AiMT Volume 5 (2010), Issue 2

Self Protection of Aircraft versus Resistance of Missile Optic Seekers (CM vs. CCM)

R. Doskočil and J. Farlík

The paper deals with one of the possibilities to increase surface-to-air homing missiles optical seeker resistance against decoys (dummy targets). First, there is an introduction to contemporary aircraft countermeasures and seeker countermeasures against jamming. In the next part, a method to increase a seeker resistance with utilization of multispectral analyses of a decoys optical radiation is introduced.

Keywords: Resistance, jam, protection, optic, seeker, multispectral, analyses

Pages: 5-16

Detection Area Analysis in the ELINT System

Z. Matoušek and P. Bučka

This article proposes a comparative method of a possible analysis technique of the detection area, in the Electronic Intelligence (further ELINT) system, regarding the values of detection probability PD, false alarm probability PF and the change of output within ELINT source PZ. By this analysis it is assumed that there is a monitoring of mobile ELINT sources, which are located on the margin of ELINT system radio horizon, whereby it is necessary to carry out the radio-locating of these sources in the main lappet of directivity pattern source axis and ELINT device.

Keywords: Electronic intelligence, reconnaissance system, Doppler effect, transmitter, power agility, probability detection

Pages: 17-27

Modelling and Control of a Quadrocopter

F. Šolc

The paper describes model and development of full control of a quadrotor aerial robot. The mathematical model of quadrotor is nonlinear system based on Newton law of motion of rigid body. Control system of the quadrotor is designed with help of state variable approach and also with help of corresponding physical approach which was inspired by the former one. The quality of the model and its control is tested by simulation and on a real flying model as well.

Keywords: PQuadrocopter, quadrotor, control, flying robot, VTOL aircraft, robot

Pages: 29-38

Selection of Mode S Messages Using FPGA

P. Grecman and M. Andrle

Currently, there is a great evolution in the use of Mode S in air traffic. Simultaneously with the development of electronics, it is possible to use the FPGA (Field Programmable Gate Arrays). To address this challenge, Mode S messages selector has been designed to select Mode S questions and answers from the whole spectrum of signals captured by the receiver AOR AR 5000 A.

Keywords: DF 18, Extended squitter, FPGA, Mode S, selector, SQB, squitter, VHDL

Pages: 39-45

Methods to Increase Resistivity against Jamming in Selected Types of Optoelectronic Seekers

M. Polášek and J. Němeček

The paper deals with dilemma of the linear image field of view of the optoelectronic system which is intended for the measurement of the location of remote optical radiation sources. There is a brief description of the lay-out of the detection assemblage and conditions which have to be guaranteed to achieve the pulse position modulation which is needed to the objects detection responsive to the location. The importance of the field of view for jamming resistance and the feasibility of the field of view reduction by the electronic method is explained. This paper also deals with objects discrimination in image data using position prediction. To predict the object position in pictures sequence, principles of Kalman filtration are used. Objects discrimination is realised for matching true and predicted trajectories, when in case of their deviation the object is eliminated.

Keywords: Pulse position modulation, field of view, jamming resistance, optical radiation, object discrimination, position prediction, Kalman filtration

Pages: 45-56

Theoretical Criterion for Evaluation of the Frangibility Factor

M. Rydlo

The capability of frangible bullet to disintegrate hitting the surface of a hard target can be expressed according to the [1] by so called Frangibility Factor. At the time there are several procedures serving for evaluation of the frangibility of the frangible bullet. As far as it is known to me, all of these methods are experimental. This article deals with the theoretical criterion of the evaluation of the Frangibility Factor. This criterion is based on the evaluation of the static strength of frangible bullet and on the theoretical calculation of the limit kinetic energy of the bullet hitting the hard target of known mechanical properties.

Keywords: Frangible ammunition, frangibility, ballistics

Pages: 57-67

Effect of the Accuracy of Target Range Measurement on the Accuracy of Fire

R. Vítek and L. Jedlička

The article deals with the mutual relation between the accuracy of the target range measurement and the accuracy of fire. The stereoscopic target range measurement and its errors are briefly described in the first part. The second part of the article is focused on the impact of inaccurate target range measurement on projectile’s vertical position of the point of impact. Various ballistic systems are used for the simulation of the effect. Results of simulations are discussed from two points of view. First point of view is the use of the results for the selection of the most suitable ballistic system for the firing on the target at given range. The second one offers utilisation of the results for the setting of requirements on the accuracy of target range measurement for given ballistic system and size of the target.

