CN109581453A - GNSS sectionally smooth filtering method based on cycle-slip detection and repair - Google Patents
GNSS sectionally smooth filtering method based on cycle-slip detection and repair Download PDFInfo
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- CN109581453A CN109581453A CN201811617351.1A CN201811617351A CN109581453A CN 109581453 A CN109581453 A CN 109581453A CN 201811617351 A CN201811617351 A CN 201811617351A CN 109581453 A CN109581453 A CN 109581453A
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- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000001914 filtration Methods 0.000 title claims abstract description 20
- 238000001514 detection method Methods 0.000 title claims abstract description 12
- 238000009499 grossing Methods 0.000 claims description 20
- 238000012546 transfer Methods 0.000 claims description 9
- 230000011218 segmentation Effects 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 claims description 4
- 238000013461 design Methods 0.000 claims description 4
- 239000011159 matrix material Substances 0.000 claims description 4
- 238000012937 correction Methods 0.000 claims description 2
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/42—Determining position
- G01S19/43—Determining position using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
- G01S19/44—Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/25—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS
- G01S19/258—Acquisition or tracking or demodulation of signals transmitted by the system involving aiding data received from a cooperating element, e.g. assisted GPS relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
- G01S19/37—Hardware or software details of the signal processing chain
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Abstract
The present invention provides a kind of GNSS sectionally smooth filtering method based on cycle-slip detection and repair, it include: after carrying out cycle-slip detection and repair to original observed data, if effectively view number of satellite is more than certain amount altogether, it is calculated in section with Kalman filter forward filtering, and determine fuzziness, the most moment t of total view number of satellite for selecting fuzziness to fixm, as reversed smooth starting point；By what reversed smooth starting point had been fixed total previous epoch t is inversely transferred to depending on satellite fuzzinessm‑1, for tm‑1Epoch-making moment updates positioning result in conjunction with satellite carrier phase raw observation and the total view satellite fuzziness transmitted；Using the positioning result and carrier phase observation data of update, reverse inverse and fixed tm‑1Other non-view satellite fuzzinesses altogether of moment；If other non-satellite fuzzinesses of view altogether are rounded precision and standard deviation in setting threshold value, fuzziness is fixed successfully；Conversely, the fixed failure of fuzziness.
Description
Technical Field
The invention relates to a high-precision GNSS navigation positioning post-processing technology, in particular to a GNSS segmentation smoothing filtering method based on cycle slip detection and repair.
Background
Global Navigation Satellite System (GNSS) has all-weather, all-time, Global coverage features, and is widely used in many fields, such as sea, land, air, sky, and earth. GNSS can be classified into pseudo-range positioning and carrier-phase positioning according to the type of observation value. The pseudo-range positioning algorithm is simple, but due to the fact that observation noise is large and the influence of multipath effect is serious, only meter-level positioning accuracy can be provided usually. To achieve high-precision positioning of dynamic single epoch, a carrier phase positioning method is often selected.
However, in carrier phase positioning, carrier phase observations often occur over an entire number of weeks of hopping, i.e., cycle slip, due to high receiver dynamics, low satellite elevation, signal shadowing, etc. The occurrence of cycle slip causes the ambiguity to reinitialize. If the cycle slip is not effectively repaired, the positioning accuracy will be reduced, and even the positioning is re-converged in serious cases. In addition, when dynamic single-epoch positioning is performed in complex environments such as mountainous areas and urban canyons, the phenomena of small number of observation satellites, poor satellite observation data quality and the like often occur. This will lead to the problems of frequent cycle slip, difficulty in fixing the ambiguity, and a large number of floating solutions in the positioning result. Therefore, some scholars propose to use a bi-directional or tri-directional filtering method to smooth the error generated when the cycle slip occurs. Although the methods can improve the positioning precision to a certain extent, the dynamic state model of the satellite positioning system is difficult to accurately describe, and the filtered positioning result is still a floating point solution.
Disclosure of Invention
The invention aims to provide a GNSS segmented smoothing filtering method based on cycle slip detection and repair, which comprises the following steps:
step 1, after cycle slip detection and restoration are carried out on original observation data, a common-view satellite with no cycle slip occurring between adjacent epochs or the cycle slip restored is regarded as an effective common-view satellite, if the number of the effective common-view satellites is less than a certain number, cycle slip restoration is considered to fail, a new segment occurs, and the ambiguity is recalculated at the moment.
Step 2, forward filtering calculation is carried out by using a Kalman filter in the section, the ambiguity is determined, and the moment t with the maximum number of the common-view satellites with fixed ambiguity is selectedmAs a reverse smoothing starting point.
Step 3, fixing the ambiguity of the common-view satellite at the reverse smooth starting pointBackward transfer to previous epoch tm-1For tm-1Updating a positioning result at the epoch time by combining the original observation value of the satellite carrier phase and the transferred common-view satellite ambiguity;
and 4, reversely calculating and fixing t by using the updated positioning result and the carrier phase observed valuem-1Time of day other non-common view satellite ambiguities
Step 5, if the ambiguity of other non-common-view satellitesThe rounding precision and the standard deviation are both within the set threshold value, then the ambiguity isFixing is successful; conversely, degree of ambiguityThe fixation fails.
