Performance Degradation Due to Specular Multipath Intersymbol Interference

Plots of performance degradation are used to compare the effects of fading and intersymbol interference in a two- component specular multipath digital communications channel. Similar plots are then used to compare two practical receivers designed to combat the interference. Degradation plots are shown to allow easy identification of each receiver's range of usefulness, as well as identification of variance bounds demanded of channel parameter estimates which the receivers require.     

Attitude Determination Via Nonlinear Filtering

The theory of nonlinear filtering has been applied to the problem of the attitude determination of a satellite. Two approximation methods have been studied with a view to practical implementation. Computer simulation results are included.     

Logistics Transportation for Space Station Support

Logistics support of a long duration space station will dictate a high degree of space flight activity to rotate personnel and transport supplies and equipment. Systems characteristics and mission requirements for space station logistics have been analyzed within the context of a broad spectrum of space missions. Preliminary concepts for a space shuttle system (space transportation) have been developed. This system can support not only a space station program, but a wide variety of space missions for both NASA and the DOD.     

Temperature Cycling Effects on Solar Panels

Temperature cycling for more than 300 cycles and for temperatures down to - 175°C performed on soldered silicon cell assemblies with copper, Kovar, and molybdenum interconnectors showed a wide range in failures depending both upon the materials used and on interconnector thickness and substrate material. The solder fatigue failure rate is strongly dependent on stress level in agreement with analytical predictions.     

Comparisons between primrose lake (54°N, 110°W) ROCOB winds (20–60 km) and Saskatoon (52°N, 107°W) M. F. radar winds (60–110 km): 1978–1982

The development of the new CIRA will require the combination of winds from many sources, e.g. rockets (ROCOB) up to ～60 km, and radar winds ～60–110 km. Difficulties are that such rocket data have larger errors at 60–65 km, and tidal effects may become significant. Radar data for 60–80 km may also have tidal contamination, due to ? 16h of data per day: from 80–110 km tidal corrections are usually reliable.Comparisons are made between the unique Saskatoon MF radar set, which is continuous from mid 1978–1983, and the ROCOB data from Primrose Lake, which is only 340 km northwest. While the agreement is satisfactory, special care is required when matching the two regions: particular problems are the low rocket sampling rate, and the unexpectedly large amplitude of the diurnal tide. Important differences from the zonal winds of CIRA-72 emerge, especially in winter months. Meridional cross-sections differ from previous data models in the extent of the summer equatorward flow.     

Volume Properties for the Wideband Ambiguity Function

It is shown that the volume under the wideband ambiguity function is close to the square of the signal energy. The ambiguity volume is asymptotically conserved as the signal approaches the narrowband case. The narrowband ambiguity volume is a lower bound for the volume of the wideband ambiguity function.     

Effects of gravity perturbation on developing animal systems

Developing systems provide unique opportunities for analyzing the effects of microgravity on animals. Several unusual types of cells as well as various extraordinary cellular behavior patterns characterize the embryos of most animals. Those features have been exploited as test systems for space flight. The data from previous experiments are reviewed, and considerations for the design of future experiments are presented.     

The optical parameters of the atmosphere of Venus

This work is devoted to the derivation of the optical properties of the Venus atmosphere from “Venera-10” optical measurements. Within the framework of a two-layer model of Venus atmosphere it is found that in the spectral interval 0.52 – 0.85 μm the optical thickness of the upper cloud layer is ≈ 50 and the optical parameters of the lower layer are similar to the Rayleigh ones. Comparison is made between the measurements of radiation field within the atmosphere and the results of strict calculations. A preliminary conclusion is suggested that there are considerable numbers of aerosol particles with a radius ? 0.03 μm in the lower layer. The results of the upper boundary of the cloud layer is estimated to be ≈ 70 km.     

The variability of stratospheric nitrogen compounds observed by LIMS in the winter of 1978–1979

The LIMS experiment was launched on the Nimbus 7 satellite for the purpose of sounding the vertical structure of temperature and key upper atmosphere trace gases on a global scale. The technique of thermal infrared limb sounding was used to obtain measurements of O₃, H₂O, NO₂, and HNO₃. LIMS collected data almost continuously from late October to late May over the latitude range from 64°S to 84°N. Two of the gases, NO₂ and HNO₃, are important elements in the NO_x chain of chemical reactions leading to ozone destruction. We will describe results for these gases in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January–May 1979, when a major stratospheric warming occurred.     

X-ray diagnostics of globular clusters

The presence of compact X-ray sources in globular clusters allows diagnostic studies of both the X-ray sources themselves and the globular clusters to be carried out. A review of much of this work, primarily based on Einstein X-ray observations and supporting studies of globular clusters at radio through UV wavelengths, is presented. The compact X-ray sources in globular clusters are found to be compact binaries containing neutron stars and - in a separate lower luminosity component of an apparently bimodal luminosity function - possibly white dwarfs. Implications for the formation and evolution of compact binary X-ray sources in globular clusters and in the galactic bulge are discussed. In particular, new evidence is presented that the galactic bulge sources may be compact binaries in the remnants of disrupted globular clusters.