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WO2002004978A1 - Systeme de releve de positionnement - Google Patents

Systeme de releve de positionnement Download PDF

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Publication number
WO2002004978A1
WO2002004978A1 PCT/DK2001/000453 DK0100453W WO0204978A1 WO 2002004978 A1 WO2002004978 A1 WO 2002004978A1 DK 0100453 W DK0100453 W DK 0100453W WO 0204978 A1 WO0204978 A1 WO 0204978A1
Authority
WO
WIPO (PCT)
Prior art keywords
signals
position vectors
antenna
operable
computed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DK2001/000453
Other languages
English (en)
Inventor
Kai Borre
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GPS SURVEY APS
Original Assignee
GPS SURVEY APS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by GPS SURVEY APS filed Critical GPS SURVEY APS
Priority to AU2001268952A priority Critical patent/AU2001268952A1/en
Publication of WO2002004978A1 publication Critical patent/WO2002004978A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
    • G01S19/04—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing carrier phase data
    • 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
    • G01S19/22—Multipath-related issues

Definitions

  • the present invention relates to a method for reducing the effect of multipath in survey systems using signals received from positioning satellites as described in the preamble of claim 1.
  • the invention relates further to an apparatus for obtaining position vectors between a reference location and a geographic relative point of interest.
  • Multipath errors can be filtered from the received signals if the difference in distance between the direct and the reflected signals are larger than 10 m. Furthermore, for signals that have been reflected an odd number of times, the polarisation of the signal is different from the original signal and can also be filtered out. However, for errors that are introduced by multipath where the distance difference between the direct and the reflected signals is less than 10 m, no model for reduction is known. However, any reduction of this error would result in a higher precision of the position.
  • the highest precision is desirable when detecting movements of for example buildings, bridges, or off-shore platforms. Using a high precision may indicate at an early stage, whether precautions have to be taken to avoid catastrophes.
  • the literature does not describe that omnipresent multipath errors may be corrected in this special manner.
  • the method is based on the fact that the configuration of position satellites repeats with a certain periodicity, which in the following is called D hours. For GPS this is 23 hours 56 minutes, and for GLONASS 22 hours 32 minutes. Therefore, signals from positional satellites received D hours apart should in principle be identical. After making the double differenced observations, the multipath correction is the final step for obtaining more precise positions.
  • ionospheric delay is put equal to zero. If the ionosphere cannot be ignored we apply ionospheric weighting which is somewhere in between ionosphere fixed and ionosphere float solutions. This results in a shorter observation time span required to resolve the carrier ambiguities.
  • the tropospheric delay is computed according to the Goad-Goodman model. This model may be calibrated by simultaneously estimating the tropospheric zenith delay.
  • an an- tenna is located at the object and a reference antenna is located at the reference point.
  • the observation data from these two locations are transmitted to a computer where the signals are double differenced.
  • the basic system architecture consists of a network of GPS sensor nodes and a central data processing station (personal computer).
  • Raw GPS data in the form of pseu- dorange and phase observations are collected by the sensor nodes and transferred to the central processing station.
  • each epoch we thus compute the position of the antenna from the observations, preferably more than four.
  • the computation is made as a least-squares estimation; this yields a residual for every observation.
  • This procedure can be used at the reference point as well as at all other object points.
  • the residuals build up a table of multipath corrections at every antenna for every satellite.
  • These residuals are to be applied to any observation taken D hours later. This means that all residuals are to be stored for at least D hours. If a large residual occurs, we ask: is the residual too large to be accepted as being random or shall it simply be deleted ? The software acts appropriately according to the answer.
  • FIG. 1 is a system diagram of one embodiment of the invention
  • FIG. 2 is a flow diagram illustrating the method of the invention.
  • FIG. 1 is a system diagram of one embodiment of the invention.
  • a first - reference - antenna 1 is located at a reference point 3, whereas a second - object - antenna 2 is located at a different object location 4.
  • the number of object antennas 2 is in principle not limited to one antenna, but several different object locations 4 with antennas may be surveyed relative to the reference point 3.
  • the first 1 and the second 2 antenna receive signals from a plurality of positional satellites 5, preferably more than four. In order to obtain the highest precision, it is necessary that antennas 1, 2 have the same specification and that they are mounted with identical orientation and on very stable foundations that are in stable connection with the structure to be monitored.
  • the signals from the antenna 1, 2 are transmitted by first transmission links 11, 11 ' to GPS receivers 7, 8.
  • the observations from receivers 7 and 8 are then transmitted by further wired links or radio transmission links 10, 10' to a data receiver 9 connected to a computer station 6.
  • the coordinate differences between the object location 4 and reference point 3 are computed.
  • the transmission links are wired links, it is preferable to use identical cables of equal length for not introducing any uncontrolled time delay which may decrease the accuracy of the total system.
  • Biases between the receiver channels and between the LI and L2 observations are small of the order of 0.2-0.3 mm. It is possible to model and estimate any receiver- dependent offsets in the computer software if so desired.
  • the distance between the antennas limits the accuracy that can be obtained, such that a larger distance between antennas results in a less accurate determination of the baseline vector. Therefore, it is preferred that the distance between antennas 1, 2 is less than 1 km; additionally the second order correction term for the ionospheric delay restricts the height difference to be less than 20 meter. Obeying these restrictions it is possible to achieve a relative position accuracy less than one mm if the method according to the invention is employed.
  • the observations are double differenced to eliminate errors like satellite clock errors, eventual delays in cables, ionospheric delays, tropospheric delays.
  • the observations are corrected for the remaining multipath delay by the method according to the invention, wherein the computed relative positions are computed from observations corrected by residuals estimated D hours earlier. This final step reduces the position precision from cm level to mm level.
  • the residuals corre- sponding to each satellite are stored in memory at the computer station 6 for use in the forthcoming D hours.
  • the number of satellites being tracked are at least four, but it is preferable to use signals from more satellites, for example six or eight in order to achieve an accurate and reliable solution.
  • the computer station 6 may receive observation data with a rate of 1
  • FIG. 2 a flow diagram shows the method according to the invention.
  • the first D hours period is used as an initialisation period where position data are obtained (1- obtaining position data in initialisation period) and where the computed three dimensional position vectors and corresponding residuals (2-calculating position vectors and residuals) during that period are stored (3 -storing position vectors and residuals in a memory). These observations are taken at predefined intervals, for example every second.
  • a new set of data is obtained (4-obtain a new set of data after D hours) and the computed position vectors (5-compute position vectors and residuals) are compared to the vectors that were obtained D hours earlier (6- compare with vectors D-hours earlier, are they the same? Yes/No). If the vectors are identical within a predetermined threshold value, an OK indication is given (7-indicate OK), the computed vectors and residuals are stored (8-store vectors and residuals) and the procedure 4 is started again.
  • an indication is given (9-indicate difference), for example as a message on a computer display, and different routines are run to identify the cause of the difference.
  • a given threshold value say 3 mm
  • the components in all three dimensions have to satisfy another given threshold value, for example 1 mm. If the threshold is violated, it leads to an alarm written on the computer screen. If not violated an OK statement is given. The latter should be the normal situation.

