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Full-Text Articles in Signal Processing
Gnss Software Defined Radio: History, Current Developments, And Standardization Efforts, Thomas Pany, Dennis Akos, Javier Arribas, M. Zahidul H. Bhuiyan, Pau Closas, Fabio Dovis, Ignacio Fernandez-Hernandez, Carles Fernandez-Prades, Sanjeev Gunawardena, Todd Humphreys, Zaher M. Kassas, Jose A. Lopez Salcedo, Mario Nicola, Mario L. Psiaki, Alexander Rugamer, Yong-Jin Song, Jong-Hoon Won
Gnss Software Defined Radio: History, Current Developments, And Standardization Efforts, Thomas Pany, Dennis Akos, Javier Arribas, M. Zahidul H. Bhuiyan, Pau Closas, Fabio Dovis, Ignacio Fernandez-Hernandez, Carles Fernandez-Prades, Sanjeev Gunawardena, Todd Humphreys, Zaher M. Kassas, Jose A. Lopez Salcedo, Mario Nicola, Mario L. Psiaki, Alexander Rugamer, Yong-Jin Song, Jong-Hoon Won
Faculty Publications
Taking the work conducted by the global navigation satellite system (GNSS) software-defined radio (SDR) working group during the last decade as a seed, this contribution summarizes, for the first time, the history of GNSS SDR development. This report highlights selected SDR implementations and achievements that are available to the public or that influenced the general development of SDR. Aspects related to the standardization process of intermediate-frequency sample data and metadata are discussed, and an update of the Institute of Navigation SDR Standard is proposed. This work focuses on GNSS SDR implementations in general-purpose processors and leaves aside developments conducted on …
Ion Gnss Software-Defined Radio Metadata Standard, Sanjeev Gunawardena, Thomas Pany, James Curran
Ion Gnss Software-Defined Radio Metadata Standard, Sanjeev Gunawardena, Thomas Pany, James Curran
Faculty Publications
The past several years have seen a proliferation of software‐defined radio (SDR) data collection systems and processing platforms designed for or applicable to satellite navigation (satnav) applications. These systems necessarily produce datasets in a wide range of different formats. To correctly interpret this SDR data, essential information such as the packed sample format and sampling rate is needed. Communicating this metadata between creators and users has historically been an ad‐hoc, cumbersome, and error‐prone process. To address this issue, the satnav SDR community developed a metadata standard and normative software library to automate this process, thus simplifying the exchange of datasets …
Object Detection With Deep Learning To Accelerate Pose Estimation For Automated Aerial Refueling, Andrew T. Lee
Object Detection With Deep Learning To Accelerate Pose Estimation For Automated Aerial Refueling, Andrew T. Lee
Theses and Dissertations
Remotely piloted aircraft (RPAs) cannot currently refuel during flight because the latency between the pilot and the aircraft is too great to safely perform aerial refueling maneuvers. However, an AAR system removes this limitation by allowing the tanker to directly control the RP A. The tanker quickly finding the relative position and orientation (pose) of the approaching aircraft is the first step to create an AAR system. Previous work at AFIT demonstrates that stereo camera systems provide robust pose estimation capability. This thesis first extends that work by examining the effects of the cameras' resolution on the quality of pose …
Verifying And Improving A Flight Reference System's Performance, Loren E. Myers
Verifying And Improving A Flight Reference System's Performance, Loren E. Myers
Theses and Dissertations
The 746th Test Squadron (746 TS) at Holloman AFB, NM operates the Ultra High Accuracy Reference System (UHARS) as part of its mission positioning and navigation test. This research presents a method for verifying the performance of a flight reference system using a Delta-Position velocity derived from radio navigation positioning measurements. The algorithm presented may utilize Global Positioning System (GPS) or the Locata ground based positioning system. In the latter case, Locata provides a velocity truth independent from GPS. The accuracy of Locata and GPS are assessed and UHARS velocity measurements are characterized both in nominal and GPS denied applications.
