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OPTIMIZATION OF REFERENCE WAVEFORM FILTERS IN COHERENT DELAY LOCKED LOOPSGunawardana, Upul, Kosbar, Kurt 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, a new coherent correlation-loop architecture for tracking direct-sequence
spread-spectrum signals is proposed. In the proposed correlation loop
model, the mean-square tracking error is minimized by varying the cross-correlation
function between the received signal and the locally generated signal. The locally
generated signal is produced by passing a replica of the transmitted signal through a
linear time-invariant filter, which is termed the VCC filter. The issue of bandwidth of
a correlation loop is addressed and a bandwidth definition for comparative purposes
is introduced. The filter characteristics to minimize the tracking errors are determined
using numerical optimization algorithms. This work demonstrates that the amplitude
response of the VCC filter is a function of the input signal-to-noise ratio (SNR). In
particular, the optimum filter does not replicate a differentiator at finite signal-to-noise
ratio as is sometimes assumed. The optimal filter characteristics and the
knowledge of the input SNR can be combined to produce a device that has very low
probability of loosing lock.
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NEAR-FAR RESISTANT PSEUDOLITE RANGING USING THE EXTENDED KALMAN FILTERIltis, Ronald A. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Pseudolites have been proposed for augmentation/replacement of the GPS system in radiolocation
applications. However, a terrestrial pseudolite system suffers from the near-far effect due to received
power disparities. Conventional code tracking loops as employed in GPS receivers are unable to
suppress near-far interference. Here, a multiuser code tracking algorithm is presented based on the
extended Kalman filter (EKF.) The EKF jointly tracks the delays and amplitudes of multiple received
pseudolite waveforms. A modified EKF based on an approximate Bayesian estimator (BEKF) is also
developed, which can in principle both acquire and track code delays, as well as detect loss-of-lock.
Representative simulation results for the BEKF are presented for code tracking with 2 and 5 users.
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On the Modified PN Code Tracking Loop with Multiuser Detection and Multipath Interference CancellationLin, Yu-hui 28 August 2004 (has links)
A non-coherent PN code tracking loop with multi-user detection and simplified multi-path interference cancellation (MPIC) is proposed for direct sequence spread spectrum communications system. A decorrelator decision-feedback detector (DDFD) is first applied on the incoming signal to mitigate the multi-user interference. Then, a simplified multi-path interference cancellation (MPIC) is further used to increase signal quality. Finally, a modified code tracking loop (MCTL) is adopted for non-coherent PN code tracking. Mathematical expressions of the S-curve and tracking jitter are derived. Mean time to lose lock is also compared with traditional tracking loops.
From the numerical results, we know the proposed PN code tracking loop can efficiently mitigate the interference from multi-user and multi-path and improve the performance of code tracking loop.
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Mathematical Modelling of The Global Positioning System Tracking SignalsMama, Mounchili January 2008 (has links)
Recently, there has been increasing interest within the potential user community of Global Positioning System (GPS) for high precision navigation problems such as aircraft non precision approach, river and harbor navigation, real-time or kinematic surveying. In view of more and more GPS applications, the reliability of GPS is at this issue. The Global Positioning System (GPS) is a space-based radio navigation system that provides consistent positioning, navigation, and timing services to civilian users on a continuous worldwide basis. The GPS system receiver provides exact location and time information for an unlimited number of users in all weather, day and night, anywhere in the world. The work in this thesis will mainly focuss on how to model a Mathematical expression for tracking GPS Signal using Phase Locked Loop filter receiver. Mathematical formulation of the filter are of two types: the first order and the second order loops are tested successively in order to find out a compromised on which one best provide a zero steady state error that will likely minimize noise bandwidth to tracks frequency modulated signal and returns the phase comparator characteristic to the null point. Then the Z-transform is used to build a phase-locked loop in software for digitized data. Finally, a Numerical Methods approach is developed using either MATLAB or Mathematica containing the package for Gaussian elimination to provide the exact location or the tracking of a GPS in the space for a given a coarse/acquisition (C/A) code.
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Electromagnetic analysis of ground multipath for satellite-based positioning systemsAloi, Daniel N. January 1996 (has links)
No description available.
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High Accuracy GPS Phase Tracking Under Signal DistortionKalyanaraman, Sai K. 18 September 2009 (has links)
No description available.
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