Communications

VCSEL Laser Array for Communications

Ames Research Center, Moffett Field, California Optical communications in terrestrial and space environments require transmitted signals on the order of 40 GHz and higher, because of the uncertain and changing transmission environments. A robust communications system is needed that will provide these frequencies and substantial discrimination between different signals, which permit switching times on the order of 0.25 ps, and that permit the use of two or more distinct signals.

Posted in: Briefs

Read More >>

Providing a Real-Time Audible Message to a Pilot

This real-time weather and environmental data reporting approach is useful for commercial airlines. Ames Research Center, Moffett Field, California An aircraft pilot would prefer to receive information on weather patterns, obstructions, and other conditions that may interfere with a flight plan, formal or informal, as the pilot’s flight proceeds, with a latency of no more than a few minutes. Learning of, and reacting to, a changing environment within minutes after the change is first observed and reported is not possible with pilot’s reports (PIREPs), as presently provided. Instead, receipt of a pilot’s report (PIREP) often occurs offline, before a pilot’s own flight has begun, and with an associated latency of one to six hours. The present invention, described as an audio twitter approach, removes most of the latency associated with a PIREP and allows expansion of, and selective filtering of, information that is directly useful to the recipient pilot (RP).

Posted in: Briefs

Read More >>

Pass Plan Formatter (PPF) for Earth Sciences Ground Support System

Goddard Space Flight Center, Greenbelt, Maryland The TRMM (Tropical Rainfall Measuring Mission) and Terra ESMO (Earth Science Mission Operations) Ground Systems needed a method of passing scheduling data through the Goddard Mission Services Evolution Center (GMSEC) bus to other subsystems without modifying the Planning and Scheduling systems and their planning data output. The original output data is used by other subsystems and not just for automation with GMSEC.

Posted in: Briefs, TSP

Read More >>

Integrated Tool Archives, Extracts, and Analyzes Spacecraft Housekeeping Telemetry Data (GMSEC R3.0)

Goddard Space Flight Center, Greenbelt, Maryland The Integrated Trending and Plotting System (ITPS) is a comprehensive tool for storage, extraction, analysis, and plots of spacecraft housekeeping telemetry data (GMSEC R3.0 — Goddard Mission Services Evolution Center). ITPS reports information to engineers, ground controllers, and scientists regarding status and health of spacecraft and instruments. This innovation was developed to support and advance GMSEC new technology in control center development that enables the interoperability of MOC (Mission Operations Center) software components via a middleware messaging system.

Posted in: Briefs, TSP

Read More >>

Low-Noise Analog APDs with Impact Ionization Engineering and Negative Feedback

The technology can be used in active remote sensing optical instruments. Goddard Space Flight Center, Greenbelt, Maryland Silicon avalanche photodiodes (Si APDs) have low dark current and low excess noise factor, and are currently used in many of NASA’s missions. Noise equivalent power (NEP) of 40 to 50 fW/(Hz)1/2 over 140-MHz bandwidth has been demonstrated for Si APDs. Si APDs have very low responsivity for wavelengths longer than 1.1 mm, and cannot be used in future NASA lidar missions that require low noise and large-area photodetectors operated in the shortwave infrared (SWIR) region. The need for high-performance fiber optic communications receivers has provided the impetus for substantial progress during the last two decades in the understanding and performance of InP-based APDs that exhibit high responsivity in the wavelength range from 0.9 to 1.7 mm.

Posted in: Briefs, TSP

Read More >>

Method to Improve Wireless System Communication Coverage in a Bended Tunnel Environment

Lyndon B. Johnson Space Center, Houston, Texas The conventional methods of improving wireless system coverage performance are to increase the transmitter power and/or antenna gain. The high transmit power could lead to more power consumption and RF exposure issues. The use of a high-gain antenna could lead to a larger antenna size and increased weight and volume. An alternative approach would be to capture the available signal power more efficiently without increasing the transmitter power and/or increasing antenna size.

Posted in: Briefs, TSP

Read More >>

Design for Improving the Flatness of Solar Sails

An optically flat solar sail could be useful in optical communication and solar energy applications. NASA’s Jet Propulsion Laboratory, Pasadena, California This work describes a discontinuous or segmented mirror whose overall flatness is less dependent on the limited tension that can be supplied by the booms. A solar sail is a large, nominally flat sheet of extremely thin reflectorized film rigidly attached to a spacecraft, enabling propulsion via solar radiation pressure. Rip-stop fibers embedded in the backside of the film — with diameters ≈100× the thickness of the film — are commonly used to arrest tear propagation, which can easily occur in the handling and/or deployment of these gossamer-thin structures. Typically, the thin film or membrane that is the sail is systematically folded to enable both volumetrically compact transportation to space and mechanized deployment. It is the aggressive folding and creasing of the thin film that limits the ultimate flatness that can be achieved.

Posted in: Briefs, TSP, Solar Power

Read More >>