And it was calculated is calculated as the difference between where, for the measured FP of NS, and and and λ is the wavelength of the NS signal.

4. is a threshold value h ｓｎｒ Less than or equal to The absolute value of φ If the signal of the IL discriminator of the j-th NS is smaller than 2. The method of claim 1, wherein N are rejected and a corresponding flag is formed, but there are N non-rejected signals of the IL discriminator.

5. CL discriminator signal is the N non-rejected IL discriminator signals is calculated by the least squares method (LSM) according to is the direction cosine matrix padded with the identity matrix for the N non-rejected cases and padded with four rows with identity elements arranged on the diagonal, and W ｉ means that the element is is a diagonal weight matrix proportional to , and the diagonal elements are The method of claim 1 , wherein the calculated value is:

6. The receiver's current estimate and RTS coordinates is the equation a current estimate of the receiver's coordinates, RTS, according to and CL discriminator The method of claim 1 , wherein the calculated value is:

7. Receiver Coordinates The calculated FP for the jth NS based on the equation Using the , tropospheric delay and ionospheric delay Correction for receiver time scale drift and N-S time scale drift The calculated pseudoranges include is calculated as, and The method of claim 1 , wherein j is the coordinate of the jth NS at the time of signal emission.

8. IL discriminator correction signal for M NS is the equation Using the residual and their residuals where the residual of the jth NS is calculated as the difference between the prediction of is the equation The measured FP and the calculated FP The method of claim 1 , wherein the difference is calculated as the difference between

9. The IA estimate for the jth NS case is given by the equation and corrected based on an IL discriminator correction signal defined by:

2. The method of claim 1, wherein IA is a correction to IA, and floor{} is a round-up operation to the previous integer.

10. The IL discriminator correction signal for M number of NS is expressed by the equation where: is the correction to IA in the case of NS of M, and The method of claim 1 , wherein is an operation of replacing an original value with a new value.

11. FP residual estimate at the (i+1)th step is calculated based on the residual prediction for the (i-1)th step and the corrected signal of the IL discriminator, as follows: The method of claim 1 , wherein the calculated value is:

12. smoothed estimates 、 and is the equation where t is the value that the theoretical coordinates take (x, y, z, q), is the current coordinate estimate predicted. and the coefficient K in the case of the coordinates SF (i.e., in the case of x, y, z) １ , K. ２ and K. ３ Is K １ = 0.95, K ２ = 1.1 and K ３ =0.8, where the coefficient K of the RTSq of the smoothing filter １ , K. ２ and K. ３ teeth, K ３ 2. The method of claim 1, wherein the calculation is performed as follows: =0 and z=15.

13. prediction 、 and is the smoothed estimate 、 and where the theoretical coordinates t(x, y, z, q) are calculated based on the equation and The method of claim 1 , wherein the calculated value is:

14. A method for generating a reject flag for an abnormal measurement peak D is as follows: In the i-th step, and the test signal and the test signal based on an estimate of an estimate of the test signal is the threshold h φ Compared to If so, a reject flag is formed, otherwise the reject flag is removed; and for the (j+1)th step, a prediction of the test signal for the jth NS is generated; and, provided that: is the duration of the epoch T e and the LFF bandwidth α.

15. Initialization and restart are performed at BC coordinates. and but the current coordinates of the navigation solution and setting the RTS estimate to but the RTSq from the navigation solution ｉ and the step is set equal to the speed estimate But the current estimate of the navigation speed solution is and the step is set equal to and the initial FP residual of the j-th NS is set to the difference between the measured FP and the calculated FP. and calculating the value of the sum ... is the FP measured at the time of BC initialization or restart, teeth, The method of claim 1, wherein the FP is calculated at the same time according to

16. The correction method is executed every 2 seconds, and the correction method is performed by and coordinates , said navigation solution setting the velocity setting σ equal to the current estimate of the velocity solution; and the estimate of the integer correction is The method of claim 1, wherein

17. The method further includes adding a new j-th NS, and adding the new j-th NS includes: and estimating the measured FP and the calculated FP and calculating an initial FP residual of the jth NS based on a difference between

18. 10. An apparatus comprising an antenna configured to receive signals from GNSS satellites and route those signals through an RF section, an ADC, a primary processing block, and a secondary processing block to a buffer compensator, the buffer compensator configured to perform the method of claim 1.

