Measurement and Zero-delay Finding Techniques for Ultrashort Optical Pulses Using Light-emitting Diodes as Detectors

The focus of this research was on the testing and characterization of light emitting diodes (LEDs) when used as replacements for second harmonic crystals in optical autocorrelation measurements. A range of experiments were performed to determine the response of these devices under various operating conditions. The results of these experiments were found to be inconsistent with the majority of previous work, producing inaccurately wide pulse width measurements. The measurements also show signal shoulders which are separate from the autocorrelation peak. These shoulders extend over a very long range (several picoseconds), and have useful applications for finding the point of zero delay in experimental setups. Theoretical analysis supported by simulation was also performed to provide insight into the mechanism at work to produce these features. While further investigation is required, this research has produced two very useful results. The inaccuracy which has been discovered in the pulse width measurements has provided a cause for caution when using LEDs in autocorrelation systems. More importantly, a new application has been identified for these measurements, and this application is improved by the features that make autocorrelation measurement undesirable.Electrical Engineerin

Flight and Direct to Earth/Space Relay Communication System Architecture for GSFC CubeSat Missions

The CubeSat platform is finding increasing use in space science applications due to its low cost and comparative ease of launch. It is becoming a key scientific discovery tool in low Earth orbit (LEO) and beyond, including geosynchronous equatorial orbit (GEO), the Lagrange Points, Lunar missions, and more. The increasing complexity of these missions and their scientific goals must be supported by equal advancements in communications technology. Higher data rates and greater reliability are required every year. However, the reduced Size, Weight, and Power (SWaP) constraints of CubeSat platforms introduce unique challenges in the area of satellite communications. There is currently a lack of communication equipment tailored specifically to the CubeSat platform. This lack of standardized, tested equipment extends development time and reduces mission confidence. Furthermore, missions utilizing the CubeSat platform are often subject to more difficult design constraints. Antenna placement, size, and pointing are often subordinate to the requirements of the payload instruments and mission goals. Traditional link margin estimation techniques are insufficient in these cases, as they emphasize worst case scenarios. In reality the actual link parameters may vary widely even during a single pass. This presents new challenges in predicting communications performance and scheduling ground station contacts, but also new opportunities for improving efficiency. This paper presents the integration, testing, and validation process for a new software defined radio (SDR) designed for the CubeSat platform in conjunction with Vulcan Wireless, Inc. The SDR is planned for use on 5 upcoming CubeSat missions at NASAs Goddard Space Flight Center (GSFC) including a Geosynchronous Transfer Orbit (GTO) mission and it may also serve as a standard and well-tested option for future missions by enabling a standardized, rapid and low cost CubeSat communication system network integration process. Detailed simulations have been developed to estimate the communication performance of these missions, taking the unique antenna placements and attitude behavior of each satellite into account. These simulations allow a much more accurate analysis of the expected link margin, which varies considerably during each pass for the NASA Space Relay (SR) and Direct to Earth (DTE) network. The modelling procedures are outlined, and the results are used to predict communications performance of the missions

Towards High Data Rate Hybrid RF/Optical Lunar Communication Architecture

Background Motivation Lunar science and exploration is set to explode in the coming decade. NASA\u27s Artemis Project will send first woman and next man to the moon by 2024 [1]. Dozens of additional Lunar missions are planned by 2028 [2]. Lunar missions will include human crews, rovers, smallSats, and more These missions will require a reliable and high data rate network

2020 Strategic Analysis of Energy Storage Technology

As California progresses towards its goal of 33 percent renewable electricity generation, the potential for energy storage to help integrate renewable resources and maintain a reliable and efficient electric grid takes on great significance. This report presents a strategic analysis of energy storage for California by 2020. The report assesses current energy storage technologies, discusses the diverse policies affecting deployment in California, and outlines critical technology gaps, future research needs, and policy reforms. It also provides a reference framework for the Energy Commission, CPUC, and other regulatory agencies to use as they develop solutions for how commercially ready energy storage technologies can be cost-effectively applied in California to reduce costs to ratepayers, reduce emissions from fossil fuel generation, and enable and accelerate the implementation of more renewable generation and its integration in California’s electricity system

GNU Radio

GNU Radio is a free & open-source software development toolkit that provides signal processing blocks to implement software radios. It can be used with readily-available, low-cost external RF hardware to create software-defined radios, or without hardware in a simulation-like environment. It is widely used in hobbyist, academic, and commercial environments to support both wireless communications research and real-world radio systems