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2003

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Articles 1171 - 1200 of 2071

Full-Text Articles in Engineering

Evaluating The Performance Of Multiple Classifier Systems: A Matrix Algebra Representation Of Boolean Fusion Rules, Justin M. Hill Mar 2003

Evaluating The Performance Of Multiple Classifier Systems: A Matrix Algebra Representation Of Boolean Fusion Rules, Justin M. Hill

Theses and Dissertations

Given a finite collection of classifiers one might wish to combine, or fuse, the classifiers in hopes that the multiple classifier system (MCS) will perform better than the individuals. One method of fusing classifiers is to combine their final decision using Boolean rules (e.g., a logical OR, AND, or a majority vote of the classifiers in the system). An established method for evaluating a classifier is measuring some aspect of its Receiver Operating Characteristic (ROC) curve, which graphs the trade-off between the conditional probabilities of detection and false alarm. This work presents a unique method of estimating the performance of …

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Combining And Analyzing The Tanker And Aircrew Scheduling Heuristics, Cem Boke Mar 2003

Combining And Analyzing The Tanker And Aircrew Scheduling Heuristics, Cem Boke

Theses and Dissertations

Air refueling is an integral part of U.S. air power across a wide range of military operations. It is an essential capability in the conduct of air operations worldwide and is especially important when overseas basing is limited or not available. The planning, tasking, and scheduling of aerial refueling require solution of two major problems: assigning and scheduling of tankers to refueling points and efficiently assigning crews to each tanker. To address the scheduling of tankers, Wiley (2001) developed an efficient tabu search approach. Combs (2002) developed another tabu search approach to assign crews to tankers. This research combines the …

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Search Theory And U-Boats In The Bay Of Biscay, Ronald Gregory Carl Mar 2003

Search Theory And U-Boats In The Bay Of Biscay, Ronald Gregory Carl

Theses and Dissertations

Threats to our nation's resources and forces are becoming increasingly lethal and mobile. Therefore, our ability to locate and interdict these threats is more important than ever. Search theory is one tool that is vital to countering the increasing threat. This research presents a multi-agent simulation, built around the Allied search for U-boats in the Bay of Biscay during World War II, which extends several classic search theory algorithms. Comparison of techniques is based on the effectiveness of finding high- valued, mobile assets. A JAVA-based multi-agent simulation model is designed, built and tested, and used to demonstrate the existence of …

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Calculation Of The Actual Cost Of Engine Maintenance, Oguz Ezik Mar 2003

Calculation Of The Actual Cost Of Engine Maintenance, Oguz Ezik

Theses and Dissertations

The cost of military operations has been difficult to determine, yet considered of high importance. The cost of an operation is largely dependent upon the answers to subordinate questions involving the discrete costs of military activities, like supporting individual items, While different cost estimates have received attention from the media, the question arises as to how accurate these figures are, There have been numerous studies performed by the Operations Research analysts to minimize costs while allocating scarce resources, However, the values of these studies are dependent upon whether or not the cost figures used are sufficiently "true" or accurate, This …

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Optimum Component Design In N-Stange Series Systems To Maximize The Reliability Under Budget Constraint, Huseyin Gozebe Mar 2003

Optimum Component Design In N-Stange Series Systems To Maximize The Reliability Under Budget Constraint, Huseyin Gozebe

Theses and Dissertations

This research is intended to find a new heuristic for solving the reliability optimization of n-stage series system. The new heuristic will make the initial system design and use redundancy to improve system reliability level. The limited capacity of common optimization tools requires the new heuristic to be coded in VBA programming language. Moreover, the known reliability optimization heuristic, marginal analysis will be coded so that the difference between two heuristics can be seen and design engineers can use the best result in their applications.

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Analysis Of Scheduling Policies For A M/G/I Queue With Rework, Jennifer Hendrixson Mar 2003

Analysis Of Scheduling Policies For A M/G/I Queue With Rework, Jennifer Hendrixson

Theses and Dissertations

This thesis analyzes a multi-class M/G/1 priority queueing system in which distinct job types require one service cycle and, with non-zero probability, require a second service cycle. The main objective is to find a new heuristic scheduling policy that minimizes the long-run expected holding and preemption costs. Arrival rates, service rates, and the probability of undertaking second service are all class specific. A mean value analysis (MVA) approach was employed to derive the long- run mean time in queue for each job type under each policy, thereby providing the appropriate cost equations. Numerical experiments suggest that the preemptive resume scheduling …

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Planning Coverage Of Points Of Interest Via Multiple Imaging Surveillance Assets: A Multi-Model Approach, Sarah E. Jackson Mar 2003

