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Showing papers on "GPS/INS published in 1985"


Patent
15 May 1985
TL;DR: In this paper, a navigation method for the navigation of a vehicle employing direction and longitudinal movement sensors is presented, where signals from the sensors are fed to a position computer which determines the vehicle position relative to a coordinate grid system.
Abstract: A navigation method for the navigation of a vehicle employing direction and longitudinal movement sensors. Signals from the sensors are fed to a position computer which determines the vehicle position relative to a coordinate grid system. When the vehicle reaches a position of known coordinates the position values which are determined from the sensor signals are corrected with reference to the known coordinates, and a Kalman filter is provided which effects an error estimate and subsequently a correction value determination from the error estimate which results in a significant increase in accuracy of the displayed navigation data. The particular advantage of the method is the use of uncomplicated sensors which are able, in connection with the Kalman filter, to obtain highly accurate vehicle position data.

31 citations


Proceedings ArticleDOI
01 Dec 1985
TL;DR: In this article, a doppler processing technique for smoothing the GPS code-phase measurements is presented, which can enhance the resolution of C/A pseudo-range measurements to better than 1 centimeter.
Abstract: A doppler processing technique for smoothing the GPS code-phase measurements is presented. It is shown that this technique can enhance the resolution of C/A pseudo-range measurements to better than 1 centimeter. Data is presented to show that it is possible to obtain position fixes with an runs scatter of a few centimeters from the C/A code. Although the presented technique is applicable to both static and dynamic situations, it is particularly attractive in dynamic applications, where position averaging cannot be performed. This is shown to be a key factor in obtaining sub-meter differential accuracy in low dynamic applications. The interchannel biases in multichannel receivers are also discussed. It is shown how the advantages of multichannel design can be retained without suffering from this effect. The above techniques are implemented in the TRIMBLE 4000A LOCATORs and results are presented in this paper.

25 citations


Journal ArticleDOI
R. Bowen, P. L. Swanson1, F. B. Winn1, N. W. Rhodus1, W. A. Feess1 
TL;DR: Using real and simulated GPS pseudo range radiometric tracking data, The Aerospace Corporation has completed a detailed error analysis which shows that the satellite clock noise contributes more than 90 percent of the total satellite-to-user pseudo range error.
Abstract: In early 1985, an improved ground Operational Control System (OCS) will maintain the navigation service. Primary among the OCS improvements over past GPS navigation systems is a global network of ground antennas (to upload satellite navigation data) and tracking/monitor stations. In addition, a refined Kalman filter will continuously estimate the Global Positioning System (GPS) satellite ephemerides and clock phases and frequencies. Although the user-GPS interface remains unaltered, the accuracy of the GPS navigation service is expected to improve by a factor of three. Using real and simulated GPS pseudo range radiometric tracking data, The Aerospace Corporation has completed a detailed error analysis which shows that the satellite clock noise contributes more than 90 percent of the total satellite-to-user pseudo range error. If the number of OCS uploads is increased to three per day (as planned), then the accuracy of the navigation service is also expected to improve by nearly a factor of three because the clock-noise contribution to the range error increases linearly with time. Also, this analysis shows the consequence of satellite ephermeris uncertainties in the GPS navigation application.

11 citations


Journal ArticleDOI
TL;DR: A new integration scheme is proposed which performs more effective information exchange so that it is more tolerant to rf interferences and unmodeled INS errors (such as errors caused by IMU failures) than the conventional scheme.

3 citations


Proceedings ArticleDOI
15 Dec 1985
TL;DR: A generalized Covariance Error Analysis Simulator (CEASIM) has been developed for GPS/INS integrated navigation systems and can be used to study various Kalman filter and sensor configurations as part of proposal or preliminary design efforts.
Abstract: A generalized Covariance Error Analysis Simulator (CEASIM) has been developed for GPS/INS integrated navigation systems. Equations for the propagation in time of the attitude, position, velocity and sensor errors are implemented with a 64-state system model. Alignment equations for a typical fourth-order INS alignment/calibration loop are incorporated for covariance initialization. CEASIM can be used to study various Kalman filter and sensor configurations as part of proposal or preliminary design efforts. The simulator is capable of analyzing GPS/INS system performance over a variety of mission profiles, including aircraft, ships and land vehicles.

1 citations


Journal ArticleDOI
TL;DR: In this paper, the authors discussed the accuracy of using the Global Positioning System (GPS) satellites for surface navigation and provided theoretical analysis to determine what accuracy in horizontal position may be achieved when range data from various sets of four satellites from the current five-satellite GPS constellation are used to solve for the position state vector.
Abstract: This report discusses the accuracy to be expected in using the Global Positioning System (GPS) satellites for surface navigation. Several theoretical analyses are given to determine what accuracy in horizontal position may be achieved when range data from various sets of four satellites from the current five‐satellite GPS constellation are used to solve for the position state vector. Results indicate a horizontal position accuracy of 10m to 20m may be expected. In addition, the benefits of using a priori vertical position information are discussed, as well as sensitivity to errors in such a priori estimates. The theoretical basis of each analysis is summarized, and the results of each analysis are expressed in terms of the net horizontal position uncertainty resulting from the technique implemented. Finally, the results of using actual recorded GPS data to navigate a receiver with known coordinates are given to provide verification of the theoretical results.

1 citations