Satellite radio systems are actually part of a larger group of broadcasting mediums, which specialists refer to as Digital Multimedia Broadcasting or DMB. This digital transmission system is used in order to send data to different receivers such as radios, television sets or mobile phones and PDAs. There are two different ways of using digital multimedia broadcasting - S-DMB which is broadcasting via a satellite or T-DMB which uses terrestrial emitters. The complexity of the entire digital multimedia broadcasting field is huge. Out of all the features and characteristics digital broadcasting offers, satellite radio is probably the most spectacular as it generated immense interest and triggered an intense competition between the two main satellite radio broadcasters, Sirius and XM Radio. The development of satellite radio and other forms of digital broadcasting is spectacular because it offers two main qualities that terrestrial emitters are deficient in: quality and coverage. In the case of satellite radio, for example, the sound quality from a satellite broadcast is much higher than AM or FM broadcasts, as the hissing noises and transmission disturbances are eliminated.

Technical features of digital multimedia broadcasting - overview

Whether it refers to television, satellite radio or cell phone transmissions, digital multimedia broadcasting is based on the Eureka 147 DAB standard. Digital television uses the T-DMB which is made for transmissions on frequency bands III (VHF) and L (SHF). T-DMB is an ETSI standard (TS 102 427 and TS 102 428).
T-DMB uses MPEG-4 Part 10 (H264) for the video and MPEG-4 Part 3 BSAC or HE-AAC V2 for the audio. When it comes to satellite radio, there were a few issues to be resolved by the main satellite radio broadcasters. The satellite radio receiver needs to be in the line of sight of the satellite to receive the transmission - and there is the problem of having different landscaping objects block the direct transmission. Land based devices were installed in order to eliminate the lack of direct satellite transmission. Since the wider spectrum of broadcasts has to be covered, digital multimedia broadcasting uses OFDM-4DPSK modulation and a chip of T-DMB receiver is also provided by MPEG-2 Transport Stream De-multiplexer. This helps reduce the negative effects of shadowing and fading, present in many digital transmissions.

The future of digital multimedia broadcasting

The transfer from the analog world to the digital one is obvious in all fields of work. Since digital multimedia broadcasting is developing so quickly, there is a silent battle going on between the new age digital technology and the classic analog one. OF course, many compare the transition from the analog to the completely digital era with the way audio cassettes were replaced by CDs and later on even DVDs. However, the development of digital multimedia broadcasting is slower since it happens on so many levels at the same time. Digital television is taking us into new spaces that are basically hybrids of the features of regular TV and characteristics of the Internet. Satellite radio is also taking huge leaps forward, with more and more programs having satellite radio exclusivity. There are even discussion of moving events like the MLB exclusively on satellite radio, which would provide one of the first deadly strikes against terrestrial radio broadcasting. Digital data transmission is fast and accurate, and so far reality proves that the satellites used in order to facilitate broadcasting and reliable. Most digital multimedia broadcasting companies that own satellites also have backup ones ready to go in orbit and replace a defective one. Some other benefits of digital multimedia broadcasting recommend it as a next step in the development of broadcasting. From the consumer’s point of view, the quality and interactivity options of digital TV or satellite radio broadcasts are important features. Although most digital multimedia broadcasting channels and technologies are still complex and sometimes expensive, the evolution of digital broadcasting seems to be here to stay.

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Broadcasting digital radio via satellite is not something new and concepts of doings this have been with us for a few years. From the early days of satellite radio, companies like Dish Network have offered digital audio channels as part of their programs. The breakthrough in popularity of satellite radio, however, happened just recently, when the technology became more permissive. Satellite radio was very rare on moving locations, such as boats or cars, mostly because there was the need for some expensive equipment - a tracking dish. This was a strong deterrent which kept satellite radio quite unknown by the general public. Today, however, one can receive digital audio satellite broadcasts by using a small, GPS-like antenna. This greatly increased the feasibility of the satellite radio systems and more and more vehicle owners began considering satellite radios as a good source of music and news.

The birth of satellite radio in the United States

When the U.S. Federal Communications Commission (FCC) allocated a spectrum in the “S” band (2.3 GHz) for the broadcasting of digital radio services in 1992 no one thought the amplitude that the system would take in the future. From the initial Digital Audio Radio Service (DARS) things progressed until two companies were given licenses to broadcast digital radio in 1997. These two were American Mobile Radio (today known as XM Satellite Radio) and CD Radio (presently called Sirius Satellite Radio). The fact that satellite radio is nationwide makes it a very attractive media channel, both for commercial and non-profit organizations. The two companies that initiated the development of satellite radio saw the huge potential it had, since it wasn’t confined by the limitations of other terrestrial broadcasters.

Benefits of using satellite radio

Here are some of the most noteworthy benefits of having a satellite radio system:

* No more geographical limitations - since the radio program is broadcast through a satellite you don’t have to switch radio stations every time you leave a certain coverage area.
* The digital quality of the satellite radio has some amazing benefits on its own. There are no noise disturbances that were traditional to FM and AM broadcasts. The transmission is crystal clear and satellite radio receives some valuable points when broadcasting quality is concerned.
* Analog radio stations simply cannot broadcast the full range of sounds available through digital satellite radio.
* Both XM Radio and Sirius Radio can be picked up on all the US territory and they are also available in some parts of Canada and Mexico.

