Airborne Search Research Articles

Support for the state emergency medical system in the fight against COVID -19 by airborne search and rescue teams of the ASAR service

The COVID-19 pandemic, which undoubtedly left significant imprint in public consciousness,necessitated unprecedented support for medical rescue systems bothin Poland and around the world. During the pandemic, the State Emergency MedicalService in Poland was bolstered with legally available support measures, includingassistance from the Airborne Search and Rescue Teams of ASAR.

Coarse and fine combination technology based on gyrostability and missing target tracking

High-precision, stable tracking technology on a mobile platform is a key technology for realizing the integration of airborne search and tracking. In this study, coarse-fine compound technology based on gyrostabilization and miss tracking is applied. First, the working principle of the coarse and fine composite system is analyzed, and then the coarse and fine composite algorithm is modeled. Thereafter, the error of the coarse and fine composite axis is analyzed, and the precision tracking servo control algorithm is designed. Finally, using the model and algorithm designed to control the single reflector and galvanometer, the coarse tracking of the space target and the fine tracking of the source are completed under the condition that the equivalent sine amplitude is 5 deg and the frequency is 0.2 Hz. At the same time, a test system was built for performance verification. The algorithm achieved a coarse-tracking azimuth-axis tracking accuracy [root mean square (RMS)] of 26.3 μrad and a pitch-axis tracking accuracy (RMS) of 28.9 μrad. After composite tracking was switched on, precision tracking azimuth-axis tracking accuracy (RMS) improved to 7.9 μrad and pitch-axis tracking accuracy (RMS) improved to 6.3 μrad, both better than 10 μrad. This study provides new insights into the stability and precision tracking of single cameras on airborne platforms. At the end of this work, the outdoor experiment to verify the influence of random interference on the system performance under given conditions and the subsequent optimization direction of the system are given.

CsI(Na) Detector Array Characterization for ARES Program

Researchers at Lawrence Berkeley National Laboratory have been supporting the Transformational and Applied Research Directorate in the Domestic Nuclear Detection Office of the Department of Homeland Security to define needs for, to develop, and to test a scintillator-based radiation detection and localization system to be fielded on a helicopter platform - the so-called Airborne Radiological Enhanced-sensor System. The system comprises an array of 92 CsI(Na) detectors that are arranged to function as an active mask to encode the directionality in the roll-dimension of measured gamma rays and is additionally capable of Compton imaging. Additional contextual sensors and specially-developed algorithms are also being fielded for characterization with the goal of detecting, localizing, and helping to interdict radiological and nuclear threats via airborne search. The algorithms that are being developed leverage contextual information including topography, geography, hyperspectral imagery, video tracking, and platform positioning. This paper describes recent characterization efforts of the CsI(Na) detector system including energy, position, and timing resolution and synchronization between the 184 individual photomultiplier tubes.

An orienteering model for the search and rescue problem

In this paper, we propose a new model for the search and rescue problem. We focus on the case of a single airborne search asset through a connected space and continuous time with a maximum travel time $$T$$ . The intent is to maximize the detection of a cooperative target (search and rescue). The proposed model is based on the assumption of existing a priori information (e.g., result of information fusion process) to establish a spatial distribution of probability of containment in possible geographic locations. The possibility area is defined using a cut threshold on the probability of containment and the search path as well as the allocation of the level of effort to each region in the search space is obtained based on an orienteering model. We illustrate the application of the proposed model on an empirical example.

Some aspects of signals in the I.A.F.

Article shall try to tell you something about the Signals Branch of the Indian Air Force, what it aims to do, some of its difficulties and some of the instances where we feel it is not as efficient as we should like it to be. The purpose of an Air Force Signal Organization is to provide communication and radar facilities which will assist the Air Commander to exercise efficient control of his forces and to develop and apply their maximum fighting strength. These various facilities comprise-(a) Wireless communication system, (b) Radio Navigational and runway approach aids, (c) Aircraft control, early warning and identification systems, (d) Airborne search system, (e) Radio warfare system. (d) Airborne search system, (e) Radio warfare system

Cutting Heads or Winning Hearts: Late Colonial Portuguese Counterinsurgency and the Wiriyamu Massacre of 1972

