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Technology Stocks : Sirius Satellite Radio (SIRI) -- Ignore unavailable to you. Want to Upgrade?

To: Michael Hart who wrote (364)	5/1/2003 5:24:50 PM
From: i-node	Respond to of 8420

Is that your understanding or is there more to it? I think XMSR's are like....... over Alaska .... You didn't ask me but I'll answer you. Check this out... craigbanks.com This wil show you the orbits of all the satellites.

To: Michael Hart who wrote (364)	5/1/2003 6:24:44 PM
From: ALTERN8	Respond to of 8420

Mike, You're partially correct. It's not the quantity of the satellites as only two Sirius satellites are over the continental US at a time. XM uses geostationary satellites not unlike DirecTV. As you know that technology has limitations which are exploited in every cable TV commercial. The angle at which the signal is received is key and obstacles in the way of this angle can cause signal drops. Sirius eliminates this angle problem with their figure 8 eliptical orbit satellites which transmit their signals at a lower angle. This is why XM has had to install ~2000 repeaters in the US and SIRI has installed less than 200. Peace, A8

To: Michael Hart who wrote (364)	5/1/2003 7:44:51 PM
From: ALTERN8	Read Replies (3) \| Respond to of 8420

Mike, Sorry but I didn't answer you correctly enough. Correction and more details: XM employs 2 satellites dubbed "Rock" and "Roll". Rock orbits roughly in line with Atlanta, Roll is due South of Las Vegas. The geostationary orbit allows for cheap, simple repeater stations which receive their incoming signals in exactly the same way as Directv. The downside is that the incoming signals arrive at a pretty shallow angle. In Seattle the signal beam comes in just 35 degrees above the horizon and can therefore be easily blocked by mundane things such as a tall truck in the next lane. Sirius diminishes the low angle problem by placing 3 Sats in a very high elliptical orbit that peaks 29000 miles above central Canada. This orbit means the satellites are always moving relative to the earth but each is in view of the US for 16 hours a day, and two are in view at all times. As a result, the incoming signal always arrives from a higher angle in the sky, making it harder to block - like summer sunshine. Sirius also has SPLEX, from their website: "What is S>PLEX? S>PLEX is an abbreviation of the word “Statistical Multiplexing.” Statistical Multiplexing is a method of dynamically allocating bandwidth on the satellite spectrum to specific channels that need it, when they need it. This means better overall sound quality and superior sound resolution so you hear your music the way it was meant to be heard. " This basically means that Sirius continuously varies the amount of bandwidth used for each stream. In other words, a channel broadcasting a symphony's grand finale is allotted more bits of data to ensure full sound quality, but when the announcer comes on to deconstruct the performance, the data stream shrinks, freeing up bandwidth for another stream. Other info: XM has announced that the power supplies in its satellites seem to be discharging more quickly than anticipated. Only 34 of XM's 69 music channels and two of its 31 talk/variety offerings are commercial free. Neither SDARS company offers Hawaiian music. I hope this information was useful to you. Regards, A8