A Signal Model for GPS

Braasch, Michael S.

doi:10.1002/j.2161-4296.1990.tb01562.x

Cited by 31 publications

(11 citation statements)

References 5 publications

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“…Multipath is a phenomenon in which signals arrive at a receiver antenna following multiple pathways, usually due to reflection in the atmosphere [7]. These effects may be different for each station, depending on receiver antenna location.…”

Section: Systematic Errors In Gpsmentioning

confidence: 99%

Mitigating Systematic Errors for Single Frequency GPS Receivers Employing a Penalized Least Squares Methodology

Alves

2006

Navigation

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Among the positioning systems that compose GNSS (Global Navigation Satellite System), GPS has the capability of providing low, medium and high precision positioning data. However, GPS observables may be subject to many different types of errors. These systematic errors can degrade the accuracy of the positioning provided by GPS. These errors are mainly related to GPS satellite orbits, multipath, and atmospheric effects. In order to mitigate these errors, a semiparametric model and the penalized least squares technique were employed in this study. This is similar to changing the stochastical model, in which error functions are incorporated and the results are similar to those in which the functional model is changed instead. Using this method, it was shown that ambiguities and the estimation of station coordinates were more reliable and accurate than when employing a conventional least squares methodology.

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Section: Systematic Errors In Gpsmentioning

confidence: 99%

Mitigating Systematic Errors for Single Frequency GPS Receivers Employing a Penalized Least Squares Methodology

Alves

2006

Navigation

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“…The pseudorange is this time interval multiplied by the speed of light in free space. [52] identified the following components in the pseudorange observation.…”

Section: Pseudorange Observation Equation: Relationship To Absolute Pmentioning

confidence: 99%

The Global Positioning System Geodesy Odyssey

et al. 2002

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“…Also, with airdrop the loads may not be fully recoverable, and loss of the authorized receivers would not be desirable. Modeling techniques for GPS range errors resulting from these sources have been developedand validated 6 to model range errors and not errors in a Cartesian reference as desired here. Cartesian (x, y, z) errors would therefore have to be formed from the range errors for implementation in this simulation.…”

Section: Sensor Modelsmentioning

confidence: 99%

Guidance and Control for Flat-Circular Parachutes

Dellicker

Benney

Brown³

2001

Journal of Aircraft

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The Affordable Guided Airdrop System (AGAS) is being evaluated as a low-cost alternative for meeting the military's requirements for precision airdrop. Designed to bridge the gap between relatively expensive high-glide ratio parafoil systems and uncontrolled ballistic parachutes, the AGAS concept offers the bene ts of high-altitude parachute releases as well as the potential for highly accurate point-of-use delivery of material. The design goal of the AGAS development is to provide a guidance, navigation, and control system that can be placed in line with cargo parachute systems, for example the G-12 at-circular parachute, and standard delivery containers (A-22) without modifying these elded systems. The AGAS is required to provide an accuracy of 328 ft (100 m), circular error probable (CEP), with a desired goal of 164 ft (50 m) CEP. The feasibility of this concept was investigated through modeling and simulation. A three-degree-of-freedom (3DOF) point mass ight dynamics model, sensor models of a commercial global positioning system (GPS) receiver and magnetic compass, and a model of the control and actuator system were incorporated into a Monte Carlo simulation tool. A bang-bang controller was implemented with trajectory tracking algorithms using position and heading information. Flight testing, using a radio-controlled scaled prototype, provided parachute dynamic and control response data to support the modeling efforts. The study demonstrated that this concept has the potential to provide control of previously unguided round parachutes to accuracies of approximately 210 ft (64 m) CEP. The program is now continuing into the next phase to include the development of a full-scale prototype system for payloads up to 2200 lb (1000 kg).

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A Signal Model for GPS

Cited by 31 publications

References 5 publications

Mitigating Systematic Errors for Single Frequency GPS Receivers Employing a Penalized Least Squares Methodology

Mitigating Systematic Errors for Single Frequency GPS Receivers Employing a Penalized Least Squares Methodology

The Global Positioning System Geodesy Odyssey

Guidance and Control for Flat-Circular Parachutes

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