19. 1. A method for rejecting abnormal measurements and extending FP, comprising: calculating an IL discriminator signal of a tracked NS; rejecting M number of IL discriminator signals of the NS and forming a corresponding flag; calculating a CL discriminator from K non-rejected signals of the IL discriminators; calculating a corrected discriminator signal based on the CL discriminator signal; calculating an FP estimate, Doppler frequency, and rate of change of Doppler frequency of the tracked NS; and calculating a FP prediction, Doppler frequency, and rate of change of Doppler frequency of the tracked NS.

20. The step of calculating the IL discriminator signal for the NS being tracked is performed using the equation Using the j-th NS IL discriminator signal The measured FP and the FP estimate FP 20. The method of claim 19, comprising calculating the difference between

21. The step of rejecting the Mth IL discriminator signal of the NS and forming a corresponding flag comprises: Refusing to is the threshold h ｓｎｒ is less than or The absolute value of φ and forming a corresponding flag if the value is less than the rejection value.

20. The method of claim 19, wherein the number N of the IL discriminator signals that are not rejected remains unchanged.

22. CL discriminator signal is calculated by the LSM according to the N non-rejected IL discriminator signals, where 、 、 and H i is the direction cosine matrix with an added identity column, and W i is the case where the element is not rejected by N. is a diagonal weight matrix proportional to , where the diagonal elements are The method of claim 19, wherein the calculated value is calculated using:

23. The IL discriminator correction signal is a CL discriminator signal projected onto a specific line of sight of the NS. and the N-directional vector of the correction signal is calculated based on the vector of 20. The method of claim 19, wherein the

24. Estimated value of M in the NS case 、 and is FP prediction , Doppler frequency , the rate of change in Doppler frequency and the IL discriminator correction signal Using the equation where CL coefficient is calculated using 、 、 and IL coefficient 、 、 is the equation 20. The method of claim 19, wherein k=3 for the CL coefficients and k=27 for the IL coefficients.

25. Estimated value 、 and is the equation where T ｅ is the duration of an epoch, and The method of claim 19 , wherein the FP correction for the j-th NS motion is calculated based on ephemeris information.

26. Adding a new j-th NS involves determining the coordinates (coordinates) of the j-th NS using ephemeris information at the time of signal emission. ) and the NS time scale drift for the current epoch. Calculating The calculated coordinates of the NS and the coordinates of the receiver (x ０ , y ０ , z ０ Calculating a priori pseudoranges using the estimated values ​​of The FP that can be calculated is the rotation of the Earth. , tropospheric delay and ionospheric delay , RTS drift q i , and N-S time scale drift Based on the equation and calculating the IL discriminator signal for the jth NS using is the equation The method of claim 19, wherein the calculated value is calculated using:

27. 20. An apparatus comprising: an antenna configured to receive signals from GNSS satellites and route those signals through an RF section, an ADC, a primary processing block, and a secondary processing block to a buffer compensator, the buffer compensator configured to perform the method of claim 19.

28. A method for generating IL discriminator signals in a multi-frequency receiver for N S radiated signals in K frequency bands, comprising: and determining the obtained value , the threshold h ｓｎｒ the SNR of the jth NS in frequency band f is greater than the threshold h φ Less than and the absolute value of the signal If one of the criteria is not met, the corresponding signal is rejected and a corresponding flag is generated; , and use L jth NS non-rejected signals to obtain a composite IL discriminator signal and forming a

29. 30. An apparatus comprising: an antenna configured to receive signals from GNSS satellites and route those signals through an RF section, an ADC, a primary processing block, and a secondary processing block to a buffer compensator, the buffer compensator configured to perform the method of claim 28.

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