Gps Multipath Reduction With Correlator Beamforming, Jason M. Barhorst
Gps Multipath Reduction With Correlator Beamforming, Jason M. Barhorst
Theses and Dissertations
This research effort investigates the feasibility of beamforming using a single Global Positioning System (GPS) front end. Traditional methods of beamforming use multiple front ends, typically one per antenna element. By enabling a receiver to sample a switched antenna array, the hardware cost of implementing a GPS antenna array can be significantly reduced. Similar techniques of reducing the number of receivers have been used by Locata Corporation in the design of their non-GPS positioning systems. However, Locata Corporation's local transmitters provide a signal strength much higher than GPS's signal strength. For this reason, the inclusion of low-noise amplifiers into the …
Signals Of Opportunity Navigation Using Wi-Fi Signals, Wilfred E. Noel
Signals Of Opportunity Navigation Using Wi-Fi Signals, Wilfred E. Noel
Theses and Dissertations
Since GPS is generally limited to areas with clear sky view, additional methods of navigation are currently being explored. This thesis explores navigation using Signals of Opportunity(SoOP). The signals chosen for evaluation in this thesis are the common Internet IEEE 802.11a/g signals, or Wi-Fi. This thesis presents SoOP navigation based on cross-correlations of received data from multiple Wi-Fi stations. It shows the effectiveness of the methods using collected Wi-Fi signals in a real-world environment. By using simple statistical representations of collected data in large groups, or windows, cross-correlation calculations can produce timing offsets between simulated stations. The timing offsets, or …
Aiding Gps With Additional Satellite Navigation Services, Yasin A. Mutlu
Aiding Gps With Additional Satellite Navigation Services, Yasin A. Mutlu
Theses and Dissertations
In modern warfare navigation services are very important. GPS is currently providing service for accurate navigation, except in some areas, especially urban areas, where GPS signals cannot always be tracked by users. In these cases some additional navigation support could be provided by other global navigation satellite systems. If GPS is combined with other navigation systems than the navigation gap will be minor. In this thesis, the effect of combining GPS with other satellite navigation systems, specifically GLONASS, Galileo and Compass, is evaluated in terms of availability and position dilution of precision (PDOP) values. First, satellite constellations are simulated in …
Failure Detection Of A Pseudolite-Based Reference System Using Residual Monitoring, Michael A. Ciampa
Failure Detection Of A Pseudolite-Based Reference System Using Residual Monitoring, Michael A. Ciampa
Theses and Dissertations
The 746th TS uses a flight reference system referred to as the Central Inertial and GPS Test Facility (CIGTF) Reference System (CRS). Currently the CRS is the modern standard flight reference system for navigation testing, but high accuracy is dependent on the availability of GPS. A pseudolite system is currently being developed to augment the CRS and supply the capability to maintain high accuracy navigation under normal and jamming conditions. Pseudolite measurements typically contain cycle slips and other errors (such as multipath, tropospheric error, measurement noise) that can affect reliability. Past work relied on the receiver-reported signal-to-noise (SNR) value to …
Fusion Of Inertial Sensors And Orthogonal Frequency Division Multiplexed (Ofdm) Signals Of Opportunity For Unassisted Navigation, Jason G. Crosby
Fusion Of Inertial Sensors And Orthogonal Frequency Division Multiplexed (Ofdm) Signals Of Opportunity For Unassisted Navigation, Jason G. Crosby
Theses and Dissertations
The advent of the global positioning system (GPS) has provided worldwide high-accuracy position measurements. However, GPS may be rendered unavailable by jamming, disruption of satellites, or simply by signal shadowing in urban environments. Thus, this thesis considers fusion of Inertial Navigation Systems (INS) and Orthogonal Frequency Division Multiplexed (OFDM) signals of opportunity (SOOP) for navigation. Typical signal of opportunity navigation involves the use of a reference receiver and uses time difference of arrival (TDOA) measurements. However, by exploiting the block structure of OFDM communication signals, the need for the reference receiver is reduced or possibly removed entirely. This research uses …
