A method for automatic detection of equatorial spread-F in ionograms

A method is presented for automatic detection of spread-F. The method is based on an image recognition technique and is applied to ionograms recorded at the ionospheric station of Tucumán (26.9°S, 294.6°E). The performance achieved is statistically evaluated and demonstrated with significant examples. The proposed method improves Autoscala's ability to reject ionograms with insufficient information, including those featuring Spread-F. Automatic identification of cases of spread-F is of additional interest in Space Weather applications, when it helps detect degraded radio propagation conditions.The present data analysis is a retrospective study but forms the basis for real-time application as an extension of Autoscala’s capabilities.     

ATS-6 Millimeter Wave Propagation and Communications Experiments at 20 and 30 GHz

The Applications Technology Satellite (ATS-6) Millimeter Wave Experiment, developed and implemented by the NASA Goddard Space Flight Center, has provided the first direct measurements of 20-and 30-GHz Earth-space links from an orbiting satellite. Studies at eleven locations in the continental United States were directed at an evaluation of rain attenuation effects, scintillations, depolarization, site diversity, coherence bandwidth, and analog and digital communications techniques In addition to direct measurements on the 20-and 30-GHz links, methods of attenuation prediction with radars, rain gauges, and radiometers were developed and compared with the directly measured attenuation. This paper presents a review of the major results of the first year of measurements with ATS-6, with emphasis on the impact of the measurements on millimeter wave space systems design.     

An analysis of selected software safety standards

Standards, draft standards, and guidelines that provide requirements for the assurance of high integrity software are studied. The focus is on identifying the attributes necessary in such documents for providing reasonable assurance for high integrity software, and on identifying the relative strengths and weaknesses of the documents. The documents vary widely in their requirements and the precision with which the requirements are expressed. Security documents tend to have a narrow focus and to be more product oriented, while safety documents tend to be broad in scope and center primarily on the software development process. It is found that overall there is little relationship between the degree of risk and the rigor of applicable standards. Recommendations are provided for a base standard for the assurance of high integrity software