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Rankin G.A.,University of Adelaide | Tirkel A.Z.,Scientific Technology
International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz | Year: 2014

In previous work, we have studied thermal and behavioral effects and the detection of termites by millimeter waves. Motivated by the intriguing possibilities of millimeter wave - cellular, and higher level, biological interactions, we have investigated the design of an acupuncture-like needle for efficient delivery of millimeter waves through the skin. Contrary to conventional knowledge, a bare conductor can sustain two dominant modes: the well-known symmetric TM01 mode, and the hitherto overlooked asymmetrical HE11 mode. Here, we present a convertor for the excitation of the HE11 mode on a conductor. © 2014 IEEE.

Rankin G.,University of Adelaide | Tirkel A.,Scientific Technology | Leukhin A.,Mari State University
Proceedings International Radar Symposium | Year: 2015

High resolution imaging radars at millimeter-wave frequencies for obstacle avoidance for Unmanned Aerial Vehicles (UAV) utilize a large antenna aperture and sequential mechanical scanning of the aperture to form images with high fidelity. Planar arrays are an attractive alternative. They do not require mechanical scanning, and images are formed digitally using beamforming techniques [1]. To achieve image quality comparable to mechanically scanned radars, fully populated arrays require inordinate numbers of elements. These are costly, a challenge to design, and difficult to produce. Thinned or sparse arrays are a potential solution to this problem. MIMO (Multiple Input Multiple Output) techniques are an efficient method of thinning an array using spreading sequences to create an overlay of paired transmitter and receiver elements, without sacrificing image quality. The use of MIMO techniques to thin an array is a relatively recent development [2]. To be of practical use at millimeter-wave frequencies, MIMO techniques require the development of novel array geometries and architecture. This paper presents designs for the implementation of millimeter-wave planar arrays which have been thinned using MIMO techniques and considerers the limitations on the length of spreading sequences due to the increasingly pronounced effect of Doppler at higher frequencies. These considerations have led to the first instance of the use of the Moreno-Tirkel sequence Family B for high resolution imaging radar. © 2015 German Institute of Navigation (DGON).

Moreno O.,Gauss Research Laboratory Inc. | Tirkel A.Z.,Scientific Technology | Parampalli U.,University of Melbourne | Van Schyndel R.G.,RMIT University
Electronics Letters | Year: 2010

A new construction of arrays for watermarking is presented. The arrays are composed from cyclic shifts of a binary column with good autocorrelation. The sequence of shifts is obtained from a discrete logarithm of an irreducible quadratic over a finite field. This yields a large family of binary arrays with low off-peak autocorrelation and low cross-correlation in many new and desirable sizes. © 2010 The Institution of Engineering and Technology.

Moreno O.,Gauss Research Laboratory Inc. | Tirkel A.,Scientific Technology
IEEE International Symposium on Information Theory - Proceedings | Year: 2011

This paper presents two new classes of families of multi-periodic arrays suitable for digital watermarking. These families are large and all arrays have good auto and cross-correlation, and are available in many sizes. The construction is based on log quadratic and exponential quadratic maps. The maps applied to elements in an extension field on a natural multi-dimensional grid. The grid also leads to a generalized multi-dimensional Legendre array, which can be used in the family constructions. © 2011 IEEE.

Ortiz-Ubarri J.,University of Puerto Rico at San Juan | Moreno O.,Gauss Research Laboratory Inc. | Tirkel A.,Scientific Technology
2011 IEEE Information Theory Workshop, ITW 2011 | Year: 2011

New families of three-dimensional (3-D) optical orthogonal codes for applications to optical code-division multiple access (OCDMA) networks are proposed. The families are based in the three dimensional periodic Welch Costas array over elementary Abelian groups. These new families are shown to be asymptotically optimal through the Johnson bound. © 2011 IEEE.