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

L'invention concerne un procédé de réduction de l'influence de retard de trajets multiples sur des signaux, dans des systèmes de relevé de positionnement mettant en oeuvre des signaux reçus à partir de satellites GPS; ce procédé est caractérisé en ce que la constellation -basée position- des satellites GPS est périodique -sa périodicité étant de D heures-, et il consiste à comparer des vecteurs de position calculés avec des vecteurs de position correspondants, tels que les D heures calculées plus tôt, de manière à obtenir une précision relative inférieure à un millimètre, pour des objets distants de moins d'un kilomètre, avec une différence de hauteur inférieure à 20 mètres.
PCT/DK2001/000453 2000-07-06 2001-06-29 Systeme de releve de positionnement Ceased WO2002004978A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001268952A AU2001268952A1 (en) 2000-07-06 2001-06-29 Positioning survey system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA200001053 2000-07-06
DK200001053A DK200001053A (da) 2000-07-06 2000-07-06 Positionsovervågningssystem

Publications (1)

Publication Number Publication Date
WO2002004978A1 true WO2002004978A1 (fr) 2002-01-17

Family

ID=8159602

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK2001/000453 Ceased WO2002004978A1 (fr) 2000-07-06 2001-06-29 Systeme de releve de positionnement

Country Status (3)

Country Link
AU (1) AU2001268952A1 (fr)
DK (1) DK200001053A (fr)
WO (1) WO2002004978A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004088349A1 (fr) * 2003-03-31 2004-10-14 Locata Corporation Systeme et procede pour attenuer les trajets multiples au moyen de signaux de positionnement en grappes

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5323322A (en) * 1992-03-05 1994-06-21 Trimble Navigation Limited Networked differential GPS system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5323322A (en) * 1992-03-05 1994-06-21 Trimble Navigation Limited Networked differential GPS system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
CANNON M.: "Performance analysis of a narrow correlator spacing receiver for precise static GPS positioning", POSITION LOCATION AND NAVIGATION SYMPOSIUM, 1994, IEEE, 11 April 1994 (1994-04-11) - 15 April 1994 (1994-04-15), pages 355 - 360, XP000489364 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004088349A1 (fr) * 2003-03-31 2004-10-14 Locata Corporation Systeme et procede pour attenuer les trajets multiples au moyen de signaux de positionnement en grappes
AU2004225455B2 (en) * 2003-03-31 2009-06-04 Locata Corporation Pty Ltd A system and method for multipath mitigation using clustered positioning signals
KR101034742B1 (ko) * 2003-03-31 2011-05-17 로카타 코퍼레이션 클러스터링된 포지셔닝 신호를 이용하는 다중경로 완화를위한 시스템과 방법

Also Published As

Publication number Publication date
DK200001053A (da) 2002-01-07
AU2001268952A1 (en) 2002-01-21

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