1. Evaluation of the performance of a minehunting sonar - Thompson, J.L.; Bell, M.J.
The performance of mine hunting sonars fluctuates with the environment, with target characteristics and with operator skill. Because of the variability the sonar performance cannot be reliably evaluated by a single measurement but must be determined as a statistical sampling problem. The detection performance can be assessed by conducting many detection runs at various target aspects and generating probability of detection curves and confidence limits from the results. These data can then be compared to the specified performance. In practice the environmental conditions inevitably deviate from the ideal, are never as specified and usually degrade sonar performance. The influence of...

2. Evaluation of the performance of a minehunting sonar - Thompson, J.L.; Bell, M.J.
The performance of mine hunting sonars fluctuates with the environment, with target characteristics and with operator skill. Because of the variability the sonar performance cannot be reliably evaluated by a single measurement but must be determined as a statistical sampling problem. The detection performance can be assessed by conducting many detection runs at various target aspects and generating probability of detection curves and confidence limits from the results. These data can then be compared to the specified performance. In practice the environmental conditions inevitably deviate from the ideal, are never as specified and usually degrade sonar performance. The influence of...

3. Automated Detection and Classification in High-resolution Sonar Imagery for Autonomous Underwater Vehicle Operations. - Chapple, P.
Autonomous Underwater Vehicles (AUVs) are increasingly being employed for mine reconnaissance, mine hunting and hydrographic survey operations. Side-looking sonar systems can generate high-resolution seabed imagery, indicating the presence of mines and other bottom objects. Whilst human analysts may be tasked to examine the data, this approach is resource-intensive and potentially unreliable, as analysts become tired or inconsistent in their performance and are often distracted by other tasks. This document reviews the development of techniques for automated detection and classification of objects on the seabed from this imagery. These techniques have been developed to provide more reliable and consistent detection of...

4. Automated Detection and Classification in High-resolution Sonar Imagery for Autonomous Underwater Vehicle Operations. - Chapple, P.
Autonomous Underwater Vehicles (AUVs) are increasingly being employed for mine reconnaissance, mine hunting and hydrographic survey operations. Side-looking sonar systems can generate high-resolution seabed imagery, indicating the presence of mines and other bottom objects. Whilst human analysts may be tasked to examine the data, this approach is resource-intensive and potentially unreliable, as analysts become tired or inconsistent in their performance and are often distracted by other tasks. This document reviews the development of techniques for automated detection and classification of objects on the seabed from this imagery. These techniques have been developed to provide more reliable and consistent detection of...

5. ELECTROTECHNICS, ELECTRONICS, AUTOMATIC CONTROL, INFORMATICS ON ESTIMATION OF THE ORIENTATION OF MOBILE ROBOTS USING TURNING FUNCTIONS AND SONAR INFORMATION - Dorel Aiordachioaie
Abstract: SONAR systems are widely used by some artificial objects, e.g. robots, and by animals, e.g. bats, for navigation and pattern recognition. The objective of this paper is to present a solution on the estimation of the orientation in the environment of mobile robots, in the context of navigation, using the turning function approach. The results are shown to be accurate and can be used further in the design of navigation strategies of mobile robots.

6. Estimation of Noise Parameters on Sonar Images - Francoise Schmitt; Max Mignotte; Christophe Collet; Pierre Thourel
We use the Markov Random Field (MRF) model in order to segment sonar images, i.e. to localize the sea bottom areas and the projected shadow areas corresponding to objects lying on seafloor. This model requires on one hand knowledges about the statistical distributions relative to the different zones and on the other hand the estimation of the law parameters. The Kolmogorov criterion or the 2 criterion allow to estimate the distribution laws. The Estimation Maximization (EM) algorithm or the Stochastic Estimation Maximization (SEM) algorithm are used to determine the maximum likelihood estimate of the law parameters. Those algorithms are initialized...

