Lecture_2 - EnergyFundamentals EnergyFundamentals...

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Unformatted text preview: Energy Fundamentals Energy Fundamentals Detect to Engage Sequence Detect to Engage Sequence The “Fire Control Problem” – Framework of every weapon system – “Weapon system” is a very general term – Sophisticated or simple and archaic Tomahawk vs. crew served weapons – Submarines/ships/aircraft/troops Detect to Engage Detect to Engage Detection – An alarm from Electronic Support (ES) equipment detects an electromagnetic emission on a bearing line Detect to Engage Detect to Engage Localize – A different piece of equipment, an air search RADAR, begins to pick up a return at the RADAR’s maximum range – You can now determine an accurate range and bearing Detect to Engage Detect to Engage Classify – Your ES equipment compares the emission of the contact to information stored internally and classifies the contact as a specific attack aircraft belonging to Iran Detect to Engage Detect to Engage Track – As the contact closes your position, the ships three­dimensional search and track RADAR gives you the contact’s bearing, range, course, speed, altitude – You enter the contact’s information into a common Battle Group link for all to see and continuously monitor Detect to Engage Detect to Engage Select a weapon – The contact displays a hostile act IAW current ROE by using it’s targeting RADAR on your ship, as determined by your ES equipment – A surface­to­air missile is selected Detect to Engage Detect to Engage Neutralize/Destroy – The target closes the maximum range envelope of your surface­to­air missile – Your “fire control solution” has been satisfied The weapon system is locked on and tracking the target Weapon System Requirements Weapon System Requirements Reliability Flexibility Safety Simplicity of Operation Maintainability Specific Military Requirements Three Naval Warfare Areas: Three Naval Warfare Areas: Anti­Air Warfare (AAW) Anti­Submarine Warfare (ASW/USW) Anti­Surface Warfare (ASUW/ASU) Naval Weapons Naval Weapons Systems Energy Fundamentals SA­7 Grail SA­7 Grail Energy Fundamentals Energy Fundamentals RADAR – RAdio Detection And Ranging RADAR is an electromagnetic wave that acts like any other electromagnetic wave (i.e. radio, light, etc.) Traveling Wave Characteristics Traveling Wave Characteristics Frequency Period Wavelength Amplitude Amplitude Amplitude The maximum displacement of any point on the wave from a constant reference value – It is a measure of the level of energy Frequency Frequency Period Period Wavelength Wavelength Phase Shift Phase Shift Wave Propagation Wave Propagation Reflection Refraction Diffraction Reflection Reflection When an electromagnetic wave encounters a conducting surface… Reflected and incident waves travel in directions that make equal angles with the perpendicular line from the surface – Angle of reflection and angle of incidence Reflection Reflection Phase shift = 180 degrees. Angle of incidence = Angle of reflected wave. Incident Wave Reflected Wave Reflection Reflection Reflected wave will be 180 degrees out of phase with the incident wave The only way to get reflected energy back to the source (as needed for radar to work) is to hit the material perpendicular to the surface If the surface is not flat then reflected rays will not go in the same direction (scattering) Many other things besides targets can cause reflections (dust, rain, snow, and water vapor, sandstorms in the Gulf) Refraction Refraction When a wave strikes a boundary between two transparent media in which the velocity of light differs, the incident ray will generally divide into a reflected ray and a refracted ray Snell’s Law n1 sin θ1 = n2 sin θ2 Diffraction Diffraction Causes plane waves traveling in a straight path to bend around a boundary or obstruction Diffraction Diffraction ...plane waves traveling in a straight path bend around a boundary or obstruction. detected island not detected Losses Losses Losses in energy transmission are primarily due to spreading, absorption, and scattering – Spreading: as the wave travels outward from the source, its energy is expanding over an increasingly larger area – Absorption: molecules of the medium will absorb some of the energy as the wave passes by – Scattering: results from reflections off suspended particles within a medium Maxwell’s Theory Maxwell’s Theory An accelerating electric field will generate a time­varying magnetic field A time­varying magnetic field will generate a time­varying electric field ...and so on...and so on...and so on... Maxwell’s Theory Maxwell’s Theory There is an energy transfer taking place between electrical and magnetic fields when changes occur in electrical or magnetic energy – Each affects the other… A changing electrical field produces a changing magnetic field that produces a change in the electrical field... Maxwell’s Theory Maxwell’s Theory Bottom line: – If we produce a varying electrical field we can produce a corresponding varying magnetic field – They will propagate together as electromagnetic waves ...
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  • Spring '14
  • Wavelength, Energy Fundamentals, detect

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