Planning Coverage Of Points Of Interest Via Multiple Imaging Surveillance Assets: A Multi-Model Approach, Sarah E. Jackson

Theses and Dissertations

For the United States to maintain information superiority, it is necessary to have a means of allocating intelligence-gathering assets to collect information on particular points of interest. In today's geopolitical environment, however, the number of points of interest is growing rapidly, whereas the number of available assets is not. To aid in maintaining information superiority, this research explores the use of a Multi-Modal Goal Programming Resource Constrained Project Scheduling approach for allocating imaging surveillance assets (land, air, sea, and space) to a set of points of interest for a given time period. The multiple objectives of this formulation are to …

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A Value Focused Thinking Approach To Software Interface In A Complex Analytical Domain, Christopher M. Mcgee Mar 2003

A Value Focused Thinking Approach To Software Interface In A Complex Analytical Domain, Christopher M. Mcgee

Theses and Dissertations

The intelligence community is faced with an extensive amount of data. Software programs are being developed to examine this issue of data overload and to develop solutions. The responsibility of making the final software decision lies on the analyst, therefore, the interface is the key to linking the intelligence data to the processing and results, If the interface is difficult and complex, the software will be less likely to be used. A methodology must be created which can objectively evaluate the effectiveness of the interface, This methodology will also measure the improvements in the interface's effectiveness that result when various …

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Modeling Homeland Security: A Value Focused Thinking Approach, Kristopher A. Pruitt Mar 2003

Modeling Homeland Security: A Value Focused Thinking Approach, Kristopher A. Pruitt

Theses and Dissertations

The events of September 11, 2001 have propelled the topic of homeland security to the forefront of national concern. The threat of terrorism within the United States has reached an unprecedented level. The pervasive vulnerabilities of the nation's critical infrastructure coupled with the destructive capabilities and deadly intentions of modern terrorists pose extraordinary risks. The United States must mitigate these risks while at the same time balancing the associated costs and impact on civil liberties. Currently, the United States lacks effective methods and measure for assessing the security of the homeland from acts of terrorism. This study outlines a first …

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Analysis Of Cooperative Behavior For Autonomous Wide Area Search Munitions, Orhan Gozaydin Mar 2003

Analysis Of Cooperative Behavior For Autonomous Wide Area Search Munitions, Orhan Gozaydin

Theses and Dissertations

This research investigates the effectiveness of autonomous wide area search munitions using cooperative and non-cooperative behavior algorithms under various scenarios. The scenarios involve multiple autonomous munitions searching for an unknown number of targets with different priorities at unknown locations. For the cooperative cases, communications are allowed between the munitions to help locate, identify, and decide to pursue an attack on a target or to continue searching the rest of the battlefield. For non cooperative cases, munitions independently search, detect, identify and decide to attack an identified target or continue to search. Performance of the cooperative munitions depends on numerous parameters …

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Reduction Of Thermal Residual Strains In Adhesively Bonded Composite Repairs, Heather R. Crooks Mar 2003

Reduction Of Thermal Residual Strains In Adhesively Bonded Composite Repairs, Heather R. Crooks

Theses and Dissertations

Many military and commercial aircraft are being called upon to fly well beyond their original intended service lives. This has forced the United States Air Force (USAF) to increasingly rely on structural repairs to address fatigue induced damage and to extend aircraft useful life. The focus of this research is the use of a high-strength composite patch technique to repair a fatigue crack on an aluminum aircraft structure. This study investigates the thermal residual strains that occur as a direct result of the coefficient of thermal expansion (CTE) mismatch between the repair patch and the underlying cracked metallic structure to …

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The Effect Of A Hard Coating On The Damping And Fatigue Life Of Titanium, Frank T. Ivancic Mar 2003

The Effect Of A Hard Coating On The Damping And Fatigue Life Of Titanium, Frank T. Ivancic

Theses and Dissertations

This project compares the damping and fatigue life of bare titanium plates to those coated with magnesium aluminate spinel (mag spinel). Two different coating thicknesses were tested: .005" per side and .010" per side (total thicknesses of .010" and .020"). Dynamic ping tests were conducted on all specimens to determine their resonance frequencies. Laser vibrometry was used to determine the mode at each resonance frequency. Damping ratios were determined through the use of sine sweeps. A vibration mode was selected at which to fatigue the specimens, and the stress pattern was analyzed utilizing the Stress Pattern Analysis by Thermal Emissions …

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Computational Fluid Dynamics Investigation Of Vortex Breakdown For A Delta Wing At High Angle Of Attack, Jacob A. Freeman Mar 2003

