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[ale] Wandering OT: Re: Car PC's and internet radio?



On Apr 17, 2007, at 11:09 PM, Jeff Hubbs wrote:

> Dale Heatherington wrote:
>> Relax.
>> Satellite radio is like AM or FM or TV broadcasting - IT'S ONE->
>> WAY.
> Do you know this as fact, or are you presuming it?  Can you point  
> me to
> a specification or, better yet, otherwise demonstrate that it's
> downlink-only?

I've been messing with radio for at least 45 years.  I have an  
amateur radio license.  I've designed and built many receivers and  
transmitters.  I've designed and built RF modems .  http:// 
www.wa4dsy.net/  I do know something about the subject.

But more to the point, I have taken apart an XM radio for  
"research".  I have looked at data sheets of the chips used in said  
radio.  There is no transmitter.  I've read information about the XM  
system.  I've seen nothing to suggest there is an uplink of any kind.

Do a google search on STA450A
also STA400A

Those are XM channel decoder chips.
Unfortunately  I can't prove that XM transmitter chips do not exist.  
Negatives tend to be hard to prove :)

Here's some info about how XM works.
http://illumin.usc.edu/article.php?articleID=32&page=1




>

--
Dale Heatherington
Windows free since '93
http://www.wa4dsy.net



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