Satellite Radio , work

Satellite radio is such a remarkably simple concept that one might wonder why it took until 2001 for the first space-based audio service to make its debut in the United States.

At least it’s simple on the surface: Take a music, news or talk station, beam the signal up to a satellite, and overcome the limitations of ground-based transmitters whose signals generally drop off as distance increases. Then make sure the programming is more appealing than traditional radio stations and cut down on the number of commercials in exchange for a monthly subscription fee.

But as it turns out, satellite radio is a whole lot more complex than it seems on paper – and it took cutting-edge technology to make the systems operated by Sirius Satellite Radio and XM Satellite Radio work.

XM and Sirius are not the first companies to enter the satellite radio industry: Worldspace Corp., a firm based in Washington, has provided satellite radio in Asia and Africa since 1998. But Worldspace was intended primarily for use in fixed locations, while the systems used by XM and Sirius are optimized to reach U.S. listeners on the go.

From the ground up

It took a number of years to develop the XM and Sirius systems.

Engineers had to figure out how to squeeze dozens of individual channels into a relatively small amount of bandwidth and come up with reliable methods of beaming signals from thousands of miles in space to roving antennas smaller than tennis balls.

They also had to develop inexpensive circuitry, or chipsets, to enable receivers to decode the satellite signals, which are encrypted to prevent reception by non-subscribers. Both firms are working on newer versions of their chipsets that will be smaller and use less power.

Sirius and XM each took somewhat different approaches, although the end result, from a lay person’s perspective, is the same: 100 channels of music, news, sports and other fare available virtually anywhere in the continental United States. The companies are trying to distinguish themselves with programming and attitude.

XM’s system uses two very powerful satellites floating in space directly above the equator. The spacecraft are in geostationary orbit — they appear from the ground to remain in fixed perches, because they move around the Earth at the same speed the planet is rotating.

Geostationary satellites are commonly used for all sorts of space-based communications because they enable use of inexpensive, fixed antennas. Satellite TV and Internet systems are two examples of consumer-oriented technologies that use this type of satellite.

Repeat that, please

Since geostationary spacecraft are above the equator, terminals on the ground must have a decent view of the southern sky to receive signals from them. This posed a challenge for XM, since listeners in cars often pass by obstacles, such as buildings, foliage or hills, which can block geostationary satellite signals.

XM’s solution is a network of repeaters – antennas on buildings and other sites that receive satellite signals from an optimally placed antenna and retransmit them. The repeaters are located primarily in built-up areas, where loss of the satellite signal is most likely to occur.

Each XM receiver is equipped to receive signals from both of the company’s Boeing 702 satellites and a repeater simultaneously. As long as one of the sources is available, the radio will play without interruption. In addition, the receivers have buffers that store programming for several seconds, allowing operation to continue even if no signal is available momentarily.

Sirius uses a trio of Loral FS1300 satellites in unique elliptical orbits in an effort to avoid the problems posed by geostationary satellites.

The orbits, shaped like figure eights, allow the satellites to appear higher in the sky than XM’s, cutting down on the potential for a listener to be out of range of a satellite signal — and allowing Sirius to have a much smaller number of repeaters.

Sirius’ repeater network also avoids the need for specialized antennas that can track the company’s non-geostationary satellites as they move about the sky, Sirius feeds its repeaters using capacity on a geostationary satellite leased from a traditional satellite operator. Listeners can’t tell that the signals they receive via the repeaters do not travel over Sirius’ fleet of satellites.

The Sirius satellites each spend about 16 hours over the United States, then whip around the other side of the Earth and return eight hours later for another stint hovering over Sirius’ listening area, according to Ted Hessler, the company’s vice president of space segment and enterprise operations.

Two Sirius spacecraft cover the United States at any given time, Hessler said.

In the studio

XM and Sirius both operate digital broadcast centers that combine dozens of individual recording studios with huge amounts of storage to hold hundreds of thousands of compact discs worth of music in digital format.

Programmers just point and click at the material they want to play, and it airs directly from the storage system at the appointed time. During transmission, the system also adds a short description of the music or other material for display on a small receiver screen.

That is one unique advantage to satellite radio — you can find out the artist and song title as each piece of music plays.

The 22 terabytes of storage capacity at XM’s facilities in Washington can hold about 250,000 CDs, said Anthony J. Masiello, XM’s senior vice president of operations.

Terry Smith, senior vice president and chief technology officer of Sirius, said his company’s studios in mid-town Manhattan have about seven terabytes of storage. While that is less than XM has, Smith says it’s plenty.

“Our library is constantly being refreshed as new content comes in,” Smith said.

Both companies also maintain large collections of CDs to augment their digital libraries. They also retransmit programming that originates elsewhere, such as news, sports and comedy channels, and maintain studios where artists perform live.

Another, less visible key to satellite radio is digital compression, a technique to use radio spectrum as efficiently as possible. Both satellite radio broadcasters use sophisticated algorithms to squeeze as much material as they can into the available bandwidth without causing audio quality to degrade.

XM and Sirius are each allocated 12.5 megahertz of radio spectrum by the U.S. Federal Communications Commission. Get payday loan to make a payment.

