Echolocation Methods Roman Salamon & Henryk Lasota II 2016 – VI 2016 General information [2] authors: Roman Salamon, Henryk Lasota translated, modified, LYXed, and taught by: Henryk Lasota, Ph.D. (GUT), D.Sc. (UdV), M.Sc.E.E. (GUT) [email protected] room 748 (EA), phone: (58 347) 17 17 & 11 64 consultations: Wednesday 14:00–16:00 (& other terms by appointment) course slides & script: http://Echolocation Methods – Materials Supplementary information [3] Time dimension 30 hours, 2 lecture hours a week Acceptance requirements Written test with 60% passing threshold References (bibliography) M. Skolnik (ed.): Radar Handbook, McGraw-Hill, New York 1970, 1998, 2008 (with contributions by 30 world experts). M. Skolnik: Introduction to Radar Systems, McGraw-Hill, New York 1962, 1980, 2001. R. Salamon: Systemy hydrolokacyjne (Sonar Systems), Wyd. GTN, Gdańsk 2006. D. L. Mensa: High resolution radar cross-section imaging, Artech House, Boston 1981, 1984, 1990, 1991. R. Urick: Principles of Underwater Sound, McGraw-Hill, New York 1967, 1975, 1996. D. Martinez et al., High Performance Embedded Computing Handbook: A System Perspective, CRC Press, Boca Raton 2008 1 R. Salamon & H. Lasota 2016-06-08 Echolocation systems I Course content [4] For the purpose of the exam, the content of the course is developed in four groups: • A – I. Echolocation systems, – II, Radars and sonars, – III. Echolocation signals, Detection • B – IV, Antenna directivity, – V. Practical theory of apertures and arrays, – VI. Multibeam system techniques. • C – VII, Special purpose echolocation, – VIII. Echolocation system design • D – IX. MES Dept.- proper sonars, – X. HPEC: A systems perspective 2 R. Salamon & H. Lasota 2016-06-08 Echolocation systems I Part I Echolocation systems 1 Generalities Course philosophy – STEM [5] • STEM – mix: Remote observation and localization What, and why, do we see and hear? – Science Physical basis, technical parameters, exploitation characteristics (S -> E). – Technology Waves, their spreading - theoretical model of prop- – Engineering agation (M), practical models (S), medium inho- – Maths mogeneities, inhomogeneities in the medium. • (+Art -> STEAM ) Department of Marine Electronics Systems - sonars for the Polish Navy, echosounders for Meteorology and Water Management Authority etc. System con- Antennas (antennae) - key elements of spatial sys- ception, design (S + E + M), element design and tems (STEM manifests itself in the implementa- development (E + T), system implementation and tion process: The antenna design is an engineering tests (S + E) marine tests and exploitation in real art (E), calculations (M) are founded on the phys- sea conditions (STEM – TRL 7 / TRL 9). ical theory of diffraction (S), construction is tech- nologically complex (T). Course philosophy – Systems, waves, sygnals [6] Education =6 self-learning Electromagnetic waves (radio waves, microwaves, Lecture = reflection of an expert - experienced en- coherent light). gineer (E+T), - qualified scientist (S + M), offered Acoustic waves (sonars). to younger colleagues („greenhorns”) . Seismic waves (geophysical exploration). Acquisition of information from the environment Dedicated signal processing Radars, sonars microprocessor systems – active detection, beamforming – passive Dedicated exposition of the space and object infor- Sensor networks mation Passive acquisition systems Synchronized, asynchronous Course philosophy – Space [7] Remote interaction with objects in the environmental space: command systems, moving objects automatic control. Objects: land vehicles, aircrafts (flying units), floating on the surface, under water: car, plane, ship, submarine, autonomous vehicle (drone, UAV, USV, UUV) Information – the space itself meteorological phenomena - atmosphere underwater phenomena - hydrosphere (navigation obstacles, icebergs) tomography – sequential radio- or ultrasono-graphy: biological objects, technological elements, hy- drosphere 3 R. Salamon & H. Lasota 2016-06-08 Echolocation systems I 1.1 General working principle General working principle of echolocation system [8] Working (operation/functioning) principle The transmitter generates a powerful electric pulse. The transmit antenna radiates it into the sur- rounding space as a sounding wave – electromagnetic (radar, lidar) or acoustic (sonar, sodar) probe. The pulse wave travels through the relevant physical space (radio or sound channel) and hits a distant object (target). The reflected wave reaches (back) the receiving antenna and the electric echo signal is detected (or not) in the receiver system. The receiver detects the echo signal and measures the time τ elapsed since the moment of sending it until its reception. When the propagation speed c of the signal wave is known, the distance R