[opendtv] Re: Satellite radio
- From: "Bob Miller" <robmxa@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 26 Sep 2007 00:45:20 -0400
And they all are redundant so their data rate is a whopping 4 or 8
Mbps. I get a headache trying to figure it out once again.
Bob Miller
On 9/25/07, John Shutt <shuttj@xxxxxxxxx> wrote:
>
> ----- Original Message -----
> From: "johnwillkie" <johnwillkie@xxxxxxxxxxxxx>
>
> > What this has to do with COFDM is that the modulation scheme employed by
> > XM
> > -- as trumpeted by Bob Miller years ago -- is COFDM.
>
> The Terrestrial Repeaters use COFDM. The Satellites use single carrier
> QPSK.
>
> > I don't know that the XM setup actually uses a single frequency, but I
> > suspect that it does. I don't know that their network in LA uses a SFN,
> > but
> > I suspect that it does.
>
> XM has six frequencies. Four are used for Satellite to receiver, and two
> are used for TR to receiver.
>
> http://www.patentstorm.us/patents/7075946-description.html
>
> John
>
>
>
>
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