Communication satellite power amplifiers: current and future SSPA and TWTA technologies

This study captures the state of current satellite transponder technology, specifically, solid-state power amplifiers (SSPAs) and traveling wave tube amplifiers (TWTAs), and describes expected future advances, including GaN SSPAs. The findings of five previous SSPA and TWTA studies, including the 1991 European Space and Technology Center study, the 1993 National Aeronautics and Space Administration study, and three Boeing studies conducted in 2005, 2008, and 2013, are tabulated and summarized. The results of these studies are then compared with new analyses of two validated sources of amplifier data: a commercially licensed database, Seradata's Spacetrak, and a publicly available database, Gunter's Space Page. The new analyses consider a total of 18,902 amplifiers (6428 TWTAs, 2158 SSPAs, and 10,316 unspecified amplifiers) onboard 565 communications satellites launched from 1982 to 2016. This new study contains the largest number of satellites and amplifiers to date and compares output power, redundancy, and bandwidth capabilities. We find an increase in output power from the 1993 study of >200% for Ku-band TWTAs and C-band SSPAs, and >1000% increase for C-band TWTAs. The ratio of operational to redundant amplifiers is 10 times higher for TWTAs than SSPAs, and the majority of amplifiers over the past 30 years operate with bandwidth less than 100 MHz. A second analysis is conducted using failure records and telemetry of 16 geostationary satellites equipped with 659 amplifiers: 535 SSPAs and 124 TWTAs. We find that <2% of TWTAs and 5% of SSPAs experience anomalies. Overall, this research was performed to update and clarify how the power and bandwidth needs and redundancy trends of the SatCom community have evolved over the past 30 years

Integration and Testing of the Nanosatellite Optical Downlink Experiment

CubeSat sensor performance continues to improve despite the limited size, weight, and power (SWaP) available on the platform. Missions are evolving into sensor constellations, demanding power-efficient high rate data downlink to compact and cost-effective ground terminals. SWaP constraints onboard nanosatellites limit the ability to accommodate large high gain antennas or higher power radio systems along with high duty cycle sensors. With the growing numbers of satellites in upcoming scientific, defense, and commercial constellations, it is difficult to place the high-gain burden solely on the ground stations, given the cost to acquire, maintain, and continuously operate facilities with dish diameters from 5 meters to 20 meters. In addition to the space and ground terminal hardware challenges, it is also increasingly difficult and sometimes not possible to obtain radio frequency licenses for CubeSats that require significant bandwidth. Free space optical communications (lasercom) can cost-effectively support data rates higher than 10 Mbps for similar space terminal SWaP as current RF solutions and with more compact ground terminals by leveraging components available for terrestrial fiber optic communication systems, and by using commercial amateur-astronomy telescopes as ground stations. We present results from the flight unit development, integration, and test of the Nanosatellite Optical Downlink Experiment (NODE) space terminal and ground station, scheduled for completion by summer of 2017. NODE’s objective is to demonstrate an end-to-end solution based on commercial telecommunications components and amateur telescope hardware that can initially compete with RF solutions at \u3e10 Mbps and ultimately scale to Gbps. The 1550 nm NODE transmitter is designed to accommodate platform pointing errors \u3c 3 degrees. The system uses an uplink beacon from the ground station and an onboard MEMS fine steering mirror to precisely point the 0.12 degree (2.1 mrad) 200 mW transmit laser beam toward the ground telescope. We plan to downlink to an estalblished ground terminal at the Jet Propulsion Laboratory (JPL) Optical Communications Telescope Laboratory (OCTL) ground station as well as the new low-cost 30 cm amateur telescope ground station design to reduce overall mission risk. Moving beyond our initial laboratory prototyping captured in Clements et al. 2016 we discuss recent progress developing and testing the flight electronics, opto-mechanical structures, and controls algorithms, including demonstration of a hardware-in-the-loop test of the fine pointing system, for both the space and ground terminals. We present results of over-the-air testing of the NODE system, as we advance from benchtop to hallway to rooftop demonstrations. We will present thermal and environmental test plans and discuss experimental as well as expected results

Nanosatellite optical downlink experiment: design, simulation, and prototyping

The nanosatellite optical downlink experiment (NODE) implements a free-space optical communications (lasercom) capability on a CubeSat platform that can support low earth orbit (LEO) to ground downlink rates>10  Mbps. A primary goal of NODE is to leverage commercially available technologies to provide a scalable and cost-effective alternative to radio-frequency-based communications. The NODE transmitter uses a 200-mW 1550-nm master-oscillator power-amplifier design using power-efficient M-ary pulse position modulation. To facilitate pointing the 0.12-deg downlink beam, NODE augments spacecraft body pointing with a microelectromechanical fast steering mirror (FSM) and uses an 850-nm uplink beacon to an onboard CCD camera. The 30-cm aperture ground telescope uses an infrared camera and FSM for tracking to an avalanche photodiode detector-based receiver. Here, we describe our approach to transition prototype transmitter and receiver designs to a full end-to-end CubeSat-scale system. This includes link budget refinement, drive electronics miniaturization, packaging reduction, improvements to pointing and attitude estimation, implementation of modulation, coding, and interleaving, and ground station receiver design. We capture trades and technology development needs and outline plans for integrated system ground testing.United States. National Aeronautics and Space Administration. Research Fellowship ProgramLincoln Laboratory (Lincoln Scholars)Lincoln Laboratory (Military Fellowship Program)Fundación Obra Social de La Caixa (Fellowship)Samsung FellowshipUnited States. Air Force (Assistant Secretary of Defense for Research & Engineering. Contract FAs872105C0002

