Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Patent
1997-08-28
1999-06-08
Issing, Gregory C.
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
G01S 502
Patent
active
059107898
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a method for integrity monitoring in position determination by means of the Global Positioning System (GPS), especially by means of differential GPS (DGPS) or multi-station DGPS, wherein a monitor station is employed with a first GPS receiver provided at a location with a known geographical position.
It is normally desirable to have a high degree of certainty that a navigation aid really provides a performance which lies within the expected range of accuracy. A standard method is to employ a surplus of measurements in order to verify this, e.g. by means of statistic test methods. When using GPS this excess is dependent on the number of satellites which are visible to the user at any time, which at times means that the control of surplus measurements is reduced. The typical navigation user will have to compensate for this by employing greater safety margins which can lead to disadvantages and increased costs.
In the context of entrepreneur activity where fixed measured points do not exist within reasonable proximity such as offshore, for activities such as, e.g., the acquisition of seismic data or pipe laying, it will be of great economic importance to be able to verify the reliability of the positioning system within the same tolerance independent of the number of available satellites.
A method is proposed herein which will make this kind of integrity monitoring possible.
At present GPS is in the process of developing into a universal navigation system for use onshore, at sea and in the air. The system is owned by the US authorities and is placed at the disposal of all users who acquire a GPS receiver. The system is therefore very inexpensive for the user. Moreover the system has a global coverage which is quite unique in comparison with previous systems, while at the same time it offers the possibility of performing extremely accurate position determination.
GPS will therefore be the natural choice of navigation system in the future for most people who require to navigate.
It is highly desirable that the necessary control of the GPS application can be verified without incorporating extra systems since these will usually have a limited range of coverage as well as increasing the costs and thereby losing many of the advantages of using GPS.
A typical demanding application of GPS position determination is in connection with the acquisition of marine seismic data. In this field so-called differential GPS is used in which correction data is broadcast from measuring stations located at known points. By utilizing these corrections the accuracy can be substantially improved and this kind of application is typical for accuracy requirements in the range 0.5-10 meters. In seismic data acquisition it is also normal practice to have buoys deployed in the water and these may also by towed by a vessel. The position of the buoys is also required to be known with a high degree of accuracy, and GPS is also a suitable system for performing such a determination. In this case a relative determination is made between, e.g., the boat and the buoy concerned.
The fact that both a high degree of accuracy is required here and simultaneously a high degree of certainty that the actual performance should agree with the estimated or expected performance makes integrity monitoring extremely demanding. There is a requirement that errors which are not appreciably greater than the noise in the system should be detected and rendered harmless. The economic risk involved in faulty positioning of geological information and constructions is formidable. The proposed method will be an aid to solving this problem.
The use of a navigation system will always be encumbered with errors. The coincidental errors, i.e. random noise, are relatively harmless in this connection. The level of this noise is generally used to describe the accuracy of a system, and in the case of GPS the level of this noise is low. Such errors are easily dealt with by recognized calculation algorithms based on the least squares method or Kalman filtering.
REFERENCES:
patent: 4809005 (1989-02-01), Counselman, III
patent: 5252982 (1993-10-01), Frei
patent: 5436632 (1995-07-01), Sheynblat
patent: 5504492 (1996-04-01), Class et al.
Mark A Sturza, Navigation System Integrity Monitoring Using Redundant Measurements, Navigation: Journal of The Institute of Navigation, vol. 35, No. 4, Winter 1988-1989, pp. 483-501.
Batzer William B.
Garrod David
Geco A.S.
Issing Gregory C.
Smith Keith G. W.
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