A5056311235- Advanced Frequency and Time Standards
- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Astro and Planetary Science
- Acoustic Wave Resonator Technologies
- Planetary Science and Exploration
- Spacecraft and Cryogenic Technologies
- Solar and Space Plasma Dynamics
- Geophysics and Sensor Technology
- Satellite Communication Systems
- Scientific Measurement and Uncertainty Evaluation
- Ionosphere and magnetosphere dynamics
- Scientific Research and Discoveries
- Structural Analysis and Optimization
- Advanced Measurement and Metrology Techniques
- Radio Astronomy Observations and Technology
- Aerospace Engineering and Energy Systems
- Air Traffic Management and Optimization
- Spacecraft Design and Technology
- GNSS positioning and interference
- Space Satellite Systems and Control
- Advanced MEMS and NEMS Technologies
- Energy Harvesting in Wireless Networks
- Soil Moisture and Remote Sensing
- Advancements in PLL and VCO Technologies
Johns Hopkins University Applied Physics Laboratory
2002-2020
Johns Hopkins University
2006-2020
Westinghouse Electric (United States)
1987-2003
The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on Probe Plus is a four sensor instrument suite that provides complete measurements of the electrons ionized helium hydrogen constitute bulk solar wind coronal plasma. SWEAP consists Cup (SPC) Analyzers (SPAN). SPC Faraday looks directly at Sun measures ion electron fluxes flow angles as function energy. SPAN an electrostatic analyzer (ESA) ram side SPP (SPAN-A) ESA anti-ram (SPAN-B). SPAN-A has time flight section enables it...
The Solar Probe Cup (SPC) is a Faraday instrument onboard NASA's Parker (PSP) spacecraft designed to make rapid measurements of thermal coronal and solar wind plasma. in heliocentric orbit that takes it closer the Sun than any previous spacecraft, allowing be made where plasma being heated accelerated. SPC was pointed directly at all times, (which flowing primarily radially away from Sun) measured throughout orbit. capable measuring ions with an energy/charge between 100 V 6000 (protons...
The NASA Double Asteroid Redirection Test (DART) is a technology demonstration mission that will test the kinetic impactor technique on binary near-Earth asteroid system, Didymos. Didymos an ideal target, since 780 m primary, A, well characterized, and 163 secondary, B, sufficiently small to allow measurement of deflection. also represents population Near Earth Objects are asteroids most likely pose near-term threat Earth. Scheduled launch in June 2021, DART spacecraft autonomously intercept...
The Johns Hopkins University Applied Physics Laboratory (APL) has adopted an integrated electronics module (IEM) approach for many of its spacecraft programs. As a result APL developed relatively simple X-band transceiver that allows the telecommunications subsystem to be manufactured on plug-in cards fit into IEM. An issue with is downlink frequency not related uplink frequency. noncoherent relationship between and signals implications in both Doppler tracking ranging. method performing...
Current ultra-stable oscillator (USO) technology relies on highly precise quartz resonators that are selected based the desired output frequency and stability. These constraints crystal specifications significantly increase lead time expense of each USO. Recent research development efforts in USOs by The Johns Hopkins University Applied Physics Laboratory (JHU/APL) have focused a synthesized USO standardized, fixed-frequency resonator. result these is will provide reference for transponders...
Previous experiments have shown that the frequency shifts from low dose irradiation of quartz by protons recover and no correlation these to aluminum ion concentration was found. The authors previous posit variation in radiation sensitivity resonators a manufacturing lot dependence which confounds general analysis mechanisms relating material properties, impurity defects cut angle. Our work further explores discoveries using detail observed screening SC-cut for proton sensitivity....
This paper provides a detailed description of the radio communications system developed for Comet Nucleus Tour (CONTOUR) Project. The embodies delicate balance minimizing cost while providing high performance needed to support deep-space science mission. CONTOUR employs transceiver-based X-band instead traditional transponders. For navigation, we have conventional ranging channel and employ novel Doppler frequency measurement technique. A reference oscillator with low phase noise is included...
The author describes the performance and some of design features a dual-frequency synthesizer developed built for topography experiment (TOPEX) program. space-qualified generates high-quality 4.096-MHz 19.056391-MHz radio-frequency signals from 5-MHz reference source use by Global Positioning Satellite TDRSS transponder equipment aboard TOPEX-Poseidon satellite. Two voltage-controlled crystal oscillators (VCXOs) phase locked to oscillator are employed ensure excellent long-term stability....
The design of a 30-kW, L-band solid state transmitter for the look-down radar used on tethered aerostat system deployed to combat drug smugglers is described, and features components are discussed. This replaces tube previously in this type radar, resulting significantly improved reliability, maintainability, availability, 30% decrease overall weight. has large amount inherent redundancy which ensures specifications met while allowing individual transistor failures occur. Built-in test,...
This paper gives a brief overview of the EHF antenna demonstrators designed, developed, integrated and tested at Dornier Satellitensysteme GmbH (DSS). The Spotbeam demonstrator forms compact, high performance combined transmit/receive antenna. complete consists of: an offset parabolic main reflector, planar frequency selective surface as sub-reflector, transmit feed system with zooming capabilities, fully active receive system. A reflector 37-element, system, Globalbeam demonstrator.
We have reported on continuous improvements in the capability of our time and frequency laboratory. A substantial portion progress was achieved through incorporation new clock hardware, improvement GPS recovery coordination clocks into computation TAI. discussed ensemble hydrogen maser cesium beam atomic a timescale that enables UTC (APL) to be steered within plusmn 30 nanoseconds per month UTC. The propagation APL is based modified version Percival method, requiring regular characterization...