Evaluation of the performance of coherent optical communications commercial DSP ASICs in low earth orbit radiation environments

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.Cataloged from PDF version of thesis.Includes bibliographical references (pages 115-120).Coherent optical communications systems on satellites have the potential to contribute meeting to world-wide data capacity demand. Digital signal processing (DSP) application specific integrated circuits (ASICs) for coherent optical communications systems, first developed in 2008 with current capabilities of over 100 Gbps for commercial terrestrial applications, are a key technology needed for space-based applications. However, in order to develop coherent optical communications systems for space applications, the performance of these commercial ASICs must be evaluated with consideration of the radiation effects from the space environment. This work investigates the performance of the Inphi CL2001OA1 optical coherent DSP ASIC in a low earth orbit (LEO) radiation environment and assesses whether this ASIC could be a viable option for a coherent optical communications system on a LEO spacecraft. The approach consists of simulation and experiment. First the radiation environment is modeled for three sample LEO orbits: International Space Station (ISS) orbit, 800 km polar orbit, and 1000 km 0° inclination, for 1-year, 5-year, and 10-year mission durations. Total ionizing dose (TID) requirements were determined for each mission and used to experimentally evaluate the TID tolerance of the CL20010A1. The CL2001OA1 on an evaluation board system (EVK) is modeled and simulations with Stopping Range In Matter (SRIM) program are used to simulate 64.0 MeV protons penetrating through the system. The SRIM simulations are used to calculate the proton energy levels entering the silicon active region of the CL2001OA1 and to determine the proton energy level sufficient for depositing ionizing dose in the active region and penetrating through the active region. The simulations determine the lower threshold of proton energy level needed for experimental testing. Two proton test campaigns of the CL2001OA1-EVK were completed at UC Davis Crocker Nuclear Laboratory (CNL) and Tri-University Meson Facility (TRIUMF) using energy levels of 64.0 MeV and 480 MeV, respectively. The CL2001OA1 ASIC survived and experienced no performance degradation from TID exposure up to 170 krad(Si). The measured CL20010A1 single event effect (SEE) cross section was 2.46x10-⁹ cm² at the 64 MeV proton energy level and 3.82x10-¹⁰ cm² at the 480 MeV proton energy level. The SEE cross section data from the proton test campaigns was used to calculate the CL20010A1 SEE rate for the sample LEO missions. The SEE cross section results were compared to the results from previous studies on proton-induced SEEs of other Complementary Metal Oxide Semiconductor (CMOS) devices with silicon active regions. Mitigation strategies against LEO radiation effects for the CL2001A1 are considered, such as spot shielding, strategic placement in spacecraft, incorporation of protective electronic devices in the circuit system design, and programming periodic CL20010A1 resets or full system power cycles. Expansion of this work, such as additional proton radiation test campaigns at different energy levels below 64.0 MeV and between 64.0 MeV and 480 MeV as well as heavy ion test campaigns to assess SEEs induced by heavy ions from galactic cosmic rays (GCRs) and solar energetic particles (SEPs), would provide additional insights on potential effects of the LEO radiation environment on the CL20010A1. Heavy ion test campaigns would provide SEE cross section data, which could be used to calculate the expected heavy-ion induced SEE rate for a given LEO mission. This work serves as an initial step toward the development of a DSP coherent optical communications transceiver for LEO satellite applications.by Raichelle Joy Aniceto.S.M