Radio for distance education

Despite rapid developments in communication technologies in the last few decades, radio broadcasting remains the cheapest mode of mass communication in India that can benefit rural and deprived communities with low literacy rates and little excess to education.

At a recent conference on Digital Learning in Delhi [18-19 October 2005], the participants sat bemused as Dr. Sugata Mitra of NIIT gave a very engaging account of his ‘Hole in the Wall’ project. Dr. Mitra explained how Delhi slum children with no education and no knowledge of English quickly picked up different computer functions, when given unsupervised access to a computer and the internet through a kiosk.

This project in ‘minimally invasive education’ was later extended to rural India, prompting a rather disbelieving audience to ask how the Hole in the Wall computers could function in remote and rural India, with erratic electricity supply, negligible telecom penetration and next to no maintenance.

Dr. Mitra gamely reeled off a catalogue of solar-powered UPS, self-rebooting, maintenance-free PCs, VSATs and other marvels of digital technology that could presumably keep computers running forever in the boondocks, but it sounded more like a Heath Robinson whimsy than a recipe for ICT in education.

Not surprisingly, the recommendations that emerged from the discussions emphasized “the need to think of ICT in education beyond computer aided learning and incorporate other technologies like community radio and other media. These mediums would not only be cost effective but also have a greater outreach potential.” [Digital Learning, Vol 1 Issue1, Nov-Dec 2005]

Classrooms and radio have always gone together, and radio has been used to teach everything from mathematics in Thailand (Galda, 1984) to civics education in Botswana (Byram, Kaute & Matenge, 1980). The first School Broadcast project in India was commissioned as early as 1937. Over the years, various educational radio projects have been carried out in the country, with mixed results.

Educational programmes on AIR
All the Primary channels of All India Radio (AIR) broadcast educational programmes on a regular basis on fixed time slots. AIR’s educational programmes are aimed at students as well as teachers of primary, middle, secondary and senior secondary schools, and are generally produced in collaboration with national educational agencies like NCERT (National Council for Educational Research & Training) and CIET (Central Institute of Educational Technology).

The Language Learning programme, popularly known as the ‘Radio Pilot project’, was started in 1979-80 jointly by AIR and the Department of Education (Rajasthan). Its aim was to teach Hindi to school children as their first language in 500 primary schools of Jaipur and Ajmer districts, on an experimental basis. The broadcasts were found to be useful in improving the children’s vocabulary, and a similar project was initiated in the Hoshangabad district of Madhya Pradesh.

Apart from AIR’s in-house educational programmes, the Indira Gandhi Open University (IGNOU) also broadcasts its educational programmes from AIR studios.

IGNOU-AIR Interactive Radio Counseling (IRC) was launched in May 1998 for students of Open / Conventional Universities. AIR Bhopal and IGNOU ran this as an experimental programme for a year, to provide academic counseling in various subjects and to instantly respond to students’ queries; but with its success, it was extended to other AIR stations. Presently, Interactive Radio Counseling is being provided every Sunday for one hour from 186 radio stations of All India Radio.

Gyan Vani

IGNOU’s own Gyan-Vani (Educational FM radio channel) was launched was in November 2001 to extend mass media support for education, suited to local needs. Gyan Vani channels are operating at present in 17 cities, and are scheduled to expand to a total of 40 cities by 2007. Gyan Vani stations operate as media cooperatives, with programmes contributed by different educational institutions, NGOs and institutions like IGNOU, NCERT, UGC, IIT, etc.

Each Gyan Vani station has a range of about 60 KM radius, covering an entire city or town and its surrounding area. Gyan Vani is meant for both conventional and non-conventional education, addressing local educational, developmental and socio-cultural needs. The stations broadcast in English, Hindi and the language or dialect of the region, for 4 to 12 hours daily.

During the current phase of private FM expansion in India, which is expected to cover 91 cities, it is reported that the government plans to offer 87 FM channels to be used exclusively for education. Of these, 36 would be used by IGNOU, while the other channels would be open to private players.

Community radio initiatives in India
In the absence of true community radio in India, a number of NGOs are using innovative methods for non-formal education through audio. School Audio through cable has been in operation in Budhikote village, Karnataka, since January 2002. The School Audio project is a spin-off of the ‘Namma Dhwani’ cable audio service being run in Budhikote by VOICES, a development communication NGO. Twice a week, educational programmes are ‘cable-cast’ to the local government school.

In the Kutch region of Gujarat, the Kutch Mahila Vikas Sangathan (KMVS), an independent organization of rural women, focuses on adolescent girls’ education, basic functional literacy within sangathan members and development of context specific educational curricula on different issues for literates and neo-literates.

In 1999, KMVS launched a weekly radio programme ‘Kunjal Panchchi KutchJi’ for expansion of literacy as well as to build an information network. The 30-minute serial is broadcast in the local Kutchi dialect, over All India Radio’s local stations in this region of vast distances and poor communications. constantly hampered by the lack of radio sets in classrooms, the difficulty of coordinating school broadcasts with class-room timings and more significantly, by the lack of good broadcasters who have a passion for education and conversely, of teachers who are also good broadcasters. Using car hire Fort Lauderdale Airport gives perfect service after the visit from India.