Saturday, March 22, 2008

Sirius to Launch New NGSO Satellite

Sirius recently filed an application for authority to launch and operate a new non-geostationary orbit satellite (NGSO, FM-6). The satellite will replace TWO existing NGSO satellites (FM-1 and FM-2) that are currently in operation. FM-6 would be placed half way between the where FM-1 and FM-2 operate today. The launch is expected to take place in 2010. Sirius has already been granted authority to launch a geostationary satellite (FM-5). This will significantly alter its existing satellite constellation. It will eventually operate with two non geostationary satellites (FM-3, FM-6) and one geostationary satellite (FM-5). Sirius explains it as follows:

The enhanced geographic coverage anticipated from the successful launch of FM-5, coupled with satellite technology advancements included on FM-5 and FM-6, will allow Sirius to reduce its GSO constellation from three to two satellites.

FM-6 will have twice the transmit power of FM-1 and FM-2.

In the appplication, there is this little nugget of information concerning its overlay modulation currently used for backseat video:

The digital stream throughput is 1.35 Mb/s. The additional transmission capacity will be used for providing subscribers with more audio channel programming and data and is currently providing three compressed video channels primarily for vehicle back seat viewing. Each video is compressed to approximately 255kb/s.

This gives us some ideas on what we might see for the number of audio channels. Presently, music is compressed to 44 kbps; voice, 20 kbps; and 16 kbps for low quality audio such as traffic and weather. The above implies spare capacity of 585 kbps, enough for 13 more music channels.


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2 comments:

DogstarRadio said...

Am I the only one who has a hard time understanding why Sirius is giving up most of its bandwidth for three video channels which could be used for 200 audio channels (or better quality on existing audio channels along with plenty of room for more new audio).

Kids are happy with DVDs they don't need the real-time live video that backseat video can provide. Why dedicate so much bandwidth to something that other, much cheaper, media can handle better?

Anonymous said...

Sirius Is backed by extremely deep pocketed investors who are somewhat Camera shy. So this alocation is a lure for a potential buy out of Sirius radio the stock has plumeted and sirius is crying poverty - Watch Sirius and how this company is growing and wil continue to grow and by the way BUY SOME STOCK IN IT KNOW!!!