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20 Results

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
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: Randall Milanowski, Slaven Moro, Norm Hall, Raichelle Aniceto, Bert Vermeire, Neal Nicholson
August 21, 2017

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

ACM SIGCOMM

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, Ethan Katz-Bassett, Harsha V. Madhyastha, Hyojeong Kim, Italo Cunha, James Hongyi Zeng, James Quinn, Petr Lapukhov, Saif Hasan, Timothy Cui
July 21, 2017

Proton Testing Results for Kaman KD-5100 Differential Inductive Position Measuring Systems

Journal, IEEE Radiation Effects Data Workshop (REDW)

We report proton testing of a position measuring system, the Kaman KD-5100, with applications including mirror positioning for laser beam control. We measure a device response likely due to total ionizing dose and/or displacement damage.

By: Bart McGuyer, Bert Vermeire, Norman Hall, Randall Milanowski, Slaven Moro
July 21, 2017

Robocodes: Towards Generative Street Addresses from Satellite Imagery

CVPR 2017

This paper describes our automatic generative algorithm to create street addresses (Robocodes) from satellite images by learning and labeling regions, roads, and blocks. 75% of the world lacks street addresses.

By: Ilke Demir, Forest Hughes, Aman Raj, Kleovoulos Tsourides, Divyaa Ravichandran, Suryanarayana Murthy, Kaunil Dhruv, Sanyam Garg, Jatin Malhotra, Barrett Doo, Grace Kermani, Ramesh Raskar
July 17, 2017

Single Event Effect Assessment of a 1-Mbit Commercial MRAM

2017 Nuclear and Space Radiation Effects Conference (NSREC) Radiation Effects Data Workshop

Single event effect susceptibility of a 1-Mbit commercial MRAM was experimentally evaluated. The memory exhibited SEFIs when operated in a dynamic mode with an LET threshold of 2.29 MeV.cm2/mg and a saturated cross section of 2.2×10-4 cm2/device. The memory was not sensitive to SEL, SEU or MBUs.

By: Philippe C. Adell, Slaven Moro, Lionel Gouyet, Christian Chatry, Bert Vermeire
July 17, 2017

100/200 Gbps Optical Coherent DSP ASIC – SEE & TID Assessment

NSREC 2017

Experimental assessment of commercial 100/200 Gbps optical coherent DSP modem ASIC completed with 64 MeV and 480 MeV proton radiation test campaigns. Single event effect cross sections calculated and no performance degradation observed for proton fluence levels up to 1.27×10^12 p/cm^2 with equivalent total ionizing dose exposure to 170 krad(Si).

By: Raichelle Aniceto, Slaven Moro, Randall Milanowski, Christopher Isabelle, Norman Hall, Bert Vermeire, Kerri Cahoy