Involuntary Signal-Based Grounding of Civilian Unmanned Aerial Systems (UAS) in Civilian Airspace

This thesis investigates the involuntary signal-based grounding of civilian unmanned aerial systems (UAS) in unauthorized air spaces. The technique proposed here will forcibly land unauthorized UAS in a given area in such a way that the UAS will not be harmed, and the pilot cannot stop the landing. The technique will not involuntarily ground authorized drones which will be determined prior to the landing. Unauthorized airspaces include military bases, university campuses, areas affected by a natural disaster, and stadiums for public events. This thesis proposes an early prototype of a hardware-based signal based involuntary grounding technique to handle the problem by immediately grounding unauthorized drones. Research in the development of UAS is in the direction of airspace integration. For the potential of airspace integration three communication protocols were evaluated: LoRa WAN, Bluetooth 5, and Frequency Shift Keying (FSK) for their long range capabilities. Of the three technologies, LoRa WAN transmitted the farthest, however the FSK module transmitted a comparable distance at a lower power. The power measurements were taken using existing modules, however, due to LoRa using a higher frequency than the FSK module this outcome was expected

Continued study of NAVSTAR/GPS for general aviation

A conceptual approach for examining the full potential of Global Positioning Systems (GPS) for the general aviation community is presented. Aspects of an experimental program to demonstrate these concepts are discussed. The report concludes with the observation that the true potential of GPS can only be exploited by utilization in concert with a data link. The capability afforded by the combination of position location and reporting stimulates the concept of GPS providing the auxiliary functions of collision avoidance, and approach and landing guidance. A series of general recommendations for future NASA and civil community efforts in order to continue to support GPS for general aviation are included

IMPROVING DIGITAL HIGH FREQUENCY (HF) COMMUNICATIONS WITH MULTI-DIMENSIONAL CONSTANT ENERGY MODULATION IMPLEMENTATION

Approved for public release. Distribution is unlimited.Improved high frequency (HF) digital communication is desired in commercial and military applications, especially at sea where the primary digital communications is satellite communications (SATCOM). HF over-the-horizon (OTH) relays are often the alternative communication path when SATCOM is too costly or not available. Our work suggests using multiple-input multiple-output (MIMO), orthogonal frequency division multiplexing (OFDM), and various modulations in HF OTH communications to reduce the bit error rate (BER), improve data throughput in the allocated bandwidth, and potentially provide physical layer security through obfuscation. We implement MIMO, OFDM, and multi-dimensional constant energy modulation (CEM) by utilizing GNU Radio Companion (GRC) to program two NI Ettus X310 Software Defined Radios (SDR) in a 2x2 MIMO configuration. This is the first time CEM has been transmitted and received. Modulation and demodulation are successful for various file types. The 4D-16 CEM constellation and its BER are compared to that of quadrature phase shift keying (QPSK) and 16-quadrature amplitude modulation (QAM). Explanations of how CEM, OFDM subcarriers, and space time block codes (STBC) can provide frequency agility, throughput manipulation, and physical layer security are provided. Selected CEM constellations are presented.Lieutenant Commander, United States NavyApproved for public release; distribution is unlimited

Pseudolite Architecture and Performance Analysis for the FAA\u27s NextGen Airspace

By 2025 the FAA plans to have fully implemented its NextGen Airspace design. NextGen takes advantage of modern positioning technologies as well as automation, data sharing, and display technologies that will allow more efficient use of our ever busier National Airspace (NAS). A key element of NextGen is the transition from surveillance RADAR providing aircraft separation and navigation to the use of the GPS and Automatic Dependent Surveillance Broadcast (ADS-B). ADS-B couples the precision of the GPS with networked ground and airborne receivers to provide precise situational awareness to pilots and controllers. The result is increased safety, capacity, and access with reduced reliance on an outdated and costly existing infrastructure. Reliance on the vulnerable GPS requires a backup system with higher positioning accuracy than those that are in place today. The USAF 746th Test Squadron at Holloman AFB, in partnership with Locata Corp., has demonstrated an Ultra High Accuracy Reference System (UHARS) over the Holloman Range composed of pseudolites (ground based satellites) transmitting GPS like signals. This study evaluates the suitability of the UHARS when applied on a national scale to meet Alternate Precision Navigation and Timing (APNT) requirements. From a systems architecture perspective UHARS is evaluated against APNT CONOPs stated Operational Improvements and Scenarios. From a signal architecture perspective the UHARS is evaluated against frequency and bandwidth constraints, service volume requirements and positioning accuracy determined by NextGen Airspace aircraft separation criteria