In the early 1970s, Portugal still held on to the oldest European colonial empire, resisting the winds of decolonization in Africa. In this period, the Portuguese were fighting counterinsurgency campaigns in three of its overseas territories: Angola, since 1961; Guinea, since 1963; and Mozambique, since 1964. This article focuses on the counterinsurgency campaign in Mozambique because it was there, in 1972, that the most serious known atrocity took place, at least in terms of its international impact, from these unconventional wars. The appointment of a new commander-in-chief, Kaúlza de Arriaga (1970–73), to Mozambique intensified the war. Larger airborne search and destroy operations were carried out in an attempt to win the campaign quickly and decisively. It was in this context that the killing of civilians took place somewhere around the town of Tete in December 1972, which was eventually followed by an international outcry in response to its public denunciation by Catholic missionaries. The exact location, even the existence of Wiriyamu, as well as the extent of the atrocities, remain contentious. This article will use multiple sources to clarify as far as possible: what happened, why it happened, and its implications for the dynamics of counterinsurgency and intra-state wars generically. Furthermore, it will address specifically what it meant for the Portuguese way in counterinsurgency, until the rapid end of multiple campaigns as a result of a military coup in April 1974, in which Mozambique and the stain of Wiriyamu loomed large.

Experiments and Algorithms to Detect Snow Avalanche Victims Using Airborne Ground-Penetrating Radar

Snow avalanche victims have only a good chance to survive when they are located within a short time. This requires an active beacon for them to wear or a very rapid deployment of a search-and-rescue team with dogs. Customary ground-penetrating radar (GPR) instruments used on the snow surface are not able to reduce fatality numbers because they are slow to search a field. A potential alternative could be an airborne search using radar. An airborne radar search is technologically challenging because a very large data stream has to be processed and visualized in real time, and the interaction of the electromagnetic waves with snow, subsurface, and objects must be understood. We studied a two-step algorithm to locate avalanche victims in real time. The algorithm was validated using realistic test arrangements and conditions using an aerial tramway. The distance dependence of the reflection energy with increased flight heights, the coherence between the use of more antennas and the detectable range, and the reflection images of different avalanche victims were measured. The algorithm detected an object for each investigated case, where the reflection energy of the scans was higher than for the scans of pure snow. Airborne GPR has a large potential to become a rapid search method in dry snow avalanches. However, a fully operational version still requires substantial improvements in hardware and software.

Reference Frame Congruency in Search-and-Rescue Tasks

Our aim was to investigate how the congruency between visual displays and auditory cues affects performance on various spatial tasks. Previous studies have demonstrated that spatial auditory cues, when combined with visual displays, can enhance performance and decrease workload. However, this facilitation was achieved only when auditory cues shared a common reference frame (RF) with the visual display. In complex and dynamic environments, such as airborne search and rescue (SAR), it is often difficult to ensure such congruency. In a simulated SAR operation, participants performed three spatial tasks: target search, target localization, and target recall. The interface consisted of the camera view of the terrain from the aircraft-mounted sensor, a map of the area flown over, a joystick that controlled the sensor, and a mouse. Auditory cues were used to indicate target location. While flying in the scenario, participants searched for targets, identified their locations in one of two coordinate systems, and memorized their location relative to the terrain layout. Congruent cues produced the fastest and most accurate performance. Performance advantages were observed even with incongruent cues relative to neutral cues, and egocentric cues were more effective than exocentric cues. Although the congruent cues are most effective, in cases in which the same cue is used across spatial tasks, egocentric cues are a better choice than exocentric cues. Egocentric auditory cues should be used in display design for tasks that involve RF transformations, such as SAR, air traffic control, and unmanned aerial vehicle operations.

Fast Risley prisms camera steering system: calibration and image distortions correction through the use of a three-dimensional refraction model

To improve airborne search and rescue operations and the general aerial surveillance efficiency, new concepts of multiple field-of-view and variable-resolution imagers have been developed. These imagers provide surveillance operators with simultaneous wide area coverage and high-resolution imaging. Over the last years, several optical steering systems have been developed and field tested in operational conditions. These developments helped us to develop a novel camera steering system using achromatic Risley prisms. This simple and sturdy steering system allowed us to move rapidly and precisely the field of view of an infrared camera. To improve its performance, a three-dimensional (3D) refraction model was applied to enable fast pointing direction calibration and correction of distorted images. Image deformations were analyzed, and a fast linear image correction based on homographic transformation and the 3D refraction model are presented. Experimental results of mosaicking applications with real imaging systems in the 3- to 5-µm, 8- to 12-µm infrared, and 850- to 860-nm visible bands demonstrate the improvements achieved with the homographic image distortions correction and the fast pointing calibration procedure.