The method is based on the number of effective common view satellites, segmentation is carried out through cycle slip detection and repair processing, and the ambiguity in the segment is recalculated; in the section, the continuity of the ambiguity between adjacent epochs is fully utilized, the ambiguity of the fixed epoch is reversely transmitted to the preamble epoch, and the positioning result is updated. Compared with the existing methods such as bidirectional filtering and three-way filtering, the method obviously improves the fixation rate of ambiguity during the period that GNSS signals start to be captured or cycle slip occurs, improves the navigation positioning precision, and is particularly suitable for the post-processing of dynamic single-epoch positioning data.
The invention is further described below with reference to the accompanying drawings.
Drawings
FIG. 1 is a flow chart of a GNSS piecewise smoothing filtering method.
Fig. 2 is a graph of satellite ambiguity transfer between adjacent epochs.
FIG. 3 is a diagram illustrating a timing process after a cycle slip of GNSS signals.
Detailed Description
As shown in fig. 1, the main principle of the GNSS segmentation smoothing filtering method based on cycle slip detection and repair is as follows: and on the basis of the effective common-view satellite, the cycle slip repair failure is regarded as a new segment, and the in-segment ambiguity is recalculated. After the ambiguity in the section is fixed, selecting a reverse smoothing starting point, reversely transmitting the fixed ambiguity of the common-view satellite to a previous epoch, and updating a previous epoch positioning result; aiming at the previous epoch, combining the updated positioning result and the original observed value of the carrier phase, reversely calculating and fixing the ambiguity of the non-common-view satellite; and performing reverse smoothing in sequence until the cycle slip repairing fails.
The invention mainly comprises the following steps:
step 1. segmentation
And (3) performing cycle slip detection and repair on the original observation data by using a traditional TurboEdit method, and recording satellites which have cycle slips but are not repaired.
The same observation satellite appearing between the adjacent epochs is regarded as a common-view satellite, and the common-view satellite with no cycle slip or repaired cycle slip between the adjacent epochs is regarded as an effective common-view satellite. If the total number of the effective co-view satellites in the single system is less than 5, the total number of the effective co-view satellites in the double system is less than 6, the total number of the effective co-view satellites in the three systems is less than 7, or the number of the effective satellites in the single system is less than 2 in the multiple systems, a new segment is considered to occur, and the ambiguity is recalculated at this time.
Step 2. in-segment forward filtering
In the section, the forward filtering calculation of a Kalman filter is used for fixing double-difference (inter-station difference and inter-satellite difference) ambiguity. When the ambiguity is fixed, selecting the moment t with the maximum number of the common-view satellites with fixed ambiguitymThis time is recorded as the starting point of the inverse smoothing. If the ambiguity cannot be effectively fixed in the forward filtering process in the segment, the floating point solution is taken as a final positioning result, and the backward smoothing in the segment is not carried out any more.
Step 3. intra-segment reverse smoothing
At the backward smoothing start point recorded by the forward filtering within a segment, i.e. tmAt that time, the ambiguity is transferred in reverse.
Will tmCommon view satellite ambiguity with fixed timeBackward transfer to previous epoch tm-1. The inversely transferred ambiguities are single-difference (inter-station difference) ambiguities, and the single-difference ambiguities are converted from double-difference ambiguities. The single-difference ambiguities are passed in reverse to avoid the effects of reference satellite variations in the reverse smoothing. The reverse transfer of the ambiguity parameters fully utilizes the correlation of the ambiguity between adjacent epochs and realizes effective transfer between the common-view satellites.
For tm-1And updating a positioning result by combining the original observation value of the satellite carrier phase and the transferred common-view satellite ambiguity at the epoch moment, namely:
wherein, the lambda is the wavelength of the carrier wave,is tm-1The time of day is co-viewing the carrier phase raw observations of the satellites,is tm-1Design matrix of the time-of-day common view satellite, dx being tm-1The time position correction number. The calculated fixing solution is used as the final positioning result.
Utilizing the updated positioning result and the observed value of the carrier phase to reversely calculate and fix tm-1Time of day other non-common view satellite ambiguities
wherein ,is tm-1The design matrix of the non-public view satellite at the time,is tm-1And (3) a carrier phase original observed value of a non-co-view satellite at the moment.
If other non-co-view satellite ambiguitiesWhen the rounding precision is within 0.2 week and the standard deviation is within 0.1 week, the ambiguity is considered to be fixed and can be transmitted to the next epoch. In this way, the smoothing is reversed in sequence untilAnd (5) the cycle slip repair failure moment.
In addition, the present invention relates to efficient transfer of satellite ambiguities between adjacent epochs, as shown in FIG. 2. The effective transfer of ambiguity between adjacent epochs is detailed in the figure. For the common-view satellite, directly assigning the ambiguity of the common-view satellite which is fixed at the current moment to the previous epoch moment; and for the non-common-view satellite, performing reverse back calculation by using the ambiguity of the fixed common-view satellite at the moment to obtain an ambiguity fixed value of the non-common-view satellite.