Computational Fluid Dynamics Investigation Of Vortex Breakdown For A Delta Wing At High Angle Of Attack, Jacob A. Freeman

Theses and Dissertations

Using the commercially available FLUENT 3-D flow field solver, this research effort investigated vortex breakdown over a delta wing at high angle of attack (α) in preparation for investigation of active control of vortex breakdown using steady, along- core blowing. A flat delta-shaped half-wing with sharp leading edge and sweep angle of 60° was modeled at α=18° in a wind tunnel at Mach 0.04 and Reynolds number of 3.4 x 105. A hybrid (combination of structured and unstructured) numerical mesh was generated to accommodate blowing ports on the wing surface. Results for cases without and with along-core blowing …

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A Comparison Of Nonlinear Algorithms To Prevent Pilot-Induced Oscillations Caused By Actuator Rate Limiting, James G. Hanley Mar 2003

A Comparison Of Nonlinear Algorithms To Prevent Pilot-Induced Oscillations Caused By Actuator Rate Limiting, James G. Hanley

Theses and Dissertations

The objective of this study was to compare the ability of the Feedback-with-Bypass (FWB) and the Derivative-Switching (DS) flight control system filters to prevent PIO during actuator rate limiting, and the filters' effects on aircraft handling qualities. This comparison was conducted in three steps: computer simulation, ground simulation in the Large Amplitude Multimode Aerospace Research Simulator (LAMARS), and flight tests conducted in the Variable Stability In-flight Simulator Test Aircraft (VISTA). During computer simulation, the FWB filter better reduced the phase lag and prevented sustained or divergent oscillations during the closed-loop analysis. During both ground simulation and flight tests, the FWB …

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Structurally Integrated Antennas On A Joined-Wing Aircraft, Ben P. Smallwood Mar 2003

Structurally Integrated Antennas On A Joined-Wing Aircraft, Ben P. Smallwood

Theses and Dissertations

This research is a foundational study of conformal, load-bearing antenna arrays embedded into the wing structure of a joined-wing aircraft. It is a multidisciplinary effort that touches on the aerodynamic structural and electromagnetic design considerations that stem from this unique type of sensor integration. The antenna performance Finite Element Model (FEM) and control surface effectiveness are investigated. The theory describing an ensemble of dipole antenna elements that conform to the shape of a section of the joined wing is developed. The far held flee space radiation pattern of the sensor is then analyzed for a wing that is deflected due …

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The Air Warrior's Value Of National Security Space, John D. Loftis Mar 2003

The Air Warrior's Value Of National Security Space, John D. Loftis

Theses and Dissertations

The 2001 Report of the Commission to Assess United States National Security Space Management and Organization recommended that U.S. efforts in national security space be elevated to the highest national security priority. With more focused high-level attention on national security space decisions a measure that captures and quantities the value of space capabilities to combat operations professionals is desired. This thesis models what the air warriors desire from space assets in combat. A Value-Focused Thinking (VFT) approach was used to elicit values from air combat experts with operational experience. An initial Gold Standard value model was constructed and validated by …

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Multimission Aircraft Design Study: Electromagnetic Compatibility, Jenna M. Davis Mar 2003

Multimission Aircraft Design Study: Electromagnetic Compatibility, Jenna M. Davis

Theses and Dissertations

The multi-mission aircraft (MMA) technical feasibility study looked at the replacement of the aging fleet of C-135 and C-130 theater based command & control (C2) and intelligence, surveillance and reconnaissance (ISR) fleet. It is proposed that the MMA be out-fitted to combine some or all the functions of existing AWACS, JSTARS, RIVET JOINT, COMPASS CALL, and ABC CC platforms. It would also have links to other manned or unmanned ISR aircraft, as well as satellites. The objective of the proposed design study is to examine the technical risks involved in combining multiple functions onto one aircraft that currently reside on …

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A Study Of Control Laws For Microsatellite Rendezvous With A Non-Cooperative Target, Troy A. Tschirhart Mar 2003

A Study Of Control Laws For Microsatellite Rendezvous With A Non-Cooperative Target, Troy A. Tschirhart

Theses and Dissertations

This study investigated the feasibility of using a microsatellite to accomplish an orbital rendezvous with a noncooperative target, with a focus on the control laws necessary for achieving such a rendezvous. The relative motions of the microsatellite and the target satellite are described using Hill's equations. The results of an investigation of two different controller methodologies show that an impulsive thrust controller based on the Clohessey-Wiltshire solution used little fuel, but was not very robust. A continuous thrust controller using a Linear Quadratic Regulator was found to be more robust, but used much more fuel. As a final solution, a …

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Orbit Determination For A Microsatellite Rendezvous With A Non-Cooperative Target, Brian L. Foster Mar 2003

Orbit Determination For A Microsatellite Rendezvous With A Non-Cooperative Target, Brian L. Foster

Theses and Dissertations

This study investigated the minimum requirements to establish a satellite tracking system architecture for a hostile "parasitic microsatellite" to rendezvous with a larger, non-cooperative target satellite. Four types of tracking systems and their capabilities were reviewed with emphasis on "low-technology" level and/or mobile systems which could be used by technologically unsophisticated state or non-state adversaries. With the tracking system architecture selected, simulated tracking data was processed with a non- linear least squares orbit determination filter to determine and/or update the target satellite's state vector.