Keywords: Exterior ballistics, passive range finder, target range measurement, trajectory modelling

Pages: 69-83

Omnidirectional Multi-lobe Passive Direction Finder with Modified Butler Matrix Algorithm Using

E. Hosko and J. Vesely

The article deals with an omnidirectional multi-lobe passive direction finder (PDF) that uses the modified Butler matrix operation algorithm and a digital amplitude direction finding method for the direction of arrival determination of the signal of interest. The article brings a concept of the PDF with the multi-lobe circular antenna array (CAA) for the omnidirectional interception of signals and results of the DOA determination obtained with the experimental CAA. These practical results of measuring with experimental CAA are compared with the theoretical results obtained by means of mathematical models of the PDF based on an approximation of real antenna patterns. To approximate the real antenna pattern of CAA antenna elements, an appropriate form of the Gaussian curve is used.

Keywords: Digital amplitude direction finding method, direction of arrival determination, modified Butler matrix operation algorithm, multi-lobe circular antenna array, omnidirectional direction finding

Pages: 85-100

Seismic Sensors Communication

J. Čechák

The presented paper deals with the possibilities, characteristics and useable properties of seismic-acoustic communication in the group of nodes, supplementing the information coverage of existing Unattended Ground Sensors ¦ UGS, including the selection of a suitable working frequency band for seismic communication. The conclusion of the paper generalizes the results of seismic-acoustic communication as verified in practice, and describes the advantages and disadvantages of communication channels defined in this way. In addition, the paper includes illustrative photographs of the practical design and graphic results of real measurements.

Keywords: Seismic detection, unattended ground sensor, seismic communication, remote sensing

Pages: 101-108

TECHNICAL INFORMATION
New Trends in a Vehicle Maintenance System

J. Furch

In this article the author describes particular maintenance systems used in the past, some of which are used also at present. The basic maintenance systems include maintenance after use, preventive maintenance with predetermined intervals, and conditioned-based preventive maintenance - predictive maintenance. These maintenance systems were continuously improved and new ones were added – so called computerized maintenance management system, reliability centred maintenance, and total productive maintenance. The article further describes new methods of performing the maintenance based on proactive maintenance with using telemaintenance, which may be simply explained as remote-controlled maintenance.

Keywords: Telemaintenance, maintenance, corrective maintenance, preventive maintenance, predictive maintenance, computerized maintenance management system, reliability centred maintenance, proactive maintenance

Pages: 111-119

TECHNICAL INFORMATION
Reconstruction of Armoured Bridge Layer MT-72

J. Tvarožek, P. Kacko and M. Valašiková

The paper contains constructional scheme of a vehicle and its individual aggregates, systems and subgroups. It gives constructional overview of the MT-72 vehicle. The designed conception solves re-construction shape of the vehicle hull, which makes it possible to create the compartments of driver and commander in the front of the vehicle next to each other. The transmission is also modified and adapted to enable intake of required performance for the pump drives of the vehicle’s extension. In this re-constructed bridge layer i.e. MT-72 M2 is installed new air-conditioning unit, new fire-fighting equipment by Co. DEUGRA and engine with more efficient air cleaner, too. Laying mechanism controlled by the linear hydraulic cylinder, suspensory consoles and compatibility of the bridge layer MT-72 M2 with MT-55A bridge system to simplify the user’s logistics was well-preserved.

Keywords: Bridge, bridge layer, bridge position, construction nodes, MT-72, transmission, stability

Pages: 121-136

TECHNICAL INFORMATION
Implementation of the Moodle Course Management System in English Language Training at the University of Defence

E. Staňková and H. Bušinová

The article examines the technological, methodological and systematic aspects of an e-Learning approach to English language training at the University of Defence, currently being implemented utilising the Moodle Course Management System. The article focuses on course content management in Moodle and its adaptation to the requirements of military education. The authors propose Moodle as an efficient and cost-effective technological solution for a virtual learning environment in the Armed Forces of the Czech Republic.

Keywords: ACR, Course Management System, e-Learning, English language training, Moodle, University of Defence

Pages: 137-148