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1
Content available Optimizing of target detection and tracking processes realized on consoles of passive sonar with linear towed antenna
Raganowicz A., Sadowski K., Dolot M., Kilian L.
Hydroacoustics
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2016
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Vol. 19
329--334
EN
The long-range passive towed sonar was first modernised a few years ago. Building on operator experience over that period, a concept was developed of optimising the tasks performed by sonar operators, and improving forms of imaging to inform about object detection and support object tracking. The concept was implemented and successfully tested during ships’ manoeuvres. The optimisation of operator tasks was designed to keep listening for signals from an object separate from object tracking. Operator tasks have been made easier by rearranging the imaging, improving interaction between monitors, extending the navigation imagery module, adding new tools for building an acoustic database of potential targets; and improving the recording, browsing and playback of key recorded data. The article gives a more detailed account of the project and its results.
2
Content available Application of maximum length sequence in silent sonar
Marszal J., Salamon R., Kilian L.
Hydroacoustics
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2012
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Vol. 15
143-152
EN
Silent sonars are designed to reduce the distance over which their sounding pulses can be detected by intercept sonars. In order to meet this objective, we can use periodical sounding signals that have low power, a very long duration and wide spectrum. If used in the silent sonar’s receiver, matched filtration ensures very good detection of motionless or slow moving targets. However, it is more difficult to detect echo signals of fast moving targets with Doppler effect causing significant error in target distance measurements. In an effort to find signals that can better resist Doppler effect, maximum length sequence was tested for its application in silent sonar. It has an elementary signal which includes linear frequency modulation. It was demonstrated that the signal produces much better results than those obtained with simple frequency modulation signals.
3
Content available Visualisation forms in MCM side scan sonar
Kilian L., Raganowicz A., Sidorko T.
Hydroacoustics
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2010
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Vol. 13
119-126
EN
The article discusses forms of visualisation on the monitors of an MCM side scan sonar with towbody modernised by the DMES. The introduction gives an overview of the structure of the sonar, how it collects signals and the nature of the signals. This forms the basis for how the signals are visualised. Next a description is given of other factors which determine the form of visualisation on the sonar’s monitors. They are the operator’s tasks and the display of the settings, the readings of additional sonar sensors, how the system cooperates with other onboard systems, operator training and ergonomics. Examples of visualisation are included.
4
Content available Modernization of ASW sonar SQS-56 at Gdansk University of Technology
Marszal J., Schmidt J., Salamon R., Kilian L., Raganowicz A., Zachariasz K., Ostrowski Z., Jedel A., Rudnicki M., Sidorko T.
Hydroacoustics
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2010
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Vol. 13
191-196
EN
The fast development of electronic technology and digital signal processing methods makes electronic devices, including sonar systems ones, obsolete very quickly. On the other hand the ships mechanical components including mechanical parts of sonars are operational for a few dozens of years. It makes good opportunity to modernize these devices by using modern electronic devices and new digital signal processing methods with application of existing antenna and mechanical systems. The paper presents the modernization of ASW sonar SQS-56 on the Polish frigate ORP “Kościusko”. The aim of modernization, the new parameters of the sonar and block diagram after modernization are presented.
5
Content available Workstation for training ASW helicopter navigators and analysing real flight data
Raganowicz A., Kilian L., Marszal J., Schmidt A., Sidorko T., Rudnicki M.
Hydroacoustics
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2009
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Vol. 12
181-188
EN
The article presents a training and diagnostic workstation designed for Polish Navy ASW helicopter navigators. Installed at the helicopter base, the workstation is used for training and instruction in operating the device and analysing information gathered by navigators during the flight using the ASW onboard sonar, sonobuoy receiver and magnetometer. The workstation allows instructors to task two operators and monitor their performance under conditions resembling those onboard a plane. The tasks involve the operation of the consoles and collecting information during tactical situations, diagnosing damage and analysing flight data in office environment. The objective is to ensure proper helicopter navigator training and experience given the limited possibility of training flights.
