Communication Channel Model of the Atmosphere for Optical Frequencies

In order to obtain high data rate T.V. picture transmissions from spacecrafts on planetary missions consideration has been given in the past to the use of laser communications systems. If no relay satellite is used a deep space laser communication link would involve propagation through the earths atmosphere to a ground based station. This paper gives consideration to the characteristic of the earths atmosphere as a communication channel. A channel model is given both for clear weather conditions and for inclement weather conditions. For clear weather conditions it is found that the laser atmosphere is a Quasi-Wide-Sense-Stationary correlated Scattering Channel (QWSSCS) which can be fairly accurately characterized by an array of variable gain, variable delay paths. Under inclement weather conditions the channel is characterized by a differential circuit model which is specified by the Input Delay- Spread Function. Data is compiled, for these two channel models, which describes the pertinent parameters/ such as, delay dispersion, tne amplitude distribution, amplitude power spectrum and the two dimentional spacial correlation function. It is found that for good weather conditions, pulses having widths of the order of 2 picosecond can be propagated through the whole atmosphere without appreciable distortion, whereas for inclement weather conditions one is limited to pulse widths of the order of nanoseconds

Annual Report... /

Descripció feta a partir de: 2020, el 28 abril 2021

Report on miner refuge chamber thermal analysis, Raytheon UTD, December 6, 2007: contract number 254-2008-M-23921, Task 1 deliverable item

"There are three objectives to this task: 1. For a given set of conditions, mine temperatures, and rock types, determine the potential effect of different rock types on heat dissipation based on observations made during the LLEM simulation tests; 2. Provide written summary of results from 1; 3. Develop and deliver a numerical model that would allow NIOSH to estimate the point, if any, when the apparent temperature inside the chamber would begin to adversely impact inhabitants." - p. 1"TD28ST1.""December 6, 2007."NIOSH contract 254-2008-M-23921 supports the agency's research into refuge alternatives in underground coal mines, as mandated in Section 13 of The Mine Improvement and New Emergency Response Act of 2006 ("MINER Act").Also available via the the World-Wide Web as an Acrobat .pdf file (60 KB , 6 p.).This report was prepared by Raytheon UTD, Waltham, MA under NIOSH contract 254-2008-M-2392

Report on miner refuge chamber displacement analysis, Raytheon UTD, December 11, 2007: contract number 254-2008-M-23921, Task 4: deliverable item for sub-tasks 1 and 2

"Task 4 examines the effect of a methane explosion on the dynamics of three miner's refuge chambers. This will help provide an initial understanding of the robustness of these chambers under possible mine emergency conditions. Specifically, the objectives for Sub Tasks 1 and 2 of Task 4 are as follows: 1. Determine the magnitude and type of possible motion for all three structures as a function of linear distance from the explosion; 2. Determine the anchorage forces required to limit or prohibit any motions determined in #1 above for all three structures." - p. 1"TD28ST2.""December 11, 2007."NIOSH contract 254-2008-M-23921 supports the agency's research into refuge alternatives in underground coal mines, as mandated in Section 13 of The Mine Improvement and New Emergency Response Act of 2006 ("MINER Act").Also available via the the World-Wide Web as an Acrobat .pdf file (139 KB , 10 p.).This report was prepared by Raytheon UTD, Waltham, MA under NIOSH contract 254-2008-M-2392

Raytheon cost reduction program : product excellence at minimun cost.

Description of various cost reduction programs

Value engineering and analysis.

A step-by-step guideline of value analysis. Includes an article--Value analysis job plan--by F. S. Sherwin