Satellite Radio---XM,SIRIUS & WorldSpace

I was introduced to the satellite radio few months back when I had chance to drive Ford Edge with the built-in Sirius.And in a matter of days ,the depth and breath of it programming and the superb static -free digital sound quality hooked me up .

Satellite radio started with entry of XM in 2001 and they have target themselves specifically to the soft automobile market.Out of the three operators, XM and Sirius are beaming to continental America and WorldSpace is available in Asia, Europe and Africa with all of having more then 100 channels.

Now let us look at its working with Sirius as our example.

Sirius radio has three geostationary satellites in a highly inclined,elliptical orbits, with a "look angle"greater than 60 degrees and spends some 16 hours over continental America and two of them are always broadcasting.Besides the this they have about 100 high power terrestrial repeaters in major cities to boost the signal level and transmit power is in the range of 400 to 2000 watts.

The downlink frequency is in the S-band (2320 to 2332.5 MHz) and each satellite spreads its 100 channels across 1000 frequencies within the 4 MHz of spectrum at either end of its allotted band.