of the target from the echolocation system is calculated as: cτ τ = 2R/c, meaning: R = 2 2 Basic tasks of echolocation systems Basic tasks of echolocation systems [9] Possible tasks 1. Detection of the object/target in the observed space 2. Determination of the target position – localisation 3. Estimation of selected parameters of the target 4. Target classification 5. Target identification 2.1 Target detection and localisation Target detection and localisation [10] 1. Target detection is to determine whether at a given time receiver receives the echo signal or a noise/interference. The noise occurs in the channel (space, air, water environment) and add/supperpose in the receiver to the echo signal. The determination of the presence of the useful/known signal on the noise background is called detection. 2. Target localisation relative to the echolocation system is mainly performed by measuring its distance and bearing. The latter means the angle between the direction in which the target is detected, and the reference axis. 4 R. Salamon & H. Lasota 2016-06-08 Echolocation systems I 2.2 Target bearing Target bearing [11] 2a. Target bearing can be, for example, an azimuth angle (relative to north) and elevation (relative to the earth surface). Reference system can be, eg, the plane, the ship or any device at which the echolocation system is installed. 2b. Directivity The bearing/direction measurement is performed by making use of directional properties of transmitting and receiving antennae/antennas of the echolocation system. 2.3 Estimation, classification, identification Estimation, classification, identification [12] 3. Parameter estimation consists in determining the size, velocity, direction of movement, etc. Information about these pa- rameters are sometimes included in the echo signal and can be extracted from it. 4. Target classification means the recognition in a wide (worse) or narrow (better) class of objects. For example, the detected target is a vessel (wide class) or the detected object is a boat (narrow class). 5. Target identification means an assignment to a very narrow class of objects such as a Boeing 737 or more precisely the specific aircraft (eg. “friend or foe” or “flight number...”). The course will deal with only the first three of the above mentioned tasks (excluding classification and identification) 2.4 General classification of echolocation systems General classification of echolocation systems [13] Four kinds of echolocation systems Due to the physical type of applied signal waves, echolocation systems are divided (in historical order) into: • radiolocation systems that use electromagnetic waves in air (radars), • underwater acoustic systems (hydroacoustic systems) using acoustic waves in water reservoirs (sonars), • aerolocation systems using acoustic waves in air (sodars), 5 R. Salamon & H. Lasota 2016-06-08 Echolocation systems I • geolocation systems using mechanical waves on the Earth surface and underwater, • laser systems using coherent optical waves in air (lidars). The choice of specific waves is mainly due to the size of their absorption/attenuation in the propa- gation medium. Generally, these waves are selected, that are the least attenuated in the environment of system operation. 2.5 Semantics Semantics [14] Two classes of “detection, navigation, and ranging” • radar (RAdio Detection And Ranging), • sonar (SOund Navigation And Ranging), • sodar (SOund Detection And Ranging), • lidar (LIght Detection And Ranging). Terminology (wording, nomenclature) – echolocation semantics • transmitter, • transmitting power/pulse energy, • channel/physical space, • attenuation, • object/target, • noise/interference, • receiver, • reflection/scattering, • sounding signal/sounding wave. • detection probability, • false alarm rate. General scheme of communication system [15] General scheme of echolocation system [16] 6 R. Salamon & H. Lasota 2016-06-08 Echolocation systems I Sonar transmitter - basic functionalities [17] Sonar receiver - basic functionalities [18] Echolocation devices in every day use [19] Ultrasound parking sensor Working principle: Determining the distance from the obstacle by measuring the time between the mo- ment of transmitting pulse and receiving the echo signal. Price: 4 sensors + measurer 100 zl. Ultrasonic rangefinder intellimeasure Working principle: as abowe Measuring accuracy: 0.5% Range 12 m. Price 136 zl. Echolocation devices in every day use [20] 7 R. Salamon & H. Lasota 2016-06-08 Echolocation systems I Laser rangefinder Leica Disto D210 Working principle: as in ultrasound devices, but light impulses Measuring accuracy: 1 mm Range 80 m. Price 350 zl. One of the MES Dept. sonars - a poster [21] MG-89DSP, imaging, parameters, scheme [22] One of the MES Dept. sonars -