A5014958719- GNSS positioning and interference
- Inertial Sensor and Navigation
- Indoor and Outdoor Localization Technologies
- Advanced Frequency and Time Standards
- Soil Moisture and Remote Sensing
- Ionosphere and magnetosphere dynamics
- Wireless Communication Networks Research
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Radio Wave Propagation Studies
- Target Tracking and Data Fusion in Sensor Networks
- Bluetooth and Wireless Communication Technologies
- Ocean Waves and Remote Sensing
- Power Line Communications and Noise
- Astronomical Observations and Instrumentation
- Satellite Communication Systems
- Antenna Design and Optimization
- Sensor Technology and Measurement Systems
- Coastal and Marine Dynamics
- Underwater Vehicles and Communication Systems
- Advanced Wireless Communication Techniques
- Air Traffic Management and Optimization
- Electromagnetic Compatibility and Measurements
- RFID technology advancements
- Direction-of-Arrival Estimation Techniques
University of Colorado Boulder
2014-2024
Institute of Navigation
2018-2021
University of Colorado System
2004-2020
Stanford University
2003-2020
University of Colorado Colorado Springs
2018
Tsinghua University
2017
Institut de Biologie systémique et synthétique
2017
Luleå University of Technology
1999-2015
University of Rochester
2007
Ohio University
1991-2002
The idea of Global Positioning System (GPS)/Global Navigation Satellite (GNSS) "spoofing," or the ability to mislead a satellite navigation receiver into establishing position time fix which is incorrect, has been gaining attention as spoofing become more sophisticated. Various techniques have proposed enable detection if being spoofed – with varying degrees success and computational complexity. In this paper, monitor in Radio Frequency (RF) front end using automatic gain control (AGC)...
A goal in the software radio design philosophy is to place analog-to-digital converter as near antenna possible. This objective has been demonstrated for case of a single input signal. Bandpass sampling applied downconvert, or intentionally alias, information bandwidth frequency (RF) signal desired intermediate frequency. The becomes more interesting when two distinct signals are received. traditional approach multiple would be bandpass sample continuous span spectrum containing all signals....
Global navigation satellite system (GNSS) reflectometry has emerged recently as a promising remote sensing tool to retrieve various geophysical parameters of the Earth's surface. GNSS-reflected signals, after being received and processed by airborne or spaceborne receiver, are available delay correlation waveforms delay-Doppler maps (DDMs). In case rough ocean surface, those characteristics can be related rms L-band limited slopes surface waves and, from there, wind speed. The raw signal...
The performance of various carrier recovery loop architectures (phase lock (PLL), Doppler-aided PLL, frequency (FLL), and FLL) in tracking weak GPS signals are analyzed experimentally validated. effects phase or detector design, oscillator quality, coherent averaging time, external Doppler aiding information on delaying loss quantified. It is shown that for PLLs the metric total jitter a reliable assessing low C/N provided bandwidth not too small (~> 5 Hz). For bandwidths small, accurately...
Low-cost MEMS-based IMUs, video cameras and portable GNSS devices are commercially available for automotive applications some manufacturers have already integrated such facilities into their vehicle systems. provides positioning, navigation timing solutions to users worldwide. However, signal attenuation, reflections or blockages may give rise positioning difficulties. As opposed GNSS, a generic IMU, which is independent of electromagnetic wave reception, can calculate high-bandwidth...
Abstract Monitoring sea level is critical due to climate change observed over the years. Global Navigation Satellite System Reflectometry (GNSS-R) has been widely demonstrated for coastal sea-level monitoring. The use of signal-to-noise ratio (SNR) observations from ground-based stations especially productive altimetry applications. SNR records an interference pattern whose oscillation frequency allows retrieving unknown reflector height. Here we report development and validation a complete...
<h3>Abstract</h3> Taking the work conducted by global navigation satellite system (GNSS) software-defined radio (SDR) working group during last decade as a seed, this contribution summarizes, for first time, history of GNSS SDR development. This report highlights selected implementations and achievements that are available to public or influenced general development SDR. Aspects related standardization process intermediate-frequency sample data metadata discussed, an update Institute...