6
Content available Time variable gain for long range sonar with chirp sounding signal
Marszal J., Ostrowski Z., Schmidt J., Kilian L., Jedel A., Schmidt A.
Hydroacoustics
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2007
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Vol. 10
117-122
EN
The main purpose of applying Time Variable Gain (TVG) in active sonars with digital signal processing is to reduce dynamic range of echo signal and adapt it to the dynamic range of the analogue to digital conversion. With high transmission losses level, the dynamic range of the input signal in long range sonars can be very high and even exceed 200 dB. When chirp sounding signals with matched filtration are used, sonars can reach very long ranges. The article presents optimisation of TVG control for long range sonars. It also looks at the influence of chirp sounding signal compression, the result of digital matched filtration, for the TVG controlling. The examples of obtained results are presented.
7
Content available Research and development on underwater acoustic systems at Polish Naval Academy and Gdansk University of Technology for the Polish Navy
Grelowska G., Kilian L.
Hydroacoustics
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2006
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Vol. 9
65-70
EN
The article begins with an overview of how the Universities and the Polish Navy have benefited from what has been nearly fifty years of cooperation. The article goes on to discuss the last decade’s hydroacoustics projects for the Navy. The Naval Academy’s contribution involves measurements and analyses of ships’ hydroacoustic fields including the technical applications of the projects as well as the application of propagation non-linear effects of acoustic waves in water. The University of Technology’s primary contribution has been the modernisation of the Polish Navy’s underwater acoustic systems.
8
Content available Dynamic control of the receiving beam horizontal cross-section in the side scan sonar
Jedel A., Kilian L., Marszal J., Ostrowski Z., Salamon R.
Hydroacoustics
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2005
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Vol. 8
69-76
EN
A decade old side scan sonars are now being modernised by way of dynamically controlling the width of the receiving beam in the horizontal cross-section. The result is a quasi-constant linear resolution of the sonar (replacing constant angular resolution), when it picks up echo signals as it moves further away from the targets. The advantage of the treatment is that the ship using the side scan sonar can increase its speed without risking the loss of near targets’ echo. The articles describes how the system of dynamic control was implemented. Special TVG systems were introduced to control dynamic signal gain from several separate sections of the sonar’s acoustic array, which was divided symmetrically into unequal sections. The location of these systems in the sonar’s receiver is presented. Examples are given of curves that control TVG and of the effects of dynamic horizontal stabilisation of the sonar’s linear resolution as it receives signals.
9
Content available Hydrographic echosounder for sounding inland waters
Jedel A., Kilian L., Marszal J., Ostrowski Z., Wojan Z., Zachariasz K.
Hydroacoustics
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2004
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Vol. 7
89-96
EN
This article describes a new echosounder model designed specifically for institutions responsible for the management of inland waterways, artificial and natural reservoirs, and marine coastal waters. The basic requirement related to the need of sounding shallow waters is measuring the smallest possible depths. Using separate transducers (sending and receiving) and attenuating them, and introducing a high dynamic range TVG circuit allowed the measurement of depths from 20cm at a maximum range of 100m. Water temperature is measured in order to include sound velocity corrections. The echosounder is manufactured using modern technology, with a PC 104 computer, robust FLASH memory emulating a hard disk, 8 inch color LCD panel, thermal printer with paper band for instant profile printouts, and a floppy disk drive for permanent storage. The echosounder interfaces to GPS.
10
Content available Principles of computing and displaying the results of detection by underwater systems as part of sound velocity measurements
Raganowicz A., Kilian L., Salamon R.