Radio communication via near vertical incidence skywave system

Abstract. While the overall picture of our cutting-edge communication framework is one of high unwavering quality, the practical experience could be completely different during catastrophic situations, when communication services are disrupted due to damages in the communications infrastructure. Moreover, wireless connectivity in remote areas of the works is still a highly significant problem, with an estimated two billion people being outside of the connected world. This thesis studies the use of high frequencies communications as a way to address the abovementioned cases. High frequency (HF) communication utilizes radio waves between 3 and 30 MHz with the wavelengths of 100 to 10 m. The dominant means of long-distance communication in this band is skywave propagation, in which radio waves that are directed at an angle into the sky are reflected on Earth by the ionized layers of the atmosphere. HF ionospheric reflection technique is commonly used specifically for military, maritime, aeronautical, and emergency communication in remote areas, and as backup system. Factors such as season, sunspot cycle, solar activity, as well as polar aurora plays significant roles in the sustainability of HF radio communications. Propagation plays the most significant role while designing a communication network. Radio waves propagates with an objective of transmitting signal successfully without having an error. So, studies on wave propagation mechanisms, channel and noises are equally important. This thesis focuses on high frequency near vertical incidence skywave (HF NVIS) technology. NVIS, exploiting a frequency range of 2–10 MHz, can provide continuous coverage up to a couple of hundred kilometres from the transmitter without skip zone. NVIS operation is considered during disaster relief operations when infrastructure is severely damaged or where tactical communication is needed in military operations. NVIS operation requires the presence of substantial ionization in the ionosphere directly above the transmitter. For optimizing a NVIS communication system, the most important parameters to consider are elevation angle, fading, noise and polarization. Furthermore, NVIS operation requires careful selection of antennas, operating frequency, maximum usable frequency (MUF), lowest usable frequency (LUF), as well as frequency of optimum transmission (FOT) for successful communication. At the time of emergency, low data services such as voice and text could be easily established with NVIS system. A comprehensive overview of NVIS based on number of research articles is given which highlights ionospheric propagation, antennas, the operational use of HF communications, as well as applications. Further, we highlight the challenges with possible solutions, and future research direction to ensure NVIS system sustainability. From this literature review, the significant relationship between NVIS antenna and NVIS propagation mechanism is discussed. Furthermore, thesis provides a reference text to understand various elements of NVIS system and demonstrate how modern technology can be used to solve HF issues. We believe that this article will encourage more interests in addressing the technical challenges on the research and development of future HF radio communication systems

Wireless Digital Train Line for Passenger Trains \u2013 Phase 3

FR-RRD-0086-20-01-00In an extensive third phase of a Federal Railroad Administration-funded research project running from August 2020 through July 2022, a team at the Advanced Telecommunications Engineering Laboratory at the University of Nebraska-Lincoln designed, developed, and evaluated wireless communications architectures for rail services in North America, with a focus on high-speed rail services. During this phase, the team focused on mitigating a significant challenge, not only in the rail industry but in fact across all sectors: radio frequency (RF) spectrum scarcity. RF spectrum resources are a necessity for any wireless solution, and with the rapid proliferation of wireless services and applications in all aspects of daily life and society, RF resources are becoming overused and expensive to license. Therefore, the team studied RF spectrum already owned by the rail industry, but that may be abandoned, underused, or used only for legacy applications. Such bands are ideal candidates for modernization and re-use

Journal of Telecommunications and Information Technology, 2004, nr 4

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Department of Defense Dictionary of Military and Associated Terms

The Joint Publication 1-02, Department of Defense Dictionary of Military and Associated Terms sets forth standard US military and associated terminology to encompass the joint activity of the Armed Forces of the United States. These military and associated terms, together with their definitions, constitute approved Department of Defense (DOD) terminology for general use by all DOD components

Test and evaluation of a prototyped sensor-camera network for persistent intelligence, surveillance, and reconnaissance in support of tactical coalition networking environments

This thesis investigated the feasibility of deploying an integrated sensor-camera network in military and law enforcement applications. The system was built using entirely commercial-off-the-shelf technologies. The prototype used the unattended ground sensors combined with digital video surveillance cameras to provide accurate real-time situational awareness, persistent intelligence and remote security. A robust testing and evaluation plan was created to measure the system's performance based on specific metrics. The tests focused primarily on the capabilities of the sensor aspect of the network. Tests were conducted to determine the maximum detection range, probabilities of detection, maximum communications range, and battery life. Mathematical models were created to assist network planners. Additionally, the prototyped system was tested through field exercises as part of the Naval Postgraduate School's Coalition Operating Area Surveillance and Targeting System field demonstrations in California and northern Thailand. Although the sensing capabilities exceeded the minimum metrics, the system was not suitable for use in military applications. However, the prototyped network would work well in less demanding law enforcement environments. Additionally, the feasibility and the need to develop an integrated sensor-camera network were demonstrated.http://archive.org/details/testndevaluation109452780US Navy (USN) author.Approved for public release; distribution is unlimited