Principles of Naval Weapons Systems Edited by CDR Joseph Hall, USN i Introduction In the early twentieth century, the instruments of war were simply called weapons. The cannon, the rifle, or the bayonet were all considered separate pieces of weaponry to be used in combat. By the Second World War, technology began to be integrated into combat. The invention of radar and sonar extended the field of combat to greater and greater ranges, and it was no longer necessary to sight targets directly. As technology progressed, the very nature of weapons also changed. Now, it is no longer sufficient to discuss individual pieces of weaponry, they must be taken in the context of the entire weapons system, which is the complete set of interrelating pieces that function together to achieve the goal of destroying a target. The complete description of a weapons system must include all of the means of exchanging information between sub-systems, called communication systems; all means used to locate the target, called sensors; all means used to store, launch and deliver the weapon to the target, called delivery sub-systems; and all means used to inflict damage upon the target, called destruction sub-systems. In this book, we will discuss how the various sub-systems function. The goal is to understand the principles of operation of many different weapons systems. It is expected that the reader will supplement this material with one of the many fine books describing the arsenal of weapons currently in use by the major militaries of the world. To understand how a complicated device such as a weapons system works, it is often helpful to perform some level of abstraction first. In some ways, this is also how weapons systems are designed. The abstraction is simply to ask “what are the inputs and outputs?” This question can be applied at many different levels. To illustrate this concept, consider the overall weapons system. The inputs come from the target and/or an operator. The output is the destructive force that damages the target. At the next level of abstraction, the roles of the major sub-sections can be prescribed. The sensor sub-section takes the signals from the target and outputs the location and direction of movement of the target to the delivery system. The delivery system’s output is to put the weapon in close proximity to the target. Finally, given some small separation from the weapon to the target, the destructive system outputs the destructive force to the target. Of course, most of this is obvious. However, when this method of breaking systems down into smaller functional sub-systems is applied to smaller and smaller parts, it turns out to be a very useful way to understand how complicated systems work. Once the roles of the various sub-systems are understood, then the details of its operation can be put into context. This is the approach taken here. 1 Table of Contents Chapter 1 _____________________________________________________________11 The Parameters of a Wave ___________________________________________________11 Traveling Waves ___________________________________________________________16 Frequency vs. Time Domain _________________________________________________17 Chapter 2 _____________________________________________________________21 Basic Phenomena___________________________________________________________21 Reflection ______________________________________________________________________23 Refraction ______________________________________________________________________24 Interference_____________________________________________________________________25 Diffraction______________________________________________________________________26 Antennas _________________________________________________________________ 27 The Dipole Antenna ______________________________________________________________27 Polarization_____________________________________________________________________28 Antenna Beam-forming ___________________________________________________________30 Modes of Propagation in Air _________________________________________________32 The Electromagnetic Spectrum _____________________________________________________32 Ground Waves __________________________________________________________________32 Sky Waves______________________________________________________________________33 Line of Sight ____________________________________________________________________36 Chapter 3 _____________________________________________________________39 Basic Components__________________________________________________________ 39 Transmitter _____________________________________________________________________40 The Transmission Channel_________________________________________________________40 The Receiver ____________________________________________________________________41 Modulation________________________________________________________________41 Noise_____________________________________________________________________42 Broadband (White) Noise __________________________________________________________42 Narrowband (Interference) Noise ____________________________________________________42 Chapter 4 _____________________________________________________________45 Amplitude Modulation (AM) _________________________________________________46 An AM system_____________________________________________________________ 48 The AM Spectrum__________________________________________________________49 Bandwidth______________________________________________________________________49 Efficiency ______________________________________________________________________51 2 Frequency Modulation (FM) _________________________________________________54 Bandwidth of FM __________________________________________________________55 Immunity to Static__________________________________________________________ 56 Phase Modulation (PM) _____________________________________________________56 Single Side-band (SSB)______________________________________________________ 57 Chapter 5 _____________________________________________________________61 