7. Hypson 400, a real time panoramic sonar. - MONSAINGEON, L
The search for a panoramic, real-time, high frequency sonar has been a major goal for operating ranges where optical systems have established limitations. HYPSON 400 meets such requirements and provides a simultaneous and continuous beam-forming, no-scanning, wide opening system, using a hybrid beam-forming technique allowed by new component technologies. Up to seven images per second can be formed at a range of 100 meters, and more at shorter distances, as allowed by the speed of sound, thus providing the highest possible rate of information renewal required by operations at sea.

8. Broadband active sonar : implications and constraints - Lew, H.
The basic motivation for using broadband sonar is to improve the range resolution capabilities without sacrificing the detection performance, which is governed by the amount of received energy from the target. This can be achieved by increasing the bandwidth of the signals used. From this improvement in range resolution, a number of other desirable features follow such as improved range accuracy, robust parameter estimation, Doppler tolerance and so on. The report begins by examining the definition of a broadband signal. The fractional bandwidth and time-bandwidth product definitions are discussed. This naturally leads on to a discussion of broadband signal processing...

9. Broadband active sonar : implications and constraints - Lew, H.
The basic motivation for using broadband sonar is to improve the range resolution capabilities without sacrificing the detection performance, which is governed by the amount of received energy from the target. This can be achieved by increasing the bandwidth of the signals used. From this improvement in range resolution, a number of other desirable features follow such as improved range accuracy, robust parameter estimation, Doppler tolerance and so on. The report begins by examining the definition of a broadband signal. The fractional bandwidth and time-bandwidth product definitions are discussed. This naturally leads on to a discussion of broadband signal processing...

10. Advanced Sonar Sensing - Lindsay Kleeman
Robotics research is heavily dependent on fast, accurate, reliable and cheap sensors. Sonar sensing can fulfil these requirements in air and underwater environments. Moreover sonar physics provides robotics researchers with a natural selection capability for landmark detection in navigation problems. This paper presents new sonar results that allow high-speed accurate measurement and classification suitable for moving platforms that has been combined with interference rejection to allow multiple sonar systems to co-exist.

11. Performance analysis of active sonar classifiers - Haddad, Nicholas K.
This dissertation studies the theoretical underpinnings of active sonar classifiers. We present a systematic approach for designing optimal Bayesian classifiers and analyzing their performance. We emphasize the ternary case where three hypotheses are considered: H 0(noise only), H 1(reverberation plus noise) and H 2(target plus noise). We start by deriving a sufficient statistic to decide between H 1and H 2, assuming H 0has already been eliminated. Then, closed-form solutions for classification and false alarm probabilities are obtained and several receiver operating characteristics curves illustrating meaningful physical scenarios are presented. Two classes of illuminating signals are considered: high resolution and linear...

12. Suitability of Correlation Arrays and Superresolution for Minehunting Sonar - Blair, D.G.
As part of the Navy’s minehunting program, the need has been identified to acquire, if possible, improved hull-mounted sonars. These might, in particular, survey an area faster, and/or enable the detection and classification of suspected mines to occur at a greater range. Towards developing such a sonar, a project called ‘Minefinder’ has been set up. As part of Minefinder, work, reported here, has been carried out in two areas. The first area concerns arrays—to be called 'correlation arrays'—that are based on the principle used by correlation telescopes in radio astronomy. The best-known of these devices is the cross-shaped array, constructed...

13. Suitability of Correlation Arrays and Superresolution for Minehunting Sonar - Blair, D.G.
As part of the Navy’s minehunting program, the need has been identified to acquire, if possible, improved hull-mounted sonars. These might, in particular, survey an area faster, and/or enable the detection and classification of suspected mines to occur at a greater range. Towards developing such a sonar, a project called ‘Minefinder’ has been set up. As part of Minefinder, work, reported here, has been carried out in two areas. The first area concerns arrays—to be called 'correlation arrays'—that are based on the principle used by correlation telescopes in radio astronomy. The best-known of these devices is the cross-shaped array, constructed...

