Re: Digital TV quality
- From: JosephKK <joseph2k@xxxxxxxxxx>
- Date: Sun, 08 Jan 2006 21:52:06 GMT
Ken Taylor wrote:
> "Joel Kolstad" <JKolstad71HatesSpam@xxxxxxxxx> wrote in message
> news:11pu6nk3tennm4e@xxxxxxxxxxxxxxxxxxxxx
>> "Rich Grise" <richgrise@xxxxxxxxxxx> wrote in message
>> news:pan.2005.12.13.02.51.38.403182@xxxxxxxxxxxxxx
>> > On Sat, 10 Dec 2005 09:21:02 -0700, Luhan wrote:
>>
>> > The customers would still need a dish, unless your satellite had 100
>> > acres of solar panels or a nuclar plant to put out the gigawatts that
>> > it would take for your customers to pick up your programs with a
>> > dipole.
> :-)
>>
>> The satellite radio guys manage to make do with a low gain patch antenna
> for
>> the receivers. Granted, it does tend to need to be outside or at least
> next
>> to a window, and their total bandwidth wouldn't accomodate more than a
>> couple of TV channels, and they're supposedly the most powerful
>> satellites every put into orbit (XM's is 3kW transmitted -- see
>> http://www.spaceref.com/news/viewpr.html?pid=3480), but still -- it'd be
>> a start!
>>
>>
> Cough, splutter! That information is almost 5 years old, so "most powerful
> ever" is a little outdated now, if it was even accurate then. They
> concentrate their power into relatively small data streams over
> continental US (and Hawaii and Alaska? Not sure off-hand), so it's not 1/3
> of the Earth. You just can't get enough energy per bit over a hemisphere
> if you want to stack lots of bits into the signal. Not with anything we're
> able to put up today, anyway. You could put up several satellites and use
> spot-cells or beams, but even then....
>
> Ken
>
>
I suspect that claim is deluded also. The tiny dishes that satTV providers
use are only about 20 dBi and patch antennas are about 6 dBi. The total
bandwidth for 500 channels of video is much greater than xm's 100 channels
of audio. And these satellites predate xm's.
--
JosephKK
.
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