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Building upon multi-rate optical transceivers developed for both near-Earth and deep-space communications, we present scalable next-generation designs for future systems requiring more compact implementation and both power- and photon-efficient performance.
We discuss an optical ground terminal receiver architecture based on multi-aperture digital coherent combining. Experimental results using four receivers demonstrate lossless coherent combining in the laboratory at power levels below 0.1 photons/bit/receiver, and mitigation of scintillation through a 3.2-km free-space link due to spatial diversity.
Combining optical-phase-locked loop based coherent detection, interleaving, and powerful rate-½ FEC enabled the error-free transmission of BPSK waveforms at information rates of 9.94-Gb/s and 19.88-Gb/s with sensitivities of 2.1 photons-per-bit and 3.9 photons-per-bit, respectively.
The Lunar Laser Communications Demonstration (LLCD) is an ongoing project to demonstrate a high-rate, bidirectional optical communications link between a lunar satellite and an Earth-based ground terminal. The optical downlink operates at data rates up to 622 Mbps and employs photon counting array receiver technology. While the use of a 16-PPM modulation format with narrow (200 ps) slots gives rise...
Sensitive multi-rate optical communication is experimentally investigated on static and fading channels at data rates from 52 Mbps to 311 Mbps using 16-ary pulse-position-modulation, channel coding and interleaving, and a near-optimal thresholded preamplified receiver.
The topological changes in vertebral cancellous bone were estimated in vertebrae from calcium-restricted ovariectomized Sinclair S-1 minipigs, a recently described animal model of cancellous osteopenia. Connectivity was estimated using unbiased stereological principles in disector pairs of sections from the first lumbar vertebrae. Connectivity density was increased approximately twofold when compared...
Newly developed unbiased stereological methods were employed to investigate the effects of estrogen deficiency on the three-dimensional connectivity of vertebral cancellous bone from ovariectomized (OVX) rats. The effects of two classes of antiresorptive agents, estrogen and bisphosphonates, on changes in connectivity in this animal model were also evaluated. Female rats were either sham-operated...
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