14. Three-Class Markovian Segmentation Of High Resolution Sonar Images - M. Mignotte; C. Collet; P. Perez; P. Bouthemy; Groupe De Traitement Du Signal
This paper presents an original method to analyze, in an unsupervised way, images supplied by a high resolution sonar. We aim at segmenting the sonar image into three kinds of regions: echo areas (due to the reflection of the acoustic wave on the object), shadow areas (corresponding to a lack of acoustic reverberation behind each object lying on the sea-bed), and sea-bottom reverberation areas. This unsupervised method estimates the parameters of noise distributions, modeled by a Weibull Probability Density Function (PDF) and the label field parameters, modeled by a Markov Random Field (MRF). As for the estimation step, we adopt...

15. The measurement of the depth of a sonar array - Collins, G.M.; Clarke, A.P.
The measurement of the depth of a sonar array using a modified counting technique for the demodulation and decoding of frequency modulated instrumentation signals is presented. A data dependent overflowing counter feeds demodulated data into a Programmable Read Only Memory based lookup table. Controlled, repeated counter overflows maximise the information content of the data. The system resolution is thus considerably increased with no effect on accuracy or component count. Frequency discriminating circuits are superfluous with this technique.

16. The effects of towfish motion on sidescan sonar images (U) - Anstee, S.D.
(U) A simulation algorithm to estimate the geometrical effects of towfish motions on sidescan sonar images is described. The results of simulations using the algorithm are discussed, and bounds for acceptable amplitudes of towfish motions are estimated. Yaw is found to be the most potentially damaging towfish motion, and a sinusoidal yaw motion with amplitude 0.5" and period 3 s is found to induce unacceptable distortion of a towfish image. The effects of towfish motions on the coverage of the seabed are also discussed.

17. The measurement of the depth of a sonar array - Collins, G.M.; Clarke, A.P.
The measurement of the depth of a sonar array using a modified counting technique for the demodulation and decoding of frequency modulated instrumentation signals is presented. A data dependent overflowing counter feeds demodulated data into a Programmable Read Only Memory based lookup table. Controlled, repeated counter overflows maximise the information content of the data. The system resolution is thus considerably increased with no effect on accuracy or component count. Frequency discriminating circuits are superfluous with this technique.

18. The effects of towfish motion on sidescan sonar images (U) - Anstee, S.D.
(U) A simulation algorithm to estimate the geometrical effects of towfish motions on sidescan sonar images is described. The results of simulations using the algorithm are discussed, and bounds for acceptable amplitudes of towfish motions are estimated. Yaw is found to be the most potentially damaging towfish motion, and a sinusoidal yaw motion with amplitude 0.5" and period 3 s is found to induce unacceptable distortion of a towfish image. The effects of towfish motions on the coverage of the seabed are also discussed.

19. Range Detection for AGV Using a Rotating Sonar Sensor - Wen-chuan Chiang; Dhyana Ch; Ra Ramamurthy; T. Nathan Mundhenk; Ernest L. Hall
A single rotating sonar element is used with a restricted angle of sweep to obtain readings to develop a range map for the unobstructed path of an autonomous guided vehicle (AGV). A Polaroid ultrasound transducer element is mounted on a micromotor with an encoder feedback. The motion of this motor is controlled using a Galil DMC 1000 motion control board. The encoder is interfaced with the DMC 1000 board using an intermediate IMC 1100 break-out board. By adjusting the parameters of the Polaroid element, it is possible to obtain range readings at known angles with respect to the center of...

20. Range Detection for AGV Using a Rotating Sonar Sensor - Wen-chuan Chiang; Dhyana Ch; Ra Ramamurthy; T. Nathan Mundhenk; Ernest L. Hall
A single rotating sonar element is used with a restricted angle of sweep to obtain readings to develop a range map for the unobstructed path of an autonomous guided vehicle (AGV). A Polaroid ultrasound transducer element is mounted on a micromotor with an encoder feedback. The motion of this motor is controlled using a Galil DMC 1000 motion control board. The encoder is interfaced with the DMC 1000 board using an intermediate IMC 1100 break-out board. By adjusting the parameters of the Polaroid element, it is possible to obtain range readings at known angles with respect to the center of...

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