DSTO Publications Online

Synthetic Electronic Imaging System.

Sun, 28 Jun 2009 22:58:59 GMT

Title: Synthetic Electronic Imaging System.

Authors: Ide, K.M.; Jarvis, B.J.; Lucas, M.A.

Abstract: The Synthetic Electronic Imaging System employs electronic components to combine multiple images from a plurality of cameras which are processed with inertial data from the vehicle on which the system is mounted to yield stabilised video images without resorting to complicated optics or a stabilised platform. It was devised as an alternative to stabilised ball turrets fitted with electro-optic and infrared cameras. Intended as an imaging system for Unmanned Aerial Vehicles (UAV), it may be employed in any manned or Unmanned System (UMS) where situation awareness is aided by the use of an imaging system. This report describes the development of the Synthetic Electronic Imaging System and assembly of a simple concept demonstrator in 2005.

Executive summary: Conventional ball turret imaging systems are mechanically complex requiring continued calibration and maintenance. Hence, their purchase and support involves significant costs. The dimensions and weight of a ball turret demand an airframe with significant payload capacity. These restrictions led the authors to develop the Synthetic Electronic Imaging System. It is a highly capable alternative but without the complexity, cost and support necessary for a comparable ball turret imaging system. The Synthetic Electronic Imaging System employs electronic components to combine multiple images from a plurality of cameras which are processed with inertial data from the vehicle on which the system is mounted to yield stabilised video images without resorting to complicated optics or a stabilised platform. A full field of view wide angle composite image is displayed on one monitor with a box overlay representing the region of interest. A second monitor shows a telephoto image within the designated region of interest. As the operator moves the region of interest, images in the second display are updated in real-time. The two complementary video streams provide an excellent aid to situation awareness and analysis. The two video channels are transmitted to the Ground Control Station as television images requiring very low bandwidth. Operators can “time-slip” the video images by using Digital Video Recorder software controls for review and analysis. Frames that merit further analysis or examination can be downloaded from the remote vehicle as a series of still images with the maximum resolution of the sensor. Intended as an imaging system for Unmanned Aerial Vehicles, it may be employed in any manned or Unmanned System where situation awareness is aided by the use of an imaging system. This report describes the development of the Synthetic Electronic Imaging System and assembly of a simple concept demonstrator in 2005.

Giselle: A Mutually Orthogonal Triple Twin-loop Ground-symmetrical Broadband Receiving Antenna for the HF Band.

Sun, 28 Jun 2009 22:58:59 GMT

Title: Giselle: A Mutually Orthogonal Triple Twin-loop Ground-symmetrical Broadband Receiving Antenna for the HF Band.

Authors: Martinsen, W.

Abstract: This report describes development of a tri-axial mutually orthogonal broadband twin-loopreceiving antenna for the HF band. The three twin-loops have been arranged so that they exhibitthe same distributed parameters between themselves and ground. The upper frequency limit ofthe antenna is discussed and a method for extending the low frequency cut-off is presented. Theantenna noise factor is calculated from measured data.

Executive summary: Traditional mutually orthogonal tri-axial loop antennas have distributed parameters to theground that are not consistent between the three loops. This non-symmetricalcharacteristic adds complexity to the analysis of signals received from each of the loops.Also, the distributed inductance (L) and capacitance (C) of each loop form a resonantcircuit limiting the loop’s usefulness for broadband work.The tri-axial twin-loop antenna design presented in this report has the same distributedparameters to ground on all three loops (ground-symmetrical) easing the analysis burdenon the received data. The final version of the antenna presented can cover the complete HFband and is ideal for studying the polarisation of received signals with the view ofmitigating HF polarisation fading.The inherent noise produced by the Giselle antenna is less than the expected man-madenoise for a quiet rural site; therefore the Giselle antenna can also be used as a compact triaxialpolarisation diversity surveillance antenna for the whole of the HF band. It is capableof discriminating between locally transmitted ground wave signals and those transmittedat some distance and received via sky-wave by monitoring for any signs of rotation in thereceived signal’s polarisation.

Survey of Knowledge Representation and Reasoning Systems.

Sun, 28 Jun 2009 22:58:59 GMT

Title: Survey of Knowledge Representation and Reasoning Systems.

Authors: Trentelman, K.

