Principles of Naval Weapons Systems Edited by CDR Joseph Hall

Principles of Naval Weapons Systems Edited by CDR Joseph Hall, USN 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. i 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 1 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 2 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 3 ... - 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