Samuel Picton Drake

Flinders University · College of Science and Engineering

Referring to the very epitome of physics as an engineer may appear humorous. However, there is a serious case for it. What would you call somebody who worked in a patent office as a technical expert for seven years, held a number of patents himself on refrigeration, self-adjusting cameras, and electric motors, and explained the photoelectric effect...

It is generally believed that special relativistic effects are important only when studying objects moving at speeds close to that of light. This belief leaves many practicing scientists and engineers with the impression that an understanding of relativity is not necessary for their day jobs. Our aim is to show that the ideas and mathematics of the...

The formation of energetic rings of matter in a Kerr spacetime with an outward pointing acceleration field does not appear to have previously been noted as a relativistic effect. In this paper we show that such rings are a gravimagneto effect with no Newtonian analog, and that they do not occur in the static limit. The energy efficiency of these ri...

In complex electromagnetic environments it can often be difficult to determine whether signals received by an antenna array emanated from the same source. The failure to appropriately assign signal reception events to the correct emission event makes accurate localisation of the signal source impossible. In this paper we show that as the received s...

In this paper we show how the student can be led to an understanding of the connection between special relativity and general relativity by considering the time dilation effect of clocks placed on the surface of the Earth. This paper is written as a Socratic dialog between a lecturer Sam and a student Kim. Comment: 8 pages, 1 figure, uses the revte...

An algorithm is presented to determine the number and direction of multiple indistinguishable radio frequency emitters using a single channel circular antenna array. This algorithm combines pseudo-Doppler direction finding with the MUSIC algorithm. The theory is provided along with a simulation. The simulation shows that the algorithm performs very...

The bond-graph (BG) enables to model multi-physics systems in the energy domains. This paper shows that BG models are an alternative, more intuitive and simpler to interpret, graphical tool as compared to existing dynamic models for performance prediction of the line-start permanent-magnet synchronous motors (LSPMSMs). It includes electrical, magne...

In "stand-off" scenarios an estimate of the bearing to an emitter can be easily calculated from measurements of the received frequency, position and velocity of receivers. This technique is only effective if the measured frequencies can be reliably associated with a single emitter that is far away. We show how to determine if the receivers' measure...

We discuss our progress towards creating a computer model of a quantum illumination type quantum radar. This will allow us to determine the quantum advantage from several important initial experimental demonstrations.

In this paper, we present an algorithm for determining a curve on the earth's terrain on which a stationary emitter must lie according to a single Doppler shift measured on an unmanned aerial vehicle (UAV) or a low earth orbit satellite (LEOS). The mobile vehicle measures the Doppler shift and uses it to build equations for a particular right circu...

A formula for the transformation of phase velocity between two inertial observers is given. This is a correction of the formula provided by R. A. Bachman in Am. J. Phys. 57(7), 628-630 (1989), in which the transformation of the phase velocity perpendicular to the relative velocity of the two frames was incorrectly stated.

The first project report for the Efficient Generation and Evolution of Probability Density Maps project is reproduced here as a Defence Science and Technology Group technical report. Here we consider the application and suitability of the Joint Photographic Experts Group (JPEG) compression method and a simpler approach to Discrete Probability Densi...

The second project report for the Efficient Generation and Evolution of Probability Density Maps project is reproduced as a Defence Science and Technology Group technical report. Here we focus on solving the Schrödinger equation numerically for several simple potentials using Fourier and Chebyshev pseudo-spectral methods. The report has been writte...

For a flying military vehicle, avoiding detection can be a key objective. To achieve this, flying the least-probability-of-detection path from A to B through a field of detectors is a fundamental strategy. While most of the previous optimization models aim to minimize the cumulative radar exposure, this paper derives a model that can directly minim...

In this paper, we explicate the suggested benefits of Clifford's geometric algebra (GA) when applied to the field of electrical engineering. Engineers are always interested in keeping formulas as simple or compact as possible, and we illustrate that geometric algebra does provide such a simplified representation in many cases. We also demonstrate a...

For a flying military vehicle, avoiding detection can be a key objective. To achieve this, flying the least-probability-of-detection path from A to B through a field of detectors is a fundamental strategy. While most of the previous optimization models aim to minimize the cumulative radar exposure, this paper derives a model that can directly minim...

In previous work a method was proposed to determine the bias in localization algorithms using range or bearing data. In this paper the method is extended to be more generic; in particular, different types of measurement data are permitted, and there may be more measurements than there are variables to estimate. The method combines the Taylor series...

In passive target localization using direction finding (DF), there are particular sensor-target placements that cause large biases in the estimates or the failure of estimates to converge to a unique solution. Identification of such problematic configurations is crucial for implementing estimation and tracking algorithms effectively. In this paper...

This paper is concerned with real-time optimal UAV path planning in a multi-emitter geolocation environment. All UAVs are assumed to be controlled by a central processing unit. A UAV waypoint-update/steering algorithm is developed based on maximizing the determinant of Fisher information matrix for localization of stationary emitters. Soft and hard...

Tensor algebra and tensor calculus are widely used in the the fields of mathematics and physics but their usefulness in estimation theory has not been widely appreciated. In this paper we give a short introduction to tensor algebra and provide a few examples of how to use it. None of the results presented in this paper are original but they are nov...

Unmanned aerial vehicles (UAVs) are used in team for detecting targets and keeping them in its sensor range. There are various algorithms available for searching and monitoring targets. The complexity of the search algorithm increases if the number of nodes is increased. This paper focuses on multi UAVs path planning and Path Finding algorithms. Nu...

