IEEE/ION Position, Location and Navigation Symposium 

About: IEEE/ION Position, Location and Navigation Symposium is an academic conference. The conference publishes majorly in the area(s): Global Positioning System & Inertial navigation system. Over the lifetime, 1858 publications have been published by the conference receiving 25479 citations.

A new method for fast carrier phase ambiguity estimation

Abstract: The Global Positioning System (GPS) double-difference carrier phase data are biased by an integer number of cycles. A new and successful method has been developed and demonstrated that enables very fast integer ambiguity estimation. The method makes use of an ambiguity reparametrization that allows one to reformulate the original ambiguity estimation problem into a new problem that becomes much easier to solve. The theoretical concepts of the method are presented, and some representative numerical results are given and discussed. In particular, it is demonstrated that a very significant reduction in both the correlation between the ambiguities and in the elongation of the corresponding confidence ellipsoid can be reached. Typically a reduction by a factor of between 10/sup 2/ and 10/sup 3/ of the square-root of the condition number of the confidence ellipsoid can be obtained. Also the gain in time, which is needed to follow through the various computational steps, is demonstrated. >

Applications of magnetic sensors for low cost compass systems

Abstract: A method for heading determination is described that will include the effects of pitch and roll as well as the magnetic properties of the vehicle. Using solid-state magnetic sensors and a tilt sensor, a low cost compass system can be realized. Commercial airlines today use attitude and heading reference systems that cost tens of thousands of dollars. For general aviation, or small private aircraft, this is too costly for most pilot's budget. The compass system described here provides heading, pitch and roll outputs accurate to one degree, or better. The shortfall of this low-cost approach is that the compass outputs are affected by acceleration and turns. A solution to this problem is also presented.

The multipath estimating delay lock loop: approaching theoretical accuracy limits

Abstract: This paper demonstrates that it is possible to largely reduce GPS code and carrier multipath errors by using a specific receiver structure which simultaneously estimates the parameters of line-of-sight plus multipath signals. Test results in various environments show an error reduction up to a factor of ten, as compared to a receiver with a small early-late spacing. >

MBOC: The New Optimized Spreading Modulation Recommended for GALILEO L1 OS and GPS L1C

Abstract: This paper describes the Multiplexed Binary Offset Carrier (MBOC) spreading modulation that has been recommended by the GPS-GALILEO Working Group on Interoperability and Compatibility. The MBOC(6,1,1/11) power spectral density is a mixture of BOC(1,1) spectrum and BOC(6,1) spectrum, that would be used by GALILEO for its Open Service (OS) signal at L1 frequency, and also by GPS for its modernized L1 Civil (L1C) signal. A number of different time waveforms can produce the MBOC(6,1,1/11) spectrum, allowing flexibility in implementation, although interoperable waveforms remains an objective for GALILEO and GPS. The time-multiplexed BOC (TMBOC) implementation interlaces BOC(6,1) and BOC(1,1) spreading symbols in a regular pattern, whereas composite BOC (CBOC) uses multilevel spreading symbols formed from the weighted sum of BOC(1,1) and BOC(6,1) spreading symbols, interplexed to form a constant modulus composite signal. This paper provides information on the history, motivation, and construction of MBOC signals. It then shows various performance characteristics, and summarizes their status in GALILEO and GPS signal design.

A gyro-free quaternion-based attitude determination system suitable for implementation using low cost sensors

Abstract: Attitude determination systems that use inexpensive sensors and are based on computationally efficient and robust algorithms are indispensable for real-time vehicle navigation, guidance and control applications. This paper describes an attitude determination system that is based on two vector measurements of non-zero, non-colinear vectors. The algorithm is based on a quaternion formulation of Wahba's (1966) problem, whereby the error quaternion (q/sub e/) becomes the observed state and can be cast into a standard linear measurement equation. Using the Earth's magnetic field and gravity as the two measured quantities, a low-cost attitude determination system is proposed. An iterated least-squares solution to the attitude determination problem is tested on simulated static cases, and shown to be globally convergent. A time-varying Kalman filter implementation of the same formulation is tested on simulated data and experimental data from a maneuvering aircraft. The time-varying Kalman filter implementation of this algorithm is exercised on simulated and real data collected from an inexpensive triad of accelerometers and magnetometers. The accelerometers in conjunction with the derivative of GPS velocity provided a measure of the gravitation field vector and the magnetometers measured the Earth's magnetic field vector. Tracking errors on experimental data are shown to be less than 1 degree mean and standard deviation of approximately 11 degrees in yaw, and 3 degrees in pitch and roll. Best case performance of the system during maneuvering is shown to improve standard deviations to approximately 3 degrees in yaw, and 1.5 degrees in pitch and roll.