A5058658339- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Particle physics theoretical and experimental studies
- Soil Moisture and Remote Sensing
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Ocean Waves and Remote Sensing
- Inertial Sensor and Navigation
- Precipitation Measurement and Analysis
- Ionosphere and magnetosphere dynamics
- Oceanographic and Atmospheric Processes
- Underwater Acoustics Research
- Synthetic Aperture Radar (SAR) Applications and Techniques
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Stellar, planetary, and galactic studies
- Methane Hydrates and Related Phenomena
- Underwater Vehicles and Communication Systems
- Planetary Science and Exploration
- Advanced NMR Techniques and Applications
- Cryospheric studies and observations
- Advanced Electrical Measurement Techniques
- Remote Sensing and LiDAR Applications
- Climate change and permafrost
Jet Propulsion Laboratory
2002-2022
California Institute of Technology
2000-2021
University Corporation for Atmospheric Research
2021
Tarleton State University
2019
Olivet Nazarene University
2017
SLAC National Accelerator Laboratory
1985-1992
Stanford University
1986-1992
Stanford Synchrotron Radiation Lightsource
1986-1992
Space Information Laboratories (United States)
1990-1991
University of Wisconsin–Madison
1989
We present the first spaceborne observation of a Global Positioning System (GPS) signal reflected from Earth's surface, specifically Pacific Ocean. This result is scaled to obtain expected voltage signal‐to‐noise ratio (SNR) and altimetric accuracy for generic GPS reflections altimetry mission current SAC‐C CHAMP missions. Cross‐correlating three‐parameter phase model with both 1‐s 4‐s segment imaging radar‐C (SIR‐C) calibration data, recorded before after Galapagos Islands pass, results in...
We present the first two aircraft Global Positioning System (GPS)‐reflection altimetry measurements, most precise GPS ocean‐altimetry measurement, and demonstrate altimetric precision spatial resolution necessary to map mesoscale eddies. Our experiment demonstrated a 14‐cm single‐satellite ocean measurement while our more recent demonstrates 5 cm with 5‐km resolution. The new results show significant improvement over previous effort, due improved modeling, greater altitudes velocities,...
The reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ has been analyzed using 97 ${\mathrm{pb}}^{\ensuremath{-}1}$ of data taken with the Crystal Ball detector at DESY ${e}^{\ensuremath{-}}{e}^{+}$ storage ring DORIS II beam energies around 5.3 GeV. For first time we have measured cross section for $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$...
Abstract Information about wetland dynamics remains a major missing gap in characterizing, understanding, and projecting changes atmospheric methane terrestrial water storage. A review of current satellite methods to delineate monitor change shows some recent advances, but much improved sensing technologies are still needed for mapping, not only provide more accurate global inventories also examine spanning multiple decades. Global Navigation Satellite Systems Reflectometry (GNSS‐R)...
This work describes the first global scale assessment of a Global Navigation Satellite Systems Reflectometry (GNSS-R) experiment performed on-board Soil Moisture Active Passive (SMAP) mission for soil moisture and biomass determination. Scattered GPS L2 signals (1227.6 MHz) were collected by SMAP’s dual-polarization (Horizontal H Vertical V) radar receiver then processed on-ground using known replica L2C code. The scattering properties over land are evaluated Signal-to-Noise Ratio (SNR),...
Differences in electromagnetic path delay, between direct Global Positioning System (GPS) signals and those reflected from the surface of Crater Lake, have led to lake height estimates with 2‐cm precision 1 second. This is first high‐precision altimetric demonstration GPS sufficient altitude (≈ 480 m) probe fundamental experimental errors, which bear on future air‐and spaceborne passive altimetry. It also serves as a new approach remote sensing coastal region, an area that poorly measured by...
Large radio telescopes on Earth tracked the signal transmitted by Huygens probe during its mission at Titan. Frequency measurements were conducted as a part of Doppler Wind Experiment (DWE) in order to derive velocity direction Earth. The DWE instrumentation board consisted an ultrastable oscillator which maintained high stability required for determination horizontal motion atmospheric descent. A vertical profile zonal wind Titan's atmosphere was constructed from data under plausible...
GNSS reflection measurements in the form of delay-Doppler maps (DDM) can be used to complement soil from SMAP Mission, which has a revisit rate too slow for some hydrological/meteorological studies. The standard approach, only considers peak value DDM, is subject significant amount uncertainty due fact that DDM not affected by moisture, but also complex topography, inundation, and overlying vegetation. We hypothesize information entire 2D could help decrease under various conditions....