DSTO Australia concluded a two year research program in March 2006 that demonstrated distributed, autonomous, self-organising stand-in sensor and effector systems. This paper describes research activities from this program including the development of miniaturised sensor and effector payloads, the development of novel algorithms for the fusion of d...

One vision for the future battlespace comprises cooperatives of uninhabited vehicles working seamlessly together and with manned vehicles in an adversarial environment. This provides the future warfighter with the potential to extend his reach and access into areas intentionally denied to him. Realisation of this vision clearly requires significant...

Exploiting Uninhabited Aerial Vehicle (UAV) sensors to augment data available from a ground based sensor system for enhancing operator situational awareness was one of the technological advances in distributed sensing demonstrated during a field trial held at Woomera in early July 2005. Electronic Support (ES) sensors aboard two UAVs and one ground...

Modern day electronic warfare often contains a heterogeneous mix of distributed sensors. This mix of sensors provides information about the probability of emitters being located at certain points. This discrete probability map (DPM) must be reported to the commander or some other decision maker in a timely fashion. This report shows that with respe...

The Defence Science & Technology Organisation (DSTO), which is part of the Australian Department of Defence, is developing a research capability that uses small, inexpensive, autonomous uninhabited air vehicles (UAVs) to detect, identify, target, track, and electronically engage ground-based targets such as radars. The UAVs, which act autonomously...

Unmanned aerial vehicles (UAVs) are increasingly used in military and scientific research. Some miniaturized UAVs rely entirely on the Global Positioning System (GPS) for navigation. GPS is vulnerable to accidental or deliberate interference that can cause it to fail. It is not unusual, even in a benign environment, for a GPS outage to occur for pe...

In this paper we study a scenario in which uninhabited aerial vehicles (UAVs) are tasked with locating a group of active emitters. The time difference of arrival (TDOA) technique is used by the UAVs to geolocate the active emitters. As TDOA requires at least three UAVs to perform geolocation, an algorithm to team three or more UAVs and task this te...

This paper presents bias reduction techniques for the scan-based least-squares emitter localization algorithm. Scan-based emitter localization exploits constant scan rate of the radar antenna main beam to allow determi-nation of the emitter location by three or more receivers. It does away with high-precision timing requirements for time of arrival...

The novel approach to geolocation by time difference of arrival (TDOA) taken in this paper is the introduction of prolate spheroidal coordinates. In these coordinates the nonlinear TDOA equations simplify greatly and in the far-field the TDOA equations become linear. A new method for solving the non-linear TDOA equations is proposed which we refer...

This paper describes an algorithm that has been used for the autonomous control of multiple UAVs tasked with the high level objective of locating a radar subject to a number of real world constraints. The distributed, fully autonomous, cooperative control of the multiple UAV system was executed using sensor input from a heterogenous network of mini...

The paper proposes a new simplified algorithm to estimate the location of an emitter by utilizing time difference of arrival (TDOA) measurements. This is achieved by recasting the estimation problem in prolate spheroidal coordinates. Prolate spheroidal coordinates greatly simplify the TDOA equations, producing a set of linear equations in the far f...

The Defence Science & Technology Organisation (DSTO), which is part of Australia's Department of Defence, has embarked upon a whole-of-Defence priority initiative, known as the Automation of the Battlespace Initiative (ABSI). ABSI is directed towards achieving three interlinked and enduring objectives: leveraging the warfighter in an environment of...

Determining the location of radar emitters is one of the most important categories of search problems for defence related tasks. Autonomous Air Vehicles (AAVs) that are equipped with electronic support (ES) sensor systems, provide a means of extending search capabilities beyond the visual horizon and detecting such emitters. However; detection alon...

In many applications relevant to the Australian Defence Force (ADF) it is necessary to convert the Global Positioning System (GPS) coordinates of latitude, longitude and height to a local navigation frame with coordinates, east, north and up. For example when testing navigation instruments, such as the inertial navigation system (INS), it is often...

In many applications relevant to the Australian Defence Force (ADF) it is necessaryto convert the Global Positioning System (GPS) coordinates of latitude, longitude and height to a local navigation frame with coordinates, east, north and up. For example when testing navigation instruments, such as the inertial navigation system (INS), it is often h...

After the original discovery of the Kerr metric, Newman and Janis showed that this solution could be derived by making an elementary complex transformation to the Schwarzschild solution. The same method was then used to obtain a new stationary axisymmetric solution to Einstein's field equations now known as the Kerr–Newman metric, representing a ro...

In this paper we present a class of metrics to be considered as new possible sources for the Kerr metric. These new solutions are generated by applying the Newman-Janis algorithm (NJA) to any static spherically symmetric (SSS) ``seed'' metric. The continuity conditions for joining any two of these new metrics is presented. A specific analysis of th...

The study of chaos in relativistic systems (both special and general) is a newly emergent field. The main focus of this paper is the study of the chaotic trajectories of a charged particle in a static electric field. The full special relativistic equations of motion are used. Here we concentrate on motion in a field that is produced by two fixed ce...

The study of chaos in relativistic systems (both special and general) is a newly emergent field. The main focus of this paper is the study of the chaotic trajectories of a charged particle in a static electric field. The full special relativistic equations of motion are used. Here we concentrate on motion in a field that is produced by two fixed ce...