Sensor Control Effectiveness and Display Design in an Imaging System for Airborne Search and Rescue

Traditionally, search and rescue (SAR) technicians have conducted search by directly viewing the terrain below the aircraft. Defence R&D Canada is developing a multi-sensor imaging system for SAR that would replace direct inspection under low visibility conditions. The operators may orient the sensors in any direction, which combined with a narrow field-of-view may induce disorientation. In addition to detecting and discriminating objects within the sensor's field-of-view, an operator is responsible for moving the sensor in such a way as to ensure that this detection and discrimination may be carried out with similar effectiveness across the entire area that needs to be searched. The present study reports the development of a metric of coverage effectiveness, and its application to two simulation experiments. The results demonstrate a trade-off between the availability of a moving-map display necessary to preserve operator orientation, and the effectiveness of an operator's sensor coverage over a specific region. That is, sensor control effectiveness was compromised by the addition of a moving-map to the display, likely due to operators' inability to simultaneously inspect the map and move the sensor appropriately. The coverage effectiveness metric reported here would be a useful tool in the development and evaluation of “smart” automation of this sensor sweep function.

Coordinated search for a lost target in a Bayesian world

This paper describes a decentralized Bayesian approach to the problem of coordinating multiple autonomous sensor platforms searching for a single non-evading target. In this architecture, each decision maker builds an equivalent representation of the probability density function (PDF) of the target state through a general decentralized Bayesian sensor network, enabling them to coordinate their actions without exchanging any information about their plans. The advantage of the approach is that a high degree of scalability and real-time adaptability can be achieved. The framework is implemented on a real-time high-fidelity multi-vehicle simulator system. The effectiveness of the method is demonstrated in different scenarios for a team of airborne search vehicles looking for both a stationary and a drifting target lost at sea.

History of Doppler Radar Navigation

This paper traces the history of the development and applications of Doppler radar navigation systems from their inception in the mid-1940s to the present. The early design concepts, problems, tribulations, and obstacles are discussed. With only noncoherent pulse radar transmitters available at that time, a unique technique of self-coherence had to be invented and implemented in order to allow Doppler signal extraction. Similarly, the severe leakage problems of continuous wave (CW) radars had to be overcome. In spite of these problems, both pulse Doppler and CW Doppler radar navigation systems were successfully developed and produced. The next problem needing a solution was the measurement of negative velocity as required in helicopter operation. This lead to the development of coherent pulse and frequency modulated (FM)-CW Doppler radars and new frequency trackers, with wide application for navigation and hovering indication over land and water. The development and production of Doppler systems for the commercial airlines followed, and these systems were used for civil over-ocean navigation for many years. A Doppler radar was used for velocity measurement on the Surveyor and the Appollo Lunar Excursion Module for the achievement of soft landing on the moon. Most modern military helicopters and strategic aircraft, as well as many drones, are currently implemented with Doppler navigation radars, and this is. likely to continue. In addition, the Doppler navigation radar concepts have been applied to the so-called precision velocity update (PVU) mode of conventional military airborne search and tracking radars.

The Demand for Aviation Activities at General Aviation Airports: An Empirical Study

The Demand for Aviation Activities at General Aviation Airports: An Empirical Study

Scale model experiments on optimum transmitter-receiver configurations for resolution of electromagnetic response of multiple conductors

Electromagnetic scale modeling response curves over two parallel dykes embedded in resistive or conductive media have been obtained by using horizontal loop inline and broadside systems. It previously was established that inline configuration can electromagnetically resolve the individual conductor only when the separation between them is greater than or equal to transmitter-receiver separation. Fortunately for field geophysicists, broadside configuration can relax such a limit and resolve the two conductors even when the separation between them is half of the transmitter-receiver separation. The experimental results show that the inline configuration gives a better quantitative idea of the identity of the two resolved conductors. A combined use of these two configurations is recommended to the induction prospectors in their ground-based or airborne search for sulphide dykes. >

Radar observations of thunderstorms at Poona

Radar observations of rain have 'been made at Poona since 1953, when a small air-borne model search radar type SCR-717-C operating on 9.1 cm was set up at the Poona Observatory. The radar has a peak power of 40 KW and a pulse length of 1.125 p, s. The antenna is a dipole-fed paraboloid mounted for rotation about a horizontal axis so that the radar beam scans the sky from horizon to horizon through the zenith giving a vertical cross-section through the atmosphere above the point of observation.

The design and positioning of aircraft radar aerials for metric wavelengths

The needs of airborne search radar and navigational aids on metric wavelengths led to the development of a variety of aerial systems specially designed for fitting on aircraft. These aerial systems may be classified according to the angular coverage which they are required to provide. The most common types are all-round-looking aerials, homing aerials and search aerials.Apart from developing a suitable design of aerial an important part of the problem of providing efficient aerials on aircraft is in determining the best positions for the aerials on the aircraft. The principles of design of aircraft aerials for metric wavelengths are described and also the technique of positioning the aerials.The need for rapid switching between two or more aerials on an aircraft is common to both radar and navigational applications and the means of achieving this are briefly discussed.