The carrier-to-noise density ratio (C/N0) is considered an important parameter describing the GPS receiver performance. This paper compares performance of two popular coarse-acquisition (C/A) C/N0 algorithms appearing in literature: variance summing method (VSM) (Psiaki et al., 2003, Psiaki, 2001), and power (PRM) (Van Dierendonck, 1996, Sayre, 2003), terms their estimates 1) additive white Gaussian noise (AWGN), 2) narrowband continuous wave interference (CWI), 3) response to quantization...
Reflectometry of signals opportunity such as those emitted by a global navigation satellite system, known GNSS-R, has been developed over the past years technique with great potential for ocean scatterometry, among other applications. Different approaches have proposed to use GNSS-R remote sensing surface roughness. One them is based on deriving some descriptor/metric from measured delay-Doppler map (DDM) and directly relating it geophysical property scattering surface. For instance,...
Due to their weak received signal power, Global Positioning System (GPS) signals are vulnerable radio frequency interference. Adaptive beam and null steering of the gain pattern a GPS antenna array can significantly increase resistance sensors interference jamming. Since adaptive processing requires intensive computational beamsteering receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs). However, software implementation general-purpose processors...
Prior research has shown that the currently deployed geodetic global positioning system (GPS) stations can be used to measure snow depth in an area around antenna installation via GPS interferometric reflectometry (GPS-IR). Although such a technique provides advantages of large spatial coverage and high temporal measurement sampling, there are also drawbacks using equipment for this application. The is costly designed mitigate multipath signal, while sensing, reflective component contains...
Spoofing attacks are a major threat to civilian GNSS usage given the powerful impact that they have on receiver. Many different anti-spoofing techniques been developed in past years and best practices algorithms combine complimentary generate optimized protection. In this paper we utilize make use of outputs from commercial off shelf receivers. It combines observation power measurements control asymmetries correlation function. The technique’s nominal behavior is assessed using real datasets...
The Google Smartphone Decimeter Challenge (GSDC) was a competition held in 2021, where data from variety of instruments useful for determining phone's position (signals GPS satellites, accelerometer readings, gyroscope etc.) using Android smartphones were provided to be processed/assessed regard the most accurate determination longitude and latitude user positions. One tools that can utilized process GNSS measurements is RTKLIB. RTKLIB an open-source processing software tool used with...
A direct digitization approach greatly reduces the hardware requirements in traditional front end design. Further, that has been eliminated is typically source of a number potential difficulties including age-based, temperature-based, and/or nonlinear performance. This paper presents case study on design and implementation Global Positioning System (GPS) receiver end. First, sensitivity dynamic range issues for generic are discussed with particular attention given to unique approach. Second,...
Adaptive antenna array processing is widely known to provide significant anti-interference capabilities within a Global Navigation Satellite Systems (GNSS) receiver. A main challenge in the quest for such receiver architecture has always been computational/processing requirements. Even more demanding would be try and incorporate flexibility of Software-Defined Radio (SDR) design philosophy an implementation. This paper documents feasible approach real-time SDR implementation beam-steered...
Due to the ever-growing threat of GPS spoofing, it has become necessary for aviation sector develop an effective means detection. This article focuses on two complementary spoofing-detection techniques that are available commercial receivers and thus require no additional hardware operate. The primary methodology detection is using a combination radio power monitoring metrics, levering both automatic gain control C/N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"...
<h3>Abstract</h3> Global navigation satellite system (GNSS) location engines on Android devices provide and utility to billions of people worldwide. However, these currently have very limited protection from threats their position, navigation, time (PNT) solutions. External sources radio frequency interference (RFI) can render PNT information unusable. Even worse, false signals or spoofing a solution devices. To mitigate this, four detection methods were developed evaluated using native...
This paper presents a methodology to evaluate the position availability of automotive grade global positioning system (GPS) receivers intended for Telematics applications utilizing multichannel GPS satellite signal simulator in controlled laboratory environment. Initially, field testing two distinct was conducted an urban canyon environment and foliage assess each receiver's performance. Test scenarios were then developed on order create repeatable stimuli receivers. The take into account...