Introduction to Satellite Digital Audio Radio service(SDARS)

Satellite Digital Audio Radio Service (SDARS):

SDAR is a satellite-based direct-broadcast radio service in which digitally encoded audio entertainment material is broadcast to Earth-based receivers, either directly from an orbiting satellite, or from the satellite to the receiver via a repeater station (This is a special case in which the receiver is in a shielded location). SDARS is a radio communication service through which audio programming is digitally transmitted by one or more space stations directly to fixed, mobile, and/or portable stations, and which may involve complementary repeating terrestrial transmitters, telemetry, tracking and control facilities. Through SDARS compact-disc quality audio is available because of digital transmition is employed.

History of Satellite Radio:

Satellite radio is an idea over a decade long. In 1992, the U.S. Federal Communications Commission (FCC) allocated a spectrum in the "S" band (2.3 GHz) for nationwide broadcasting of satellite-based Digital Audio Radio Service (DARS). Only four companies applied for a license to broadcast over that band. The FCC gave licenses to two of these companies in 1997. CD Radio (now Sirius Satellite Radio) and American Mobile Radio (now XM Satellite Radio) paid more than $80 million each to use space in the S-band for digital satellite transmission. The first satellite based radio launched by XM on Sep 25, 2001, then followed by Sirius on July 1, 2002.

At this time, there are three space-based radio broadcasters:

Sirius Satellite Radio

XM Satellite Radio

WorldSpace Satellite Radio

Importance and significance of Satellite radio:

We all have our favorite radio stations that we preset into our car radios, flipping between them as we drive to and from work, on errands and around town. But when you travel too far away from the source station, the signal breaks up and fades into static. Most radio signals can only travel about 30 or 40 miles from their source. On long trips that find you passing through different cities, you might have to change radio stations every hour or so as the signals fade in and out. Now, imagine a radio station that can broadcast its signal from more than 22,000 miles (35,000 km) away and then come through on your car radio with complete clarity. One could drive nearly hundreds of kilometers without ever having to change the radio station! Not only would you never hear static interfering with your favorite tunes, but also the music would be interrupted by few or no commercials.

Satellite radio companies are comparing the significance of their service to the impact that cable TV had on television 30 years ago. Listeners won't be able to pick up local stations using satellite radio services, but they will have access to hundreds of stations offering a variety of music genres. Each company has a different plan for its broadcasting system, but the systems do share similarities.

XM Satellite Radio, Sirius Satellite Radio and WorldSpace satellite individually provides digital-audio radio services (SDARS), with commercial-free programming, digital-audio quality, and countrywide coverage. Each company offers nearly 100 channels of digital music and talk radio (many of them commercial-free or with a reduced number of commercials) that can be received from coast to coast with no service interruption. Each offering number of music channels, these services clearly provides programming options not available through traditional radio.

One of the main feature of SDARS is SDARS provides almost Commercial free (or Commercials are restricted) programs. And also it provides news, weather forecasts, and sports apart from entertainment-based programs The primary application for this service is constant coast-to-coast coverage of radio for cars. We have all experienced the problem of trying to listen to radio on a long trip. Both AM and FM stations fade in and out as we drive into and out of their coverage area. Portable full satellite radio service available now a days for the car, home stereo and personal radio environments. Car manufacturers have been installing satellite radio receivers in some models for a few years now, and several models of portable satellite radio receivers are available from a variety of electronics companies.

Signal reception is generally poor as well as variable in the cases of AM or FM. With the SDARS systems, radio coverage throughout the 48 continental states is solid and continuous. Unlike for AM and FM channels SDARS signals are available in a unique format

Subscription based radio service:

Because the technology requires access to a commercial satellite for signal propagation; Satellite Radio services are commercial business entities (not private parties), which offer a package of channels as part of their service ?requiring a subscription from end users to access its channels. Satellite Radio Service can be subscribed at a monthly fee of $12.95 U.S. and up which is very much worth full to the service that it gives.

Future of Satellite radio:

SDARS seems to get good market growth because of the following factors. Increasing partnerships of XM and Sirius with Automobile OEM and distribution outlets made the SDARS more popular. Introduction of more convenient hardware smaller and more portable radios for the automobile as well as the home stereo, computer and office and personal environments made possible at the same time.

Home and personal use Industry promotional advertising and awareness campaigns given the SDARS more popular. Sirius and XM now also offer subscribers the option of listening to their programming online. Apart from all of this, price drop of hardware making it more affordable for after market purchase.

Author can be contacted through crsjith@gmail.com for more information about SDARS.

Jith is an Electrical and Electronics Engineer from southern India. Author is an expert in Avionics systems, Automobile systems and have good command over communication protocols.