Satellite radio technology

Each of the major satellite radio services uses its own equipment to broadcast the signal to their clients. The competition is tight and customers have to “pick sides” in order to benefit from satellite radio broadcasting. You have to choose your preferred company and purchase adequate receivers for that particular company. Both XM Radio and Sirius Radio provide their clients with different ways of receiving their services. The field where most competition takes place is in the negotiation with the major automobile manufacturers. Both XM Radio and Sirius Radio have deals with the auto industry giants in order to offer their services and equipment as optional on the car models they produce. Other partnerships were created with audio equipment manufacturers, who now offer satellite radio transceivers and matching headsets. The most recent shock in the satellite radio universe was caused by the production of portable MP3 player-like satellite radio receivers.

The future development of satellite radio

One of the main problems of satellite radio was addressed by the main satellite radio broadcasters. Since you need to be in the line of sight of the satellite to receive the transmission, different problems appeared with mobile satellite radio receivers, especially when different landscaping objects blocked the direct transmission. To solve this, land based devices were installed in order to eliminate the lack of direct satellite transmission. Another interesting aspect related to satellite radios is that they approached their service offers from a different perspective than traditional radio broadcasters. Instead of airing commercials they charge a subscription fee. For many people, this is actually the best alternative, since they get an almost 100% content broadcast (whether it’s music or talk shows) without the 10-12 minutes per hour of annoying commercials. In most cases, the monthly subscription for satellite radio is of around $12.

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The satellite radio world is divided among the two major broadcasters, XM Radio and Sirius. Since they work on different frequencies and need specific equipment to broadcast, Sirius and XM Radio have divided the market into two groups. While some are fans of the Sirius channels others prefer XM Radio, and the debate regarding which of the two is the best could go on forever. Some however are subscribers to both services, since they love some of the Sirius programs but also enjoy XM Radio broadcasting. For them and for more people interested in satellite radio, there are some potential good news. Interoperable satellite radios are one of the things most of the major players in the satellite radio industry are talking about. What are they? Basically they are receivers that can work both with Sirius and XM Radio and everything is enclosed in a single unit.

Interoperable Technologies - when Sirius and XM work together

Interoperable Technologies is the name of a joint effort funded by both Sirius and XM Radio, with the declared purpose of bringing dual-subscription satellite radios to the general market. Founded in 2003, Interoperable Technologies has started developing the dual-mode satellite radios ever since and progress is being made with each passing month. Interoperable Technologies gets help from consultants from both XM and Sirius and their 2005 success of developing a singe unit that can receive both transmissions was a notable one. Today, Interoperable Technologies ha a deadline of bringing the developed receiver unit to the market. The monthly subscription price is estimated to be around $26 - for which you get over 300 channels from the combined broadcasting list of the two satellite radio operators.

What the people say

The news of the interoperable satellite radio development has triggered interesting responses among XM and Sirius satellite radio subscribers. Here are some of the things people left on forums and discussion boards regarding this development:

“$26/month? A hell of a lot cheaper than cable TV.” Says one of the forum posters. He is right, but, of course, many will question the need to pay $26 for over 300 radio channels out of which 80% will probably never get listened to.
“Oh man! As a dual subscriber, this would be SO cool to have. Where do I sign up?” - on the other hand, of course, there are those people that don’t mind spending a little extra when they can get so much more.
“Cool idea if it ever comes to pass. Even though I only subscribe to Sirius, I would consider buying this with an eye on the future…” - for people such as this forum poster, the interoperable satellite radio system is the natural evolutionary step forward, so it is definitely worth looking into.
Implications of the interoperable satellite radio system
As you can see from the response of the potential customers, the interoperable satellite radio system is an interesting development. While Sirius and XM are lucky enough to be the only major players in this field, for now, it seems they are also ready to work together in order to consolidate their future. Of course, offering twice the programs on a single unit is a major step forward, and from the early stages it seems that the target audience is ready to receive the single receiver unit with applause. On the other hand, is this an initial enthusiastic response or is it genuine interest? Won’t 300+ channels become too much and won’t people start to feel like they are paying for something they are rarely using? There will also be some interesting things to follow as far as exclusivity rights go, because each of the two broadcasters have their own original approaches to common things. Another interesting aspect to follow will be how the sales for individual Sirius and XM units will go after the dual receiver hits the market. For many, the combined efforts of Sirius and XM tend to look like a first step towards a large scale joint venture that will lead to an absolute monopoly of the satellite radio market.

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Any song you hear on satellite radio stars as a recording in a specific format on different recording mediums. IN most cases, the recording quality has to be maintained fairly high, usually around 384kb/s, while also being reasonably small enough to be transported on CDs and DVDs. The music tracks used in satellite radio are cataloged using a similar system to the MP3 cataloging criteria, the ID3 tags. The choice for the music tracks that will be played is made by each channel individually. The DJ selecting the tracks usually chooses about 20-30 minutes worth of music. The DJ has to listen to the tracks to make sure they are in proper condition and then simply lets the computer decode the original file. The same thing is repeated once the initial 20-30 minutes are exhausted and the music playing cycle repeats itself.

