Deep space optical communications.
Communications requirements for manned deep space missions, using optical links, with PPM, PCM/PL AND coherent reception for each link
COMMUNICATIONS SATELLITE↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Accelerometer-assisted tracking and pointing for Deep Space Optical Communications: concept, analysis and implementations
In this paper, we will present the concept of accelerometer-assisted tracking, error analysis, and progress made on its implementations.
free-space optical communication fine point contro↗
Optical Communications Study for the Next Generation Space Telescope
The Next Generation Space Telescope (NGST), part of NASA's Origins program, is a follow on to the Hubble Space Telescope expected to provide timely new science along with answering fundamental questions.
next↗
Optical Communications for NASA's Small Spacecraft Missions of the Future
NASA's space missions of the future will be dominated by more moderate sized mini- and micro- spacecraft. Such missions will place stringent requirements on the mass and power consumption required for the various spacecraft subsystems.
optical communications technology small spacecraft↗
Optical Communication Subsystem for the X200 Series of Planetary Missions
NASA has started a major new Advanced Deep Space System Development (a.k.a x2000) Program at JPL. The objective of this program is to develop and space-qualify (in a total system environment) advanced, cutting-edge technologies for the next generation of deep-space exploration missions.
Optical Communication Planetary Missions Fire and ↗
Blocking Losses on an Optical Communications Link
Many photon-counting photo-detectors have the property that they become inoperative for some time after detection event. We say the detector is blocked during this time.Blocking produces losses when using the detector as a photon-counter to detect a communications signal. In this paper, we characterize blocking losses for single detectors and for arrays of detectors. For arrays, we discuss conditions under which the output may be approximated as a Poisson point process, and provide a simple approximation to the blocking loss. We show how to extend the analysis to arrays of non-uniformly illuminated arrays.
blocked detectors↗
Implementation of a Coded Modulation for Deep Space Optical Communications
We present a field programmable gate array code (FPGA) implementation of a turbo-like decoder for a serially concatenated pulse-position modulation (SCPPM) code. NASA a developed this coded modulation scheme for deep space communications from Mars. Under a nominal mission condition, the decoder complexity by iteratively decoding the modulation and SCPPM coded system can operate within a one dB signal energy gap from capacity. The structure of SCPPM makes direct application of the conventional turbo decoding algorithm very inefficient. Here, we describe techniques to increase the throughput and performance of a hardware SCPPM decoder. using our optimizations, we demonstrate a 6 mega-bits per second (Mbps) decoder realization on a single FPGA. Extension toa higher data rate decoder using multiple FPGAs is readily achievable. Similar codes designed for the optical channel can benefit from our optimization techniques.
modulation↗
High-Rate Optical Communications Links for Virtual Presence in Space
As man continues the exploration of space, either from platforms in Earth-orbit or from missions to the bodies of our solar system, there will be an on-going need to keep the public engaged in the process so that the general populace can share in the excitement of discovery and the inquisitive (professional or student) can participate in the data mining.
Virtual↗
Free Space Optical Communication Utilizing Mid-Infrared Interband Cascade Laser
A Free Space Optical (FSO) link utilizing mid-IR Interband Cascade lasers has been demonstrated in the 3-5 micron atmospheric transmission window with data rates up to 70 Mb/s and bit-error-rate (BER) less than 10 (exp -8). The performance of the mid-IR FSO link has been compared with the performance of a near-IR link under various fog conditions using an indoor communication testbed. These experiments demonstrated the lower attenuation and scintillation advantages of a mid-IR FSO link through fog than a 1550 nm FSO link.
semiconductor lasers↗
Optical Communication Link Assessment Utilizing a Modulated Retro-Reflector on Mars
This work proposes the duplexing of an optical free-space (FS) communication link while minimizing the required power and complexity by using a modulated retro-reflector (MRR) within a system that is shown for a Mars orbiter and rover scenario. The MRR is placed on a planet’s surface while the laser source is on the orbiter to achieve satellite communications with surface locations. The information, which varies from raw sensor data to multimedia files such as videos and other media, can be sent through this communication path. Due to the use of an MRR, an alternative modulating scheme is required to interpret a distorted signal. The arrangement suggested to prove the capabilities of the link is a nested pulse-position modulation (PPM) structure. A link budget was derived to show the link characteristics of this proposed system.
Link Power Budget↗
Distributed processing and fiber optic communications in air data measurement
This paper describes the application of distributed processing, fiber optics, and hardware redundancy to collecting airstream data in Princeton's digitally controlled Variable-Response Research Aircraft (VRA). Microprocessor-controlled instrumentation packages in each wingtip of the aircraft collect angle-of-attack and sideslip data in digital form; after scaling, filtering, and calibrating the data, they send it to the aircraft's microprocessor Digital Flight Control System (micro-DFCS) via digital fiber optic data links. Each wingtip's package is independent of the other; therefore, the system has dual hardware redundancy. The fiber optic link design is presented as well as a description of the calibration and communications software. Translation of the system's dual redundancy into fault tolerance is also covered. Results of preliminary flight tests are included.
