scispace - formally typeset
Search or ask a question
Author

Vachik Garkanian

Bio: Vachik Garkanian is an academic researcher from Jet Propulsion Laboratory. The author has contributed to research in topics: Free-space optical communication & Optical communication. The author has an hindex of 4, co-authored 5 publications receiving 34 citations.

Papers
More filters
Proceedings ArticleDOI
12 Feb 2009
TL;DR: A canonical deep space optical communications transceiver which makes synergistic use of advanced technologies to reduce size, weight, power and cost has been designed and is currently under fabrication and test as mentioned in this paper.
Abstract: A canonical deep space optical communications transceiver which makes synergistic use of advanced technologies to reduce size, weight, power and cost has been designed and is currently under fabrication and test. This optical transceiver can be used to retire risks associated with deep space optical communications on a planetary pathfinder mission and is complementary to ongoing lunar & access link developments. Advanced technologies being integrated into this transceiver include use of a single photon-sensitive detector array for acquisition, tracking and communications; use of two-photon absorption for transmit beam tracking to vastly improve transmit/receive isolation; and a sub-Hertz break frequency vibration isolation platform is used to mitigate spacecraft vibration jitter. This article will present the design and current test results of the canonical transceiver.

10 citations

Journal Article
TL;DR: In this article, the authors used adaptive optics techniques to correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope, which facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.
Abstract: The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

9 citations

Proceedings ArticleDOI
TL;DR: In this paper, the authors describe the current performance of an adaptive optics testbed for optical communication, which allows for simulation of night and day-time observing on a 1 meter telescope with a 97 actuator deformable mirror.
Abstract: We describe the current performance of an adaptive optics testbed for optical communication. This adaptive optics system allows for simulation of night and day-time observing on a 1 meter telescope with a 97 actuator deformable mirror.

7 citations

Proceedings ArticleDOI
TL;DR: The Optical Ground Station 1 (OGS1) as discussed by the authors is the first dedicated ground terminal to support NASA's developing space-based optical communications infrastructure, which is based at NASA's Optical Communications Telescope Laboratory (OCTL) at the Table Mountain Observatory near Wrightwood, CA.
Abstract: Optical Ground Station 1 (OGS1) is the first of a new breed of dedicated ground terminals to support NASA’s developing space-based optical communications infrastructure. It is based at NASA’s Optical Communications Telescope Laboratory (OCTL) at the Table Mountain Observatory near Wrightwood, CA. The system will serve as the primary ground station for NASA’s Laser Communications Relay Demonstration (LCRD) experiment. This paper presents an overview of the OCTL telescope facility, the OGS1 ground-based optical communications systems, and the networking and control infrastructure currently under development. The OGS1 laser safety systems and atmospheric monitoring systems are also briefly described.

7 citations

Proceedings ArticleDOI
TL;DR: A detailed description of the experiment design for the uplink optical channel, in which 4 beacon lasers and 3 modulated communication lasers were combined and projected through the F/76 OCTL main telescope, is provided.
Abstract: The OCTL to OICETS Optical Link Experiment (OTOOLE) project demonstrated bi-directional optical communications between the JAXA Optical Inter-orbit Communications Engineering Test Satellite (OICETS) spacecraft and the NASA Optical Communications Telescope Laboratory (OCTL) ground station. This paper provides a detailed description of the experiment design for the uplink optical channel, in which 4 beacon lasers and 3 modulated communication lasers were combined and projected through the F/76 OCTL main telescope. The paper also describes the reimaging optical design employed on the acquisition telescope for receiving the OICETS-transmitted signal and the design of the receiver channel. Performance tests and alignment techniques of both systems are described.

4 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive survey on various challenges faced by free space optical communication (FSO) communication system for ground-to-satellite (G2S) or satellite-toground (S2G) and inter-Satellite (I2I) links.
Abstract: In recent years, free space optical communication has gained significant importance owing to its unique features: large bandwidth, license-free spectrum, high data rate, easy and quick deployability, less power and low mass requirements. FSO communication uses the optical carrier in the near infrared band to establish either terrestrial links within the Earth's atmosphere or inter-satellite or deep space links or ground-to-satellite or satellite-to-ground links. However, despite the great potential of FSO communication, its performance is limited by the adverse effects viz., absorption, scattering, and turbulence of the atmospheric channel. This paper presents a comprehensive survey on various challenges faced by FSO communication system for ground-to-satellite or satellite-to-ground and inter-satellite links. It also provides details of various performance mitigation techniques in order to have high link availability and reliability. The first part of the paper will focus on various types of impairments that pose a serious challenge to the performance of optical communication system for ground-to-satellite or satellite-to-ground and inter-satellite links. The latter part of the paper will provide the reader with an exhaustive review of various techniques both at physical layer as well as at the other layers i.e., link, network or transport layer to combat the adverse effects of the atmosphere. It also uniquely presents a recently developed technique using orbital angular momentum for utilizing the high capacity advantage of the optical carrier in case of space-based and near-Earth optical communication links. This survey provides the reader with comprehensive details on the use of space-based optical backhaul links in order to provide high-capacity and low-cost backhaul solutions.

