I. Vaughan’s research while affiliated with University of Queensland and other places

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Publications (19)


Intercepting Beam-Agile Radar
  • Conference Paper

August 2018

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38 Reads

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6 Citations

I. Vaughan

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Late-time resonance window estimation in radar

December 2013

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19 Reads

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5 Citations

Radar target identification based on resonant frequencies requires analysis of the “late-time” portion of the target signature: the period when early-time scattering has ceased, the resonant frequencies are well established, and the signal can still be distinguished from the noise. While target geometry can be used to determine the late-time commencement, for uncooperative radar target identification the determination must be made on the basis of the signal data alone. Intrinsic features of the Hankel matrix of the target impulse response, such as its rank and the distribution of its singular values, can be used to identify the late-time start prior to full matrix-pencil analysis of the optimal processing window. Results are presented from simulated target data.


Satellite transmitter position constraints for zero, one and two solutions

December 2013

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13 Reads

In a satellite navigation system such as the Global Positioning System (GPS), the receiver is required to determine its position accurately from time-difference-of-arrival (TDOA) measurements of incident signals. We will examine the receiver solution space of an estimator which is maximum-likelihood under the assumption of Gaussian measurement errors. We find the satellite position constraints which cause the receiver to have zero, one or two real solutions. We derive the equations for the boundary between the domains in which one and two solutions lie and find that there is a simple geometric interpretation.


Approximate lattice detection in MIMO communications using Jacobi theta functions

January 2008

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16 Reads

We consider a multiple-input, multiple-output (MIMO) communication system in which data streams are independently transmitted over a number of antennas and collectively decoded from a number of receiving antennas. The maximum-likelihood (ML) or sphere decoder is known to yield the lowest symbol error rate (SER). However, in the worst case, complexity is exponential in the number of antennas. Seeking to reduce complexity without greatly increasing the SER, we propose an approximate lattice decoder with polynomial arithmetic complexity. The decoder performs unconstrained nonlinear optimisation of a Jacobi theta function that approximates the log-likelihood function. Simulations demonstrate that this decoder performs nearly as well as the sphere decoder in terms of bit error rate (BER) and shows a significant performance enhancement compared to linear and lattice-reduced cancellers.


A statistical analysis of the Delogne-Kasa method for fitting circles

September 2006

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304 Reads

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38 Citations

Digital Signal Processing

In this paper, we examine the problem of fitting a circle to a set of noisy measurements of points on the circle's circumference. Delogne (Proc. IMEKO-Symp. Microwave Measurements 1972, 117-123) has proposed an estimator which has been shown by Kasa (IEEE Trans. Instrum. Meas. 25, 1976, 8-14) to be convenient for its ease of analysis and computation. Using Chan's circular functional model to describe the distribution of points, we perform a statistical analysis of the estimate of the circle's centre, assuming independent, identically distributed Gaussian measurement errors. We examine the existence of the mean and variance of the estimator for fixed sample sizes. We find that the mean exists when the number of sample points is greater than 3 and the variance exists when this number is greater than 4. We also derive approximations for the mean and variance for fixed sample sizes when the noise variance is small. We find that the bias approaches zero as the noise variance diminishes and that the variance approaches the Cramer-Rao lower bound.


Efficient initialisation of lattice multicarrier modulation

February 2005

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8 Reads

Recently, a novel transmission technique was proposed for delay-spread channels that guarantees a low peak-to-average power ratio while also having low computational complexity. In this paper, we extend the technique to systems where the symbol length or number of parallel channels is large, such as in very high speed digital subscriber line (VDSL) or multiple-input multiple-output (MIMO) systems respectively. While operational complexity is low, the computational cost of initialisation in a VDSL or MIMO channel appears, at first sight, to be prohibitive. We show that initialisation can be carried out efficiently. Having so enabled the technique, we present simulation results in a MIMO-VDSL environment which demonstrate its superiority in comparison to other popular techniques such as V-DMT and DMMT when clipping in the transmit power amplifier is a dominant consideration


Citations (8)


... Hunde et al. [19] discuss a multi-target tracking system that addresses target initiation and termination processes with automatic track management feature. Vaughan et al. [20] conduct a statistical analysis that yields an accurate approximation of the false-track and track detection probabilities as a function of the threshold on the track-initiation statistic. Han et al. [21] propose a novel track initiation algorithm based on agglomerated hierarchical clustering and association coefficients. ...

Reference:

Multi-Target Track Initiation in Heavy Clutter
Tracker Operating Characteristic for Integrated Probabilistic Data Association
  • Citing Conference Paper
  • August 2018

... Thus, if F u has orthonormal columns, F H u r uc = d u + F H u w uc approximately recovers d u . The weighted power in (13) becomes P W = tr{G H A W GC} = tr{F H u Z H A W ZF u } + tr{R H pt A W R pt C pt }, which is minimized over the set of semiunitary matrices when F u comprises the K u least eigenvectors of Z H A W Z. Since F u has orthonormal columns, the products F u d u (at the transmitter) and F H u r uc (at the receiver) can be efficiently performed by resorting to Householder reflectors [41], taking 2K u K c + K 2 c complex multiplications each. ...

Orthogonal precoding for sidelobe suppression in DFT-based systems using block reflectors
  • Citing Conference Paper
  • March 2017

... Recent literature provides methods to estimate the latetime response broadly based on three approaches namely Auto-Regressive (AR) filter-based approach [3], based on the formation of the Hankel matrix using the target scattered response [4], [5], [6], and Short-Time Matrix Pencil Method (ST-MPM) [2], [7]. All approaches provide a way to estimate the beginning of the late-time response without prior knowledge of the target geometry of orientation to improve the accuracy of resonance-based radar target recognition. ...

Late-time resonance window estimation in radar
  • Citing Conference Paper
  • December 2013

... This method is not sensitive to outliers and it is relatively easy to implement. An example of a robust method is the Hough transform, which is mainly used in digital imaging [13], full LS, reduced LS, and modified LS [1], and Delogne-Kasa for noisy data [17]. When fitting a circle, the LS methods result in non-linear and implicit equations that can only be solved numerically, often following linearization techniques [4]. ...

A statistical analysis of the Delogne-Kasa method for fitting circles
  • Citing Article
  • September 2006

Digital Signal Processing

... The standard and desired pulse trains are applied to the counters and a measure of the desired frequency is obtained by multiplying the known standard frequency by the ratio between the desired count and the standard count obtained in the two digital counters [6,8]. The coincidence of pulses has been investigated over the last sixty years161718192021. In these works, is shown the connections of the coincidence of pulse of regular independent pulse trains with the number theory, particularly with linear congruence theory1617 and Diophantine approximations2021. ...

Errata In Number Theoretic Solutions To Intercept Time Problems
  • Citing Article
  • December 1997

IEEE Transactions on Information Theory

... For instance, if k i are generated from the Bernoulli missing model, which is frequently assumed in Refs. [7][8][9][10][11][12][13] , then the expected value of jSðfÞj 2 is given by 7 ...

Estimating The Period Of A Pulse Train From A Set Of Sparse, Noisy Measurements
  • Citing Article
  • Full-text available
  • January 1997