Global navigation satellite systems (GNSS) provide signals of opportunity for bistatic radar remote sensing, called GNSS reflectometry (GNSS-R), that have potential to be used ocean altimetry. These advantages over traditional mono-static include reduced cost, high density measurements in time and space, an inherent reference a highly accurate time-space frame. Here, we examine GNSS-R data collected from aircraft flying Monterey Bay, California. A downward-looking dual-frequency left-hand...
The reaction \ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$\ensuremath{\eta} has been investigated with the Crystal Ball detector at DESY storage ring DORIS II. Formation of \ensuremath{\delta}(980) and ${A}_{2}$(1320) observed \ensuremath{\gamma}\ensuremath{\gamma} partial widths ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}\ensuremath{\gamma}}$(${A}_{2}$)=1.14\ifmmode\pm\else\textpm\fi{}0.20\ifmmode\pm\else\textpm\fi{}0.2 6 keV...
The capability of global navigation satellite system reflectometry (GNSS-R) altimetry to map mesoscale sea surface height (SSH) fields is analyzed using synthetic measurements derived from a high-resolution (1/10°) numerical model the North Pacific. As an example, we consider GPS and GLONASS constellation transmitters assume six reflection-capable receivers onboard Constellation Observing System for Meteorology, Ionosphere, Climate satellites in high-inclination (720 km, 72°) orbits. An...
A delay/Doppler-mapping receiver system, developed specifically for global positioning system (GPS)-reflection remote sensing, is described, and example delay/Doppler waveforms are presented. The high-quality data obtained with this provide a more accurate detailed examination of ground-based aircraft GPS-reflection phenomenology than has been available to date. As an example, systematic effects in the reflected signal delay waveform, due nonideal behavior C/A-code auto-correlation function,...
view Abstract Citations (44) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Measurement of Planetary Relativistic Deflection Treuhaft, R. N. ; Lowe, S. T. The radio interferometric observations described here constitute the first measurement deflection electromagnetic radiation by a planetary gravitational field. They also demonstrate few hundred microarcsecond (µarcsec) angular astrometric technique, which can be applied over many-degree...
The Crystal Ball detector has been used at the DORIS II storage ring DESY to study reaction ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma}*\ensuremath{\gamma}*\ensuremath{\rightarrow}${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma}\ensuremath{\gamma}, where X is a narrow resonance with mass between 100 and 3000 MeV. Formation of...
Observations recorded by the NASA Cyclone Global Navigation Satellite System (CYGNSS) mission have demonstrated significant sensitivity to soil moisture, motivating development of several moisture products. An assessment these products was conducted CYGNSS science team. The results showed that accuracy each product may vary based on environmental factors such as surface roughness, vegetation, or terrain complexity. varied responses led an effort combine into a single blended product, best...
<h3>Abstract</h3> Radio frequency interference (RFI) in global navigation satellite system (GNSS) frequencies can endanger human life and safety by preventing the use of these signals for positioning, addition to degrading measurements science applications. Here, we data from Cyclone GNSS (CYGNSS) constellation map RFI 2017 2022, identify location several potential sources RFI, quantify duration transmission. Although our method detection only provide a rough approximation transmitter...
This paper presents an aircraft demonstration of direct-signal enhanced semicodeless processing global navigation satellite systems (GNSS) signals reflected from the Earth's surface. Comparisons are made between this new method and interferometric approach to GNSS reflectometry. Results show that technique produces waveforms with greater signal-to-noise compared for all currently in use or planned near future. Alternatively, can have similar performance smaller antennas lower hardware costs....
The inclusive photon spectrum in hadronic decays of the $\ensuremath{\Upsilon}(2S)$ is measured with Crystal Ball detector at DORIS II. Four well separated lines, which are consistent decay hypothesis $\ensuremath{\Upsilon}(2S)\ensuremath{\rightarrow}\ensuremath{\gamma}+^{3}P_{2,1,0}$ and $^{3}P_{2,1}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\Upsilon}(1S)$, observed. energies lines from primary transitions...
The authors present the first airborne ocean-altimetry measurement made using reflected GPS signals. Data were collected from a Cessna airplane flying off coast of Santa Barbara, California, where direct and ocean-reflected L1 signals downconverted recorded onboard at 20.456 MHz. In addition, processed with TurboRogue receiver used to derive accurate positioning. 20 MHz samples "software receiver", developed for this task, extract signal waveforms, both C/A Y-codes. These waveforms fit...
We have observed the Crab pulsar with Deep Space Network Goldstone 70 m antenna at 1664 MHz during three observing epochs for a total of 4 hr. Our data analysis has detected more than 2500 giant pulses, flux densities ranging from 0.1 kJy to 150 and pulse widths 125 ns (limited by our bandwidth) as long 100 μs, median power amplitudes 1 2 respectively. The most energetic pulses in sample energy fluxes approximately μs. used this large investigate number emission properties pulsar, including...