Tirkel A.Z.,Scientific Technology | Hall T.E.,Monash University | Osborne C.F.,Monash University | Meinhold N.,79 Old Healesville Rd | Moreno O.,Gauss Research Laboratory
ACM International Conference Proceeding Series | Year: 2011

Digital fingerprinting is a technique for tracing the distribution of multimedia content, and protecting it from unauthorized manipulation. Unique identification information is embedded into each distributed copy of the signal. In a collusion attack, fingerprints are combined to remove or distort the fingerprints. Audio signals are good candidates for fingerprinting, because of the forgiving nature of the human auditory system to cross-talk between channels. We use principal components of the audio signal to construct an abstract vector space. The fingerprints are ordered rotations in that space. The rotations are determined by arrays with good correlation properties. These arrays are embedded in real audio, and are imperceptible, according to a panel of experts. These fingerprints are resistant to an averaging collusion attack by hundreds or thousands of colluders, and can withstand a worst case RandNeg attack by up to 30 colluders. © 2011 ACM.

Tirkel A.,Scientific Technology | Cavy B.,PolytechNantes | Svalbe I.,Monash University
Electronics Letters | Year: 2015

Families of sequences with low off-peak autocorrelation and low crosscorrelation are highly valued in spread-spectrum communication. Digital watermarking has an equal need for diverse families of orthogonal multi-dimensional (nD) arrays, where each array has optimal correlation properties. In this reported work, a 1D discrete projection method is used to construct new families of nD orthogonal arrays of size pn, with p a 4k - 1 prime. Finite field algebra and Hadamard matrices are applied to analyse these arrays. The periodic autocorrelation of each array is 'perfect' (p2 - 1 peak value, with -1 off-peak for p × p arrays). The cross-correlation between any pair of the p members of each 2D family has the lowest possible values, 0 or ±p. The arrays can be synthesised for arbitrarily large p and outperform Kasami sequences. The alphabet values for these optimal arrays can be roots of unity or signed integers. The aperiodic autocorrelation of the p × p arrays can attain a merit factor of above 3 at shift (p/4, p/4), consistent with Golay's conjecture in 1D. © The Institution of Engineering and Technology 2015.

le Marshall N.W.D.,University of New South Wales | Tirkel A.Z.,Scientific Technology
Progress In Electromagnetics Research C | Year: 2010

Non-invasive termite detection avoids damage to the structure under investigation. In this paper, we present the design and simulation of a hybrid radar array, with sub-arrays designed for both close range imaging and wide-area direction of arrival (DOA) processing for non-invasive termite detection. This radar array achieves wide area detection via novel modifications to the Matrix Enhanced Matrix Pencil algorithm and array transformation and achieves high resolution imaging through near field beam-steering from a large random array. The array hardware is designed to be implemented using available technology and low cost electronics.

Le Marshall N.W.D.,University of New South Wales | Tirkel A.Z.,Scientific Technology
Progress In Electromagnetics Research B | Year: 2011

In this paper, we describe the design of a hybrid 24 GHz RADAR array for termite detection and imaging. The array uses MIMO techniques to provide transmit beam steering and null steering in conjunction with the Matrix Enhanced Matrix Pencil (MEMP), which provides direction of arrival processing. We describe the selection of our MIMO orthogonal codes and test their suitability. Simulated results are shown for our array design and MIMO processing in a range of applications MIMO enables us to produce flexible nulling and beam steering for our transmitter array as well as reducing multipath reflections and narrowband interference. MIMO processing also produces large time savings, enabling longer, more accurate acquisitions which can increase SNR. Transmitter beam-forming, produces an SNR improvement of 18.2 dB and can be used to reject clutter by up to 20 dB. Flexible nulling can reject interferers still further.

Le Marshall N.,Australian Defence Force Academy | Rankin G.,EWA Australia | Tirkel A.,Scientific Technology
2010 IEEE Radio and Wireless Symposium, RWW 2010 - Paper Digest | Year: 2010

This paper describes a 24 GHz radar receiver array, designed to detect and image termite activity, behind a wall, floor or ceiling. This hybrid array is composed of two sub-arrays. A Direction of Arrival (DOA) sub-array for wide area detection of termites, and a 3D high resolution imaging sub-array for imaging individual termites. Here, we introduce an enhanced DOA algorithm, to resolve arbitrary numbers of targets, and compare simulation results with video of actual termites. © 2010 IEEE.

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