Sound encoding in satellite radio

Encoding is one of the key elements of digital radio. Each channel is handled by a different encoder. The encoder basically takes the analog file and turns it into a digital one. The digitalization process is made in real time and the music files are transformed into 1’s and 0’s. This process is carried out by powerful computers that analyze sound waves and frequency and break them into binary code. The encoding process is carried out at 128kb/s, 44.1Kh which is actually CD quality. After the song is encoded, it is transmitted to a multiplexer where other channels are also present - the multiplexer basically takes all the channels of the satellite radio provider and combines them into a single broadcast transmission. The data is then sent to a satellite modem device which modulates the data and sends it to the broadcaster’s satellites, using unique transmission frequencies.
What happens above the Earth
Here is where the satellites are located. They receive the transmission and transmit it to the receivers we have in our homes and cars. The satellites are located at 23,000 miles above us - both Sirius and XM Radio use satellites located at this distance from the Earth. The satellites are located in geo-sync, which means that hey orbit above the location they are designated to service at all times. When the satellite receives the transmission encoded at 128kb/s, 44.1 khz it rebroadcasts it to the geographical area it covers. Both Sirius and XM Radio use satellites that cover certain areas of the United states - mostly the East and West coasts. For example, one of XM Radio’s satellites covers the western part of USA, probably an area located roughly from Seattle to San Diego on the West and Minneapolis to Houston on the east. The increased sound quality is possible because the broadcasted data (music tracks, news, sports transmission) don’t get sliced up too many times in the decoding process.

The antenna

The antenna connected to your satellite radio receiver picks up the transmission on L-Band. The recent technological advances have allowed digital radio broadcasters to create receivers small enough to fit mobile locations. In the early days of satellite radio, a large parabolic dish would have to be mounted on the car in order to receive signal. Also, before the more compact receivers were created, the early satellite radio receivers needed electronic movements that directed the dish towards the satellite line of sight. Modern flat panel receivers have eliminated all the problems of their predecessors and can be fitted almost anywhere without taking up too much space.
The receiver and the output
The receiver is the device that decodes the data, basically doing the exact opposite of what the encoding process was like. After receiving the signal from the antenna it amplifies it and converts it to usable sound. The car or home audio system is then able to play the selected satellite radio channel. The rest of the process is exactly like analog broadcasts would work, with an amplifier and speakers outputting the sound.

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XM Radio provides over 150 programs that include music, sports and entertainment, traffic and weather channels.

The music area has the largest number of channels. Here are 68 music channels that you can enjoy and where you can listen to your favorite music whether is from the 60s, the 90s or it’s the new released music. There are music-by-the-decade channels that include the 40s, 50s, 60s, 70s, 80s and 90s songs which are mostly pop/rock outlets, the Top 20 channel, Love Songs, Movie Soundtracks, Show Tunes, MTV, VH1, and a Global hits channel. For those you prefer new music there is the Unsigned channel and the XMU channel. The last one can be compared to a college station. If you are a jazz fan, XM offers you live music from the Blue Note club and the B.B. King Club in New York City.

There are entertainment shows on XM radio hosted by Tom Perry, Snoop Dog or Quincy Jones. Comedy shows may be found on the High Voltage channel where shock jocks Opie and Anthony do their job now uncensored. In totally, XM has three comedy channels including a family comedy channel. Beside these, there are more radio channels like Playboy Radio and Public Radio hosted by Bob Edwards which includes a line of NPR shows that you can enjoy whenever you like.

If you are a sports fanatic you can choose from a good variety of channel dedicated to sports that are provided by XM radio. This includes college football and basketball, NASCAR and Major League Baseball. You can easily listen to the Bowl Championship Series to find out which team is going to the next level, the NCAA Division I football champion.

With a subscription from XM, you will have 38 channels of sports, news and talk channels. For example, ABC News & Talk, BBC World Service, CNBC, Court TV, C-Span, CNN, CNN Headline News, Discovery Channel, E Entertainment, two ESPN channels, Fox News, NASCAR Racing are a few talk station to which you can listen. Local weather and traffic channels are provided too and in totally, they are 22 channels.

Sound clearance depends on the subscription you have. If you have satellite radio from XM, the sound has more quality than the one from Sirius, but still you can’t say that is the same as a CD. You can say that the sound is somewhere between the sound of a CD and AM radio. Hopefully, in the years that will come, the sound quality will improve.

As this technology appeared so did a new line of hardware that can match people’s desires.
And XM has new things to offer like the Delphi XM MyFi which is a small receiver, actually the smallest in the world that can include up to five yours of XM content to which you can listen anywhere you like. Another is the Delphi SkyFi2 which has a TiVo-like 30-Minute Replay feature so, you can rewind, push the pause button or just play it forward to hear music, news or anything else you stored on the it. This equipments are also produced by Sony, Alpine, Pioneer and of course others.

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