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A Service Life Analysis Of Coast Guard C-130 Aircraft, Jonathan B. Duff Mar 2003

A Service Life Analysis Of Coast Guard C-130 Aircraft, Jonathan B. Duff

Theses and Dissertations

The U. S. Coast Guard, much like the rest of the Armed Services, is facing a dramatic transformation of its forces to meet current and future service requirements. The Coast Guard has responded to this transformation by initiating the Deepwater System, a complete review of the offshore mission requirements and the modernization of its infrastructure. In particular, Deepwater will review and modernize the Coast Guard's aviation assets, improving aircraft systems, airborne sensors, and communications and information management systems. However, these capability advancements will take time and money to implement, and will require careful management of the current resources to ensure …

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Investigation Of Doppler Effects On The Detection Of Polyphase Coded Radar Waveforms, Geoffrey G. Bowman Mar 2003

Investigation Of Doppler Effects On The Detection Of Polyphase Coded Radar Waveforms, Geoffrey G. Bowman

Theses and Dissertations

Special operations missions often depend on discrete insertion of highly trained soldiers into dangerous territory. To reduce the risk involved in this type of engagement, Low Probability of Detection radar waveforms have been designed specifically to defeat enemy passive radar detectors. These waveforms have been shown to perform well when the Doppler shift is minimal, but their performance degrades dramatically with increased frequency shifts due to Doppler effects. This research compares one known Low Probability of Detection waveform, based on Welti coding, with a radar waveform known to provide Doppler constancy, namely, one based on Frank coding. These waveforms are …

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Wlan Csma/Ca Performance In A Bluetooth Interference Environment, Randall B. Noel Mar 2003

Wlan Csma/Ca Performance In A Bluetooth Interference Environment, Randall B. Noel

Theses and Dissertations

IEEE 802.11 WLANs and Bluetooth piconets both operate in the 2.4 GHz Industrial Scientific and Medical (ISM) radio band. When operating in close proximity, these two technologies interfere with each other. Current literature suggests that IEEE 802.11 (employing direct sequence spread spectrum technology) is more susceptible to this interference than Bluetooth, which uses frequency hopping spread spectrum technology, resulting in reduced throughput. Current research tends to focus on the issue of packet collisions, and not the fact that IEEE 802.11 may also delay its transmissions while the radio channel is occupied by a Bluetooth signal. This research characterizes previously neglected …

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Analyze The Air Force Methods For Facility Sustainment And Restoration, Ronald C. Cole Mar 2003

Analyze The Air Force Methods For Facility Sustainment And Restoration, Ronald C. Cole

Theses and Dissertations

The Department of Defense (DoD) is improving the procedures for identifying, advocating, allocating funding, and accomplishing facility requirements to improve the readiness capability to support the mission. The purposes of this research were to fully explore the methodologies employed by the Air Force (AF) and try to capitalize on industry standard practices to improve the AF methods. Industry has conducted extensive research devoted to the development of predictive models to estimate facility maintenance or sustainment requirements. The DoD and the AF have already implemented the facility sustainment model (FSM) to predict facility sustainment requirements; now however, they are struggling with …

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An Economic Evaluation Of Binary Cycle Geothermal Electricity Production, Crissie D. Fitzgerald Mar 2003

An Economic Evaluation Of Binary Cycle Geothermal Electricity Production, Crissie D. Fitzgerald

Theses and Dissertations

The U.S. is heavily dependent on fossil fuels to produce electricity. Geothermal energy, the heat in the earth's crust, can provide an alternative source of energy for electricity production as well as reduce fossil fuel consumption. The economic analysis presented in this study focuses on binary cycle geothermal electricity production. Variables such as well flow rate, geothermal gradient and electricity prices were varied to study their influence on the economic payback period for binary cycle geothermal electricity production. Payback periods represent the amount of time (in years) necessary to recover initial costs of plant construction.