479 citations

Proceedings ArticleDOI
12 Feb 2009
TL;DR: The Low Frequency Vibration Isolation Platform (LFVIP) as discussed by the authors reduces the resonant frequency of the mechanical oscillators into the sub-hertz region to maximize the passive vibration isolation.
Abstract: Mechanical resonators have been extensively used to provide vibration isolation for ground based, airborne, and spaceborne payloads. At low frequency, the effectiveness of these isolation systems is determined mainly by designing a mechanical oscillator with the lowest resonant frequency achievable. The Low Frequency Vibration Isolation Platform (LFVIP) reduces the resonant frequency of the mechanical oscillators into the sub-hertz region to maximize the passive isolation. This mechanical system, which has been expressly designed to isolate spacecraft vibrations from a compact deep space optical communication terminal, is based on the Stewart platform topology. Furthermore, the LFVIP provides tip/tilt functionality for acquisition and tracking of an optical beacon signal. An active control system is used for the DC positioning of the platform and the damping of the resonance of the mechanical oscillator. A summary of the LFVIP system, including analysis design, and preliminary results is presented.

19 citations

Proceedings ArticleDOI
11 May 2011
TL;DR: In this article, the laser beacon power required by a communication terminal for acquisition and tracking in deep space optical link scenarios can be reduced by a factor of 10 to 100 by replacing an integrating array, such as a CCD, with an array of single photon detectors.
Abstract: The laser beacon power required by a communication terminal for acquisition and tracking in deep space optical link scenarios can be reduced by a factor of 10 to 100 by replacing an integrating array, such as a CCD, with an array of single photon detectors. An additional benefit of the single photon detector array is that each pixel can have MHz bandwidths, allowing simultaneous recovery of photon time-of-arrival information that can be used for uplink data recovery or range measurements.

17 citations

01 May 2011
TL;DR: The Flight Laser Transceiver (FLT) as mentioned in this paper is a space-based subsystem of the Deep-Space Optical Terminals (DOT) project, which supports the retirement of all major risks for deployment of operational deep-space optical communications at ranges out to about 5 AU.
Abstract: The Flight Laser Transceiver (FLT) is the space-based subsystem of the Deep- space Optical Terminals (DOT) project. The FLT supports retirement of all major risks for deployment of operational deep-space optical communications at ranges out to about 5 AU. Architecture, key requirements, major trades results, selected concept design, required tech- nology maturation, and future scalability are discussed.

16 citations

Dissertation
01 Jan 2018
TL;DR: The Portable Telescope for Lasercom (PorTeLST) as mentioned in this paper is a low-cost optical ground station that uses a commercial off-the-shelf (COTS)-low-cost telescope.
Abstract: Small satellite technical capabilities continue to grow and launch opportunities are rapidly expanding. Several commercial constellations of small satellites for Earth observation and communications are making their way onto orbit, increasing the need for high bandwidth data downlink. Laser communications (lasercom) has the potential to achieve high data rates with a reduction in power and size compared to radio frequency (RF) communications, while simultaneously avoiding the significant regulatory burden of RF spectrum allocation. Lasercom benefits from high carrier frequencies and narrow beamwidths, but the resulting challenge is to precisely point these beams between transmit and receive terminals. Arcsecond to sub-arcsecond pointing is required from both the space terminal and the ground station. While existing lasercom ground stations have primarily utilized professional telescopes at observatory-class facilities, making optical ground stations more affordable and transportable is a key enabler for expanding lasercom to small satellites and new applications, as well as establishing networks to mitigate the effects of weather. This thesis focuses on the development of a portable optical ground station utilizing a commercial off-the-shelf (COTS), low-cost telescope. The Portable Telescope for Lasercom (PorTeL) reduces mass and cost by at least 10× compared with existing optical ground stations. To enable the use of a low-cost telescope, several contributions are made to the state-of-the-art approach to optical ground station design, pointing, and tracking. A system architecture is proposed that enables rapid deployment in approximately 30 minutes and that is capable of tracking satellites in low-Earth orbit (LEO) to within arcseconds of accuracy. A novel telescope calibration algorithm is developed that is agnostic to initial mount/telescope orientation and utilizes a star tracker for rapid, automated alignment. This eliminates the need for manual pre-alignment (e.g., leveling of the mount) and provides a generic framework that extends to different mount types. An approach to tracking LEO objects to better than 5 arcseconds RMS using only two-line element sets (TLEs) and low-cost hardware is presented. Pointing and tracking algorithms and performance are validated by using a physical ground station setup to track LEO objects, including the International Space Station (ISS).

16 citations