Optical Networks for Earth-Space Communications and Their Performance
This article describes optical subnets of ground based receiving stations for Earth-space optical communications.
optical↗
Engineering topics
Shaik, Kamran
Publications and source records attributed to Shaik, Kamran.
Progress on ten-meter optical receiver telescope
A ten-meter hexagonally segmented Cassegrain optical telescope is being considered at the Jet Propulsion Laboratory for use as a research and development facility for optical communications technology. The goal of the study is to demonstrate technology which can eventually be used to develop a network of such telescopes to continuously track and communicate with the spacecraft. Hence, the technology has to be economical enough to allow replication for a ground or space based network. As we need to collect signal photons only, the telescope cost can be substantially reduced by accepting lower image quality. An important design consideration for the telescope is its ability to look very close to the sun. The telescope for optical communications must function during the daytime. Indeed, for some planetary missions it may be necessary that the system be capable of looking within a few degrees of the sun. To enable this, a unique sunshade consisting of hexagonal tubes in precise alignment with the mirror segments has been proposed which will also serve as the support for the secondary. Recent progress on the design and analysis of such an optical reception station is discussed here.
Shaik, Kamran↗
A ten-meter optical telescope for deep-space communications
Optical communications using laser light in the visible spectral range is being considered for future deep-space missions. Such a system will require a large telescope in earth vicinity to be used as a receiving station for data return from the spacecraft. A preliminary discussion for a ground-based receiving station consisting of a 10-meter hexagonally segmented primary with high surface tolerance and a unique sunshade is presented.
Shaik, Kamran↗
Atmospheric transmission calculations for optical frequencies
A quantitative study of the transmission loss through the entire atmosphere for optical frequencies likely to be used for an earth-space communication link using existing data bases on scattering and absorption characteristics of the atmospheric constituents is presented.
Shaik, Kamran↗
Atmospheric propagation issues relevant to optical communications
Atmospheric propagation issues relevant to space-to-ground optical communications for near-earth applications are studied. Propagation effects, current optical communication activities, potential applications, and communication techniques are surveyed. It is concluded that a direct-detection space-to-ground link using redundant receiver sites and temporal encoding is likely to be employed to transmit earth-sensing satellite data to the ground some time in the future. Low-level, long-term studies of link availability, fading statistics, and turbulence climatology are recommended to support this type of application.
Churnside, James H.↗
Laser communications through the atmosphere
Atmospheric properties affecting laser propagation with reference to optical communications are reviewed. Some of the optical space network configurations and various diversity techniques that may need to be utilized to develop robust bi-directional space-earth laser communication links are explored.
Shaik, Kamran↗
A compact implementation of a real time acousto-optic synthetic aperture radar processor
The architecture of a real-time acoustooptic synthetic aperture radar processor is reviewed and recent efforts to develop a compact processor are presented. It employs an acoustooptic device operated in the space integrating mode to compress the signal in range.
Shaik, Kamran↗