100 Gbps ptical coherent modem for low earth orbit optical inter-satellite links

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2020Cataloged from the PDF of thesis. "February 2020."Includes bibliographical references (pages 215-227).Free space optical communication (FSOC) provides a viable and cost-effective solution for future satellite systems with advantages in bandwidth, unregulated frequencies, and reduced system mass, volume, and power consumption in comparison with radio frequency systems. Several FSOC systems successfully demonstrated links between spacecraft and Earth ground stations as well as inter-satellite links. Commercial industry, including companies such as SpaceX and Telesat, have taken an interest in utilizing the benefits of FSOC for proposed LEO constellations and using optical inter-satellite links (OISLs) to reduce the need for expensive worldwide ground tracking networks. State-of-the-art FSOC space terminal data rate performance is 5.625 Gbps using coherent BPSK detection, achieved by the Tesat and DLR laser communication terminal (LCT) in 2008. The Tesat and DLR LCT demonstrated LEO to LEO OSLs over a link distance of 5100 km.Within the past decade, the terrestrial communications industry advances in optical coherent DSP ASICs and integrated fiber optic component packages have enabled high capacity optical coherent communications systems with data rates of 100 Gbps and greater. It is desirable to leverage the data rate performance and cost point of these technologies to develop a state-ofthe- art optical coherent modem system for FSOC space applications. The goal of this work is to develop an optical coherent communications modem for LEO-to-LEO inter-satellite links with improvement in data rate of 10 times the current state of the art of 5.6 Gbps using commercial off the shelf components, such as optical coherent DSP ASICs, coherent transmitters, coherent receivers, and lasers, with minimal modifications as needed for space use.This work focuses on developing an optical coherent communications modem for data rates up to 100 Gbps using commercial telecommunications industry components compatible with lOOG wavelength division multiplexed (WDM) coherent systems. We develop a process for selecting commercial optical coherent technologies that can meet performance requirements in a LEO space environment. We develop optical coherent modem hardware and assess the selected commercial optical coherent technologies for uses in the space environment. We identify and develop cost-effective modifications based on radiation characterization, ensuring that we can achieve successful space operation and meet performance requirements.by Raichelle Joy Aniceto.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Aeronautics and Astronautic

Assessment of gamma and proton radiation effects on 100 Gbps commercial coherent optical transceiver

© COPYRIGHT SPIE. The Acacia AC100M is a 100 Gigabits per second (Gbps) commercial, coherent optical transceiver module with digital signal processing (DSP) application specific integrated circuit (ASIC). The AC100M was characterized with noise-loaded input to simulate power-starved link operation on the receiver and decoder for performance testing. Gamma radiation and 65 MeV proton radiation test campaigns at Defense MicroElectronics Activity (DMEA) and UC Davis Crocker Nuclear Laboratory (CNL), respectively, were completed to assess single event effects (SEEs) and total ionizing dose (TID) effects on the AC100M. After exposure to gamma radiation with TID level of ∼13.7 krad(Si), communication with the AC100M module was lost and power cycling of the module and evaluation board could not restore nominal operation. The AC100M ASIC survived and experienced no performance degradation from proton equivalent TID exposure up to 66.7 krad(Si) with proton radiation. After proton equivalent TID level of 101 krad(Si), the AC100M did not functional nominally after power cycling. The calculated AC100M ASIC proton SEE cross section was 4.39×10-10 cm2 at the 65 MeV proton energy level

Proton Radiation Effects Assessment of a Commercial 12-Megapixel CMOS Imager

© 2017 IEEE. Commercial off-the-shelf 12-Megapixel CMOS image sensors were irradiated with 105 MeV protons - one part to a fluence of 4×1011 protons/cm2, and a second part to 2×1011 protons/cm2. Pixel brightness increases with fluence along with annealing effects are reported. No latch-up events or hangs occurred

Single Event Effect and Total Ionizing Dose Assessment of Commercial Optical Coherent DSP ASIC

© 2017 IEEE. 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 1.27×1012 p/cm2 with equivalent total ionizing dose exposure to 170 krad(Si)

Integration and Testing of the Nanosatellite Optical Downlink Experiment

Free space optical (FSO) communications have the potential to outperform traditional radio frequency data rates by orders of magnitude using comparable mass, volume, and power. The Nanosatellite Optical Downlink Experiment (NODE) is a 1.2U, 1 kg, 15 W, 1550 nm CubeSat downlink transmitter that uses a master-oscillator power amplifier configuration with a modest 1.3 mrad half-power beamwidth (HPBW) enabled by a microelectromechanical system (MEMS) Fast Steering Mirror (FSM) [1],[4]. NODE is designed to be compatible with the Portable Telescope for Lasercom (PorTeL) ground station [3],[6],[19], which has successfully demonstrated tracking of low Earth orbit objects to better than 5 arcseconds RMS. The flight-like opto-mechanical NODE engineering model has successfully passed vibration testing at qualification levels specified by NASA GEVS [9]. The engineering model has also passed thermal testing in vacuum under worst-case expected environmental loads, and component operational temperatures remained within limits. Tests of the opto-mechanical alignment and control algorithms meet +/- 0.05 mrad (3-sigma) for the space and ground terminals. We present results from the NODE engineering unit and flight unit development, integration, and testing, as well as interface test results with PorTeL

Heavy Ion radiation assessment of a 100G/200G commercial optical coherent DSP ASIC

© 2019 SPIE. Downloading of the abstract is permitted for personal use only. We assess the viability of a state-of-the-art 100G/200G commercial optical coherent DSP ASIC (16 nm FinFET CMOS technology) for space applications through heavy ion testing to (1) screen for destructive SELs and (2) observe for nondestructive heavy ion SEEs on the ASIC. The ASIC was exposed to heavy ion radiation while operating both optically noise-loaded uplink and downlink to an optical and quot;ground" modem. There were no destructive SEEs, such as SELs, observed from the heavy ion radiation test campaign