The Binary Representation___________________________________________________62 The Binary number system_________________________________________________________62 Bits, bytes and words _____________________________________________________________64 Basic Components__________________________________________________________ 64 Central Processing Unit (CPU)______________________________________________________65 Bus ___________________________________________________________________________68 Memory________________________________________________________________________69 Input and Output (I/O) ____________________________________________________________71 Chapter 6 _____________________________________________________________73 Digital Data with Analog Signals ______________________________________________74 Amplitude Shift-Keying (ASK) _____________________________________________________74 Frequency Shift-Keying (FSK)______________________________________________________75 Phase Shift-Keying (PSK) _________________________________________________________75 M-ary Frequency/Phase Keying _____________________________________________________75 Amplitude-Phase Keying __________________________________________________________76 Capacity _______________________________________________________________________76 Minimum Shift Keying (MSK) _____________________________________________________77 Analog Data with Digital Signals ______________________________________________77 Sampling_______________________________________________________________________78 Encoding_______________________________________________________________________78 Digital - Digital ____________________________________________________________79 Parity Checksum_________________________________________________________________80 Chapter 7 _____________________________________________________________81 Multiplexing_______________________________________________________________81 Frequency Domain Multiplexing ____________________________________________________81 Time Domain Multiplexing ________________________________________________________82 Spread Spectrum Multiplexing______________________________________________________82 Local Area Networks (LAN) _________________________________________________ 83 Topology _______________________________________________________________________83 Protocols _______________________________________________________________________84 Wide Area Networks (WANs) ________________________________________________ 84 3 Fixed Wide Area Networks_________________________________________________________84 Cellular Networks________________________________________________________________85 Satellite Networks________________________________________________________________85 Chapter 8 _____________________________________________________________87 Principles of Operation______________________________________________________ 87 Mechanization _____________________________________________________________89 Radar performance _________________________________________________________95 Pulse Width_____________________________________________________________________95 Pulse Repetition Frequency (PRF) ___________________________________________________97 Radar Frequency_________________________________________________________________98 Theoretical Maximum Range Equation_________________________________________99 Chapter 9 ____________________________________________________________101 Principle of Operation______________________________________________________101 Frequency Modulated Continuous Wave (FMCW) radar _________________________104 Chapter 10 ___________________________________________________________109 Radial Velocity Discrimination_______________________________________________109 Differentiation__________________________________________________________________109 Moving Target Indicator (MTI) ____________________________________________________110 Pulse Doppler Radar_____________________________________________________________112 Limitations ____________________________________________________________________113 High Resolution Radar _____________________________________________________115 Pulse Compression ______________________________________________________________115 Synthetic Aperture Radar (SAR) ___________________________________________________116 Inverse Synthetic Aperture Radar (ISAR) ____________________________________________118 Phased Array Radar _______________________________________________________ 119 Chapter 11 ___________________________________________________________123 Radar Servo Tracking System _______________________________________________ 123 Range Tracking___________________________________________________________ 128 Track-While-Scan (TWS)___________________________________________________ 129 Phased-Array Tracking ____________________________________________________132 Tracking Networks ________________________________________________________133 Chapter 12 ___________________________________________________________135 The Electromagnetic Spectrum ______________________________________________ 135 4 Sources of Electro-Optical Radiation _________________________________________137 Thermal Radiators ______________________________________________________________137 Selective Radiators ______________________________________________________________141 Chapter 13 ___________________________________________________________145 Spreading________________________________________________________________146 Point Source ___________________________________________________________________146 Lambertian Source ______________________________________________________________147 Absorption/Scattering______________________________________________________148 Dependence of Attenuation on Wavelength __________________________________________149 Dependence of Attenuation on Range (Bouguer’s Law) _________________________________149 The Collected Flux ________________________________________________________ 151 Aperture ______________________________________________________________________151 Bandwidth Factor, F _____________________________________________________________152 Maximum Range Equation__________________________________________________ 154 Chapter 14 ___________________________________________________________157 The Field of View (FOV) ___________________________________________________157 Depth of Focus____________________________________________________________160 Scanning vs. Staring Sensors ________________________________________________ 161 Resolution _______________________________________________________________163 Spatial Resolution_______________________________________________________________163 Thermal Resolution _____________________________________________________________164 Spatial and Thermal Resolution, MRTD _____________________________________________164 Infrared Search and Tracking (IRST) Systems _________________________________166 Triangulation (passive)___________________________________________________________166 Laser range-finder (passive-active combination) _______________________________________167 Visible Band Imaging Systems ______________________________________________167 Magnification __________________________________________________________________167 Stadimeter Ranging _____________________________________________________________170 Light Amplification _____________________________________________________________171 Laser Target Illumination_________________________________________________________172 Chapter 15 ___________________________________________________________175 Acoustic Waves ___________________________________________________________176 Propagation Speed ______________________________________________________________177 Sound Pressure Level (SPL) _______________________________________________________178 Combining Sound Pressure Levels__________________________________________________179 Propagation Paths _________________________________________________________ 181 The Sound Velocity Profile (SVP) __________________________________________________181 5 Ray Tracing____________________________________________________________________184 Chapter 16 ___________________________________________________________191 Sources__________________________________________________________________191 Active Sonar ___________________________________________________________________191 Passive Sonar __________________________________________________________________192 Ambient Noise _________________________________________________________________193 Self-Noise _____________________________________________________________________196 Detection of Acoustic Energy ________________________________________________ 197 Beam-forming__________________________________________________________________197 Detection Criterion ______________________________________________________________198 Transmission Loss Formula _________________________________________________199 Range Effect ___________________________________________________________________199 Absorption/Scattering____________________________________________________________202 Other losses____________________________________________________________________203 Figure of Merit ___________________________________________________________204 Chapter 17 ___________________________________________________________209 Active Sonar _____________________________________________________________209 Transmitter ____________________________________________________________________209 Transducer Array _______________________________________________________________210 Beamforming Processor __________________________________________________________210 Duplexer ______________________________________________________________________211 Synchronizer___________________________________________________________________211 Receiver_______________________________________________________________________211 Display _______________________________________________________________________212 Passive Sonar Systems _____________________________________________________213 Hydrophone Array ______________________________________________________________213 Beamforming Processor __________________________________________________________214 Broadband Display ______________________________________________________________216 Frequency Analyzer _____________________________________________________________216 Narrowband Display_____________________________________________________________217 Variable Depth Sonar (VDS) ________________________________________________219 Towed Array Sonar Systems (TASS) _________________________________________219 Sonobuoys _______________________________________________________________221 Bistatic Sonar ____________________________________________________________ 222 Non-Acoustic Detection_____________________________________________________ 223 Visual ________________________________________________________________________223 Radar_________________________________________________________________________223 Infrared Detection_______________________________________________________________223 6 Magnetic Anomaly Detection (MAD) _______________________________________________224 Chapter 18 ___________________________________________________________225 Open and Closed Loop Systems______________________________________________ 225 The Transfer Function _____________________________________________________ 227 System Response __________________________________________________________ 229 Chapter 19 ___________________________________________________________233 Initial (Boost) Phase _______________________________________________________234 Mid-course Phase _________________________________________________________236 Terminal Phase ___________________________________________________________236 Chapter 20 ___________________________________________________________241 Global Positioning System __________________________________________________241 Principle of Operation____________________________________________________________241 System Components _____________________________________________________________244 Inertial Navigation Systems _________________________________________________ 246 Principle of Operation____________________________________________________________246 Chapter 21 ___________________________________________________________251 Interior Ballistics__________________________________________________________251 Propellant Types ________________________________________________________________252 Rifling________________________________________________________________________255 Exterior Ballistics _________________________________________________________257 Gravity _______________________________________________________________________257 Aerodynamic Forces _____________________________________________________________257 Aerodynamic Stability ___________________________________________________________258 Drift__________________________________________________________________________260 Coriolis Force __________________________________________________________________260 Aiming Errors ____________________________________________________________261 Chapter 22 ___________________________________________________________263 Explosive Reactions________________________________________________________ 263 Strength of Explosives______________________________________________________266 Categories of Explosives____________________________________________________ 268 Initiation of the Explosive Reaction ___________________________________________ 268 Chapter 23 ___________________________________________________________271 Warhead Construction _____________________________________________________ 271 7 Blast Effects______________________________________________________________272 Predicting Blast Effects_____________________________________________________ 274 Fragmentation Warheads ___________________________________________________ 276 Reduction in Velocity with Range __________________________________________________278 Chapter 24 ___________________________________________________________281 Warhead Reliability _______________________________________________________281 Probability of Kill (P k ) _____________________________________________________ 284 Circular Error Probable____________________________________________________ 285 Levels of Damage _________________________________________________________ 285 Damage Criteria for Blast Effect Warheads ____________________________________286 Damage Criteria for Fragmentation Warheads _________________________________289 Personnel______________________________________________________________________289 Aircraft _______________________________________________________________________290 Armored Vehicles_______________________________________________________________290 Probable Number of Fragments Hitting the Target _____________________________________290 Chapter 25 ___________________________________________________________293 Armor-Piercing Warheads _________________________________________________293 Explosively Formed Penetrators (EFP)_______________________________________________293 Kinetic Energy Penetrators________________________________________________________295 Fuel-Air Explosive (FAE)___________________________________________________ 296 Incendiary Warheads ______________________________________________________ 296 Chapter 26 ___________________________________________________________297 Underwater Explosions_____________________________________________________ 297 Torpedoes _______________________________________________________________299 Sea Mines________________________________________________________________301 Mine Clearing ____________________________________________________________304 Chapter 27 ___________________________________________________________307 Principles of Operation_____________________________________________________ 307 The Difference Between Fission and Fusion Reactions __________________________________308 Mechanization of a Fission Warhead __________________________________________310 The simplest warhead design: gun-type _____________________________________________311 Improvements of fission warhead design _____________________________________________312 Mechanization of a Fusion Warhead __________________________________________313 8 Nuclear Weapons Safety__________________________________________________________314 Chapter 28 ___________________________________________________________317 The Blast Wave ___________________________________________________________ 317 Thermal Pulse ____________________________________________________________320 Nuclear Radiation _________________________________________________________321 Other Effects _____________________________________________________________322 Variation in Nuclear Explosion Effects by Burst Type ___________________________ 322 Air Burst ______________________________________________________________________322 High Altitude Burst______________________________________________________________322 Surface Burst___________________________________________________________________322 Underground Burst ______________________________________________________________323 Underwater Burst _______________________________________________________________323 Nuclear Attack Defensive Measures _________________________________________323 Sequence of Events ______________________________________________________________323 Defensive Measures: Priority of Actions _____________________________________________323 Chapter 29 ___________________________________________________________325 Types of Radiation ________________________________________________________326 Gamma _______________________________________________________________________326 Neutron _______________________________________________________________________326 Beta __________________________________________________________________________327 Alpha_________________________________________________________________________327 Measuring Radiation_______________________________________________________ 328 Units of measure ________________________________________________________________329 Somatic Effects ________________________________________________________________330 Sub-Clinical Dose, 0 to 100 rem____________________________________________________331 Therapeutic Dose, 100 to 1000 rem _________________________________________________331 Palliative Dose, > 1000 rem _______________________________________________________332 Probable Health Effects resulting from Exposure to Ionizing Radiation _____________332 Protection Standards_______________________________________________________ 333 Chapter 30 ___________________________________________________________341 Damage Criterion _________________________________________________________341 Diffraction Loading _____________________________________________________________341 Drag Loading __________________________________________________________________342 Fires/Burns ____________________________________________________________________342 Radiation______________________________________________________________________343 Predicting Nuclear Blast Effects______________________________________________ 343 [...]... behavior, the angle of reflection = the angle of incidence θ I θ R Figure 2-4 Reflection 23 Chapter 2 Propagation of Waves As seen in Figure 2-4, the angles are defined as: ♦ Angle of Incidence the angle between the direction of propagation and a line perpendicular to the boundary, on the same side of the surface; and ♦ Angle of Reflection the angle between the direction of propagation of the reflected... instead of spreading out like a spherical wave Figure 2-3 Plane wave Chapter 2 Propagation of Waves 22 Electromagnetic waves propagate at the speed of light In a vacuum, the speed of propagation is about 3 x 108 m/s In other mediums, like air or glass, the speed of propagation is slower If the speed of light in a vacuum is given the symbol c, and its speed in some medium is c0, we can define the index of. .. Here’s how these numbers where obtained: ratio of 8 Hz to 32 Hz = 2.7:1.2 = 2.25:1 square root of 2.25 = 1.5:1 or 3:2 ratio of 8 Hz to 16 Hz = 2.7:0.3 = 9:1 square root of 9 = 3:1 The overall combination is therefore 3:1:2 19 Chapter 1 Waves Chapter 2 Propagation of Waves Figure 2-1 Communications satellite The process of communication involves the transmission of information from one location to another... gravity on the water offshore Basic to the process of communication is the ability to transmit or transfer information This transfer is accomplished by propagating waves of energy Therefore, to understand how communication systems work, we must first review the basics of waves The wave itself is some disturbance in a parameter that varies over its spatial dimensions The movement of the disturbance that... λ (lambda) Amplitude: the magnitude of the peak deviation from the average value of the disturbance In this case, the value of the disturbance is plotted as “y” on the vertical axis Since the wave varies about the value y=0, the amplitude is 0.5 units You can also see that this is one-half of the peak-to-peak difference The units of amplitude depend on the nature of the wave A disturbance may be a physical... related by the speed of propagation, v The wavelength now has an equivalent parameter, corresponding to the interval of time between cycles, known as the period The period is often given the symbol T A related parameter is the frequency Frequency: the number of complete cycles of a periodic wave that pass a stationary point in one second The frequency, f, is simply the inverse of the period, f = 1/T... energy, or they may be made from arrays of simple elements like dipoles In either case, where the size of the antenna is on the order of the wavelengths involved, the beamwidth can be estimated using diffraction theory Region of destructive interference θ Region of constructive interference Figure 2-11 Beams formed by two-antenna linear array 31 Chapter 2 Propagation of Waves Example: Direct Satellite TV... wave 21 Chapter 2 Propagation of Waves Figure 2-2 Spherical wave Far from its origin, the wave will have spread out far enough that it will appear have the same amplitude everywhere on the plane perpendicular to its direction of travel (in the near vicinity of the observer) This type of wave is called a plane wave A plane wave is an idealization that allows one to think of the entire wave traveling... slowly) is known as propagation The information that is to be exchanged is carried in one or more parameters of the wave The Parameters of a Wave If we were to take a “snapshot” image of a simple wave and capture its shape at a particular instant in time, we could make a plot of the value, or amplitude, of the disturbance as it varies over some distance 11 Chapter 1 Waves Value Distance 1 2 Figure 1-2 Sine... For most common mediums, as shown in Table 2-1, the index of refraction is greater than one, meaning the speed of propagation is less than in vacuum substance index of refraction vacuum air water glass 1 1.0003 1.33 1.55 Table 2-1 Indices of refraction for common substances Reflection When a plane wave encounters a change in medium, some, or all, of the wave may propagate into the new medium and some . to understand the principles of operation of many different weapons systems. It is expected that the reader will supplement this material with one of the many fine books describing the arsenal of weapons. nature of weapons also changed. Now, it is no longer sufficient to discuss individual pieces of weaponry, they must be taken in the context of the entire weapons system, which is the complete set of. to achieve the goal of destroying a target. The complete description of a weapons system must include all of the means of exchanging information between sub -systems, called communication systems; all