Enhancement of primary education using EDUSAT: Rajiv Gandhi project for EDUSAT supported elementary education network (RGPEEE) overview

Providing education access to the children in the age group 6–14 years is a constitutional obligation and challenge for the union as well state governments, as the development of elementary education is a key factor for a nation's development. Due to the non-availability of required number of trained and expert teachers’ knowledge-divide exists between students population of urban and rural/remote areas. To bridge this gap Distance Learning or Tele-education is the best option. A dedicated satellite for the purpose (EDUSAT) was launched on 20th September 2004 to serve the nation in all the education activities. It was decided to provide a Tele-education network in and around the Sidhi district of Madhya Pradesh, with uplink and studio facility (Hub) at Jabalpur (MP) and around 700 receive only terminals (ROTs) in various schools. Since the medium of teaching used in this network is Hindi, it was later decided to extend the coverage to connect around 50 primary schools with ROTs in six surrounding states viz. Jharkhand, Bihar, Chhatisgarh, Uttar Pradesh, Rajasthan and Uttaranchal. The network is configured as a DTH network using state-of-art digital technology, in Ku-band with 3.8 m antenna and 16 W power amplifier at Hub. The ROTs are designed to operate on solar power for 2.5 h continuously, taking into consideration the non-availability of primary power in the rural areas. The teachers of the schools are trained for the proper operations of the ROTs. The teachers of these rural schools also contribute to the content generation, with local relevance, in coordination with Indira Gandhi National Open University (IGNOU). At present the network with around 1000 ROTs is being utilized for 2 h per day. The RGPEEE network is in the process of being augmented with 32 satellite interactive terminals (SITs), to be used for teachers training. The project is being managed by two tier management system. In order to oversee the project implementation and monitoring an Apex Core Group, consisting of Apex Committee and Standing Committee, has been constituted. The Apex Committee takes care of policy decisions where as, the Standing Committee takes care of day to day affair.     

The Scanning Sky Monitor (SSM) on ASTROSAT

The Scanning Sky Monitor is one of the experiments onboard the ASTROSAT, an Indian multiwavelength astronomy satellite mission. This experiment will detect and monitor X-ray transients in the energy band 2–10 keV. It is similar in design to the ASM on RXTE. It consists of position-sensitive proportional counters with one-dimensional mask. We describe the configuration of the experiment. We also discuss some of the results obtained using a detector which has already been fabricated and tested in our laboratory.     

Micro- and mini-satellites of ISRO—technology and applications

With rich experience of the successful Indian remote sensing satellite series, Indian Space Research Organization (ISRO) has started theme-based satellites like Resourcesat and Oceansat. Further taking the advantage of the improved technologies in areas of miniaturization, the micro- and mini-satellite series have been started, which will provide opportunity for the payloads of stand-alone missions, for applications, study or research. These include payloads for Earth imaging, atmospheric monitoring, ocean monitoring, scientific applications, and stellar observation. The micro-satellites are of 100 kg class, planned with a payload of about 30 kg and 20 W power and mini-satellites of 450 kg class for payloads of 200 kg and power of 200 W. The first satellite in the micro-satellite series is an Earth imaging payload followed by the second satellite with scientific payloads with the participation of students. Further the scientific proposals for micro-satellites are under evaluation. Similarly the first two missions of mini-satellites are defined with first one carrying ocean and environment monitoring payloads followed by the Earth imaging satellite with multi-spectral camera with 700 km swath. The current paper touches upon the technology involved in realization of the micro- and mini-satellites and the scope of applications of the series.     

Sporadic emission of ultra high energy gamma rays from crab pulsar

In a further study of sporadic emission from pulsars we find evidence for short lived intense emission from the Crab pulsar.     

Development of digital interactive processing system for NOAA satellites AVHRR data

The paper discusses the digital image processing system for NOAA/AVHRR data including Land applications — configured around VAX 11/750 host computer supported with FPS 100 Array Processor, Comtal graphic display and HP Plotting devices; wherein the system software for relational Data Base together with query and editing facilities, Man-Machine Interface using form, menu and prompt inputs including validation of user entries for data type and range; preprocessing software for data calibration, Sun-angle correction, Geometric Corrections for Earth curvature effect and Earth rotation offsets and Earth location of AVHRR image have been accomplished. The implemented image enhancement techniques such as grey level stretching, histogram equalization and convolution are discussed. The software implementation details for the computation of vegetative index and normalized vegetative index using NOAA/AVHRR channels 1 and 2 data together with output are presented; scientific background for such computations and obtainability of similar indices from Landsat/MSS data are also included. The paper concludes by specifying the further software developments planned and the progress envisaged in the field of vegetation index studies.     

Noncosmological redshifts

Six decades ago Edwin Hubble found his velocity-distance relation that soon became the observational foundation of modern cosmology. According to the Cosmological Hypothesis (CH), all extragalactic objects — galaxies and the quasi-stellar objects — derive their redshifts from the expansion of the Universe. This article reviews the evidence for and against the CH. To what extent is it universal? Does it provide the entire redshift of an extragalactic object? If an extra, noncosmological component of redshift is present, what is it due to? On the observational side the evidence presented here is of three kinds: (i) evidence that is prima facie consistent with the CH, (ii) neutral evidence that can be reconciled with the CH with a few epicycles, and (iii) discordant evidence which, if accepted, suggests that some objects at least possess substantial noncosmological redshifts. The final part of this review discusses the various theories proposed to account for noncosmological redshifts and outlines further tests to establish the validity or otherwise of the CH.     

Spectral Location of Rayleigh and "m" Fading Signals in White Gaussian Noise

The classical problem is considered of locating a fading sinusoidal signal known to be present in one of several frequency " cells," each of which contains additive white Gaussian noise. The signal fading is assumed to follow the popular Rayleigh distribution, but generalizations tions to non-Rayleigh fading are included in terms of the " in" distribution due to Nakagami. The channel observation time is allowed to be either predetermined or variable (corresponding, respectively, to " fixed sample size" and " sequential" reception), and the practically important situation of intermittent signal transmissions is also examined. Results are in the form of optimal and near-optimal receiver structures, and of measures of performance.