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A System Dynamics Approach For Information Technology Implementation And Sustainment, Nathan W. Fonnesbeck Mar 2003

A System Dynamics Approach For Information Technology Implementation And Sustainment, Nathan W. Fonnesbeck

Theses and Dissertations

The goal of this research is to bring a new, dynamic modeling perspective to organizational information technology (IT) implementation systems (using the Air Force GeoBase initiative as a real-world example) without compromising principles from the research literature. Undesired behavior patterns, from historically poor IT implementation performance, versus desired behavior patterns are incorporated into the model structure. Using a system dynamics approach, multiple simulation runs under various initial conditions and organizational contexts are performed and compared over a short-term versus a long-term period of time. Based on these simulation ruins, various mixes of management interventions, under varying conditions, are recommended to …

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Palladium-Catalyzed Destruction Of Nitro Aromatic-Contaminated Groundwater, Dennis Landon Phillips Mar 2003

Palladium-Catalyzed Destruction Of Nitro Aromatic-Contaminated Groundwater, Dennis Landon Phillips

Theses and Dissertations

Of the over 17,000 DoD sites that potentially require remediation, sites containing soil and groundwater contaminated by energetic compounds are prevalent (Larson et al., 2001). Production of energetics such as 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5 - trinitro- 1,3,5 -triazine (RDX), and octahydro-1,3,5,7-tetranitro- 1,3,5,7-tetrasocine (HMX) for use in munitions has created a DoD-wide problem due to improper disposal techniques (Price et al., 2001), Nitro aromatic compounds (NACs) similar to those used in explosives can also be found in insecticides, herbicides, pharmaceuticals, dyes, plastics, and many other commonly used products. The natural breakdown of these contaminants creates byproducts such as amines, which are known …

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Development And Simulation Of A Pseudolite-Based Flight Reference System, Terry J. Bouska Mar 2003

Development And Simulation Of A Pseudolite-Based Flight Reference System, Terry J. Bouska

Theses and Dissertations

Current flight reference systems are vulnerable to GPS jamming and also lack the accuracy required to test new systems. Pseudolites can augment flight reference systems by improving accuracy, especially in the presence of GPS jamming. This thesis evaluates a pseudolite-based flight reference system which applies and adapts carrier-phase differential GPS techniques. The algorithm developed in this thesis utilizes an extended Kalman filter along with carrier-phase ambiguity resolution techniques. A simulation of the pseudolite-based positioning system realistically models measurement noise, multipath, pseudolite position errors, and tropospheric delay. A comparative evaluation of the algorithms performance for single and widelane frequency measurements is …

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Feature Guided Image Registration Applied To Phase And Wavelet-Base Optic Flow, Kate R. Duffy Mar 2003

Feature Guided Image Registration Applied To Phase And Wavelet-Base Optic Flow, Kate R. Duffy

Theses and Dissertations

Optic Flow algorithms are useful in problems such as computers vision, navigational systems, and robotics. However, current algorithms are computationally expensive or lack the accuracy to be effective compared with traditionally navigation systems. Recently, lower accuracy inertial navigation systems (INS) based on Microelectromechanical systems (MEMS) technology have been proposed to replace more accurate traditional navigation systems.

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Ins Aiding Using Passive, Bearings-Only Measurements Of An Unknown Stationary Ground Object, Alec E. Porter Mar 2003

Ins Aiding Using Passive, Bearings-Only Measurements Of An Unknown Stationary Ground Object, Alec E. Porter

Theses and Dissertations

The theory for Inertial Navigation System (INS) aiding using passive, bearings only measurements of an unknown stationary ground object, in the vein of optical flow measurement, is developed. Stand-alone bearings-only measurements over time of an unknown, but stationary, ground object are shown to yield estimates of the aircraft’s aerodynamic angles, viz., the angle of attack and sideslip angle. Two new equations containing the aircraft’s angular navigation variables ψ, θ, φ, γ, H, and the aerodynamic angles are derived. This allows an update of the aircraft’s attitude, thus making INS aiding using passive, bearings-only measurements possible. Moreover, the use of stadiametry, …

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The Effects Of Gps M-Code On Radar Detection, Jae K. Yang Mar 2003

The Effects Of Gps M-Code On Radar Detection, Jae K. Yang

Theses and Dissertations

The GPS system is undergoing a modernization effort which will add several new signals to be placed at the L1, L2, and L5 frequency bands. One of the signals to be placed on L2 is a new military code (M-code) which may be transmitted at a higher power level than current GPS signals. Other users of the L2 frequency band are concerned with the potential interference that may be caused by the increase in power of the GPS signal. One particular use of the 1215-1400 MHz frequency band is Air Traffic Control (ATC) radar applications.

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