Abstract: As part of the information fusion task we wish to automatically fuse informationderived from the text extraction process with data from a structuredknowledge base. This process will involve resolving, aggregating, integratingand abstracting information - via the methodologies of Knowledge Representationand Reasoning - into a single comprehensive description of an individualor event. This report surveys the key principles underlying research in thefield of Knowledge Representation and Reasoning. It represents an initial stepin deciding upon a Knowledge Representation and Reasoning system for ourinformation fusion task.

Executive summary: As part of the information fusion task we wish to automatically fuse information derivedfrom the text extraction process with data from a structured knowledge base. This processwill involve resolving, aggregating, integrating and abstracting information - via themethodologies of Knowledge Representation and Reasoning - into a single comprehensivedescription of an individual or event. This report surveys the key principles underlyingresearch in the field of Knowledge Representation and Reasoning. It represents aninitial step in deciding upon a Knowledge Representation and Reasoning system for ourinformation fusion task.We find that although first-order logic is a highly expressive knowledge representationlanguage, a major drawback of the logic as a Knowledge Representation and Reasoningsystem for our information fusion task is its undecidability. Moreover, most first-order automatedtheorem provers are not designed for large knowledge-based applications. Modallogics are gradually receiving more attention by the Artificial Intelligence community,but research in modal logics for knowledge representation still has a long way to go. Aproduction rule (expert) system is viable as a Knowledge Representation and Reasoningsystem, but these systems are optimally suited for small, specific domains. To build anintelligence expert system we would require expert knowledge in pretty much everything.Frame systems are limited in their expressiveness, and moreover - in regards to knowledgerepresentation - have been superceded by description logics. Semantic networks are excellentfor taxonomies, but are not particularly suitable for our information fusion task. Ona more positive note, description logics are currently very popular and are actively beingresearched. They are (in the most part) decidable and their open-world semantics wouldallow us to represent incomplete information. A further advantage is the availability ofSemantic Web technologies. Description logics are still limited however; for our task, we’dneed to look at very expressive logics which might lose us decidability.

Benchmark Testing of Naval Threat Countermeasure Simulation (NTCS) Development from Version 2.4c to 3.2.

Sun, 28 Jun 2009 22:58:59 GMT

Title: Benchmark Testing of Naval Threat Countermeasure Simulation (NTCS) Development from Version 2.4c to 3.2.

Authors: Smith, S.E.

Abstract: The Naval Threat Countermeasure Simulator (NTCS) is a commercial code accepted as the NATO standard for ship Infrared (IR) signature modelling. This code has undergone extensive development, in conjunction with measurement trials, since 1997. A set of benchmark test cases was developed to track the development of NTCS since 1997 paying particular attention to the effect on the computed IR signature of a test target. In this report, the results from these benchmark tests are presented for NTCS versions from 2.4c to 3.2. It will be shown that improvements to the NTCS code from version to version result in significant changes in computed IR signatures. In addition to code changes, other parameters such as choice of environmental data generation software (e.g. LOWTRAN/MODTRAN) and choice of solar scattering flag also influence the computed IR signature. Timing information was also assessed aspart of this study and reveals increases in run-time requirements as NTCS has evolved. In light of these results, caution should be exercised when comparing results from different versions of NTCS. It is also recommended that details of the NTCS version and parameters used are specified when presenting NTCS results.

Executive summary: The Naval Threat Countermeasure Simulator (NTCS) is a commercial code accepted as the NATO standard for ship infrared (IR) signature modelling. This code has undergone extensive development, in conjunction with measurement trials, since 1997. A set of benchmark test cases was developed to track the development of NTCS since 1997 paying particular attention to the effect on the computed IR signature of a test target. In this report, the results from these benchmark tests are presented for NTCS versions from 2.4c to 3.2. In addition to the changes resulting from different version, two other parameters within NTCS were also investigated. The first is the choice of environmental data generation software (e.g. LOWTRAN/MODTRAN) and the second is the choice of the solar scattering flag. These were included since they were changed or added to NTCS within the series of NTCS from 2.4c to 3.2.Improvements to the NTCS code from version to version result in significant changes in computed IR signatures. In addition to code changes, the parameters such as choice of environmental data generation software and choice of solar scattering flag also influence the computed IR signature. Timing information was also assessed during this study and reveals that the run-time requirements for NTCS have increased during the evolution of NTCS. It is recommended that caution is exercised when comparing results from different versions of NTCS. It is also recommended that details of the NTCS version and parameters used are specified when presenting NTCS results. Accurate comparisons of computed IR contrast signature data for different naval platforms can only be made reliably when the same NTCS version is used and the same background, environmental data generation software and solar scattering flag are selected.