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Acoustic Homing
Acoustic homing is a system which uses the acoustic signature (sound) of a target to guide a moving object, such as a torpedo. Acoustic homing can be either passive or active in nature. Using passive homing, the system is designed to move either toward or away from a sound, and may also be designed to move only toward certain types of sounds to the exclusion of others, while active homing makes use of active sonar. The system emits a sound pulse that reflects off objects and then back to the system, where the system processes the echos to determine the proper response. Method An object can be equipped with two or more acoustic transducers, which function as speakers and microphones. If a transducer receives a sound louder than that received by the other transducer, the object turns in the transducer's direction. If the object is to manoeuvre in three-dimensional space, more than two transducers are needed. Typically, more than three transducers are used, and arrays of over 100 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustic Signature
The term acoustic signature is used to describe a combination of acoustic emissions of sound emitters, such as those of ships and submarines. In addition, aircraft, machinery, and living animals can be described as having their own characteristic acoustic signatures or sound attributes, which can be used to study their condition, behavior, and physical location. Military use The analysis of acoustic signatures is an important adjunct to passive sonar used to track naval warships and weapons. Similar methods have been used to identify aircraft, especially before the development of sophisticated radar tracking. Sound characteristics The acoustic signature is made up of a number of individual elements. These include: *Machinery noise: noise generated by a ship's engines, propeller shafts, fuel pumps, air conditioning systems, etc. *Cavitation noise: noise generated by the creation of gas bubbles by the turning of a ship's propellers. *Hydrodynamic noise: noise generated by the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges. Acoustics Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration, sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an ''acoustician'', while someone working in the field of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torpedo
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such a device was called an automotive, automobile, locomotive, or fish torpedo; colloquially a ''fish''. The term ''torpedo'' originally applied to a variety of devices, most of which would today be called mines. From about 1900, ''torpedo'' has been used strictly to designate a self-propelled underwater explosive device. While the 19th-century battleship had evolved primarily with a view to engagements between armored warships with large-caliber guns, the invention and refinement of torpedoes from the 1860s onwards allowed small torpedo boats and other lighter surface vessels, submarines/ submersibles, even improvised fishing boats or frogmen, and later light aircraft, to destroy large ships without the need of large guns, though ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: ''passive'' sonar means listening for the sound made by vessels; ''active'' sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic) to extr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transducers
A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.). The process of converting one form of energy to another is known as transduction. Types * Mechanical transducers, so-called as they convert physical quantities into mechanical outputs or vice versa; * Electrical transducers however convert physical quantities into electrical outputs or signals. Examples of these are: ** a thermocouple that changes temperature differences into a small voltage; ** a linear variable differential transformer (LVDT), used to measure displacement (position) changes by means of electrical signals. Sensors, actuators and transceivers Transducers can be categorized by wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loudspeaker
A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or "loudspeaker", comprises one or more such speaker ''drivers'', an enclosure, and electrical connections possibly including a crossover network. The speaker driver can be viewed as a linear motor attached to a diaphragm which couples that motor's movement to motion of air, that is, sound. An audio signal, typically from a microphone, recording, or radio broadcast, is amplified electronically to a power level capable of driving that motor in order to reproduce the sound corresponding to the original unamplified electronic signal. This is thus the opposite function to the microphone; indeed the ''dynamic speaker'' driver, by far the most common type, is a linear motor in the same basic configuration as the dynamic microphone which uses suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microphones
A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production, live and recorded audio engineering, sound recording, two-way radios, megaphones, and radio and television broadcasting. They are also used in computers for recording voice, speech recognition, Voice over IP, VoIP, and for other purposes such as ultrasonic sensors or Automatic Performance Control, knock sensors. Several types of microphone are used today, which employ different methods to convert the air pressure variations of a sound wave to an electrical signal. The most common are the dynamic microphone, which uses a coil of wire suspended in a magnetic field; the condenser microphone, which uses the vibrating Diaphragm (acoustics), diaphragm as a capacitor plate; and the contact microphone, which us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weapons
A weapon, arm or armament is any implement or device that can be used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime, law enforcement, self-defense, warfare, or suicide. In broader context, weapons may be construed to include anything used to gain a tactical, strategic, material or mental advantage over an adversary or enemy target. While ordinary objects – sticks, rocks, bottles, chairs, vehicles – can be used as weapons, many objects are expressly designed for the purpose; these range from simple implements such as clubs, axes and swords, to complicated modern firearms, tanks, intercontinental ballistic missiles, biological weapons, and cyberweapons. Something that has been re-purposed, converted, or enhanced to become a weapon of war is termed weaponized, such as a weaponized virus or weaponized laser. History The use of weapons is a major driver of cult ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torpedos Axb01
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such a device was called an automotive, automobile, locomotive, or fish torpedo; colloquially a ''fish''. The term ''torpedo'' originally applied to a variety of devices, most of which would today be called mines. From about 1900, ''torpedo'' has been used strictly to designate a self-propelled underwater explosive device. While the 19th-century battleship had evolved primarily with a view to engagements between armored warships with large-caliber guns, the invention and refinement of torpedoes from the 1860s onwards allowed small torpedo boats and other lighter surface vessels, submarines/ submersibles, even improvised fishing boats or frogmen, and later light aircraft, to destroy large ships without the need of large guns, though ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustic Quieting
Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching the observer. Machinery vibrates, causing sound waves in air, hydroacoustic waves in water, and mechanical stresses in solid matter. Quieting is achieved by absorbing the vibrational energy or minimizing the source of the vibration. It may also be redirected away from the observer. One of the major reasons for the development of acoustic quieting techniques was for making submarines difficult to detect by sonar. This military goal of the mid- and late-twentieth century allowed the technology to be adapted to many industries and products, such as computers (e.g. hard drive technology), automobiles (e.g. motor mounts), and even sporting goods (e.g. golf clubs). Aspects of acoustic quieting When the goal is acoustic quieting, a number of different aspects might be considered. Each aspect of acoustics can be taken alone or in concert so that the end result is that the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guidance System
A guidance system is a virtual or physical device, or a group of devices implementing a controlling the movement of a ship, aircraft, missile, rocket, satellite, or any other moving object. Guidance is the process of calculating the changes in position, velocity, altitude, and/or rotation rates of a moving object required to follow a certain trajectory and/or altitude profile based on information about the object's state of motion. A guidance system is usually part of a Guidance, navigation and control system, whereas navigation refers to the systems necessary to calculate the current position and orientation based on sensor data like those from compasses, GPS receivers, Loran-C, star trackers, inertial measurement units, altimeters, etc. The output of the navigation system, the navigation solution, is an input for the guidance system, among others like the environmental conditions (wind, water, temperature, etc.) and the vehicle's characteristics (i.e. mass, control system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
