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11.
In this paper the dependence of the threshold CNR of a simple phaselocked demodulator on the frequency deviation of an FM signal has been evaluated by the concept of quasi-stationary approximation. Experimental findings have been presented in support of the theoretical conclusion. 相似文献
12.
D. Banerjee S. Vadawale 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
We present a forward modelling technique for calculating the surface X-ray spectra for a variety of lunar terrains. Our calculations considered variations in solar fluxes from solar quiescent condition to large flare activity (M1 flare), and expected elemental concentrations in the target, as well as yield, instrumental, and viewing geometry parameters for X-ray induced fluorescence from the lunar surface. Additionally, we present estimates of anticipated XRF signals from prominent Kα lines observable by a collimated 14 cm2 X-ray detector from a 100 km lunar orbit with ∼20 km spatial resolution. Our results show that Mg, Al and Si characteristic Kα lines can be observed for all solar conditions. The Ca Kα lines line can be differentiated from a fixed background during more energetic solar conditions such as C1 and M1 flares, whereas Ti and Fe lines are identifiable only during C1 and M1 solar flare conditions for Apollo 12 site composition. Both the Kα X-ray intensity ratios of Mg/Si and Al/Si correlate well with concentration ratios of Mg/Si and Al/Si, respectively, for B1 and M1 solar conditions. The Kα X-ray intensity ratios of Fe/Si and Ca/Si correlates with concentration ratios of Fe/Si and Ca/Si, respectively, for M1 solar condition. In principle, the modelling technique outlined here can be used to determine absolute elemental abundances (Mg, Al, Si, Ca, Ti and Fe) from X-ray spectra measured during recent and future lunar missions. 相似文献
13.
Y.B. Acharya S.K. Banerjee A. Jayaraman B.H. Subbaraya K.S. Appu V. Narayanan K. Chatterjee C.R. Sreedharan V.D. Grinchinko G.A. Khokin V.A. Kononkov I.S. Moshnikov S.P. Perov A.F. Chizhov O.V. Shtrikov K. Zalpuri S.C. Garg P. Subramanyam R. Vijaykumar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(6):59-68
An Indo-Soviet collaborative experiment on Ozonesonde Intercomparison was conducted at TERLS in March 1983. Thirteen rocket ozonesondes, eleven balloon ozonesondes and seven meteorological rockets were launched from Thumba. The rocket and balloon soundings were supported by on site Dobson spectrophotometric observations, surface ozone measurements as well as measurements with a Volz type filter photometer. The programme has yielded data on ozone vertical profiles from eleven rocketsondes, seven balloon-sondes and four sets of Umkehr observations. The data is studied with a view to intercompare the various sensors. 相似文献