Farry, K. A.↗
Optical communications experiments at 6328 angstrom units and 10.6 mu
Laser transmitter and optical superheterodyne receiver performance tests at 6328 A, demonstrating aperture size effect and noncoherent operation superiority
Lucy, R. F.↗
Optical communications research to demonstrate 2.5 bits/detected photon
The transmission of information by optical signals over a space channel with a power efficiency of 2.5 bits/detected photon markedly increases the amount of information that can be transmitted to satellites. An account is given of the research program at the Jet Propulsion Laboratory that is attempting to demonstrate that optical signals can be used to transmit information over a space channel with this power efficiency. It is noted, however, that the ability to attain 2.5 bits/detected photon (or higher) depends heavily on the validity of the mathematical models used in the performance analysis. Therefore, verification of the channel dark current noise models is a crucial first step. Another prerequisite is a high-brightness, single-spatial mode laser emitter. It is believed that single spatial model devices with power outputs of about 1W can be achieved by coherently combining a number of GaAs lasers in what effectively amounts to a phased array.
Lesh, J. R.↗
Looking for Speed!! Go Optical Ultra-Fast Photonic Logic Gates for the Future Optical Communication and Computing
Recently, we developed two ultra-fast all-optical switches in the nanosecond and picosecond regimes. The picosecond switch is made of a polydiacetylene thin film coated on the interior wall of a hollow capillary of approximately 50 micron diameter by a photo-polymerization process. In the setup a picosecond Nd:YAG laser at 10 Hz and at 532 nm with a pulse duration of approximately 40 ps was sent collinearly along a cw He-Ne laser beam and both were waveguided through the hollow capillary. The setup functioned as an Exclusive OR gate. On the other hand, the material used in the nanosecond switch is a phthalocyanine thin film, deposited on a glass substrate by a vapor deposition technique. In the setup a nanosecond, 10 Hz, Nd:YAG laser of 8 ns pulse duration was sent collinearly along a cw He-Ne laser beam and both were wave-guided through the phthalocyanine thin film. The setup in this case functioned as an all-optical AND logic gate. The characteristic table of the ExOR gate in polydiacetylene film was attributed to an excited state absorption process, while that of the AND gate was attributed to a saturation process of the first excited state. Both mechanisms were thoroughly investigated theoretically and found to agree remarkably well with the experimental results. An all-optical inverter gate has been designed but has not yet been demonstrated. The combination of all these three gates form the foundation for building all the necessary gates needed to build a prototype of an all-optical system.
Abdeldayem, Hossin↗
Optical communications through atmospheric turbulence using photodetector arrays
Ground-based reception of optical signals from space suffers from degradation of the optical phase-front caused by atmospheric turbulence, leading to a reduction in the effective diameter of the receiving aperture and to random fluctuations of the point spread function in the focal plane.
optical↗
NASA Electronic Parts and Packaging (NEPP): Space Qualification Guidelines of Optoelectronic and Photonic Devices for Optical Communication Systems
Key elements of space qualification of opto-electric and photonic optical devices were overviewed. Efforts were concentrated on the reliability concerns of the devices needed for potential applications in space environments. The ultimate goal for this effort is to gradually establish enough data to develop a space qualification plan of newly developed specific photonic parts using empirical and numerical models to assess the life-time and degradation of the devices for potential long term space missions.
Kim, Quiesup↗
Radio Frequency and Optical Communication Link Trade Studies Between Earth, Deep Space Gateway and Lunar Surface
Efficient and accurate communication are two of the most important aspects in a communications system. Hence, it was pertinent that radio frequency (RF) and optical link budget analyses were understood inside and out by the two young careerists when performing this study. This report covers RF and optical trade studies performed between Earth, Deep Space Gateway (DSG), Orion, and the Moon’s lunar surface. Using criteria provided by NASA Headquarters, the links were statically driven allowing review of the systems without bandwidth limitations, spectrum allocations, and hardware implementations. This provided the chance to review the efficiency of the links as technology improves throughout the decades. A few select RF links were analyzed using repeaters while select optical links were compared with coded and uncoded modulation schemes. The results from these analyses again prove the tradeoff theories in communications systems.
Booth, Stephanie L.↗
Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application
Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few-mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r(sub 0)=8.6. Furthermore, the coupling loss of the few-mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array.
Tedder, Sarah A.↗