Hydroacoustics
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2003
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Vol. 6
267--274
EN
The paper presents the upgraded system for measurements of sound velocity profiles and for computing and imaging the terms of detection in different hydrolocation and hydrocommunication systems. Three types of computations made by the system's processors are discussed. The most interesting task is to link the propagation routes and ray density with the parameters of the hydroacoustic system to obtain the desired display of the conditions to detect the signal from the background noises. Presented discussion of methodology of determining detection conditions using different forms of range equation gives a more detailed description of this task. In the next part of this paper the software's display function and necessary settings are specified and discussed. In the end two examples of computed detection conditions images (for active and passive sonar) are shown.
11
Content available Autonomous hydroacoustic sound velocity profiler
Jedel A., Marszal J., Ostrowski Z., Kilian L.
Hydroacoustics
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2003
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Vol. 6
261--266
EN
The paper presents the autonomous hydroacoustic sound velocity profiler collaborating with ordinary PC by small box included interface & battery charger. The measurement and calibration methods and block diagram of the meter are presented as well as principles of operation, data collection, selection and transmission. There are described three versions of this meter - dropped from "normal" ships, installed in the light hull of submarines and casings in the hulls of variable depth sonar antennas.
12
Content available Special forms of echo visual representation in an ahead looking sonar
Raganowicz A., Kilian L., Ostrowski Z.
Hydroacoustics
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2002
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Vol. 5
47--52
EN
The paper discusses ways to organise visual representation in a multi-beam ahead looking sonars whose function is to detect objects on the bottom and in pelagic zones. Forms of visual representation are shown and illustrated on the basic screen (panoramic representation and setting, alarms) and on the auxiliary screen (type A, B and special). Special forms of visual representation are mainly used in detecting objects in difficult hydrological conditions and when classifying objects. Several types of visual representations are shown, including a historical data example, multiplied type A representation in multiple beams and two types of quasi-spatial displays.
13
Content available Optimising acoustic field intensity algorithms using the sound ray surface density method
Raganowicz A., Gawrysiak J., Salamon R., Kilian L.
Hydroacoustics
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2002
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Vol. 5
41--46
EN
The paper presents ways to optimise computer algorithms for the calculation of acoustic field intensity distribution in a body of water for specific hydrological conditions while aiming to reduce the computation time. Examples are given including an algorithm that minimises the number of range section zones. Other examples include ways to eliminate some of the time-consuming activities by determining parabola sectors instead of circular sectors as fragments of range profiles. The consequences, i.e. the possibility of varying results, are discussed. Other optimising possibilities are explored, as well.
14
Hydroakustyczny system transmisji danych w wodach płytkich z zastosowaniem modulacji MFSK
Schmidt J., Zachariasz K., Salamon R., Kilian L.
Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje
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2001
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Vol. 83, nr 27
289-292
EN
The paper presents a hydroacoustic system for the transmission of digital data in shallow coastal waters of which multi-path propagation and intense reverberations are characteristic. To ensure a small error probability of moderate speed transmission, the system uses Corrective Hamming's codes and a technique of incoherent modulation MFSK (Multi Frequency Shift Keying). To synthesise the transmission signal, estimate the spectrum of the signal received and code and decode the channels, a DSP processors are used. The paper includes the results of a simulation in which the system was put to work in the presence of Gaussian noise. The system was tested in shallow lake waters and the first results are discussed in the paper.
15
Content available Visual representation of the effects of spatial and frequency filters applied in passive sonars
Raganowicz A., Salamon R., Rudnicki M., Kilian L.
Hydroacoustics
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2001
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Vol. 4
213--116
EN
The operator of a passive sonar should be able to discern the direction (bearing) of a submerged, noise-producing object. Interference to bearing comes from reverberations, noise from the sea, man-made noise and noise generated by other objects. The article presents methods of spatial and frequency filtration designed to provide various forms of display of those fragments of the spectrum that are of interest to the operator. The operator makes his selection on the basis of many spectrograms that are produced during the successive listening cycles, displayed on the monitor. The amplitudes of spectral lines in the spectrograms are presented as lines of various lengths and colours. The summation spectrum of the displayed listening cycles is presented, too. The lines from a selected spectral range are shown on the panoramic amplitude graph in the function of the bearing angle. Thanks to that the determination of the location of the source of sound is significantly improved. The source of sound can also be discerned by using a reverse technique whereby a group of spectral lines is determined on the basis of a selected sector of angular observation.