The actual time sequence processing after the cycle slip of the GNSS signal according to the present invention is shown in fig. 3. Wherein, the effective carrier phase observed quantity is represented by green mark points. Once the GNSS signals are blocked by a certain obstacle, the satellite signals are often interrupted, and the GNSS receiver is unlocked. When the receiver moves, the GNSS signals are reacquired and a cycle slip often occurs, generating a new segment. In the initial stage of the new segment generation, the positioning accuracy of the receiver is low. When a new segment occurs for a period of time, the ambiguity gradually converges, and the positioning accuracy of the receiver is also gradually improved. At this time, a proper reverse smoothing starting point is selected, the ambiguity of the convergence time is reversely transmitted to the preamble epoch, and finally the positioning accuracy is improved.
Claims (9)
1. A GNSS segmentation smoothing filtering method based on cycle slip detection and restoration is characterized by comprising the following steps:
step 1, after cycle slip detection and restoration are carried out on original observation data, a common-view satellite with no cycle slip occurring between adjacent epochs or the cycle slip restored is regarded as an effective common-view satellite, if the number of the effective common-view satellites is less than a certain number, cycle slip restoration is considered to fail, a new segment occurs, and the ambiguity is recalculated at the moment; otherwise, turning to the step 2.
Step 2, forward filtering calculation is carried out by applying a Kalman filter in the section, and a module is determinedAmbiguity, selecting the time t at which the maximum number of common-view satellites with fixed ambiguity ismAs a reverse smoothing starting point.
Step 3, fixing the ambiguity of the common-view satellite at the reverse smooth starting pointBackward transfer to previous epoch tm-1For tm-1Updating a positioning result at the epoch time by combining the original observation value of the satellite carrier phase and the transferred common-view satellite ambiguity;
and 4, reversely calculating and fixing t by using the updated positioning result and the carrier phase observed valuem-1Time of day other non-common view satellite ambiguities
Step 5, if the ambiguity of other non-common-view satellitesThe rounding precision and the standard deviation are both within the set threshold value, then the ambiguity isFixing is successful; conversely, degree of ambiguityThe fixation fails.
2. The method according to claim 1, wherein in step 3, the updated positioning result is obtained according to equation (1)
Wherein, the lambda is the wavelength of the carrier wave,is tm-1The time of day is co-viewing the carrier phase raw observations of the satellites,is tm-1Design matrix of the time-of-day common view satellite, dx being tm-1The time position correction number.
3. The method of claim 1, wherein in step 4, t is obtained according to equation (2)m-1Time of day other non-common view satellite ambiguities
wherein ,is tm-1The design matrix of the non-public view satellite at the time,is tm-1And (3) a carrier phase original observed value of a non-co-view satellite at the moment.
4. The method of claim 1, wherein the co-view satellite in step 1 is the same observation satellite that occurs between adjacent epochs.
5. The method according to claim 1, wherein the segmentation in step 1 is performed according to the number of effective co-view satellites, and specifically, when the total number of effective co-view satellites in a single system is less than 5, the total number of effective co-view satellites in a dual system is less than 6, the total number of effective co-view satellites in three systems is less than 7, or the number of effective satellites in a single system under multiple systems is less than 2, the cycle slip repair is considered to fail, and a new segment occurs.
6. The method of claim 1 wherein in step 2, intra-segment forward filtering is performed, and if the ambiguity is not fixed effectively, the floating solution is used as the final result without intra-segment backward smoothing.
7. The method of claim 1, wherein in step 2, mid-segment forward filtering, the fixed ambiguity is a double-difference ambiguity; and 3, performing reverse smoothing in the middle section, wherein the ambiguity of reverse transmission is single-difference ambiguity. The single-difference ambiguity is converted from double-difference ambiguity, and the single-difference ambiguity is transferred in a reverse direction to avoid the influence caused by the change of a reference satellite in the reverse smoothing.
8. The method of claim 1 wherein the ambiguity parameters are transferred in reverse in step 3 by using the correlation of ambiguities between adjacent epochs to achieve efficient transfer between co-view satellites.
9. Method according to claim 1, characterized in that t is fixed in step 3m-1Time of day other non-common view satellite ambiguitiesFor floating point solution, the rounding precision threshold is set to be 0.2 week, and the standard deviation threshold is set to be 0.1 week.
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| CN111551971A (en) * | 2020-05-14 | 2020-08-18 | 中国北方工业有限公司 | Method for supporting pilot frequency GNSS signal pseudo-range differential positioning |
| CN115267847A (en) * | 2022-06-27 | 2022-11-01 | 湘潭大学 | Single-frequency cycle slip detection and restoration method, system, equipment and medium |
| US20230296786A1 (en) * | 2019-12-11 | 2023-09-21 | Swift Navigation, Inc. | System and method for validating gnss ambiguities |
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