Navigation Using Signals Of Opportunity In The Am Transmission Band, Jonathan A. Mcellroy
Navigation Using Signals Of Opportunity In The Am Transmission Band, Jonathan A. Mcellroy
Theses and Dissertations
Maintaining a precision navigation solution both in a GPS hostile jamming environment and also in a GPS non-compatible terrain area is of great importance. To that end, this thesis evaluates the ability to navigate using signals from the AM band of the electromagnetic spectrum (520 to 1710 kHz). Navigation position estimates are done using multi-lateration techniques similar to GPS. However, pseudoranges are created using Time Difference of Arrival (TDOA) distances between a reference receiver and a mobile receiver, allowing the mobile receiver to obtain absolute position estimates over time. Four methods were developed for estimating the cross-correlation peak within a …
Fusion Of Imaging And Inertial Sensors For Navigation, Michael J. Veth
Fusion Of Imaging And Inertial Sensors For Navigation, Michael J. Veth
Theses and Dissertations
The motivation of this research is to address the limitations of satellite-based navigation by fusing imaging and inertial systems. The research begins by rigorously describing the imaging and navigation problem and developing practical models of the sensors, then presenting a transformation technique to detect features within an image. Given a set of features, a statistical feature projection technique is developed which utilizes inertial measurements to predict vectors in the feature space between images. This coupling of the imaging and inertial sensors at a deep level is then used to aid the statistical feature matching function. The feature matches and inertial …
Evaluating The Correlation Characteristics Of Arbitrary Am And Fm Radio Signals For The Purpose Of Navigation, Bryan S. Kim
Evaluating The Correlation Characteristics Of Arbitrary Am And Fm Radio Signals For The Purpose Of Navigation, Bryan S. Kim
Theses and Dissertations
The Global Positioning System (GPS) provides position estimates on the Earth at anytime, anywhere and in any weather. However, to provide robust positioning, GPS requires an unobstructed path to satellite signals. As such, GPS performance generally degrades or becomes non-existent in environments such as large urban areas. This research investigates and analyzes the correlation characteristics of arbitrary AM and FM radio signals for the purpose of navigation. Simulations are conducted with different combinations of correlation methods (`fixed' or `varying'), modulation types (AM or FM), and signal types (song or voice). Out of the eight different variations considered, only two provided …
The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii
The Use Of X-Ray Pulsars For Aiding Gps Satellite Orbit Determination, Dennis W. Woodfork Ii
Theses and Dissertations
This research proposes the use of an existing "signal of opportunity" - namely x-ray pulsars - to improve the accuracy and robustness of the GPS satellite and clock estimation algorithm. Improvement in satellite and clock accuracy results in a direct benefit to the user. A simulation has been developed to determine the effects of using x-ray pulsar measurements on the GPS Operational Control Segment. The epoch-specific position, velocity, and clock errors of all GPS satellites in the constellation were estimated using both pseudoranges and time-difference-of-arrival (TDOA) measurements from pulsars. The primary measure of accuracy is a constellation Signal-In-Space Range Error …
Development And Testing Of A Multiple Filter Approach For Precise Dgps Positioning And Carrier-Phase Ambiguity Resolution, Paul E. Henderson
Development And Testing Of A Multiple Filter Approach For Precise Dgps Positioning And Carrier-Phase Ambiguity Resolution, Paul E. Henderson
Theses and Dissertations
The most precise relative positioning obtained using differential GPS depends on accurately determining carrier-phase integer ambiguities. To achieve high precision, many current static and kinematic algorithms use a floating-point solution until enough information becomes available to fix the carrier-phase ambiguities accurately. A mew method is presented that uses a multiple model Kalman filter to resolve the carrier-phase integer ambiguities. This method starts with the floating-point results, yet smoothly and rapidly attains the precision of the correct fixed-integer solution, eliminating the need to decide when to switch from the floating to the fixed-integer solution. This method is based on a theoretically …