16
Content available Symulacja sygnałów i zakłóceń hydrokustycznych w komputerowych trenażerach sonarów
Raganowicz A., Kilian L.
Hydroacoustics
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2000
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Vol. 3
141--146
EN
In training simulators of older sonars, made in analog technology, noise, reverberation and echo signals were generated and processed by complicated, analog circuits informs close to real signals. In simulators of new sonar's generation, with computer processing and displaying, the generation of dynamic sonar images, included full signal processing realized by real sonar, is possible directly by personal computer. In this paper some methods of echo signals, reverberations, and noise computer generation for made training simulator of ahead and side looking sonars are presented as well, as changes of sonar's settings simulation and some regards about construction of simulators and simple communication with computer "teacher's" station. Two examples of real and simulated displays (for ahead and side looking sonars) are shown.
17
Content available New signal processing in a passive sonar with gradient antenna
Salamon R., Marszal J., Kilian L., Jedel A.
Hydroacoustics
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2000
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Vol. 3
129--134
EN
The well-known set up of an acoustic source bearing consists of four ultrasonic transducers located in the corners of a square and an additional fifth transducer placed in the centre of the square. The subtractions of the signals from the opposite transducers are proportional to sine and cosine of the angle of the arrival wave. The subtracted signals are modulated by the signal from the central transducer and treated as co-ordinates (X, Y) of the points exposed on the display with the Cartesian co-ordinate system. However such a simple solution has one serious limitation, viz., it gives satisfactory results only when a signal to noise ratio is high enough, because the noise frequency band is large compare with the bandwidth of measured signal. The paper presents an improved version of the system. Received signals are sampled and their discrete Fourier transforms are calculated. Every spectral line in DFT is presented as an individual point on the monitor. The angular position of the point shows the direction of the wave arrival and the distance from the co-ordinate origin is proportional to the power of the spectral line.
18
Content available Multibeam sonar with hexagonal array
Salamon R., Marszal J., Kilian L., Jedel A., Ostrowski Z., Raganowicz A., Rudnicki M., Wofan Z., Zachariasz K.
Hydroacoustics
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1999
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Vol. 2
133--138
EN
The paper presents a multi-beam digital sonar that was designed for monitoring and fish stock assessment in in/and waters. The sonar can also be used as a bottom profiler in lakes, rivers and shallow sea areas. The hexagonal piezoelectric transducer array co-operates with a commutator set. The 32 -channel digital beamformer creates 30 narrow receiving beams in every 60o sector of simultaneous observation. The six sectors cover the whole 360o angle range of the sonar. The beamformer digital signal processing is based on second order sampling of echo signals and the phase-shifting principle of beam deflection. The sonar block diagram, beamformer algorithms, as well as transducers designs are discussed.
19
Content available Signal processing in the hydroacoustic ships berthing aid system
Marszal J., Salamon R., Kilian L., Raganowicz A., Szurowski T.
Hydroacoustics
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1997
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Vol. 1
237--242
EN
The berthing of ships is an extremely complicated task that requires decisions on the movement of ships based on a large number of variabies: tide wind, visibility, speed, distance from jetty. Particular difficulties are related to the less maneuverable ships such as very large crude carriers. The presented hydroacoustic ships berthing aid system measures four distances of a ship to the jetty using the sonar echo method. The system computer calculates the bow and stern speed and distances to dolphins from the measured data. The results obtained are simultaneously presented on a large, high luminance display as well as printed out and recorded on computer discs. Additionally the dolphins displacements are measured and the data obtained together with its statistical parameters are recorded.
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