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24 Results

June 12, 2018

Development of a Receive Phased Array Antenna for High Altitude Platform Stations using Integrated Beamformer Modules

International Microwave Symposium (IMS)

This paper describes the development and test of an electrically steerable phased array antenna designed for implementation in multilayer circuit board architecture.

By: Will Theunissen, Vipul Jain, Gaurav Menon
May 16, 2018

Deep Learning Coordinated Beamforming for Highly-Mobile Millimeter Wave Systems


Supporting high mobility in millimeter wave (mmWave) systems enables a wide range of important applications such as vehicular communications and wireless virtual/augmented reality. Realizing this in practice, though, requires overcoming several challenges.

By: Ahmed Alkhateeb, Sam Alex, Paul Varkey, Ying Li, Qi Qu, Djordje Tujkovic
March 8, 2018

Generative Street Addresses from Satellite Imagery

ISPRS International Journal of Geo-Information

We describe our automatic generative algorithm to create street addresses from satellite images by learning and labeling roads, regions, and address cells. Currently, 75% of the world’s roads lack adequate street addressing systems. Recent geocoding initiatives tend to convert pure latitude and longitude information into a memorable form for unknown areas. However, settlements are identified by streets, and such addressing schemes are not coherent with the road topology.

By: Ilke Demir, Forest Hughes, Aman Raj, Kaunil Dhruv, Suryanarayana Murthy Muddala, Sanyam Garg, Barrett Doo, Ramesh Raskar
January 27, 2018

An Inverse-Kinematic Approach to Dual-Stage Servo Control for an Optical Pointing System

SPIE Photonics West

In free-space optical communication systems, narrow beam diameters necessitate precision pointing over a relatively wide field of regard. Control systems with such large dynamic range requirements sometimes employ multi-stage architectures, where a “coarse” mechanism provides low-bandwidth control over a large range of travel, and a “fine” mechanism provides high-bandwidth disturbance rejection over a limited range of travel. In such systems, the two stages must be coordinated in their dynamic response, so as to avoid undesirable coupling and even interference with each other. This topic has been studied in various literature – especially in the field of hard disk drives, but also for optical pointing systems. However, most of this literature considers systems where the output of the two stages combines by simple linear sum. Dual-stage control becomes even more challenging when the two stages combine via nonlinear kinematic relationships, as they would in an optical pointing system employing multiple gimbaled steering mirrors. This paper presents an approach for handling these nonlinear kinematic effects, and demonstrates the viability of this approach via simulation.

By: Eric D. Miller
January 14, 2018

Experimental Demonstration of Digital Pre-Distortion for Millimeter Wave Power Amplifiers with GHz Bandwidth

IEEE Radio Wireless Week (RWW)

This paper presents an experimental demonstration of digital pre-distortion (DPD) on E-band power amplifiers (PA) with GHz channel bandwidth.

By: Qi Tang, Hongyu Zhou, Abhishek Tiwari, Joseph Stewart, Qi Qu, Dawei Zhang, Hamid Hemmati
December 15, 2017

Mapping the world population one building at a time


Here, we present a computer vision method based on machine learning to create population maps from satellite imagery at a global scale, with a spatial sensitivity corresponding to individual buildings and suitable for global deployment.

By: Tobias Tiecke, Xianming Liu, Amy Zhang, Andreas Gros, Nan Li, Gregory Yetman, Talip Kilic, Siobhan Murray
November 14, 2017

Fine Pointing Concepts for Optical Intersatellite Links

International Conference on Space Optical Systems (ICSOS)

In this paper we present two fine pointing architectures that support high-accuracy pointing, while also featuring simplification of the small-space optical assembly hardware, reduction in the number and complexity of constituent components, full self-calibration capability, and relaxation of otherwise-strict, cost-driving subassembly requirements.

By: Eric Miller, Kevin Birnbaum, Chien-Chung Chen, Andrew Grier, Matt Hunwardsen, Dominic Jandrain
October 2, 2017

Assessment of Proton Radiation Effects on Hamamatsu InGaAs PIN Photodiodes and Simulated Radiation Responses Using Defect-Based TCAD Modeling

RADiations Effects on Components and Systems (RADECS)

Hamamatsu InGaAs PIN photodiodes were exposed to 105 MeV protons to a fluence of 2.55×1011 p/cm2 . Radiation induced increase in dark current was observed that appeared stable following room temperature annealing. A preliminary TCAD model was developed for use in mixed-mode simulation analyses.

By: Raichelle Aniceto, Randall Milanowski, Slaven Moro, Kerri Cahoy, Garrett Schlenvogt
October 2, 2017

Proton Test Results for a Commercial Fanout Buffer, a Variable Gain Amplifier, and a ±40V Operational Amplifier

RADiations Effects on Components and Systems (RADECS)

Advanced electronics systems require a wide variety of high-performance analog, mixed signal, and clock distribution microcircuits which aren’t readily available as space-qualified components.

By: Raichelle Aniceto, Randall Milanowski, Slaven Moro, Kerri Cahoy, Garrett Schlenvogt
August 21, 2017

Engineering Egress with Edge Fabric: Steering Oceans of Content to the World


This paper presents Edge Fabric, an SDN-based system we built and deployed to tackle the challenges of point presence for Facebook, which serves over two billion users from dozens of points of presence on six continents.

By: Brandon Schlinker, Hyojeong Kim, Timothy Cui, Ethan Katz-Bassett, Harsha V. Madhyastha, Italo Cunha, James Quinn, Saif Hasan, Petr Lapukhov, James Hongyi Zeng